Power supply apparatus and power supply switching method

1. A power supply apparatus comprising:

a plurality of power storage modules that are connected in parallel; and

a backup power storage module that is connected in parallel with the plurality of power storage modules,

wherein, when charging or discharging of at least one of the power storage modules is disabled, charging of the other power storage modules is inhibited, and

wherein discharging of the backup power storage module is permitted, states of charge of the backup power storage module and the other power storage modules are detected, and charging of the backup power storage module and the other power storage modules is permitted in accordance with the detected states of charge.

2. The power supply apparatus according to claim 1 ,

wherein the states of charge of the backup power storage module and the other power storage modules are detected from respective discharge currents.

3. The power supply apparatus according to claim 2 ,

wherein charging of the backup power storage module and the other power storage modules is permitted after the respective discharge currents become substantially equal.

4. The power supply apparatus according to claim 3 ,

wherein the charging is permitted after a difference between the respective discharge currents becomes ±20%.

5. The power supply apparatus according to claim 1 ,

wherein the states of charge of the backup power storage module and the other power storage modules are detected from respective output voltages.

6. The power supply apparatus according to claim 1 ,

wherein the plurality of power storage modules each include a battery unit, a charging switch, a discharging switch, and a control unit that controls the charging switch and the discharging switch,

wherein the backup power storage module includes a battery unit, a charging switch, a discharging switch, and a control unit that controls the charging switch and the discharging switch,

wherein, when charging or discharging of at least one of the power storage modules is disabled, the charging switches of the other power storage modules and the backup power storage module are turned off, and

wherein, after discharge currents of the other power storage modules and the backup power storage module become substantially equal, the charging switches of the backup power storage module and the other power storage modules are turned on.

7. The power supply apparatus according to claim 6 ,

wherein the charging switches are turned on after a difference between the discharge currents of the other power storage modules and the backup power storage module becomes ±20%.

8. The power supply apparatus according to claim 6 , further comprising:

a controller that communicates with the control units of the plurality of power storage modules and the control unit of the backup power storage module,

wherein the controller controls the charging switches and the discharging switches through the control units of the plurality of power storage modules and the control unit of the backup power storage module.

9. The power supply apparatus according to claim 6 ,

wherein both the charging switch and the discharging switch of the backup power storage module are off under normal conditions.

10. The power supply apparatus according to claim 1 ,

wherein the number of the plurality of power storage modules is N (N=2, 3, 4, . . . ), and

wherein the number of the backup power storage modules is one.

11. The power supply apparatus according to claim 1 ,

wherein the number of the plurality of power storage modules is N (N=2, 3, 4, . . . ),

wherein the number of the backup power storage modules is two or more, and

wherein one of the backup power storage modules is selectively used.

12. A power supply switching method comprising:

separating, from a system, at least one of a plurality of power storage modules that are connected in parallel;

adding a backup power storage module such that the backup power storage module is connected in parallel with the other power storage modules;

inhibiting charging of the other power storage modules and the backup power storage module when adding the backup power storage module;

detecting respective states of charge of the other power storage modules and the backup power storage module; and

permitting charging of the other power storage modules and the backup power storage module in accordance with the detected states of charge.

13. The power supply switching method according to claim 12 ,

wherein the plurality of power storage modules each include a battery unit, a charging switch, a discharging switch, and a control unit that controls the charging switch and the discharging switch,

wherein the backup power storage module includes a battery unit, a charging switch, a discharging switch, and a control unit that controls the charging switch and the discharging switch, and

wherein the power supply switching method includes,

with the control units, controlling permission or inhibition of charging by turning on or off the charging switches,

with the control units, controlling permission or inhibition of discharging by turning on or off the discharging switches,

when separating at least one of the power storage modules from the system, turning off the charging switches of the other power storage modules and the backup power storage module, and

after discharge currents of the other power storage modules and the backup power storage module become substantially equal, turning on the charging switches of the backup power storage module and the other power storage modules.