Liu Chunhua

City University of Hong Kong | CityU · School of Energy and Environment

Series-end winding motor drives double the dc-link voltage utilization compared with the conventional star-connected winding counterparts, which indicates that series-end winding motor drives are suitable for high-speed applications with limited dc-link voltage. To further improve the dc-link voltage utilization and extend the speed range of the du...

Wind turbine drive trains consist of mechanical components such as the gearbox, the bearings and the rotating shaft, and an electrical component, the electric generator. These components are electromagnetically and electromechanically coupled with each other and have continuously rotating parts, making them more susceptible to faults. Unfortunately...

This is a special issue from Energies: https://www.mdpi.com/journal/energies/special_issues/U3TJHP058D There are some discounts for review and early bird technical papers.

In this letter, a novel wireless motor system, namely, the wireless ultrasonic motor system, is proposed and analyzed. A unique wireless drive topology is designed to solve the problems of the existing wireless drives, such as complex controller and converter at both the transmitting and receiving sides, regular maintenance and output ripple result...

Driving two electric motors with a five-leg voltage source inverter (FL-VSI) by connecting one phase of each motor to a common leg possesses the advantage of reducing the number of power switches. This article proposes a duty cycle allocation method to make FL-VSI use the DC bus voltage more efficiently. In this method, the motor with a smaller com...

This paper presents a half open-end winding topology based nine-leg voltage source inverter (HONL-VSI) to drive an asymmetrical six-phase permanent magnet synchronous motor (ASP-PMSM). Meanwhile, three winding connection modes (WCMs) are proposed for different output requirements. First, topology features of HONL-VSIs with three WCMs are investigat...

Existing modulation strategies for three-phase open-end winding drives (OWDs) with common dc bus usually conduct the modulations for α-β subspace and zero-sequence loop (ZSL) separately, which cannot reflect the relationship between α-β subspace and ZSL and fully utilize the dc bus voltage. To this end, this paper proposes a three-dimensional space...

A multi-motor system supplied from the reduced-switch-count voltage source inverter (VSI) is considered in this paper. Firstly, an improved multiple vectors model predictive control (MV-MPC) scheme is proposed for driving n three-phase permanent magnet synchronous motors (PMSMs) by (2 n +1)-leg VSI. To realize independent control of multi-motor,...

One-to-multiple wireless power transfer (O2M-WPT) is convenient and flexible, using a single transmitter to power multiple loads. However, existing O2M-WPT still exhibits several drawbacks: 1) the primary coil tends to burn out when there is a load open circuit or coils misalignment; 2) the compensation network cannot naturally realize constant-cur...

Series-winding three-phase PMSMs have a higher bus voltage utilization than the conventional three-phase PMSMs with star connection. This topology is suitable for applications with a limited bus voltage. However, the zero-sequence current controller will reduce the bus voltage utilization of the series-winding PMSMs, which causes problems in the fl...

Series-end winding voltage-source inverters (SEW-VSIs) can effectively improve the dc-link voltage utilization and provide the capabilities to handle the zero-sequence loop. However, the existing modulation schemes for SEW-VSIs cannot fully utilize the output capability of SEW-VSIs while guaranteeing simple implementation. To this end, a three-dime...

A dual permanent magnet synchronous motors (PMSMs) system, driven by a five-leg voltage source inverter (VSI), is considered as a feasible option for low-cost and fault tolerance application. The traditional finite-control-set model predictive control (FCS-MPC) schemes without modulator generate heavy computational burden and larger current ripple....

The underwater propulsion system (UPS) with two counter-rotating propellers is very popular now. In tradition, it needs two electric machines or additional gears, which greatly increases the volume and weight of the system. Therefore, a novel counter-rotating axial-flux permanent magnet (AFPM) machine based on magnetic-field modulation (MFM) for th...

Energy routers (ERs) are indispensable in deploying energy Internet for electric vehicles (EVs), which flexibly handle the power flow regulation. Combined with the excellent characteristic of wireless power transfer (WPT) technology for non-contact energy transmission, this paper proposes a novel wired/wireless hybrid multi-port energy router (HMER...

This paper proposes the design principle considering structural mutual effects of double-stator V-shape permanent-magnet (DS-V-PM) vernier machines for electric ship propulsion (ESP). Due to the flux concentration effect of the V-PM configuration, the double stators can be divided as a major and a minor stator, considering the different torque gene...

The series-end winding permanent magnet synchronous motor (SW-PMSM) drive system is ideal for applications with limited dc-link voltage. However, the controller design in the full-speed region for SW-PMSM is challenging because of the additional harmonic current subspaces. The harmonic currents and voltages affect the accurate solution for the opti...

