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When the permanent magnet synchronous motor (PMSM) operates at low carrier ratio, the decoupling capability and dynamic performance of the proportional-integral (PI) controller are limited by the digitization delay. In this paper, a deadbeat PI controller is proposed by modified the feedforward. With the modified feedforward, the open-loop transfer function can eliminate imaginary components. Thereby the full decoupling of $d$ and $q$ is realized. At the same time, the controller also has full control over the location of the closed-loop poles, indicating that it can have a deadbeat response for the command tracking. For the disturbance rejection, the controller allows us to select the speed with which the controller can cancel the effect of a disturbance. Further considering that the motor parameters are inaccurate, by designing the controller coefficients with the maximum value of the closed-loop poles, the current-loop can ensure the dynamic performance and harmonic suppression ability. Finally, the effectiveness of the proposed controller is verified by the simulations and experiments.
Zhijian Zhang; Long Jing; Xuezhi Wu; Wenzheng Xu; Jingdou Liu; Gege Lyu; Zilian Fan. A Deadbeat PI Controller With Modified Feedforward for PMSM Under Low Carrier Ratio. IEEE Access 2021, 9, 63463 -63474.
AMA StyleZhijian Zhang, Long Jing, Xuezhi Wu, Wenzheng Xu, Jingdou Liu, Gege Lyu, Zilian Fan. A Deadbeat PI Controller With Modified Feedforward for PMSM Under Low Carrier Ratio. IEEE Access. 2021; 9 ():63463-63474.
Chicago/Turabian StyleZhijian Zhang; Long Jing; Xuezhi Wu; Wenzheng Xu; Jingdou Liu; Gege Lyu; Zilian Fan. 2021. "A Deadbeat PI Controller With Modified Feedforward for PMSM Under Low Carrier Ratio." IEEE Access 9, no. : 63463-63474.
Traditional speed control of permanent magnet synchronous motors (PMSMs) includes a cascaded speed loop with proportional-integral (PI) regulators. The output of this outer speed loop, i.e. electromagnetic torque reference, is in turn fed to either the inner current controller or the direct torque controller. This cascaded control structure leads to relatively slow dynamic response, and more importantly, larger speed ripples. This paper presents a new dual cost function model predictive direct speed control (DCF-MPDSC) with duty ratio optimization for PMSM drives. By employing accurate system status prediction, optimized duty ratios between one zero voltage vector and one active voltage vector are firstly deduced based on the deadbeat criterion. Then, two separate cost functions are formulated sequentially to refine the combinations of voltage vectors, which provide two-degree-of-freedom control capability. Specifically, the first cost function results in better dynamic response, while the second one contributes to speed ripple reduction and steady-state offset elimination. The proposed control strategy has been validated by both Simulink simulation and hardware-in-the-loop (HIL) experiment. Compared to existing control methods, the proposed DCF-MPDSC can reach the speed reference rapidly with very small speed ripple and offset.
Ming Liu; Jiefeng Hu; Ka Wing Chan; Siu Wing Or; Siu Lau Ho; Wenzheng Xu; Xian Zhang. Dual Cost Function Model Predictive Direct Speed Control With Duty Ratio Optimization for PMSM Drives. IEEE Access 2020, 8, 126637 -126647.
AMA StyleMing Liu, Jiefeng Hu, Ka Wing Chan, Siu Wing Or, Siu Lau Ho, Wenzheng Xu, Xian Zhang. Dual Cost Function Model Predictive Direct Speed Control With Duty Ratio Optimization for PMSM Drives. IEEE Access. 2020; 8 ():126637-126647.
Chicago/Turabian StyleMing Liu; Jiefeng Hu; Ka Wing Chan; Siu Wing Or; Siu Lau Ho; Wenzheng Xu; Xian Zhang. 2020. "Dual Cost Function Model Predictive Direct Speed Control With Duty Ratio Optimization for PMSM Drives." IEEE Access 8, no. : 126637-126647.
