Semiconductor device for controlling a charge of a battery cell

A semiconductor device comprising:

• a controller sealed in a battery pack together with a battery cell,
• wherein the controller is configured to:
• measure, prior to starting a charging of the battery cell, a voltage of the battery cell and an end voltage of the battery pack without measuring an output voltage of a charger;
• measure a current in the battery pack;
• control the charging of the battery cell of the battery pack,
• wherein the controller generates, based on the voltage of the battery cell and the current in the battery pack measured prior to starting the charging of the battery cell, a voltage command value for setting an upper limit value of an output voltage of the charger to be used at a time of charging the battery cell and a current command value for setting an upper limit value of an output current of the charger to be used at the time of charging the battery cell,
• wherein the upper limit value of the output voltage in the voltage command value is determined by adding 1) a maximum potential voltage that the battery cell of the battery pack can be charged maximally and 2) a voltage drop value due to i) a first path impedance between a charger and an end of the battery pack and ii) a second impedance between the end of the battery pack and the battery cell of the battery pack,
• wherein the controller calculates the first path impedance between the charger and the end of the battery pack using an output voltage of the charger, an end voltage of the battery pack, and a charging current flowing through the battery pack,
• wherein the controller calculates the second impedance between the end of the battery pack and the battery cell of the battery pack using the end voltage of the battery pack, a voltage of the battery cell of the battery pack, and the charging current flowing through the battery pack,
• wherein, when the battery pack is connected to the charger, the controller transmits the generated voltage command value and current command value to the charger,
• wherein the controller uses the generated voltage command value and current command value to instruct the charger so that the upper limit value of the output voltage output from the charger is higher than a predetermined voltage which is the maximum potential voltage that the battery cell of the battery pack can be charged maximally,
• wherein the controller calculates a path impedance by adding the first and second path impedances,
• wherein the controller calculates the voltage drop value by using the output voltage from the charger, the voltage of the battery cell of the battery pack, the charging current flowing through the battery pack, and the path impedance,
• wherein methods of the charging include a constant current charge and a constant voltage charge, the constant current charge performing a constant current charging until the output voltage of the charger reaches the maximum potential voltage that the battery cell of the battery pack can be charged maximally, and the constant voltage charge setting the output voltage from the charger to the maximum potential voltage after the constant current charging, and then performing a constant voltage charging until the voltage of the battery cell of the battery pack is near the maximum potential voltage,
• wherein, during the constant current charge, the controller updates the generated voltage command value using a predetermined value set as the first path impedance, and
• wherein, during the constant voltage charge, the controller updates the generated voltage command value by updating the first path impedance by replacing the voltage command value with the output voltage of the charger.