Robot dogs are a new kind of transportation applied in express delivery and community patrol. The special structure makes them require high torque density and compact actuators. Then, a novel double-side asynchronous rotor axial-flux permanent magnet (DSAR-AFPM) machine is proposed for robot dogs. The 24-slot-20-pole (24S20P) and 36S42P configurati...

In this article, a novel wireless motor based on the three-phase six-stator-winding permanent magnet synchronous motor is proposed. Its wireless power transfer subsystem shares the main circuits of the wireless power transfer system and the conventional motor drive. Thus, it overcomes the natural operating frequency point mismatch between the two t...

Path planning is a computation-consuming task for autonomous ground vehicles (AGVs) in a massive indoor environment, especially for AGVs having limited computing resources. Popular path planning methods based on metric maps, like occupancy grid maps, are computationally expensive in such environments. Therefore, this paper proposes a hybrid mapping...

The widespread use of electric vehicles (EVs) has introduced many mobile energy storage devices to the power grid. Originally, this paper firstly proposes a novel concept of an EV-based virtual energy router (VER). Through utilizing the energy storage and mobility capabilities of EVs, EV-based VERs can dynamically share power supply within microgri...

Integrated Motor Drives (IMDs) have recently received extensive attention. In electric vehicles (EVs), electric propulsion aircraft, and ship propulsion systems, integrated motors have the great potential to replace traditional motors with the distinct merits of compact size, high power density, high efficiency, and high-cost effectiveness. This pa...

Following the global trend of carbon neutrality, green sustainable air transport becomes a hot topic in relevant area of applied energy. Electrified air transport propulsion system (EATPS) has received wide research interest since it can completely replace jet engines, exclude fossil fuel supply, and eliminate carbon emission during flight. As the...

This article is devoted to developing a unique series-winding drive (SWD) topology, analyzing and implementing its control schemes for asymmetrical multiphase permanent magnet synchronous motor (PMSM). Proposed SWDs have higher voltage utilization than ordinary wye or delta connection, but vary with the number of inverter legs and connection sequen...

Harmonic currents always exist in a five-phase permanent magnet synchronous machine due to some disturbances. This letter proposes a unique modulation scheme to synthesize the control voltage in the harmonic subspace, xy -space, to suppress harmonic currents actively. The advantage of the proposed modulation scheme is that it is decoupled from th...

This paper proposes a novel cascaded adaptive deadbeat (CADB) control method for permanent magnet synchronous motor (PMSM) drives. Firstly, an adaptive deadbeat (DB)-based current controller is proposed with a simplified first-order current loop dynamic model. The motor parameters are compressed into few identifiable coefficients, and an improved g...

Harmonic currents always exist in a dual three-phase permanent magnet synchronous machine (PMSM) due to the inverter nonlinearity, non-sinusoidal back-electromotive force, and external disturbances. This article proposes a deadbeat predictive harmonic current control (DPHCC) method to suppress the harmonic currents. The DPHCC method can directly ca...

The main difficulty in designing predictive controllers for permanent magnet motors with different topologies is the control of the additional current subspaces. The frequency of current components in these additional subspaces (harmonic subspaces and zero-sequence loop/subspaces) is several times the fundamental current frequency. Moreover, the in...

Thermal analysis is vital in the design stage of permanent magnet synchronous motors (PMSMs). Though recent studies have developed the thermal equivalent circuit models for internal temperature calculation, they cannot consider transient modification of thermal conditions, and have a notable drawback of low accuracy. Therefore, this study addresses...

Deadbeat-direct torque and flux control (DB-DTFC) significantly improves the torque response performance compared with the conventional direct torque control. However, the existing DB-DTFC algorithm suffers from a relatively heavy computational burden due to its intricate derivation. Thus, two simplified DB-DTFC algorithms for permanent magnet sync...

There is recognized interest in in-wheel motors for vehicle traction. Studies have gradually focused the design of in-wheel motors on electro-mechanical vibration, subject to the demand of driving comfort. It is crucial to model, analyze, and minimize the air-gap exciting force, the dominant source of vibration. In order to qualitatively and quanti...

This article proposes a novel flux weakening scheme for five-phase PMSM with active harmonic currents injection. The conventional flux weakening control schemes applied in the five-phase PMSM do not consider the voltage limit drop in the fundamental subspace due to the harmonic current controller. Thus, the derivation between the reference current...

The detection and location of eccentricity faults in a permanent magnet synchronous generator (PMSG) become increasingly essential, especially in safety-critical applications. However, the existing approaches for monitoring eccentricity subject to many limitations. In this article, a novel method for online detection and location of the eccentricit...

