53515487 sami star functional description

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SAMI STAR Frequency Converters

Functional Description

Code: Revision: Language:

3AFE 53515487 F EN


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Functional Description 3AFE 53515487

Issued by: FIDRI/EIBDate: 1994-01-03File: SFUNCDEC.DOCCreated with: Word for Windows 2.0

Designer 3.1Excel 3.0

Table of Revisions:

Date: Code: Rev.: Remark:

1992-11-04 3AFE 53515487 E New issue, corrections1994-01-03 3AFE 53515487 F

Table of references:

For information on: See:

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3AFE 53515487 Functional Description

CONTENTS Page

1. INTRODUCTION ..............................................................................5

2. FUNDAMENTAL FEATURES...........................................................62.1 PWM techniques .........................................................................62.2 Gate-commutated semiconductor................................................8

2.2.1 Power transistor (GTR = Giant Transistor) ........................ 92.2.2 Gate Turn Off (GTO) thyristor............................................10

2.3 Star modulation ...........................................................................112.4 Additional motor losses ...............................................................132.5 Switching frequency ....................................................................142.6 Full digital control.........................................................................152.7 Serial data communication techniques........................................162.8 Scalar control - vector control......................................................17

2.8.1 Scalar control ....................................................................172.8.2 Vector control ....................................................................23

3. SAMI STAR FREQUENCY CONVERTER........................................263.1 Mechanical design of the Frequency Converter .......................... 26

4. MODULES OF THE SAMI STAR FREQUENCY CONVERTER....... 284.1 Contactor Unit SAFUL .................................................................284.2 Line Converter Unit SAFUC.........................................................30

4.2.1 6-pulse diode rectifier ........................................................304.2.2 12-pulse diode rectifier ......................................................31

4.2.3 24-pulse diode rectifier ......................................................324.3 Line Generating Unit SAFUG ......................................................33

4.3.1 Line Filter Unit SAFUF.......................................................354.4 Thyristor Braking Unit SAFUX .....................................................364.5 Capacitor Bank Unit SAFUB........................................................384.6 Inverter Unit SAFUI .....................................................................40

4.6.1 Optional cards ...................................................................434.6.2 GTR inverter......................................................................444.6.3 GTO inverter......................................................................454.6.4 Parallel-connected inverter units ....................................... 47

4.7 Braking Chopper SAFUK.............................................................49

5. CONTROL PANEL SAFP 11 PAN (Control Panel 1 ^ CP1) ............. 50

6. CONTROL PANEL SAFP 21 PAN (Control Panel ^ CP2) ................536.1 Single-drive control......................................................................546.2 Common DC-bus drive and sectional drive control......................56

7. DRIVE APPLICATIONS....................................................................577.1 Single drive..................................................................................577.2 Common DC-bus drive................................................................58

7.2.1 DC bus ..............................................................................597.3 Sectional drive.............................................................................60

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1. INTRODUCTION

The SAMI STAR frequency converters manufactured by ABB Industry areefficient, economical devices designed for controlling the speed of squirrel-

cage induction motors. The design of SAMI STAR, which is based on the vastexperience ABB Industry has gained with earlier SAMI types, includes thefeatures that have made the earlier SAMI types so popular. In addition, therapid progress in the power semiconductor and microprocessor technologyhas made it possible to develop new features that will further expand theapplication range of the SAMI frequency converters.

The operation of the SAMI STAR frequency converters is based on

- PWM techniques,- gate-commutated semiconductors

o power transistors (GTR),o gate turn-off thyristors (GTO),

- electrolytic capacitors in the capacitor bank unit,- common DC bus (in common DC-bus drives),- full digital control and microprocessor techniques,- serial data communication techniques,- star modulation,- scalar control and, if necessary, vector control,- microprocessor techniques also when implementing the drive applications.

The SAMI STAR application range is very extensive. In addition to the single

drives, SAMI STAR can be used to replace e.g. the DC-motor drives insectional drive applications.

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2. FUNDAMENTAL FEATURES

2.1 PWM techniques

In most cases, frequency converters which include an intermediate DC circuitare used in the speed controlled AC induction motor drives. Figure 2.1 showsthe block diagram of such a frequency converter.

M3~

CONTROL UNIT

MAINS

LINE CONVERTER UNIT

D.C. INTERMEDIATE CIRCUIT

INVERTER UNIT

Figure 2.1. Block diagram of a frequency converter. (EN 5709 7094)

At the input side of the frequency converter there is a line converter unit(rectifier-diode bridge). The pulsating DC voltage from the line converter unit isfiltered on the DC bus through an LC low pass filter. At the output side there isan inverter unit which forms an AC voltage of the desired frequency from theDC voltage. The control unit supervises the operation of the frequencyconverter.

The voltage to be supplied to the cage induction motor must be controlled inan appropriate proportion to the frequency. Frequency converters in which ther.m.s. value of the output voltage is varied by altering the output voltage pulsepattern are called PWM (Pulse Width Modulation) frequency converters.

- In the PWM frequency converters the control rate is high, because thevoltage is adjusted by means of the inverter unit.

- Thanks to the diode bridge, the power taken by the PWM frequencyconverter from the mains is almost entirely active power and thus thepower factor of the frequency converter is approximately 1 in regard to themains.

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In the PWM frequency converters the intermediate circuit voltage is constant.From this DC voltage the inverter unit forms a symmetrical three-phasevoltage of controlled frequency and magnitude. Figure 2.2 shows the outputvoltage of a PWM frequency converter when the pulse number per half cycleis one and three.

Figure 2.2. The output voltage between two phases of a PWM frequencyconverter when the pulse number is one (a) and three (b).

a)

b)

(5709 7108)

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2.2 Gate-commutated semiconductor

Gate-commutated semiconductors are used in the inverter unit of the SAMISTAR frequency converter. There are two types of semiconductors: the powertransistor (GTR) and the gate turn-off thyristor (GTO). Their use in the inverterunit offers the following benefits:

- A simplified inverter construction, as the forced commutated circuits arenot needed and the number of components as well as the size and weightof the inverter are thus reduced.

- The switching frequency of the inverter is 780 Hz. The high switchingfrequency reduces heating of the motor and gives good modulationproperties.

- The frequency converter losses are extremely low, as there are nocommutation losses.

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2.2.1 Power transistor (GTR = Giant Transistor)

The power transistors have earlier been limited to a low voltage range, butcomponents that are also applicable to higher mains voltages are nowavailable.

The transistors used in SAMI STAR are bipolar, triple-diffused Darlingtons.Mechanically, they are insulated modules containing either all powersemiconductors (2 transistors + 2 free-wheeling diodes, figure 2.3) of onephase or, at high currents, the power semiconductors (1 transistor + 1 free-wheeling diode) of one leg.

C1

B1

E

E1/C2 B2

Figure 2.3. Connection of the transistor module

The benefits offered by power transistors compared to those offered by GTOthyristors:

- The rate of rise of the voltage need not be limited while turning off thetransistor, i.e. snubber capacitors are not needed.

- The output terminals of the inverter can be made to withstand short-circuitwithout the need of additional components in the main circuit.

- A GTR is easier to manufacture than a GTO thyristor.

On the other hand, a GTR requires approximately 2 to 3 times more siliconsurface area than a GTO does at the same electrical values. The GTR is thusused at the power ratings of up to 125 kVA, while the GTOs are used forhigher power ratings.

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2.2.2 Gate Turn Off (GTO) thyristor

The difference between a GTO thyristor and a conventional high-speedthyristor is that the GTO thyristor can be turned off by applying a negativecurrent pulse to the gate. The peak value of the required current pulse isapprox. 25 % of the anode current to be turned off and the pulse duration is 10

to 20 µs. The GTO has characteristics of both a thyristor and a powertransistor.

The GTO gives best results when applied in the high-current and high-voltageranges. The GTOs used in SAMI STAR are of the presspack-type (figure 2.4)

Anode

Cathod

Gate

Figure 2.4. A GTO thyristor and its connection.

The rate of rise of the voltage must be limited while turning off the thyristor byconnecting a snubber capacitor across the GTO. Correspondingly, while the

GTO is turned on, the rate of rise of the current must be limited by means of adi/dt choke.

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2.3 Star modulation

The modulator is a program segment which controls the powersemiconductors so that AC power of the desired frequency, phase and voltageis generated. The modulator of SAMI STAR is optimized to minimize distortionin accordance with the star modulation theory.

The star modulation method was developed for full digital control. It wasdeveloped considering the special requirements set for the modulator byvector control. The special requirements are:

- zero frequency,- zero voltage,- reversing at zero frequency,- voltage controllable regardless of frequency,

- voltage controllable over the entire frequency range.

The modulator uses two modulation methods:- asynchronous: the number of times the switch is turned in a given time

unit remains constant. This makes zero frequency and smooth reversingpossible. In addition, the distortion of current remains small.

- synchronous: the number of the mains voltage pulses per half cycleremains constant. This makes smooth running at high frequenciespossible. The pulse numbers are so selected that the distortion of currentremains as small as possible.

∞

Figure 2.5. Switching frequency fk as a function of output frequency f of theinverter unit when the field weakening point is at 50 Hz.

(EN 5709 7116)

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The asynchronous (ASYN) modulation is used in the range 0 to 20 Hz, thesynchronous (SYN) modulation between 20 and 200 Hz. Six different pulsenumbers are used for synchronous modulation:

- 27 20 to 26 Hz- 19 26 to 37 Hz- 11 37 to 65 Hz- 7 65 to 100 Hz- 5 100 to 150 Hz- 3 150 to 200 Hz

In practice, when the field weakening point is at 50 Hz, a transfer is made topulse number 3 at approx. 50 Hz. Pulse numbers 5 and 7 are used if the fieldweakening point is at a frequency above 65 Hz.

When the star modulation is used the switching operations made betweendifferent modulation methods and pulse numbers are smooth.

With respect to the heating of the motor, the star modulation gives, dependingon the frequency, a result which is as good as or better than that given by thesine-triangle comparison at the same switching frequency.

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2.4 Additional motor losses

The frequency converter supply causes additional losses in the cage inductionmotor because the motor currents are not completely sinusoidal but containharmonics. The harmonic content of the current is depicted by the ratio k ofthe fundamental wave and r.m.s. value of the motor current, i.e. thefundamental-wave portion of the motor current, in such a way that the motorloadability at the frequency converter supply is approximately proportional to k.

In figure 2.6 the values of k are compared in certain variable AC-motor drives.The superiority of the new technique in its softness on the motor is apparent,in particular at fractional speeds, which is important for self-ventilated motors.

Figure 2.6. The fundamental-wave portion of the motor current in certain AC-motor frequency converters. (EN 5709 7123)

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2.5 Switching frequency

The switching frequency means the number of times a single switch (GTR,GTO) is turned to and fro in a given time unit. A switching cycle consists ofone turn-on and one turn-off operation.

As the switching frequency increases, the additional motor losses caused bythe distortion of current are halved every time the switching frequency isdoubled. The switching frequency for the SAMI STAR frequency converterseries is 780 Hz.

≈

∆

Figure 2.7. The heating of a squirrel-cage induction motor as a function of

the switching frequency of an inverter (measured on motorHXUR 188 A2, 1.5 kW, 1500 rpm) a) at normal mains supply,b) at frequency converter supply. (5709 7132)

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2.6 Full digital control

The following benefits are achieved by means of full digital control:

- definition of the set points as numerical values,- ideal repeatability of set points and parameters,- high accuracy,- standardized hardware, application-specific software,- reduced number of components and cards, high reliability,- serial data communication and thus reduced need for cabling.

The SAMI STAR control circuits are composed of a protection logic and anINTEL 80186 processor and its peripheral circuits.

A separate protection logic guarantees fast and reliable protection functions.

The processor and its peripheral circuits are used to execute the output-stage-specific programs and to perform the operations required by the programs.The programs are:

- diagnostics,- modulator,- vector/scalar control,- data communications.

The diagnostics programs monitor the condition of semiconductors and current

transducers, detect faults in the tachometer signals and serial datacommunications, and give reports on the operation of the protection logic.

The modulation program controls the switching functions of the inverter.

The vector/scalar control programs perform the motor drive control functions.

The data communication programs transfer data to the external control.

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2.7 Serial data communication techniques

The use of serial data communication means:

- reduced cabling costs,- flexible connection to various data processing equipment,- unlimited number of transferred variables,- improved noise tolerance.

SAMI STAR is connected to external control through a serial data bus.

Connection to the SAMI STAR serial channel can be made through a controlpanel, a terminal, a PC, etc. The channel is implemented by means of a 20mA optocoupled current loop. The baud rate is 4800 or 9600 Bd.

The serial channel is used for all communications between external controland SAMI. The main operations are:

- start/stop,- set-point setting,- reading of actual values,- setting of parameters for the controllers,- transfer of diagnostics messages.

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2.8 Scalar control - vector control

An electric drive is designed to transmit mechanical power to a driven machineto establish a desired operating condition, normally a certain speed or torque.

2.8.1 Scalar control

In scalar control, the speed of the motor is set by adjusting the supplyfrequency. The amount by which the speed remains below the synchronousspeed that corresponds to the supply frequency is dependent on the slip. Theslip settles to a value at which the driven machine will have the power itrequires.

1. AC MOTOR2. INVERTER3. MODULATOR4. UREF CALCULATION5. CALCULATION OF ACTUAL VALUES6. FORMATION OF FREQUENCY REFERENCE7. REFERENCE-VALUE INTEGRATOR8. TORQUE CONTROLLER

9. TORQUE-LIMIT CONTROLLER10. UC-LIMIT CONTROLLER11. CONTROL-MODE SELECTOR12. SPEED CONTROLLER (REQUIRES A TACHOMETER SIGNAL)

Figure 2.8. Block diagram of scalar control. (EN 5709 7639)

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Scalar control includes the following standard functions:

1. Standard program + blocks freely programmable2. IR compensation3. Slip compensation4. S-curve of the reference value integrator5. Trend buffers6. SAFT 154 DAC D/A-converter connection facility

Standard program + blocks

All application functional blocks are available as standard in the scalar controlstandard program.

IR compensation

At the low frequencies (up to 10 Hz) a significant voltage drop is produced bythe stator resistance of the motor. The drop is compensated by boosting theoutput voltage of the frequency converter so that the proper magnetization isalways achieved. This so-called IR compensation is needed e.g. in constant-torque drives that require a high starting torque and in drives that require ahigh release torque.

