US 12,334,770 B2
Uninterruptible power supply
Jun Matsumoto, Chuo-ku (JP)
Assigned to TMEIC Corporation, Chuo-ku (JP)
Appl. No. 18/041,091
Filed by TOSHIBA MITSUBISHI-ELECTRIC INDUSTRIAL SYSTEMS CORPORATION, Chuo-ku (JP)
PCT Filed Jun. 16, 2021, PCT No. PCT/JP2021/022819
§ 371(c)(1), (2) Date Feb. 9, 2023,
PCT Pub. No. WO2022/264303, PCT Pub. Date Dec. 22, 2022.
Prior Publication US 2023/0307942 A1, Sep. 28, 2023
Int. Cl. H02J 9/06 (2006.01); H02J 3/32 (2006.01)
CPC H02J 9/06 (2013.01) [H02J 3/32 (2013.01)] 6 Claims
OG exemplary drawing
 
1. An uninterruptible power supply comprising:
a power conversion device connected between a power system and a load;
a frequency detector that detects a system frequency, the system frequency being a frequency of an AC voltage on the power system; and
a controller that controls the power conversion device, wherein
the power conversion device includes:
a converter that converts AC power supplied from the power system into DC power;
an inverter that converts DC power supplied from the converter or a power storage device into AC power and supplies the AC power to the load; and
a bidirectional chopper that selectively performs a charging operation and a discharging operation, the charging operation being an operation in which a part of the DC power generated by the converter is stored in the power storage device, the discharging operation being an operation in which the DC power of the power storage device is supplied to the inverter,
the controller includes a control circuit that controls the bidirectional chopper to perform the discharging operation when a power failure of the power system occurs, and controls the bidirectional chopper based on the detected system frequency when the power system is normal, wherein
(1) when the power system is normal and when an amount of power storage in the power storage device is less than a threshold value, the control circuit controls the bidirectional chopper to control the charging operation until the amount of the power storage reaches the threshold value and then stops the charging operation,
(2) when the power system is normal, when the amount of power storage is equal to or more than the threshold value and when the system frequency increases, the control circuit controls the bidirectional chopper to perform the charging operation, and
(3) when the power system is normal, when the amount of power storage is equal to or more than the threshold value and when the system frequency decreases, the control circuit controls the bidirectional chopper to perform the discharging operation.