Power regeneration system of work vehicle

A power regeneration system of a work vehicle, comprising:

• a first generator and a second generator that are driven by an engine;
• a first electric circuit for supplying electric power generated at the first generator, to traveling motors connected to drive wheels of the work vehicle;
• a second electric circuit for supplying electric power generated at the second generator, to an auxiliary device of the work vehicle;
• a voltage step down converter that is connected at a high voltage side to the first electric circuit and connected at a low voltage side to the second electric circuit, the voltage step down converter providing electric power from the first electric circuit to the second electric circuit;
• and
• a controller that determines whether a travel mode of the work vehicle is a powering mode or a regeneration mode in order to control driving of the voltage step down converter, the powering mode corresponding to a normal traveling state, the regeneration mode corresponding to a traveling state where regenerative power is generated,
• wherein, if the travel mode of the work vehicle is the regeneration mode, the controller controls driving of the voltage step down converter to provide the regenerative power from the first electric circuit through the voltage step down converter to the second electric circuit, in order to drive the auxiliary device with the regenerative power,
• wherein the first electric circuit includes a first rectifier circuit that is connected to the first generator, first power conversion devices that are connected at input sides to the first rectifier circuit and connected at output sides to the traveling motors, a resistor and a chopper that are connected to the input sides of the first power conversion devices, and a first voltage detector that detects a voltage in the first electric circuit,
• wherein the second electric circuit includes, at least, a second rectifier circuit that is connected to the second generator, a second power conversion device that is connected at an input side to the second rectifier circuit and connected at an output side to the auxiliary device of the work vehicle, and a second voltage detector that detects a voltage in the second electric circuit, and
• wherein, if the travel mode is the powering mode and a first voltage value detected at the first voltage detector is greater than a first threshold value, and if the travel mode is the regeneration mode and the first voltage value is greater than a second threshold value, the controller drives the voltage step down converter to provide electric power from the first electric circuit to the second electric circuit.