Retarding energy calculator for an electric drive machine
First Claim
1. A machine having a hybrid-electric drive system, the hybrid-electric drive system including an engine connected to a generator, a rectifier connected to the generator and to a direct current (DC) link, an inverter connected to the DC link and to at least one drive motor, the machine further comprising:
- a first resistor grid connected in series with two automatic switches, each of the two automatic switches disposed between the first resistor grid and the DC link, wherein each automatic switch is responsive to a switch signal;
a second resistor grid connected in series with a chopper and in parallel with the DC link, the chopper disposed between the second resistor grid and the DC link, wherein the chopper is responsive to a duty cycle command;
a motor operating a blower, the motor connected across a portion of the first resistor grid via a motor inverter, wherein the motor is responsive to an activation command;
an electronic controller disposed to generate the switch signal, the duty cycle command, and the activation command when a net energy input into at least one of the first resistor grid and the second resistor grid exceeds a threshold value, the electronic controller further disposed to calculate first and second power inputs for power dissipated by the first and second resistor grids respectively, a total power input based on the first and second power inputs, a first power output for power consumed by the motor, a second power output for power dissipated by conduction from the first and second resistor grids, a third power output for power dissipated by free convection from the first and second resistor grids, a fourth power output for power dissipated by forced convection from the first and second resistor grids when the motor is active, and a total power output that is based on the first, second, third, and fourth power outputs, and to calculate a difference between total power input and total power output, integrate the difference over time, and activate a cooling sub-routine when the net power difference exceeds the threshold value.
1 Assignment
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Accused Products
Abstract
A cooling system for a retarding system of an electric drive machine (100) includes a direct current (DC) link having first and second rails. A first resistor grid (214) is selectively placed in circuit between the rails by an automatic switch (216) in response to a switch (216) signal. A second resistor grid (218) is selectively placed in circuit between the rails by a chopper circuit (220) connected in series with the second resistor grid (218). The chopper modulates a current passing therethrough based on a duty cycle. A motor (336) is in parallel electrical connection across a portion of the first resistor grid (214) and operates in response to a motor (336) signal. An electronic controller (400) calculates a net energy during operation and adjusts the switch (216) signal, the duty cycle, and the motor (336) signal to close the automatic electrical switch (216) and operate the motor (336) when the net energy exceeds a threshold value.
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Citations
15 Claims
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1. A machine having a hybrid-electric drive system, the hybrid-electric drive system including an engine connected to a generator, a rectifier connected to the generator and to a direct current (DC) link, an inverter connected to the DC link and to at least one drive motor, the machine further comprising:
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a first resistor grid connected in series with two automatic switches, each of the two automatic switches disposed between the first resistor grid and the DC link, wherein each automatic switch is responsive to a switch signal; a second resistor grid connected in series with a chopper and in parallel with the DC link, the chopper disposed between the second resistor grid and the DC link, wherein the chopper is responsive to a duty cycle command; a motor operating a blower, the motor connected across a portion of the first resistor grid via a motor inverter, wherein the motor is responsive to an activation command; an electronic controller disposed to generate the switch signal, the duty cycle command, and the activation command when a net energy input into at least one of the first resistor grid and the second resistor grid exceeds a threshold value, the electronic controller further disposed to calculate first and second power inputs for power dissipated by the first and second resistor grids respectively, a total power input based on the first and second power inputs, a first power output for power consumed by the motor, a second power output for power dissipated by conduction from the first and second resistor grids, a third power output for power dissipated by free convection from the first and second resistor grids, a fourth power output for power dissipated by forced convection from the first and second resistor grids when the motor is active, and a total power output that is based on the first, second, third, and fourth power outputs, and to calculate a difference between total power input and total power output, integrate the difference over time, and activate a cooling sub-routine when the net power difference exceeds the threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of controlling a temperature of one or more resistor grids used to retard an electric drive machine, the method comprising:
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evaluating a total power input to the one or more resistor grids; evaluating a total power output from the one or more resistor grids; calculating a net power difference for power in the one or more resistor grids by subtracting the total power output from the total power input; integrating the net power difference over time; and activating a cooling sub-routine when an integral of the net power difference exceeds a threshold. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification