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TMS320F28069M: Instaspin lab 12b maximum speed operation

Motor_Enthusiast
Intellectual 820 points
Part Number: TMS320F28069M


I am using lab 12b in my own board and want to control a 6 pole motor up to 20krpm.

My switching frequency is 10kHz and with this configuration I can reach up to 9000 rpm. Above this speed, motor becomes out of control.

When I increase switching frequency to 20kHz and keeping USER_NUM_CTRL_TICKS_PER_SPEED_TICK as 10, and USER_NUM_CTRL_TICKS_PER_TRAJ_TICK as 10 I can increase the motor speed up to 18kHz.

Or keeping sw frequency at 10kHz and reducing control ticks to 5 I can reach this speed. According to my observation, speed control frequency / motor electrical frequency has a minimum limit to control the motor properly.

Is it true? If so can I change it? 

  • 0
    TI__Guru** 116090 points

    You'd better use a higher PWM and control frequency for this high-frequency motor. The PWM frequency is at least 18 times the maximum electrical frequency, otherwise, the resolution of the modulation is not enough to achieve the control bandwidth. And please make sure that the resolution of the encoder is also good for high speed.