Power management system, micro-controller unit, battery management system, and battery

A battery management system (BMS), comprising:

• a power management system comprising:
• a primary power supply module, configured to be connected to a power supply and comprising a first voltage conversion unit, a first voltage monitoring unit, and a first storage unit, wherein the first voltage conversion unit is configured to generate a first voltage based on a voltage of the power supply, the first voltage monitoring unit is configured to diagnose the first voltage, and the first storage unit is configured to store a diagnosis result of the first voltage;
• a secondary power supply module, connected to the primary power supply module and comprising a second voltage conversion unit, wherein the second voltage conversion unit is configured to generate a second voltage based on the first voltage, and the second voltage being lower than the first voltage;
• and
• a micro-controller unit (MCU), connected to the primary power supply module and the secondary power supply module and configured to read the diagnosis result of the first voltage from the first storage unit and determine, based on the diagnosis result of the first voltage, whether to control the BMS to enter a safe state, the second voltage being an operating voltage of the MCU.