Failure detection circuit for pre-charging relay

The invention discloses a pre-charging relay failure detection circuit. A power supply supplies power to a load, two ends of the power supply are connected in parallel with a post-stage capacitor, a pre-charging resistor is arranged on a charging loop of the post-stage capacitor, two ends of the pre-charging resistor are connected in parallel with a pre-charging relay, a control circuit outputs a pre-charging relay control signal, and a switch of the pre-charging relay is controlled through an isolation driving circuit; the sampling comparison circuit is used for detecting the voltage difference between the two ends of the pre-charging resistor, the control circuit receives an output signal of the sampling comparison circuit through the isolation output circuit, the output signal indicates whether the pre-charging relay fails or not, and the failure of the pre-charging relay comprises non-actuation or unreliable actuation of a relay coil. According to the invention, the low-cost comparator chip and the isolat