Electric storage system
A reference voltage value is calculated by using a current value, a voltage value, and an internal resistance value of an electric storage apparatus. A dischargeable electric power is calculated by using the reference voltage value and a predetermined internal resistance value previously set to be higher than the internal resistance value. The dischargeable electric power is set as an allowable discharge electric power when temporarily increasing the discharge electric power required of the electric storage apparatus. The reference voltage value is calculated from the internal resistance value and is a fixed value regardless of the relationship between the current value and the voltage value. The dischargeable electric power is also constant. Since the predetermined internal resistance value is higher than the internal resistance value, the dischargeable electric power can be set while the deterioration of the electric storage apparatus is taken into account.
1. An electric storage system comprising:
a voltage sensor detecting a voltage value of an electric storage apparatus;
a current sensor detecting a current value of the electric storage apparatus; and
a controller setting an allowable discharge electric power serving as an upper limit electric power to which discharge of the electric storage apparatus is allowed,
wherein the controller uses the detected voltage value, the detected current value, and a present internal resistance value of the electric storage apparatus that is calculated based on the detected voltage value and the detected current value, to calculate a reference voltage value, the reference voltage value being the voltage value when no current flows,
the controller uses the reference voltage value and a predetermined internal resistance value to calculate a dischargeable electric power, the predetermined internal resistance value being previously set to be higher than the present internal resistance value, the dischargeable electric power being an electric power when a discharge electric power of the electric storage apparatus is increased to cause the voltage value to reach a lower limit voltage value, and
the controller sets the dischargeable electric power as the allowable discharge electric power when temporarily increasing the discharge electric power required of the electric storage apparatus.
2. The electric storage system according to claim 1 , wherein the controller calculates the dischargeable electric power based on the following expression (I):
TWout
=
(
Vb_now
+
Ib_now
×
R_now
)
-
Vb_low
R_old
×
Vb_low
(
I
)
where, in the expression (I), TWout represents the dischargeable electric power, Vb_now represents the detected voltage value, Ib_now represents the detected current value, R_now represents the present internal resistance value, Vb_low represents the lower limit voltage value, and R_old represents the predetermined internal resistance value.
3. The electric storage system according to claim 1 , wherein the controller corrects the present internal resistance value to a value lower than the present internal resistance value at present in calculating the present resistance value to calculate the dischargeable electric power during discharge of the electric storage apparatus.
4. The electric storage system according to claim 1 , wherein the controller corrects the present internal resistance value to a value higher than the present internal resistance value in calculating the present internal resistance value to calculate the dischargeable electric power during charge of the electric storage apparatus.
5. The electric storage system according to claim 1 , wherein the controller uses the present internal resistance value instead of the predetermined internal resistance value to calculate the dischargeable electric power when the present internal resistance value is higher than the predetermined internal resistance value.
6. An electric storage system comprising:
a voltage sensor detecting a voltage value of an electric storage apparatus;
a current sensor detecting a current value of the electric storage apparatus; and
a controller setting an allowable charge electric power serving as an upper limit electric power to which charge of the electric storage apparatus is allowed,
wherein the controller uses the detected voltage value, the detected current value, and a present internal resistance value of the electric storage apparatus that is calculated based on the detected voltage value and the detected current value, to calculate a reference voltage value, the reference voltage value being the voltage value when no current flows,
the controller uses the reference voltage value and a predetermined internal resistance value to calculate a chargeable electric power, the predetermined internal resistance value being previously set to be higher than the present internal resistance value, the chargeable electric power being an electric power when a charge electric power of the electric storage apparatus is increased to cause the voltage value to reach an upper limit voltage value, and
the controller sets the chargeable electric power as the allowable charge electric power when temporarily increasing the charge electric power required of the electric storage apparatus.
7. The electric storage system according to claim 6 , wherein the controller calculates the chargeable electric power based on the following expression (II):
TWin
=
(
Vb_now
+
Ib_now
×
R_now
)
-
Vb_high
R_old
×
Vb_high
(
II
)
where, in the expression (II), TWin represents the chargeable electric power, Vb_now represents the detected voltage value, Ib_now represents the detected current value, R_now represents the present internal resistance value, Vb_high represents the upper limit voltage value, and R_old represents the predetermined internal resistance value.
8. The electric storage system according to claim 6 , wherein the controller corrects the present internal resistance value to a value higher than the present internal resistance value in calculating the present internal resistance value to calculate the chargeable electric power during discharge of the electric storage apparatus.
9. The electric storage system according to claim 6 , wherein the controller corrects the present internal resistance value to a value lower than the present internal resistance value in calculating the present internal resistance value to calculate the chargeable electric power during charge of the electric storage apparatus.
10. The electric storage system according to claim 6 , wherein the controller uses the present internal resistance value instead of the predetermined internal resistance value to calculate the chargeable electric power when the present internal resistance value is higher than the predetermined internal resistance value.