Ground fault detector and power conditioner with input-side ground fault detection
View Patent ↗A power conditioner includes an inverter circuit that converts a DC voltage into an AC voltage, a voltage dividing circuit having one end connected to the positive electrode input terminal and the other end connected to the negative electrode input terminal, and a ground fault detector configured to receive a voltage divided by the voltage dividing circuit as an input voltage signal and to detect an occurrence of a ground fault based on the magnitude of the voltage of the input voltage signal. the ground fault detector emits an AC ground fault detection signal when the input voltage signal includes a first voltage signal having a frequency equal to or higher than a predetermined first frequency and a deviation of the first voltage signal with respect to an AC ground reference potential is equal to or larger than an AC ground fault detection voltage.
1. A power conditioner comprising:
an inverter circuit converting a DC voltage inputted via a positive electrode input terminal and a negative electrode input terminal into an AC voltage;
a voltage dividing circuit having one end connected to the positive electrode input terminal and another end connected to the negative electrode input terminal; and
a ground fault detector receiving a voltage divided by the voltage dividing circuit as an input voltage signal, and detecting an occurrence of a ground fault based on a magnitude of a voltage of the input voltage signal,
wherein
the ground fault detector comprises:
a frequency filter receiving the input voltage signal, passing a first voltage signal having a frequency equal to or higher than a predetermined first frequency, and blocking a signal having a frequency lower than the first frequency;
a first voltage comparison unit generating an AC ground fault detection signal when a deviation of the first voltage signal with respect to a predetermined first reference potential is equal to or greater than a predetermined first voltage; and
a second voltage comparison unit generating a ground fault detection signal when a deviation of the input voltage signal with respect to a predetermined second reference potential is equal to or greater than a predetermined second voltage,
the ground fault detector is configured to detect a DC ground fault in response to only the ground fault detection signal being generated, and detect an AC ground fault in response to both the ground fault detection signal and the AC ground fault detection signal being generated.
2. The power conditioner according to claim 1 , wherein the frequency filter blocks a signal having a frequency higher than a third frequency which is set higher than the first frequency.
3. The power conditioner according to claim 1 , further comprising at least one of an alarm unit outputting an alarm of an AC ground fault in response to the AC ground fault detection signal, and a recording unit recording an AC ground fault occurrence history in response to the AC ground fault detection signal.
4. A ground fault detector comprising:
a frequency filter receiving an input voltage signal, passing a first voltage signal having a frequency equal to or higher than a predetermined first frequency, and blocking a signal having a frequency lower than the first frequency;
a first voltage comparison unit generating an AC ground fault detection signal when a deviation of the first voltage signal with respect to a predetermined first reference potential is equal to or greater than a predetermined first voltage; and
a second voltage comparison unit generating a ground fault detection signal when a deviation of the input voltage signal with respect to a predetermined second reference potential is equal to or greater than a predetermined second voltage,
wherein the ground fault detector is configured to detect a DC ground fault in response to only the ground fault detection signal being generated, and detect an AC ground fault in response to both the ground fault detection signal and the AC ground fault detection signal being generated.