A PWM controller for extended temperature applications

In the multi-output high-voltage isolated power supply for solid-state switches, LCL resonant network is used to obtain the constant current source on the bus, and the bus current is independent of the load. Therefore, the secondary side of the toroidal transformer needs to use the current input voltage regulator circuit. When the input is a current source instead of a voltage source, the traditional voltage regulator circuit is no longer applicable. Therefore, this paper focuses on the study of dc voltage regulated circuit with current source input. Compared with the traditional linear regulated power supply, switching power supply has the advantages of high efficiency, large output power, small size, light weight and low cost. In this paper, pulse width modulation (PWM) technology is used to control the switching on and off, and UC3843 is used to design a switch type regulated power supply with small size, simple circuit, adjustable output and over voltage protection function. Tina-TI software was used for simulation analysis, and the main circuit and control circuit were built. The current source of 1.25A and 40kHz output by the secondary side of the toroidal transformer is converted into a stable 10V DC voltage source, which verified the correctness of the design. Tina-TI software can be used to analyze and design power supply with different requirements, improve power efficiency, reduce design complexity, and thus shorten development cycles.

In photovoltaic (PV) grid-connected power generation systems, the needs of low-voltage DC power supply for equipment in PV power plant areas are common. This article provides a design of wide-range high-input voltage flyback power supply. Firstly, the needs of the input voltage range are analysed, and the power supply indexes are defined. Then, the design of the power supply and the transformer circuit are given. The prototype trial results are also given at the last. The results show that the designed power supply meets the requirements of equipment in PV power plant.

The simple pulsewidth modulated (PWM) controller IC has made substantial progress in the last 39 years. Along the way, it has left several milestones. In addition, there is much more to achieve, especially as digital PWM controller chips begin to gain ground in the analog world. From a simple monolithic bipolar chip in 1975, designed by Silicon General‚s cofounder and power designer, Bob Mammano, to control a switched-mode power supply (SMPS), the pulsewidth modulated (PWM) controller architecture and integration has made remarkable progress in the last 39 years. Four decades later, advances in topology, semiconductor processes, and packaging have enabled this simple control circuit with a few functional blocks on a bipolar chip to reach everincreasing levels of integration, resulting in a complete power supply as a single board-mountable component. In addition to stimulating the development of SMPS supplies and creating a gigantic market for switching power supplies, it has also enabled a powermanagement integrated circuits (PMICs) industry that is worth tens of billions of dollars today. By research firm Micro-Tech Consultants' estimate, the switching power supply market comprising ac-dc switchers and dc-dc converters was worth over US$29 billion last year and is expected to increase to over US$29.5 billion this year.

This paper presents and compares two new digitally programmable structures for the control of DC to DC switching power supplies. The first structure is a switched capacitor, proportional plus integral (PI) based pulse width modulated (PWM) controller with automatic circuit offset and mismatch absorption. The second structure uses a proportional plus integral plus derivative (PID) structure as input to a first order delta-sigma (/spl Delta//spl Sigma/) modulator to eliminate circuit and matching requirements found in existing control structures. It makes use of the low-pass filtering effects of the power supply to filter out the high frequency quantization noise associated with the /spl Delta//spl Sigma/ modulator. Simulation and discrete component lab tests indicate 2% to 3% load regulation with up to 100 Watts of output power.

The proposed paper presents active learning methods using a laboratory module "Switching Forward Single-ended DC/DC Converter" during a laboratory exercise in the course "Power supplies" at the University of Ruse "Angel Kanchev". The "Switching Forward Singleended DC/DC Converter" laboratory module enables students to solidify their knowledge, skills and experience in switching power supplies. During the class, students record basic timing diagrams of input and output voltages, input current, oscillator voltage, control pulses for the power switch, pulse width modulation, and the positive impact of protective circuits. From practical experiments, students receive results for load characteristics with and without feedback from the switching forward single-ended DC/DC converter.

A high precision and output stability of the AC sine wave online uninterruptible power supply (UPS), the design is intended to demonstrate the advantages and disadvantages of the circuit design, get relevant data, so the output of 24 V switching power supply instead of the battery. In the selection of power supply circuit, the characteristics of one-way conduction of the transistor are used. When the 36 V power supply is supplied, the standby power side voltage is only 24 V, and the subsequent electricity is supplied by the power side. When the power side is cut off, the 24 V standby power supply (i.e. energy storage device) side becomes the high voltage side, and the transistor turns on to achieve the purpose of instantaneous switching. The inverter circuit based on the EGS002 inverter driver board and the power electronics converter technology, has the functions of stable output, low distortion rate, visual output data, etc., so that the uninterruptible power supply can output the single-phase sinusoidal alternating current with the frequency of 50 ± 0.2 Hz, 30 V ± 0.2 V.KeywordsUPSRectifierInverterEGS002

Switching power supplies are widely used in automotive, aviation, and DC speed control fields. Its biggest requirement is stable output and high efficiency. It is usually realized by resonant converters, but its control circuit is complex and the output ripple is large. In this paper, a new type of flyback switching power supply is designed using a flyback conversion circuit and a single-tube self-excited conversion circuit. Experiments have shown that the designed switching power supply improves the efficiency and reliability of the power supply while obtaining a small ripple, continuously adjustable, and stable DC voltage.

