Wang Chenchen

Study on a hybrid PWM method under low switching frequency

This paper presents a hybrid PWM method under a low switching frequency based on SVPWM and SHEPWM, which use asynchronous carrier modulation SVPWM at low frequency, and SHEPWM at high frequency, a square wave after rated conditions. The transitive strategy is proposed to realize smooth transition of individual modes including SVPWM, SHEPWM and square wave. Simulation and experimental results confirm this hybrid modulation method and their transition is reasonable and corrected.

An improved voltage balancing compensator for three-level NPC converters

Neutral-point potential oscillation and balancing problem is an inherent drawback hindering the extensively application of Neutral-Point-Clamped three-level converters. Based on the excellent performances of double signal PWM method contributing to the oscillation elimination, this paper proposes an improved neutral-point voltage balancing compensator. The validity and practicability of the proposed algorithm is verified by simulation and experimental results.

An equivalent dual three-phase SVPWM realization of the modified 24-sector SVPWM strategy for asymmetrical dual stator induction machine

A modified space vector pulse width modulation (SVPWM) strategy based on vector space decomposition and its equivalent dual three-phase SVPWM realization are proposed in this paper, which is suitable for two-level six-phase voltage inverter fed asymmetrical dual stator induction machines (DSIMs). The DSIM is composed of two sets of symmetrical three-phase stator windings spatially shifted by 30 electrical degrees. The proposed SVPWM technique can reduce the torque ripple and suppress the harmonic currents flowing in stator windings. Above all, the equivalent relationship between the proposed SVPWM technique and the dual three-phase SVPWM technique has been demonstrated, which allows easy implementation for digital signal processor (DSP). Simulation and experimental results, carried out separately on a simulation system and a 3.0 kW DSIM prototype test bench, are presented and discussed.

Current Situation and Countermeasures of Multinational Mergers and Acquisitions in China

In the context of accelerating economic globalization, international trade and investment are scaling up. Transnational merger and acquisition has already has great influence on our economy. So based on the status and characteristics of the expansion of transnational corporations in China, this essay analyzes the causes and influences of transnational merger and acquisition, and how economic globalization creates opportunities and challenges for China, aiming to maintain economic security and sustainable development by proposing strategies to deal with transnational merger and acquisition.

Design and analysis of a decoupling current controller for induction machine

This paper analyzes the characteristics of current controllers for vector-controlled AC motors. In synchronous reference frame, the existence of cross-coupling, which increases with the synchronous frequency, impairs the behavior of torque response. System vibration and instability can occur if the current controller does not properly compensate the coupling and delays between the sampling of signals and PWM output. To overcome these problems, a decoupling current control scheme is proposed based on a more accurate induction machine model. The time-delay and corresponding compensation strategy are also studied in this paper. Simulation and experimental results are provided to show the improved dynamic performance of the proposed current controller.