Search

This work aims to describe the development of a prototype laser diode system along with its driver circuit and a stable microcontroller-based thermoelectric cooling system. The laser diode driver circuit was designed and simulated by using NI Multisim. The driver circuit was built using two LM317 ICs to control the voltage across the laser diode and current through the laser diode. The laser diode output power varies by varying the current across the laser diode through the driver circuit. The temperature of the laser diode rises with time, affecting the output power of the laser diode during a long period of operation. A microcontroller-based cooling system was designed and fabricated using thermoelectric coolers. The microcontroller controls the cooling system ON/OFF period to maintain the laser diode at a particular temperature by removing the excess heat produced during the lasing action. The laser diode with a microcontroller-based cooling system shows that the laser diode output power remains stable during a long period of operation. [ABSTRACT FROM AUTHOR]

This paper describes the development of a Mobile Industry Processor Interface (MIPI) C-PHY transmitter (TX) fabricated using a 28-nm CMOS process with a 1 V supply. In its operational mode, the TX effectively converted parallel signals into low-voltage and high-speed tri-level signals, facilitating seamless serial data transmission. A key aspect of the proposed TX design was the integration of an equalizer (TxEQ) capable of implementing de-emphasis to mitigate channel-induced inter-symbol interference, thereby ensuring robust high-speed data transmission. Furthermore, the output driver was meticulously designed with an optimized structure to ensure impedance matching in different operating modes. Remarkably, the introduction of a boosting pre-driver further enhanced the driving capability, operating independently from the TxEQ of the output driver. Each lane occupied an area of 0.284 mm2, accommodating necessary components such as a pseudo-random bit sequence for random data generation. By employing a boosting technique, the TX achieved a commendable power efficiency of 1.21 mW/Gbps/lane while simultaneously delivering a remarkable 0.52 UI eye-opening at a data transfer rate of 4.56 Gbps/lane.

This paper presents a lifetime optimization of optical sensing system that integrates highly reliable optical sensors and driver circuits that use hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) to realize binary detection of optical signal with a multi-position sensing function for use in large active-matrix liquid crystal display (AMLCD). The optical sensor suppresses the effect of variations in ambient white light using a white-light photocurrent gating (WPCG) structure and increases the reliability of two photo TFTs by halving the drain-to-source voltage (VDS) stress. The driver circuit switches two driving TFTs between their two modes to recover the threshold voltage (VTH) shifts during a long sensing period or generate an output waveform with a large pulse width for driving the optical sensor. Experimental results indicate that the degradation of the photocurrent of the photo TFT is suppressed from 3.71 nA to 1.03 nA, representing an improvement of 72.2% relative to the original WPCG structure. The minimum difference between the output voltages of the optical sensing systems with and without an optical signal under illumination by ambient white light from 500 to 10000 lux is 18.58 V. According to an accelerated lifetime test, the feasibility of using the optical sensing system in large AMLCDs is verified.

Frequency tracking and amplitude control are essential for piezoelectric transducers. Frequency tracking ensures the piezoelectric transducer operates at the resonant frequency for maximum power output, and amplitude control regulates the mechanical motion of the output. This paper presents a novel driver based on a push–pull inverter for piezoelectric transducers. The proposed driver realizes the frequency tracking and amplitude control scheme by a voltage sensing bridge in the case of transformer secondary matching, guaranteeing automatic frequency tracking and precise mechanical functions regardless of environmental and load variations. The proposed scheme is verified by the ultrasonic scalpel and the ultrasonic motor (USM). The experimental results show that this scheme reduces the build-up time from 10 ms to 3 ms and loaded frequency variations from 250 Hz to 200 Hz. In addition, the amplitude control performance was further observed on USM for various loads. The overshoot is less than 5.4% under different load torques. Therefore, the proposed scheme improves the load adaptability and stability of piezoelectric transducers and promotes the application of piezoelectric transducers under various conditions. [ABSTRACT FROM AUTHOR]

With the global advocacy of green lighting and the urgent need for energy saving and carbon reduction, more and more street lighting applications have entered the era of being replaced by light-emitting diode (LED) lighting sources. This paper presents a new LED streetlight driving circuit applied to a direct current (DC)-input voltage source, which consists of a buck converter combined with a flyback converter to reduce the number of circuit components required and to recover the leakage energy of the transformer to improve energy conversion efficiency. In addition, this study also completed the analysis of the operational principle of the new LED streetlight driving circuit, and developed a prototype LED streetlight driver with DC-input voltage of 48V and output power of 72 W (36 V/2 A). Finally, the measurement results of the prototype circuit show that the output voltage ripple rate was less than 15%, the output current ripple rate was less than 6%, and the circuit efficiency was as high as 91%. [ABSTRACT FROM AUTHOR]

