Extensive use of power electronics-controlled induction motor drives over the past few decades has enabled the development of loss minimization control algorithms. With the technological advancements in power semiconductor switching devices such as insulated gate bipolar transistors and gate commutated thyristors, induction motor drives are increasingly used in applications, ranging from automotive traction to more-electric aircraft, which have widely varying speed, torque and power requirements.
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MathWorks does not warrant, and disclaims all liability for, the accuracy, suitability, or fitness for purpose of the translation. This motor has a three-phase winding at the stator and a wound rotor or a squirrel-cage rotor.
The squirrel-cage rotor consists of slots of conducting bars embedded in the rotor iron. The conducting bars are short-circuited together at each end of the rotor by conducting rings. The AC5 model is based on a wound rotor synchronous motor, and the AC6 model uses a permanent magnet synchronous motor.
The models of these three types of motors are available in the Machines library. These AC motors are fed by a variable AC voltage and frequency produced by an inverter. The type of inverter used in the six AC drive models is a voltage source inverter VSI in the sense that this inverter is fed by a constant DC voltage.
This constant voltage is provided by an uncontrolled diode rectifier and a capacitor capacitive DC bus voltage. Dynamic Braking When the DC bus is provided by a diode rectifier, the drive doesn't have a bidirectional power flow capability and therefore cannot perform regenerative braking.
This braking scheme is called dynamic braking. It is placed in parallel with the DC bus in order to prevent its voltage from increasing when the motor decelerates. With dynamic braking, the kinetic energy of the motor-load system is converted into heat dissipated in the braking resistor.
Modulation Techniques The VSI inverters used in the AC drive models of the library are based on two types of modulation, hysteresis modulation and space vector pulse width modulation PWM.
The hysteresis modulation is a feedback current cont rol method where the motor current tracks the reference current within a hysteresis band. The following figure shows the operation principle of the hysteresis modulation.
The controller generates the sinusoidal reference current of desired magnitude and frequency that is compared with the actual motor line current.
If the current exceeds the upper limit of the hysteresis band, the upper switch of the inverter arm is turned off and the lower switch is turned on.
As a result, the current starts to decay. If the current crosses the lower limit of the hysteresis band, the lower switch of the inverter arm is turned off and the upper switch is turned on. As a result, the current gets back into the hysteresis band. Hence, the actual current is forced to track the reference current within the hysteresis band.
Next figure shows the hysteresis current control modulation scheme, consisting of three hysteresis comparators, one for each phase. The space vector modulation technique differs from the hysteresis modulation in that there are not separate comparators used for each of the three phases.
Instead, a reference voltage space vector Vs is produced as a whole, sampled at a fixed frequency, and then constructed through adequate timing of adjacent nonzero inverter voltage space vectors V1 to V6 and the zero voltage space vectors V0, V7.
A simplified diagram of a VSI inverter is shown below. In this diagram, the conduction state of the three legs of the inverter is represented by three logic variables, SA, SB, and SC.
A logical 1 means that the upper switch is conducting and logical 0 means that the lower switch is conducting.
A logical 1 means that the upper switch is ON and logical 0 means that the lower switch is ON. The switching states and the corresponding phase to neutral voltages are summarized in the table that lists states, inverter operations, and space voltage vectors.
The six active vectors are an angle of 60 degrees apart and describe a hexagon boundary. The two zero vectors are at the origin. As an example, for the location of the Vs vector shown in the diagram of the inverter space-vector voltage, the way to generate the inverter output is to use the adjacent vectors V1 and V2 on a part-time basis to satisfy the average output demand.
The voltage Vs can be resolved as:6 I. INTRODUCTION HIS document describes the design road taken when looking at a 3-phase Variable Frequency Drive (VFD). These motor drives are designed to be used in conjunction with a 3-phase induction motor.
The Development of a Digital Controller for a Three-Phase Induction Motor by Sridhar Chakravarthy Venkatesh Submitted to the Department of Electrical Engineering and Computer Science. Abstract This thesis considers robust control of an induction motor drive, consisting of an input filter, a voltage source inverter and one or several induction motors in.
Vector Control of an Induction Motor based on a DSP QIAN CHENG LEI YUAN Department of Energy and Environment Division of Electric Power Engineering Chalmers University of Technology Abstract In this thesis project, a vector control system for an induction motor is implemented on an evaluation board.
By comparing the pros and cons of eight. CURRENT MEASUREMENT IN POWER ELECTRONIC AND MOTOR DRIVE APPLICATIONS – A COMPREHENSIVE STUDY by ASHABEN MEHUL PATEL A THESIS Presented to the Faculty of the Graduate School of the.
simulation and speed control of induction motor drives a thesis submitted in partial fulfilment of the requirements for the degree of bachelor of technology in.