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Based on the analysis of constant frequency, periodical frequency-spreading scheme and chaotic frequency-spreading scheme, the article has discussed the mechanics and the characters of the chaotic PWM suppressing EMI in the converter. Experiments have been made on an AC-DC forward converter. The experiment results show that the EMI spectrum is decided completely by the PWM spectrum, and the chaotic frequency-spreading has an obvious impact on EMI suppressing, compared with the other schemes. The frequency character of the ripple has been changed but the peak value and the shape of the ripple have kept almost the same as before, and after the frequency is spread chaotically, the converter system works stable. The article has made up the lack of theory analysis and experiment analysis of chaotic PWM suppressing EMI.

A new gas‐around‐liquid spray nozzle (GLSN) was designed, and the two‐phase flow fluid field in this nozzle was simulated numerically. Flow characteristics under different structural parameters were obtained by changing the L/D ratio of the premixing chamber, incident angle, and inlet pressures. Increasing the L/D ratio and incident angle improved flow characteristics such as atomization flow, outlet velocity, and turbulence intensity. The nozzle performed optimally at an L/D ratio of 0.5 and incident angle of 60°. The atomization flow decreased with higher gas pressure and increased with higher liquid pressure. The outlet velocity mainly depended on the inlet gas pressure, not on the inlet liquid pressure. These results provide an indication for optimum structures and parameters of the GLSN.

Permanent magnet synchronous motors(PMSM) are gradually replacing DC motor in a wide range of drive applications, high performance control demands are being proposed. This paper investigates into various vector control strategies of permanent magnet synchronous motors drive. It also elaborates the concept of its maximum torque control, analyses the relationships between its vector control and maximum torque control under different d and q axes parameters of PMSM, and carries out the operation and realization conditions of its maximum torque control. Some significant theoretical results are obtained.