Process for the pulse width modulation voltage converters and inverter

In the calculation of a three-phase alternating output current Iu, Iv, Iw of an inverter based on the input DC current Idc, it is difficult to detect the DC current Idc when the pulse width of the line-to-line voltage is small, whereby the pulse width of the DC current Idc is small , The frequency Fc of the carrier wave C is lowered for a phase whose line-to-line voltage is high, whereby the pulse width of the DC current Idc is larger. As a result, the current can be detected.