| 摘要 |
PROBLEM TO BE SOLVED: To provide an on-board power system for preventing faults due to a temperature rise in a step-down unit, in the on-board power system for supplying power relating to driving of a steering assist motor.SOLUTION: In an on-board power system 11, a main machine power converter 32 constituting a main machine 30 and a steering power converter 42 constituting a steering assisting device 40 are connected to a main battery 20 in parallel. A steering driving controller 41 for driving the steering power converter 42 is provided with step-down power having been stepped down from the power supply voltage of the main battery 20, by a plurality of step-down units 51, 52, 53. A step-down unit control means 611 determines operation or non-operation of the step-down units 51, 52, 53, such that at least one step-down unit in the plurality of step-down units 51, 52, 53 operates. Thereby, all step-down units are prevented from breaking down at the same time, and a steering assist motor 43 is prevented from becoming unable to continue the driving. A driver obtains steering assist torque surely during steering, and the reliability of the steering assisting device 40 is improved. |
