ecet 211 electric machines & controls lecture 9-1...

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ECET 211 Electric Machines & Controls

Lecture 9-1

Adjustable-Speed Drives and PLC Installations

(1 of 2)

Text Book: Electric Motors and Control Systems, by Frank D. Petruzella, published by McGraw Hill, 2015.

Paul I-Hai Lin, Professor of Electrical and Computer Engineering Technology

P.E. States of Indiana & California

Dept. of Computer, Electrical and Information Technology

Purdue University Fort Wayne Campus

Prof. Paul Lin

Lecture 9-1 Adjustable-Speed Drives and PLC Installations (1 of 2)

A Quick Overview of Motor Control Electronics (Chapter 9)

• Diodes, Transistors, Thyristorsand ICs

Part 1. AC Motor Drive Fundamentals

• Variable-Frequency Drives (VFD)

• Volts per Hertz Drive

• Flux Vector Drive

Part 2. VFD Installation and Programming

• Parameters

• Selecting the Drive

• Lines and Load Reactors

• Location

• Enclosures

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• Mounting Techniques

• Operator Interface

• Electromagnetic Interference

• Grounding

• Bypass Contactor

• Disconnecting Means

• Motor Protection

• Braking

• Ramping

• Control Inputs and Outputs

• Motor Nameplate Data

• Derating

• Types of Variable-Frequency Drives

• PID control

• Parameter Programming

• Diagnostics and Troubleshooting

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Lecture 9-1 Adjustable-Speed Drives and PLC Installations

Part 3. DC Motor Drive Fundamentals (SKIP)

• Applications

• DC Drives – Principles of Operation

• Single-Phase Input – DC Drive

• Three-Phase Input – DC Drive

• Field Voltage Control

• Non-regenerative and Regenerative DC Drives

• Parameter Programming

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Part 4. Programmable Logic Controllers (PLCs)

• PLC Sections and Configurations

• Ladder Logic Programming

• Programming Timers

• Programming Counters



Semiconductor Didoes• Rectifier Diode

• Zener Diode

• Light-Emitting Diode

• Photodiodes

Transistors

Thyristors

ICs

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Semiconductor Didoes: Rectifier Diode, Zener Diode, Light-Emitting Diode

• Photodiodes

Figure 9-1 PN-Junction Diode

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Figure 9-2 Diode forward and reverse biasing


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Figure 9-3 Single-phase, half-wave rectifier circuit

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Figure 9-5 Single-phase, full-wave rectifier circuit

Figure 9-7 Three-phase, full-bridge rectifier


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Figure 9-6 Capacitor filter

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Transistors

Bipolar Junction Transistor (BJT)

Figure 9-14 Bipolar junction transistor

Figure 9-16 BJT switching of an AC load


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Transistors

Figure 9-18 Phototransistor employed as part of an optical isolator found in a programmable logic controller (PLC) AC input module circuit

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Insulated-Gate Bipolar Transistor (IGBT)

Figure 9-26 Insulated-gate BJT – N type

Figure 9-27 IGBT power module


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Figure 9-28 IGBT used in an electronic motor drive

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TRIAC

Figure 9-35 Triac

Figure 9-36 Triac switching circuit


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TRIAC

Figure 9-37 Triac switching of PLC output module

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The two most important technologies associated with motor control are

• Adjustable speed drives

• Programmable logic controller

Part 1. AC Motor Drive Fundamentals

Primary function of any electronic Adjustable-Speed Drive is to control

• Speed

• Torque

• Acceleration

• Deceleration, and

• Direction of rotation

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Lecture 9-1 (Ch 10) Adjustable-Speed Drives and PLC Installations

Figure 10-1 Variable-speed AC motor drive used for lower-power applications

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Figure 10-2 Block diagram of a typical three-phase VFD

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Figure 10-3 Three-phase and single-phase converter input connections

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Figure 10-4 Inductor and capacitor connections within the DC bus

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Figure 10-5 Typical VFD voltage measurement

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Figure 10-6 The three sections of a variable-speed drive

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Figure 10-7 Simplified circuit of a PWM inverter

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Figure 10-7 Simplified circuit of a PWM inverter

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Figure 10-8 IGBT switch element


Figure 10-9 Sine-wave line voltage superimposed on the PWM inverter output

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Figure 10-10 Inverter motor and control

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Open Loop vs Closed Loop Control Figure 10-11 Closed-loop control system

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Volts per Hertz Drive (for AC IM) V/Hz = Voltage/Frequency

• An Example: V = 460 volts, F = 60 Hz

• V/Hz = 7.67 apply to any frequency between 0 and 60 Hz

Control principle:

• To maintain constant magnetic flux in the motor, the terminal voltage magnitude must increase roughly to the applied voltage

Horsepower = Torque x Speed x k

• With other refinements:

Low-frequency voltage boost

Steady-state slip compensation

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Flux Vector Hertz Drive (for AC IM) A vector quantity has both

magnitude and direction

A Flux vector drive controls both the magnitude and direction of the magnetic flux in an AC induction motor.

Figure 10-13 Vector Drives control both magnitude and direction of the magnetic flux

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Flux Vector Hertz Drive (for AC IM) Figure 10-14 Sensorless vector control drive block diagram

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Flux Vector Hertz Drive (for AC IM) Figure 10-15 Flux vector drive and encoder

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Summary & Conclusion

Questions?

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ecet 211 electric machines & controls lecture 9-1...

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