High Performance Control of AC Drives with Matlab / Simulink Models

9.11 Questions

Q1. Why does the common mode voltage appears in PWM voltage inverters?

A1. The common mode voltage is inherent for PWM voltage inverters. It is the result of transistors switching sequence. It should be explained by the analysis of zero voltage components for each voltage vector, as presented in Table 9.2.

Q2. Explain the bearing current phenomena.

A2. The bearing current phenomena are explained in Section 9.4.

Q3. Why is the differential mode filter used?

A3. The main purpose of the differential mode filter use is to obtain the sinusoidal motor supply voltage. As the result of the supply voltage shape improvement, the motor has greater efficiency, is less noisy, and the disturbance level is decreased.

Q4. Which type of filter is correct for bearing current limitation?

A4. The common mode filter limits the common mode current and bearing currents.

Q5. Specify the method for motor protection in the drive with a voltage inverter.

A5. This is explained in Section 9.5 and Table 9.3.

Q6. Describe the design process of the differential mode filter.

A6. The design process is presented in Section 9.61.

Q7. Describe the design process of the common mode filter.

A7. The design process is presented in Section 9.61.

Q8. Sketch the structure of the common mode choke. Where should the CM choke be installed?

A8. The structure of the common mode choke is presented in Figure 9.13, with a description given is Section 9.5.1. The CM choke is installed on the output of the voltage inverter? ...