Hello everyone, I am trying to design a three phase VVVF as shown in the schematic attached.
I am using a PWM signal as an input to the gate drivers.

I am struggling to understand how to control the output current/voltage by altering the the input PWM signal. What exactly do I change in the PWM signal to control the output (because it contains varying duty cycles to resemble a sine wave, hence I can't easily change each one of them). What I know is that to control the output frequency, we need to alter the input carrier sawtooth frequency that generates the PWM (not sure if thats correct). But I have no idea how to control the ouput voltage.
Please excuse me for this, but I am a beginner in this.

 

Hello everyone, I am trying to design a three phase VVVF as shown in the schematic attached.
I am using a PWM signal as an input to the gate drivers.

Don't they use a higher frequency (carrier wave) sine wave and a comparator circuit to generate the PWM? Used to be a report on the web describing it, but couldn't find it just now.

 

Don't they use a higher frequency (carrier wave) sine wave and a comparator circuit to generate the PWM? Used to be a report on the web describing it, but couldn't find it just now.

I have seen it done where a square wave is fed to an integrator resulting in a triangle wave and the triangle wave into a comparator. You set Vref into the comparator resulting in a PWM signal out.

Ron