I will teach you PWM to my best........
Let me try this........
1. PWM - Pulse Width Modulation
2. Its purely control phenomenon and helps you generating triggering signals
3. Triggering signals..? What is this....
Consider combination of 4 MOSFETS (Power Electronic Switches, which have switching frequecny of 100K Hz i.e. a MOSFET can turn off and on 100000 times in a sec., certainly un imaginable ) such that it forms an INVERTER configuration.
As we know, o/p of Inverter to be a Pure Sine wave (certain Voltage Vo = 230 V rms and Frequecny Fo = 50 Hz), But how to produce it.
Inverter is fed with DC input supply (mandatory) , and a control technique.
There are numorous control techniques available (PWM, Hys, SMC, PID, etc )
PWM is very basic and very popular technique , which can easily understood and fabricated on board unlike others.
In our case, 600 V rated MOSFET is required ....Even a MOSFET of 10KV and 3000A rating needs only 5 V or 10 V supply at its gate terminal to turn it on i.e. beauty of Power Electronics (Controlling bulk power with 10V)
4. In PWM , two signals will be compared of which one must be Triangular and other may be choice.
To choose second,
If output of Inverter is to be Sine wave, then choose Sine hence called Sine PWM
If output of Inverter is to be Square , then choose Square wave , called Square PWM
5. Both signals, triangle and sine signal (known as control signal), will be of amplitude of maximum 1V only
6. Frequency of output Sine signal will be same as control signal.
Reply me if any clarification needed