Liu Chunhua

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

Doctor of Philosophy

About

295
Publications
141,560
Reads
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6,412
Citations
Introduction
Chunhua Liu is a senior member of IEEE. His research interests include electric machines and drives, electric vehicles and aircrafts, electric robotics and ships, electric propulsion systems, and power electronics. Dr. Liu is currently an Associate Editor of IEEE TIE, Editor of IEEE TVT, and Editor of IEEE TEC. Also, he is Editor of Energies, Subject Editor of IET – Renewable Power Generation. In addition, he is Founder & Chair of both HK Chapter, IEEE VTS and HK &Guangzhou Chapter, IEEE IES.
Additional affiliations
August 2015 - May 2016
The University of Hong Kong
Position
  • Professor (Assistant)

Publications

Publications (295)
Article
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...
Article
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...
Poster
Full-text available
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,...
Article
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...
Article
Full-text available
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...
Poster
Full-text available
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...
Patent
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Poster
Full-text available
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...
Article
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...
Article
Full-text available
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...
Conference Paper
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Three-phase wireless power transfer (WPT) systems have compact coil structures, canceled triplen harmonics, and less dc-link current ripple, which are suitable for wireless electric vehicle (EV) charging systems. Most three-phase WPT systems are based on two-level inverters. Alternately, three-level inverters have the potential to further promote t...
Article
Recently, detecting the magnet defect fault in permanent magnet synchronous generators (PMSGs) is still challenging. The previous work mainly focuses on the phase current, back electromotive force, or searching coils. However, these methods are sometimes limited due to the machine configuration, being computationally complex, or even being intrusiv...
Article
The performance of model predictive control mainly depends on the accuracy of model and parameters, such as the back EMF harmonics in dual three-phase PMSMs. However, the back EMF harmonics would vary with the operation conditions. Thus, the parameter mismatches in the harmonic subspace would be inevitable. In this paper, a direct harmonic current...
Article
Multi-physics modelling and analysis are classic but vital problems for permanent magnet brushless (PMBL) machine design. Bulk of studies give analysis but lack modelling guidelines, comparisons, and rational validations. Accordingly, the principal objective of this article is to systematically investigate the accuracy and rationality among five pr...
Article
The additional harmonic currents in multiphase permanent magnet synchronous motors (PMSM) have been widely discussed and suppressed by the virtual vectors. However, the concept of virtual vectors would result in an increasing in the switching frequency and losing the controllability in the harmonic subspace. In this paper, a novel direct modulation...
Article
Unprecise voltage vectors applied in conventional model predictive control (MPC) would cause additional ripples in electromagnetic torque. To eliminate the problem, this paper proposes an improved model predictive torque control (MPTC) based on deadbeat solution and discrete space-vector modulation (DSVM) for dual three-phase permanent magnet synch...
Article
Harmonic suppression plays a key role in the current control of dual-three-phase (DTP) permanent magnet synchronous machines (PMSMs). Existing current control schemes are scarcely verified by designed DTP motor prototypes or consider the impact of inherent electromotive force (EMF) harmonics quantitatively. Also, few studies discuss the low-reactan...
Article
Full-text available
This paper presents a high-fidelity analytical solution and a fast integrated optimization method for vernier machines. Firstly, a harmonic modeling method (HMM) is adopted to obtain the magnetic field distribution of vernier machines. Particularly, the stator teeth of vernier machines are divided into several blocks to take account of the local ma...
Article
Transportation electrification has attracted much attention in modern society. Among all electrified transportation tools, electric vehicle (EV) is absolutely the one that has great potential to compete with and further take the place of traditional fossil fuel vehicles. This article is to outline and investigate advanced electric machines and thei...
Article
Full-text available
This article presents a harmonic modeling method (HMM) for coaxial magnetic gears (CMGs) by considering the nonlinear B – H curve for soft-magnetic material. CMGs are divided into several annular layers, where Maxwell equation is solved. A convolution matrix of permeability is introduced to obtain the relationship between the magnetic flux densi...
Article
Based on the electromagnetic-structural coupling analysis, this paper proposes the comparative study of three double-stator interior- permanent magnet vernier (DS-IPMV) machines, including the spoke-PM, V-shape-PM (V-PM) and H-shape-PM (H-PM) rotor structures. DS cooperation strategies are adopted in the machine design for the performance improveme...
Article
This paper is to present the design, analysis and verification of a new hybrid wireless power transfer (HWPT) system, which has a space-saving coupler structure. The key of the design is to simplify two coupling capacitor plates into one single frame-shaped plate at each side. Then, the coupling coil for inductive power transfer (IPT) is embedded i...
Article
In permanent magnet synchronous motor (PMSM), the winding current consists of different orders of harmonics due to the manufacture error, deadtime and disturbances. This paper proposes a winding current harmonic suppression method for PMSM by reducing the dominant fifth and seventh order current ripples. First, with reference frame transformation,...
Article
Full-text available
