BATTERY INTERNAL RESISTANCE DETECTION DEVICE AND METHOD

The application relates to battery internal resistance detection device and method for power conversion device. The detection device includes a data acquisition module for acquiring a battery voltage and a battery current to obtain a DC voltage, an AC voltage, a DC current and an AC current, a first calculation module for receiving the AC current and the AC voltage at a certain instant to output a first internal resistance value and a battery capacitance, a second calculation module for receiving a plurality of DC currents and a plurality of DC voltages at multiple instants and the battery capacitance to output a second internal resistance value, and a selection module for receiving the first and second internal resistance value and selecting one of the first and second internal resistance value as battery internal resistance value. The application improves detection accuracy of battery internal resistance by combining DC and AC algorithms.