Power supplying device, power storage system, and charging method
In this power supplying device used in this power storage system, a power supplying unit charges a battery. A control unit controls the power supplying unit so as to charge the battery in a pulsed manner, in at least a part of a charging period of the battery. The control unit extends a unit on time and a unit off time when charging in the pulsed manner, as the temperature of the battery becomes lower.
1. A power supplying device comprising:
a power supplying unit that charges a battery; and
a control unit that controls the power supplying unit so as to charge the battery by pulse charging, in at least a part of a charging period of the battery;
wherein the control unit is configured to:
estimate a state of charge of a cell in the battery;
determine that a phase transition occurs based on the state of charge of the cell; and
start charging the battery by constant current charging, and switch from the constant current charging to the pulse charging in response to determining that a positive electrode material or a negative electrode material of the battery undergoes the phase transition, and
wherein the control unit is configured to extend a unit on time and a unit off time when charging the battery by the pulse charging, as a temperature of the battery becomes lower.
2. The power supplying device according to claim 1 , wherein the minimum value of the unit off time is one second.
3. The power supplying device according to claim 1 , wherein a ratio t 2 /t 1 of the unit off time t 2 to the unit on time t 1 is set in a range of 0.05≤t 2 /t 1 ≤1.0.
4. A power storage system comprising:
a battery; and
a power supplying device comprising:
a power supplying unit that charges a battery; and
a control unit that controls the power supplying unit so as to charge the battery by pulse charging, in at least a part of a charging period of the battery;
wherein the control unit is configured to:
estimate a state of charge of a cell in the battery;
determine that a phase transition occurs based on the state of charge of the cell; and
start charging the battery by constant current charging, and switch from the constant current charging to the pulse charging in response to determining that a positive electrode material or a negative electrode material of the battery undergoes the phase transition, and
wherein the control unit is configured to extend a unit on time and a unit off time when charging the battery by the pulse charging, as a temperature of the battery becomes lower.
5. The power storage system according to claim 4 , wherein a positive electrode active material of the battery is a lithium nickel composite oxide.
6. The power storage system according to claim 4 , wherein a negative electrode active material of the battery is a carbon material, silicon, a silicon compound, or a lithium alloy containing at least one element selected from the group consisting of tin, aluminum, zinc, and magnesium.
7. A charging method for charging a battery by pulse charging in at least a part of a charging period of the battery when charging the battery, comprising:
estimating a state of charge of a cell in the battery;
determining that a phase transition occurs based on the state of charge of the cell; and
starting charging the battery by constant current charging, and switching from the constant current charging to the pulse charging in response to determining that a positive electrode material or a negative electrode material of the battery undergoes the phase transition; and
extending a unit on time and a unit off time when charging the battery by the pulse charging as a temperature of the battery becomes lower.