T3-3 – Thursday 13:20-15:00

13:20 Improving Dynamic Performance of Five Types of dqCDSC-PLL Using Digital Phase-Lead Compensator

Xie Menxi (Soochow University, P.R. China); Canyan Zhu (Soochow University, P.R. China); Yang Yong (School of Urban Railway Transportation, Soochow University, P.R. China)

Synchronization control is of great importance for grid-connected power converter so that precise phase angle information of the grid voltage is required. As three-phase grid voltages are imbalanced or distorted, Synchronous Reference Frame Phase-Locked Loop (SRF-PLL) aims to track fundamental frequency positive sequence with zero steady state error. The in-loop Cascaded Delayed Signal Cancellation （CDSC）in dq rotate frame used to eliminate the disturbances of phase error. Due to additional time constant induced by CDSC, the transient response of the dqCDSC-PLL is slow. As a consequence, that deteriorates the entire dynamic performance of converter. In this paper, five types of CDSC with corresponding Phase-Lead Compensators (PLC) set in loop was proposed to improve the PLL dynamic response. The simulation carried out by Matlab/Simulink verified the correctness and effectiveness. The transient track process of phase jump and harmonics are dramatically faster than before.

13:40 A Novel Axial Flux Switched Reluctance Motor with Multi-level Air Gap Geometry

Jianing Lin (McMaster University, Canada); Tim Lambert (Accelerated Systems Inc., Canada); Yinye Yang (McMaster University, Canada); Berker Bilgin (McMaster University, Canada); Rob Lankin (Accelerated Systems Inc., Canada); Ali Emadi (McMaster University, Canada)

The switched reluctance motor (SRM) is a promising drive solution for electric vehicle propulsion thanks to its simple, rugged structure, satisfying performance and low price. Among other SRMs, the axial flux SRM (AFSRM) is a strong candidate for in-wheel drive applications because of its high torque/power density and compact disc shape. In this paper, a four-phase 8-stator-pole 6-rotor-pole double-rotor AFSRM is investigated for an e-bike application. A series of analyses are conducted to reduce the torque ripple by shaping the rotor poles, and a multi-level air gap geometry is designed with specific air gap dimensions at different positions. Both static and dynamic analyses show significant torque ripple reduction while maintaining the average electromagnetic output torque at the demanded level.

14:00 Improving Electromagnetic Compatibility of Integrated Switching Converters for Hybrid/electric Vehicles

Sergio Saponara (University of Pisa, Italy); Gabriele Ciarpi (University of Pisa, Italy); Carlo Mattaliano (University of Pisa, Italy); Luca Fanucci (University of Pisa, Italy); Voicu Groza (University of Ottawa, Canada)

Practical techniques to reduce electromagnetic interference (EMI) for integrated DC/DC converters are discussed in the paper. As application case study a 48 V DC/DC converter for electric/hybrid cars is considered. Firstly, an EMI filter with very low values of inductor is designed to facilitate its integration and to reduce the overvoltage issues. Experimental results prove that the proposed EMI filter design procedure, taking into account the source and terminal impedance, avoids the state-of-art tendency of over-designing EMI filter components. Then, EMI is reduced further by integrating in the DC/DC converter a soft-start technique, which mitigates EMI issues reducing by 3 times the currents spikes at the car’s power on.

14:20 Switching Frequency Selection for Aerospace Power Converter System Considering the Design of Output LC Filter Inductor Optimizing Weight and Power Loss

Tharmini Thavaratnam (Ryerson University, Canada); Chushan Li (Ryerson University, Canada); Dewei Xu (Ryerson University, Canada)

Switching frequency is one of the main deciding factors in development of high power converter systems used in industrial applications. This paper aims at verifying the switching frequencies range between 9kHz and 20kHz by selecting and designing the inductor of the output LC filter for each switching frequency within that range while optimizing the weight and power loss of the overall power converter system used in aerospace industry. In this paper, the power loss of the inverter semiconductors is also studied for each switching frequency by considering the weight of the heat sink needed to cool the system using air as the coolant. An example design of 50kW, 540VDC, 0.8pf Motor Drive, 3 phase 2 level 400Hz system is used to analyze the results obtained using the proposed methods. The optimization of the overall power converter system weight is finalized by a trade-off between the heat sinking and filtering requirements.

14:40 D-Q Frame Optimal Control of Single Phase Grid Connected Inverter with LCL Filter

Naima Arab (ETS, Canada); Bachir Kedjar (Ecole de Technologie Supérieure, Canada); Kamal Al-Haddad (Ecole de Technologie Supérieure, Canada)

The aim of this paper is to present the design of a linear quadratic regulator (LQR) based on optimal control of single phase grid connected inverter with an LCL output filter used in solar applications. The converter model is set in the D-Q rotating reference frame. Integral action is added to the grid current in order to cancel steady state errors. The controller is tested in steady state, dynamic regime and for parameters variation. The simulation results carried out showed good performance and robustness of the adopted controller.