Slip compensation

Slip compensation is used when constant speed is required irrespective ofchanges occurring in the load torque. The compensation effect can beadjusted in proportion to the slip of the driven motor. The slip compensationdoes not operate at frequencies below 10 Hz.

S curve of the reference value integrator

The operation of the reference value integrator is normally softened at the

bend points by means of a so-called S curve. If the integration time requiredby the drive is short (< 3 s), the softening function begins to increase theintegration times significantly. In that case the S curve can be eliminated.

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Trend buffer

The inverter software contains 8 sampling buffers with 100 samples capacity.The measuring point number can be set to the trend control address which isto be used. A trend triggering occurs every time the inverter detects a fault. Atriggering can also be initiated manually (during operation) or it can be madeto occur when a deviation of two successive samples of a measuring pointmonitored by the first trend buffer is detected.

The shortest sampling interval is 3 ms.

Trends can be examined in analog form by connecting the trend to a printer(printing speed 100 samples/21 s) via the A/D converter of the inverter or byreading trend numeric values on the control panel or via DMS on the screen ofyour PC.

The SAFT 154 DAC D/A converter available as optional extra can beconnected to the inverter control card for a printer or an oscilloscope.

Scalar control also includes the following additional functions:

1. Stall protection2. Running start3. Power loss control4. Torque control5. Speed measurement by means of a tachometer

6. Speed control by means of a tachometer7. DC Braking

An additional function can be selected provided it has been activated in theprogram at the factory.

Stall protection

The stall protection stops the inverter when the motor is in apparent danger ofoverheating. The rotor is either mechanically stalled or the load is otherwise

continuously too high.

Running start

The running start program facilitates starting of the inverter to a running motorwithout braking of the motor first. The inverter searches for a frequency thatcorresponds to the shaft speed of the rotating motor and is synchronized to it. A search can also be made when the shaft rotates in the direction opposite tothe frequency reference.

Large fan drives and centrifuge drives are good examples of suitable runningstart drive applications.

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Power loss control

The power loss control circuit holds the inverter in operating condition duringshort (approx. 0.5 s) power failures. The energy required for operation is thentaken from the kinetic energy available on the drive shaft. If a power failurelasts longer than one second, the main contactor control logic will not be ableto close the contactor any more even if the kinetic energy is sufficient. In thatcase a backed-up auxiliary voltage should be used for the relay block.

Torque control (> 5 Hz)

When torque control is selected for operation, the frequency converter iscontrolled by means of the torque reference. The PI controller tries to keep thedrive torque at the set point by varying the frequency reference.

At frequencies below 5 Hz, torque control is automatically switched tofrequency control.

If torque control is required at frequencies below 5 Hz, the vector controlprogram must be used.

Speed measurement by means of a tachometer

If accurate information about the rotational speed of the motor is required, the

motor can be equipped with a tachometer which is connected to the inverter.The speed is then available as a digital readout on the inverter control panel orit can be obtained as an analog message.

Speed control by means of a tachometer

If the motor is equipped with a tachometer, speed control can be used. Thespeed controller uses a tachometer signal to eliminate the error caused in theshaft speed by the slip of the cage induction motor. The slip is dependent onthe load of the motor. The normal speed control operating range is 5 to 200

Hz. At frequencies below 5 Hz, speed control operates but its controlcharacteristics are slow. The rise time for a step response is 100 ms atfrequencies above 5 Hz.

When more demanding control dynamics are required, vector control must beused.

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DC Braking

DC braking provides a stabile method of braking the motor by injection a DCcurrent into the stator winding of the machine. With DC braking the kineticenergy stored in the rotating masses of the drive is dissipated in the motor.

Application Blocks

The following functions can be implemented by means of the applicationblocks:

1. Process control2. PFC automatic system3. Proportional control

4. Limiting control5. Critical frequency protection6. Flux optimization7. Motor overload supervision

Combinations of the above mentioned functions are possible. The functionscan also be tailored for specific needs by means of the application functionalblocks. A total of approx. 250 functional blocks are available.

Process control

The process control function is used when it is advantageous to have theprocess controller in the frequency converter. Pump and fan drives withpressure, level or flow control are the most common application examples.The process controller is a PI controller.

PFC automatic system

The PFC automatic system (automatic Pump, Fan and Compressor controlsystem) is used e.g. in drives which have several parallel-connected pumps.The speed of one pump is controlled by a frequency converter while the otherpumps are connected direct on line as required. The PFC automatic system

facilitates stepless control of the entire volume to be moved.

A total of 5 pumps at a time can be started.

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Proportional control

The proportional control program is suitable for control applications in whichthe basic drive speed reference is corrected by an additional referencesupplied from another source. An application example is the headbox fanpump control of a paper machine. The proportional effect of the additionalreference on the basic reference is set through a program and is normally afew percent of the basic reference.

Limiting control

The limiting control program is applicable e.g. in a gang mill feeding roll controlor in a pulp mill feeding chain control. The frequency converter is used tocontrol the speed of the feeding motor.

If the main motor (sawing or grinding motor) tends to be overloaded, theprogram automatically reduces the speed reference.

Critical frequency protection

The frequency converter can be programmed so that running at critical speedsis disabled. A total of 5 frequency ranges can be programmed into thememory.

Flux optimization

When the flux optimization is used the motor can be driven with a reduced fluxat frequencies between 10 and 50 Hz, for example. The flux optimizationfunction is designed for pump and fan drives in which the load torqueincreases quadratically in proportion to the speed. The noise level of themotor can be reduced by means of the flux optimization.

Motor overload supervision

The motor overload supervision function includes a simple overload protectionfor the motor in transient overload conditions. The loadability curve of themotor is programmed into the memory (loadability at 0 Hz and at the fieldweakening point). If an overshoot of the curve lasts longer than a presetovershoot time, an overload alarm or tripping occurs.

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2.8.2 Vector control

The torque of an electrical motor is proportional to the current and the flux.We get the fastest torque response from an asynchronous motor if we keepthe flux constant and only vary the current. To keep the flux of anasynchronous motor also during transients constant we must employ a controlscheme called vector control. With vector control the stator current isseperated into two components. One component, called id, is in the directionof the flux vector. The other component, called iq, makes angle of 90 degreeswith the flux vector. By keeping id constant we are able to keep the fluxconstant. We then control the torque by controlling iq.

To be able to seperate the stator current into id and iq, we must know theposition of the flux, which is rotating. In SAMI STAR the position of the flux isfound in the following way. We measure the motor currents and the rotor

speed. These signals are fed to a model of the machine that is stored in thememory of the frequency converter. The SAMI STAR then calculates theposition of the flux. This calculation must be made in real time and wetherefore need a fast microprocessor. Once we know the flux position,

indicated by δ in Figure 2.9, the stator current can be seperated in the flux-oriented components.

