Method for controlling the motor of a pump involving the determination and synchronization of the point of maximum torque with a table of values used to efficiently drive the motor
First Claim
1. A method of controlling a motor for driving a pump load, the method being practiced in a motor drive and the method comprising:
- testing pump pressure at a beginning and at the end of a pump cycle and comparing average pump pressure to a tolerance factor to determine that average pump pressure within the pump cycle has not changed significantly so as to effect a point of maximum motor torque;
repeatedly sampling a pump pressure that is representative of motor torque over one cycle of operation of the pump;
determining and identifying at least one point of maximum motor torque during said one cycle of operation of the pump;
synchronizing a first value in a table of stored values to the point of maximum motor torque; and
applying speed commands to the motor from the table of stored values after synchronizing to the first value, said values being selected to provide relatively greater speed commands at points of lower motor torque and relatively lesser speed commands at points of higher pump pressure corresponding to higher motor torque, while maintaining at least a base speed command to prevent stalling.
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Accused Products
Abstract
A method for controlling a motor (11) driving a pump (10) using a microcomputer (14) includes repeatedly sampling a parameter representative of motor torque over one cycle of operation of the pump (10), determining at least one point of maximum motor torque during said one cycle of operation of the pump (FIG. 4); applying speed commands to the motor (11) from a table of stored speed values in memory (19), said values being selected to provide relatively greater speed commands at points of lower motor torque and relatively lesser speed commands at points of higher pump pressure corresponding to higher motor torque, while maintaining at least a base speed command to prevent stalling; and synchronizing the first value in the table of stored values to the point of maximum motor torque.
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Citations
14 Claims
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1. A method of controlling a motor for driving a pump load, the method being practiced in a motor drive and the method comprising:
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testing pump pressure at a beginning and at the end of a pump cycle and comparing average pump pressure to a tolerance factor to determine that average pump pressure within the pump cycle has not changed significantly so as to effect a point of maximum motor torque; repeatedly sampling a pump pressure that is representative of motor torque over one cycle of operation of the pump; determining and identifying at least one point of maximum motor torque during said one cycle of operation of the pump; synchronizing a first value in a table of stored values to the point of maximum motor torque; and applying speed commands to the motor from the table of stored values after synchronizing to the first value, said values being selected to provide relatively greater speed commands at points of lower motor torque and relatively lesser speed commands at points of higher pump pressure corresponding to higher motor torque, while maintaining at least a base speed command to prevent stalling. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer program stored in a tangible medium and operable in at least one microcomputer-based motor control system, the computer program comprising:
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instructions for testing for pump pressure at a beginning and at an end of a pump cycle and comparing pump pressure to a tolerance factor to determine that an average pump pressure has not changed so as to effect a point of maximum motor torque; instructions for repeatedly sampling pump pressure representative of motor torque over one cycle of operation of the pump; instructions for determining and identifying at least one point of maximum motor torque during one cycle of operation of the pump; at least one instruction for synchronizing a first value in a table of stored values to the point of maximum motor torque; and instructions for applying speed commands to the motor from a table of stored values after synchronizing to the first value, said values being selected to provide relatively greater speed commands at points of lower pump pressure and relatively lesser speed commands at points of higher pump pressure, while maintaining a base speed command to prevent stalling. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification