Power supply device and illumination device for vehicle using same

• US 9,376,056 B2
• Filed: 10/29/2013
• Issued: 06/28/2016
• Est. Priority Date: 10/31/2012
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Ueno, Masatoshi, Nakamura, Toshiaki, Kato, Kazuya, Kichima, Masashi, Nishikawa, Masahiro
• Primary Examiner(s): Pham, Thai
• Assistant Examiner(s): Chan, Wei
• Application Number:
  US14/438,623
• Publication Number:
  US 20150291088A1
• Time in Patent Office: 973 Days
• Field of Search: 315/362, 315/307, 315/247, 315/224, 315/289, 315/291, 315/DIG.5, 315/DIG.7
• US Class Current: 1/1
• CPC Class Codes: B60Q 3/00 Arrangement of lighting devices for vehicle interiors; Lighting devices specially adapted for vehicle interiors
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02H 3/16 responsive to fault current to earth, frame or mass with balanced or differential arrangement H02H3/26 ; monitoring earth connection H02H5/105
• CPC Class Codes: H02H 3/243 for DC systems
• CPC Class Codes: H02H 7/122 for inverters, i.e. dc/ac converters
• CPC Class Codes: H02H 7/1225 responsive to internal faults, e.g. shoot-through avoiding shoot-through H02M1/38
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode

Abstract

A power supply device includes a DC power supply circuit configured to output DC power, and a ground-fault determining circuit configured to determine presence or absence of a ground fault at a post-stage of the DC power supply circuit. The ground-fault determining circuit includes a capacitor having an end that is connected with ground, and a diode including an anode and a cathode. The anode is connected with another end of the capacitor, and the cathode is connected with an output end on a high voltage side of the DC power supply circuit. The ground-fault determining circuit further includes a constant voltage source configured to charge the capacitor with a prescribed charging voltage, and a comparator as a determining portion configured to determine presence of the ground fault when a voltage across the capacitor falls below a prescribed determination reference voltage lower than the prescribed charging voltage.

Claims

1. A power supply device, comprising:

a DC power supply circuit configured to output DC power; and

a ground-fault determining circuit configured to determine presence or absence of a ground fault at a post-stage of the DC power supply circuit,

the ground-fault determining circuit comprising;

a capacitor, of which an end being connected with ground;

a diode including an anode and a cathode, the anode being connected with another end of the capacitor, the cathode being connected with an output end on a high voltage side of the DC power supply circuit;

a determining portion configured to determine the presence or absence of the ground fault based on a voltage across the capacitor; and

a constant voltage source configured to charge the capacitor with a prescribed charging voltage,

the prescribed charging voltage being lower than an output voltage from the DC power supply circuit in a state where the ground fault is absent and power supplying is normally performed from the DC power supply circuit to a load, and

the determining portion being configured to determine the presence of the ground fault when the voltage across the capacitor falls below a prescribed determination reference voltage that is lower than the prescribed charging voltage.

2. The power supply device according to claim 1, wherein when the ground-fault determining circuit determines the presence of the ground fault, the power supply device is configured to stop the power supplying from the DC power supply circuit to the load.

3. The power supply device according to claim 1, wherein the prescribed charging voltage is higher than a minimum value of an output voltage from the DC power supply circuit in a state where the ground fault is present at the post-stage of the DC power supply circuit.

4. The power supply device according to claim 1, further comprising:

a resistor for charging, electrically connected across the constant voltage source and the capacitor; and

a resistor for discharging, connected in series with the diode,

the resistor for charging having a resistance value higher than a resistance value of the resistor for discharging.

5. The power supply device according to claim 1 further comprising a cut-off circuit configured to cut off the power supplying from the DC power supply circuit to the load, when the ground-fault determining circuit determines the presence of the ground fault.

6. The power supply device according to claim 5, wherein the cut-off circuit includes a switching element electrically connected between the DC power supply circuit and the load,

the power supply device further comprising:

a control circuit configured to output a prescribed control voltage to a control terminal of the switching element so as to turn on the switching element; and

an off-switching circuit configured to reduce a potential of the control terminal of the switching element so as to turn off the switching element, when the ground-fault determining circuit determines the presence of the ground fault,

the prescribed determination reference voltage depending on the prescribed control voltage.

7. The power supply device according to claim 5, wherein the cut-off circuit comprises a full bridge inverter circuit that comprises four switching elements.

8. An illumination device for vehicle, comprising:

the power supply device according to claim 1; and

a light source of emitting light with an output from the power supply device.

9. The power supply device according to claim 2, wherein the prescribed charging voltage is higher than a minimum value of an output voltage from the DC power supply circuit in a state where the ground fault is present at the post-stage of the DC power supply circuit.

10. The power supply device according to claim 2, further comprising:

a resistor for charging, electrically connected across the constant voltage source and the capacitor; and

a resistor for discharging, connected in series with the diode,

the resistor for charging having a resistance value higher than a resistance value of the resistor for discharging.

11. The power supply device according to claim 3, further comprising:

a resistor for charging, electrically connected across the constant voltage source and the capacitor; and

a resistor for discharging, connected in series with the diode,

the resistor for charging having a resistance value higher than a resistance value of the resistor for discharging.

12. The power supply device according to claim 9, further comprising:

a resistor for charging, electrically connected across the constant voltage source and the capacitor; and

a resistor for discharging, connected in series with the diode,

the resistor for charging having a resistance value higher than a resistance value of the resistor for discharging.