Power supply system
A power supply system includes: a first battery; a second battery having the same configuration as the first battery; auxiliary equipment connected to a low-voltage power line connected to an auxiliary battery; a series-parallel switching circuit configured to switching connection of the first and second batteries between series connection and parallel connection by turning on and off a plurality of relays; and a power converter connected to the series-parallel switching circuit and the low-voltage power line. When the first battery and the second battery are to be charged with power from a power generator, the first and second batteries are connected in series and charged when power consumption of the auxiliary equipment is equal to or greater than predetermined power, and the first and second batteries are not connected in series and are charged when the power consumption of the auxiliary equipment is less than the predetermined power.
1 . A power supply system configured to be mounted on a vehicle, the power supply system comprising:
a first battery;
a second battery having the same configuration as the first battery;
an auxiliary battery having a voltage lower than a rated voltage of the first battery;
auxiliary equipment connected to a low-voltage power line connected to the auxiliary battery;
an in-vehicle power generator connected to the low-voltage power line;
a series-parallel switching circuit including a plurality of relays, the series-parallel switching circuit being configured to switch connection of the first battery and the second battery between series connection and parallel connection by turning on and off the relays;
a power converter connected to the series-parallel switching circuit and the low-voltage power line; and
a controller configured to drive and control the relays of the series-parallel switching circuit and to control the power converter,
wherein the controller is configured to, when the first battery and the second battery are to be charged with power from the power generator,
perform series connection charge control when power consumption of the auxiliary equipment is equal to or greater than predetermined power, the series connection charge control being control in which the controller controls the relays and the power converter such that the first battery and the second battery are connected in series and are charged with the power from the power generator, and
perform non-series connection charge control when the power consumption of the auxiliary equipment is less than the predetermined power, the non-series connection charge control being control in which the controller controls the relays and the power converter such that the first battery and the second battery are not connected in series and are charged with the power from the power generator.
2 . The power supply system according to claim 1 , wherein the controller is configured to perform, as the non-series connection charge control, control of alternately performing a first battery charging process and a state-of-charge equalization process, the first battery charging process being a process of charging the first battery by turning on and off the relays such that the first battery is charged with the power from the power generator, and the state-of-charge equalization process being a process of equalizing a state of charge of the first battery and a state of charge of the second battery by charging the second battery with power from the first battery by turning on and off the relays such that the second battery is charged with the power from the first battery.
3 . The power supply system according to claim 2 , wherein the controller is configured to supply the power from the power generator to the auxiliary equipment or the auxiliary battery during the state-of-charge equalization process.
4 . The power supply system according to claim 1 , wherein:
the series-parallel switching circuit further includes
a series connection line configured to connect an anode terminal of the first battery and a cathode terminal of the second battery;
a series connection relay provided on the series connection line;
a cathode bus connected to a cathode terminal of the first battery;
an anode bus connected to an anode terminal of the second battery;
an inverter connected to the cathode bus and the anode bus;
a three-phase alternating current motor configured to be driven by the inverter;
a cathode relay provided on the cathode bus;
an anode relay provided on the anode bus;
a first parallel connection line configured to connect the series connection line at a position closer to the first battery than the series connection relay and the anode bus;
a first parallel connection relay provided on the first parallel connection line;
a second parallel connection line configured to connect the cathode terminal of the second battery and a neutral point of the three-phase alternating current motor; and
a second parallel connection relay and a third parallel connection relay that are provided on the second parallel connection line in order of the second parallel connection relay and the third parallel connection relay from the second battery; and
the power converter is connected via a charging relay to the cathode bus at a position closer to the first battery than the cathode relay and to the anode bus at a position closer to the second battery than the anode relay.