Tmeic Corporation

Toshiba Mitsubishi-electric Industrial Systems Corporation

Masamichi Kano

Hidenobu Tajima

Yousuke Hayashi

Kazunori Sanada

Daiki Mori

A phase synchronization control circuit includes: a phase difference detector that detects a phase difference between AC voltage and an AC signal, a frequency control circuitry that generates a first frequency control value to eliminate the phase difference, a frequency limiter that limits the first frequency control value to fall within a variable limit range to generate a second frequency control value, a limiter control circuitry that sets the variable limit range based on the phase difference and reduces the variable limit range in width in response to the phase difference decreasing, and an oscillator that generates the AC signal with a frequency of a value corresponding to the second frequency control value. This can suppress overshooting of the AC signal in frequency to be small.

Phase synchronization control circuit and power conversion device using the same

In the present uninterruptible power supply apparatus, in a switching period in which a bypass power feed mode is switched to an inverter power feed mode, a semiconductor switch is turned on, a first electromagnetic contactor is turned off, a second electromagnetic contactor is turned on and, in this state, an inverter is activated to start a lap power feed mode, and the semiconductor switch is turned off to end the lap power feed mode. Accordingly, the lap power feed mode can be completed in a short time to reduce an increase of a terminal-to-terminal voltage of a capacitor and thereby prevent the terminal-to-terminal voltage of the capacitor from exceeding an upper limit voltage.

Uninterruptible power supply apparatus

An uninterruptible power supply apparatus includes: an electromagnetic contactor including a first terminal that receives a first AC voltage supplied from an AC power supply and a second terminal connected to an AC node; a capacitor that is connected to a DC line and stores DC power; a converter that transmits and receives electric power between the AC node and the DC line; and a controller. In an activation mode, the controller turns on the electromagnetic contactor after controlling the converter such that a frequency and a phase of a second AC voltage supplied from the converter to the AC node match a frequency and a phase of the first AC voltage. In a normal operation mode after the activation mode, the controller controls the converter such that a DC voltage of the DC node attains to a reference voltage.

Power converter

In an uninterruptible power supply apparatus, AC current, which includes a feedback component having a value corresponding to deviation between terminal-to-terminal voltage of a capacitor and reference voltage, and a feed forward component obtained by multiplying load current by a gain, is passed into a converter such that the terminal-to-terminal voltage of the capacitor becomes the reference voltage. The gain is set to a first gain in an inverter power feed mode and a bypass power feed mode, and the gain is set to a second gain smaller than the first gain in a switching period of switching between the inverter power feed mode and the bypass power feed mode, to prevent the terminal-to-terminal voltage of the capacitor from exceeding an upper limit voltage in a lap power feed mode.

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Chuo-ku, Japan

Masamichi Kano