# 88217 - Electric Drives P

• Docente: Luca Zarri
• Credits: 6
• SSD: ING-IND/32
• Language: Italian
• Campus: Bologna
• Corso: First cycle degree programme (L) in Mechatronics (cod. 5818)

Also valid for First cycle degree programme (L) in Mechatronics (cod. 6009)
• from Sep 18, 2023 to Dec 20, 2023

## Learning outcomes

At the end of the course, the student knows:

• the general methodologies to understand the performance and control of electrical machines and drives
• the fundamentals of the electrical machines, from circuit behavior to electromagnetic torque production, and the basic equations of the physical phenomena
• the mathematical models of electrical machines, which are valid for steady-state and transient analysis
• how to model and simulate dc motor drives, permanent magnet brushless motor drives, induction motor drives, and stepper motors.

## Course contents

Introduction and basic principles of energy conversion

Force on current-carrying conductors. Voltage induced in a moving conductor. Magnetic materials. Magnetic circuits. Coupled coils. Coefficient of coupling. Self and mutual inductances. Voltage equations. Stored energy in the magnetic field. Fundamentals of electromechanical energy conversion and torque production. Types of electrical machines.

DC motor drives

Separately-excited DC machines. Mathematical model. Steady state characteristics, and control of the armature and field currents. Control of DC motors in the constant-torque speed region and in the field-weakening region. Transition from motoring to braking operation. DC drives with force-commutated converters. Single-, double-, and four-quadrant operation. Constant-torque and constant-power operation.

Dynamic model of a DC machine. Dynamic behavior of DC motors with constant flux. Block diagram of a DC motor coupled with a mechanical load. Torque production and control. Closed-loop control of torque and speed. Field weakening. Starting and speed reversal transients. Application to DC motor drives.

Brushless DC motor drives

Analysis of the magnetic circuit. Torque and back-emf equations. Winding inductances and armature reaction. Torque/speed characteristics: performance and efficiency. Three-phase brushless DC motor. Position sensors. Drive characteristics and control principles. Application of brushless DC motor drives.

Variable frequency synchronous motor drives

Magnetic circuit analysis of synchronous machines. Synchronous reactances (d-, q-axis). Torque and machine equations. Steady-state characteristics. Open-loop control of voltage source inverter drives. Starting performance by squirrel gage rotors. Closed-loop control of current controlled PWM inverter drives. Applications.

Brushless AC motor drives

Dynamic model of permanent magnet synchronous machines with surface mounted magnets. The dq machine and flux equations. Principles of field orientation. Torque production and control. Dynamic model of permanent magnet synchronous machines with interior magnets. The dq machine and flux equations. Torque production and control. Control of the synchronous machine supplied by current controlled PWM inverter. Simulation of electromechanical transients. Maximum torque capability of the machine in the flux weakening region.

Induction motor drives

Analysis of induction motors based on steady-state machine model. Torque and machine equations. Steady-state characteristics. Starting of induction motors. Constant terminal volts/hertz operation. Torque characteristics. Low-frequency performance with increased volts/hertz. Constant air-gap flux operation. Torque characteristics. Current-source inverter drive with slip frequency control. Current controlled PWM inverter drive with slip frequency control. Constant-horsepower operation. Dynamic model of induction machines. The dq machine and flux equations. Torque equation. Principles of field orientation. Machine equations and torque in the rotor flux oriented reference frame. Decoupling control of flux and torque in the rotor flux oriented reference frame. Flux models. Direct scheme and indirect scheme of induction motor field oriented control. Control of the induction machine supplied by current controlled PWM inverter. Simulation of electromechanical transients. Maximum torque capability of the machine in the flux weakening region. Applications.

Stepper Motors

Reluctance torque. Fundamentals of stepper motors. Design of a stepper motor. Torque characteristics. Stability region and behavior at high speed. Power converters for stepper motors.

• I. Boldea, S. A. Nasar: ELECTRIC DRIVES, CRC Press, New York.
• P. Vas: VECTOR CONTROL of AC MACHINES, Oxford University Press, New York.
• T.J.E. Miller: SWITCHED RELUCTANCE MOTORS AND THEIR CONTROL. Clarendon Press, Oxford.
• Bimal Bose: MODERN POWER ELECTRONICS AND AC DRIVES, Prentice-Hall.
• Takashi Kenjo: STEPPING MOTORS AND THEIR MICROPROCESSOR CONTROLS, Clarendon Press, Oxford, 1985.

## Teaching methods

The theoretical explanations are completed with the solutions to numerical problems and some laboratory experiences.

The teaching language is ITALIAN.

## Assessment methods

The exam consists of a written test, an oral test (on request) and a discussion of the reports relating to laboratory experiences. It is also possible to investigate additional aspects related to an electric drive (optional).

## Teaching tools

Powerpoint slides used for lecturing and basic mathematical models of electrical drives for numerical simulations are available.

The password will be given by the professor at the beginning of the lessons.

## Office hours

See the website of Luca Zarri