MOTOR DRIVE SYSTEM
First Claim
1. A motor drive system for driving an AC motor, comprising:
- a motor drive circuit being capable of bidirectionally supplying and receiving a power to and from the AC motor, and supplying a drive power to said AC motor; and
motor control means for controlling an operation of said motor drive circuit to perform a consuming operation of consuming a surplus power determined depending on a state of said motor drive system by said AC motor, and to perform a follow-up operation of causing an output torque to follow changes in torque command value while keeping said consuming operation when said torque command value to said AC motor changes during said consuming operation, whereinsaid motor control means includes;
current command producing means for producing, as a current command, a set of a d-axis current command value and a q-axis current command value corresponding to an amplitude and a phase of a motor current causing the output torque of said AC motor to match with said torque command value and causing said surplus power to be consumed by said AC motor, andcurrent control means for controlling the operation of said motor drive circuit to generate the motor current in accordance with said current command produced by said current command producing means.
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Accused Products
Abstract
In a drive system of an AC motor in which a motor current is feedback-controlled, a motor current command is produced in a normal operation according to a torque command value on an optimum efficiency characteristic line so as to select an optimum current phase maximizing an output torque with a constant motor current amplitude. Conversely, when the AC motor produces an excessively generated power exceeding a regeneratable power quantity of the AC motor, a consuming operation is performed for intentionally increasing the power loss in the AC motor. In the consuming operation, the motor current command is produced according to the torque command value on a loss increase characteristic line to change the current phase from the above optimum value. Thereby, the power loss in the AC motor can be increased to consume the surplus power without causing instability in the motor control.
54 Citations
13 Claims
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1. A motor drive system for driving an AC motor, comprising:
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a motor drive circuit being capable of bidirectionally supplying and receiving a power to and from the AC motor, and supplying a drive power to said AC motor; and motor control means for controlling an operation of said motor drive circuit to perform a consuming operation of consuming a surplus power determined depending on a state of said motor drive system by said AC motor, and to perform a follow-up operation of causing an output torque to follow changes in torque command value while keeping said consuming operation when said torque command value to said AC motor changes during said consuming operation, wherein said motor control means includes; current command producing means for producing, as a current command, a set of a d-axis current command value and a q-axis current command value corresponding to an amplitude and a phase of a motor current causing the output torque of said AC motor to match with said torque command value and causing said surplus power to be consumed by said AC motor, and current control means for controlling the operation of said motor drive circuit to generate the motor current in accordance with said current command produced by said current command producing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification