Relay diagnosis circuit, diagnosis method, and battery management system

A battery management system comprising a relay diagnosis circuit for a power battery pack, wherein the relay diagnosis circuit comprises:

• a first sampling unit, a second sampling unit, a first sampling point, a second sampling point, a reference voltage terminal, and a processor,
• wherein a first end of the first sampling unit is connected with voltage output end of the power battery pack to be measured and a first end of a relay, a second end of the first sampling unit is connected with the reference voltage terminal and the first sampling point, and
• wherein the first sampling unit comprises a first switch, a first resistor network, and a second resistor network which are connected in series:
• wherein a first end of the first switch is connected with the voltage output end of the power battery pack to be measured and the first end of the relay, a second end of the first switch is connected with a first end of the first resistor network;
• wherein a second end of the first resistor network is connected with a first end of the second resistor network and the first sampling point;
• and
• wherein a second end of the second resistor network is connected with the reference voltage terminal;
• the first sampling unit is configured to provide a first sampled signal for the first sampling point by having the first switch in ON state;
• wherein a first end of the second sampling unit is connected with a second end of the relay, a second end of the second sampling unit is connected with the reference voltage terminal and the second sampling point, and
• wherein the second sampling unit comprises a second switch, a third resistor network, and a fourth resistor network which are connected in series:
• wherein a first end of the second switch is connected with the second end of the relay, and a second end of the second switch is connected with a first end of the third resistor network;
• wherein a second end of the third resistor network is connected with a first end of the fourth resistor network and the second sampling point;
• and
• wherein a second end of the fourth resistor network is connected with the reference voltage terminal;
• the second sampling unit is configured to provide a second sampled signal for the second sampling point by having the second switch in ON state;
• and
• wherein the processor is connected with the first sampling point and the second sampling point respectively, and the processor is configured to obtain a diagnosis result of the relay based on the first sampled signal and the second sampled signal when both of the first switch and the second switch are in ON state.