Management device and power supply system
View Patent ↗Provided is management device that manages a plurality of power storage modules connected in parallel to load with respective switches. Management device has a first state where some of switches connected to some of the plurality of power storage modules are turned on and other of switches connected to remaining power storage modules are turned off, and includes determination unit that does not permit turning on at least one of the other of switches connected to other power storage modules and turned off in the first state when an upper limit value of current or power that is allowed to be discharged to load from the entire plurality of power storage modules is lower than a first threshold based on a maximum value of current or power required by load in a state where the at least one of the other of switches is turned on.
1 . A management device that manages a plurality of power storage modules each connected in parallel to a load via a corresponding switch and includes a first state in which a switch corresponding to each of one or more power storage modules of the plurality of power storage modules is turned on and a switch corresponding to each of one or more remaining power storage modules of the plurality of power storage modules is turned off, the management device comprising:
an acquisition unit configured to acquire at least a state of charge for each of the plurality of power storage modules;
a calculator configured to estimate an upper limit value of current or power allowed to be discharged from all of the plurality of power storage modules, based on SOC-discharge upper limit characteristics that define a relationship between the state of charge of each of the plurality of power storage modules and an upper limit value of current or power allowed to be discharged from a corresponding one of the plurality of power storage modules,
wherein the SOC-discharge upper limit characteristics show that the upper limit value of current or power allowed to be discharged from each of the plurality of power storage modules decreases as the state of charge of the corresponding one of the plurality of power storage modules decreases; and
a determination unit configured to not permit turning on the switch corresponding to at least one of the one or more remaining power storage modules and turned off in the first state when;
the switch corresponding to each of the one or more power storage modules of the plurality of power storage modules is turned on, and
the upper limit value of current or power that is allowed to be discharged to the load from all of the plurality of power storage modules in a state where the switch corresponding to the at least one of the one or more remaining power storage module is turned on is lower than a first threshold based on a maximum value of current or power required by the load,
wherein
the acquisition unit acquires an open circuit voltage of a power storage module of a connection candidate among the one or more remaining power storage modules,
the calculator derives a first upper limit value of current or power allowed to be discharged from each of the plurality of power storage modules connected to the load based on the SOC-discharge upper limit characteristics and the state of charge of each of the plurality of power storage modules connected to the load, and estimates a closed circuit voltage of each of the plurality of power storage modules connected to the load when discharging is performed from the plurality of power storage modules connected to the load at the first upper limit value,
the determination unit permits turning on the switch connected to the power storage module of the connection candidate among the one or more remaining power storage modules, when the open circuit voltage of the power storage module of the connection candidate among the one or more remaining power storage modules is larger than or equal to the closed circuit voltage of each of the plurality of power storage modules connected to the load,
the calculator estimates, when the open circuit voltage of the power storage module of the connection candidate among the one or more remaining power storage modules is lower than or equal to the closed circuit voltage of each of the plurality of power storage modules connected to the load, a current value flowing through the power storage module of the connection candidate among the one or more remaining power storage modules when the closed circuit voltage of the power storage module of the connection candidate corresponds to the closed circuit voltage of each of the plurality of power storage modules connected to the load when discharging is performed at the first upper limit value, and
the determination unit permits turning on the switch connected to the power storage module of the connection candidate among the one or more remaining power storage modules when a second upper limit value of current or power allowed to be discharged from all of the plurality of power storage modules is larger than or equal to the first threshold, the second upper limit value being acquired by subtracting the current value from the first upper limit value.
2 . The management device according to claim 1 , wherein
the calculator estimates a third upper limit value of current or power allowed to be discharged from all of the plurality of power storage modules when the open circuit voltage of each of the plurality of power storage modules connected to the load corresponds to the open circuit voltage of the power storage module of the connection candidate after the switch connected to the power storage module of the connection candidate among the one or more remaining power storage modules is turned on, the third upper limit value being estimated based on:
the SOC-discharge upper limit characteristics,
the state of charge corresponding to the open circuit voltage of each of the plurality of power storage modules connected to the load, and
the state of charge corresponding to the open circuit voltage of the power storage module of the connection candidate, and
the determination unit does not permit turning on the switch connected to the power storage module of the connection candidate among the one or more remaining power storage modules when the third upper limit value is less than the first threshold or a second threshold based on the third upper limit value before the switch connected to the power storage module of the connection candidate is turned on.
3 . The management device according to claim 1 , wherein
when power supply from the plurality of power storage modules to the load is started, a switch connected to a power storage module with a highest open circuit voltage among the plurality of power storage modules is turned on, and
a power storage module with the highest open circuit voltage among the one or more remaining power storage modules whose switches are in an off state, is a connection candidate connected to a switch to be turned on next.
4 . A power supply system comprising:
the management device according to claim 1 , and
the plurality of power storage modules each connected in parallel to the load via the corresponding switch.
5 . The power supply system according to claim 4 , wherein
the load is a motor of a moving body, and
the management device notifies a controller in the moving body of the upper limit value of current or power allowed to be supplied from all of the plurality of power storage modules to the motor.