Control of Electric Induction Drives

Introduction

Both classic industrial production tasks (e.g., metal processing) and the automation challenges for the energy transition (e.g., electric vehicles and wind turbines) require motors and generators to be able to achieve wide torque and speed ranges due to working conditions that are heavily dependent on the work cycle, landscape, and weather conditions. The transition processes between the stationary operating points must also often be highly dynamic and precise at the same time. To achieve the required dynamics, the electric machines are powered with inverters featuring integrated sensors and programmed control loops.·Together, the selected controller structure and settings, the accuracy of the parameter settings, the sensitivity of the sensors, and the characteristics of the semiconductors in the inverter determine the accuracy, reliability, efficiency, and speed of the drive.

Target Audience

Developers of electric machines and drive systems.

Main Topics

• Transient models of a permanent magnet synchronous machine and an induction machine in the dq and xy coordinate systems: concept of co-rotating coordinate systems, key machine parameters and time constants, applicability limits due to neglected second-order electromagnetic effects 
• Electric inverter design and operation: semiconductor behavior, commutation processes and control, DC link voltage and output voltage, pulse width modulation, and space vector modulation
• Drive structure with field-oriented control: block diagram with transfer functions, controllers, sensor feedback, non-linearity
• Influence of the controller structure and settings as well as sensors on the overall dynamics of the electric drive (speed, stability, vibration behavior, and accuracy): PI/PID controllers, cascade control, encoders and resolvers, sensorless control and monitoring, reactions to machine parameter changes (e.g., due to temperature) and spontaneous excitations (e.g., faults) from the power supply or the mechanical system 
• Overview of other (non-inverter-fed) drive and control systems: electronically commutated small motors, control of stepper motors, synchronous generator excitation system 

Objectives

Participants will gain knowledge of the structure, operating modes, and key development concepts of electrical drive systems, with a focus on converter-fed induction machines and permanent magnet synchronous machines with field-oriented control. Explanations are illustrated with detailed time curves (the results of transient simulations) for currents, voltages, speed, and torque.

Instructors

Olga Korolova

ProFluxx GmbH
www.profluxx.com