10-10-2012, 05:08 PM
DSP Based Electric Drives Laboratory
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Introduction
There are four major components of the DSP-based electric-drives system, which will be used to
perform all the experiments in this course. They are as follows: 1) Motor coupling system,
2) Power Electronics Drives Board, 3) DSP based DS1104 R&D controller card and CP 1104 I/O
board and 4) MATLAB Simulink and Control-desk. In this experiment, you will be briefly
introduced to the role of above mentioned four components in the DSP-based electric-drives
system. An example of speed-control of a DC-motor will be demonstrated. The Simulink file and
Control-desk layout will be supplied to perform this experiment. The communication between the
four components will be explained while controlling the speed of the motor. Section 1.2 details the
DSP-based electric-drives system vis-à-vis the role of the four components listed above. In Section
1.3 a step-by-step procedure to run the DC motor speed-control will be performed.
DSP-based electric-drives system
DSP-based electric-drives system.
• Motor coupling system: This system contains the motor that needs to be characterized or
controlled. The system has a mechanical coupling arrangement to couple two electric
machines. The motor under test (MUT) whose speed/torque needs to be controlled, could be
either a DC motor or a Three-phase induction motor or a Three-phase Permanent-Magnet AC
(PMAC) motor. The system also has an encoder mounted on the machine which is used to
measure the speed of the MUT. This can be used for close loop feedback speed-control of the
motor.
Demonstration of Speed Control of a DC motor
The system for the speed-control of a DC motor is shown in Fig 1.3. Note that the currA1 (i.e.
phase-current of DC motor) and encoder signal (speed of DC motor) is fed back to the DS1104
board via CP 1104. The requirement of feeding back phase-current and speed of the motor will be
studied in experiment-4. For now, assume that these two quantities are required to control the
speed of DC motor. Perform the following steps to run the experiment. The communication
between the four components (explained in section 1.2) is detailed in each step, wherever
necessary.
Switching Power-Pole Building Block
The switching power-pole building block has been explained in Section 1-6-1 of [1]. Depending on
the position of the bi-positional switch, the output pole-voltage vA is either Vin or 0. The output
pole-voltage of the power-pole is a switching waveform whose value alternates between Vin and 0
depending on the pole switching functionqA .