Full-bridge phase-shifting zero voltage switching (ZVS) pulse width modulation (PWM) circuit adopts phase control and by resonance, the circuit can realize zero voltage conduct of switch device, eliminate conduct loss. However, the lagging legs of full-bridge circuit is difficult to realize ZVS in a little current. The main circuit topological structure of full-bridge phase-shifting ZVS high frequency power supply based on adaptive delay control technology is applied in this paper. By adaptive delay control technology, it can detect voltage of power grid and bridge arm midpoint in real time, and expand the ZVS operating range by adjusting the triggered time of switch devices. The main transformer and resonance inductance parameters are designed in this paper. The experimental results proved that adaptive delay control technology can expand the ZVS operating range, and improve the efficiency of the power supply.

In this paper, a HV and HF switch power supply was designed, which was controlled through a single chip microcomputer, also the MOSFET was used as the switch power tube. The PWM (pulse width modulation) technique and half-bridge inverter topology have been used to invert AC into the DC that can be adjust from 0V~25KV and the operating frequency is 35KHz, Through the simulation with the Saber software and practical use, the feasibility of the scheme and the correctness of the design have been verified.

In respect to the difficulties in power supply for online monitoring equipments at high voltage side, a new design of adjustable and rechargeable induction power supply is presented. A microprocessor is used as the central control unit, which can achieve the intelligent management and control of different modules of the proposed device. The experimental results show that reliable and stable power output can be obtained in the situation of large current variation. Introduction The security and stability of the high voltage transmission lines are very important in the development of smart grid. As a result, different kinds of auxiliary devices are installed on high voltage transmission lines to improve the capability of condition monitoring [1]. However, due to the electrical isolation of safety requirements [2], the electronic monitoring equipments installed on the high voltage side can not be directly powered from the low voltage side. Therefore, the power supply has become one of the key technologies which restrict the development of online monitoring systems. The traditional power supplies, for example, solar energy [3], are unable to provide the monitoring equipments an all-weather, continuous and stable power supply. The induction power supply at high voltage side can work in harsh weather and provide stable and continuous output [4], which makes it an ideal choice for online monitoring equipments to solve their energy supply problem. However, since the current of the transmission lines varies in a wide range, it is crucial how to ensure that the induction power supply device has a stable and reliable output with a wide range of current fluctuation. It is necessary to ensure that the power supply can provide sufficient driving power to the online monitoring equipment when the current of the transmission line is small [5]. It is also needed to ensure that when large current flows in the transmission line, a sustainable and stable power supply still can be obtained. Therefore, a new design of adjustable and rechargeable induction power supply at high voltage side is studied. The proposed induction power supply can produce reliable and stable power supply in the condition of large current variation. The Structure of the Proposed Power Supply Fig. 1. The overall framework of the proposed induction power supply The proposed induction power supply consists of the power capture module, the rectifier module, the over-voltage protection module, the voltage regulator module, the backup power management 4th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2016) © 2016. The authors Published by Atlantis Press 1195 module and the microprocessor control unit (MCU), as shown in Fig. 1. With the MCU, the entire device can be intelligently controlled to produce a stable DC voltage output even with a large current variation in the transmission line [6]. The details of each module of the proposed induction power supply are presented as follows. Power Capture Module. The structure of the power capture module is shown in Fig. 2. The actual current in the high-voltage transmission lines keeps changing. In order to adapt to the dynamic current changes, there are multiple taps at the CT coil in the secondary side. Different taps correspond to coils with different numbers of turns. With the sampling resistor in the rectifier module, the MCU can achieve a real-time control on the number of coil turns. When the current in the transmission line is too large, the current at the secondary side also becomes large. The MCU controls the relay 1 and then the coil 1 will be connected to the circuit in order to reduce the current at the secondary side. When the current in the transmission line is in normal variation, the MCU controls the relay 1 and then the coil 2 is connected. Finally, if the current in the transmission line is too small, then the backup battery may be switched on to power the equipment. Such a design makes the proposed device having efficient power capture capability over a wide range of current variations. Fig. 2. The structure of the power capture module Rectifier Module. Rectifier circuit DB107 is used in this design. RC filter and LC filter are connected in parallel. A transient suppression diode TVS, which plays the role of over-current protection, is inserted between the rectifier circuit and the filter. The selected TVS is SMF45A, which has a breakdown voltage of 75 V and a cut-off voltage of 45 V. Fig. 3. The structure of the rectifier module Voltage Regulator Module. The voltage of the DC output of the rectifier module is 7.5 V – 76 V. The role of the DC-DC voltage regulator module is to convert this wide range of input voltage into a stable but adjustable output voltage. In our design, the step-down voltage converter MAX5035BASA is chosen as the core unit of this module. It has high efficiency and wide input voltage range up to 76 V. Its output voltage is fixed to 5 V. Fig. 4 shows the circuit of this module.

