Abstract: A voltage balance circuit includes a battery module connected to an external power source, a voltage dividing module, a detection module and a control module. The battery module includes a plurality of batteries connected in series. The voltage dividing module includes a plurality of bleeder resistors. Each bleeder resistor is connected with one battery in parallel. The detection module includes a plurality of thermistors, fixation resistances and micro-controllers. Each thermistor is arranged beside one bleeder resistor. Each thermistor is connected with one fixation resistance in series. Each micro-controller is connected with one thermistor and the one fixation resistance. The control module includes a plurality of switches and an analog front end component. Each switch is connected with the one bleeder resistor in series. Each switch is connected to the analog front end component, and the analog front end component is connected to the one micro-controller.

Abstract: An insulation resistance measuring device for detecting insulation resistance of an electric vehicle comprises a battery system, a measuring unit, a control unit and a calculation unit. The measuring unit comprises a circuit module comprises a plurality of resistances connected between a positive side and a negative side of the battery system, a first switch, a second switch, and a voltage detecting unit. The first switch is connected between the circuit module and a ground side. The second switch is connected between the circuit module and the negative side. The voltage detecting unit is arranged at a connecting node of the resistances of the circuit module. The control unit is configured to control the first switch and the second switch to turn on or turn off. The calculation unit is configured to calculate a high potential insulation resistance and a low potential insulation resistance of the electric vehicle.