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Control of motor drives with output sinewave filter capacitor current compensation using sinewave filter transfer function

  • US 9,800,190 B2
  • Filed: 02/03/2016
  • Issued: 10/24/2017
  • Est. Priority Date: 02/03/2016
  • Status: Active Grant
First Claim
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1. A power conversion system, comprising:

  • an inverter comprising a DC input, an AC output, and a plurality of switching devices coupled between the DC input and the AC output and operative according to inverter switching control signals to convert DC electrical power received at the DC input to provide AC electrical output power at the AC output to drive a motor load through an intervening output filter; and

    a controller configured to;

    compute a speed error value according to a speed reference value and a speed feedback value using a summing component;

    compute a torque reference value according to the speed error value using a first proportional-integral (PI) control component;

    compute a motor current reference value according to the torque reference value using a lookup table or a parametric equation;

    compensate the motor current reference value according to capacitor currents of the output filter by computing an inverter output current reference value according to the motor current reference value and an inverter operating frequency using a first transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load; and

    provide the inverter switching control signals to control the inverter according to the inverter output current reference value;

    wherein the controller is operative to control the inverter according to the inverter output current reference value by;

    computing an inverter output current value according to the inverter output current reference value and an inverter output current value, andproviding the inverter switching control signals to control the inverter according to the inverter output current value; and

    wherein the controller is operative to estimate the speed feedback value by;

    computing a motor current value according to the inverter output current value and the inverter operating frequency using the first transfer function,computing a motor torque value according to the motor current value, andcomputing the speed feedback value according to the motor torque value.

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