Neutral connection detection method for 3/4 -wire active filters

A method of operating a power filter to control characteristics of power from a source to a load, the method comprising:

• receiving measurements of electrical characteristics of source power lines from the power source, wherein the source power lines include a first phase line, a second phase line, a third phase line and a neutral;
• receiving measurements of electrical characteristics of power lines to the load, wherein the load power lines include a first phase line, a second phase line, a third phase line and a neutral;
• providing output current compensation signals at output power lines, wherein the output power lines include a first phase line, a second phase line, a third phase line and a neutral;
• and
• detecting a connection status of a neutral connection to the load, wherein the connection status includes one of connected and disconnected.

A power filter comprising:

• a first input configured to receive measurements of electrical characteristics of source power lines from a power source, wherein the source power lines include a first phase line, a second phase line, a third phase line and a neutral;
• a second input configured to receive measurements of electrical characteristics of load power lines to a load, wherein the load power lines include a first phase line, a second phase line, a third phase line and a neutral;
• an output configured to couple to output power lines to provide output current compensation signals, wherein the output power lines include a first phase line, a second phase line, a third phase line and a neutral;
• a power converter coupled to the power output and configured to receive input power, receive input control signals and provide the output current signals based on the input control signals;
• and
• means for detecting a connection status of a neutral connection to the load, wherein the connection status includes one of connected and disconnected.