Method and apparatus for adaptive feedforward correction of output current ripple in an on-board charging system

A charging system, comprising:

• an AC-DC converter having input terminals for connecting to AC mains;
• a DC-link having a terminal connected to an output terminal of the AC-DC converter, the DC-link comprising at least one capacitor;
• a DC-DC converter having an input terminal coupled to the output terminal of the AC-DC converter, a control input terminal, and an output terminal for coupling to a load to be charged, the DC-DC converter including drive circuitry for controlling the DC-DC converter;
• and
• a controller having at least one feedforward input terminal coupled to the DC-link for receiving a signal corresponding to a voltage across the DC-link, at least one feedback input terminal for receiving at least one signal corresponding to an output current provided by the DC-DC converter at the output terminal thereof, and at least one output terminal coupled to the control input terminal of the DC-DC converter, the controller generating a control signal at the at least one output terminal which controls the drive circuitry of the DC-DC converter,
• wherein:
• the control signal generated by the controller is based upon a positive half cycle and a negative half cycle of ripple voltage at the DC-link, and an amplitude of a ripple current at the output terminal of the DC-DC converter during at least one of the positive half cycle or the negative half cycle;
• the controller determines a plurality of error values associated with the ripple current at the output terminal of the DC-DC converter during at least one of the positive half cycle or the negative half cycle in each of a plurality of cycles of the ripple voltage at the DC-link, and adjusts a feedforward coefficient based upon the plurality of error values, the control signal generated by the controller is based upon the adjusted feedforward coefficient, each error value associated with the ripple current at the output terminal of the DC-DC converter is based upon an instantaneous current at the output terminal of the DC-DC converter and a setpoint current value;
• the controller adjusts the control signal based on both the positive and negative half cycles of the ripple voltage at the DC-link, for each cycle of the ripple voltage at the DC-link in a plurality of cycles thereof,
• during the positive half cycle of each of the plurality of cycles, the error value associated with the current ripple at the output terminal of the DC-DC converter comprises the instantaneous value of the ripple current at the output terminal of the DC-DC converter less the setpoint current value, and
• during the negative half cycle of each of the plurality of cycles, the error value associated with the current ripple at the output terminal of the DC-DC converter comprises the setpoint current value less the instantaneous value of the ripple current at the output terminal of the DC-DC converter.