Power carrier signal coupling circuit and communication system

A communication system, comprising a power carrier signal coupling circuit connected to a three-phase alternating current (AC) power line, wherein the power carrier signal coupling circuit comprises:

• a first power carrier signal coupling channel, comprising a first capacitor;
• a second power carrier signal coupling channel, comprising a second capacitor;
• a signal transceiver;
• and
• a coupling transformer, comprising a primary winding, a first secondary winding and a second secondary winding, wherein a first terminal of the first secondary winding is connected to the signal transceiver, a second terminal of the first secondary winding is connected to a first terminal of the second secondary winding, and a second terminal of the second secondary winding is connected to the signal transceiver, wherein
• a phase of the three-phase AC power line serves as a common channel,
• the first power carrier signal coupling channel is arranged between the common channel and one of two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel,
• the second power carrier signal coupling channel is arranged between the common channel and the other of the two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel, and
• a first terminal of the first capacitor is connected to one of the two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel, a second terminal of the first capacitor is connected to a first terminal of the primary winding, a first terminal of the second capacitor is connected to the other of the two phases of the three-phase AC power line other than the phase of the three-phase AC power line serving as the common channel, a second terminal of the second capacitor is connected to the first terminal of the primary winding, and a second terminal of the primary winding is connected to the common channel.