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K

n+

u

f s

AM

3

-

act

-

+Machine

Model

Parameter

Identification

+

-

Flux

Control

+

-

Torque

Control

PI

id ref

i

i

i

d act

q ref

q act

ref

+

+

T

nref

ref

1

2

3

4

5

11

10

6

7

8

12

9

1314

n

n

Figure 2.9. Block diagram of vector control. (5709 7141)

1 Rectifier2 DC-Bus3 Inverter4 AC-Machine5 Pulse Generator6 Modulator7 Motor Model8 Coordinate Changer9 Saturation curve10 Torque Control11 Flux Control12 Rotor Time Constant Identification13 Torque reference selector

14 PI-controller (speed)

The parameters for the motor model are determined during commissioning ofthe drive. The parameter identification is automated making thecommissioning easy. Saturation and changes of the rotor temperature arefully taken into account. In fact, the control of SAMI STAR compensates forchanges in the rotor temperature while the drive is operating. This form ofadaptive control is indicated by block 12 in Figure 2.9.

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Vector control can operate in either torque control or speed control mode Thisis indicated by the switch 13 in Figure 2.9. In torque control mode the torquereference is directly applied to the torque controller. In speed control mode anouter speed control loop is activated. The speed of the motor is controlled tothe desired value by means of a speed controller. The speed controller outputfunctions as the torque reference of the torque controller.

The static speed measurement accuracy is 0.01 % of the nominal speed whena tachometer is used giving 1000 pulses per revolution. 10 to 20 ms torquestep responses can be achieved by using the torque controller.

Vector control is suitable for applications demanding good dynamiccharacteristics and/or accurate speed control. The use of vector control givesa squirrel-cage induction motor control characteristics equivalent to those of aDC drive.

Vector control can, for example, be used to prevent flux weakening when theload increases instantaneously and the whole current is needed in the rotor toincrease the torque. In practice, the flux and the torque are controlled byvarying the output voltage and frequency of the frequency converter.

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3. SAMI STAR FREQUENCY CONVERTER

3.1 Mechanical design of the Frequency Converter

When designing the SAMI STAR series of frequency converters, ABB Industryhas utilized the experience gained with the earlier models. One importantdesign objective was the frequency converter's good adaptability to variousdrives and applications. The construction of the SAMI STAR frequencyconverter is based on the advanced module technology. A frequencyconverter application is composed of modules which are assembled andtested as separate units and which are easy to install in a cabinet.

Modules of SAMI STAR are:

- Line Supply Unit SAFUS,- Contactor Unit SAFUL,- Line Rectifier Unit SAFUD,- Line Converter Unit SAFUC,- Line Generating Unit SAFUG, (Not in the scope of module deliveries)- Line Filter Unit SAFUF, (Not in the scope of module deliveries)- Thyristor Braking Unit SAFUX,- Capacitor Bank Unit SAFUB,- Braking Chopper SAFUK,- Inverter Unit SAFUI,

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Figure 3.1. The modules of the SAMI STAR frequency converter in a singledrive. (EN 5709 7159)

The modules are placed in the cabinet one beside the other. The space in thecabinet is efficiently used as the modules are narrow, relatively deep and high.The depth of the modules is, however, so selected that all modules will fit in a600 mm deep cabinet. In single drives, the height of the cabinets is 2200 mm.Modules weighing more than 50 kg are equipped with rollers.

The SAMI STAR modules are designed to be independent of the cabinet

construction as far as possible. The modules are suitable for the ABB MDcabinets, but they can also be installed in cabinets of other manufacturers.

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4. MODULES OF THE SAMI STAR FREQUENCY CONVERTER

The Line Supply Unit SAFUS includes connection devices, a diode bridge, aDC choke and a capacitor bank. In the SAMI STAR frequency converters with

a power rating higher than 200 kVA, the SAFUS is divided into three separateunits:- Contactor Unit SAFUL,- Line Converter Unit SAFUC,- Capacitor Bank Unit SAFUB.

The Line Rectifier Unit SAFUD includes a diode bridge, a DC choke and acapacitor bank at the ratings 250 kVA, 400 kVA/380 V/415 V, 315 kVA/500 V,and 250 kVA/660 V.

4.1 Contactor Unit SAFUL

The frequency converter is connected to the distributing mains via adisconnector and a contactor. The main contactor is used to disconnect thefrequency converter from the mains also in case of a line converter unit failureand in case of an emergency. Possible line converter unit failures are unevenvoltage division in the capacitors of the capacitor bank unit or overtemperaturein the line converter unit.The main fuses of the contactor unit provide short-circuit protection for thefrequency converter.

U > O >

0.5s

220V 24V

SAFT 136 CTSCTU

3 ~

OUT

3 ~

IN

Figure 4.1. Block diagram of Contactor Unit SAFUL. (5709 7621)

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The SAFUB is charged through the charging resistors prior to the closing ofthe main contactor. After termination of the 0.5 s charging period the auxiliarycontactor opens the charging circuit and the main contactor closes. Theoperation is controlled by the Contactor Unit control and supervision card,which also trips the main contactor in certain fault situations. Externalinterlock signals are also directly connected to the control and supervisioncard.

The auxiliary voltage transformer of the SAFUL supplies 220 V to thecontactors of the unit and to the fans of the other modules. In sectional drives,the auxiliary voltage transformer supplies power to all fans of the inverter units.

The SAFUL devices form a separate unit. Power to the contactor unit issupplied either through the bottom of the cabinet or through the top. TheSAFUL is connected to the adjacent line converter unit by means of

connection busbars.

The Terminal Block Card (SAFT 174 TBC) to which the customer signals areconnected is located in the SAFUL unit or in the SAFUS unit at power ratingsless than or equal to 200 kVA. The application-specific devices, such asearth-fault control, overvoltage protection and radio interference protectiondevices, are located in the contactor unit when needed.

The SAFUL contactor units are built for the ratings 250 to 2500 kVA.

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4.2 Line Converter Unit SAFUC

The line converter units used in SAMI STAR are either 6- or 12-pulse diodebridges.

4.2.1 6-pulse diode rectifier

The diode bridge and the electrical mains form the DC source of the frequencyconverter. The DC source is connected to the SAFUB capacitor bank unit ofthe intermediate circuit through a DC choke. The diode bridge is implementedfor different ratings as follows:- diode modules for 40 to 125 kVA ratings,- single-side cooled press-pack diode for 160 to 400 kVA ratings,- double-side cooled press-pack diode for 630 to 2500 kVA ratings.

The RC snubber connected across the diode bridge eliminates short-timeovervoltages.

U1

V1

W1

PE

V51 V52 V53

V54 V55 V56

C51

R51

V57 R52

A C L-

X51S51

X52 F51M51

M

1~N

~

Figure 4.2. Circuit diagram of the 6-pulse line converter unit. (5741 8958)

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The 12-pulse diode rectifier is composed of two 6-pulse bridges with a 30°phase difference at the input generated by means of a transformer.

SAFUL 1.

SAFUL 2.

3

3

3

3

3

+ -

DC - bus

SAFUC 1.

SAFUC 2.

Figure 4.3. The 12-pulse line converter unit in the SAMI STAR frequency

converter. (5779 6529)

Benefits of a 12-pulse line converter unit compared to a 6-pulse line converterunit:

- reduced harmonics, e.g. the fifth and seventh harmonics are not present.- Compared to the 6-pulse bridge, the power output is doubled by using the

same diodes in a 12-pulse connection.

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The 24-pulse diode rectifier is composed of four 6-pulse bridges with a 15°phase difference at the input generated by means of phase shiftingtransformers.

