Importance

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Abstract

Motor control systems are commonly associated with motors found on electric industrial vehicles, such as lift trucks. Advantageously, the control of such motors should be optimized such that current is timely supplied to the motors in conjunction with selection of the appropriate motor direction. The instant apparatus 10 includes a logic device 24 for receiving speed and direction demand signals from respective speed and direction selection devices 20,22. The logic device 24 responsively produces respective motor speed and direction command signals. A motor control device 26 receives the command signals and directs the electrical current from a power source 18 through the motor 12. A transducer device 38 senses the actual direction of electrical current flow through the motor 12 and produces responsive feedback signals. The logic device 24 produces at least one motor direction interrogation pulse in response to receiving the speed and direction demand signals and prior to delivering the motor command signals. The interrogation pulse directs a small amount of electrical current from the power source 18 through the motor 12, insufficient to actually cause rotation of the motor 12. The logic device 24 then compares the direction demand signals and the direction feedback signals and determines if and when command signals can properly be delivered to the motor control device 26.

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First Claim