Patent ID: 9557360
Date: 2017-01-31
CPC Classifications: G01R,H02M

Claim:
1. An apparatus for estimating a capacitance of a DC-link capacitor in an inverter having a rectifier unit, the DC-link capacitor, and an inverter unit, the apparatus comprising: a first estimation unit configured to estimate a DC-link voltage using a measured DC-link voltage, an output current of the inverter unit, and an output voltage of the inverter unit to output the estimated DC-link voltage; a calculation unit configured to calculate an evaluation index from the measured DC-link voltage and the estimated DC-link voltage; and a second estimation unit configured to estimate a DC-link capacitance using the evaluation index and an initial DC-link capacitance, wherein the calculation unit comprises: a first band pass filter (BPF) configured to filter out a component corresponding to a second harmonic of the operating frequency of the estimated DC-link voltage; a first detection unit configured to detect a size of ripple voltage which is an output of the first BPF; a second band pass filter (BPF) configured to filter out a component corresponding to a second harmonic of the operating frequency of the measured DC-link voltage; a second detection unit configured to detect a size of ripple voltage which is an output of the second BPF; and a first comparison unit configured to divide the size of ripple voltage which is an output of the first detection unit by the size of ripple voltage which is an output of the second detection unit.