.

3

3

3

3

3

3

3

3

3

DC-BUS

SAFUL 1 SAFUC 1

SAFUC 2

SAFUC 3

SAFUC 4

SAFUL 2

SAFUL 3

SAFUL 4

Figure 4.4. The 24-pulse line converter unit in the SAMI STAR frequencyconverter. (Example of a possible transformer connection)

The benefits of a 24-pulse supply compared with a 12-pulse one consist in afurther reduction of line harmonics. In order to fully benefit from this feature, avery good symmetry of the phase shifting transformers is vital.

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4.3 Line Generating Unit SAFUG

The line generating unit is a normal SAMI STAR inverter unit (SAFUI) whoseterminal block card and control unit program are modified for regenerativebraking operation. This unit is not in the scope of module deliveries.

+

-

CONTROL CIRCUIT

U-SYNC.

IR,IS,IT

LGU

LFU

MAINS

IU

UC

220V

50Hz

UC

M

1~N

~

6

Figure 4.5. Block diagram of the line generating unit. (EN 5709 7175)

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The mains voltage is measured and on the basis of the measured value theline generating unit is then synchronized to the mains.

The line reactor operates as a filtering choke which helps to reduce the linecurrent distortion to a sufficiently low level.

The current transducer provides overload protection for the line generatingunit.

A line filter unit SAFUF, which includes a choke, is always used in connectionwith the line generating unit.

The intermediate circuit voltage (Uc) can be raised above the value which isattainable by means of an ordinary diode bridge. This is done by controllingthe voltage and frequency of the inverter unit. The benefits offered by a line

generating unit compared to an ordinary diode bridge are:

- DC-line reactive power compensation is possible when the Uc voltage is20 % higher than the voltage supplied by an ordinary diode bridge.

- There is no need to overdimension the inverter unit of the frequencyconverter because of the line undervoltage as the Uc voltage isindependent of the line undervoltage.

- Flow of active power in both directions (regenerative braking).- Almost sinusoidal line current.

The line generating units are built for the 160 kVA to 1000 kVA power ratings.

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4.3.1 Line Filter Unit SAFUF

The line filter unit is connected between the line generating unit and the 3-phase mains. The SAFUF is designed to reduce harmonics in the outputcurrent of the line generating unit. The nominal power range of the line filterunit is 160 to 1000 kVA. This unit is not in the scope of module deliveries.

U1

V1

W1

PE

3

4

1

2

13 14

1 2 M

1~N

~

X72S71

F71

X71 1

2

2

4

3

6

1 3 5

L71

1

3

5

2

4

6

U2

V2

W2

F72 M71

1 20~

X72

Figure 4.6. Circuit diagram of the line filter unit. (5742 4796)

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4.4 Thyristor Braking Unit SAFUX

The SAFUX thyristor braking unit includes an antiparallel connected thyristorbridge with its control circuits and a DC choke. The thyristor braking unit isused to implement regenerative braking and it then replaces the line converterunit SAFUC.

The SAFUX is independent in operation. The operation is based onsupervision of the DC voltage and the line current. The power units havepresspack-type thyristors.

SAFUX units are built into three mechanical designs:

1. SAFUX 315 F 500 (250 F 415) and 400 F 6602. SAFUX 500 to 800 F 500 (400 to 630 F 415) and 630 to 1000 F 660

3. SAFUX 1250 to 2000 F 500 (1000 to 1600 F 415) and 1600 to2500 F 660

The control techniques are based on the SAMI BG cards and software:

* Power Supply Card SAMC 11 POW* Thyristor Bridge Control Card SAMC 15 TBC* Interface Card SAMC 19 INF* Interface Card SAFT 181 INF* Motherboard SAFT 182 MOB

* Pulse Amplifier Card SAMT 11* Voltage Measuring Card SAFT 183 VMC

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The voltage-specific matchings are made on the voltage measuring card (Udc)and the pulse amplifier card (mains voltage). The inverter unit STOP signalcan be wired to the SAFUX. The STOP signal prevents unnecessarygenerator mode control operations. In the event of a fault the SAFUX suppliesa potential-free output contact signal.

When the SAFUX thyristor braking unit is used, the following additionalcomponents are required in the contactor unit:

o Synchronizing transformero 48 V DC generating circuits

SAFUX

M

1~

FG

CONTROL

Figure 4.7. Circuit diagram of the thyristor braking unit (5709 9453)

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4.5 Capacitor Bank Unit SAFUB

The capacitor bank unit is needed in the intermediate circuit, because thepower taken from the intermediate DC circuit by the inverter unit (SAFUI) andthe power supplied to the intermediate DC circuit by the diode bridge bothcontain ripple current. The SAFUB is a DC capacitor bank.

3

4

1

2

M

1~N

~

1 20~

PE

R1

R2

L+

L-

X3

X2

X1

X6 X1

X6 X1

2 2

1 1

C1.1 C1.n

C2.1 C2.n

S1X1

X2 M1

A1

Figure 4.8. Circuit diagram of the capacitor bank unit. (5741 5703)

Gate-commutated semiconductors are used in the SAMI STAR inverter unit.Since no commutation circuits are needed, the ripple currents of the DCcapacitor bank are reduced to approximately a third when compared to aninverter unit implemented by means of high-speed thyristors. Thanks to thesmall amount of ripple currents electrolytic capacitors can be used instead ofpaper capacitors. Capacitors are connected in parallel and in series depending

on the power rating and voltage of the capacitor bank.

The compensating resistors distribute voltage evenly among the series-connected capacitors.

A fuse is connected in series with each capacitor in the SAFUBs with powerratings equal to or higher than 400 kVA.

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When a fuse is blown, it disconnects the defective capacitor from the capacitorbank while the rest of the bank continues to operate normally. The capacitorbank unit supervision card gives an alarm of a blown fuse or of uneven voltagedistribution.

When the SAFUB is disconnected from the voltage supply, the capacitors aredischarged each through its own discharge resistor.

The design of the capacitor bank units is such that the units are suitable bothfor single drive and for common DC-bus drive applications.

The nominal power range of the capacitor bank unit is 160 kVA to 630 kVA.

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4.6 Inverter Unit SAFUI

The inverter unit forms a three-phase voltage for the motor from the DCintermediate circuit voltage. The power semiconductors used in the inverterunit are either power transistors (GTR) or GTO thyristors, depending on thepower rating of the unit. There are therefore certain differences in the maincircuits of the unit.

The following standard cards control the inverter unit:

- Power Supply Card,- Pulse Amplifier Card,- Chopper Control Card in the GTO inverter,- Control Card,- Interface Card,

- Terminal Block Card.- Current Measurement Card in the inverter units with In = 1200 A.

The signals are galvanically isolated by means of fibre optic links.See figure 4.9.

M

1~

I/U

I/U

I/U

CP1

I/O

4

V1

µP

V6

U2

V2

W2

V1 V2 V3

V4 V5 V6

1)

M

3~

A HzCP2

Uc

INU

+

-

Figure 4.9. Block diagram of the inverter unit and its peripheral circuits.(5709 5199)

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1 Power Supply Card (SAFT ___ POW). In GTR inverters, the card's poweris supplied direct from the intermediate DC circuit; in GTO inverters, thepower is supplied from the intermediate DC circuit through a powerconnection card SAFT 190 APC. The SAFT 190 APC card is the powerconnection part of the power supply card.

