Hao Minghui

A harmonic injection SPWM method for the high-responsive PMSM control system

In a permanent magnet synchronous motor (PMSM) control system, usually, the phase voltage instruction is limited independently to prevent a three-phase pulse width modulation (PWM) wave from overflowing. This method decreases the efficiency of the bus voltage and causes voltage vector direction errors. To solve these problems, we propose a harmonic injection sinusoidal pulse-width modulation (SPWM). This method uses harmonic injected sinusoidal PWM to improve the utilisation ratio of the bus voltage, and consequently improve system performance. In this paper, we analyse the problem in terms of potential difference. The simulation results show that the proposed method can increase the utilisation ratio of the bus voltage up to 15.4%, and the voltage vector mode obtained with the proposed algorithm is larger than that obtained with the conventional one. The method with harmonic injection consequently improves current response, without affecting voltage vector accuracy. The experiment results validate the proposed method.

Development of 3D sound simulation system for flight simulator

For the purpose of acquiring the immersion and reality of flight simulation, there is a necessity to reproduce 3D sound field of aircraft cockpit. In this paper, a 3D sound simulation system which is integrated into flight simulator used for training pilots is developed. After determining the sound events which will be simulated in flight simulation, spectrum analysis and time-frequency analysis are used to analyze original recordings for finding out the sound features of each part of an aircraft. And then sound sources which will be used in simulation can be extracted by using LMS adaptive filtering and other basic signal processing methods. Based on system integration and performance consideration, a new component of sound simulation system is presented and the object-oriented software development is used to develop the software part for matching this component. Two key technologies are particularly discussed in software realization: real-time sound synthesis and sound spatialization. The 3D sound simulation system meets development requirements after many flight tests and works reliably in a Boeing 737-800 flight simulator which is developed in our lab.

A 3D Sound Simulation System for Flight Simulator

A realistic 3D sound simulation system which is integrated in a flight simulator used for training of pilots is developed. The components of a flight simulator are introduced briefly. To meet the requirements of sound simulation system, Visual C++ and DirectSound API are selected as development software. We discuss the design and implementation of a sound simulation system by using DirectSound. The key technologies in development which include sound source analysis and sound spatialization are analyzed. Sound spatialization (3D sound) technology is especially discussed and is solved by using DirectSound 3D in development. The 3D sound simulation system meets all development requirements and works reliably in a Boeing 737-800 flight simulator which is developed in our lab.

Theory Research on NC Instruction Interpretation for Trajectory Trace

Based on the global optimization design method of Mechatronics, from the perspective of the performance optimization of the overall CNC equipment, the dynamic model of the controlled mechanism is built, and then which is used to research on the error-free trajectory tracking for the controlled mechanism. Based on the model of the error-free trajectory tracking, NC instruction interpretation with high-order differentiability is proposed, and then relevant in-depth research is performed. NC instruction interpretation with high-order differentiability is pointed out. Finally, it is achieved on the multi-axis system with the same cycle control has been successfully developed by the author. The result demonstrates that NC instruction interpretation with high-order differentiability is useful to improve the error of trajectory tracking.