Redundant power supply with a switchable, linear voltage regulator

A power system coupled to a load, the power system comprising:

• a relay having a first terminal and a second terminal, the first terminal of the relay being electrically coupled to a secondary power source;
• a voltage regulator circuit having an input terminal and an output terminal, the input terminal of the voltage regulator circuit being electrically coupled to the first terminal of the relay, the output terminal of the voltage regulator circuit being electrically coupled to the second terminal of the relay, and the voltage regulator circuit being capable of switching, based on a control signal received from a controller, between providing a first output voltage and providing a second output voltage, wherein the provided output voltage is applied to the output terminal of the voltage regulator circuit;
• and
• the controller for selecting, via the control signal to the voltage regulator circuit, between the first output voltage and the second output voltage, wherein the selecting is based on the voltage level being provided by a primary power source that is different from the secondary power source, and for controlling the relay;
• wherein whether the load receives power from (i) the primary power source or (ii) the secondary power source is based on the voltage level of the provided output voltage that is applied to the output terminal of the voltage regulator circuit, and
• wherein the power system enables the load to be powered by the primary power source during normal operation, wherein an output voltage from the primary power source is lower than an output voltage from the secondary power source.

A method for selecting the voltage that is presented to a load that is electrically coupled to both a primary power source and a secondary power source, the method comprising:

• opening a relay having a first terminal and a second terminal, the first terminal of the relay being electrically coupled to the secondary power source;
• providing a first output voltage at an output terminal of a voltage regulator circuit that also has an input terminal that is electrically coupled to the first terminal of the relay, the output terminal being electrically coupled to the second terminal of the relay;
• monitoring whether a predetermined conducting current is present at the output terminal of the voltage regulator circuit;
• providing a second output voltage at the output terminal of the voltage regulator circuit based on the predetermined conducting current being detected as having become present, the second output voltage being greater than the first output voltage;
• and closing the relay based on the predetermined conducting current remaining present for a predetermined time interval after being detected as having become present, the predetermined conducting current being measured at least once with respect to the first output voltage being provided to the output terminal during the predetermined time interval;
• wherein the power system enables the load to be powered by the primary power source during normal operation, wherein an output voltage from the primary power source is lower than an output voltage from the secondary power source.