The power supply card supplies stabilized and filtered +14 V, +5 V to thecontrol card of the unit and an AC voltage of 42 V, 80 kHz for the pulseamplifiers. In GTO inverters, the power supply card supplies 42 V AC, 80kHz also to the SAFT 190 APC card, which produces +24 V and +13 Vfrom the 42 V for the interface card SAFT 188 IOC.

In GTR inverters, the SAFT 190 APC function circuits are contained on thepower supply card.

The power supply card is at the main circuit potential. The circuits neededfor Uc measurements (see figure 4.8) are also contained on this card.

2 Pulse Amplifier Card (SAFT ___ PAC, in the inverter units with In = 1200 ASNAT 634 PAC) gives the turn-on and turn-off pulses (GTO) to the powersemiconductors in the order determined by the control card. The GTOinverter units contain one pulse amplifier card per phase. In addition, aseparate pulse amplifier and control card is needed to control the DCchopper.

The pulse amplifiers of the GTR inverter unit are all contained on one card.The pulse amplifier cards include a separate power supply which providesthe supply power for the card from the 42 V, 80 kHz input voltage.

The pulse amplifier cards are at the main circuit potential. All pulseamplifier cards also include logic that monitors the condition of the powersemiconductors and inhibits shoot-through control even if the control cardgave false control signals.

3 Control Card (SAFT 187 CON) is microprocessor controlled and its

operation is fully digital. In addition to monitoring its own operation thecard monitors the operation of the whole frequency converter and givesreport on the following failures:- overcurrent,- overvoltage in the intermediate circuit,- undervoltage in the intermediate circuit,- DC-chopper overvoltage or undervoltage (in GTO inverters only),- short-circuit,- serial data communications fault,- overtemperature in the power unit. After a failure, a report is given on the first six failures.

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The main function of the card is to control the power semiconductors ofthe inverter unit so that correct frequency and voltage is always suppliedto the cage induction motor under various operating conditions.

The control card is programmed either for scalar control, vector control orfor line generating unit control, depending on the application. Variousprocess application programs are also programmed into the control cardmemory.

The control card contains a SAMI-type specific signal matching card (e.g.SAFT 25 F 380).

The control card is at the main circuit potential.

4 Interface Card (SAFT 188 IOC) connects the inverter control unit to thecontrol panel. The connection between the interface card and the controlcard is arranged through fibre optics, which gives an effective galvanicisolation and a signal channel which is insensitive to disturbances comingfrom external sources. The +24 V and +13 V supply voltages for theinterface card come direct from the power supply card.

The interface card is connected with ribbon cable to the SAFT 174 TBCterminal block card which is located in the line supply unit or in thecontactor unit. The customer signals will be wired to the TBC card.

5 Terminal Block Card (SAFT 174 TBC) is used to connect the SAMI cardsSAFT 188 IOC and SAFT 164 AIO to external devices. The connectionbetween the TBC card and the IOC and AIO cards is arranged through 40-and 10-pole ribbon cables.The card includes serial channels for control panel CP2.

All customer signals except the maintenance panel and the associatedserial link are connected direct through the TBC card. The TBC card islocated in the line supply unit or, at power ratings higher than 200 kVA, inthe contactor unit.

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4.6.1 Optional cards

The following optional cards are available for the SAMI STAR frequencyconverter:- Relay Digital Output Card SAFT 175 RDO,- Analog Input/Output Card SAFT 164 AIO,- Analog Input/Output Card SAFT 186 AIO,- Input Card SAFT 162 INP.

The relay digital output card is used when potential-free contact signals areneeded from the digital outputs of the SAMI. The card includes four outputchannels.

The analog input/output card is used in process applications that require agalvanic isolation of input signals, or in which two concurrent analog signals

are needed to control the SAMI. The card includes two galvanically isolatedanalog input channels and two output channels. The card is applicable toinput signals 0...10 V, -10...+10 V, 0...20 mA and 4...20 mA.

Correspondingly, the output signal is a voltage signal 0...10 V, -10...+10 V or acurrent signal 0...20 mA, 4...20 mA.

The Analog Input/Output card SAFT 186 AIO includes only one analog inputchannel, which is not galvanically isolated.

The SAFT 162 INP card is a stripped-down version of the SAFT 164 AIO card.

The INP card includes only one analog input channel.

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4.6.2 GTR inverter

This power-transistor-based SAMI STAR inverter is used at low power ratingsup to 125 kVA.

INTERFACE CARD (I/O)

PULSE AMPLIFIERS

CONTROL

PANEL

POWER

SUPPLY

L1

R1

C1UDCC11 C12 C13

IU

IU

µΡ CONTROL CARD ( )

U V W

n

6

+

-

Figure 4.10. Block diagram of the GTR inverter. (EN 5709 7256)

The power semiconductors of the inverter unit are placed in insulatedmodules, which contain either two transistors and two free-wheeling diodes orone transistor and one free-wheeling diode depending on the power rating.

The power semiconductors do not require du/dt protection. The di/dt protectionis arranged through choke L1. After commutation, the excess energy stored inthe choke and the capacitors C11 to C13 is transferred through snubberdiodes to the clamping capacitor C1 which is discharged to the capacitor bankvia resistor R1.

The control card as well as the power supply and the pulse amplifier card areat the minus potential of the main circuit voltage.

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Optocouplers are used to transmit the control signals of the power transistors.The motor current is measured at two phases by means of Hall-effect currenttransducers.

The self-diagnostics (control card) of the unit checks the condition of powersemiconductors, measuring transducers, pulse amplifiers and control logicafter the switching-on of the supply voltage. If a fault is detected, a fault reportis transmitted to the control panel.

4.6.3 GTO inverter

INTERFACE CARD (I/O)

PULSE AMPLIFIERS

CONTROL

PANEL

POWER

SUPPLY

L1

IU

IU

µΡ CONTROL CARD ( )

U V W

n

6

+

-

IU

C1 C2 C3

UDC

C9CH

Figure 4.11. Block diagram of the GTO inverter. (EN 5709 7264)

In principle, the connection of the GTO inverter is similar to the connection ofthe GTR inverter except that GTO thyristors are used instead of transistors. Inaddition, a DC chopper (CH) is used to feed the energies of the di/dt and du/dtprotection circuits back to the intermediate DC circuit.

The semiconductors of the inverter unit are presspack-type GTO thyristors.Choke L1 is used as a di/dt protection and capacitors C1 to C3 as du/dtprotections for the GTO thyristors.

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The energy stored in the protection circuits is fed to capacitor C9 and fromthere back to the intermediate DC circuit via the DC chopper (CH). This hasresulted in extremely low switching losses. A separate pulse amplifier andcontrol card control the DC chopper.

The motor current is measured at each phase by means of Hall-effectmeasuring transducers.

After switching-on of the power, the self-diagnostics of the unit checks thecondition of each power semiconductor, the current measuring transducers,the DC chopper, the pulse amplifiers, and the control logic. If a fault isdetected, starting is inhibited and a fault signal is transmitted to the controlpanel.

