Helping in the selection MOSFET (For BLDC Motor controller)

[pes68]

I wanna choose a MOSFET for brushless motor controller ( 36 volt , 15 Amps)
Which is more important in the selection ? (Power MOSFET for BLDC motor controller , about 20KHz PWM frequency)
Low Rds(on)
Low Qtotal (gate charge value)
Low Resistive Switching Times (tr , tf , ton , toff)
Low trr (reverse recovery time )
or ... ?

please guide me

 

[c_mitra]

Is it a three phase motor? You will need at least 3 mosfets and if you want sine wave driver, you will need six (half bridge for each phase). Please tell more about the motor.

20KHz is PWM frequency but do you also wish to have variable sine frequency of the output? What will be the range you are planning? (say 20-200 or 50-2000; some range will be needed).

There are mosfet drivers for three phase that can be used.

The parameters that you need to focus will be: (in this order)

1. Voltage; 2. Current; 3. gate drive (logic level or standard); 4. Rds(on)

As this is a rather low power (36V, 15A)- and you are not using a real high frequency- 20KHz, other parameters are important but not critical.

 

[pes68]

Is it a three phase motor? You will need at least 3 mosfets and if you want sine wave driver, you will need six (half bridge for each phase). Please tell more about the motor.

20KHz is PWM frequency but do you also wish to have variable sine frequency of the output? What will be the range you are planning? (say 20-200 or 50-2000; some range will be needed).

There are mosfet drivers for three phase that can be used.

The parameters that you need to focus will be: (in this order)

1. Voltage; 2. Current; 3. gate drive (logic level or standard); 4. Rds(on)

As this is a rather low power (36V, 15A)- and you are not using a real high frequency- 20KHz, other parameters are important but not critical.

thank you.
it is a three phase e-bike hub BLDC motor ( 36 V , 500W). i need 6 N-channel MOSFET (Half bridge for each phase).
I think MOSFETs with voltage of 60 V and current of 80 A is appropriate. Do you think enough ?
High efficiency is important for me, so i focus on Low Rds Or Low trr Or another parameter ?

 

[c_mitra]

I presume you are planning to run from a 24-36V source, with three phases synthesised in software. For speed control, it is best to use the basic ideas of the variable frequency drive.

60V may be somewhat borderline; at switch off, back emf of 36V and forward voltage of 36V will act in series; consider using at least 100V.

80A current is not needed as your motor is 500W power. You can consider 50A max (40A may be sufficient also: select based on the other criteria).

All the MOSFETs need to be mounted on heatsinks but for the cause of efficiency select the lowest Rds(on) compatible with your requirements.

There are three phase drivers that can simplify your design but use decoupling capacitors liberally where ever needed.