Methods and systems for reducing conducted electromagnetic interference

A method for assembling a motor controller, wherein the motor controller is coupled to a power line comprising at least a first alternating current (AC) line output and a second AC line output, said method comprising:

• providing an EMI filter having at least a first EMI filter input terminal, a second EMI filter input terminal, a first EMI filter output terminal, and a second EMI filter output terminal, the first EMI filter input terminal configured to be coupled to the first AC line output and the second EMI filter input terminal configured to be coupled to the second AC line output;
• coupling a rectifier portion to the EMI filter, the rectifier portion including a first rectifier input terminal coupled to the first EMI filter output terminal and a second rectifier input terminal coupled to the second EMI filter output terminal;
• coupling at least two filter capacitors in series after the rectifier portion;
• and
• coupling a first end of a power factor correction (PFC) choke to one of the first and second EMI filter output terminals and to one of the first and second rectifier input terminals, and a second end of the PFC choke to a common node between the at least two series-coupled filter capacitors.

A motor control system for electromagnetic interference (EMI) reduction provided by a power line to an electric motor, the power line comprising at least a first alternating current (AC) line output and a second AC line output, said motor control system comprising:

• a motor controller;
• and
• a drive circuit comprising:
• an EMI filter having at least a first EMI filter input terminal, a second EMI filter input terminal, a first EMI filter output terminal, and a second EMI filter output terminal, said first EMI filter input terminal configured to be coupled to the first AC line output and said second EMI filter input terminal configured to be coupled to the second AC line output;
• a rectifier portion comprising a first rectifier input terminal coupled to said first EMI filter output terminal and a second rectifier input terminal coupled to said second EMI filter output terminal;
• at least two series-coupled filter capacitors positioned after said rectifier portion;
• and
• a power factor correction (PFC) choke comprising a first end and a second end, said first end coupled to one of said first and second EMI filter output terminals and to one of said first and second rectifier input terminals, said second end coupled between said at least two series-coupled filter capacitors.