Hybrid power supply device

Abstract

A hybrid power supply device is provided with a fuel cell, an electric storage device that is connected in parallel to the fuel cell via a switch, and a control circuit that controls connection between output terminals of the fuel cell and the electric storage device by controlling on/off of the switch. Here, the control circuit controls the connection between the output terminals based on an output current of the fuel cell, and disconnects the output terminals when the output current of the fuel cell becomes equal to or smaller than a predetermined lower limit current while the output terminals are connected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block configuration diagram of the hybrid power supply device (the power supply device) according to an embodiment of the present invention;

FIG. 2 is a configuration diagram schematically showing one single cell that is a component of the fuel cell shown in FIG. 1;

FIG. 3 is a graph showing the output characteristics of the fuel cell shown in FIG. 1;

FIG. 4 is a graph showing a stable operating region and an unstable operating region of the fuel cell shown in FIG. 1;

FIG. 5 is a graph showing how the output characteristics of the fuel cell shown in FIG. 1 change as the fuel concentration changes;

FIG. 6 is a graph illustrating the operation of the control circuit shown in FIG. 1;

FIG. 7 is a diagram schematically showing how the fuel cartridge shown in FIG. 2 is replaced;

FIG. 8 is a diagram showing an example of the internal configuration of the control circuit shown in FIG. 1;

FIG. 9 is a diagram illustrating the operation of the control circuit shown in FIG. 1;

FIG. 10 is a diagram showing the internal configuration of the control circuit shown in FIG. 1; and

FIG. 11 is a diagram illustrating a method of restoring the fuel concentration of the fuel cell shown in FIG. 1.

Claims

1. A hybrid power supply device, comprising: a fuel cell;an electric storage device that is connected in parallel to the fuel cell via a switch; anda control circuit that controls connection between output terminals of the fuel cell and the electric storage device by controlling on/off of the switch, wherein the control circuit controls the connection between the output terminals based on an output current of the fuel cell, anddisconnects the output terminals when the output current of the fuel cell becomes equal to or smaller than a predetermined lower limit current while the output terminals are connected.

2. The hybrid power supply device of claim 1, further comprising: a voltage detector that detects an output voltage of the electric storage device, whereinthe lower limit current is determined in accordance with the output voltage of the electric storage device.

3. The hybrid power supply device of claim 1, further comprising: a replenishment detecting portion that detects whether the fuel cell is replenished with fuel or not, whereinwhen fuel replenishment is detected after the output terminals are disconnected as a result of the output current of the fuel cell becoming equal to or smaller than the lower limit current, the control circuit restores the connection between the output terminals.

4. The hybrid power supply device of claim 1, wherein the hybrid power supply device is so configured that a fuel cell unit built with the fuel cell and fuel for the fuel cell can be replaced,the hybrid power supply device further comprises a replacement detecting portion that detects whether the fuel cell unit is replaced or not, andwhen replacement of the fuel cell unit is detected after the output terminals are disconnected as a result of the output current of the fuel cell becoming equal to or smaller than the lower limit current, the control circuit restores the connection between the output terminals.

5. The hybrid power supply device of claim 1, further comprising: a voltage detector that detects an output voltage of the electric storage device, whereinthe control circuit disconnects the output terminals when the detected output voltage becomes equal to or higher than a predetermined first voltage while the output terminals are connected.

6. The hybrid power supply device of claim 1, further comprising: a voltage detector that detects an output voltage of the electric storage device, whereinwhen the detected output voltage becomes equal to or higher than a predetermined first voltage while the output terminals are connected, the control circuit disconnects the output terminals, and then, when the detected output voltage becomes equal to or lower than a predetermined second voltage that is lower than the first voltage, the control circuit restores the connection between the output terminals.

7. A hybrid power supply device, comprising: a fuel cell;an electric storage device that is connected in parallel to the fuel cell via a switch;a control circuit that controls connection between output terminals of the fuel cell and the electric storage device by controlling on/off of the switch; anda voltage detector that detects an output voltage of the electric storage device, whereinwhen the detected output voltage becomes equal to or higher than a predetermined first voltage while the output terminals are connected, the control circuit disconnects the output terminals, and then, when the detected output voltage becomes equal to or lower than a predetermined second voltage that is lower than the first voltage, the control circuit restores the connection between the output terminals.