Patent ID: 9075089
Filing Date: 2015-07-07
Classification: G01R,H02M

Abstract:
1. A method of measuring a link voltage, performed in a direct AC-AC power converter circuit including: a DC link; a current source converter having three input terminals for receiving three-phase AC voltages by phase, and commutating current supplied from said input terminals at a cycle which is divided into a first period and a second period to apply a link voltage which is a DC voltage to said DC link; and a voltage source inverter for performing switching on said link voltage with a switching pattern based on pulse width modulation to output multiphase alternating current, said first period being a period in which said DC link is supplied with current flowing into a first pair out of said three input terminals, to which a voltage of maximum phase and a voltage of minimum phase among said three-phase AC voltages are applied, and said second period being a period in which said DC link is supplied with current flowing into a second pair out of said three input terminals, to which a voltage of intermediate phase and said voltage of said minimum phase among said three-phase AC voltages are applied, said method comprising the steps of: (a) measuring a first measured value which is said link voltage measured at a midpoint of a first section in which only a first said switching pattern is adopted for the longest time in said first period; (b) measuring a second measured value which is said link voltage measured at a midpoint of a second section in which only a single said switching pattern is adopted for a time as long as said first section or for the second longest time next to said first section in said first period; and (c) obtaining a representative value of said link voltage in one said cycle including said first period by interpolation of said first measured value and said second measured value.