Hybrid power supply system having energy storage device protection circuit
First Claim
1. A hybrid power supply system for delivering power to a load comprising:
- (a) a power generator electrically connectable to said load;
(b) an energy storage device electrically connectable to said load;
(c) a protection circuit in series with said energy storage device, wherein said circuit comprises a first switch adjustable between open and closed positions and a diode in parallel with said switch; and
(d) a controller for controlling relative supply of power to said load from said power generator and said energy storage device, wherein said first switch is controllable by said controller.
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Accused Products
Abstract
This application relates to an energy storage device protection circuit for use in a hybrid system supplying power to an active dynamic DC load, such as an electric vehicle drive. The circuit prevents over-discharge of the energy storage device and ensures that the system will be capable of delivering a minimum acceptable level of power to the load, even when the energy storage device is in a low state of charge or other de-rated mode. The hybrid system includes a power generator such as fuel cell capable of supplying at least the average power value requirements of the load and an energy storage device such as a battery or capacitor capable of supplying at least the difference between the peak power requirements of the load and the average power value. A controller is provided for controlling the relative supply of power to the load from the power generator and the energy storage device. The protection circuit is in series with the energy storage device and may include a first switch controllable by the controller, a diode in parallel with the first switch and optionally a current-limiting impedance in parallel with the first switch. The system may be implemented in lift trucks and the like to prevent overdriving of the vehicle in a low state of charge condition while permitting the operator to safely return the vehicle to a service location. The system regulates the output of the fuel cell in both the normal and de-rated operating modes to avoid load-following operation.
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Citations
26 Claims
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1. A hybrid power supply system for delivering power to a load comprising:
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(a) a power generator electrically connectable to said load;
(b) an energy storage device electrically connectable to said load;
(c) a protection circuit in series with said energy storage device, wherein said circuit comprises a first switch adjustable between open and closed positions and a diode in parallel with said switch; and
(d) a controller for controlling relative supply of power to said load from said power generator and said energy storage device, wherein said first switch is controllable by said controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of controllably delivering power to an active dynamic load having a peak power value and an average power value comprising:
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(a) providing a hybrid power supply system comprising a DC power generator capable of supplying at least said average power value to said load and an energy storage device capable of supplying at least the difference between said peak power value and said average power value to said load;
(b) monitoring the operation of said energy storage device to determine whether said energy storage device is in a normal operating mode or a de-rated operating mode; and
(c) controllably limiting the current discharged from said energy storage device when said energy storage device is determined to be in said de-rated mode. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification