Bus insulating resistance measuring device and method of power battery pack

The invention discloses a bus insulating resistance measuring device of a power battery pack, comprising a positive bus, a negative bus, a first voltage dividing circuit for generating a first voltage division output signal integrally, a first gating switch for controlling the on-off of a positive bus circuit, a second voltage dividing circuit for generating a second voltage dividing output signal, a second gating switch for controlling the on-off of a negative bus circuit, and a control unit used for controlling the on-off of the first and the second gating switches and calculating the insulating resistances of the positive and negative buses according to the first voltage division output signal and the second voltage division output signal. The invention further discloses a measuring method for the bus insulating resistance of the power battery pack, comprising the following steps: circularly sampling voltage of the battery pack, earthing voltage of the positive bus, voltage of the battery pack, earthing voltage of the negative bus in sequence; estimating the estimation value of the earthing voltage of the positive bus and the earthing voltage of the negative bus at the moment of sampling the voltage of the battery pack; calculating the insulating resistance of the positive bus and the insulating resistance of the negative bus. By using the bus insulating resistance measuring device, the measurement error is reduced.