In order to improve the anti-disturbance performance of permanent magnet synchronous motor (PMSM) servo system, a sliding-mode control strategy using a new reaching law (NRL) is proposed. The NRL incorporates power term and switching gain term of the system state variables into the conventional exponential reaching law (CERL), which can effectively suppress the sliding-mode chattering and increase the convergence rate of system state reaching sliding-mode surface. Based on this new reaching law, a sliding-mode speed controller (SMSC) of PMSM is designed. At the same time, to solve the chattering problem caused by the large sliding-mode switching gain, an anti-disturbance sliding-mode speed controller method with an extended sliding-mode disturbance observer (ESMDO), called SMSC+ESMDO method, is developed. The sliding-mode disturbance observer is designed to accurately estimate the motor speed and external load disturbances, and the disturbance estimator is used as a feedforward to compensate the sliding-mode speed controller (SMSC) to improve the system robustness and reduce the system chattering. Simulation and experimental results show that the proposed compound sliding-mode control strategy can effectively improve the dynamic performance and robustness of the system compared with the PI controller.

The grading capacitor is a conventional method to guarantee the uniform voltage distribution (VD) of double-break vacuum circuit breakers (VCBs). However, the main shield voltage unevenness problem of each vacuum interrupter drew little attention in previous study. This article focused on the voltage sharing of the main shield and designed a novel grading capacitor pattern. A dynamic charge compensation (DCC) theory was proposed, which was derived from the novel grading capacitor pattern. Subsequently, an equivalent circuit model, which contained the influence of the DCC, was established for dynamic VD of double-break VCBs. The tests were performed in a synthetic test circuit, and VDs with different grading capacitors patterns were compared, respectively. The results showed that the novel grading capacitor pattern could not only improve the main shield VD but also enhance the effect of balancing the VD ratio between interrupters. The images of cathode spots extinction process correlated the initial condition with postarc sheath growth process. With 83-pF grading capacitors, the compensation effect could reach nearly 50%. Theoretical analysis and test results show the feasibility of the novel grading capacitors pattern, which provides a candidate to put VCBs toward transmission voltage.

Supra electroporation, also known as nanoelectroporation, induced by nanosecond pulse could increase organelle membrane permeability with negligible effect on cell membrane, which has been used for tumor treatment through immunogenic cell death. In order to investigate the supra electroporation of organelle membrane, this study proposes a new topology to generate high voltage pulse with few nanoseconds. This circuit topology contains two main stages: firstly, the topology of diode opening switch (DOS) with LC resonance boosting is used to generate few nanoseconds pulse. Secondly, for improving the output/input voltage gain, four DOS modules are optimally connected (two modules in parallel and another two modules in series) using linear transformer driver (LTD) structure. Moreover, the turn-ON time of MOSFET switch and the inductance of LTD windings are optimized to further boost the voltage amplitude. Finally, experimental results validate the functionality of the proposed topology. The output/input voltage gain can reach 24. This generator can output the nanosecond pulses with full width half maximum (FWHM) of 5.1 ns, amplitude of 3.7 kV (input voltage is 0.15 kV), and repetition frequency up to MHz with unipolar and bipolar polarity in burst mode.