hI, i started a 220v 3ph inverter project with arduino mega as a controller and after a some period of learning ans destroying i am stuck in the step of triggering the gate of the igbt i selected for this work.
Iam using a ir2110 to drive an stgy40nc60vd igbt, the thing is i need an explanation of how the bootstrap circuits works, does anybody could help?
Yes, it relies on the PWM waveform. This means the emitter of the high-side IGBT is pulled to ground
regularly by the low-side IGBT.
This means the diode in the bootstrap circuit charges the flying capacitor up, so it can power the high
side gate driver for a short period (until the next time the low-side IGBT is on).
The key rule is that the high side cannot be held on for more than a short time (which for PWM
means you are limited to say 95% maximum duty cycle).
Its absolutely vital the diode is fast enough, and can take the peak inverse voltage.
The flying bootstrap capacitor must be at least 10 times the effective gate capacitance.
Often a small value resistor is included in series with the diode to reduce peak current,
10 ohms or so. Note the datasheet shows a SiC 10KF6 high voltage diode in their suggested circuit.