Electrotechnical Systems

217Electric Machine and Electric Drive Simulation

PWM uses single-polar modulation as discussed in Chapter 4, Figure 4.41. The

modulation relations are as follows:

if V

ref

≥ 0 and V

ref

≥ V

cp

, conduct T1 and T4, that is, V

k

= E

if V

ref

≥ 0 and V

ref

< V

cp

, conduct T2 and T4, that is, V

k

= 0

if V

ref

< 0 and V

ref

> V

cp

, conduct T2 and T4, that is, V

k

= 0

if V

ref

< 0 and V

ref

≤ V

cp

, conduct T2 and T3, that is, V

k

= −E

The triangular carrier waves of each sell in the same phase are shifted by about 120°.

The voltage sensor and the scope are set in the phase A subsystem.

Two modes of IM control are provided that are selected with the tumbler switchS.

In its ...