# What is the best number of PWM signals for Full-Bridge driving? (2 vs 4)

Full-Bridge resonant converter circuit:

Each transistor (Mosfet) has its own driver (ISO5852S).

I assumed that a full bridge could be controlled with two PWMs.

PWM1A, PWM1B, PWM2A, PWM2B.


Each PWM, at its own time step, drives two transistors.

The driver has both inverted and non-inverted inputs, so we can protect the system from through-current in the event of a PWM failure.

I have also seen circuits where 4 separate PWMs are used to control the FULL-Bridge. (PWM1, PWM2, PWM3, PWM4), with A, B outputs for each.

It turns out that in the case of 2 PWMs, only two groups of transistors can be controlled separately. And in the case of 4 PWMs - each transistor separately.

Question:

1. Why are 4 PWMs used instead of 2 to control Full-Bridge?
2. What does the separate control of each transistor give?
• Dead band, phase shift ability, flexibility? Dec 28 '20 at 11:17