[SOLVED] BLDC motor regenerative breaking

[BoopathiS]

I want to use regenerative breaking concept for breaking 24V, 3A, 30000RPM BLDC motor with hall sensor feedback.

1) Kindly check below breaking procedure is correct or not.
To activate regenrative breaking, switching OFF all higher side MOSFET and applying PWM to lower side MOSFET's in sequential order as per hall sensor feedback. Switching single low side MOSFET for particular hall sensor feedback.
Regenerative current circulates in following path for particular hall sensor feedback(HS3-0, HS2-0, HS1-0),

Motor winding -> Q2 MOSFET -> (Q0)Diode -> Motor winding (During PWM ON period)
Motor winding -> (Q3)Diode -> SMPS -> (Q0)Diode -> Motor winding (During PWM OFF period)

2) How to calculate regenerative energy/current ?

3) If super capacitor is used for storing regenerative energy.It is available only with low voltage. if we are using 24V motor driver, then how to connect it. can you share me any application circuit ?
How to select super capacitor ?

4) Can we use electrolytic capacitor for storing regenerative energy ?

 

[BradtheRad]

I guess the join node of your coils is ground? It would be best if your schematic includes a power source and wiring, as well as current return paths.

 

[KlausST]

Hi,

breaking can be done without hall sensors. Maybe they are useful to determine the RPM and thus control the duty cycle.

Breaking:
* All HIGH SIDE MOSFETS are OFF
* All LOW SIDE MOSFETS get the same PWM.


* the higher the duty cycle the higher the breaking power, the higher the current
* the higher the RPM, the higher the breaking power (squared to RPM?)

so be careful with duty cycle, not to create overcurrent.

Klaus

 

[FvM]

* the higher the duty cycle the higher the breaking power, the higher the current

Not completely true. If you short a synchronous machine (100 % pwm), it will ideally only source reactive power. A small braking effect is achieved due to winding and inverter losses.

Maximal (regenerative) braking is achieved in the same way as maximal drive power, set the "rotating" inverter output voltage to optimal phase and magnitude to get the respective torque generating current, but with inverted sign.

 

[BoopathiS]

Motor breaking is working as per Klaus suggestion in above message. Thanks Klaus, FvM and BradtheRad for valuable input.

 

[Audioguru]

If you want to smash something to pieces then in English you say Breaking.
But to stop something or to slow it down you say Braking.
A car has Brakes, not Breaks.

 

[KlausST]

Hi,

thanks Audioguru for your correction.
As non native English speaker I like to be corrected, else I´ll make the same mistake again and again.

Thanks God it just was the word braking/breaking ;-)


Klaus