Driving a BLDC motor with mosfets (highside driving)

Question

I wanted to disconnect power to a bldc motor from a battery (84V,32AH) using mosfets with a low rdson in a highside configuration. I want to do this in a situation where I have more than one battery and if one is discharged I can use the others. I designed a circuit where I used a 555 timer to create a square wave signal then I fed it to a gate drive transformer and then rectified it. In a case where I have multiple batteries, I will need to duplicate the circuit for each battery. I did this so that I can achieve highside driving of the mosfet. I simulated the circuit in ltspice and it worked there. I have shared the circuit below.

Please review it and tell me if it can work practically. Tell me any recommendations, where I can improve and any helpful information about the design and other alternatives.

I used an application note from texas instruments to design the gate drive transformer, link(https://www.ti.com/lit/SLUA618A).

In the circuit, I used the 2n2222 bjt to control the turning on and off of the 555 timer by disconnecting the ground connection of the 555 timer.

Answer 1

The body diodes of the MOSFETs are still there if you turn them off! So the current of an activated battery will flow back into all other deactivated batteries.

16 pF as timing capacitor for NE555 is not ideal, input pin capacitance will add there. 47 kohm and 150 pF are a better combination.

You don't need a full bridge rectifier, remove D3, D4 and D5 and add a jumper in position D4.

EDIT: This is a bipolar switch, just shown with one MOSFET pair. You will add more FETs parallel to meet the 50 A requirement.

^{simulate this circuit – Schematic created using CircuitLab}