I have been designing a model of an already existing actuator which is run in FOC with an SVPWM inverter and cascade speed-current control. Losses like eddy current or hysteresis, or switching losses are kept ideal.
The motor which I am using is a PMSM.
As I must rely on the real hardware, I am using the same configuration datas for the controllers. Now I am having trouble with my model, because the results are not really acceptable since the actual speed lies above my target speed whenever I use saturation blocks for the speed controller. The range of them lies within rated torque and 0 and the speed stays above the desired speed.
When I set up the range between rated torque and -rated torque, I am having oscilations around the target speed. The output of the speed controller lies then within the range of my current saturation block.
I keep producing huge current spikes whenever the motor reaches the reference speed. How to avoid them?
BTW: Since there is no feedforward compensation integrated in the digital controller of the hw, I didnt implement one in my actual model. I read that in FOC u just inject the q-term of the FF compensation and dont inject the d-term. Is that right?
Hello
actually it is normal to have ripple when you want to run a motor, but this amount of ripple should be control, because it can even hart your real motor!!
Thanks for your answer. I can imagine that the motor will run unsteady.
I have been thinking to implement a dynamic saturation, which adapts itself whenever the target speed is reached in result to minimize the current spikes.
I added a picture of the current spikes. While accelerating or deaccelerating everything seems fine but the steady state seems to be problematic.
Any other possibilities?
your frequency is changes you must take into consideration your bloc control
Torque ripple in Brushless dc motors is generally undesirable. Torque ripple causes increased acoustic noise and undesirable speed ripple preventing BLDC motor from achieving high performance. Brushless dc motor offer many attractive features like low maintenance, fast response, high efficiency, high power density, good reliability and compact construction.the brushless dc motor is increasingly being used in military, industrial and commercial applications. Its market is rapidly expanding. But these motors still suffer from commutation torque ripple.
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