Device for estimating degradation of secondary cell, and method for estimating degradation of secondary cell

A secondary battery deterioration estimation device estimating deterioration of a secondary battery, comprising:

• a unit which calculates values of elements forming an equivalent circuit of the secondary battery;
• a unit which calculates a state of health (SOH) of the secondary battery based on the values of the elements forming the equivalent circuit;
• a unit which generates history information showing history of a use state of the secondary battery;
• a unit which calculates the SOH of the secondary battery based on the history information;
• a unit which determines a deterioration state of the secondary battery with reference to at least one of the SOH calculated by the values of the elements or the SOH calculated by the history information in accordance with a state of the secondary battery;
• and
• a unit which, in response to determining that a value of the SOH based on the values of the elements forming the equivalent circuit or the SOH calculated by the history information has fallen below a threshold value, switches the SOH to be referred to in accordance with the deterioration state of the secondary battery.

A secondary battery deterioration estimation method estimating deterioration of the secondary battery, comprising:

• receiving, by a programmable processor connected to a voltage sensor detecting a discharging voltage of the secondary battery and to a current sensor detecting a discharging current of the secondary battery, a first signal representing the discharging voltage from the voltage sensor;
• receiving, by the programmable processor, a second signal representing the discharging current from the current sensor;
• calculating, by the programmable processor, values of elements forming an equivalent circuit of the secondary battery based on the first and second signals;
• calculating, by the programmable processor, a state of health (SOH) of the secondary battery based on the values of the elements forming the equivalent circuit;
• generating, by the programmable processor, history information showing history of a use state of the secondary battery;
• calculating, by the programmable processor, the SOH of the secondary battery based on the history information;
• determining, by the programmable processor, a deterioration state of the secondary battery with reference to at least one of the SOH calculated by the values of the elements or the SOH calculated by the history information in accordance with a state of the secondary battery;
• in response to determining, by the programmable processor, that a value of the SOH based on the values of the elements forming the equivalent circuit or the SOH calculated by the history information has fallen below a threshold value, switching the SOH to be referred to in accordance with the deterioration state of the secondary battery;
• and
• outputting, by the programmable processor, data representing the deterioration state of the secondary battery.