Patent ID: 8395874

Claim:
A method for designing a multiphase current supplying circuit comprising: a peak-value suppressor connected to an AC power supply outputting an AC voltage, said peak-value suppressor suppressing a surge voltage superimposed upon said AC voltage; a group of diodes receiving said AC voltage from said AC power supply via said peak-value suppressor to perform full-wave rectification on said AC voltage; a capacitor receiving an output from said group of diodes; an inverter receiving a both-end voltage of said capacitor to output multiphase AC currents; and an inductor connected in series to a circuit configuration of said inverter and said capacitor, wherein a maximum value of said both-end voltage is twice or more a minimum value of said both-end voltage, said method comprising: designing inductance of said inductor such that sum of inductance parasitic in said AC power supply and said inductance of said inductor becomes not less than Ls determined by the following equation: L S = 1 C [ Δ ⁢ ⁢ T cos - 1 ⁢ { 1 - 1 2 ⁢ ( V N - V M V S - V M ) 2 } ] 2 wherein C: capacity of said capacitor, ΔT: pulse width of lightning surge, V N : maximum voltage of both ends of said capacitor, V M : maximum value of said AC voltage (V in ), V s : voltage of lightning surge after clamping.