| 摘要 |
<p>A vehicle power-supply unit has a main power supply (100), a booster circuit (40) which raises the output voltage of the main power supply (100) to supply power to a motor drive circuit (30), a sub power supply which assists supply of electric power to the motor drive circuit (39) by use of the electric power charged and stored by the booster circuit (40), and a power supply control part (62) which controls boosting by the booster circuit (40). The power supply control part (62), on the basis of a booster circuit temperature (Tb) and a sub power supply temperature (Ts), controls the voltage boosted by the booster circuit (40) so as to equalize the balance of the heat generation state of the booster circuit (40) and that of the power supply (50). This reduces the difference between the time when the booster circuit temperature (Tb) reaches an overheat prevention starting temperature and the time when the sub power supply temperature (Ts) reaches the overheat prevention starting temperature, thereby delaying the time of starting overheat prevention, that is, the time of starting motor output restriction as far as possible.</p> |
