Regarding Spikes in Phases in BLDC Controller

[Karthik DM]

Hello All, 

I'm developing 48Volt 700Watt BLDC Motor Controller Using STM32 Controller. 

I didn't use STM Motor Control Workbench Tool for this Project. I developed my own library and source code for this project. 

When motor is running initial spikes is coming and at the center of the graph another spikes also coming.

Can anyone please tell me why this problem is happening in controller.

Here I'm attaching the Phase U(Yellow) and Phase V (Blue) waveform.

Please check and let me know.

Thanks & Regards

Karthik DM

E-Mail : karthikdm1997@gmail.com

[Enrico Poli · Accepted solution]

Hi @Karthik DM​,

The spikes at the beginning of the high-impedance step are due to demagnetization of the motor phase.

In fact when you turn off both the HS and LS MOSFETs the current that was flowing into the winding is discharged using the body diodes. According to the direction of the current the HS (half bridge sinks the current) or LS (half bridge sources the current) diode is turned on.

The spikes in the middle, in my opinion, are generated by some configuration change inside the timer you are using for the PWM causing glitches on the outputs.

Please check if between two steps of the sequence you change the configuration of the timer and how it is managed by the peripheral.

[Karthik DM]

Hello Enrico Poli, Thanks for your valuable suggestions. As suggested by you the middle spikes are due to change in timer configuration. I mistakenly did some wrong configuration. Now its working fine and efficiently.

Thanks You.