System for calibrating an electrical control system
First Claim
1. A method of calibrating a current sensing instant to latch a current value from a set of current signals comprising:
- providing a current command including a magnitude at a Gamma angle to control a motor when the motor is operating in a motoring mode at a shaft speed;
providing a matching current command including a same magnitude at a same Gamma angle to control the motor when the motor is operating in a braking mode at a same shaft speed;
monitoring, when the motor is controlled by the current command and operating in the motoring mode, a first actual averaging rms current magnitude of three phase currents of the motor;
monitoring, when the motor is controlled by the matching current command and operating in the braking mode, a second actual averaging rms current magnitude of the three phase currents of the motor;
adjusting a current sensing instant until an observed first actual averaging rms current magnitude in the motoring mode equals an observed second actual averaging rms current magnitude in the braking mode.
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Accused Products
Abstract
A method calibrates a current sensing instant to latch a current value from a set of current signals. A current command including a magnitude at a Gamma angle is provided to control a motor when the motor is operating in a motoring mode at a shaft speed. A matching current command including a same magnitude at a same Gamma angle is provided to control the motor when the motor is operating in a braking mode at a same shaft speed. A first actual averaging rms current magnitude of three phase currents of the motor is monitored when the motor is controlled by the current command and operating in the motoring mode. A second actual averaging rms current magnitude of the three phase currents of the motor is monitored when the motor is controlled by the matching current command and operating in the braking mode. A current sensing instant is adjusted until an observed first actual averaging rms current magnitude in the motoring mode equals an observed second actual averaging rms current magnitude in the braking mode.
44 Citations
23 Claims
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1. A method of calibrating a current sensing instant to latch a current value from a set of current signals comprising:
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providing a current command including a magnitude at a Gamma angle to control a motor when the motor is operating in a motoring mode at a shaft speed; providing a matching current command including a same magnitude at a same Gamma angle to control the motor when the motor is operating in a braking mode at a same shaft speed; monitoring, when the motor is controlled by the current command and operating in the motoring mode, a first actual averaging rms current magnitude of three phase currents of the motor; monitoring, when the motor is controlled by the matching current command and operating in the braking mode, a second actual averaging rms current magnitude of the three phase currents of the motor; adjusting a current sensing instant until an observed first actual averaging rms current magnitude in the motoring mode equals an observed second actual averaging rms current magnitude in the braking mode. - View Dependent Claims (2, 3, 4, 5)
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6. A system for processing a sensed current signal from a motor, the system comprising:
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a digital signal processor; a field programmable gate array in communication with the digital signal processor; the digital signal processor being configured to generate a digital pulse indicating a current sensing instant at which to latch a current value from a sensed current signal from a motor, a rising or falling edge of the digital pulse being configured to correspond to an averaging point of the sensed current signal; the field programmable gate array being configured to receive a continuously sensed three phase current signal from a motor and the digital pulse from the digital signal processor, the field programmable gate array configured to latch a set of three phase current values from the continuously sensed current signal at the current sensing instant indicated by the rising or falling edge of the digital pulse, and transmit the latched three phase current values to the digital signal processor. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method of calibrating inverter current transducers for a machine controller, the method comprising:
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commanding a known DC current through a machine winding; receiving a feedback current from the machine controller; comparing the feedback current to the known DC current; calculating a scaling ratio based on the comparison; repeating the steps of commanding, receiving, comparing, and calculating a plurality of times, each time using a different known DC current magnitude; generating a lookup table comprising the calculated scaling ratios for the known DC current magnitudes; wherein the known DC current is commanded through the machine winding in a first direction; commanding the known DC current through the machine winding in a second direction opposite the first direction; receiving a second feedback current from the machine controller; comparing the second feedback current to the known DC current; and calculating a second scaling ratio based on the comparison. - View Dependent Claims (13, 14)
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15. A method of calibrating inverter current transducers for a machine controller, the method comprising:
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commanding a known DC current through a machine winding; receiving a feedback current from the machine controller; comparing the feedback current to the known DC current; calculating a scaling ratio based on the comparison; repeating the steps of commanding, receiving, comparing, and calculating a plurality of times, each time using a different known DC current magnitude; generating a lookup table comprising the calculated scaling ratios for the known DC current magnitudes; verifying the scaling ratio using AC current; and wherein verifying the scaling ratio comprises commanding a specific current magnitude at a moderate Gamma angle through machine, receiving an actual average three phase current from the machine, and comparing the actual average three phase current to the commanded specific current magnitude. - View Dependent Claims (16)
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17. A method performed by a processor of calculating a time delay associated with receiving and processing a current signal, the method comprising:
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measuring a hardware circuit phase delay by the processor; measuring a current samples processing or filtering delay by the processor; estimating a current reading delay by the processor; measuring a power switches deadtime delay by the processor; and adjusting by the processor a current sensing instant used to latch a current value from a continuously sensed current signal buffer, the adjustment based on a total delay from the measured hardware phase delay, the measured current samples processing delay, the estimated current reading delay, and the measured power switches deadtime delay. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification