Power supply protective device, power supply device and switch failure diagnosing method

Patent metadata

Field	Value
Publication number	US-2018024196-A1
Application number	US-201515538147-A
Country	US
Kind code	A1
Filing date	Dec 24, 2015
Priority date	Dec 24, 2014
Publication date	Jan 25, 2018
Grant date	—

Abstract

A power supply protective device, when obtaining an open voltage when a second switch is brought into a closed state and a first switch is brought into an open state during discharging of a power supply, and obtaining a close voltage when the second switch is brought into the closed state and the first switch is brought into the closed state during discharging of the power supply, diagnoses the first switch as having a failure or not on the basis of the open voltage and the close voltage. When executing first a close instruction to the first switch and the second switch, if a voltage difference is less than a first threshold voltage, the first switch is determined to have no open failure, and/or when not less than a second threshold voltage, the second switch is determined to have no open failure.

First claim

1 . A power supply protective device comprising:
a first switch provided between a first terminal to which at least one of a load and a charger is connected and a second terminal to which a power supply is connected; a switching circuit connected in parallel to the first switch and including a second switch and a voltage drop element connected in series to the second switch, the voltage drop element causing a voltage drop of a reference voltage by a current flow; a voltage detection unit which detects at least one voltage of a first voltage as a voltage of the first terminal, a second voltage as a voltage of the second terminal, and a third voltage as a voltage at a point between the second switch and the voltage drop element; and a control unit which gives, to the first switch and the second switch, an open instruction to bring the switch into an open state and a close instruction to bring the switch into a closed state to control switching, and obtains a voltage from the voltage detection unit, wherein the control unit, (1) when obtaining an open voltage in a case where the second switch is brought into the closed state and the first switch is brought into the open state during discharging of the power supply, and obtaining a close voltage in a case where the second switch is brought into the closed state and the first switch is brought into the closed state during discharging of the power supply, diagnoses the first switch as having a failure or not on the basis of the open voltage and the close voltage, (2) when executing first instruction processing of giving the close instruction to the first switch and the second switch, if a voltage difference between the first voltage and the second voltage detected by the voltage detection unit during execution of the first instruction processing is less than a first threshold voltage, determines that the first switch has no open failure, and/or when the third voltage detected by the voltage detection unit during execution of the first instruction processing is not less than a second threshold voltage, determines that the second switch has no open failure.

2 . The power supply protective device according to claim 1 , wherein the voltage drop element is a diode with a current direction from the power supply side toward the load or the charger side as a forward direction, and the reference voltage is a forward direction voltage of the diode.

3 . The power supply protective device according to claim 1 , wherein the voltage detection unit detects a voltage of the first terminal and does not detect a voltage of the second terminal,
the control unit diagnoses the first switch as having a failure or not on the basis of a comparison result obtained by comparing a difference voltage between the close voltage and the open voltage with a third threshold voltage corresponding to the reference voltage.

4 . The power supply protective device according to claim 3 , wherein the control unit diagnoses the first switch as having no failure when a first condition is satisfied that the difference voltage is not less than the third threshold voltage, and diagnoses the first switch as having either an open failure or a closed failure when the first condition is not satisfied.

5 . The power supply protective device according to claim 4 , wherein the control unit obtains a discrimination voltage in a case where the second switch is controlled to be in the open state and the first switch is controlled to be in the closed state during discharging of the power supply, and when the first condition is not satisfied and a second condition is satisfied that the discrimination voltage is not less than the open voltage, diagnoses the first switch as having a closed failure, and when the first condition and the second condition are not satisfied, diagnoses the first switch as having an open failure.

6 . The power supply protective device according to claim 1 , wherein the voltage detection unit detects a first terminal voltage of the first terminal and a second terminal voltage of the second terminal,
the control unit obtains the first terminal voltage and the second terminal voltage in a case where the second switch is controlled to be in the closed state and the first switch is controlled to be in the open state during discharging of the power supply, obtains the open voltage by subtracting the first terminal voltage from the second terminal voltage, obtains the first terminal voltage and the second terminal voltage in a case where the second switch is controlled to be in the closed state and the first switch is controlled to be in the closed state during discharging of the power supply, obtains the close voltage by subtracting the first terminal voltage from the second terminal voltage, and diagnoses the first switch as having a failure or not on the basis of a comparison result obtained by comparing the close voltage and the open voltage, respectively, with a fourth threshold voltage corresponding to the reference voltage.

7 . The power supply protective device according to claim 6 , wherein the control unit diagnoses the first switch as having a closed failure when the open voltage is less than the fourth threshold voltage, and diagnoses the first switch as having an open failure when the close voltage is not less than the fourth threshold voltage.

8 . The power supply protective device according to claim 6 , wherein the control unit diagnoses the second switch as having an open failure when at least either one of the open voltage and the close voltage is not less than a fifth threshold voltage corresponding to the second terminal voltage, the fifth threshold voltage being higher than the reference voltage.

9 . The power supply protective device according to claim 8 , wherein the control unit obtains a cutoff voltage in a case where the second switch is controlled to be in the open state and the first switch is controlled to be in the open state during discharging of the power supply, and when the cutoff voltage is not less than the fifth threshold voltage, diagnoses the second switch as having no failure, and when the cutoff voltage is less than the fifth threshold voltage, diagnoses the second switch as having a closed failure.

10 . The power supply protective device according to claim 9 , wherein the control unit obtains the cutoff voltage at timing when power supply to the load can be cut off.

11 . The power supply protective device according to claim 1 , further comprising a current detection unit which detects discharge current from the power supply,
wherein the control unit obtains a discharge current value from the current detection unit and diagnoses at least the first switch as having a failure or not on condition that the discharge current value becomes less than a defined discharge current value.

12 . The power supply protective device according to claim 1 , wherein the control unit executes second instruction processing of giving the open instruction to the first switch and giving the close instruction to the second switch on condition that the first switch and the second switch have no open failure, and determines that the first switch has no closed failure when a voltage difference between the first voltage and the second voltage detected by the voltage detection unit during execution of the second instruction processing is not less than the first threshold voltage.

13 . The power supply protective device according to claim 12 , wherein the control unit executes third instruction processing of giving the close instruction to the first switch and giving the close instruction to the second switch on condition that the first swit

Assignees

• Gs Yuasa Int Ltd

Inventors

• Imura Masayuki
• Kawauchi Tomohiro
• Mizuta Yoshihiko
• Nakamoto Takeshi

Classifications

• H02J7/663

  using battery or load disconnect circuits (H02J9/002 takes precedence) · CPC title

• H01M2200/00

  Safety devices for primary or secondary batteries · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• G01R31/2607

  Circuits therefor (G01R31/2642 takes precedence) · CPC title

• G01R31/3277 Primary

  of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches · CPC title