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In order to extend fuel cell lifespan and improve fuel economy of electrical hybrid vehicle with fuel cell/battery/ultracapacitor (FCHEV), a frequency decoupling-based energy management strategy (EMS) for FCHEV using fuzzy control method is proposed. In detail, firstly, according to different characteristics of energy sources, required power of FCHEV is decomposed into three frequency ranges based on Harr wavelet transform and an adaptive-fuzzy filter. Secondly, based on the proposed frequency decoupling, the obtained three frequency required power is supplied by fuel cell-battery and ultracapacitor, respectively, which can guarantee power performance of vehicle and reduce pressure and power fluctuation on fuel cell and battery. Thirdly, for improving fuel economy, one fuzzy controller is proposed to split the power between fuel cell and battery. Finally, the proposed strategy in this paper is verified by advisor-simulink and experimental bench. Simulation and experimental results show that the proposed EMS can effectively reduce impact of power fluctuations on fuel cell, extend its lifespan and reduce fuel consumption on 7.94% compared to equivalent consumption minimization strategy.INDEX TERMS Fuel cell electric vehicle, energy management strategy, fuzzy control, frequency decoupling, fuel economy.

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Due to the friction-induced discontinuity of the clutch torque and ICE on/off, seamless mode transition of hybrid electric vehicles (HEVs) is difficult to achieve, which has a bad influence on the vehicle ride comfort. In the face of system uncontinuity and strong nonlinearity during mode switching with ICE starting, a control strategy of torque dynamic coordination is proposed by means of sliding mode control based on disturbance compensation. Firstly, the steady-state and transient models of parts and working modes are built, which improves modeling accuracy and adaptability to transient driving cycle. Furthermore, the switching process from pure electric driving to hybrid driving is divided into three phases including internal combustion engine (ICE) starting, speed synchronization and torque redistribution. The design of according disturbance observer and sliding mode controller is described in detail. Lastly, compared with other two control strategies, the rationality and validity of the control method designed are testified not only by computer simulations but also experimental tests under the comprehensive driving cycle of local passenger vehicles. The potential of the proposed control strategy in terms of power transfer smoothness and improving riding comfort is illustrated. INDEX TERMS Hybrid electric vehicle (HEV), coordinated control, sliding mode control, mode switching.