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Methods, systems and apparatus for computing a voltage advance used in controlling operation of an electric machine

  • US 8,583,265 B1
  • Filed: 05/22/2012
  • Issued: 11/12/2013
  • Est. Priority Date: 05/22/2012
  • Status: Active Grant
First Claim
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1. A method, comprising:

  • iteratively executing a slow-rate task processing loop that executes at a relatively slow-rate during a first task processing period (TTASK2);

    iteratively executing an intermediate-rate task processing loop that executes at an intermediate-rate during a second task processing period (TTASK1), wherein the step of iteratively executing the intermediate-rate task processing loop, comprises;

    computing, at the intermediate-rate (TTASK1), a new instantaneous switching frequency (fSW

    new); and

    computing tri-state values for a PWM voltage advance delay time, wherein the tri-state values for the PWM voltage advance delay time comprise;

    an initial steady-state value for the PWM voltage advance delay time (tPWM

    Adv

    inital

    ss);

    an intermediate value for the PWM voltage advance delay time (tPWM

    Adv

    intermediate); and

    a final steady-state value for the PWM voltage advance delay time (tPWM

    Adv

    final

    ss);

    iteratively executing a fast-rate task processing loop that executes at a relatively fast-rate during a third task processing period (TTask0), wherein iteratively executing the fast-rate task processing loop comprises;

    computing tri-state values for a PWM voltage advance angle (Δ

    θ

    ) that are used during a transition state when a current actual switching frequency (fSW) changes to the new instantaneous switching frequency (fSW

    new), wherein the tri-state values for the PWM voltage advance angle (Δ

    θ

    ) are computed based on;

    a product of the initial steady-state value for the PWM voltage advance delay time (tPWM

    Adv

    inital

    ss) and an angular rotor velocity (ω

    r);

    a product of the intermediate value for the PWM voltage advance delay time (tPWM

    Adv

    intermediate) delay time and the angular rotor velocity (ω

    r); and

    a product of the final steady-state value for the PWM voltage advance delay time (tPWM

    Adv

    final

    ss) delay time and the angular rotor velocity (ω

    r).

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