Bypass contactor circuit

Claim 2

In a time-ratio control system for controlling the operation of an electric vehicle and including a gated thyristor, control means for commutating the thyristor and for varying the markspace ratio thereof, and bypass means operable to shunt the thyristor, said bypass means requiring a first time period for complete energization thereof, timer means operable after a second period of time to inhibit commutation of the thyristor and to commence energization of the bypass means; switching means operably coupled to the control means for energizing said timer means in response to the attainment by said control means of a predetermined state; and override means for maintaining the energization of the bypass means for at least said first time period despite the retreat of said control means from said predetermined state after the expiration of said second predetermined time period.

Claim 3

The invention defined in claim 1, wherein said control means includes manually-displaceable means, said switching means being operatively coupled to said manually displaceable means.

Claim 4

The invention defined in claim 2, wherein the thyristor is an SCR.

Claim 5

The invention defined in claim 3, wherein said override means is coupled in circuit with said switching means, and maintains the effect thereof for a predetermined period regardless of displacement of said manually-displaceable means after said second predetermined period of time.

Claim 6

In a control system for electric vehicle including a thyristor for intermittently coupling and decoupling a traction motor to a source of dc power, a gating control for energizing and deenergizing the thyristor, speed control means coupled to the gating control for varying the mark-space ratio of conductivity of the thyristor, and a bypass contactor coupled in shunt about the thyristor, said bypass contactor including a pair of contacts and a control winding and requiring a first period of time after application of power to said winding for closure of the contacts, the improvement comprising: timing means coupled to the gating control and bypass contactor and energizable to inhibit commutation of the thyristor and to apply power to the winding of said contactor a second, predetermined period of time after application of an enabling signal thereto: switching means associated with the speed control means for energizing said timer in response to the attainment by said speed control means of a predetermined status; and override means operated by said timer to prevent the removal of power from said control winding for at least said first period of time after the application of power to said winding.

Claim 7

In a control system for electric vehicle including a thyristor for intermittently coupling and decoupling a traction motor to a source of dc power, a gating control for energizing and deenergizing the thyristor, speed control means coupled to the gating control for varying the mark-space ratio of conductivity of the thyristor, and a bypass contactor coupled in shunt about the thyristor, said bypass contactor including a pair of contacts and a control winding and requiring a first period of time after application of power to said winding for closure of the contacts, the improvement comprising: timing means coupled to the gating control and bypass contactor and energizable to inhibit commutation of the thyristor and to apply power to the winding of said contactor a second, predetermined period of time after application of an enabling signal thereto: switching means associated with the speed control means for energizing said timer in response to the attainment by said speed control means of a predetermined status; and override means operated by said timer to prevent the removal of power from said control winding for at least said first period of time after the application of power to said winding.

Claim 8

The invention defined in claim 5, wherein said speed control comprises a variable resistance, said switching means being operated when said speed control is manually displaced to a predetermined position.

Claim 9

The invention defined in claim 6, wherein said predetermined position corresponds to the maximum speed adjustment.

Claim 10

The invention defined in claim 6, wherein said override means is operable to continue the effect of said switching means upon said timer.