Method of estimating maximum output of battery for hybrid electric vehicle
View Patent ↗Disclosed is a method of estimating a maximum output of a battery for a hybrid electric vehicle (HEV). The method comprises extracting maximum charge/discharge outputs of the battery depending on a plurality of charged states (SOC) of the battery under which the vehicle is able to be driven and calculating an interrelation between them; extracting maximum charge/discharge outputs of the battery at plural temperatures under which the vehicle is able to be driven, and calculating an interrelation between them; extracting degradations of outputs of the battery as a capacity of the battery is discharged during the traveling, and calculating an interrelation between them; and based on the interrelations obtained, estimating a maximum output of the battery using a function.
1. A method of estimating a maximum output of a battery for a hybrid electric vehicle comprising steps of:
extracting maximum charge or discharge outputs of the battery depending on a plurality of charged states (SOC) of the battery under which the vehicle is able to be driven and calculating an interrelation between them;
extracting maximum charge or discharge outputs of the battery at plural temperatures (temp) under which the vehicle is able to be driven, and calculating an interrelation between them;
extracting degradations of outputs of the battery as a capacity of the battery is discharged (accumulated discharge Ah) during traveling, and calculating an interrelation between them; and
based on the interrelations obtained from each of the steps, estimating a maximum output (Power max ) of the battery through a following function:
Power
max
=
F
(
SOC
,
temp
,
accumulated
discharge
Ah
)
=
F
(
SOC
,
temp
)
⨯
F
(
accumulated
discharge
Ah
)
,
wherein
F(accumulated discharge Ah)=C 5 k 5 +C 4 k 4 +C 3 k 3 +C 2 k 2 +C 1 k+C 0 , where each of C 5 ˜C 0 is constant, and
k is a discharged capacity of the battery, is within a range of [0, 300000] and is inputted with a modified value within a range of [−1, 1] when it is inputted as an input value into the function.
2. The method according to claim 1 , wherein the function, F(SOC, temp) is calculated by a following relational equation:
F (SOC, temp)= F (temp) 5 ×SOC 5 +F (temp) 4 ×SOC 4 +F (temp) 3 ×SOC 3 +F (temp) 2 ×SOC 2 +F (temp) 1 ×SOC+ F (temp) 0
where F(temp)=D 2 ×temp 2 +D 1 ×temp 1 +D 0 (D 0 ˜D 2 : constant).
3. The method according to claim 1 , wherein the degradation of the output depending on the discharged capacity of the battery is expressed by a following equation:
F (accumulated discharge Ah )=−16.3986 k 5 +15.0026 k 4 +13.307 k 3 −8.38698 k 2 −7.96289 k+ 82.3028.
4. The method according to claim 3 , further comprising a step of transmitting the estimated maximum output to a vehicle control device of the hybrid electric vehicle via a battery management system (BMS) to control the charge or discharge output of the battery.
5. The method according to claim 1 , further comprising a step of transmitting the estimated maximum output to a vehicle control device of the hybrid electric vehicle via a battery management system (BMS) to control the charge or discharge output of the battery.