Capacitor capacitance estimation device, control system, and capacitor capacitance estimation method

A control system comprising a motor system, equipment to operate by receiving a supply of motive power from the motor system, and a capacitor capacitance estimation device, wherein

• the motor system includes:
• a power supply;
• a capacitor to smooth DC voltage from the power supply;
• an inverter to receive a supply of the smoothed DC voltage and to generate AC voltage;
• and
• a motor to be driven by receiving a supply of the AC voltage, and
• the capacitor capacitance estimation device includes:
• processing circuitry
• to generate a filter for removing influence of fluctuation based on a load fluctuation cycle that is a cycle of the fluctuation of a load placed on the motor;
• to acquire a section signal of a predetermined period from an input signal that includes a carrier frequency included in the AC voltage as a component, the carrier frequency being in sync with a pulse width modulation (PWM) signal for controlling the inverter;
• to segment the section signal into a plurality of signals and to generate a plurality of pieces of frequency domain data by converting each of the plurality of signals obtained by the segmentation into a plurality of component values in a frequency domain, each of the plurality of signals having predetermined duration;
• to extract a component value of a frequency corresponding to the carrier frequency from the plurality of component values in each of the plurality of pieces of frequency domain data, to use the extracted component value as a value at time corresponding to the corresponding one of the extracted signals, and to generate time-series data representing a plurality of the extracted component values in a time series;
• to generate processed time-series data by applying the filter to the time-series data;
• and
• to estimate the capacitance of the capacitor from the processed time-series data.

A capacitor capacitance estimation method of estimating capacitance of a capacitor in an equipment system including a power supply, the capacitor to smooth DC voltage from the power supply, an inverter to receive a supply of the smoothed DC voltage and to generate AC voltage, and electric equipment to operate by receiving a supply of the AC voltage, comprising:

• generating a filter for removing influence of fluctuation based on a load fluctuation cycle that is a cycle of the fluctuation of a load placed on the electric equipment;
• acquiring a section signal of a predetermined period from an input signal that includes a carrier frequency included in the AC voltage as a component, the carrier frequency being in sync with a pulse width modulation (PWM) signal for controlling the inverter;
• segmenting the section signal into a plurality of signals and generating a plurality of pieces of frequency domain data by converting each of the plurality of signals obtained by the segmentation into a plurality of component values in a frequency domain, each of the plurality of signals having predetermined duration;
• extracting a component value of a frequency corresponding to the carrier frequency from the plurality of component values in each of the plurality of pieces of frequency domain data, using the extracted component value as a value at time corresponding to the corresponding one of the extracted signals, and generating time-series data representing a plurality of the extracted component values in a time series;
• generating processed time-series data by applying the filter to the time-series data;
• and
• estimating the capacitance of the capacitor from the processed time-series data.