1
\$\begingroup\$

I have been developing software for field oriented control of the three phase induction motor. I have been facing a problem how to incorporate changing of rotation direction into the control software. The requirement is to achieve a state where the motor is able to operate in all four quadrants of the torque-speed plane i.e. the machine shall work in motoring (braking) mode for both directions of rotation.

The rotation direction of the three phase induction motor is in my opinion given by the phase sequence of the stator three phase voltages which are basically produced by the three phase voltage source inverter in my situation. The problem which I have is how to incorporate change in the phase sequence of the stator three phase voltages in case the output of the control structure (the controllers of the torque and flux components of the stator current) is the desired space vector of the stator voltage. Can anybody help how to do that? Thanks in advance for any ideas.

\$\endgroup\$
4
\$\begingroup\$

The FOC already does all of this. If the motor's actual velocity is higher than it's velocity setpoint, then you will have a generator mode. You can even control the torque with Iq setpoint. For example:

if n>0 // positive direction
  Iq= -Iq_set;  // negative torque (braking)
elseif n<0 // negative direction
  Iq = Iq_set; //positive torque (braking)

The above pseudo algorithm however is yet implemented by simply giving the velecotiy setpoint = 0. If the external load will try to spin the motor, the FOC will brake it.

This is a block scheme of FOC with velocity control. In case you want to have a torque mode only, then you disable the speed controller and you set the torque directly by changing the Iq setpoint. This block is for PMSM, for the induction motor would differ in Id setpoint calulation and it would have an extra rotor flux estimator.

enter image description here

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.