Motor drive control circuit
First Claim
1. A PWM motor drive control circuit for an electric power steering system, comprising:
- a bridge circuit having a pair of input terminals which are adapted to be connected to a DC electric power source, a pair of output terminals adapted to be connected to an electric motor, and four arms each defined by a transistor;
a main control unit for producing a first continual direction control signal for activating a selected one of said transistors, and a torque control signal of a variable duty ratio for activating the transistor diametrically opposed to said selected transistor to activate said electric motor in a desired direction at a desired torque according to a steering command signal supplied thereto;
a sub control unit for exclusively producing a second direction control signal according to said steering command signal; and
a gate drive control circuit for transmitting said first direction control signal and said torque control signal to said diametrically opposed transistors only when said first direction control signal produced by said primary control unit coincides with said second direction signal produced by said sub control unit.
1 Assignment
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Accused Products
Abstract
A PWM motor drive control circuit for an electric power steering system, comprising: a bridge circuit having four arms each defined by a transistor; a main control unit for producing a continual direction control signal and a torque control signal of a variable duty ratio to activate the electric motor in a desired direction at a desired torque according to a steering command signal supplied thereto; a sub control unit for producing a second direction control signal according to the steering command signal; and a gate drive control circuit for transmitting the first direction control signal and the torque control signal to the transistors only when the first direction control signal produced by the primary control unit coincides with the second direction control signal produced by the sub control unit. Thereby, the reliability of an electric motor powered steering system can be improved with a simple circuit structure even when the torque control signal consists of an extremely high frequency variable duty ratio signal.
99 Citations
12 Claims
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1. A PWM motor drive control circuit for an electric power steering system, comprising:
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a bridge circuit having a pair of input terminals which are adapted to be connected to a DC electric power source, a pair of output terminals adapted to be connected to an electric motor, and four arms each defined by a transistor; a main control unit for producing a first continual direction control signal for activating a selected one of said transistors, and a torque control signal of a variable duty ratio for activating the transistor diametrically opposed to said selected transistor to activate said electric motor in a desired direction at a desired torque according to a steering command signal supplied thereto; a sub control unit for exclusively producing a second direction control signal according to said steering command signal; and a gate drive control circuit for transmitting said first direction control signal and said torque control signal to said diametrically opposed transistors only when said first direction control signal produced by said primary control unit coincides with said second direction signal produced by said sub control unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A PWM motor drive control circuit for an electric power steering system, comprising:
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a bridge circuit having a pair of input terminals which are adapted to be connected to a DC electric power source, a pair of output terminals adapted to be connected to an electric motor, and four arms each defined by a transistor; a main control unit for producing a first continual direction control signal for activating a selected one of said transistors, and a torque control signal of a variable duty ratio for activating the transistor diametrically opposed to said selected transistor to activate said electric motor in a desired direction at a desired torque according to a steering command signal supplied thereto; a sub control unit for exclusively producing, as the only outputs thereof, at least one second direction control signal according to said steering command signal; and a gate drive control circuit for transmitting said first direction control signal and said torque control signal to said diametrically opposed transistors only when said first direction control signal produced by said primary control unit coincides with said second direction signal produced by said sub control unit.
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Specification