In recent years, electric vehicles are the large-scale spread of the transportation field has led to the emergence of brushless direct current (DC) motors (BLDCM), which are mostly utilized in electrical vehicle systems. The speed control of a BLDCM is a subsystem, consisting of torque, flux hysteresis comparators, and appropriate switching logic of an inverter. Due to the sudden load torque variation and improper switching pulse, the speed of the BLDCM is not maintained properly. In recent research, the BLDC current control method gives a better way to control the speed of the motor. Also, the rotor position information should be the need for feedback control of the power electronic converters to varying the appropriate pulse width modulation (PWM) of the inverter. The proposed optimization work controls the switching device to manage the power supply BLDCM. In this proposed self-ameliorate soft switching (SASS) system is a simple and effective way for BLDC motor current control technology, a proposed control strategy is intended to stabilize the speed of the BLDCM at different load torque conditions. The proposed SASS system method is analyzing hall-based sensor values continuously. The suggested model is simulated using the MATLAB Simulink tool, and the results reveal that the maximum steady-state error value achieved is 4.2, as well as a speedy recovery of the BLDCM's speed. [ABSTRACT FROM AUTHOR]

Gate driver circuits to ensure proper turn-on and turn-off for power switches are essential parts of a power converter design. They become significantly challenging for multilevel converters, where multiple switches are operated at active voltage domains. The recent favorable use of gallium nitride devices for power switches makes gate driving even more difficult as the switch performance and reliability are very sensitive to the variations of the gate driving signals and power rails compared with traditional power MOSFETs. This article discusses gate driving methods using a multilevel multi-inductor hybrid (MIH) converter as the demonstration prototype to address two key challenges in designing gate drivers: 1) providing level-shifted pulsewidth modulation signals to active voltage domains and 2) powering schemes for gate driver circuits. To solve the first challenge, an optimal use of available half-bridge drivers is proposed to eliminate the need for separate signal isolator chips. This method was implemented and verified in an MIH converter prototype for 48-V point-of-load applications using three different powering schemes for gate drivers, including isolated power modules, regulated supplies from switch blocking voltages, and cascaded bootstrap power rails with regulations. The gate driver techniques and powering schemes are compared experimentally in terms of performance to illustrate their benefits and tradeoffs. [ABSTRACT FROM AUTHOR]

Frequency tracking and amplitude control are essential for piezoelectric transducers. Frequency tracking ensures the piezoelectric transducer operates at the resonant frequency for maximum power output, and amplitude control regulates the mechanical motion of the output. This paper presents a novel driver based on a push–pull inverter for piezoelectric transducers. The proposed driver realizes the frequency tracking and amplitude control scheme by a voltage sensing bridge in the case of transformer secondary matching, guaranteeing automatic frequency tracking and precise mechanical functions regardless of environmental and load variations. The proposed scheme is verified by the ultrasonic scalpel and the ultrasonic motor (USM). The experimental results show that this scheme reduces the build-up time from 10 ms to 3 ms and loaded frequency variations from 250 Hz to 200 Hz. In addition, the amplitude control performance was further observed on USM for various loads. The overshoot is less than 5.4% under different load torques. Therefore, the proposed scheme improves the load adaptability and stability of piezoelectric transducers and promotes the application of piezoelectric transducers under various conditions.

Position sensing is one of the crucial parts of the active magnetic bearing (AMB) system. The printed circuit board (PCB) eddy current position sensor is a new type of position sensor for the AMB system, which makes a compact structure, high sensing quality, and is low cost. In this article, an improved driver circuit is proposed for this new sensor. The driver circuit includes an excitation circuit and signal conditioning circuits. A crystal oscillator circuit with a power stage is used to provide the excitation coil with a stable excitation source of high stability and good precision of frequency. The analog demodulation circuit is designed for signal conditioning circuits to extract the rotor displacement information from the sensing coil outputs. Compared with the state-of-art driver schemes, the proposed method reduces the circuit complexity and cost. Accordingly, the experimental results show that the designed sensor has good linearity and sensitivity, and it can ensure AMB stable operation at the rated speed. [ABSTRACT FROM AUTHOR]

Many examples of capacitorless and inductorless drivers used to power LED lamps directly from the AC mains use complicated circuitry in the form of a dedicated integrated circuit which is designed for a particular multistring lamp in order to obtain the value of the power factor very close to 1 and high efficiency of the whole unit. However, the authors of such descriptions do not provide any details concerning the optimum choice of the number of strings in a LED lamp and the number of LEDs in each string. The aim of this work is to show that acceptable values of both electrical parameters mentioned above can be obtained using a LED lamp with just one or two strings. Some formulae and results of their numerical analysis for the 230 V 50 Hz mains are presented, thanks to which designers of LED lamps and their AC direct drivers may easily estimate the optimum conduction voltage of a LED string or the number of single LEDs in a string.