Three-phase Z-source inverters provide a solution of voltage boosting by a single-stage topology. They are also capable of bi-directional operation as rectifiers, thus have great potential for applications in the field of transportation electrification such as Vehicle-to-Grid (V2G) chargers. In this paper, three new modulation schemes for three-phase Z-source converters are proposed and investigated. The best performed one is further developed to a closed-loop PI control method. While the voltage conversion ratio is flexible, the output voltage Total Harmonics Distortion (THD) is below 3% within the voltage ratio range of 0.5 to 2.5. The effectiveness of the proposed method has been fully validated in MATLAB/Simulink simulations and RTLAB Hardware-In-Loop (HIL) experiments based on the realtime simulator OPAL-RT OP4510. Compared to existing control methods, the proposed one performs better with reduced harmonics, flexible voltage gain, and simpler control algorithm.
Wenzheng Xu; Ka Wing Chan; Siu Wing Or; Siu Lau Ho; Ming Liu. A Low-Harmonic Control Method of Bidirectional Three-Phase Z-Source Converters for Vehicle-to-Grid Applications. IEEE Transactions on Transportation Electrification 2020, 6, 464 -477.
AMA StyleWenzheng Xu, Ka Wing Chan, Siu Wing Or, Siu Lau Ho, Ming Liu. A Low-Harmonic Control Method of Bidirectional Three-Phase Z-Source Converters for Vehicle-to-Grid Applications. IEEE Transactions on Transportation Electrification. 2020; 6 (2):464-477.
Chicago/Turabian StyleWenzheng Xu; Ka Wing Chan; Siu Wing Or; Siu Lau Ho; Ming Liu. 2020. "A Low-Harmonic Control Method of Bidirectional Three-Phase Z-Source Converters for Vehicle-to-Grid Applications." IEEE Transactions on Transportation Electrification 6, no. 2: 464-477.
This paper proposes a series of new control methods for single-phase Z-source inverters. A detailed description of the concept and principle of each method is first presented, then a comparison among them is conducted comprehensively. Afterwards, an optimized closed-loop control scheme with better harmonic elimination performance is derived. Experimental results obtained from a 1kW un-isolated Z-source inverter prototype have demonstrated the effectiveness of the proposed control method. Compared to the conventional boost control, the proposed scheme has better performance with reduced harmonics, more flexible voltage gain, and simple algorithm.
Wenzheng Xu; Ming Liu; Junwei Liu; Ka Wing Chan; Ka Wai Eric Cheng. A Series of New Control Methods for Single-Phase Z-Source Inverters and the Optimized Operation. IEEE Access 2019, 7, 113786 -113800.
AMA StyleWenzheng Xu, Ming Liu, Junwei Liu, Ka Wing Chan, Ka Wai Eric Cheng. A Series of New Control Methods for Single-Phase Z-Source Inverters and the Optimized Operation. IEEE Access. 2019; 7 ():113786-113800.
Chicago/Turabian StyleWenzheng Xu; Ming Liu; Junwei Liu; Ka Wing Chan; Ka Wai Eric Cheng. 2019. "A Series of New Control Methods for Single-Phase Z-Source Inverters and the Optimized Operation." IEEE Access 7, no. : 113786-113800.
Junwei Liu; Wenzheng Xu; Ka Wing Chan; Ming Liu; Xian Zhang; Nelson Hon Lung Chan. A Three-Phase Single-Stage AC–DC Wireless-Power-Transfer Converter With Power Factor Correction and Bus Voltage Control. IEEE Journal of Emerging and Selected Topics in Power Electronics 2019, 8, 1782 -1800.
AMA StyleJunwei Liu, Wenzheng Xu, Ka Wing Chan, Ming Liu, Xian Zhang, Nelson Hon Lung Chan. A Three-Phase Single-Stage AC–DC Wireless-Power-Transfer Converter With Power Factor Correction and Bus Voltage Control. IEEE Journal of Emerging and Selected Topics in Power Electronics. 2019; 8 (2):1782-1800.
Chicago/Turabian StyleJunwei Liu; Wenzheng Xu; Ka Wing Chan; Ming Liu; Xian Zhang; Nelson Hon Lung Chan. 2019. "A Three-Phase Single-Stage AC–DC Wireless-Power-Transfer Converter With Power Factor Correction and Bus Voltage Control." IEEE Journal of Emerging and Selected Topics in Power Electronics 8, no. 2: 1782-1800.
Ming Liu; Ka Wing Chan; Jiefeng Hu; Wenzheng Xu; Jose Rodriguez. Model Predictive Direct Speed Control With Torque Oscillation Reduction for PMSM Drives. IEEE Transactions on Industrial Informatics 2019, 15, 4944 -4956.
