Insulation detection circuit, detection method and battery management system

An insulation detection circuit, comprising:

• an isolation power module, a first sampling module, a first sampling point, a second sampling module, a second sampling point and a processor, wherein,
• a first terminal of the first sampling module is connected to a positive electrode of a battery pack to be detected and a first terminal of a positive switch module respectively, a second terminal of the first sampling module is connected to a negative electrode of the battery pack to be detected and a first terminal of a negative switch module respectively, a third terminal of the first sampling module is connected to a first reference voltage end, and the first sampling module is configured to provide a first sampled signal for the first sampling point;
• a first terminal of the second sampling module is connected to a second terminal of the positive switch module and a positive electrode of the isolation power module respectively, a second terminal of the second sampling module is connected to a second terminal of the negative switch module and a negative electrode of the isolation power module respectively, a third terminal of the second sampling module is connected to a second reference voltage end, and the second sampling module is configured to provide a second sampled signal for the second sampling point;
• and
• the processor is connected to the first sampling point and the second sampling point respectively, the processor is configured to obtain, according to the first sampled signal, an insulation resistance value of a positive high voltage circuit at a side where the battery pack to be detected is located relative to the first reference voltage end and an insulation resistance value of a negative high voltage circuit at the side where the battery pack to be detected is located relative to the first reference voltage end, and obtain, according to the second sampled signal, an insulation resistance value of a positive high voltage circuit at a side where a load is located relative to the second reference voltage end and an insulation resistance value of a negative high voltage circuit at the side where the load is located relative to the second reference voltage end,
• wherein, the isolation power module comprises an insulation power driving unit and a transformer connected to each other;
• the isolation power driving unit is powered by a direct current voltage source or a battery pack;
• and
• the isolation power driving unit and the transformer are configured to process an output voltage of the direct current voltage source or the battery pack to supply power to the positive electrode and the negative electrode of the isolation power module.