Converter and power conversion device having an imbalance detection unit

摘要

A converter includes a converter circuit that converts the AC voltages supplied from the Δ-connection and the Y-connection, which are two systems of a 12-phase rectifier transformer, to a DC voltage; a current detector that detects the current in a DC bus output from the converter circuit; and an imbalance detection unit that detects the occurrence of an imbalance between the current output from the Δ-connection and the current output from the Y-connection, the currents being detected by the current detector. The converter can detect an imbalance that occurs between the current flowing in the diode bridge on the Δ-connection side and the current flowing in the diode bridge on the Y-connection side.

主权项

1. A converter comprising:
a converter circuit that converts an AC voltage supplied from a Δ-connection and a Y-connection, which are two systems of a 12-phase rectifier transformer, to a DC voltage; a current detector that detects a current in a DC bus output from the converter circuit; and an imbalance detection unit that detects occurrence of imbalance between a current output from the Δ-connection and detected by the current detector and a current output from the Y-connection and detected by the current detector, wherein the imbalance detection unit includes a DC-current detection unit that detects a DC current on the basis of a detection value detected by the current detector, a peak-value detection unit that detects a peak value of the DC current, a bottom-value detection unit that detects a bottom value of the DC current, a difference detection unit that detects a difference between the peak value and the bottom value, a setting unit that sets a threshold for a difference between the peak value and the bottom value of the DC current, a comparison unit that compares a threshold set by the setting unit with the difference detected by the difference detection unit, and a signal output unit that outputs an alarm signal when a result of a comparison made by the comparison unit is detected by the difference detection unit as a difference that exceeds the threshold set by the setting unit.