Improving Power Output of Battery and Mode Switching Frequency Based on Real-Time Average Power Method for Multi-Mode Hybrid Energy Storage System in Electric Vehicles

Bin Wang,Zhiyu Wang,Qiao Hu

doi:10.1109/access.2020.2974467

Bin Wang, Zhiyu Wang + Show 1 more

Open Access

https://doi.org/10.1109/access.2020.2974467

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Journal: IEEE Access	Publication Date: Jan 1, 2020
Citations: 39	License type: CC BY 4.0

Affiliation: Xi'an Jiaotong University, University of Canterbury

Abstract

In this paper, a power-split strategy based on a real-time average power method is developed for improving power output of battery and mode switching frequency of a multi-mode hybrid energy storage system (HESS) in electric vehicles. To achieve mode switching and power distribution for the multi-mode HESS, a rule-based strategy is designed based on the high-frequency power demand. Furthermore, a simple real-time average power method is adopted to process the high-frequency power demand. Then, the real-time average power is used as a variable logic threshold value for the power-split strategy. Since the power-split controller responds to the smooth average power rather than the high-frequency power demand, the high-frequency mode switching of the multi-mode HESS can be avoided. The ultra-capacitor works as an enhanced low-pass power filter and the battery can supply smooth and steady output power to the motor inverter. Comparative simulations between the developed power-split strategy and the rule-based strategy are performed. The advantages of the developed power-split strategy for improving the power output of the battery and the mode switching frequency of the multi-mode HESS in electric vehicles are indicated under three typical driving cycles. Moreover, the longer time duration of the real-time average power is designed, the smoother power output of the battery and the lower mode switching frequency of the multi-mode HESS can be achieved.

Highlights

Pure electric vehicles (EVs) have been considered as one of the most important parts in the sustainable transportation, due to their lower noise, lower carbon emission, and better economic performance when compared with traditional vehicles powered by internal combustion engines [1], [2]
The mode switching and the power distribution of the multimode hybrid energy storage system (HESS) will be discussed in three driving cycles, i.e., the UDDS, the New York City Cycle (NYCC), and the New European Driving Cycle (NEDC)
In the NEDC, the real-time average power is higher than the reference power at sometimes, it is smoother and lower than the power demand

Summary

INTRODUCTION

Pure electric vehicles (EVs) have been considered as one of the most important parts in the sustainable transportation, due to their lower noise, lower carbon emission, and better economic performance when compared with traditional vehicles powered by internal combustion engines [1], [2]. According to different logic threshold values of the power demand, the voltage levels of the UC and the battery, the rule-based strategy can achieve a simple power-split control for the multi-mode HESS [8], [25]. The rule-based controller cannot dynamically achieve the mode selection and power distribution for the multi-mode HESS in accordance with the high-frequency power demand. POWER-SPLIT STRATEGY BASED ON THE REAL-TIME APM As mentioned above, if the mode switching responds to the high-frequency power demand directly, the mode switching frequency might be very high It would affect the system stability of the multi-mode HESS. PURE UC DRIVING MODE The energy management (i.e., mode selection and power distribution) is the same as the aforementioned rule-based strategy

PURE BATTERY DRIVING MODE

LOW POWER DRIVING AND RECHARGING MODE

RESULTS AND DISCUSSION

CONCLUSION