For the unit the worst fault situations are a short-circuit in the output terminals,

an earth fault or a shoot-through in the power unit. In these cases, theprotective measures consist of turning off of the GTO thyristors and stoppingof the frequency converter.

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4.6.4 Parallel-connected inverter units

Control of the parallel-connected inverter units is based on master/slaveprinciple. The operation of the standard control cards which are contained inthe master inverter unit is the same as that of the control cards of smallerfrequency converters. The parallel connection cards collect and process dataon the operation of both frequency converters for the standard control cardsand transmit the control signals of the thyristors to the pulse amplifiers.

The parallel-connected construction is possible only in the following powerratings:

1100 kVA 380/400/415 V 1500 kVA 380 V1400 kVA 500 V 1600 kVA 400 V1800 kVA 660/690 V 1650 kVA 415 V

2000 kVA 500 V

2500 kVA 660/690 V.

M

3~

SAFUL SAFUC SAFUI

(MASTER)

SAFUI

(SLAVE)

SAFUB

f1

f2SAFUB

f1

f2

Figure 4.12. Block diagram of parallel-connected inverter units.

The interface card and the control card are contained in the master unit. Theexternal control connections are the same as those in a standard SAMI. Inaddition, the drive requires the following four parallel connection cards:- SAFT 176 MAC

- SAFT 177 SAC- SAFT 180 PCC- SAFT matching card.

N.B. The balancing choke shown in the figures on this and on the nextpage is available only for the inverter types listed above on theleft side. The inverter types listed above on the right side can onlyfeed a motor with a double stator winding.

The choke is not needed with any parallel-connected inverter if the motor fedby the inverter is equipped with a double stator winding.

47


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U2 V2 W2 U2 V2 W2

W1

V1

U1

SAFT

CON

Communication

interface

SAFT 180 PCC

SAFT 176 MAC

SAFT 1100 F 380

1800 F 660

SAFT 177 SAC

1000 F 660

SAFT 630 F 380

U V W

To motor

W2

V2

U2

+

-

+- - +

Slave Master

DC

busbar

SAFT

IOC

188

187

Figure 4.13. Parallel-connected inverter units.

The drive normally requires an output current unbalance limiting reactor.However, if the motor has two separated identical stator windings with adouble set of connection terminals then the output reactor is not necessary.

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4.7 Braking Chopper SAFUK

In a SAMI STAR with no line generating unit, braking of the motor drive isnormally possible only by utilizing the SAMI and motor losses. The SAMI'soutput frequency is lowered at a rate determined by the decrease of the motorspeed.

The braking power available from SAMI STAR can be increased by means ofa braking chopper.

Uc

BRC BRR

+

V2

V1

RCONTROL LOGIC

&

PULSE AMPLIFIER

Figure 4.14. Block diagram of a braking unit. (EN 5709 7124)

The braking unit is composed of a braking chopper and a separate brakingresistor. The braking chopper (SAFUK) is a separate unit which is directlyconnected to the intermediate DC circuit of the frequency converter. When theintermediate circuit voltage increases above the allowed limit during braking,the braking chopper begins to operate and feeds the power supplied to theintermediate circuit from the motor to the braking resistor R (SAFUR). Thechopper control logic controls the power fed to the braking resistor byadjusting the conducting times of the GTO thyristor V1. The free-wheeling

diode V2 protects the GTO thyristor against peak overvoltages in turn-offconditions.

Braking choppers are built for 63 kVA to 250 kVA power ratings.

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5. CONTROL PANEL SAFP 11 PAN (Control Panel 1 ^ CP1)

The control panel CP1 is used to control the SAMI STAR frequency converterin single drive applications.

The CP1 is installed in the door of the frequency converter cabinet and itcannot be used for remote control. The panel contains 9 pushbuttons and adigital display. The panel is connected to the terminal block card of theinverter unit through a ribbon cable.

DP

PAR RESET

LOCREM

1

FL01CHOPUNDERVOLT(GTO)FL02CHOPOVERVOLT(GTO)

FL03 AUX.VOLTSFAULTFL04 OVERTEMPERATURE

FL05 OVERCURRENTFL06DC-OVERVOLT

FL07 DC-UNDERVOLT

FL09SEMICON.FAULTU+FL10SEMICON.FAULTU-FL11SEMICON. FAULTV+

FL12SEMICON.FAULTV-FL13SEMICON.FAULTW+FL14SEMICON.FAULTW-FL15OUTPUTFAULT

FL17 COMMUNICATIONFAULT

FL18TACHO LOSSFL19CURRENTMEAS.FAULTFL20MOTOR STALLED

FL21MATCHCARDFAULTFL22MODULATORFAULT

FL25EXTERNALFAULTFL26EXTERNALFAULT

FL28SAMINODEFAULT

SA50NEWEEPROMSA51STOREDTO MEMORY

SA52MEMORYSTORAGEFAILSSA53PARAMETERTOOSMALLSA54PARAMETERTOOLARGESA55 ILLEGALPARAMETER

SA56NO BATTERYBACKUPSA57LOWAC/DC VOLTSA58STARTINHIBIT

SA59 SYSTEMRESETS

0

Figure 5.1. Control panel CP1. (5709 7396)

The panel has the following functions:

- operation commands to the drive (start/stop, frequency reference, etc.),- monitoring the operation (indication of frequency or load),- diagnostics,- drive-specific parameter settings.

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The digital display contained in the panel gives the following failure indications:

- overcurrent,- undervoltage,- overvoltage,- overtemperature,- semiconductor fault,- processor fault,- line supply unit fault (digital input),- external interlock (digital input).

The control panel can be used to set parameters, e.g. the following:

- integration time for the frequency reference,- minimum and maximum frequency,

- torque limit,- field-weakening point,- starting torque maximizing,- crawl speed.

CTU LCU

CBU

CP1

M

3~

INU

3~

AC IN

Figure 5.2. Control panel CP1 in a single drive.(5709 7418)

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DP

PAR RESET

LOCREM

1

FL01CH OPUNDERVOLT(GTO)FL02CHOPOVERVOLT(GTO)

FL03AUX.VOLTSFAULTFL04 OVERTEMPERATUREFL05OVERCURRENTFL06 DC-OVERVOLT

FL07DC -UNDERVOLTFL09SEMICON.FAULTU+FL10SEMICON.FAULTU-

FL11SEMICON.FAULTV+

FL12SEMICON.FAULTV-FL13SEMICON.FAULTW+FL14SEMICON.FAULTW-

FL15OUTPUTFAULTFL17COMMUNI CATIONFAULTFL18TACHOLOSSFL19CURRENTMEAS.FAULTFL20MOTORSTALLED

FL21MATCHCARDFAULTFL22 MODULATORFAULTFL25EXTERNALFAULTFL26EXTERNALFAULT

FL28SAMINODEFAULT

SA50NEWEEPROMSA51STOREDTO MEMORY

SA52MEMORYSTORAGEFAILS

SA53PARAMETERTOOSMALLSA54PARAMETERTOOLARGESA55ILLEGALPARAMETER

SA56NOBATTERYBACKUPSA57LOWAC/DCVOLTSA58STARTINHIBIT

SA59 SYSTEMRESETS

0

1

3

4 6

5 7

8 10

9

2

Figure 5.3. Operations on the control panel CP1.(5709 7396)

1. Six-digit display2. Display selection: frequency reference, actual value of frequency or

current.Selection of parameter value.

