BLDC motor driver circuit

[gauravkothari23]

Hi all,
I want to drive 24V 2A BLDC motor using Nuvoton MS51FB9AE 8051 controller.
But i am bit confused with the circuit diagram. After going through some of the articles provided online some circuit shows N channel mosfet on High Side and same N Channel mosfet on Low side also. and some shows P channel mosfet on High side and N Channel mosfet on Low Side.
Can anyone please suggest me what type of mosfets can be used. and if both type can be used what would be the driving difference between this two circuits.

 

[D.A.(Tony)Stewart]

In practical terms a low RdsOn Nch can be made slightly lower than Pch for the same die size and cost so is preferred. A boost cap and diode relies on the low side PWM and top side for direction control.

Complementary P/N also works.

The critical parameters should be the RdsOn*C and load regulation effects. They tend to be tradeoffs but some are better than others and varies widely with material SiO2, GaN, S

 

[gauravkothari23]

In practical terms a low RdsOn Nch can be made slightly lower than Pch for the same die size and cost so is preferred. A boost cap and diode relies on the low side PWM and top side for direction control.

Complementary P/N also works.

The critical parameters should be the RdsOn*C and load regulation effects. They tend to be tradeoffs but some are better than others and varies widely with material SiO2, GaN, S

Will try using Complementary P/N type FDS4559 Mosfet as per your suggestions
for gate driving can use NPN transistors for both N channel and P channel Mosfet. Will use P Channel for PWM speed control and N channel for Direction Control.

 

[gavinray]

Hi all,
I want to drive 24V 2A BLDC motor using Nuvoton MS51FB9AE 8051 controller.
But i am bit confused with the circuit diagram. After going through some of the articles provided online some circuit shows N channel mosfet on High Side and same N Channel mosfet on Low side also. and some shows P channel mosfet on High side and N Channel mosfet on Low Side.
Can anyone please suggest me what type of mosfets can be used. and if both type can be used what would be the driving difference between this two circuits.

For driving a 24V 2A BLDC motor with a Nuvoton MS51FB9AE 8051 controller, you can use both types of MOSFET configurations (N-channel on both high and low side, or P-channel on the high side and N-channel on the low side), but there are key differences in how they are driven:

1. N-Channel MOSFETs on High and Low Side:
   • Driving complexity: This requires a high-side driver to properly switch the N-channel MOSFET on the high side, because the gate voltage needs to be higher than the source voltage to turn it on.
   • Advantages: N-channel MOSFETs generally have better performance (lower Rds(on), higher current capability) than P-channel MOSFETs.
2. P-Channel MOSFET on High Side, N-Channel on Low Side:
   • Simpler driving: P-channel MOSFETs are easier to drive on the high side, as they turn on when the gate is pulled low (relative to the source). N-channel MOSFETs can be used on the low side directly with the gate driven by the controller.
   • Disadvantages: P-channel MOSFETs usually have higher Rds(on) and worse performance than N-channel MOSFETs.

Driving Difference:​

• N-channel on both sides needs additional circuitry like bootstrapping or dedicated high-side drivers.
• P-channel on high side simplifies the gate drive but sacrifices performance compared to N-channel MOSFETs.

If you want efficiency and better control, go with N-channel MOSFETs on both sides, using appropriate high-side driver circuits.

 

[naania]

For driving a 24V 2A BLDC motor with a Nuvoton MS51FB9AE 8051 controller, you can use both types of MOSFET configurations (N-channel on both high and low side, or P-channel on the high side and N-channel on the low side), but there are key differences in how they are driven:

1. N-Channel MOSFETs on High and Low Side:
   • Driving complexity: This requires a high-side driver to properly switch the N-channel MOSFET on the high side, because the gate voltage needs to be higher than the source voltage to turn it on.
   • Advantages: N-channel MOSFETs generally have better performance (lower Rds(on), higher current capability) than P-channel MOSFETs.
2. P-Channel MOSFET on High Side, N-Channel on Low Side:
   • Simpler driving: P-channel MOSFETs are easier to drive on the high side, as they turn on when the gate is pulled low (relative to the source). N-channel MOSFETs can be used on the low side directly with the gate driven by the controller.
   • Disadvantages: P-channel MOSFETs usually have higher Rds(on) and worse performance than N-channel MOSFETs.

Driving Difference:​

• N-channel on both sides needs additional circuitry like bootstrapping or dedicated high-side drivers.
• P-channel on high side simplifies the gate drive but sacrifices performance compared to N-channel MOSFETs.

If you want efficiency and better control, go with N-channel MOSFETs on both sides, using appropriate high-side driver circuits.
[Spam deleted]

really useful for me, tks a lot

 

[bogdandavyd]

If the MOSFETs are heating up too much, it could be due to incorrect gate drive signals or dead time issues. A weak gate driver might not fully turn on the MOSFETs, causing higher resistance and heat.

Also, check the PWM frequency. Too high can lead to excessive switching losses. If you're working on a bldc fan motor, make sure the hall sensors or sensorless controller are properly tuned to avoid unnecessary stress on the MOSFETs.