Alternating Current and Open-loop Voltage Controller Essay

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Pages: 3

Nghia Dam, Thinh Duong
ECE 6671
Lab 3
TA: Zachary Beus


For this lab, we are going to be using Simulink and dSPACE Control-Desk to measure the real and reactive powers of a single RL load, and observe its resistance and reactance. In the second part of this lab, we will design an open-loop voltage controller that will allow us the control over the speed of a DC generator.

For this Lab, the equipment required is the following: dSPACE I/O box #1
PEDB with ribbon cable and +12V supply #3
AC Induction Motor (SCIG) #2
DC Generator (DCG), frame mounted, with coupler #1
Box of Cables
To start off, we designed a Simulink Model that’s capable of measuring the real, reactive and apparent power consumed by the generator. We started by building a model that can generate an AC voltage. We followed Figure 2 and added a Digital to Analog Channel block, from lab 1. Then we added an Inverter Board Control Function blocks to stop/start and reset the board.

Figure 1. Simulink model to generate AC voltage
Before we connected the SCIG to PEDB, we measured the resistance between two phases.

We then compared the measured value and the motor resistance and saw that they were relatively the same.

Next we modified our Simulink model with the above equations and set up the hardware, by referencing to lab 1. Using dSPACE, we applied 1 Vpeak to the windings, and measure the line-to-line current and powers at 60-Hertz frequency. We then made some modification and measured the resistance, reactance, and inductance of the AC induction generator, which are all shown below. Our Simulink model is shown in Figure 2.

Figure 2. Simulink model of Part 2.1

RMS Current (A)
RMS Voltage (V)
Real Power (W)
Reactive Power (VAR)
Apparent Power (VA)
Resistance ()
Reactance ()
Inductance (mH)

For this next part of the lab, we are to design an open-loop controller in Simulink to control the speed of the DC generator. We were able to reuse lab 1’s Simulink model for this part by making some minor modification, as shown in figure 3. We then design a Control-Desk layout in dSPACE to take the measurements of current, velocity and position of the DC motor as they change. We also added the Stop/Start, Reset and Zero Encoder command, and added the ability to read the data from the encoder and current of the motor. As a precaution, we made sure that the encoder is measuring the position and velocity by rotating the DC motor shaft, and saw that it was working. We then apply steps of