Uninterruptible power supply device with circuit for degradation judgment of storage battery

• US 7,612,468 B2
• Filed: 02/24/2004
• Issued: 11/03/2009
• Est. Priority Date: 04/04/2003
• Status: Expired due to Fees

• Current Assignee: Sanyo Denki Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Denki Company Limited (Panasonic Holdings Corporation)
• Inventors: Okui, Yoshiaki
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): BERHANU, SAMUEL
• Application Number:
  US10/784,193
• Publication Number:
  US 20040196005A1
• Time in Patent Office: 2,079 Days
• Field of Search: 307/66, 307/64, 307/37, 320/138, 363/26, 363/37
• US Class Current: 307/66
• CPC Class Codes: H02J 7/005 Detection of state of health [SOH]
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 9/062 for AC powered loads

Abstract

There is herein provided an uninterruptible power supply device with a degradation judgment circuit 4 of a storage battery 2 which can perform an exact judgment, continuing the power supply to a load apparatus 8 stably without giving the excessive burden to the storage battery 2. The storage battery 2 is floatingly charged from a rectifier 1 connected with the power source 10. The device has the control circuit 3 for controlling the output voltage of the rectifier 1 and the degradation judgment circuit 4. The output voltage of the rectifier 1 is lowered to below a steady state by the control circuit 3. As a result, the storage battery 2 discharges with the current Idc restricted rather than rated discharge current. And a part of power supply is supplied to the load 8. The degradation judgment circuit 4 judges the degradation of the storage battery based on the discharge voltage Vdc.

Claims

1. An uninterruptible power supply device for supplying power to a load and for floatingly charging a storage battery from a converter connecting to an alternating current power source, and having a degradation judgment circuit for the storage battery, the degradation judgment circuit comprising:

a control circuit for controlling an output voltage of the converter to be lower than a steady state voltage, so as to cause the storage battery to discharge at a more limited current than the rated current of the storage battery, and so as to cause the converter to supply a part of a load current to the load;

a judgment circuit that judges the degradation of the storage battery based on a charging time of the storage battery from a time when the control circuit controls the output voltage of the converter to return to the steady state voltage to a time when the battery is fully charged, the judgment circuit using the charging time to determine whether the storage battery is degraded or normal, a degraded storage battery having a maximum storage capacity that is less than a maximum storage capacity of a new storage battery of the same kind thereof, and

a timer for measuring the charging time of the storage battery from the time when the control circuit controls the output voltage of the converter to return to the steady state voltage to the time when the battery is fully charged.

2. The uninterruptible power supply device according to claim 1, wherein said judgment circuit comprises a timer connecting to a comparator for comparing a charging current of the storage battery with a base current.

3. The uninterruptible power supply device according to claim 1, wherein said converter is a rectifier and said load includes a direct-alternating current inverter and a load apparatus.

4. The uninterruptible power supply device according to claim 1, wherein said converter is a rectifier, the uninterruptible power supply device further comprising a direct-alternating current inverter connected midway between the storage battery and the load.

5. The uninterruptible power supply device according to claim 1, wherein said converter comprises a mutual transducer of direct and alternating current, which connects to the power source in parallel with the load, and which connects the storage battery thereto.

6. The uninterruptible power supply device according to claim 1, wherein said converter comprises a transducer of alternating and direct current which connects to the power source in parallel with the load, and which connects the storage battery and a direct-alternating current inverter.

7. The uninterruptible power supply device according to claim 1, wherein said limited discharge current of the storage battery, caused by controlling the output voltage of the converter to lower below the steady state, is almost constant at what is equivalent to 10-50% of the maximum current of the load.

8. The uninterruptible power supply device according to claim 1, wherein said control circuit connects to a trigger signal source which comprises a memory in which an operational schedule for the degradation judgment is stored, and the converter starts to lower the output voltage at the timing of the trigger signal and the storage battery then starts to discharge.

9. The uninterruptible power supply device according to claim 1, wherein said converter and said control circuit comprise a rectifier for obtaining a direct current from the alternating current power source, and a closing loop for bringing the voltage of the direct current close to an appointed direct current voltage with a pulse duration modulation control for an alternating input voltage of itself.