Input redundant power supply with zero current switching

A method of controlling an input redundant power supply circuit including a power converter electrically coupled between a primary power source and a secondary power source and a load via a step-up converter, the method comprising:

• detecting that a relay switch of the primary power source that supplies power to the load via an electrically connected high capacity capacitor is closed and a relay switch of the secondary power source is open;
• enabling the power converter by the primary power source;
• determining that a failure has occurred with the primary power source;
• enabling the step-up converter before the relay switch of the primary power source is open;
• maintaining by the enabled step-up converter a voltage across the high capacity capacitor higher than a voltage of the secondary power source before the relay switch of the primary power source is open and the relay switch of the secondary power source is closed;
• disabling the power converter provided between the primary and secondary power sources and the load before the relay switch of the primary power source is open;
• providing power to the load from the secondary power source;
• and
• disabling the enabled step-up converter after the relay switch of the secondary power source is closed.

A method of controlling an input redundant power supply circuit including a power converter electrically coupled between a primary power source and a secondary power source and a load via a step-up converter, the method comprising:

• detecting that a relay switch of the primary power source that supplies power to the load via an electrically connected high capacity capacitor is closed and a relay switch of the secondary power source is open;
• enabling the power converter by the primary power source;
• determining that a failure has occurred with the primary power source;
• disconnecting an additional power source supplied with power from the primary power source and disconnecting the high capacity capacitor from the primary power source;
• enabling the step-up converter before the relay switch of the primary power source is open;
• maintaining by the enabled step-up converter a voltage across the high capacity capacitor higher than a voltage of the secondary power source before the relay switch of the primary power source is open and the relay switch of the secondary power source is closed;
• disabling the power converter provided between the primary and secondary power sources and the load before the relay switch of the primary power source is open;
• providing power to the load from the secondary power source;
• disabling the enabled step-up converter after the relay switch of the secondary power source is closed;
• and
• limiting charging of the additional power source to prevent a surge current on the relay switches when connecting the additional power source to the high capacity capacitor after the relay switch of the primary power source is open and the relay switch of the secondary power source is closed.