Based on dual peak resonance of long-period fiber grating(LPFG),a novel film sensor is presented,in which the film that is sensitive to the surrounding gases is coated on the cladding of the fiber grating region,and the intervals of dual peak resonant wavelengths change with the film refractive index.

Taking the injection-type hybrid APF (Active Power Filter) as an example,a synthesized hysteretic control method for current tracking is proposed by establishing its mathematical model,which combines the fast hysteretic control with the zero-static-error double harmonic integrator control.

Design principles of input filter is proposed, which can limit the filter resonant peaking and have good steady filtering effect, and won抰 degrade the stability and the performance against disturbance of DC/DC converter.