Communication on a pilot wire

摘要

Systems and methods are disclosed for communicating on a pilot wire between Electric Vehicle Service Equipment (EVSE) and an Electric Vehicle (EV). The EVSE and EV exchange a Pulse Width Modulation (PWM) signal on the pilot wire to control charging operations of the EV. Data communications may also be transmitted on the pilot wire, such as between transmit and receive modems. The modems transmit communication signals either continuously, without regard to the state of the PWM signal, or only when the PWM is in an off-state. If transmitting while PWM is on, the modem needs a large coupling impedance and/or a large signal injection. To transmit only when the PWM is off, the modem may use a blocking diode in the coupling circuit or may synchronize to the pulses in the PWM signal.

主权项

1. A circuit, comprising:
a first modem coupled to a pilot wire system, the pilot wire system coupling electric vehicle service equipment and an electric vehicle and having a pilot wire carrying pulse width modulation (PWM) signals, the first modem transmitting communication signals to a second modem via the pilot wire; and an interface circuit coupling the first modem to the pilot wire, the interface circuit having an impedance that is larger than an effective impedance of the pilot wire system, which corresponds to a combination of an electric vehicle service equipment impedance, an electric vehicle impedance, and a pilot wire cable impedance.