Regenerative braking system and electrically-driven work vehicle using regenerative braking system

A regenerative braking system comprising:

• a first power generator and a second power generator that are connected to an engine;
• a first rectification circuit that is connected to the first power generator and rectifies an output power of the first power generator to output a DC power to a first DC line;
• an inverter that is connected between the first DC line and a travel motor;
• a power consumption device that is connected to the first DC line and is able to consume the power of the first DC line;
• a second rectification circuit that is connected to the second power generator and rectifies an output power of the second power generator to output a DC power to a second DC line;
• an accessory device that is connected to the second DC line;
• a power regeneration device that converts the power of the first DC line to supply a converted power to the second DC line;
• and
• a controller that controls the first power generator, the power consumption device, and the power regeneration device,
• wherein the power regeneration device includes:
• a plurality of power conversion modules configured such that input sections of the plurality of power conversion modules, to which the power of the first DC line is input, are connected in series, and
• a first bypass device group that is connected to each of the input sections of the plurality of power conversion modules, wherein the first bypass device group is able to individually short-circuit a portion of circuits between positive and negative electrode terminals of each of the input sections of the plurality of power conversion modules,
• wherein the controller is configured to:
• control the first power generator, the power consumption device, and the power regeneration device such that a voltage input from the first DC line to the power regeneration device does not exceed a variable upper limit value based on a total voltage withstandable by the plurality of power conversion modules, and
• short-circuit, when some of the plurality of power conversion modules are stopped, one or more of the circuits between the positive and negative electrode terminals of each of the input sections of the plurality of power conversion modules to be stopped and decrease the variable upper limit value based on a total voltage withstandable by the ones of the plurality of power conversion modules not to be stopped.