Control technique for limiting the current of an induction machine drive system
First Claim
1. A method of deriving phase voltage control signals suitable for use in controlling current flow to an induction motor, said method comprising the steps of:
- subtracting a stator phase current value from a commanded current value to obtain an error term;
converting said error term into a commanded voltage value in synchronous reference frame;
transforming said commanded voltage value into a commanded voltage vector in stationary reference frame; and
converting said commanded voltage vector into the phase voltage control signals via a pulse width modulation control;
wherein said stator phase current value comprises a value derived from a stator phase current Park vector stationary reference frame.
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Abstract
A method and apparatus for deriving phase voltage control signals for use in controlling current flow to an induction motor. The method may comprise obtaining an error term; converting the error term into a commanded voltage value; transforming the commanded voltage value into a commanded voltage vector; and converting the commanded voltage vector into the phase voltage control signals via pulse width modulation control. The apparatus may comprise a Park vector converter for converting a first stator phase measurement and a second stator phase measurement into a stator phase current vector; a scalar operator for obtaining a stator phase current value; a summer for obtaining an error term; an error converter for converting the error term into a commanded voltage value; a voltage transformer for transforming the commanded voltage value into a commanded voltage vector, and pulse width modulation control for converting the commanded voltage vector into the phase voltage control signals.
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Citations
35 Claims
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1. A method of deriving phase voltage control signals suitable for use in controlling current flow to an induction motor, said method comprising the steps of:
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subtracting a stator phase current value from a commanded current value to obtain an error term; converting said error term into a commanded voltage value in synchronous reference frame; transforming said commanded voltage value into a commanded voltage vector in stationary reference frame; and converting said commanded voltage vector into the phase voltage control signals via a pulse width modulation control; wherein said stator phase current value comprises a value derived from a stator phase current Park vector stationary reference frame. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of deriving phase voltage control signals suitable for use in controlling current flow to an induction motor, said method comprising the steps of:
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obtaining a first stator current measurement for a first phase of the induction motor; obtaining a second stator current measurement for a second phase of the induction motor; transforming said first and second stator current measurements into a stator phase current value via a Park vector transformation; subtracting said stator phase current Park vector value from a commanded current Park vector magnitude value to obtain an error term; operating on said error term via a regulator to obtain a terminal signal; integrating said terminal signal to obtain a commanded voltage value in synchronous reference frame; transforming said commanded voltage value into a commanded voltage vector in stationary reference frame; and converting said commanded voltage vector into the phase voltage control signals via a pulse width modulation control. - View Dependent Claims (18, 19, 20)
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21. A controller suitable for providing phase voltage control signals to an induction motor, said controller comprising:
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a Park vector converter for converting a first stator measurement of a first phase of the induction motor and a second stator measurement of a second phase of the induction motor into a stator phase current Park vector in stationary reference frame; a scalar operator for obtaining the magnitude of said stator phase current Park vector to yield a stator phase current Park vector magnitude value; a summer for subtracting said stator phase Park vector current value from a commanded current Park vector value to obtain an error term; an error converter for converting said error term into a commanded voltage Park vector magnitude value in synchronous reference frame; a voltage transformer for transforming said commanded voltage Park vector magnitude value into a commanded voltage vector in stationary reference frame; and a pulse width modulation control for converting said commanded voltage vector into the phase voltage control signals. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. An induction machine drive system comprising:
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an induction motor having a first current sensor for measuring a first stator phase current, said induction motor further having a second current sensor for measuring a second stator phase current; an inverter for transmitting power from a DC link to said induction motor; a controller for receiving a first stator current measurement from said first current sensor, said controller further for receiving a second stator current measurement from said second current sensor, said controller including; a Park vector converter for converting said first stator current measurement and said second stator current measurement into a stator phase current Park vector; a scalar operator for obtaining the magnitude of said stator phase current Park vector to yield a stator phase current value; a voltage vector generator for producing a commanded voltage vector as a function of said stator phase current value and a commanded current value; a space vector modulation control for producing a plurality of phase voltage control signals from said commanded voltage vector; and a gate drive for converting said plurality of phase voltage control signals into a control signal for said inverter. - View Dependent Claims (31, 32, 33, 34, 35)
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Specification