Topic: Power Electronics
A DC series motor is driven by a chopper circuit. The supply voltage is 220 V and the duty cycle is 25%. Determine the DC voltage applied to the motor
- A. 165 V
- B. 55 V
- C. 220 V
- D. 110 V
Answer: B. 55 V
Explanation: For a step-down chopper, the average output DC voltage is given by $V_{o(av)} = \alpha V_s$, where $\alpha$ is the duty cycle and $V_s$ is the supply voltage. Given $\alpha = 0.25$ and $V_s = 220\text{ V}$, the voltage applied to the motor is $V_{o(av)} = 0.25 \times 220 = 55\text{ V}$.