Digital current regulator
First Claim
1. In an AC drive having an inverter providing three-phase current and voltage to an induction motor in response to switching signals from a waveform generator to the inverter, the current and voltage having a predetermined frequency and period, a digital current regulator comprising:
- a sensor for sensing two of the three phase currents and providing the same as a first sensed current and a second sensed current;
means for generating a first sensed digital current signal and a second sensed digital current signal functionally related to the first sensed current and the second sensed current in a stationary reference frame;
means for converting the first sensed digital current signal and the second sensed digital current signal into a waveform angle signal and a waveform modulation constant signal in a synchronous reference frame; and
means for generating switching signals from the waveform generator to the inverter in response to the waveform angle signal and the waveform modulation constant signal.
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Accused Products
Abstract
A method and a device for regulating current from an inverter supplying three-phase excitation signals to an induction motor. Two of the three phase currents are converted to digital signals which are sent to a microprocessor. The microprocessor converts the digital signals into a waveform angle signal and a waveform modulation constant signal. The switching signals for the inverter are generated in response to the waveform angle signal and the waveform modulation constant signal.
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Citations
30 Claims
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1. In an AC drive having an inverter providing three-phase current and voltage to an induction motor in response to switching signals from a waveform generator to the inverter, the current and voltage having a predetermined frequency and period, a digital current regulator comprising:
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a sensor for sensing two of the three phase currents and providing the same as a first sensed current and a second sensed current; means for generating a first sensed digital current signal and a second sensed digital current signal functionally related to the first sensed current and the second sensed current in a stationary reference frame; means for converting the first sensed digital current signal and the second sensed digital current signal into a waveform angle signal and a waveform modulation constant signal in a synchronous reference frame; and means for generating switching signals from the waveform generator to the inverter in response to the waveform angle signal and the waveform modulation constant signal. - View Dependent Claims (2, 3, 4, 5)
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6. In an AC drive having an inverter providing three-phase current and voltage to an induction motor in response to switching signals from a waveform generator to the inverter, a method of controlling the current, comprising:
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sensing the voltage from the inverter to the motor and providing the same as a bus voltage; providing a quadrature axis current reference signal and a direct axis current reference signal; generating a quadrature axis current signal and a direct axis current signal; generating a quadrature axis voltage signal in response to the quadrature axis current reference signal, and the quadrature axis current signal; generating a direct axis voltage signal in response to the direct axis current reference signal and the direct axis current signal; generating a voltage magnitude signal and a voltage magnitude angle signal by converting the quadrature axis voltage signal and the direct axis voltage signal from rectangular coordinates to polar coordinates; determining the ratio of the voltage magnitude signal to the bus voltage and providing the same as a waveform modulation constant; providing a reference frame angle signal; summing the reference frame angle signal and the voltage magnitude angle signal and providing the sum as a waveform angle; and generating switching signals from the waveform generator to the inverter in response to the waveform angle and the waveform magnitude constant. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. In an AC drive having an inverter which supplies three-phase voltage and current to an induction motor in response to switching signals from a waveform generator to the inverter, a method for regulating the current, comprising:
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sensing the voltage supplied from the inverter to the induction motor and providing the same as a bus voltage; generating a first digital sensed current signal and a second digital sensed current signal; providing a reference frame angle signal; generating a quadrature axis current signal and a direct axis current signal in response to the first digital sensed current signal, the second digital sensed current signal and the reference frame angle; providing a quadrature axis current reference signal; providing a direct axis current reference signal; generating a quadrature axis voltage signal in response to the quadrature axis current signal and the quadrature axis current reference signal; generating a direct axis voltage signal in response to the direct axis current signal and the direct axis current reference signal; generating a waveform modulation constant signal and a waveform angle signal in response to the quadrature axis voltage signal, the direct axis voltage signal and the reference frame angle signal; and generating switching signals for the inverter in response to the waveform angle signal and the waveform modulation constant signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification