Electric vehicle protection scheme

• US 4,449,080 A
• Filed: 05/27/1982
• Issued: 05/15/1984
• Est. Priority Date: 05/27/1982
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Konrad, Charles E., Clark, deceased, Robert C.
• Primary Examiner(s): Dobeck, B.
• Assistant Examiner(s): Evans, Arthur G.
• Application Number:
  US06/382,477
• Time in Patent Office: 719 Days
• Field of Search: 318/139, 318/264, 318/272, 318/332, 318/345 R, 318/345 A, 318/434, 318/474, 318/506, 361/33, 361/90, 361/91, 361/92, 361/88, 361/86, 307/125, 307/132 E, 307/130
• US Class Current: 318/139
• CPC Class Codes: H02H 7/0838 with H-bridge circuit
• CPC Class Codes: Y10S 388/903 Protective, e.g. voltage or current limit
• CPC Class Codes: Y10S 388/92 Chopper

Abstract

A fault detection and inhibit circuit for a power control unit in an electric traction motor propelled vehicle of the type wherein the power control unit includes a chopper circuit and a bypass contactor for shunting the chopper circuit when its percent conduction exceeds a relatively high value and a main contactor for connecting the chopper circuit and motor to a power source. The circuit assures that neither the main contactor, the bypass contactor nor the chopper circuit are in a shorted condition before permitting the application of power to the system. In the event of a running failure, the circuit prevents restarting until the failed condition has recovered.

Claims

1. A fault detection and inhibit circuit for a power control unit in an electric traction motor propelled vehicle, the control unit including a chopper circuit for regulating power to the motor and a bypass contactor for shunting the chopper circuit when the percent conduction time of the chopper circuit exceeds a predetermined value, and a main contactor for connecting the motor, the chopper circuit and a power source in a series current path, comprising;

(a) a first voltage divider connected in parallel with the power source;

(b) means for connecting an intermediate point of said first voltage divider to a point intermediate the main contactor and the bypass contactor;

(c) means for comparing the voltage at said intermediate point of said first voltage divider to a predetermined range of voltage values; and

(d) means for inhibiting the operation of the main contactor when said intermediate point voltage is outside said predetermined range of voltage values.

2. The circuit of claim 1 wherein:

said traction motor is a separately excited motor having parallel connected armature and field windings;

said chopper circuit is connected in series with the armature winding; and

a current regulator, for regulating field winding current, is connected in series with the field winding between the point intermediate the main contactor and the bypass contactor and a terminal of the power source.

3. The circuit of claim 1 or 2 wherein said comparing means comprises:

(a) a second voltage divider connected across the power source;

(b) a first voltage comparator having a first input terminal connected to a relatively high voltage top point on said second voltage divider and having a second input terminal connected to said intermediate point on said first voltage divider, said first comparator providing a set signal when said intermediate point voltage exceeds the voltage at said first input terminal;

(c) a second voltage comparator having a first input terminal connected to a relatively low voltage top point on said second voltage divider and having a second input terminal connected to said intermediate point on said first voltage divider, said second comparator providing a set signal when said intermediate point voltage is less than the voltage at said first input terminal; and

(d) means for coupling said set signal from said first and said second comparators to said inhibiting means.