Direct current power line communication system and direct current power line communication apparatus

A direct current power line communication system comprising:

• a first output terminal that outputs a first direct current voltage;
• a second output terminal that outputs a second direct current voltage of a different value from the first direct current voltage;
• a first direct current voltage line that is connected to the first output terminal, and to which the first direct current voltage is supplied;
• a second direct current voltage line that is connected to the second output terminal, and to which the second direct current voltage is supplied;
• a first direct current power line communication apparatus that is connected to the first direct current voltage line;
• and
• a second direct current power line communication apparatus that is connected to the second direct current voltage line,
• wherein the first direct current power line communication apparatus transmits a first signal that includes a value related to the first direct current voltage to the second direct current power line communication apparatus via the first direct current voltage line and the second direct current voltage line, and
• wherein the first direct current voltage line is connected to the second direct current voltage line by a bypass circuit that transmits the first signal.

A first direct current power line communication apparatus, to which a first direct current voltage is supplied via a first direct current voltage line, the first direct current power line communication apparatus being configured to transmit a first signal to a second direct current power line communication apparatus, to which a second direct current voltage different from the first direct current voltage is supplied via a second direct current voltage line, the first direct current power line communication apparatus comprising:

• a transmitter that is connected to the first direct current voltage line and that, in operation, transmits the first signal to the second direct current power line communication apparatus via the first direct current voltage line and the second direct current voltage line;
• a receiver that, in operation, receives a second signal that includes a value related to the second direct current voltage from the second direct current power line communication apparatus via the first direct current voltage line and the second direct current voltage line;
• and
• a controller that, in operation, controls a signal voltage of the first signal transmitted by the transmitter based on the value related to the second direct current voltage,
• wherein the first direct current voltage line is connected to the second direct current voltage line by a bypass circuit that communicates the first signal and the second signal.