Power management system

A power management system, comprising:

• a plurality of power units electrically connected to form a power unit string, wherein each of the power units comprises a battery module and a first switch device, and the battery module and the first switch device are serially connected to form a serial module;
• at least a second switch device having one end electrically connected to one of the power units and the other end connected to a first common node to form a discharge path;
• at least a third switch device having one end electrically connected to one of the power units and the other end connected to a second common node to form another discharge path;
• a first polarity switch unit electrically connected to the power unit string and the first common node, and outputting a first operating voltage;
• a second polarity switch unit electrically connected to the power unit string and the second common node, and outputting a second operating voltage;
• and
• a control unit electrically connected to the first switch devices, the second switch devices, the third switch devices, the first polarity switch unit, and the second polarity switch unit, wherein the control unit individually outputs a first switch signal to each of the first switch devices in accordance with a control signal, and individually controls each of the first switch devices to turn on or off;
• the control unit individually outputs a second switch signal to each of the second switch devices in accordance with the control signal, and individually controls each of the second switch devices to turn on or off to control a discharge voltage on the first common node;
• the control unit individually outputs a third switch signal to each of the third switch devices in accordance with the control signal, and individually controls each of the third switch devices to turn on or off to control a discharge voltage on the second common node;
• the control unit outputs a first adjusting signal to the first polarity switch unit to control a polarity of the first operating voltage;
• and the control unit outputs a second adjusting signal to the second polarity switch unit to control a polarity of the second operating voltage,
• wherein each of the power units further comprises a diode, which is connected in parallel to the serial module to form a parallel circuit, and the diode provides a discharge bypass path for other power units to discharge.