AMA StyleMing Liu, Ka Wing Chan, Jiefeng Hu, Wenzheng Xu, Jose Rodriguez. Model Predictive Direct Speed Control With Torque Oscillation Reduction for PMSM Drives. IEEE Transactions on Industrial Informatics. 2019; 15 (9):4944-4956.
Chicago/Turabian StyleMing Liu; Ka Wing Chan; Jiefeng Hu; Wenzheng Xu; Jose Rodriguez. 2019. "Model Predictive Direct Speed Control With Torque Oscillation Reduction for PMSM Drives." IEEE Transactions on Industrial Informatics 15, no. 9: 4944-4956.
Electric motors have a wide range of applications in a diverse range of industries. This paper presents a novel magnetic resonant coupling motor (MRCM) constructed without any iron or permanent-magnet core, i.e. a novel coreless and magnetless electric motor. Different from the conventional operation principle of existing electric motors, the application of the wireless power transfer (WPT) system using magnetic resonant coupling (MRC) technology is the key feature of the proposed MRCM. By adjusting the excitation frequency in accordance with the trajectory of resonant frequency splitting, a large electromagnetic force in different direction can be developed. Besides, the proposed MRCM has an inherent merit of unity power factor. This paper presents a new design concept, which could well be a promising start for a new generation of future electric motor.
Ming Liu; Ka Wing Chan; Jiefeng Hu; Qifang Lin; Junwei Liu; Wenzheng Xu. Design and Realization of a Coreless and Magnetless Electric Motor Using Magnetic Resonant Coupling Technology. IEEE Transactions on Energy Conversion 2019, 34, 1200 -1212.
AMA StyleMing Liu, Ka Wing Chan, Jiefeng Hu, Qifang Lin, Junwei Liu, Wenzheng Xu. Design and Realization of a Coreless and Magnetless Electric Motor Using Magnetic Resonant Coupling Technology. IEEE Transactions on Energy Conversion. 2019; 34 (3):1200-1212.
Chicago/Turabian StyleMing Liu; Ka Wing Chan; Jiefeng Hu; Qifang Lin; Junwei Liu; Wenzheng Xu. 2019. "Design and Realization of a Coreless and Magnetless Electric Motor Using Magnetic Resonant Coupling Technology." IEEE Transactions on Energy Conversion 34, no. 3: 1200-1212.
Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS) and Zero Voltage Switching (ZVS) in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.
Wenzheng Xu; Nelson Hon Lung Chan; Siu Wing Or; Siu Lau Ho; Ka Wing Chan. A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range. Energies 2017, 10, 1532 .
AMA StyleWenzheng Xu, Nelson Hon Lung Chan, Siu Wing Or, Siu Lau Ho, Ka Wing Chan. A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range. Energies. 2017; 10 (10):1532.
Chicago/Turabian StyleWenzheng Xu; Nelson Hon Lung Chan; Siu Wing Or; Siu Lau Ho; Ka Wing Chan. 2017. "A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range." Energies 10, no. 10: 1532.
Wireless power transfer (WPT) has drawn more and more attention and has many applications, such as wireless electric vehicle charging systems, which require high power, high efficiency, and high power factor. In this paper, a single-stage WPT resonant converter with bridgeless boost power-factor-correction (PFC) rectifier is proposed to improve efficiency and power quality of line input, and reduce production cost and complexity for high-power WPT system. The bridgeless single-stage topology is creatively proposed to apply in WPT system, which is much more advantageous than conventional two-stage WPT converter with individual boost PFC stage.
Junwei Liu; Ka Wing Chan; Chi Yung Chung; Nelson Hon Lung Chan; Ming Liu; Wenzheng Xu. Single-Stage Wireless-Power-Transfer Resonant Converter With Boost Bridgeless Power-Factor-Correction Rectifier. IEEE Transactions on Industrial Electronics 2017, 65, 2145 -2155.
AMA StyleJunwei Liu, Ka Wing Chan, Chi Yung Chung, Nelson Hon Lung Chan, Ming Liu, Wenzheng Xu. Single-Stage Wireless-Power-Transfer Resonant Converter With Boost Bridgeless Power-Factor-Correction Rectifier. IEEE Transactions on Industrial Electronics. 2017; 65 (3):2145-2155.
