| 摘要 |
PROBLEM TO BE SOLVED: To detect DC earth without stopping the operation of an inverter even in a portion where a DC ground voltage is zero or near zero in a DC power supply such as a solar battery. SOLUTION: A power conversion system has a DC power supply, where DC ground voltage is substantially fixed, having a designated ground stray capacitance and outputting DC power, with a power conversion means converting the DC power output from the DC power supply to AC power by switching. The phase of DC ground voltage produced in the DC power supply by switching is detected (ST102), the phase of AC earth current flowing through the ground stray capacitance and the earth resistance of the DC power supply is detected (ST03), and a difference between two detected phases is compared with a designated threshold, thereby determining DC earth of the DC power supply (ST08).
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