VOLTAGE ORIENTED CONTROL – SIMULATION
3.3 PWM Simulation
A description of the sinusoidal PWM implemented here is available in section “2.4 Pulse Width Modulation”.
3.3.1 Simulink implementation of PWM
Â PWM block using switch
The amplitude of triangular wave should be Vdc/2. But Vdc is not constant in our case. We should first normalized the reference value by Vdc/2 and compare this value with a triangular wave with an amplitude of 1. The following figure show the Simulink block diagram.
Figure 3.3 : Simulink PWM block
Â PWM block without switch
We can also use a PWM block without switching to create the switching pattern. The reference voltage is normalized by Vdc/2 to obtain a signal within a range [ 1 ; +1], then divide by 2 and translate to get signal in the range [0 ; +1] like the switching function Sabc. This simple model can be useful in Simulink to reduce the simulation time if needed. In a complete simulation with controller, the behavior of the system is similar using Figure 3.3 or Figure 3.4.
Figure 3.4 : Simulink PWM block without triangular wave