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US 9,287,812 B2Granted
Method and apparatus for stability control of open loop motor drive operation
AssigneeRockwell Automation Technologies, Inc.
InventorsThomas Nondahl, Jingbo Liu, Peter Schmidt, Semyon Royak, Timothy M. Rowan
Life of this patent
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Abstract
Motor drives and control methods are presented for sensorless motor speed control in which inverter output currents are sampled from the inverter output and a frequency modulation value is determined based on the current feedback. A speed or frequency setpoint is adjusted at least partially according to the frequency modulation value to provide an adjusted frequency or speed setpoint value that is then used in controlling the inverter to provide stability control to mitigate hunting or motor stoppage.
Claims20
A method for sensorless motor speed control in a motor drive, the method comprising:
- sampling at least one multiphase AC output current feedback signal or value from an output of an inverter of the motor drive;
- computing a frequency modulation value in a stationary reference frame based on the at least one multiphase AC output current feedback signal or value;
- adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value;
- and
- controlling the inverter according to the adjusted frequency or speed setpoint value.
2 more elements
A method for sensorless motor speed control in a motor drive, the method comprising:
- sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
- computing a frequency modulation value based on the at least one AC output current feedback signal or value;
- adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value;
- and
- controlling the inverter according to the adjusted frequency or speed setpoint value:
- wherein adjusting the frequency or speed setpoint value comprises:
- rate limiting the frequency or speed setpoint value to provide a rate limited frequency or speed setpoint value;
- and
- subtracting the frequency modulation value from the rate limited frequency or speed setpoint value to provide the adjusted frequency or speed setpoint value.
6 more elements
A method for sensorless motor speed control in a motor drive, the method comprising:
- sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
- computing a frequency modulation value based on the at least one AC output current feedback signal or value;
- adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value;
- and
- controlling the inverter according to the adjusted frequency or speed setpoint value:
- wherein adjusting the frequency or speed setpoint value comprises subtracting the frequency modulation value from the frequency or speed setpoint value to provide the adjusted frequency or speed setpoint value.
3 more elements
A method for sensorless motor speed control in a motor drive, the method comprising:
- sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
- computing a frequency modulation value based on the at least one AC output current feedback signal or value;
- adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value;
- and
- controlling the inverter according to the adjusted frequency or speed setpoint value:
- wherein computing the frequency modulation value comprises:
- computing an estimated per unit output current signal or value based on the at least one AC output current feedback signal or value;
- and
- computing the frequency modulation value based at least partially on the estimated per unit output current signal or value.
6 more elements
A method for sensorless motor speed control in a motor drive, the method comprising:
- sampling at least one AC output current feedback signal or value from an output of an inverter of the motor drive;
- computing a frequency modulation value based on the at least one AC output current feedback signal or value;
- adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value;
- and
- controlling the inverter according to the adjusted frequency or speed setpoint value:
- wherein computing the frequency modulation value comprises:
- converting a plurality of AC output current feedback signals or values to a synchronous reference frame to compute an estimated output current signal or value in the synchronous reference frame, and
- computing the frequency modulation value based at least partially on the estimated output current signal or value in the synchronous reference frame.
5 more elements
A non-transitory computer readable medium with computer executable instructions for sensorless motor speed control in a motor drive, the computer readable medium comprising computer executable instructions for:
- sampling at least one multiphase AC output current feedback signal or value from an output of an inverter of the motor drive;
- computing a frequency modulation value in a stationary reference frame based on at least one of the multiphase AC output current feedback signal or value and at least one voltage command or feedback signal or value;
- adjusting a frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value;
- and
- controlling the inverter according to the adjusted frequency or speed setpoint value.
2 more elements
A motor drive, comprising:
- an inverter including a plurality of switching devices operable according to switching control signals to provide AC output power to drive a motor load;
- and
- a sensorless motor speed controller providing the switching control signals to the inverter to regulate the AC output power at least partially according to a frequency or speed setpoint value, the sensorless motor speed controller comprising:
- a signal generator component operative to compute a frequency modulation value in a stationary reference frame based on at least one multiphase AC output current feedback signal or value representing at least one AC output current of the inverter,
- an adjustment component operative to adjust the frequency or speed setpoint value based at least partially on the frequency modulation value to provide an adjusted frequency or speed setpoint value, and
- a command generator component operative to provide the switching control signals to the inverter at least partially according to the adjusted frequency or speed setpoint value.
3 more elements
Dependencies are inferred from the claim text.