Multilevel Three-Phase Inverters
Each of the multilevel inverters described in Sec. 8.9 can be expanded to threephase
applications. Figure 8-30 shows a three-phase diode-clamped multilevel
inverter circuit. This circuit can be operated to have a stepped-level output similar
to the six-step converter, or, as is most often the case, it can be operated to
have a pulse-width-modulated output.
8.16 PSPICE SIMULATION OF THREE-PHASE
INVERTERS
Six-Step Three-Phase Inverters
PSpice circuits that will simulate a six-step three-phase inverter are shown in
Fig. 8-31. The first circuit is for a complete switching scheme described in
Fig. 8-28. Voltage-controlled switches with feedback diodes are used for switching.
(The full version of PSpice is required for this circuit.) The second circuit is
for generating the appropriate output voltages for the converter so load currents
can be analyzed. The output nodes of the inverter are nodes A, B, and C. The
parameters shown are those in Example 8-12.
PWM Three-Phase Inverters
The circuit in Fig. 8-32 produces the voltages of the PWM three-phase inverter
without showing the switching details. Dependent sources compare sine waves
to a triangular carrier wave, as in Example 8-8 for the single-phase case.