3. Starting the inverter4. Stopping the inverter5. Frequency reference increases, the parameter number or value increases6. Frequency reference decreases, the parameter number or value

decreases7. Selection of parameter number

8. Selection of local or remote control9. Fault reset or storing of parameter value10. Programmable key (reversing)

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6. CONTROL PANEL SAFP 21 PAN (Control Panel ^ CP2)

The SAMI STAR control panel SAFP 21 PAN (figure 6.1) is designed forcontrolling ABB Industry AC and DC drives. The panel contains 12

pushbuttons, a 16-character alphanumeric fluorescence display and amicroprocessor-controlled control unit.

The control panel enclosure is made of plastic and aluminium and itsenclosure class is IP55. The control panel can be installed in the door of an AC or DC drive cabinet, in the control room desk or as a separate unit it caneven be placed close to the driven machine.

F0

START

STOP

+

-

F1

F2

F3

PAR

CTRL

RESET

+125.6 +125.5 38.5

Figure 6.1. Control panel CP2. (5709 7442)

The control panel has the following functions:

- operation commands to the motor driveo start/stopo frequency settingo direction of rotation

- indications of the operating conditions of the motor driveo ready to start

o currento frequencyo process value

- fault indications from the SAMI's diagnosticso overcurrento semiconductor faulto tachometer fault, etc.

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- indication of the test-point valueso flux angleo intermediate circuit voltage, etc.

- setting of process reference in single driveso level controlo speed controlo limit control, etc.

- setting of parameterso tachometer matchingo frequency limitso control gains, etc.

6.1 Single-drive control

The control panel can be used as an independent unit to control a separateSAMI STAR drive. Figure 6.2 shows the block diagram of the control principle.

CTU LCU

CBU

CP2

M

3~

INU

3~

AC IN

Figure 6.2. Block diagram of a single drive. (5709 7451)

If the frequency control alone is sufficient for the application, the basicoperations of the control panel can be used (figure 6.3).

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F0

START

STOP

+

-

F1

F2

F3

PAR

CTRL

RESET

+ 1,7 + 46,22 + 46,22

Figure 6.3. Operations on control panel CP2. (5709 7442)

1. 16-character alphanumeric display, indicating- frequency reference/actual value/motor current- texts: status and fault- parameter number and value

2. Starting of inverter3. Stopping of inverter4. Frequency reference increases, the parameter number or value increases

5. Rapid increase or decrease6. Frequency reference decreases, the parameter number or valuedecreases

7. Programmable key8. Selection of parameter number9. Selection of parameter value10. Fault reset or storing of parameter value

If process control is needed, the control application is constructed by softwiringthe functional blocks stored in the memory of the inverter control card and bysetting the parameters. This can be done by means of the control panel

pushbuttons.

55


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6.2 Common DC-bus drive and sectional drive control

The control panel may also be connected to a more extensive computer-controlled system. Figure 6.4 shows the block diagram of such a system.

F0

START

STOP

+

-

F1

F2

F3

PAR

CTRL

RESET

CONTROL PANEL

~M

3~

DRIVENo1

DRIVENo2

DRIVENo3

Figure 6.4. Block diagram of a common DC-bus drive or a sectional drive.

(EN 5709 7469)

In sectional drives or in common DC-bus drives, the control panel keys may beused by a separate computer. The computer then operates on a higherhierarchical level than the control panel. This reduces cabling costs and thefunctions of the control panel keys are easy to change during commissioningby modifying the master computer program.

56


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7. DRIVE APPLICATIONS

The modules of the SAMI STAR frequency converter are used to implementvarious drive applications. The three most common of these applications are

described below.

7.1 Single drive

The single drive is the most common of the frequency converter applications. A frequency converter drive is called a single drive when it consists of aseparate power supply and one inverter unit which supplies one motor orseveral motors.

Figure 7.1 shows the block diagram of a single drive, including contactor unit

SAFUL, line converter unit SAFUC, capacitor bank unit SAFUB, and inverterunit SAFUI. The drive is controlled by means of SAMI STAR control panelSAFP 11 PAN.

I/U

I/U

I/U

CP1

I/O

V1

µP

V6

U2

V2

W2

V1 V2 V3

V4 V5 V6

M

3~

A HzCP2

SAFUL SAFUC SAFUB SAFUI

U1

V1

W1

3 ~

IN

Figure 7.1. Block diagram of a single drive. (5709 5199)

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7.2 Common DC-bus drive

A common DC-bus drive is a combination of several single drives, with ashared contactor unit, line converter unit and capacitor bank unit.

CTU LCU

CBU

M

3~

M

3~

M

3~

INU INU INU

3~

AC IN

Dc Bus

(L+, L-)

CP1 CP1 CP1

drive

sectionsupply section

Figure 7.2. Block diagram of a common DC-bus drive. (EN 5709 7426)

The inverter units of a common DC-bus drive are connected to the capacitorbank unit through fuse switches and the DC bus. The control principle is thesame as in single drives.

Figure 7.3. Block diagram of the inverter unit (SAFUI) of a common DC-busdrive. (5709 7400)

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7.2.1 DC bus

Figure 7.2 shows that when several frequency converters are placed in thesame electrical equipment room, only the SAFUIs are needed as separateunits for each frequency converter, while the SAFUL, the SAFUC and theSAFUB may be shared by all frequency converters of the drive.

A feature fundamental to the design of the SAMI STAR frequency converter isthe common DC bus, which brings the following benefits:

- braking power is freely conducted from one inverter to another via the DCbus,

- total number of components is reduced,- load current on the DC capacitor bank is reduced,- costs are reduced,

- suppression of interferences to and from the AC mains is easier.

Since the inductance of the DC bus must be an order smaller than theinductance of the di/dt choke of the inverter units, the normal AC busbarscannot be used. The required small leakage inductance is achieved whenthin, broad busbars are used pressed against each other and plastic insulationis inserted between the busbars.

The DC bus is located in the upper part of the cabinets and the inverter isconnected to the bus through a disconnector.

A common DC bus can naturally be used for the supply of different sections ofone machine (paper machine, winder, barking line, bandsaw line). It is alsoapplicable when several frequency converters are placed in the sameelectrical equipment room.

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7.3 Sectional drive

In a sectional drive (e.g. a paper machine), each section has its own inverterunit SAFUI, while the SAFUL, the SAFUC and the SAFUB are shared by thewhole line.

CTU LCU

CBU

M

3~

M

3~

M

3~

INU INU INU

3~

AC IN

Dc Bus

(L+, L-)

CP2 CP2 CP2

drive

sectionsupply section

SELMA 2

Figure 7.4. Block diagram of a sectional drive. (EN 5709 7434)

Each SAFUI is connected to the DC bus through a fuse isolator (see figure7.3). The emergency-stop command of the drive controls the main contactorof the contactor unit. A motor-specific safety switch, if required, may be fittedbetween the motor and the inverter unit.

The whole sectional drive is controlled by a computer (e.g. SELMA 2) with aduplex, point-to-point serial communication link to the control panel of eachsection. The control panel CP2 (SAFP 21 PAN) is the operating and displaystation of the section concerned.

53515487 sami star functional description

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