Patent ID: 7923861

Claim:
A method of controlling a hybrid DC power supply system including a first DC power supply device for generating a first output voltage and delivering a first source current (Ibse) flowing from the first DC power supply device or receiving a first sink current (Insk) flowing into the first DC power supply device; a second DC power supply device connected to a load, for delivering a second source current which increases as a second output voltage generated thereby decreases and which decreases as the second output voltage increases; and a voltage increasing/reducing DC/DC converter connected between the first DC power supply device and a junction between the load and the second DC power supply device, for controlling the second output voltage by increasing or reducing duty ratios for driving switching devices thereof, the method of controlling the hybrid DC power supply system including a first operation mode that limits the first source current and a second operation mode that limits the first sink current, the first operation mode comprising the steps of: controlling the hybrid DC power supply system such that a load sink current demanded by the load is the sum of a current converted from the first source current by the DC/DC converter and the second source current; and controlling the second output voltage of the second DC power supply device such that a value of a current flowing from an output point of the first DC power supply device through the DC/DC converter to the junction is less than or equal to a predetermined threshold value such that: when the value of the current flowing through the DC/DC converter is smaller than the threshold value, performing a first mode for controlling the second source current by controlling the second output voltage, and when the value of the current flowing through the DC/DC converter is greater than the threshold value, interrupting the first mode and performing a second mode for reducing the second output voltage and increasing the second source current such that the value of the current flowing through the DC/DC converter is less than or equal to the threshold value.