Forward/Reverse possibilities

Posted on May 17, 2011 at 10:16

Hi,

the maximum you can do to brake quickly is to apply the nominal current 90 decrease in delay (instead of 90 degrees in advance) respect to rotor flux. This will make the bus voltage rise (the kinetic energy is reversed on the bus) and you need to discharge it somehow.

STM32 MC FW Lib can manage a brake resistor to discharge the bus.

There is actually another solution (not supported by the library): try switching on the three low side FET when the motor is running. A current will be generated and it will flow into the motor making it stop very quickly without charging the bus capacitor. you should be anyhow sure that the current (limited by the phase inductance) will be not so high to damage the motor.

Regards,

Billino

Posted on May 17, 2011 at 10:16

Hallo Walterma,

In my application I have to switch very fast between clockwise and counterclockwise, too. The problem is, that it tooks a time till the rotor stop, but I want to stop immediately. So I have to brake the motor fast.

Perhaps someone have an idea what is the best method to stop the motor.

Like I see in the firmware library 2.0, it is not implemented, the brake resistor in the user manual is only to avoid rising of DC Link.

Thanks in advance.

Patrick

Posted on May 17, 2011 at 10:16

Hi,

do you also need a brake resistor to switch very fast between forward and backward rotation? Or can I only apply a DC current? I'm using a STM32.

Thanks!

Posted on May 17, 2011 at 10:16

Yes, it is possible to do it by software.

It is similar to reduce the speed to zero and then to start in the other direction.

To speed down/brake your motor you can apply a DC current in a similar way than during the prepositioning phase. you can bring that way your motor to a stop full.

Starting in the other direction correspond to start with the phases configuration order being reversed.