A Cost-Effective Passive/Active Hybrid Equalizer Circuit Design

Chein-Chung Sun,Yu-Hua Huang,Yu-Liang Lin,Chun-Hung Chou

doi:10.3390/en15062000

Abstract

This paper proposes a novel hybrid equalizer circuit (HEC) for a battery management system (BMS) to implement the passive HEC (P-HEC), active HEC (A-HEC), or active/passive (AP-HEC) with the same equalizer circuit architecture. The advantages of an HEC are that it is simple, cost-effective, highly energy efficient, and fail safe. The P-HEC can further use a cooling fan or heater instead of a conventional resistor as a power dissipation element to convert the energy of the waste heat generated by the resistor to adjust the battery temperature. Even if the P-HEC uses the resistor to consume energy as in conventional methods, the P-HEC still dramatically improves the component lifetime and reliability of the BMS because the waste heat generated by the equalizer resistor is outside of the BMS board. Three significant advantages of an A-HEC are its (1) low cost, (2) small volume, and (3) higher energy efficiency than the conventional active equalizer circuits (AECs). In the HEC design, the MOSFETs of the switch array do not need high-speed switching to transfer energy as conventional AECs with DC/DC converter architecture because the A-HEC uses an isolated battery charger to charge the string cell. Therefore, the switch array is equal to a cell selector with a simple ON/OFF function. In summary, the HEC provides a small volume, cost-effective, high efficiency, and fail-safe equalizer circuit design to satisfy cell balancing demands for all kinds of electric vehicles (EVs) and energy storage systems (ESSs).

Highlights

Due to growing concerns about the environmental impact of fossil fuels, policymakers are increasingly turning their attention to clean energy and electric vehicles [1–5]
This paper proposed the cost-effective and simple passive/active hybrid equalizer circuit (HEC) design for a battery management system (BMS)
The key idea of the HEC is to let the switch array as a string cell selector for selecting the string cell to charge (A-HEC) or discharge (P-HEC) for cell balancing purposes

Summary

Introduction

Due to growing concerns about the environmental impact of fossil fuels, policymakers are increasingly turning their attention to clean energy and electric vehicles [1–5]. It is easy to identify the failure switch path byFdigeutreec9tisnhgowthseanbHalEaCnciminpglecmuernrteAnEt Corarvcohiltteacgtuerechbaynregpel.acing the charge unit of Figure 5 to an isolated CC-CV battery charger, which is called an A-HEC. The switch SB controls the input power, and the SA controls the charger output power to the EQ-Bus. Figure 10 shows the HEC architecture can be either PEC or AEC, but only one mode can be used at one time.

LLooww--CCoosstt BBSS--MMOOSSFFEETT DDrriivvee

Schematic and Calculation for BS-P-MOSFET Circuit In

Schematic and

Schematic and Calculation for BS-N-MOSFET Circuit

Implementation and Test

Conclusions