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US 7,135,833 B2Granted
Motor control for flux-reduced braking
AssigneeRockwell Automation Technologies, Inc.
InventorsRobert J. DeLange, Timothy M. Rowan
Life of this patent
Estimating the term…
Abstract
A method and apparatus for braking an AC motor in the higher portion of its speed range includes substantially reducing flux before applying reverse torque commands to brake the motor. A DC link bus regulator is employed to prevent increases in bus voltage and frequency.
Claims23
A method of flux-reduced braking of an AC motor, comprising:
- reducing commanded voltage while holding output frequency at a last running value to reduce flux in the motor;
- upon reaching a flux-reduced level, reducing the output frequency by at least 40% and then sensing dc bus voltage to provide a feedback signal that regulates the frequency as a function of dc bus voltage to provide control of frequency down to about 3 Hz.;
- and
- upon reaching the flux-reduced level, providing a motor current regulation loop to control the motor and providing with current commands to the motor current regulation loop that provide braking torque to the motor.
1 more element
A controller for flux-reduced braking of an AC motor, comprising:
- a microelectronic CPU for executing a stored control program to provide a dc bus voltage regulator that receives a dc reference voltage and a dc feedback voltage and for generating an output frequency in response thereto that controls an operating frequency of the AC motor;
- the microelectronic CPU also providing a current regulator that receives current feedback responsive to current supplied to the motor and which controls a PWM inverter that supplies current to the motor;
- and
- wherein the microelectronic CPU is responsive to program instructions in the stored control program to reduce commanded voltage while holding output frequency at a last running value to reduce flux in the motor;
- upon reaching a flux-reduced level, reducing the output frequency by at least 40% and then sensing dc bus voltage to provide a feedback signal that regulates the output frequency as a function of dc bus voltage to provide control of the output frequency down to about 3 Hz.;
- and
- upon reaching a flux-reduced level, the microelectronic CPU providing current commands to the motor current regulation loop to provide braking torque to the motor.
4 more elements
A method of flux-reduced braking of an AC motor, comprising:
- reducing commanded voltage while holding output frequency at a last running value to reduce flux in the motor;
- and
- upon reaching a flux-reduced level:
- reducing the output frequency by a percentage;
- sensing dc bus voltage to provide a feedback signal;
- and
- regulating the output frequency as a function of the dc bus voltage feedback signal to provide control of the output frequency down to a reduced value.
4 more elements
A controller for flux-reduced braking of an AC motor, comprising:
- a processor for executing a stored control program to provide a dc bus voltage regulator that receives a dc reference voltage and a dc feedback voltage and for generating an output frequency in response thereto that controls an operating frequency of the AC motor;
- and
- wherein the processor is responsive to program instructions in the stored control program to:
- reduce commanded voltage while holding output frequency at a last running value to reduce flux in the motor;
- upon reaching a flux-reduced level, reduce the output frequency by a percentage;
- sense dc bus voltage to provide a feedback signal;
- and
- regulate the output frequency as a function of dc bus voltage to provide control of the output frequency down to a reduced value.
5 more elements
Dependencies are inferred from the claim text.