accessories for frequency inverter 1dd65

8/9/2019 Accessories for Frequency Inverter 1dd65

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Shenzhen KCLY Electric Co., Ltd

www.kcly.net.cn

Introduction of Variable Frequency Drive (VFD)

CONTENTNames 1

The technology parts of an AC drive 1

A variable frequency drive system 2

The benefits of using a variable frequency VFD 3

Applications and example 4

Applications 4

Example of driving pumes 5

Service and product of KCLY Electric 5

CMT303 Vector Sensorless Frequency Inverter Series: 6

Contact information 7

Names

Frequency inverter, frequency converter, frequency changer, AC drives, VSD

(varibale speed drives), VFD (variable frequency drives), ASD, AFD, ...

A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric

motor by controlling the frequency of the electrical power supplied to the motor. A variable frequency drive is a specific type of

adjustable-speed drive (ASD). Variable-frequency drives are also known as adjustable-frequency drives (AFD),

variable-speed drives (VSD), variable-frequency drives (VFD), frequency changer, frequency converter, frequency inverter

( thats what we call it commonly in China), AC drives, microdrives or inverter drives. Since the voltage is varied along with

frequency, these are sometimes also called VVVF (variable voltage variable frequency) drives.

The technology parts of an AC drive

The speed is controlled by changing the frequency of the electrical supply to the motor. The 3-phase voltage in the

national electrical grid connected to a motor creates a rotating magnetic field in it. The rotor of the electrical motor will follow


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this rotating magnetic field. An AC drive converts the frequency of the network to anything between 0 to 300 Hz or even higher,

and thus controls the speed of motor proportionally to the frequency.

1. Rectifier unit

The AC drive is supplied by the electrical network via a rectifier. The rectifier unit can be uni- or bidirectional. When

unidirectional, the AC drive can accelerate and run the motor by taking energy from the network. If bidirectional, the AC drive

can also take the mechanical rotation energy from the motor and process and feed it back to the electrical network.

2. DC circuit

The DC circuit will store the electrical energy from the rectifier for the inverter to use. In most cases, the energy is stored

in high-power capacitors.

3. Inverter unit

The inverter unit takes the electrical energy from the DC circuit and supplies it to the motor. The inverter uses modulation

techniques to create the needed 3-phase AC voltage output for the motor. The frequency can be adjusted to match the need

of the process. The higher the frequency of the output voltage is, the higher the speed of the motor, and thus, the output of the

process.

A variable frequency drive system

A variable frequency drive system generally consists of an AC motor, a controller and an operator interface.

VFD motor

The motor used in a VFD system is usually a three-phase induction motor. Some types of single-phase motors can be

used, but three-phase motors are usually preferred. Various types of synchronous motors offer advantages in some situations,

but induction motors are suitable for most purposes and are generally the most economical choice. Motors that are designed

for fixed-speed operation are often used. Certain enhancements to the standard motor designs offer higher reliability and

better VFD performance.

VFD controller


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Variable frequency drive controllers are solid state electronic power conversion devices. The usual design first converts

AC input power to DC intermediate power using a rectifier or converter bridge. The rectifier is usually a three-phase,

full-wave-diode bridge. The DC intermediate power is then converted to quasi-sinusoidal AC power using an inverter switching

circuit. The inverter circuit is probably the most important section of the VFD, changing DC energy into three channels of AC

energy that can be used by an AC motor. These units provide improved power factor, less harmonic distortion, and low

sensitivity to the incoming phase sequencing than older phase controlled converter VFD's. Since incoming power is converted

to DC, many units will accept single-phase as well as three-phase input power (acting as a phase converter as well as a speed

controller); however the unit must be derated when using single phase input as only part of the rectifier bridge is carrying the

connected load.

As new types of semiconductor switches have been introduced, these have promptly been applied to inverter circuits at

all voltage and current ratings for which suitable devices are available. Introduced in the 1980s, the insulated-gate bipolar

transistor (IGBT) became the device used in most VFD inverter circuits in the first decade of the 21st century

VFD operator interface

The operator interface, also commonly known as an Human Machine Interface (HMI), provides a means for an operator

to start and stop the motor and adjust the operating speed. Additional operator control functions might include reversing and

switching between manual speed adjustment and automatic control from an external process control signal. The operator

interface often includes an alphanumeric display and/or indication lights and meters to provide information about the operation

of the drive. An operator interface keypad and display unit is often provided on the front of the VFD controller as shown in the

photograph above. The keypad display can often be cable-connected and mounted a short distance from the VFD controller.

Most are also provided with input and output (I/O) terminals for connecting pushbuttons, switches and other operator interface

devices or control signals. A serial communications port is also often available to allow the VFD to be configured, adjusted,

monitored and controlled using a computer.

The benefits of using a variable frequency VFD

The types of motors that VFD control are normally operating at constant speed. Enabling the user to control the speed of

motor potentially gives him various benefits in terms of process control, system stress and energy savings.

