Method for inhibiting wheel slip in an electric alternating current induction motor powered vehicle
First Claim
1. A method for inhibiting wheel slip in an electric alternating current induction motor powered vehicle including electric power control means comprising the steps of:
- determining a vehicle speed;
converting the vehicle speed to a torque command signal;
estimating relatively positive and negative torque command limits using the vehicle speed and a maximum allowable vehicle speed;
comparing the torque command signal to the positive and negative torque command limits to develop a torque reference signal limited to a maximum value corresponding to a respective one of the positive and negative torque command limits;
subtracting the magnitude of the signal corresponding to actual motor torque from the magnitude of the torque reference signal to develop a torque error signal;
converting the torque error signal to a corresponding torque regulator signal;
summing the torque regulator signal with the torque reference signal to develop a motor torque signal;
converting the motor torque signal to a corresponding frequency command signal; and
obtaining, from the electric power control means, an excitation frequency for the induction motor corresponding to the frequency command signal.
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Abstract
A method for inhibiting wheel slip in an electric alternating current induction motor powered vehicle responsive to a frequency command signal and to a signal representative of actual motor torque for establishing a corresponding excitation frequency for the induction motor develops the frequency command signal from a torque command signal. The method compares the torque command signal to selectively variable relatively positive and negative torque command limits to develop a torque reference signal. The magnitude of the signal corresponding to actual motor torque is subtracted from the magnitude of the torque reference signal to develop a torque error signal, which error signal is then converted to a corresponding torque regulator signal. The torque regulator signal is summed with the torque reference signal to develop a motor torque signal and the motor torque signal is then converted to a corresponding frequency command signal. This method assures that motor torque does not exceed the torque which would result in slipping or sliding and thus prevents the initiation of a wheel slip or slide.
79 Citations
11 Claims
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1. A method for inhibiting wheel slip in an electric alternating current induction motor powered vehicle including electric power control means comprising the steps of:
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determining a vehicle speed; converting the vehicle speed to a torque command signal; estimating relatively positive and negative torque command limits using the vehicle speed and a maximum allowable vehicle speed; comparing the torque command signal to the positive and negative torque command limits to develop a torque reference signal limited to a maximum value corresponding to a respective one of the positive and negative torque command limits; subtracting the magnitude of the signal corresponding to actual motor torque from the magnitude of the torque reference signal to develop a torque error signal; converting the torque error signal to a corresponding torque regulator signal; summing the torque regulator signal with the torque reference signal to develop a motor torque signal; converting the motor torque signal to a corresponding frequency command signal; and obtaining, from the electric power control means, an excitation frequency for the induction motor corresponding to the frequency command signal.
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2. A method for inhibiting wheel slip in an electric alternating current (AC) induction motor powered vehicle, the vehicle including excitation control means for supplying controlled frequency excitation to motors driving the vehicle, the method comprising the steps of:
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determining actual vehicle speed; selecting a speed limiting value from the most limiting of (1) a sum of actual vehicle speed converted to actual wheel speed plus a desired wheel slip and (2) a rate of change of wheel speed; comparing actual wheel speed to the speed limiting value; and maintaining actual wheel speed less than the speed limiting value by varying excitation frequency in response to said comparing step. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification