Power storage system
A power storage system includes: a battery; a voltmeter configured to measure voltage of the battery; an ammeter configured to measure current of the battery; and processing circuitry configured to control charge of the battery to prevent charging power exceeding charging power upper limit from being supplied to the battery. The processing circuitry is further configured to: calculate first charging power, at which the battery reaches voltage upper limit, based on estimated open-circuit voltage, which is an estimated value of open-circuit voltage of the battery, and first estimated internal resistance; calculate second charging power, at which the battery reaches the voltage upper limit, based on the voltage, the current, and second estimated internal resistance; and set the charging power upper limit, based on the first charging power and the second charging power.
1 . A power storage system comprising:
a battery;
a voltmeter configured to measure a voltage of the battery;
an ammeter configured to measure a current of the battery; and
processing circuitry configured to control charge of the battery to prevent a charging power exceeding a charging power upper limit from being supplied to the battery, wherein
the processing circuitry is further configured to:
calculate a first charging power, at which the battery reaches a voltage upper limit, based on an estimated open-circuit voltage, which is an estimated value of an open-circuit voltage of the battery, and a first estimated internal resistance, which is an estimated value of an internal resistance of the battery;
calculate a second charging power, at which the battery reaches the voltage upper limit, based on the voltage, the current, and a second estimated internal resistance, which is an estimated value of an internal resistance of the battery; and
set the charging power upper limit, based on the first charging power and the second charging power,
the processing circuitry is configured to set, according to the present voltage, the charging power upper limit to the first charging power, to the second charging power, or to an intermediate charging power, which is between the first and the second charging power,
the intermediate charging power is the weighted sum of the first and the second charging power with a first and a second weights, and
the first and the second weights vary according to the present voltage.
2 . The power storage system according to claim 1 , wherein
the processing circuitry is configured to set the charging power upper limit to:
the first charging power when the present voltage is within a first range, which ranges from the estimated open-circuit voltage to a combination-start voltage, which is larger than the estimated open-circuit voltage is;
the intermediate charging power when the present voltage is within a second range, which ranges from the combination-start voltage to a combination-end voltage, which is larger than the combination-start voltage is; and
the second charging power when the present voltage is within a third range, which ranges from the combination-end voltage to the voltage upper limit, which is larger than the combination-end voltage is.
3 . The power storage system according to claim 2 , wherein
the combination-start and the combination-end voltage depend on a difference between the estimated open-circuit voltage and the voltage upper limit.
4 . The power storage system according to claim 1 , wherein
the closer the present voltage gets to the voltage upper limit, the smaller the first weight, and
the closer the present voltage gets to the voltage upper limit, the larger the second weight.
5 . A power storage system comprising:
a battery;
a voltmeter configured to measure a voltage of the battery;
an ammeter configured to measure a current of the battery; and
processing circuitry configured to control discharge of the battery to prevent a discharging power exceeding a discharging power upper limit from being discharged from the battery, wherein
the processing circuitry is further configured to:
calculate a first discharging power, at which the battery reaches a voltage lower limit, based on an estimated open-circuit voltage, which is an estimated value of an open-circuit voltage of the battery, and a first estimated internal resistance, which is an estimated value of an internal resistance of the battery;
calculate a second discharging power, at which the battery reaches the voltage lower limit, based on the voltage, the current, and an estimated internal resistance, which is an estimated value of an internal resistance of the battery; and
set the discharging power upper limit, based on the first and the second discharging power,
the processing circuitry is configured to set, according to the present voltage, the charging power upper limit to the first charging power, to the second charging power, or to an intermediate charging power, which is between the first and the second charging power,
the intermediate charging power is the weighted sum of the first and the second charging power with a first and a second weights, and
the first and the second weights vary according to the present voltage.