Switching Regulator for BLDC Motor

[Hilti]

Hello,

I am designing a BLDC motor driver for an actuator and decided to use OnSemi LV8907 as a pre-driver IC. It has a voltage range from 5.5V to 20V. My input voltage would be 24V nominal but the PCB will be tested on a 36V for 1hour and 48V for 15min. The block diagram of the IC is below.

My questions are;

1) Is it possible to supply this IC with a buck converter and the motor is connected Vbat? Also, can I supply both IC and motor with a buck converter?

2) Could the switching regulator create some EMC problems?

3) Does the regulator have any positive or negative effects for ISO 7637-2 transient voltage pulses?

Or will you advise me to choose a more proper pre-driver with a proper voltage range?

Thank you!

Hilti

 

[BradtheRad]

* Please clarify: Is ground connection at the join of three motor windings? It appears to be star (wye) arrangement.

* High side transistors do not turn on fully unless they receive sufficient bias voltage. In other words, greater than Vbat. Does the IC produce this (for instance via bootstrap circuit)?

* When the motor turns on, expect it to pull down supply voltage as it draws startup surge. It may affect your control IC (since it no doubt requires stable supply voltage). Therefore it's a good idea to have two power converters, one for the control IC, one for the motor.

 

[KlausST]

Hi,

1) I doubt this.
1) Yes. As long as it is stable it does not matter where the voltage comes from.

2) Yes. Any switching node will cause EMI. But properly designed it will be no problem either.

3) ?

..) Yes, choose a suitable driver.

Klaus

 

[Hilti]

Thanks, guys. As far as I understand, choosing a new driver would be appropriate.

2) Yes. Any switching node will cause EMI. But properly designed it will be no problem either.

Dear Klaus,

I am really new at these kinds of stuff and also I am not a elect. engineer. Question will be a little bit off-topic but do you have any recommended source for learning EMC and EMI?

Regards,

Hilti

 

[KlausST]

Hi,

Do an internet search for "EMI PCB layout design" or similar.

And usually every IC manufacturer gives recommendations in the according datasheets and application notes.

Klaus