Control scheme of EBS on VEC500 MC

[GDare]

Hi everyone,

I am working on a project to implement 2 BLDC motors using the VEC500 MC for a robot. I am currently working on the EBS system and the wiring diagram doesn't provide much detail as to the operation of the EBS. Does the brake pin (blue&white) trigger active high or low? The EBS Auto_Mode speed(rpm) setting triggers this pin (blue&white) or triggers the high brake pin (yellow&white)? I have been experiencing great braking performance from the auto mode when I have been playing with it but now I need to control when the EBS is applied and so I need to know the active state of the pin (Low or High).

Thank you in advance for anyone who can help me to understand the wiring diagram, it is not well documented.

[Bikemad]

Hi andto the forum.

To operate the regenerative braking function the Blue and White wire is simply switched (Grounded) to the Black wire when the brakes are applied. As far as I am aware, the "high brake" option simply allows you to use an existing 12V brake light feed to operate the regen by sending a 12 volt supply to the controller when the brakes are applied. This would typically be used when converting a car or bike etc. which already has a 12V system for the original ancillaries (lights, horn, wipers, demisters, fans, Aircon and radio etc.).

I don't think that the VEC controllers support variable regen, but you could try placing a 10k potentiometer across the two brake wires to see whether the braking force varies, or whether it simply applies full regen at a single position while rotating the potentiometer:

I tried this test on a GM hubmotor controller, but all it did was switch the regen either On or Off. 

I don't suppose the Auto EBS uses either of the brake wire inputs, as I would expect the controller's chip to activate the regen directly according to the measured motor rpm, the programmed rpm value for the Auto EBS, and the user set braking level for the EBS.

Alan
 

[GDare]

Thanks Alan for the feedback.

To operate the regenerative braking function the Blue and White wire is simply switched (Grounded) to the Black wire when the brakes are applied.

Grounding the brake wire would activate EBS and brake the motor? (just as auto mode does?)

I don't think that the VEC controllers support variable regen

What would you expect from some sort of PWM approach to activating the brake pin (modulating the duty cycle)?

[Bikemad]

Grounding the brake wire would activate EBS and brake the motor? (just as auto mode does?)

That is correct, EBS simply uses the electromagnetic dynamic braking force of the motor to slow the vehicle, which can also generate current if the motor rpm is high enough.
Auto mode simply uses the user set rpm level to engage the EBS/regen instead of a brake switch.
The brake switch also cuts the motor power if the throttle is active when the brakes are applied.

What would you expect from some sort of PWM approach to activating the brake pin (modulating the duty cycle)?

I would expect the braking to be very jerky as there seems to be a noticeable delay before the controller actually responds to the switching (both applying and releasing) therefore braking would jerk On and Off but not fast enough to provide progressive and smooth braking.

I haven't tried PWM but I have experimented with manually pulsing the brake switch On and Off with a vector controlled hubmotor, but I was unable to achieve anything near to smooth braking due to the delayed response from the controller.

Alan
 

[GDare]

Is there a setting to disable the braking sound in the VEC controller? When active it beeps?

Does EBS work if the motor is in reverse? If I drive my BLDC 5KW motor in reverse then ground the brake pin, does braking occur the same as in forward? I know that it does not when using the auto mode.

[GDare]

Does EBS work if the motor is in reverse?

The answer is no, I have tested this now and can confirm that the EBS system does not apply a braking force in reverse

[Bikemad]

I have just replied to a similar post regarding the lack of regen braking in reverse, but this is the first time I have heard anyone mention a braking sound from the controller. 

Alan
 

[AJ350925]

Does EBS work if the motor is in reverse?

The answer is no, I have tested this now and can confirm that the EBS system does not apply a braking force in reverse

I can confirm this as well.

I can also say that I did not hear any sound coming from my controller when the EBS was engaged. My controller is a ~2016 NIB VEC500