To improve the performance and integration of the power train of electric vehicles power, a dual three-phase permanent magnet synchronous machine (PMSM) drive is investigated to achieve hybrid energy storage system power management. Two sets of motor windings are connected with ultracapacitors and a battery, respectively, through the inverters. First, the operation modes of the integrated system are studied by modeling and vector diagram analysis. A new control scheme is then established to enhance the regulation for unbalanced winding power distribution. The approach to suppress the motor harmonics current under the unbalanced power operation is also discussed. Finally, a frequency dividing coordinated control is performed for good dynamic response and seamless transient process. Both simulation and experiment results verify the effectiveness of the proposed system and the control strategy.

This paper proposes an ultracapacitor (UC)-battery hybrid energy storage system (HESS) for electric vehicle based on asymmetric bidirectional Z-source topology. Compared with the conventional two-stage design, the HESS can be incorporated into the traction inverter system, leading to better performance and lower cost. The UC energy can be effectively utilized due to the buck/boost characteristic in the Z-source converter; meanwhile, the battery converter gets eliminated in this case. The assumption about the symmetry in the Z-source topology impendence network states for the conventional analysis no longer applies to the proposed HESS configuration. The asymmetric characteristic related with the uneven power distribution of UCs and battery is mathematically excavated in detail. The frequency dividing coordinated control is proposed to exploit the advantages of UCs and battery. The battery peak current estimation is then investigated. Finally, the steady performance and transient response in both traction and regenerative modes are verified by simulation and experimental results.

This study investigates a new hybrid energy storage system (HESS), which consists of a battery bank and an ultra-capacitor (UC) bank, and a control strategy for this system. The proposed topology uses a bi-directional DC-DC converter with a lower power rating than those used in the traditional HESS topology. The proposed HESS has four operating modes, and the proposed control strategy chooses the appropriate operating mode and regulates the distribution of power between the battery bank and the UC bank. Additionally, the control system prevents surges during mode switching and ensures that both the battery bank and the bi-directional DC-DC converter operate within their power limits. The proposed HESS is used to improve the performance of an existing power-split hybrid electric vehicle (HEV). A method for calculating the parameters of the proposed HESS is presented. A simulation model of the proposed HESS and control strategy was developed, and a scaled-down experimental platform was constructed. The results of the simulations and the experiments provide strong evidence for the feasibility of the proposed topology and the control strategy. The performance of the HESS is not influenced by the power limits of the bi-directional DC-DC converter.

Wireless charging to autonomous underwater vehicle effectively prolongs the attended time and extends the endurance mileage. As the most promising underwater power feeding technique, inductive power transfer is also faced with challenges like the attenuation in seawater, ocean current disturbance etc. Special concerns in terms of power quality, efficiency improvement and mechanical fixing need to be considered when designing the underwater electromagnetic coupling structure. An attenuation model in seawater is established in this paper. The optimal working frequency range is refined for a specific transmission media. Different from the wireless power transfer system in the air, the underwater WPT system features tight coupling between the transmitter and receiver. The optimal range of coupling coefficient needs to be re-designed, as high coupling coefficient incurs frequency splitting and the increase of harmonic component, while low coupling coefficient results in low efficiency. Based on the theoretical analysis, a self-latching coupling structure is proposed with lightweight design on receiver side. System parameters are optimized correspondingly and a 3kW experiment validates the theoretical analysis.

Four-switch buck-boost (FSBB) converter has the capability of bidirectional voltage step-down and step-up, which has attracted attentions in the fields of energy storage and solar energy. However, it faces the challenges in multi-mode operation and smooth mode transition, which rely on the complex mode detection scheme and cumbersome parameter tuning. In this paper, the inherent limitation is analyzed through inconsistent frequency response and noncontinuous duty cycle operation region aspects. Then, a model predictive control (MPC) method characterized by tuning-free cost function is presented to achieve multi-mode control and smooth transition simultaneously. With the goal of ensuring the reference current tracking under inconsistent frequency response, a duty cycle and current ripples prediction are presented for all switching combinations. Then, a tuning-free cost function is utilized to overcome the gaps in noncontinuous duty cycle operation region and a smooth mode transition is achieved. Further, the robustness of the current tracking capability is analyzed mathematically considering the inductance variation and stray resistance variation. Finally, a comparative experiment proves the effectiveness. And it shows that the method can improve the efficiency by 0.4% compared with the traditional four-mode control.

This paper proposes a torque distributed control strategy for the multiphase machines in the hybrid energy storage system (HESS) application. Different with the conventional energy current regulation method, the system energy management is researched by the machine torque distribution in different sets of windings. The load power is then afforded by the energy storage devices connected with the windings through the inverters. The principle of the distributed torque operation is explored with a dual three-phase PMSM model and the asymmetrical windings operation is explained with the flux vector diagram. The windings decoupling compensation, flux observer and parameter identification methods are presented. Based on the proposed strategy, a power frequency dividing coordinated regulation is achieved. The hybrid energy storage devices can directly response to the average or instantaneous parts in the load torque and power fluctuation. Simulation and experiments are demonstrated with different operation cases.