Battery management system for calculating charge and disharge powers
View Patent ↗A battery management system which can output a battery state enabling optimum charge and discharge control to be performed even when a temperature variation occurs among individual single cells. A plurality of temperature sensors measure temperature values of a battery. A measurement unit measures a voltage and a current of the battery. A maximum/minimum temperature selection unit in a calculation unit determines a maximum temperature and a minimum temperature from the temperature values measured by the temperature sensors. An available power calculation unit calculates respective values of maximum available charge and discharge powers or maximum available charge and discharge currents of the battery corresponding to the maximum temperature and the minimum temperature based on the voltage and the current of the battery. A selection unit selects and outputs smaller maximum available charge and discharge powers or smaller maximum available charge and discharge currents from the respective values of the maximum available charge and discharge powers or the maximum available charge and discharge currents of the battery corresponding to the maximum temperature and the minimum temperature, which are calculated by the calculation unit.
1. A battery management system comprising:
voltage and current measuring means for measuring a voltage and a current of said battery;
calculation means for calculating respective values of maximum available charge and discharge powers or maximum available charge and discharge currents of said battery based on the voltage and the current of said battery measured by said voltage and current measuring means; and
limiter means for limiting the values of the maximum available charge or discharge powers or the maximum available charge or discharge currents, which are calculated by said calculation means, to be reduced when the voltage of said battery measured by said voltage and current measuring means is near an upper limit voltage or a lower limit voltage.
2. The battery management system according to claim 1 ,
wherein said limiter means provides a charge coefficient which takes a value of not larger than 1 when the battery voltage is increased beyond a first threshold voltage which is smaller than the upper limit voltage, and which becomes 0 when the battery voltage reaches the upper limit voltage;
said limiter means provides a discharge coefficient which takes a value of not larger than 1 when the battery voltage is decreased beyond a second threshold voltage which is larger than the lower limit voltage, and which becomes 0 when the battery voltage reaches the lower limit voltage; and
said limiter means multiplies the charge coefficient or the discharge coefficient by the maximum available charge or discharge powers or the maximum available charge or discharge currents, and limits it to be small, when the voltage of said battery measured by said voltage and current measuring means is larger than the first threshold voltage or is smaller than the second threshold voltage.
3. A battery management system comprising:
voltage and current measuring means for measuring a voltage and a current of said battery;
calculation means for calculating respective values of maximum available charge and discharge powers or maximum available charge and discharge currents of said battery based on the voltage and the current of said battery measured by said voltage and current measuring means; and
limiter means for limiting the values of the maximum available charge or discharge powers or the maximum available charge or discharge currents, which are calculated by said calculation means, which limits the values when the voltage of said battery measured by said voltage and current measuring means is near an upper limit voltage or a lower limit voltage.
4. The battery management system according to claim 3 ,
wherein said limiter means starts to limit available charge power or available charge current when the voltage of said battery measured by said voltage and current measuring means is increased beyond a first threshold voltage which is smaller than the upper limit voltage, or to limit available discharge power or available discharge current when the voltage of said battery measured by said voltage and current measuring means is decreased beyond a second threshold voltage which is larger than the lower limit voltage, and which becomes 0 when the battery voltage reaches the lower limit voltage; and
said limiter means multiplies the charge coefficient or the discharge coefficient by the maximum available charge or discharge powers or the maximum available charge or discharge currents, and limits it to be small, when the voltage of said battery measured by said voltage and current measuring means is larger than the first threshold voltage or is smaller than the second threshold voltage.
5. The battery management system according to claim 3 ,
wherein said limiter means provides a charge coefficient which takes a value of not larger than 1 when the battery voltage is increased beyond a first threshold voltage which is smaller than the upper limit voltage, and which becomes 0 when the battery voltage reaches the upper limit voltage;
said limiter means provides a discharge coefficient which takes a value of not larger than 1 when the battery voltage is decreased beyond a second threshold voltage which is larger than the lower limit voltage, and which becomes 0 when the battery voltage reaches the lower limit voltage; and
said limiter means multiplies the charge coefficient or the discharge coefficient by the maximum available charge or discharge powers or the maximum available charge or discharge currents, and limits it to be small, when the voltage of said battery measured by said voltage and current measuring means is larger than the first threshold voltage or is smaller than the second threshold voltage.