Traditional multichannel wireless power transfer (WPT) systems suffer from the complex system structure and cross-interference among receivers. To solve such problems, this article presents the design and control methods of a decoupled multichannel WPT system based on multilevel inverters. A single-phase multilevel inverter is utilized to drive the...

Electrified transportation tools, including electric vehicles, electric aircraft, and electric vessels, have gradually taken up an increasing share in recent decades. Development in new materials, analysis methods, power electronics, and microchips brings new opportunities and challenges to the current research on electrified transportation tools,...

With the increasing requirements and demands for electric machines in various applications, axial-flux machines (AFMs) attract more and more attention in recent years because of their unique merits of high power density, compact structure, and high material utilization. This paper mainly investigates the topologies of AFMs and corresponding modelin...

Unmanned Aerial Vehicle (UAV) propulsion technology is significantly related to the flight performance of UAVs, which has become one of the most important development directions of aviation. It should be noted that UAVs have three types of propulsion systems, namely the fuel, hybrid fuel-electric, and pure electric, respectively. This paper present...

The series-end winding PMSM drive system is a new drive topology where the phase windings are connected in series. The generic carrier-based pulse width modulation (CBPWM) solution of series-end winding PMSMs will further promote their applications and avoid the computationally complex space vector PWM in multiphase series-end winding PMSMs. Howeve...

Series-winding (SW) permanent magnet synchronous motors (PMSMs) are of increasing interest and great potential for low-voltage traction in electric vehicles because of their both higher DC voltage utilization and fewer inverter legs. A few studies attempt to promote this topology from three-phase to multi-phase frame. However, the SW topology for a...

As microgrids develop rapidly, more inverters are adopted to achieve DC/AC or AC/DC/AC conversion of distributed generators (DGs). The virtual synchronous generator (VSG) control has started to replace the traditional droop control for inverters. In order to restore the frequency to its nominal value, most existing secondary frequency control (SFC)...

Through the zero-sequence current (ZSC) hysteresis controller, the existing ZSC hysteresis control-based space vector modulation (SVM) strategy can provide a satisfactory ZSC suppression effect and greatly reduce the complexity for the open-end winding permanent magnet synchronous machine (OW-PMSM) drive with common dc bus. However, the correspondi...

Energy routers are intelligent power electronic systems that enable energy sharing and flexible power flow regulation among various distributed energy sources. Combining the excellent feature of wireless power transfer (WPT) technology for contactless transmission of electrical energy, this paper proposes a novel wireless energy router to realize t...

The open-winding permanent magnet synchronous motor (OW-PMSM) has been developed, mostly potential for low-voltage traction in electric vehicles. Yet, both the disturbance from vehicle system under driving and the motor with low-reactance (LR) feature expose the limits of traditional controllers that are prone to great current harmonics. Therefore,...

As a crucial preprocessing for motor products, design optimization methodologies have been widely explored. However, existing studies always indicate some issues. Analytical model-based optimization involves complex mechanisms. The surrogate-based optimization can hardly satisfy the accuracy of multiple objectives or in scenarios with high dimensio...

The performance of flux-weakening controllers in the multiphase PM machines depends on the accurate fundamental voltage limit derivation, and the minimal copper loss design in the flux-weakening operation region has not been well discussed. In this paper, the accurate fundamental voltage limit with considering harmonic current suppression is derive...

Home energy management system (HEMS) dynamically regulates energy production and consumption to reduce energy usage costs and increase power efficiency. By combining wireless power transfer (WPT) technology with energy routers, this paper proposes a new wireless energy router system for HEMS to realize omnidirectional cableless energy interconnecti...

To suppress the zero-sequence current and enhance the steady-state performance of the three-phase series-end winding permanent magnet synchronous motor (TPSW-PMSM) drives, a multi-vector-based model predictive current control scheme with zero-sequence current suppression is developed in this paper. The concept of the desired voltage is utilized to...

Five-phase electric machines include an $\alpha \beta$ -space and a xy -space, which should be simultaneously considered when designing the machine controller. This article proposes a unique modulation scheme based on nonlinear optimization to synthesize control voltages in both spaces. The advantage of the proposed scheme is to eliminate the i...

Much attention is paid to axial-flux permanent magnet (AFPM) machines thanks to the compactness and high torque density. However, the finite element method (FEM) for AFPM machines will cause a large computational burden during simulation. Thus, this paper proposes an improved magnetic equivalent circuit method (MECM) to predict the performances of...

The wide use of inverters in microgrids motivates the development of digital controllers with sampling systems. This paper proposes a multi-rate sampling frequency and voltage regulation method for inverters-based distributed generators (DGs). The fast-sampling signals are adopted to achieve the primary control, which is composed of the VSG-based f...

