Apparatus and method for controlling circulating current in an inverter system

A control system for a power conversion system comprising:

• a voltage controller responsive to three-phase voltage signals to generate corresponding voltage modulation signals;
• current sharing channels responsive to a plurality of circulating currents from a plurality of inductive components, wherein the inductive components are associated with respective phases of the three-phase voltage signals, wherein the current sharing channels generate current sharing modulation signals respectively associated with each phase of the three-phase voltage signals using the plurality of circulating currents from the plurality of inductive components;
• and
• a plurality of combiner circuits, wherein each combiner circuit is associated with a phase of the three-phase voltage signals, and wherein the combiner circuits combine the voltage modulation signals and the current sharing modulation signals respectively associated with each phase of the three-phase voltage signals to generate PWM control signals.

A power conversion system configured to supply multiphase power, the multiphase power having a phase voltage respectively associated with each phase of the multiphase power, the power conversion system comprising:

• a PWM drive circuit;
• a plurality of inverters having inputs coupled to the PWM drive circuit;
• a plurality of inductive components coupled to PWM voltage outputs of the plurality of inverters;
• a plurality of power supply output terminals coupled to the outputs of the plurality of the inductive components;
• a plurality of current sensors coupled to the plurality of inductive components;
• a voltage controller coupled to the plurality of inductive components;
• a current sharing system coupled to the plurality of current sensors;
• a combiner circuit coupled to outputs of the voltage controller and to outputs of the current sharing system;
• and
• a drive circuit coupled to the combiner circuit.

A method for controlling a multiphase power conversion system comprising:

• generating voltage modulation signals in response to each phase voltage of the multiphase power;
• detecting circulating currents flowing through a plurality of inter-cell transformers, each of which are associated with a respective phase voltage;
• applying a controller to the detected circulating currents pursuant to generating current sharing modulation signals corresponding to the circulating currents;
• and
• combining voltage modulation signals and current sharing modulation signals to generate PWM control signals.