Motor minimum speed start-up circuit for electric motors
First Claim
1. A minimum speed start-up circuit for use in an electric motor vehicle for providing a minimum torque output from the motor when an operator commands the vehicle to accelerate at low motor speeds comprising:
- speed determining means for providing a signal indicative of the present speed of the motor;
demand current generating means for generating operating current to be delivered to the motor to drive the motor for normal operation of the vehicle;
minimum torque demand current generating means for generating a minimum demand current to be delivered to the motor when the operator commands the vehicle to accelerate at a motor speed below a predetermined limit; and
means for selectively supplying the motor with the greater of the operating current or the minimum demand current so that at least a minimum torque is output by the motor when the operator commands the vehicle to accelerate at low speeds.
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Accused Products
Abstract
A minimum speed start-up circuit and method for an electric powered vehicle which ensures a minimum torque output from the motor at low vehicle speeds. The circuit includes a speed determining means for providing a signal indicative of the present speed of the vehicle, a demand current generating means for generating an operating current for delivery to the motor to enable normal vehicle operation, and a minimum torque demand current generating means for generating a minimum demand current for delivery to the motor when the vehicle'"'"'s accelerator is depressed at low vehicle speeds. The start-up circuit selectively supplies the greater of the operating current or the demand current to the motor so that at least a minimum torque is output by the motor.
47 Citations
4 Claims
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1. A minimum speed start-up circuit for use in an electric motor vehicle for providing a minimum torque output from the motor when an operator commands the vehicle to accelerate at low motor speeds comprising:
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speed determining means for providing a signal indicative of the present speed of the motor; demand current generating means for generating operating current to be delivered to the motor to drive the motor for normal operation of the vehicle; minimum torque demand current generating means for generating a minimum demand current to be delivered to the motor when the operator commands the vehicle to accelerate at a motor speed below a predetermined limit; and means for selectively supplying the motor with the greater of the operating current or the minimum demand current so that at least a minimum torque is output by the motor when the operator commands the vehicle to accelerate at low speeds. - View Dependent Claims (2, 3)
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4. A method of providing a minimum torque output from an electric drive motor in an electric motor vehicle when the operator commands the vehicle to accelerate at low motor speeds comprising the steps of:
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a. Receiving an acceleration command from the operator; b. Sensing the amount of current flowing through the motor; c. when the operator demands the vehicle to accelerate at a motor speed below a selected minimum speed, supplying the motor with a minimum torque demand signal to drive the motor at a minimum torque output, the minimum torque demand signal being a function of the received acceleration command and the sensed current flowing through the motor, said minimum torque demand signal being supplied to the motor until the motor reaches a predetermined maximum speed; d. selecting the minimum speed as a first speed when the vehicle is commanded to accelerate after slowing from a higher speed, and as a second, higher speed when the vehicle is commanded to accelerate other than after slowing from a higher speed; and e. supplying the motor with a command signal to drive the motor for normal operations in the absence of the minimum torque demand signal.
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Specification