Chicago/Turabian StyleJunwei Liu; Ka Wing Chan; Chi Yung Chung; Nelson Hon Lung Chan; Ming Liu; Wenzheng Xu. 2017. "Single-Stage Wireless-Power-Transfer Resonant Converter With Boost Bridgeless Power-Factor-Correction Rectifier." IEEE Transactions on Industrial Electronics 65, no. 3: 2145-2155.
This paper proposes a new “α×β” control method modified from traditional SPWM in a basic bi-directional DC-DC Z-source converter topology which are expected to be applied in Electric Vehicle's charging and discharging. The converter can both boost and reduce the voltage in the operation of battery's discharging to the grid with this closed loop control scheme. It can also achieve charging the battery from the grid with special control of switches. PID control is adopted to improve the overall performance. Simulation results in Matlab Simulink proved the effectiveness of this control method applied on this bi-directional topology.
Wenzheng Xu; K. W. Chan; Nelson H.L. Chan; Junwei Liu. A modified control method for bi-directional Z-source converters. 2016 IEEE Transportation Electrification Conference and Expo (ITEC) 2016, 1 -7.
AMA StyleWenzheng Xu, K. W. Chan, Nelson H.L. Chan, Junwei Liu. A modified control method for bi-directional Z-source converters. 2016 IEEE Transportation Electrification Conference and Expo (ITEC). 2016; ():1-7.
Chicago/Turabian StyleWenzheng Xu; K. W. Chan; Nelson H.L. Chan; Junwei Liu. 2016. "A modified control method for bi-directional Z-source converters." 2016 IEEE Transportation Electrification Conference and Expo (ITEC) , no. : 1-7.
The amount of storage energy in comparison to the output energy for basic topologies deserves deep research which was proposed over ten years ago. It has been analyzed and demonstrated that the larger is the energy variation ratio of power devices including inductors and capacitors, the larger is power loss, thus lower efficiency. This paper extends this theory to Cuk converter and derived the energy storage variation ratio and its relationship with power loss. Simulation in conducted in PSIM platform and verified the energy ratio's impact on efficiency via detailed calculation. Finally a sample Cuk converter is built, and experiment results further demonstrated the energy ratio's relationship with power loss and efficiency from one perspective, which could help us understand and design a converter better.
Wenzheng Xu; K.W.E. Cheng. Energy storage variation ratio and power efficiency of Cuk converter in continuous mode. 2015 6th International Conference on Power Electronics Systems and Applications (PESA) 2015, 1 -6.
AMA StyleWenzheng Xu, K.W.E. Cheng. Energy storage variation ratio and power efficiency of Cuk converter in continuous mode. 2015 6th International Conference on Power Electronics Systems and Applications (PESA). 2015; ():1-6.
Chicago/Turabian StyleWenzheng Xu; K.W.E. Cheng. 2015. "Energy storage variation ratio and power efficiency of Cuk converter in continuous mode." 2015 6th International Conference on Power Electronics Systems and Applications (PESA) , no. : 1-6.
Electric vehicles (EVs) have becoming more and more popular, and although there is no doubt that motor is the key part of a functional EV, it is generally accepted that the battery is the critical component and a main obstacle of the development of EVs. In this paper, some advanced research and technology of batteries is presented and compared one by one, especially those adopted by flagship EV automakers. Some emerging batteries which have great potential for future EVs are also discussed. Based on this, the paper studies the application in EV of Cuk converter, which can be regarded as a combination of boost converter and buck converter, on the low voltage side DC supply electric vehicles together with the batteries, and even super-capacitors which have unique characteristics. Further research and design is given regarding to multi-switching of the DC-DC topology.
Wenzheng Xu; K.W.E. Cheng; K.W. Chan. Application of Cuk converter together with battery technologies on the low voltage DC supply for electric vehicles. 2015 6th International Conference on Power Electronics Systems and Applications (PESA) 2015, 1 -5.
AMA StyleWenzheng Xu, K.W.E. Cheng, K.W. Chan. Application of Cuk converter together with battery technologies on the low voltage DC supply for electric vehicles. 2015 6th International Conference on Power Electronics Systems and Applications (PESA). 2015; ():1-5.
Chicago/Turabian StyleWenzheng Xu; K.W.E. Cheng; K.W. Chan. 2015. "Application of Cuk converter together with battery technologies on the low voltage DC supply for electric vehicles." 2015 6th International Conference on Power Electronics Systems and Applications (PESA) , no. : 1-5.