Displacement sensor is the key component of the magnetic levitation system. Reducing complexity and improving reliability of the sensor circuits are very important to mass production of magnetic levitation devices. In this article, an improved driver circuit of eddy current sensor is proposed. In order to generate a stable oscillating source with high stability and good precision of frequency, a crystal oscillator circuit with power boost is used to replace the traditional Colpitts oscillator circuit. The improved modulation circuit is composed of passive components with a simple structure for improving reliability. The parameters design method of the modulation circuit is analyzed in detail, which greatly affects the sensitivity and linearity of the sensor. The experimental results show that the designed eddy current sensor has good linearity (1.12%) and sensitivity (2.14 V/mm), and it can ensure the stable operation of the magnetic levitated turbomolecular pump at the rated speed. [ABSTRACT FROM AUTHOR]

Theoretically, normally‐off silicon carbide (SiC) junction field‐effect transistors (JFETs) do not require a negative gate voltage supply because they are in an off‐state when the gate–source voltage is 0 V. However, most gate drivers for normally‐off SiC JFETs require not only a positive power supply for turning on the JFET but also a negative power supply for turning it off and maintaining a negative gate–source voltage to suppress a false turn‐on power loss caused by crosstalk during fast switching. Therefore, modifications of gate drivers increase complications and costs. In this study, a normally‐off SiC JFET gate driver, which can be realized using a simple circuit configuration with a single power supply, is proposed. To minimize undesirable crosstalk, the gate‐source voltage of the JFET is driven to a negative value and retained in the state for a long period of time. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

When using a high-resolution full-frame area array charge-coupled device (CCD) FTF4052M as the aerial image sensor of a camera, the frame rate is generally below 1 frame/second (fps), which cannot meet the requirements of applications with high frame rates. First, the FTF4052M drive circuit is introduced. Next, an improved driver circuit of the CCD 4052M is proposed. Using the CCD to output four amplifiers simultaneously yielded a maximum frame rate of 3.4 fps. Then, the timing of the CCD driver, the front-end processing circuit, the DC bias circuit, and the interface circuit of the four outputs are designed. The improved driver circuit could meet the application requirements of various aerial cameras. In addition, the FTF4052M nonuniformity is analyzed, and a nonuniformity response detection system is established. Using this system, the FTF4052M array's nonuniformity among the four quadrants and among the pixels is tested. Based on the CCD's linear responsivity, two correction algorithms are proposed to correct the nonuniformity. Finally, using the correction, the four quadrants' standard deviations of the response sensitivity are reduced by a factor of 1/13, and the responsive nonuniformity among all pixels is reduced by a factor of 1/10. Through the reshooting of the identified rate board, it is found that the nonuniformity of the CCD array is markedly improved. [ABSTRACT FROM AUTHOR]

The semiconductor laser diode SPL LL90_3, which integrates the RC charge‐discharge circuit and a MOSFET switching device, is usually used for pulsing laser in the light detection and ranging system with a rated peak power of 70 W at 30 ns pulse‐width. To further increase the peak power and reduce the pulse width and rising edge, a driving circuit with an avalanche transistor used as a pre‐switching device is proposed. A trigger pulse with about 10 ns'‐pulse‐width is obtained to drive the laser diode. At the same time, the pulsing laser's peak power can reach 141 W at the testing repetition rate of 55 kHz. [ABSTRACT FROM AUTHOR]

Many examples of capacitorless and inductorless drivers used to power LED lamps directly from the AC mains use complicated circuitry in the form of a dedicated integrated circuit which is designed for a particular multistring lamp in order to obtain the value of the power factor very close to 1 and high efficiency of the whole unit. However, the authors of such descriptions do not provide any details concerning the optimum choice of the number of strings in a LED lamp and the number of LEDs in each string. The aim of this work is to show that acceptable values of both electrical parameters mentioned above can be obtained using a LED lamp with just one or two strings. Some formulae and results of their numerical analysis for the 230 V 50 Hz mains are presented, thanks to which designers of LED lamps and their AC direct drivers may easily estimate the optimum conduction voltage of a LED string or the number of single LEDs in a string. [ABSTRACT FROM AUTHOR]

