Power supply apparatus

• US 20050231175A1
• Filed: 03/18/2005
• Published: 10/20/2005
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Takahashi, Yoshiaki, Furukawa, Kimihiko, Seo, Kazuhiro
• Granted Patent: US 7,071,698 B2
• Time in Patent Office: Days
• US Class Current: 323/211
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 19/257 using analogue/digital converters of the type with comparison of different reference values with the value of voltage or current, e.g. using step-by-step method

Abstract

A power supply apparatus according to the present invention includes a battery and a voltage detection circuit for detecting the voltage of the battery. The voltage detection circuit includes a differential amplifier which has a first input terminal for receiving a voltage based on the voltage of the battery and a second input terminal for receiving a predetermined triangular wave and outputs a rectangular wave with a pulse width modulated according to the voltage based on the voltage of the battery and a predetermined offset voltage, and an offset circuit which supplies the offset voltage to one of the first input terminal and the second input terminal so that the differential amplifier outputs a particular rectangular wave according to the offset voltage even when the voltage based on the voltage of the battery which is supplied to the first input terminal is 0.

Claims

1. A power supply apparatus comprising:

a battery; and

a voltage detection circuit for detecting the voltage of the battery, wherein

the voltage detection circuit includes;

a differential amplifier which has a first input terminal for receiving a voltage based on the voltage of the battery and a second input terminal for receiving a particular triangular wave and outputs a rectangular wave with a pulse width modulated according to the voltage based on the voltage of the battery and a predetermined offset voltage; and

an offset circuit which supplies the offset voltage to one of the first input terminal and the second input terminal so that the differential amplifier outputs a predetermined rectangular wave according to the offset voltage even when the voltage based on the voltage of the battery which is supplied to the first input terminal is 0.

2. The power supply apparatus according to claim 1, wherein

the voltage detection circuit further includes:

an insulating coupler which transmits the rectangular wave output from the differential amplifier in an insulating manner;

an integration circuit which integrates an output signal from the insulating coupler; and

an A/D converter which converts an analog signal output from the integration circuit into a digital signal.

3. The power supply apparatus according to claim 2, wherein

the output of the insulating coupler is connected to the integration circuit through a connector.

4. The power supply apparatus according to claim 1, wherein

the battery is constituted by a plurality of cells connected in serial, wherein one of connection points of the plurality of cells is supplied with a predetermined reference potential, and

the power supply apparatus comprises two voltage detection circuits, wherein one of the voltage detection circuits detects a voltage at a positive-side output terminal of the battery relative to said one connection point and the other voltage detection circuit detects a voltage at a negative-side output terminal of the battery relative to said one connection point.

5. The power supply apparatus according to claim 1, further comprising:

a triangular-wave generation circuit which generates the triangular wave; and

a switching power supply circuit which supplies a power supply voltage for the triangular-wave generation circuit, wherein

the switching power supply circuit includes an activation switch which separates the triangular-wave generation circuit as a load for a predetermined time period, during the activation of the switching power supply circuit.

6. The power supply apparatus according to claim 1, further comprising:

a triangular-wave generation circuit which generates the triangular wave; and

a switching power supply circuit which supplies electric power as a power supply to the triangular-wave generation circuit, wherein

the switching power supply circuit includes an activation switch capable of turning on and off the supply of electric power to the triangular-wave generation circuit which is a load, and

the activation switch is controlled such that the supply of electric power to the triangular-wave generation circuit is off for a predetermined time period during the activation of the switching power supply circuit.