Reducing inrush current when transformer in electric vehicle is connected to power
First Claim
1. A method of controlling connection of a transformer of an electric vehicle to an alternating voltage supply carried by a trolley wire, the vehicle having a contact pad for electrically connecting the transformer to the trolley wire, the contact pad being moveable between a first position in which the contact pad is held away from electrical contact with the trolley wire and a second position in which the contact pad makes electrical contact with the trolley wire, the method comprising the step of:
- controlling movement of the contact pad towards the trolley wire such that an air gap between the contact pad and trolley wire is electrically broken down to connect the transformer to the trolley wire when a voltage present on the trolley wire is at or near its peak.
5 Assignments
0 Petitions
Accused Products
Abstract
A method of controlling connection of a transformer of an electric vehicle, such as a train locomotive, to an alternating voltage supply carried by a trolley wire, the object being to reduce the transformer inrush current on connection of the transformer to the supply. Movement of a pantograph of the vehicle is judiciously controlled from its lowered position to a raised position so that as the pantograph approaches the trolley wire an arc bridges the air gap between them to consistently connect the electrical transformer of the vehicle to the trolley wire when the voltage present on the wire is at or near its peak. The vehicle'"'"'s power system is controlled such that if the power supply to the trolley wire is lost while the pantograph is raised, the transformer is first isolated from the pantograph and then after the power supply is restored, the pantograph is lowered, re-connected to the transformer and re-raised to reestablish the connection with the trolley wire in the above judiciously controlled manner.
13 Citations
13 Claims
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1. A method of controlling connection of a transformer of an electric vehicle to an alternating voltage supply carried by a trolley wire, the vehicle having a contact pad for electrically connecting the transformer to the trolley wire, the contact pad being moveable between a first position in which the contact pad is held away from electrical contact with the trolley wire and a second position in which the contact pad makes electrical contact with the trolley wire, the method comprising the step of:
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controlling movement of the contact pad towards the trolley wire such that an air gap between the contact pad and trolley wire is electrically broken down to connect the transformer to the trolley wire when a voltage present on the trolley wire is at or near its peak. - View Dependent Claims (2, 3, 4, 5, 6, 7)
re-measuring the voltage on the trolley wire after the switching means is re-opened to detect presence of the supply to the trolley wire, and if the supply is detected while the contact pad is in its second position, sequentially moving the contact pad to the first position, closing the switching means and then moving the contact pad back to the second position.
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8. A power system for an electric vehicle for receiving AC power through a trolley wire, comprising:
an electric motor, a transformer for supplying power to the electric motor, a contact pad for electrically connecting the transformer to the trolley wire, means for moving the contact pad at a controlled rate from a first position in which the contact pad is held away from electrical contact with the trolley wire to a second position in which the contact pad makes electrical contact with the trolley wire, an isolating switch switchable between a closed state in which the transformer is connected to the contact pad and an open state in which the transformer is isolated from the contact pad, and control means for executing logical control of the position of the contact pad in conjunction with the state of the isolating switch such that the switch is actuated to the closed state before the contact pad moves from the first position to the second position, whereby the transformer is connected to a voltage supply on the trolley wire as a supply voltage reaches a peak due to electrical breakdown of an air gap between the trolley wire and the contact pad. - View Dependent Claims (9, 10, 11, 12)
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13. An electric vehicle incorporating a power system for receiving AC power through a trolley wire, comprising:
an electric motor, a transformer for supplying power to the electric motor, a contact pad for electrically connecting the transformer to the trolley wire, means for moving the contact pad at a controlled rate from a first position in which the contact pad is held away from electrical contact with the trolley wire to a second position in which the contact pad makes electrical contact with the trolley wire, an isolating switch switchable between a closed state in which the transformer is connected to the contact pad and an open state in which the transformer is isolated from the contact pad, and control means for executing logical control of the position of the contact pad in conjunction with the state of the isolating switch such that the switch is actuated to the closed state before the contact pad moves from the first position to the second position, whereby the transformer is connected to a voltage supply on the trolley wire as a supply voltage reaches a peak due to electrical breakdown of an air gap between the trolley wire and the contact pad.
Specification