For a hobby project I would like to switch between two power supplys. The load are two motors which can also be switched on and off separatly. The two motors are BLDC controllers in reality. I am only in developing phase so no test arrangement was done.
- U4-7 are highside MOSFET drivers with an integrated charge pump to achieve voltages above VCC.
- R7, R8, R15, R16 are pull-down resistors to avoid floating potentials on the driver input and R1, R2, R9, R10 have the same function but at the output of the drivers.
- Q1-4 are my n-channel power MOFETS (V_GS_max = +/-16V)
- R3, R6, R11, R14 are restricting the maximum gate current
- and R4, R5, R12, R13 I think are necessary to ensure that V_GS is never above 16V despite the source potential is floating (e.g. if Q1 is on and Q3 is off)
- Maximum power-supply voltage: ~25V
- Maximum current: ~50A through Q1/Q2 and ~25A through Q3/Q4
- Q1 and Q2 can not be on at the same time (software-wise)
- Q3/Q4 are PWM driven the first second after startup (to reduce the inrush current of the BLDC capacitors)
So my questions are:
- are there any considerations for stable operation?
- are there any maximum ratings which could be exceeded (especially V_GS or crossflows)?
I would appreciate your advices!
The problem with transverse currents if one battery has a lower voltage than the other is in a new thread: MOSFET-switching between two power supplys: how to avoid transverse current?