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In this paper, a small-signal model for peak current mode controlled forward converter is proposed to analyze the effect of the magnetizing inductor on the stability of the circuit. From the current loop of the proposed small-signal equivalent circuit, it can be found that the magnetizing current has the same effect of preventing the converter from sub-harmonic oscillation as that of an external ramp. In addition, the feedforward gain of the circuit has been modified due to the effect of the magnetizing inductor. However, the difference between the effect of the magnetizing inductor and that of an external ramp can be found from the derived audio-susceptibility transfer function. The experimental results based on the laboratory prototypes are presented to verify the effects of the magnetizing inductor to the circuit performance.

This study presents a systematic multi-loop block diagrams for the peak current-mode controlled boost converter in order to investigate its intrinsic properties. Under low frequencies, the proposed block diagram of control-to-output can approximate the current loop of the converter to a current source. Furthermore, the block diagram of line-to-output clearly shows three forward paths affecting the AC voltage output. These block diagrams also make it possible to derive the control-to-output and line-to-output transfer functions. Finally, an actual boost circuit is provided and tested. From the experimental and simulation results, the proposed transfer functions are verified.

This experiment designed and fabricated the controller of a brushless DC motor which equips with Hall sensors. The motor driver was fabricated with Microchip dsPIC30F4011 chip which read feedback signals from the Hall sensors. The chip connected to the three-phase six-arm switching inverter circuit then connected to the motor. In such a way the user can drive the motor by position control using the method of six-step square wave vector control. But this conventional control method can just reach a torque of 60 degree power angle. In this study the vector synthesis method was employed to produce a maximum torque of 90 degree power angle. This method can decrease the kinetic energy loss of torque. From the experimental results, it is found that with 90 degree power angle the motor power consumption decreased, torque enhanced and rotation speed increased when compared with 60 degree power angle.

We dissolved hole transport materials α-NPD and NPB in THF solvent, and spin-coated the α-NPD + THF or NPB + THF solution onto ITO anode surface to improve the luminance efficiency and lifetime of flexible fluorescent and phosphorescent organic light emitting diodes. Then the BCP and TPBi were employed as hole blocking layer (HBL) of phosphorescent device and its thickness was optimized. From the experimental results, the maximum luminance efficiency is 4.4 cd/A at 9 V of fluorescent device and 24.4 cd/A of phosphorescent device, respectively. Such an improvement in the device performance was attributed to the smoother surface and good contact between the interface of spin-coated HTL/ITO, the hole were effectively injected from the anode into the organic layer. And the deposited HTL can block excitons from diffusing into the anode to quench, thus improving the luminance efficiency and lifetime greatly.

The small‐signal model for a forward converter with current‐mode control is derived which includes the magnetizing inductance of the main power transformer. It is found that the feedforward gain is modified by magnetizing inductance and so are the transfer functions of current loop gain, control to output and audio susceptibility. Simulation and experimental results show that the effect of the magnetizing inductance is similar to an external ramp which can stabilize the converter system.

The organic light emitting diodes (OLEDs) [1] is a new-generation flat panel display with the advantages of self-luminescence, wide viewing angle (> 160°), prompt response time (~1 μs), low operating voltage (3~10 V), high luminance efficiency, high color purity, and easy to be made on various substrates. Therefore, it’s an important topic that how to improve the luminance efficiency, lifetime and the adhesion characters of ITO/organic interface of flexible OLEDs. Zugang Liu et al. reported that the NPB (HTL) is suitable in contact with the emission layer and when they form an energy ladder structure, the driving voltage decreased and the electroluminescent output increased [2]. Thus it can be seen, the hole transport layer [3-6] is very important to balance the injection of hole and electron, to increase the luminance efficiency and lifetime. In recent years, the hole buffer layer of device typically employs LiF [7], CuPc [8], Pani:PSS [9-10] or PEDOT:PSS [9-11] to improve the hole injection efficiency. In addition, a flexible substrate (PET, metal foil, etc.) surface is not completely smooth and will usually have spikes. After the organic thin film evaporates onto the ITO substrate surface the spikes will still exist. When the device is operated under high voltage or high current density, a heavy amount of electric current will concentrate at the spikes and damage the device by causing the device to short circuit, creating Joule heat. The luminance efficiency of the device will therefore be reduced producing shorter device lifetime. Thus, the PEDOT:PSS fabrication process uses spin-coating to obtain a thin film with a smoother surface than that produced by thermal deposition. Spin-coating enhances the organic material adhesion in subsequent processes, thereby directly affecting the performance of flexible OLED. For the above reason, this research dissolved hole transport material N,N’-diphenyl-N,N’-bis(1-naphthyl)1,1’biphenyl-4,4’’diamine (α-NPD), N,N’Bis(naphthalenel-yl) -N,N’-bis(phenyl)-benzidine (NPB) or α-NPD:NPB in tetrahydrfuran (THF) solvent and spin-coated the buffer layer onto ITO surface of flexible OLEDs. Phosphorescent dye gains energy from the radiative recombination of both singlet and triplet excitons [12], improving the internal quantum efficiency of fluorescent OLEDs (FOLEDs) typically 25% at maximum to nearly 100% [13]. Enhancing the luminance 8

This paper describes a method to improve the production rate for a magnetizer machine by modifying its circuit configurations. A resistor was put in series with the recovery diode in order to bring out part of the heat from the magnetizing fixture. It also reduces the discharging time of the inductor. The branch of the recovery diode in series with the added resistor was moved so that they were in parallel with the discharging capacitor instead of parallel with the magnetizing fixture. It provides a discharging route for the capacitor which was charged reversely when the inductor was discharging.