T4-3 – Thursday 15:20-17:00

15:20 Comparison of Si AND GaN-FETs in a VAR Compensation Application

Tanya Gachovska (Solantro Semiconductor Corp., Canada); Chris Gerolami (Solantro Semiconductor Corp, Canada)

VAR compensators (VARComps) are devices that produce reactive power in AC electrical systems. Electronic inverter circuits can supply currents that are at 90° to the grid voltage to supply reactive power Q. Since no active power P is delivered to the grid, these devices appear as a two terminal device similar to a capacitor or inductor. A VARComp was developed for this purpose. In this research, Si and GaN_HFETs were characterized in a full bridge VARComp. The Si devices have approximately twice the drain to source resistance and capacitance as compared with the GaN devices. The test results show ten times greater driver losses with Si devices as compared with GaN devices. Due to soft switching, no switching losses were observed for GaN devices. Since a GaN device does not have a body diode, diode reverse recovery losses were observed only for the Si VARComp. The transition switching time was approximately four times greater for Si FETs as compared with GAN-HFETs. The VARComp with GaN-HFETs required lower current and less time to resonate as compared with the VARComp with Si FETs and therefore had low losses. Due to the more linear transfer function of the GaN devices, as compared to Si devices, THD when operating open loop was 8% smaller. Higher total power losses were observed for the Si VARComp than the GaN VARComp.

15:40 Research on Optimal Allocation of Reactive Power Compensators in Substation

Zhichang Yuan (Tsinghua University, P.R. China)

An optimal method on allocation of reactive power compensators in substations is proposed in this paper. Equivalent circuit of 110kV substation is built up, which can model load capacity, short circuit capacity, transformer, motor in load, and power factor. Power load is modeled with composite load containing motor and constant Z load. Firstly the capacity of shunt capacitor is determined by the demand to make power factors of entirely substation equal to 1. Secondly the capacity of dynamic var source such as STATCOM or SVC is determined by the demand to prevent transient voltage collapse under faults. The capacities of reactive power compensators on different system conditions are analyzed which can be referred by power system planners and operators.

16:00 Virtual DC Machine Control Strategy of Energy Storage Converter in DC Microgrid

Shucheng Tan (Xi’an University of Technology, P.R. China); Ge Dong (School of Aerospace Engineering, Tsinghua University, Beijing, P.R. China); Hui Zhang (Xi’an University of Technology, P.R. China); Na Zhi (Xi’an University of Technology, P.R. China); Xi Xiao (Tsinghua University, P.R. China)

The bus voltage of DC microgrid is the key indicator of the stable operation of the system. The energy storage device plays an important role in maintaining the stability of the DC bus voltage of DC microgrid. In this paper, a virtual DC machine (VDCM) control strategy of energy storage converter in DC microgrid is adopted, aiming to solve the problem that the DC bus voltage is easy to be disturbed and cannot be well maintained. This control method simulates the characteristics of the DC machine and is a robust and flexible DC/DC converter control method, which can make the converter and the DC bus flexible connection, effectively restrain the DC bus voltage disturbance impact so as to enhance the stability of DC microgrid. A simulation model of DC microgrid with photovoltaic, energy storage device and load is established in MATLAB/Simulink. Simulation results show the feasibility and validity of the adopted control method.

16:20 Stray Capacitance of HVDC Key Devices and Its Impact on Harmonic Distribution

Yunchao Wang (Tsinghua University, P.R. China); Zhanqing Yu (Tsinghua University, P.R. China); Xiao Zhang (Tsinghua University, P.R. China); Jun Hu (Tsinghua, P.R. China); Jinliang He (Tsinghua University, P.R. China); Shuiming Chen (Tsinghua University, P.R. China)

This paper focuses on the stray capacitance of HVDC key devices and its impact on the harmonic distribution and the problem of obtaining wide band models for electrical power system transient simulation purposes for EMTP with linear components. Smoothing reactor, converter transformer and the valve hall can be modeled with stray parameters by segmented wide-band model with skin effect resistance. The simulation curve of the model can already be consistent with measured curves, and it can reflect the resonance characteristics under 100 kHz and fit the stray capacitance well in high frequency. The analysis of overvoltage fault proves that the stray capacitance played an important role in fault analysis with respect to harmonics distribution of HVDC system and the model with stray parameters has significant value of application.