Electric drive retarding system and method
First Claim
1. A retarding system for an electric drive machine having an engine that powers a generator, a rectifier connected to the generator, an inverter, and at least one drive motor connected to the inverter, the retarding system comprising:
- a direct current (DC) link connected to the rectifier and the inverter and including a first DC rail at a first voltage and a second DC rail at a second voltage;
a first contactor switch in electrical communication with the first DC rail;
a second contactor switch in electrical communication with the second DC rail;
a first resistor grid connected in series between the first contactor switch and the second contactor switch; and
a controller disposed to selectively actuate the first contactor switch and the second contactor switch to conduct a waste current through the first resistor grid between the first DC rail and the second DC rail, the waste current being generated by the at least one drive motor when a motion of the electric drive machine is retarded.
1 Assignment
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Accused Products
Abstract
A retarding system for an electric drive machine (100) includes a direct current (DC) link (312), at which a DC voltage is developed, disposed between a rectifier (206) and an inverter (208). A first contactor switch (216) electrically communicates with a first rail of the DC link (312), and a second contactor switch (216) electrically communicates with a second rail of the DC link (312). A first resistor grid (214) is connected in series between the first contactor switch (216) and the second contactor switch (216). The first resistor grid (214) dissipates electrical energy in the form of heat by conducting a current between the first rail and the second rail of the DC link (312) when the first contactor switch (216) and the second contactor switch (216) are closed.
114 Citations
20 Claims
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1. A retarding system for an electric drive machine having an engine that powers a generator, a rectifier connected to the generator, an inverter, and at least one drive motor connected to the inverter, the retarding system comprising:
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a direct current (DC) link connected to the rectifier and the inverter and including a first DC rail at a first voltage and a second DC rail at a second voltage; a first contactor switch in electrical communication with the first DC rail; a second contactor switch in electrical communication with the second DC rail; a first resistor grid connected in series between the first contactor switch and the second contactor switch; and a controller disposed to selectively actuate the first contactor switch and the second contactor switch to conduct a waste current through the first resistor grid between the first DC rail and the second DC rail, the waste current being generated by the at least one drive motor when a motion of the electric drive machine is retarded. - View Dependent Claims (2, 3, 4, 5)
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6. A machine, comprising:
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an engine having an output; a generator connected to the output of the engine and disposed to provide a generator output; a rectifier connected to the generator; an inverter connected to the rectifier; a direct current (DC) link connected to the rectifier and the inverter defining a first rail and a second rail; at least one motor connected to the inverter, the at least one motor connected to at least one drive wheel; a first contactor switch connected to the first rail of the DC link; a second contactor switch connected to the second rail of the DC link; a first resistor grid connected in series between the first contactor switch and the second contactor switch; an inverter circuit disposed in parallel electrical connection with a portion of the first resistor grid, wherein the inverter circuit is arranged to convert a DC voltage that is developed across the portion of the first resistor grid into an alternating current (AC) voltage; an AC motor electrically connected to the converter circuit and disposed to operate by receiving the AC voltage; wherein a flow of power is defined from the generator, to the rectifier, to the inverter, and to the at least one motor when the machine is in a propel mode, and wherein a waste power flow path is defined, at least partially, from the at least one drive wheel, through the at least one motor, the inverter, the first contactor switch, the second contactor switch, the first resistor grid, the inverter circuit, and the AC motor when the machine is in a retarding mode. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method of retarding an electric drive machine having a DC link voltage present between a first DC rail and a second DC rail, comprising:
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determining a magnitude of a retarding command; comparing the magnitude to a threshold value; and activating two contactor switches and conducting an additional current through an additional resistor grid while the magnitude exceeds the threshold value. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification