Question

A small electric vehicle is powered by a 96 V battery and uses a series wound motor. It has a step down chopper for forward drive and a step-up chopper for regenerative braking. The total armature voltage constant is 10 mV/A rad/s. Descending a hill in regeneration mode, the motor speed is 1000 rev/min and the armature current has a constant average value of 80 A. The value of the duty cycle required is _____.

• A. 0.17

Answer 1

The correct option is A 0.17
$E=K\omega I_a$
$=10\times {10}^{-3}\times \frac{2\pi \times 1000}{60}\times 80=84V$

$V_0=E-I_{a}R$

= 84 - 40 × 0.1 = 80 V

$V_0=V_b(1-D)$

$(1-D)=\frac{V_0}{V_b}=\frac{80}{96}$

D = 0.17