The aim of the course is to provide the student with the methods for controlling power converters and electric drives by means of digital controllers (Digital Signal Processors).

Time-discretization of dynamic models
Real-time digital control
Floating-point and fixed point firmware implementation
Simulation of the control code
Fundamentals of parametric identification for motors and power converters
Experimental implementation and test of the firmware
Production of a technical report

Modeling of electric motors and of power converters
Fundamentals of continuous-time and discrete time control
Fundamentals of Matlab/Simulink simulation
C-programming and fundamentals of Matlab-programming

1) Introduction to Digital Control (10 hours)
' Finite Differences, z-transform, digital systems stability.
' Discretization of transfer functions and of the state-equations of linear systems.
' Digital implementation of elementary components: 1st order low-pass filter, PI regulator, etc..

2) Digital Signal Processors (DSP) for industry applications (10 hours)
' Architecture of microcontrollers and DSPs
' 8-bit microcontrollers: the PIC microcontroller
' modern DSPs for motion control
' Fixed-point implementation of control algorithms
' Fundamentals of DSP-fixed-point-programming: C and Assembler languages and examples.
' Development tools for DSPs.

3) DSP to electric drive interfacing (10 hours)
' Outline of the Electrical Drive (inverter ' motor ' control board).
' Analog signal conditioning
' Digital signal conditioning, inverter swicthing signals generation.
' Current measurement: type of transducers, sampling techniques.
' Shaft position and speed measurement: type of transducers, measure techniques.
' Other measures (voltage, temperature, etc')
' Communication protocols (JTAG, CAN, SPI)

4) Experimental implementation (30 hours)

a) S-Function based simulation
' implementation of the control code in ANSI-C
' Portability of the simulated code towards different digital controller

b) Closed-loop current control of DC/DC converters
' Buck converter, boost converter, bi-directional converter
' Floating point and fixed point implementation

c) Vector control of the Induction Motor (IM)
' PWM modulation, common mode injection
' Scalar control (V/Hz)
' Current control in the synchronous reference frame (d,q)
' Rotor flux observers
' Field Oriented Control
' Field-weakening control
' Floating point and fixed point implementation

b) Vector control of permanent magnet synchronous motors.
' Control scheme of the surface mounted PM (SPM) motor and comparison with the IM scheme
' Control scheme of the interior PM (IPM) motor and comparison with the IM scheme
' Flux observer in the stator reference frame
' Vector Control
' Flux-weakening of SPM and IPM motors
' Floating point and fixed point implementation

In addition to lectures, the course programme includes laboratory activities:
- Simulink laboratory: simulation of the control algorithms (8 hours)
- DSPACE laboratory: floating point implementation of the control algorithms (10 hours)
- DSP laboratory: fixed-point implementation of the control algorithms (12 hours)

Class notes
G.Ellis, 'Control System Design Guide', 2000, Academic Press.
R. Isermann, 'Digital control systems', 1989, Springer.
Vagati, 'Electrical drives', class notes.
Fratta, 'Dispense del corso di conversione statica dell'energia elettrica' (in Italian)

Assigned project 1 ' Implementation of a digital control in simulation
Assigned project 2 ' Experimental implementation of a digital control
Oral exam: based on the discussion of the two assigned project