초록 ▼

A power inverter for use in the system interconnection of a direct-current supply with a commercial alternating-current supply includes an inverter circuit and a filter circuit. Feedback signals affecting the frequency of an output to be produced by the inverter circuit are taken from the filter cir

A power inverter for use in the system interconnection of a direct-current supply with a commercial alternating-current supply includes an inverter circuit and a filter circuit. Feedback signals affecting the frequency of an output to be produced by the inverter circuit are taken from the filter circuit having frequency response characteristics such that the phase angle is reduced to 0°at three frequencies consisting of a higher frequency, lower frequency and commercial frequency, the last of which lies halfway between the first and second. Under the normal condition, the frequency of the output produced by the inverter circuit is equal to the commercial frequency. In the event of a power failure or power cut in the commercial alternating-current supply system, deviation from the commercial frequency is caused by the characteristics of the filter circuit.

대표청구항 ▼

A power inverter for use in system interconnection, comprising: an inverter circuit changing an output power of a direct-current supply to alternating-current power to be delivered to a load connected to a commercial alternating-current supply system; means for separating a fundamental frequency com

A power inverter for use in system interconnection, comprising: an inverter circuit changing an output power of a direct-current supply to alternating-current power to be delivered to a load connected to a commercial alternating-current supply system; means for separating a fundamental frequency component from voltage at a junction point between said inverter circuit and the commercial alternating-current supply system and for providing an output signal having the fundamental frequency, said means having frequency response characteristics such that a phase angle between the voltage and the output signal is reduced to 0°when the fundamental frequency component is at a first frequency which is equal to a commercial frequency, when the fundamental frequency component is at a second frequency which is higher than the commercial frequency, and when the fundamental frequency component is at a third frequency which is lower than the commercial frequency; a drive circuit capable of driving said inverter circuit into outputting a current in phase with the output signal taken from said means; and a protection device cutting a connection between said inverter circuit and the commercial alternating-current supply system when a frequency of the voltage at the junction point changes.