Flying electric vehicle (FEV) is an innovative and potential solution for future point-to-point transportation and urban air mobility. The propulsion system and relevant technologies are the keys for FEV realization. As the core components, novel FEV propulsion electric machines and drives are to propose a few high demands, such as high specific po...

A Method of Controlling A Drive System, A Controller for Controlling A Drive System, A Drive System And An Assembly Commprising A Controller, A Drive System And A Permanent Magenet Synchronous Motors - CityU Scholars | A Research Hub of Excellence Researcher login City University of Hong Kong City University of Hong Kong City University of Hong Kon...

The magnetic field calculation for axial flux motors (AFMs) is always intricate and time-consuming. To this end, a fast quasi-three-dimensional (3D) analytical model is proposed in this paper for magnetic field prediction in AFMs. By dividing the AFM into several annular slices in the radial direction, the 3D magnetic field problem can be simplifie...

This paper proposes a multi-virtual-vector model predictive control (MPC) for a dual three-phase permanent magnet synchronous machine (DTP-PMSM), which aims to regulate the currents in both fundamental and harmonic subspace. Apart from the fundamental α-β subspace, the harmonic subspace termed x-y is decoupled in multiphase PMSM according to vector...

This paper presents a novel magnetic-geared direct-drive machine (MGDM) with V-shaped permanent magnets (PMs) installed on its rotor. By extending the inner rotor shaft and connecting it to a prime motor, the torque and power density of the proposed MGDM is boosted. Additionally, compared with the conventional MGDM with surface-mounted PMs, the pro...

In this article, an in-depth study on eccentricities and their resultant vibration characteristics of an interior permanent magnet synchronous generator (IPMSG) for portable power generation is proposed. Also, this article introduces the eccentricity detection through vibration tests, since the vibration patterns caused by eccentricities are unique...

In this paper, a novel dual-rotor multiple-winding machine (DRMWM) is proposed for the continuous variable transmission (CVT) in hybrid electric vehicles (HEVs). First, a mathematical model of the proposed machine is constructed by using the harmonic modeling method (HMM). Then, on the basis of the magnetic field analysis, the operating principle o...

In this paper, a new compound consequent-pole double-rotor electric machine (CCPDRM) is proposed for hybrid propulsion system (HPS) application. First, the operating principle and harmonic components in CCPDRMs are elucidated. The winding factor theory for conventional permanent-magnet (PM) electric machine is further extended and applied in CCPDRM...

Transportation electrification has been widely identified as a promising solution to combat environmental pollution and greenhouse gas emissions. The gradual popularization of electric vehicles will contribute to a green transportation network that helps to reduce carbon footprint and promote carbon neutrality. Ever-growing traffic burdens and high...

Hybrid electric vehicles (HEVs) have been developed extensively thanks to the inherent merits of both internal combustion engine vehicles (ICEVs) and battery electric vehicles (BEVs). In HEVs, batteries and electric motors are introduced to help internal combustion engines improve fuel efficiency and reduce greenhouse gas (GHG) emissions. According...

Model predictive control (MPC) schemes applied in multiphase permanent magnet synchronous motors (PMSMs) should provide the precise torque output and suppress the harmonic currents at the same time. Then, the trade-off between precise torque output and harmonic currents suppression is inevitable in the finite control set MPC (FCS-MPC). To provide a...

Series-winding topology (SWT) could improve the DC-link voltage utilization, as open-winding topology does. Meanwhile, it can greatly reduce the number of power devices. Firstly, for the half-bridge power modules (HBPMs)-based inverter, an N-phase series-winding motor only requires N+1 HBPMs for driving. On the other hand, such SWT also brings new...

Series-winding topology inherits the high DC-link voltage utilization of open-winding topology and simultaneously reduces the amount of switching devices. However, there still exists a zero-sequence loop in Series-winding topology. Moreover, the zero-sequence current will be generated from both inverter side and the 3 rd harmonic back electromotive...

Compared to open-winding machine topology, series-winding topology retains the advantages of high DC-link voltage utilization and reduces the number of switching devices. However, in five-phase series-winding permanent magnet synchronous machines (FPSW-PMSMs), x-y subspace and zero-sequence harmonic components (dual harmonic components, DHC) exist...

Electric machines with high torque density are needed in many applications, such as electric vehicles, electric robotics, electric ships, electric aircraft, etc. and they can avoid planetary gears thus reducing manufacturing costs. This paper presents a novel axial-radial flux permanent magnet (ARFPM) machine with high torque density. The proposed...