No abstract

Designing the dq-frame current regulator for single-phase voltage-source inverters is a very challenging task. Since only one real current signal exists in the circuit, an orthogonal signal generation (OSG) block is required to generate the virtual orthogonal signal. Thus, ac variables can be turned into equivalent dc quantities through an αβ/dq transformation. However, the OSG block makes the control system complex and introduces an extra transient disturbance. Consequently, the dynamic performance is deteriorated. In this study, the reference-current-based OSG method is analysed thoroughly. Based on this structure, the dq-axes decoupling control, which is widely discussed for three-phase systems and usually neglected for singlephase systems, is studied. Two decoupling techniques, i.e. the reference-current feed-forward control and the quasi-complex vector proportional-integrator control, are implemented and analysed. The proposed theories and control schemes are evaluated by experimental results.

In this paper, a simple and practical design method of electric engineering maintenance rolling stock (EEMRS) is briefly presented, which is composed of six power units. It is important to improve the energy conservation and efficiency of power converters and reduce the size of the heat dissipation system for EEMRS. Therefore, loss analysis of power semiconductors is very necessary. A new modulating function is proposed on the basis of vector modulation, and the instantaneous power losses and the average conduction power losses in insulated gate bipolar transistor (IGBT) and free‐wheeling diode (FWD) are deduced from the modulating function. Additionally, considering that the junction temperature oscillates with the output frequency, a simple calculation method of the junction temperature ripple is presented, which is helpful in examining the junction temperature limited to the maximum value. Based on the analysis, a heat dissipation system for the direct/alternating current (DC/AC) inverter using forced‐air cooling is designed, and the calculation results and the experimental results are given, which verify the feasibility of the proposed method. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Abstract:The overall configuration of a magnetic suspension decoupling control system is designed to realize the reliable digital control of a 3-phase bearingless induction motor whose rotor windings are not pole-specific. Based on a digital signal processor complementary metal-oxide semiconductor chip, the digital control hardware and software systems are analyzed and designed. In this paper, the calculation and regulation of the motor rotational speed, correction and regulation methods of the radial displacements, calculation and compensation algorithms of the unilateral magnetic pulls, induction compensation algorithm of the effective suspension control current, current regulation, and space-vector pulse width modulation algorithms, are presented in detail. The experimental results verify the feasibility and practicability of the designed decoupling digital control system of the 3-phase bearingless induction motor.

No abstract

Two-stage single-phase grid-connected converters are widely used in renewable energy applications. Due to the presence of a second harmonic ripple across the DC bus voltage, it is very challenging to design the DC bus voltage control scheme in single-phase grid-connected inverters. The DC bus voltage controller must filter the ripple and balance a tradeoff between low harmonic distortion and high bandwidth. This paper presents a fast DC bus voltage controller, which uses a second order digital finite impulse response (FIR) notch filter in conjunction with input power feedforward scheme to ensure the steady-state and dynamic performance. To gain the input power without extra hardware, a Kalman filter is incorporated to estimate the DC bus input current. At the same time, a modulation compensation strategy is implemented to eliminate the nonlinearity of the grid current control loop, which is caused by the DC bus voltage ripple. Moreover, a novel synchronous frame current controller for single-phase systems is also introduced, and its equivalent model in stationary frame has been derived. Simulation and experimental results are provided to verify the effective of the proposed control scheme.

No abstract

No abstract