Protection system against reverse battery connection

A protection system against reverse battery connection according to an embodiment includes a controller configured to output a first square wave signal including a third square wave signal and a fourth square wave signal to an input terminal of a transformer using a first DC voltage, the transformer configured to output a second square wave signal obtained by transforming the first square wave signal, a rectifier configured to rectify the second square wave signal to output a second DC voltage, and a transistor configured to perform protection against reverse connection of a battery using the second DC voltage.