Apparatus for diagnosing DC link capacitor of inverter

摘要

The present disclosure relates to an apparatus for diagnosing a DC link capacitor. A DC voltage provided from a power supplier to a motor is controlled to have a predetermined level (or magnitude). When a voltage of the DC link reaches a predetermined voltage, the ratio of change of capacitance values of the DC link capacitor is estimated, by considering power consumption of a resistor of the motor (i.e., power consumption of a load), power consumption of the power supplier and a switching loss of an inverter part, and a deteriorated level of the DC link capacitor is diagnosed using the estimated ratio.

主权项

1. A diagnosis apparatus for diagnosing deterioration of a DC link capacitor of an inverter having the DC link capacitor and an inverter part comprising a plurality of switching devices generating three phase AC voltages to a load connected to the diagnosis apparatus, the diagnosis apparatus comprising:
a current detector configured to detect a current supplied to a motor in the inverter part; a switching mode power supplier (SMPS) configured to supply a DC voltage and to be coupled to the DC link capacitor; and a controller configured to control the DC voltage supplied from the SMPS to the motor to have a predetermined level, the controller being arranged to estimate the change of a ratio of a deteriorated capacitance to an initial capacitance of the DC link capacitor by considering power consumption of the motor, power consumption of the SMPS and a switching loss of the inverter part, wherein the estimation includes, in response to the voltage of the DC link capacitor reaching a predetermined final level: determining a first factor, k_old, based on a ratio of the power consumption of the SMPS and switching loss to power consumption of the motor using the deteriorated capacitance of the DC link capacitor, determining a second factor, k_int, based on a ratio of the power consumption of the SMPS and switching loss to power consumption of the motor using the initial capacitance of the DC capacitor, determining a first product by multiplying the first factor, k_old, with a rate of the power consumption of the motor using the deteriorated capacitance of the DC link capacitor, determining a second product by multiplying the second factor, k_int, with the rate of the power consumption of the motor using the initial capacitance of the DC link capacitor, determining a quotient of the first and second products to diagnose the DC link capacitor, and controlling the plurality of switching devices in a preset manner such that the controller detects the capacitance of the DC link capacitor.