Power semiconductors

How many switching devices does a typical three-phase inverter for driving a three-phase motor use?

  1. A3
  2. B6
  3. C2
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Answer: B. 6

A three-phase inverter has three legs, one for each of the U, V and W phases, each with an upper and a lower switch in series, for a total of six switching devices. Turning the switches on and off in sequence produces three-phase AC.

  • A. Three would give only one switch per phase, unable to switch between positive and negative.
  • B. Correct. 3 phases × 2 switches = 6.
  • C. Two is the count for a single-phase half bridge.
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More Power semiconductors questions

  1. In power circuits and the like, what is the small resistor placed in series in the current path to measure current called?
  2. Why is a switching power supply more efficient than a linear power supply, which operates its transistor linearly?
  3. What is the main advantage of the trench gate structure in power MOSFETs, in which the gate is buried in a groove etched into the silicon?
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  5. What is the main purpose of a snubber circuit in a power device switching circuit?