Adjusting speed as a means of controlling a process

Smoother operation

Acceleration control

Different operating speed for each process

Compensate for changing process variables

Allow slow operation for setup purposes

Adjust the rate of production

Allow accurate positioning

Control torque or tension

Reducing the start-up current, which allows use of smaller fuses and supply connections and reduces peak loads on the

electrical network

Reducing the mechanical shock in start and stop situations

Smooth ramp up and ramp down causes less stress to the mechanics of fans and pumps and to air ducts and water

piping

Slowing down the speed rather than damping the output will result in lower noise levels

Tuning the HVAC system during and after the commissioning is easier when the flexibility of an AC drive is used

Reduced number of starts and stops reduces the wear of the compressor


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The piping and mechanics are stressed less in ramp up or down situations

Reduced noise level in low load situations

Possibility to use high speed compressors

Saving energy by using AC drives

An VFD often uses less energy than an alternative fixed speed mode of operation. Fans and pumps are the most

common energy saving applications. In these applications, energy savings are typically 20-50%.

Applications and example

Applications

Aside from the obvious application of converting bulk amounts of power from one distribution standard to another,

frequency changers are also used to control the speed and the torque of AC motors. In this application, the most typical

frequency converter topology is the three-phase two-level voltage source inverter. The phase voltages are controlled using the

power semiconductor switches and pulse width modulation (PWM). Semiconductor switching devices and anti-parallel

connected freewheeling diodes form a bridge, which can connect each motor phase to the positive or negative dc-link

potential. The PWM changes the connections of the phases between the positive and the negative dc-link potentials so that

the fundamental wave voltage has the desired frequency and amplitude. The motor reacts primarily to the fundamental

voltage and filters out the effects of the harmonic voltages.

Another application is in the aerospace and airline industries. Often airplanes use 400 Hz power so 50 Hz or 60 Hz to

400 Hz frequency converter is needed for use in the ground power unit used to power the airplane while it is on the ground.

In renewable energy systems, frequency converters are an essential component of doubly fed induction generators

(DFIGs) as used in modern multi-megawatt class wind turbines .

Frequency changers are typically used to control the speed of pumps and fans. In many applications significant energy

savings are achieved. The most demanding application areas are found on the industrial processing lines, where the control

accuracy requirements can be very high.

An HVDC-system can serve as frequency converter for large loads.

Typical applications are list below:

Motor, Blowers, Fans, Paper process, Rolling machine tools, Food process and other industry application sucha as

water pump, air compressor, air condition, packing machine, Ceramic ballmill, Textile machine, Industrial washing machine,

Plastic injection machine, Wooden machine.STS (SHIP-TO-SHORE CRANE), RMG, gantry crane, lading machine, unloading

machine, dumper, big tonnage crane-bridge and gate, crane for mine, conveyer, rolling mill of multi-motors, hoister for blast

furnace, centrifuge, pouring washer, segment drive for paper machine, centrifugal casting machine, large punch machine.


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Example of driving pumes

An adjustable speed drive can often provide smoother operation compared to an alternative fixed speed mode of

operation. For example, in a sewage lift station sewage usually flows through sewer pipes under the force of gravity to a wet

well location. From there it is pumped up to a treatment process. When fixed speed pumps are used, the pumps are set to

start when the level of the liquid in the wet well reaches some high point and stop when the level has been reduced to a low

point. Cycling the pumps on and off results in frequent high surges of electrical current to start the motors resulting in

electromagnetic and thermal stresses in the motors and power control equipment, the pumps and pipes are subjected to

mechanical and hydraulic stresses, and the sewage treatment process is forced to accommodate surges in the flow of sewage

through the process. When adjustable speed drives are used, the pumps operate continuously at a speed that increases as

the wet well level increases. This matches the outflow to the average inflow and provides a much smoother operation of the

process.

Service and product of KCLY Electric

Shenzhen KCLY Electirc Co., Ltd. was established at 2004, who has been focus on VFD for more than 5 years. We offer

solutions basic on actually problem you face with you factory. For now, our sensorless vector control frequecy inverter for

general use, CMT303 series, is popular among clients overseas, mainly from Southeast Asia, Middle East, Afica and South

America. Its high performance and competitive price build up the main reasons. Besids, the CMT308 series used in special

industries like Plastic Injection, Textile.

CM2000E series


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Energy saving operation function to increase motor power factor and efficecy tolimit

Standard internal PG card assisting external PG to realize V/F with PG speed closed-loop control

Double protection of system and unit, sequential control when power on, gate control and automatically save

before faulty

Sine wave regenerative braking unit to save the energy and protect environment

Master-slave function can realize the power equilibrium and speed synchronization

Contact information

Ctc: Anky Co

Shenzhen KCLY Electric Co.,Ltd.

Address:Room C05, 4th Floor, international fair plaza,Baoan north Road,lovo District Shenzhen,China

Http://www.kcly.net.cn

http://kcly.en.alibaba.com/

Tel :+86-755-82407847

Fax :+86-755-82426031

Mobile: +86-15013789010

Email:[email protected]; [email protected]

MSN:[email protected]

Skype: anky_co

Yahoo Messenger: [email protected]
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accessories for frequency inverter 1dd65

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