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InstaSPIN capability

Nigel MacDonald
Prodigy 55 points

We are starting a micro turbine with a 4 pole 5KW starter/generator, with a DC supply of 50V. The maximum starting power is 500W.

We dwell at around 5Krpm for a few seconds, with no mechanical load, to ignite the fuel and then run  up to 100K RPM where the turbine takes over. At the full speed of 200Krpm we generate about 90 Volts rectified DC. We currently use Hall sensors, but would like to go sensorless. We need to measure rpm up to full speed and voltage.

  • TI__Guru** 119680 points

    what is the unloaded current draw of the motor? If 100A loaded I'm thinking is probably <20A unloaded.

    you should be able to test this initially with DRV8301-69M-KIT.

    I am thinking though that you may have to change the phase voltage filter cut-off frequency in both HW and SW. The existing pole is at 335 Hz. You will want to change this to your max frequency / 4, so 833 Hz for a 4 pole 100K RPM motor.

    and I'd set up my ticks as

    #define USER_PWM_FREQ_kHz                (30.0)
    #define USER_NUM_PWM_TICKS_PER_ISR_TICK        (1)
    #define USER_NUM_ISR_TICKS_PER_CTRL_TICK       (1)  
    #define USER_NUM_CTRL_TICKS_PER_CURRENT_TICK   (1)   
    #define USER_NUM_CTRL_TICKS_PER_EST_TICK       (3)  // FAST running at 10 KHz
    #define USER_NUM_CTRL_TICKS_PER_SPEED_TICK  (30)  
    #define USER_NUM_CTRL_TICKS_PER_TRAJ_TICK   (30)