Dual power supply energy storage

The dual power supply is composed of battery and DC/DC converter with super-capacitor. Vehicle load transfers driveline from wheel inverter. In the DC bus, the required inverter general input power becomes the load. Figure 2 shows the energy flow of battery and dual power supply system.

The dual power supply electric vehicle is driven by the batteries as primary energy source and the super-capacitors as the assistant power source. Discarding of voltage variation, for dual power supply system, the relationship of battery, BDC with super-capacitor, and the load in power or in current can be simplified to as shown in Fig. 4.

Analyzing of the power to-fro flowing directions or two power supply charge and discharge to the load combinations, we learnt that there are 12 flow states of dual power supply totally. Nevertheless, as a matter of fact, the 8 flow states depicted in Fig. 5 cover almost all of the power mode combinations for the short distance electric vehicle.

Energy storage/reuse based on the concept of shared energy storage can fundamentally reduce the configuration capacity, investment, and operational costs for energy storage devices. Accordingly, FESPS are expected to play an important role in the construction of renewable power systems.

Concurrently, the energy storage system can be discharged at the peak of power consumption, thereby reducing the demand for peak power supply from the power grid, which in turn reduces the required capacity of the distribution transformer; thus, the investment cost for the transformer is minimized.

Because the energy from renewable sources and its associated power load exhibit highly asymmetric temporal and spatial distributions, such systems require considerable upgrades to their energy storage capabilities, which is a challenging task (Mohandes et al., 2021).