초록 ▼

Motor control circuits having solid-state switching elements are commonly used on industrial vehicles such as lift trucks. A short circuit condition in the motor circuit can cause catastrophic failure of the semiconductor switching element. The instant invention detects such a short circuit conditio

Motor control circuits having solid-state switching elements are commonly used on industrial vehicles such as lift trucks. A short circuit condition in the motor circuit can cause catastrophic failure of the semiconductor switching element. The instant invention detects such a short circuit condition and modifies the motor control signals supplied by a chopper circuit to a switching element. The apparatus includes a trigger circuit for receiving the motor control signals and sensing a voltage across the motor produced in response to electrical power delivered from a power supply.

대표청구항 ▼

Apparatus for sensing a short circuit condition of a motor control circuit, comprising: a battery having first and second battery poles; a transistor having an emitter terminal, a base terminal, and a collector terminal connected to one of said battery first and second poles; a motor having a first

Apparatus for sensing a short circuit condition of a motor control circuit, comprising: a battery having first and second battery poles; a transistor having an emitter terminal, a base terminal, and a collector terminal connected to one of said battery first and second poles; a motor having a first motor terminal connected to the other of said battery first and second poles, and a second motor terminal connected to said transistor emitter terminal; chopper means for controllably producing motor control signals; clock means for periodically producing a reset signal; a first logic gate having a second input terminal, an output terminal, and a first input terminal connected to said transistor emitter terminal; a latch having an output terminal, a first input terminal connected to said first logic gate output terminal, and a second input terminal connected to said clock means; and a second logic gate having a first input terminal connected to said latch output terminal, a second input terminal connected to said chopper means, and an output terminal connected to said transistor base terminal and said first logic gate second input terminal.