TDA 16888 is designed for off-line switched mode power supplies (SMPS) with optional universal input and power factor correction, for example, for PCs, monitors, CTVs and industrial applications. Combi-IC TDA 16888 includes the pulse width modulated (PWM) control for a SMPS and the control for the preconverter to improve the power factor and to reduce the harmonics of the AC input current. Both sections are internally synchronized on the same operating frequency. The preferred topology of the PFC-preconverter is boost, but flyback is also possible. The PWM section can be designed as a forward or as a flyback converter. Maximum duty cycle of the PFC is about 95%, in order to achieve minimal line current gaps. Maximum duty cycle of the PWM is limited to 50% to prevent transformer saturation. In normal operation the PFC section operates with dual loop control. A first control loop controls the shape of the line current by average current control enabling either continuous or discontinuous operation mode. The second loop controls the DC bus voltage. There is a third control loop available that enables the PFC section as an auxiliary power supply even during disabling the PWM section. In this paper the PFC preconverter, PWM converter, PFC and PWM gate drive, and oscillator and synchronisation are described.

The first fully integrated GaN pulse width modulation (PWM) generator for power conversion applications is presented in this paper. The solution is implemented in a 0.5-μm technology, avoiding additional pins and external capacitors for sawtooth signal generation while providing high accuracy. Indeed, the large GaN process spreads are addressed through an innovative dynamic offset compensation approach whose clock signal takes advantage of the PWM signal itself. The proposed PWM generator adopts a 6-V power supply and includes a 25 digital divider to set the PWM frequency at 500 kHz and the minimum and maximum duty cycles at 6% and 94%, respectively. Experimental results on integrated prototypes validated the correct circuit functionality over the temperature range from -40°C to 120°C. As a main achievement, this work demonstrates effective all-GaN integration of complex mixed analog and digital circuits, thus representing a significant advancement in the approaches to overcome the main limitations of GaN devices and enable fully integrated signal processing implementation.

The authors describe a method for selecting pulse width modulation (PWM) patterns and a method for designing low-pass filters in large-capacity current source PWM power converters, to suppress higher harmonics flowing into the power supply. A test carried out on a 500 kVA PWM converter, employing the proposed methods, verified that they substantially decrease higher harmonics flowing into the power supply. The test also showed highly efficient converter characteristics with a supply power factor equaling almost 1.0.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The rapid developments of computer industry and semiconductor processes lead to high component density, high-energy dissipation, and compact volume of the electronic components in systems. Those are especially true for the high-energy density of the CPUs, resulting in high temperature rise for the electronic chips. To preserve the life span of the integrated circuits and to ensure their proper functions, it is necessary to develop proper means for evaluating the related thermal management in order to effectively dissipate the energy released from these electronic parts and systems. This project used Icepak 4.0, developed by Fluent, to determine thermal-fluidic behaviors of the notebook computer, desktop computer, and switch power supply, under an environmental temperature of 35°C. In addition, parametric studies were carried out to evaluate the distribution of temperature inside the systems under investigation and the effectiveness of overall thermal management for the systems. Icepak uses the unstructured grid generation technique for the three-dimensional modeling of the electronic components and systems. With the computational fluid dynamics (CFD) solver employed by Fluent and using the finite volume method, Icepak simulates the flow and temperature fields inside the system or component of concern. Parametric studies — including the positions for venting, the locations for the cooling fans, the directions of flow for the fans (either by blowing or suction), and the number of fins used for heat dissipation — were carried out to determine the effectiveness of the thermal management designs of the desktop computer, notebook computer, and switch power supply under an environment temperature of 35 °C. Results of this study indicated that the peak component temperatures for the three systems under study are 84 °C, 80 °C, and 81 °C, respectively, while the maximum allowable temperatures suggested by the manufacturers of these three items are 85 °C, 90 °C, and 85 °C, respectively.

In the aerospace industry, interest has been growing in monitoring the ongoing health of electronic products and systems to predict failures and provide early warnings for any catastrophic failures. Switch-mode power supplies form an integral part of the avionic line replaceable unit (LRU). Any failure in its operation will cause malfunctioning of the complete electronics and the system thereafter. Point-of-load (POL) converters in particular are non-isolated buck converters that provide low output voltage DC power close to the loads. In the last decade, the average LRU supplies evolved from a basic four output voltages to more than twenty output voltages, due to the increased number of low-voltage supply pins on Very Large Scale Integrated (VLSI) circuits. This increased number of POL converters mathematically increases power supply failure rates, hence the importance of being able to predict them. This paper presents a brief review of failures/degradation experienced by POL converters in avionic systems. Capabilities of currently used analog Pulse-Width Modulator (PWM) controllers and the digitally-controlled PWMs for health monitoring of electronic systems are addressed. Lastly, the technique of system identification for health monitoring of POL converter using Digital Pulse-Width Modulator (DPWM) circuits is proposed.