Dispersed‐type inorganic electroluminescent (EL) devices composed of a transparent electrode, a phosphor, a dielectric, and a back electrode were prepared under various conditions using a zinc sulfide (ZnS)‐based phosphor. Additionally, a voltage/frequency variable circuit was designed. A compact high‐voltage/frequency variable circuit including three modules for boosting, frequency conversion, and voltage conversion was designed. A 140 Vpp voltage and a frequency in the range of 270 Hz to 2.4 kHz can be controlled by this circuit. The emission has begun to be observed at a voltage about 60 Vpp and a frequency of 400 Hz, at a voltage about 40 Vpp and a frequency of 1.4 kHz, 2.4 kHz, respectively. The emission intensity increased with an increase in frequency; emission with a wavelength of 450 nm was strongly influenced by the frequency. The luminescence and the electrical properties were affected by the preparation conditions including device structures, dispersion of ZnS:Cu, and Cl particles because of the current path generated by defects in the EL cell. Dispersed‐type inorganic electroluminescent devices were prepared under various conditions using a zinc sulfide‐based phosphor including organic dye. Additionally, a compact voltage/frequency variable circuit was designed. The driving characteristics were systematically investigated including their luminescence and electrical properties. [ABSTRACT FROM AUTHOR]

This paper presents a novel single-channel IGBT driver circuit together with a procedure for testing and verification. It is based on a specialized integrated circuit with complete range of protective functions. Experiments are performed to test and verify its behaviour. Experimental results are presented in the form of oscilloscope recordings. It is concluded that the new driver circuit is compatible with modern IGBT transistors and power converter demands and that it can be applied in new designs. It is a part of new 20kW industrial-grade boost converter.

Piezoelectric actuation is a promising principle for insect-scaled robots. A major concern while utilizing a piezoelectric actuator is energy loss due to its parasitic capacitance. In this paper, we propose a new concept to recover the charge stored in the parasitic capacitance; it requires only three additional lightweight passive components: two diodes and a resistor. The advantages of our concept are its small additional mass and simple operating procedure compared with existing charge recovery circuits. We provided a guideline for selecting a resistor using a simplified theoretical model and found that half of the charge can be recovered by employing a resistor that has a resistance sufficiently larger than the forward resistance of the additional diode. In addition, we experimentally demonstrated the concept. With a capacitive load (as a replacement for the piezoelectric actuator), it was successfully observed that the proposed concept decreased the power consumption to 58% of that in a circuit without charge recovery. Considering micro aerial vehicle (MAV) applications, we measured the lift-to-power efficiency of a flapping wing piezoelectric actuator by applying the proposed concept. The lift force was not affected by charge recovery; however, the power consumption was reduced. As a result, the efficiency was improved to 30.0%. We expect that the proposed circuit will contribute to the advancement of energy-saving microrobotics.

This paper presents a high-efficiency compensation method of the dead zone with the aid of the adaptive dither for the ultrasonic motor. Prior to proposing the method, the influence of the dither on the principal elements of the dead zone, i.e., the deviations of the control variable and the minimum velocity, is analyzed. Then, the improved generation method of the adaptive dither is proposed, which introduces the adaptive dither by orthogonally adjusting the amplitudes of the applied voltages instead of changing the phase difference, as mentioned in the existing studies. Experimental measurements have demonstrated that the proposed method not only can effectively compensate the dead zone and conveniently control the velocity, but also is superior to the existing phase-difference-based method in terms of improving the efficiency of the ultrasonic motor. [ABSTRACT FROM PUBLISHER]

Based on the Z‐source inverter (ZSI), a unified control strategy of grid‐connected photovoltaic (PV) system is investigated. It can both compensate the reactive power and restrain the current harmonics. At first, the principle of the proposed unified control is analysed. Then, the space vector pulse width modulation (SVPWM) is improved for inserting the shoot‐through time into the modulation period. Simulation results show that the proposed unified control strategy is feasible and effective. Besides, a hardware controller is designed based on the digital signal processor (DSP). The corresponding approach for applying the improved SVPWM with the DSP and the driver circuit is illustrated in detail. Eventually, an experiment apparatus is implemented. Experiment results reveal that the proposed unified control strategy can effectively regulate active and reactive power generated by the grid‐connected PV system. Besides, the fifth current harmonic of grid can be restrained effectively, the total harmonic distortion of the grid current decreases from 20.9 to 8.1%, which indicates that the restraint of the current harmonics is feasible for the proposed unified control strategy. [ABSTRACT FROM AUTHOR]