Ac to dc power conversion method and system

An AC to DC power conversion system for converting AC power from an AC power supply to DC power, the conversion system comprising:

• a plurality of switched-mode DC to DC converters, each DC to DC converter comprising:
• an input comprising a first input terminal for receiving current from said AC power supply, and a second input terminal;
• an output comprising a first output terminal and a second output terminal;
• at least one energy storage component;
• and
• at least one controllable switch for controlling operation of the converter,
• wherein the respective second input terminal of each converter are connected together, and the respective output terminals of each converter are connected in parallel to provide a DC output;
• a controller for controlling operation of said at least one controllable switch of each DC to DC converter;
• means for determining a DC voltage at said DC output;
• means for determining at least one AC voltage signal received from said AC power supply, said at least one AC voltage signal comprising a single-phase voltage signal or a multi-phase voltage signal;
• and
• means for determining AC current at the first input terminal of at least one of said converters,
• wherein for each of said converters said controller is configured to
• generate a reference AC current signal depending on the determined DC voltage and a reference DC voltage, said reference AC current signal being in phase with said single-phase voltage signal or a respective phase of said multi-phase voltage signal, and
• control the operation of said at least one controllable switch to cause the AC current at the first input terminal to match the reference AC current signal.