IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0699425
(2007-01-30)
|
등록번호 |
US-7560935
(2009-07-27)
|
우선권정보 |
JP-2006-020063(2006-01-30) |
발명자
/ 주소 |
|
출원인 / 주소 |
|
대리인 / 주소 |
McDermott Will & Emery LLP
|
인용정보 |
피인용 횟수 :
14 인용 특허 :
1 |
초록
▼
There is a ground-fault resistance measurement circuit which measures a ground-fault resistance between a conductive frame body of electrical equipment and a charge section insulated from the frame body. This ground-fault resistance measurement circuit includes: a capacitor which is connected betwe
There is a ground-fault resistance measurement circuit which measures a ground-fault resistance between a conductive frame body of electrical equipment and a charge section insulated from the frame body. This ground-fault resistance measurement circuit includes: a capacitor which is connected between the charge section and the frame body; a switch which opens and closes a connection path between the charge section and the capacitor; a charging unit which charges the capacitor to a predetermined voltage; a voltage measurement section which measures a charging voltage of the capacitor; a discharge control section which connects the capacitor and the charge section after the capacitor is charged, and discharges the capacitor; and a calculation section which calculates a resistance between the charge section and the frame body, based on a change in the charging voltage of the capacitor.
대표청구항
▼
What is claimed is: 1. A ground-fault resistance measurement circuit which measures a resistance between a charge section insulated from a conductive frame body of an electrical apparatus and the frame body, comprising: a capacitor which is connected between the charge section and the frame body; a
What is claimed is: 1. A ground-fault resistance measurement circuit which measures a resistance between a charge section insulated from a conductive frame body of an electrical apparatus and the frame body, comprising: a capacitor which is connected between the charge section and the frame body; a first switch which opens and closes a connection path between the charge section connected to the capacitor and the capacitor; a charging power-source section which outputs a predetermined set voltage for charge; a charging unit which charges the capacitor, using the predetermined set voltage output from the charging power-source section; a voltage measurement section which measures a charging voltage of the capacitor; a discharge control section which closes the first switch after charging the capacitor by the charging unit; and a calculation section which calculates a resistance value between the charge section and the frame body, based on a change in the charging voltage measured by the voltage measurement section after closing the first switch by the discharge control section. 2. The ground-fault resistance measurement circuit according to claim 1, wherein the calculation section calculates a resistance value RL between the charge section and the frame body, based on a value Vta indicative of a charging voltage of the capacitor as measured by the voltage measurement section at the time when the discharge control section closes the first switch and a value Vtb indicative of a charging voltage measured by the voltage measurement section at the time when a predetermined set time tb elapses after closing the first switch. 3. The ground-fault resistance measurement circuit according to claim 2, further comprising: a first resistance having a first resistance value R1 disposed on a path from the capacitor to the charge section via the first switch; and second and third resistances having a second resistance value R2 and a third resistance value R3, respectively, which serve as voltage dividing resistances for dividing a charge voltage of said capacitor, wherein: said voltage measurement section measures, as the charge voltage, a divided voltage divided by the voltage dividing resistances, and said calculation section calculates the resistance value RL based on the electrostatic capacity C1 of the capacitor and from the following expression: RL=τ×(R2+R3 )/{C1×(R2+R3)-τ}-R1, where τ=tb/(log Vta-log Vtb). 4. The ground-fault resistance measurement circuit according to claim 1, wherein the calculation section calculates a resistance value RL between the charge section and the frame body, based on a first charging voltage Vta measured by the voltage measurement section at the time when a predetermined first set time ta elapses after the discharge control section closes the first switch and a second charging voltage Vtb measured by the voltage measurement section at the time when a predetermined second set time tb elapses after a lapse of the predetermined first set time. 5. The ground-fault resistance measurement circuit according to claim 4, further comprising: a first resistance having a first resistance value R1 disposed on a path from the capacitor to the charge section via the first switch; and second and third resistances having a second resistance value R2 and a third resistance value R3, respectively, which serve as voltage dividing resistances for dividing a charge voltage of said capacitor, wherein: said voltage measurement section measures, as the charge voltage, a divided voltage divided by the voltage dividing resistances, and said calculation section calculates the resistance value RL based on the electrostatic capacity C1 of the capacitor and from the following expression: RL=τ×(R2+R3 )/{C1×(R2+R3)-τ}-R1, where τ=(ta-tb)/(log Vta-log Vtb). 6. The ground-fault resistance measurement circuit according to claim 1, further comprising: a clock section which clocks time ta starting from a point of time when the discharge control section closes the first switch until a point of time the charging voltage measured by the voltage measurement section reaches a first predetermined set voltage V1 or below, and a time tb starting from a point of time when the discharge control section closes the first switch until a point of time the charging voltage measured by the voltage measurement section reaches a second predetermined set voltage V2 or below, said second predetermined set voltage V2 being lower than said first predetermined set voltage V1, wherein, the calculation section calculates a resistance value RL between the charge section and the frame body, based on the time clocked by the clock section. 7. The ground-fault resistance measurement circuit according to claim 6, further comprising: a first resistance having a first resistance value R1 disposed on a path from the capacitor to the charge section via the first switch; and second and third resistances having a second resistance value R2 and a third resistance value R3, respectively, which serve as voltage dividing resistances for dividing a charge voltage of said capacitor, wherein: said voltage measurement section measures, as the charge voltage, a divided voltage divided by the voltage dividing resistances, and said calculation section calculates the resistance value RL based on the electrostatic capacity C1 of the capacitor and from the following expression: RL=τ×(R2+R3 )/{C1×(R2+R3)-τ}-R1, where τ=(tb-ta)/(log V1-log V2). 8. The ground-fault resistance measurement circuit according to claim 1, wherein, the charging unit includes a second switch which opens and closes a connection path between the charging power-source section and the capacitor, and the discharge control section closes the second switch so that the charging power-source section charges the capacitor, and thereafter opens the second switch. 9. The ground-fault resistance measurement circuit according to claim 1, wherein a resistance is disposed on a path from the capacitor through the first switch to the charge section. 10. The ground-fault resistance measurement circuit according to claim 1, further comprising: a voltage-division resistance which divides a charging voltage of the capacitor; wherein the voltage measurement section measures a division voltage obtained from the voltage division by the voltage-division resistance. 11. The ground-fault resistance measurement circuit according to claim 1, further comprising: a display section which displays a resistance value calculated by the calculation section. 12. The ground-fault resistance measurement circuit according to claim 1, wherein: the electrical apparatus includes a battery insulated from the frame body; and the charge section is an electrode of the battery. 13. The ground-fault resistance measurement circuit according to claim 12, wherein: the electrical apparatus is an electric automobile; the battery supplies electric power to a mechanical-power motor of the electric automobile; and the frame body is a body of the electric automobile. 14. A ground-fault detection circuit, comprising: the ground-fault resistance measurement circuit according to claim 1; and a decision section which decides that a ground fault is generated if the resistance value calculated by the calculation section is below a predetermined threshold value. 15. The ground-fault detection circuit according to claim 14, further comprising, a notification section which gives notice of a decision result by the decision section.
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