CURRENT DETECTION APPARATUS AND POWER SUPPLY SYSTEM

摘要

A first voltage amplifying unit (11) amplifies an end-to-end voltage of a first current detection element connected in series to a secondary battery (200). A switch unit (13) is inserted between both the ends of the first current detection element, and both the input ends of the first voltage amplifying unit (11), and performs switching between whether to supply both the input ends of the first voltage amplifying unit (11) with the end-to-end voltage of the first current detection element or with a voltage for detecting an offset voltage of the first voltage amplifying unit (11). A second voltage amplifying unit (12) amplifies an end-to-end voltage of a second current detection element connected in series to the secondary battery (200) and the first current detection element. The gain of the first voltage amplifying unit (11) is variable, and the gain of the second voltage amplifying unit (12) is constant. The output voltage of the first voltage amplifying unit (11) is used for the purpose of calculating the state of charge (SOC) of the secondary battery (200), and the output voltage of the second voltage amplifying unit (12) is used for the purpose of detecting an overcurrent of the secondary battery (200).