Open-winding (OW) PMSM could obtain the higher bus voltage utilization and more robustness against the component damage and faults. However, the additional torque ripples and THD caused by zero-sequence current would limit the further applications of OW-PMSM. In this paper, a novel model predictive two-target current control (MPTCC) scheme is prese...
Article
This paper presents a new direct load voltage control method for electrolytic capacitor-less wireless power transfer (WPT) system without DC/DC converter. In specific, the three-phase low frequency AC (LFAC) to the high frequency AC (HFAC) converter is employed into the electrolytic capacitor-less WPT system by using the bidirectional power switche...
Article
Full-text available
Monitoring power quality in microgrids is gaining increasing attention in recent years due to the popularity of microgrids and power quality disturbances caused by renewable energies. Many techniques based on artificial neural networks (ANNs) are proposed for monitoring the power quality with no need to pre-set thresholds. However, the necessity of...
Article
Full-text available
In this paper, a new dual-modulator magnetic-geared machine (DM-MGM) is proposed for tidal power generation with the virtue of high torque output at low speed. Firstly, the requirement of DM-MGM for tidal power generation is derived. Then, the flux modulation principle and flux-enhancing effect of the extra modulator of the proposed DM-MGM are elab...
Article
Full-text available
This paper proposes the permeance and inductance modelling of a new double-stator hybrid-excited flux-switching permanent-magnet (DSHE-FSPM) machine. Firstly, based on the machine design, the DS coupling analysis is presented, which refers to the mutual influence between double stators. Actually, different coupling degree leads to different modelli...
Article
Full-text available
With ever-increasing concerns on health and environmental safety, there is a fast-growing interest in new technologies for medical devices and applications. Particularly, wireless power transfer (WPT) technology provides reliable and convenient power charging for implant medical devices without additional surgery. For those WPT medical systems, the...
Article
Full-text available
In this paper, a new double-rotor multi-winding machine (DRMWM) that utilizes the flux modulation principle is proposed for propulsion system of hybrid electric aircrafts (HEAs). First, the operation principle of DRMWMs and the corresponding HEA propulsion configuration are introduced, where different operation modes of two rotors and three sets of...
Article
Full-text available
High-performance propulsion motors for more electric aircrafts (MEAs) are highly appreciated in transportation electrification. For the widely adopted permanent magnet synchronous machines (PMSMs) for MEA propulsion, the segmented Halbach magnetization has distinct merit that it contributes to sinusoidal air-gap magnetic fields for smooth operation...
Article
Full-text available
This paper studies the rotational movement and charging torque in a new reconfigured on-board charger during charging process. Recently, the reconfigured on-board charger becomes attractive, because the propulsive units are engaged in the charging system to reduce the cost and volume. Since the unbalanced currents flow through three-phase permanent...
Article
Parameter mismatches in control scheme would cause the additional harmonic components and torque ripples in PMSM. Moreover, there is additional leakage inductance mismatch in dual three-phase PMSM when comparing with its three-phase counterparts. Then, in order to release the parameter dependence of model predictive control (MPC) in application of...
Article
Most of the existing one-to-multiple wireless power transfer systems are single-channel one-to-multiple wireless power transfer (SOWPT) systems. They only utilize one power channel to charge multiple receivers. In this article, a novel multichannel one-to-multiple wireless power transfer (MOWPT) system is proposed, which can deliver power to differ...
Article
Full-text available
This study presents an analytical sub‐domain model for the prediction of various electromagnetic parameters of magnetic‐geared double‐rotor machine (MGDRM). By dividing the MGDRM into six sub‐domains and solving the Maxwell equations in polar coordinates for each region, the vector magnetic potential distribution can be derived. Subsequently, the f...
Article
Full-text available
The paper proposes the DC-biased operation of a new double-stator hybrid flux switching permanent magnet (DSH-FSPM) machine. Through directly injecting the DC current into the armature windings, the DC-biased strategy contributes both the flux enhancing (FE) and flux weakening (FW) capabilities into the proposed machine design. Firstly, the machine...
Article
Full-text available
Permanent Magnet Vernier (PMV) machine has been welcomed for direct-drive applications recently. Also, the fault tolerance is critical for special machine design in hostile conditions. This paper proposes an efficient PMV machine with the modular winding configuration, which takes the fault-tolerant capability into account, especially the open-circ...
Article
Full-text available
In this article, a direct grid-connected servo system without a dc-link capacitor is proposed for multiphase machines. First, the modeling and field-oriented control are elaborated for the direct grid-connected multiphase servo system. Then, the space current vector modulation and the vector coordination under pulsewidth-modulated (PWM) dc-link vol...
Article
Full-text available
The power split system is the key power transmission component in hybrid electric vehicles (HEVs). This article presents a new interior consequent-pole permanent-magnet (PM) magnetic-geared double rotor machine (ICPMDM) with a double rotor structure, which is suitable as the power split system for HEVs. Since the common existing magnetic-geared dou...
Article
This paper presents a wireless power transfer (WPT) system, which can deliver the power to multiple receivers concurrently with the additional resonant frequencies and reduced power switches. It employs three-phase high frequency inverter with delta type transmitting tanks. In this way, this WPT system can transfer the power with different resonant...
Article
Full-text available
Flux-modulated double-rotor (FMDR) machine topology has recently attracted much attention, particularly for the hybrid electric vehicle (HEV) propulsion. To maintain the driving stability and safety of the vehicle, the analysis of the magnetic force and the evaluation of the vibration performance for such kind of machine are indispensable. However,...