Parallel DC-to-AC power inverter system with current sharing technique and method thereof

A parallel DC-to-AC power inverter system having a first DC-to-AC power inverter electrically connected in parallel with a second DC-to-AC power inverter, each of said DC-to-AC power inverters comprising:

• an input port;
• an output port;
• a switching circuit electrically connected between said input port and said output port responsive to inverter control signals to convert a DC voltage at said input port to a first AC output voltage;
• an inductor-capacitor filter electrically connected to said switching circuit for filtering said first AC output voltage to an AC output voltage at output port;
• and
• a controller module for detecting an inductor current at said inductor-capacitor filter to generate an AC inductor current signal, for detecting said AC output voltage at said output port and transforming said AC output voltage to generate a first AC reference current signal, for performing a numerical operation of said first AC reference current signal of said first DC-to-AC power inverter and said first AC reference current signal of said second DC-to-AC power inverter to generate an AC reference current signal, and for generating said inverter control signals responsive to said AC reference current signal and said AC inductor current signal by sensing said inductor current at said inductor-capacitor filter.

A control method for the parallel DC-to-AC power inverter system having a first DC-to-AC power inverter electrically connected in parallel with a second DC-to-AC power inverter, wherein each of said DC-to-AC power inverter comprises an input port, an output port, a switching circuit electrically connected between said input port and said output port responsive to inverter control signals to convert a DC voltage at said input port to a first AC output voltage, an inductor-capacitor filter electrically connected to said switching circuit for filtering said first AC output voltage to a AC output voltage at output port, comprising the steps of:

• detecting an inductor current at said inductor-capacitor filter to generate an AC inductor current signal;
• detecting said AC output voltage at said output terminals and transforming said AC output voltage to generate a first AC reference current signal;
• detecting a load current at output port to generate an AC load current signal;
• generating a second AC reference current signal by adding said first AC reference current signal to said AC load current signal;
• performing a numerical operation of said second AC reference current signal of said first DC-to-AC power inverter and said second AC reference current signal of said second DC-to-AC power inverter to generate an AC reference current signal;
• and
• generating said inverter control signals responsive to said AC reference current signal and said AC inductor current signal by sensing said inductor current at said inductor-capacitor filter.

A control method for the parallel DC-to-AC power inverter system having a first DC-to-AC power inverter electrically connected in parallel with a second DC-to-AC power inverter, wherein each of said DC-to-AC power inverter comprises an input port, an output port, a switching circuit electrically connected between said input port and said output port responsive to inverter control signals to convert a DC voltage at said input port to a first AC output voltage, an inductor-capacitor filter electrically connected to said switching circuit for filtering said first AC output voltage to a AC output voltage at output port, comprising the steps of:

• detecting an inductor current at said inductor-capacitor filter to generate an AC inductor current signal;
• detecting said AC output voltage at said output port and transforming said AC output voltage to generate a first AC reference current signal;
• performing a numerical operation of said first AC reference current signal of said first DC-to-AC power inverter and said first AC reference current signal of said second DC-to-AC power inverter to generate an AC reference current signal;
• and
• generating said inverter control signals responsive to said AC reference current signal and said AC inductor current signal by sensing said inductor current at said inductor-capacitor filter.