Hybrid power supply system

• US 20070273209A1
• Filed: 01/16/2003
• Published: 11/29/2007
• Est. Priority Date: 01/17/2002
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Endou, Takayoshi
• Granted Patent: US 7,439,631 B2
• Time in Patent Office: Days
• US Class Current: 307/45
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/50 using propulsion power supplied by batteries or fuel cells
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

It is an object of the present invention to provide a high efficiency hybrid power supply system that permits a power type power supply device such as a capacitor to be utilized effectively, and that makes it possible to even the burden on an energy type power supply device such as a storage cell. A capacitor 21 is connected to system voltage lines 26 and 27 which are connected to a load 30, and a body formed by a serial connection between a large-capacity storage cell 22 and the output terminal of a voltage controller 23 is connected in parallel with this capacitor 21. The voltage Vb of the storage cell 22 is substantially constant. The voltage controller 23 is a DC/DC converter, for example, the output voltage Vv of which is variable. A system controller 25 changes the system voltage Vs by changing the output voltage Vv of the voltage controller 23. When a large amount of electric power is to be supplied to the load 30, energy is rapidly discharged from the capacitor 21 and supplied to the load 30 by lowering the system voltage Vs. When a large amount of electric power is to be fed back from the load 30, energy from the load 30 is rapidly absorbed by the capacitor 21 by raising the system voltage Vs.

Claims

1. A hybrid power supply system, comprising:

system voltage lines which are connected to a load;

an energy type power supply device connected to the system voltage lines;

a power type power supply device connected to the system voltage lines; and

system voltage control means that change the voltage of the power type power supply device by changing the voltage of the system voltage lines, and thus allow electric power to be outputted from the power type power supply device to the system voltage lines and electric power to be absorbed by the power type power supply device from the system voltage lines.

2. The hybrid power supply system according to claim 1, wherein the system voltage control means change the system voltage in accordance with the electric power required by the load.

3. The hybrid power supply system according to claim 1, wherein the system voltage control means reduce the system voltage when electric power is to be supplied to the load, and raise the system voltage when electric power is to be fed back from the load.

4. The hybrid power supply system according to claim 1, wherein the system voltage control means comprise a voltage controller having a variable output voltage;

the output terminal of the voltage controller is serially connected to the energy type power supply device; and

a body formed by the serial connection between the energy type power supply device and the output terminal of the voltage controller is connected to the system voltage lines in parallel with the power type power supply device.

5. The hybrid power supply system according to claim 4, further comprising:

an additional energy type power supply device which is provided separately from the energy type power supply device in order to supply electric power to an input terminal of the voltage controller; and

a power supply defect detector that detects a defect in the electric power supply capacity of the energy type power supply device,

wherein, when the defect is detected by the power supply defect detector, the system voltage control means operate so that the defective energy type power supply device is substantially not used and so that the output voltage of the voltage controller that then operates under the electric power from the additional power supply device is applied to the system voltage lines substantially directly.

6. The hybrid power supply system according to claim 4, wherein the system voltage control means further comprise a plurality of power supply modules connected in parallel with the system voltage lines, and each power supply module is constituted by a body formed by a serial connection between the energy type power supply device and the output terminal of the voltage controller.

7. The hybrid power supply system according to claim 1, wherein the system voltage control means further comprise a plurality of energy type power supply devices which are connected to the system voltage lines, and switches that selectively connect the plurality of energy type power supply devices to the system voltage lines in series or in parallel;

and wherein the system voltage control means change the system voltage depending on whether the plurality of energy type power supply devices are connected in series or in parallel.

8. A hybrid power supply system, comprising:

output terminals;

a serial/parallel chopper circuit that comprises a plurality of energy type power supply devices and switching elements, which serial/parallel chopper circuit causes the plurality of energy type power supply devices to be alternately connected in series and in parallel between the output terminals as a result of the ON/OFF operation of the switching elements, and outputs the output voltage to the output terminals, this output voltage being at a level that corresponds to the duty of the switching elements;

a power type power supply device connected between the output terminals; and

a controller that performs an ON/OFF operation by driving the switching elements of the serial/parallel chopper circuit and increases/decreases the level of the output voltage by controlling the duty of the switching elements.

9. The hybrid power supply system according to claim 8, wherein the serial/parallel chopper circuit further comprises a current path for feeding back electrical energy from. the output terminals to the energy type power supply devices.

10. The hybrid power supply system according to claim 9, wherein the serial/parallel chopper circuit further comprises:

an inductor that serves to temporarily store the electrical energy fed back from the output terminals and to discharge the stored electrical energy to the energy type power supply device; and

current control means for controlling the current flowing in the inductor so that electrical energy is stored and then discharged by the inductor.

11. The hybrid power supply system according to claim 8, wherein the serial/parallel chopper circuit further comprises current paths for feeding back electrical energy from the output terminals to the energy type power supply devices individually.

12. The hybrid power supply system according to any one of claims 9 to 11, wherein the serial/parallel chopper circuit further comprises current control means that serve to control the size of the recharge current for the energy type power supply devices when electrical energy is fed back from the output terminals to the energy type power supply devices.