Abstract: A hierarchical voltage control system is provided. A supercapacitor unit and a lithium battery unit are both connected to a DC bus to form a parallel-structure-type hybrid energy storage system, and are each configured with a power device and a switch to control a connection relationship between the corresponding unit and the DC bus. A detection circuit detects current and voltage values of the supercapacitor unit, the lithium battery unit, and the DC bus, detects an operating parameter of a power conversion system, and transmits the operating parameter to a processor, the power conversion system being connected in parallel to the DC bus for bidirectional power conversion of AC and DC energy sources. A microprocessor determines a system operating condition and uses a hierarchical voltage control strategy to control charging and discharging states of the supercapacitor unit and the lithium battery unit.

Abstract: A hierarchical voltage control system is provided. A supercapacitor unit and a lithium battery unit are both connected to a DC bus to form a parallel-structure-type hybrid energy storage system, and are each configured with a power device and a switch to control a connection relationship between the corresponding unit and the DC bus. A detection circuit detects current and voltage values of the supercapacitor unit, the lithium battery unit, and the DC bus, detects an operating parameter of a power conversion system, and transmits the operating parameter to a processor, the power conversion system being connected in parallel to the DC bus for bidirectional power conversion of AC and DC energy sources. A microprocessor determines a system operating condition and uses a hierarchical voltage control strategy to control charging and discharging states of the supercapacitor unit and the lithium battery unit.