The commercial mature gallium nitride high electron mobility transistors (GaN HEMT) technology has drawn much attention for its great potential in industrial power electronic applications. GaN HEMT is known for low on-state resistance, high withstand voltage, and high switching frequency. This paper presents comparative experimental evaluations of GaN HEMT and conventional Si insulated gate bipolar transistors (Si IGBTs) of similar power rating. The comparative study is carried out on both the element and converter level. Firstly, on the discrete element level, the steady and dynamic characteristics of GaN HEMT are compared with Si-IGBT, including forward and reverse conducting character, and switching time. Then, the elemental switching losses are analyzed based on measured data. Finally, on a complementary buck converter level, the overall efficiency and EMI-related common-mode currents are compared. For the tested conditions, it is found that the GaN HEMT switching loss is much less than for the same power class IGBT. However, it is worth noting that special attention should be paid to reverse conduction losses in the PWM dead time (or dead band) of complementary-modulated converter legs. When migrating from IGBT to GaN, choosing a dead-time and negative gate drive voltage in conventional IGBT manner can make GaN reverse conducting losses high. It is suggested to use 0 V turn-off gate voltage and minimize the GaN dead time in order to make full use of the GaN advantages.

No abstract

No abstract

No abstract

Quick convergence, simple implementation, and accurate estimation are essential features of realizing permanent-magnet synchronous motor (PMSM) position estimation for sensorless control using microcontrollers. A linear observer is often designed on real plant variables and is more sensitive to parameter uncertainty/variations. Thus, conventionally, a sliding mode observer (SMO)-based technique is widely used for its simplicity and convergence ability against parameter uncertainty. Although SMO has been improved for switching chattering and phase delay, it provides purely proportional gain, which leads to steady-state error and chattering in observation results. Different from conventional linear observer using real plant variables or SMO with proportional gain, a simple proportional-integral linear observer (PILO) using virtual variables is proposed in this paper. This paper also provides a comparative study with SMO. By introducing virtual variables without physical meaning, the PILO is able to simplify observer relations, get smaller phase shifts, adapt mismatched parameters, and obtain a fixed phase-shift relation. The PILO is not only simple, but also improves the estimation precision by solving the controversy between chattering and phase-delay, steady-state error. Moreover, the PILO is less sensitive to parameters mismatching. Simulation and experimental results indicate the merits of the PILO technique.

This paper presents a fault tolerant control strategy for six-phase transverse flux tubular PMLM based on Synthetic Vector Method when the machine has a single phase open circuit fault. The operation of six-phase transverse flux tubular PMLM is described as well as its basic mathematical model. Then, the principles of Synthetic Vector Method are introduced. Based on these theories, the fault tolerant control strategy is derived in detail under the single phase open fault condition. In addition, a fault tolerant, dual Three-phase Four-leg Inverters drive topology which can be applied under this faulted condition is proposed. More, to implement the control algorithms proposed, a modified Space Vector Modulation is presented. Both the finite element simulation and the MATLAB/Simulink simulation results illustrate the validity of proposed fault tolerant control as well as the associated control topology and space vector modulation.Index Terms-Six-phase transverse flux tubular PMLM, fault tolerant control, single phase open circuit, dual Three-phase Four-leg Inverters drive NOMENCLATURE U s Stator voltage vector, U s = [u a1 u b1 u c1 u a2 u b2 u c2 ] T I s Phase current vector, I s = [i a1 i b1 i c1 i a2 i b2 i c2 ] T E a Back EMF vector, E a = [e a1 e b1 e c1 e a2 e b2 e c2 ] T R s Stator resistance matrix L s Phase self-inductance matrix ψ m Fundamental amplitude of phase flux linkage τ Pole pitch ν Speed of the mover, ν = 2τf x Position of the mover, x = ν/t Subscripts a, b, c Phase quantities α, β Stationary frame quantities d, q Synchronous rotating frame quantities

No abstract

No abstract