Shenghua Huang

General Analytical Models of Inductance Matrices of Four-Pole Bearingless Motors With Two-Pole Controlling Windings

In this paper, after introducing the bearingless motors working principle in brief, we analyze the magnetic field distribution principle of the bearingless motor. We then derive in detail the general analytical models of inductance matrices of a four-pole bearingless motor with two-pole controlling windings. The derived general analytical models are applicable not only to bearingless motors with a salient-pole rotor, but also to bearingless motors with a cylindrical rotor. By setting different values of salient-pole arc width parameter rho in the general models of inductance, the analytical models of inductance of different types of bearingless motors, such as bearingless induction motors, bearingless synchronous reluctance motors, and bearingless surface-mounted permanent magnet (SPM) motors, can be derived.

A control strategy of three-phase voltage-sourced PWM rectifier

The double closed loops control strategy composed of inner current loop and outer voltage loop in the d-q synchronous frame is a relatively common control strategy of the three-phase voltage-sourced PWM rectifier. The system can not be completely decoupled because of the variable inductance in the actual system. And for simple, the decoupled part of the controller is usually ignored. Whats more, the equation of the outer voltage loop is nonlinear. According to the analysis of the model of the rectifier, a novel double closed loops control strategy composed of inner current loop in the complex vector and outer square of the voltage loop, is proposed. The inner current loop using the mentioned control strategy can be completely decoupled without the exact value of the boost inductance, and the equation of the outer square of the voltage loop is linear. From the results of the simulation, the mentioned control strategy can greatly improve the dynamic and static of the system.

Analysis and optimization of a micro SMES system using multiple parallel solenoids

The micro superconducting magnetic energy storage system is becoming a powerful tool for application in power systems. Nowadays, devices include active shielding systems instead of passive ferromagnetic shields. This calls for sophisticated analysis and design techniques able to provide satisfactory performance in terms of stored energy efficiency, reduced stray field, and/or minimal superconductors volume. In this paper, the features of an active shielding system using multiple parallel solenoid configurations for superconducting magnets are analyzed and the results of their corresponding stray fields are compared. Two optimization strategies are briefly presented. The results using the proposed optimization strategies for magnet systems of energy capacity of 1 MJ, 5 MJ, and 10 MJ are given, respectively.

Carrier phase-shifted discontinuous PWM algorithm for cascaded H-bridge inverters

Previous work has shown many general space vector PWM algorithms for cascaded H-bridge inverters. To keep the load balance of switches for cascaded H-bridge inverters, complex pulse cycle control must be added to the algorithms. This paper presents carrier phase-shifted discontinuous PWM (CPS-DPWM) algorithm which can keep load balance of switches automatically. More importantly, switching frequency is reduced up to 2/3 of the previous. Simulation results are given for the verification of CPS-DPWM algorithm.

Direct Active Power Control for Regenerative Cascade Inverter with Reduced AC Power in DC Link

This paper presents a regenerative cascade inverter topology with direct active power control scheme. From the mathematical model of the proposed regenerative cascade inverter, the instantaneous active power and reactive power are derived. Based on the instantaneous abc theory, direct active power feed-forward control is proposed to reduce AC power and voltage fluctuation in DC link. Moreover, a load current full order observer is established to avoid the inconvenient of the current sensor installation. The proposed control scheme is analyzed theoretically by simulation, and verified experimentally.

A comprehensive study of relationship of two simplified space vector modulation methods and the application in three-level inverters

In this paper, two modified space vector pulse width modulation (SVPWM) methods are presented. The relationship of them is comprehensively studied. A variable factor ko is introduced into the unified voltage modulation method. Due to factor ko, the time duration of application of two zero state vectors is made changeable from 0 to 100% over the sampling period for their combined application, which makes the strategy is flexible and universal. Additionally, by introducing factor ko into the unified voltage modulation, it can prove that the two simplified SVPWM schemes are exactly identical. Owing to the variable factor, the two simplified SVPWM methods can be employed to balance the neutral-point potential in the neutral-point-clamped three-level inverter. The proposed modulation technique is verified by experiment.

A simplified DQ-frame current controller for single-phase grid-connected inverters with LCL filters

In dq-frame current control scheme for single-phase grid-connected inverters, an orthogonal signal generation (OSG) block is required to generate a virtual orthogonal signal. The OSG block makes the control system complicated and introduces extra disturbance, which deteriorates the dynamic performance. This paper presents a simplified dq-frame current controller for single-phase grid-connected inverters. A novel OSG method, which does not introduce any additional dynamics or distortions to the control loop, has been discussed. The decoupling control for the dq-axes cross-coupling is analyzed. Moreover, LCL filters are also implemented to improve grid current quality. Simulation shows that the proposed controller has excellent performance.

A Novel Control Strategy for HEV Using Brushless Dual-Mechanical-Port Electrical Machine on Cruising Condition

Brushless Dual-Mechanical-Port Electrical Machine (BLDMPEM) is a new type of motor designed for Hybrid Electric Vehicle (HEV), which contains two mechanical ports and two electric ports. Compared with Dual-Mechanical-Port Electrical Machine (DMPEM), the brushless structure brings higher reliability and easier maintenance. In this paper, the model of BLDMPEM is discussed. In Chapter 2, the energy flow and mathematical model of BLDMPEM are analyzed. Then a novel three-phase half-bridge controlled rectifier topology and its control strategy for cruising mode of HEV based on BLDMPEM are proposed in Chapter 3. Compared with the Field Oriented Control (FOC) strategy of BLDMPEM, the proposed method does not require accurate motor parameters, and it is much simpler and easier to be implemented. At last, simulation and experiment results show the feasibility and validity of the proposed strategy.

A Kind of Generalized Analytical Model on Magnetic Suspension Force of Bearingless Motor and its Application

The generalized Analytical model on inductance of bearingless 4-pole motor with 2-pole suspension windings is given firstly. Then, based on the inductance model, the generalized analytical model on Maxwell magnetic suspension force of 4-pole bearingless motor with 2-pole suspension windings and columnar stator, is analyzed and derived in detail. The generalized model on Maxwell force is not only applicable to bearingless motor with salient-pole rotor, but also applicable to bearingless motor with cylindrical rotor. At the end, by setting relevant pole-width parameter in the generalized model on magnetic suspension force, the magnetic suspension force model of bearingless induction motor is derived; the relevant decoupling control system is devised, and the simulation experiment is made. The simulation results have proved the validity and feasibility of the generalized analytical model. Thus, the theory foundation is made solidly for the further study on fundamental theory and common rules of bearingless motors, and for the further study on dynamic characteristics of bearingless motor.

Analysis and optimized design of magnet for micro SMES with multiple parallel solenoids

In this paper, the features of actively shielding systems, the multiple parallel solenoid configurations, for superconducting magnets are analyzed and the results of their corresponding stray fields are compared. Two optimization strategies are briefly presented. The results using the proposed optimization strategies are given.