DC-DC Energy Conversion with Novel loaded Resonant Converter

This paper presents the direct current (dc)-to-dc energy conversion with novel loaded-resonant converter. Energy shortages and increasing oil prices have created the demand for a high energy conversion efficiency and performance. The growing electronic product market has increased the demand for high energy conversion efficiency and high power density of dc-to-dc energy power converters. The soft switching scheme is the most attractive dc-to-dc energy conversion topology in recent years. The soft-switching method can reduce switching losses and EMI of the switch-mode converter. Among the many advantages that resonant power conversion has over conventionally adopted pulse-width modulation include a low electromagnetic interference, low switching losses, small volume, and light weight of components due to a high switching frequency, high efficiency, and low reverse recovery losses in diodes owing to a low di/dt at switching instant. The proposed topology comprises a half-bridge inductor-capacitor inductor (L-C-L) resonant inverter and a bridge rectifier. Output stage of the proposed loaded-resonant converter is filtered by a low-pass filter. A prototype dc-to-dc energy converter circuit with the novel loaded-resonant converter designed for a load is developed and tested to verify its analytical predictions. The measured energy conversion efficiency of the proposed novel loaded-resonant topology reaches up to 88.3%. Moreover, test results demonstrate a satisfactory performance of the proposed topology. Furthermore, the proposed topology is highly promising for applications of switching power supplies, battery chargers, uninterruptible power systems, renewable energy generation systems, and telecom power supplies. The experimental results are clearly verified by simulation results

Cascaded Voltage Clamping and LDO Offline Power Supply

Offline power supplies are necessary for any sort of electronic device that utilizes wall power. For offline power supplies, it is a common practice to use the switching mode method where the high voltage AC input is first rectified and then switched at high frequency to a much lower voltage. This method has been known to be very efficient. Also, it’s more efficient than a linear supply method where the AC input is stepped down and then linearly regulated down to a low voltage. Despite the efficiency benefit, the switching method employs a high frequency transformer and inductor. This will make the design relatively costly and bulky (especially at a very low output power). This project will look into a new method of producing a low DC voltage from a high AC input voltage. The method utilizes a switch that prevents the power supply to charge a rectifier capacitor filter all the way up to the peak of the AC input voltage. Rather, the input is clamped at a much lower voltage that is closer to the output voltage such that a low dropout (LDO) regulator could be used; thus, avoiding the use of an inductor while maintaining the high efficiency. The proposed design was tested through LTSpice simulation and results demonstrated the functionality of the design in achieving the desired output voltage. The efficiency of the power supply with the proposed input clamping and LDO method was measured to be above 70% at full load. Construction of a prototype for the proposed design was planned but was not carried out due to the COVID-19 pandemic

Design and Analysis of Multilevel Inverter with Reduced Number of Switches using Multicarrier SPWM Techniques

Multi-level inverter has been widely accepted for high voltage applications. Their performance is highly superior to that of conventional two level inverter due to reduced harmonic distortion, lower electromagnetic interference and higher dc link voltages. Multi-level inverter (MLI) has some disadvantages such as increased number of components, complex pulse width modulation control method, and voltage-balancing problem. In order to increase the level of the output, the numbers of switches are increased and losses and complexity also increased. Hence to reduce these losses and complexity, a new topology is designed in this project i.e. Multi-level inverter (MLI) with reduced number of switches. A new inverter topology has been proposed which has superior features over conventional topologies in terms of the required power switches and isolated dc supplies, control requirements and reliability. In the mentioned topology, the switching operation is separated into high- and low-frequency parts. Design and simulation analysis of new 7 level inverter topology with multicarrier spwm techniques is presented in this project thesis using MATLAB/SIMULIN

Evaluation and mitigation of the undesired effect of DC bias on inverter power transformer

Inverters have traditionally been used mostly in standalone systems (non-grid connected), Uninterruptible Power Supplies (UPS) and, more recently, in distributed generated systems (DGs). DG systems are based on grid connected inverters and are increasingly being connected to utility grids to convert renewable energy sources to the utility grids. Such sources are likely to have a significant impact in the future in meeting the electricity demands of industry and domestic consumption. Common DGs utilize DC power sources such as fuel cells, batteries, photovoltaic (solar) power, and wind power. Most of power supplies in domestic and industries are AC power consumers and, for this reason, the DC power has to be converted to meet the requirement. Two main causes of DC current in inverter power transformer are: 1) Non-linearity and asymmetry in its switching mechanism which may result in undesired DC current at its input. This DC current introduced into an inverter transformer results in the transformer's magnetic flux distortion and in some cases magnetic saturation. This, in turn, results in asymmetrical primary currents in the transformer (inverter side). This is due to the non linear characteristics of the transformer magnetic flux. 2) The same effects can be produced by the connection of asymmetrical loads (e.g. asymmetrical rectifier) to the inverter output. The result in both cases is an asymmetrical magnetic flux in the transformer. This is manifested as even and odd current harmonics as well as an increase in the reactive power requirement from the inverter. vi To remedy this situation, it is, therefore, necessary to incorporate into the inverter's control system a mechanism of cancelling the DC magnetic motive force (mmf) that causes the magnetic flux distortion. This Thesis presents a method of introducing a DC voltage component in the inverter's voltage output so as to inject the necessary DC current into the primary side of the inverter's transformer so as to cancel the total DC mmf that the transformer is subjected to ( supply and load side). This project consists of three main parts namely: Modeling, Simulation and Laboratory Experiment. Activities undertaken under Modeling and Simulation were as follows: Determining the effects of DC current on a power transformer. Investigating the likely occurrence of saturation of the power transformer incorporated in inverter systems. Mitigating the effects that can be caused by the presence of a DC component in the windings of a power transformer. After understanding the literature on the subject of interest, MATLAB SIMULINK and MATLAB m-files were used to simulate the behavior of the power transformer under three situations : The transformer under linear load. The transformer subjected to asymmetrical loading. The inverter system that has a power transformer on its output were designed in MATLAB and used to simulate the situation for each case. To validate the theory and simulation results, experimental work was carried out as follows: vii Investigation of the effects that DC (current) injection can have on a 6 kVA power transformer. Investigation of the performance of a 6 kVA power transformer under linear loading. Investigation of the performance of a 6 kVA power transformer under non-linear loads. Investigation of the likely occurrence of DC offset in inverter system. Mitigation of the effect of DC bias on power transformer using extra windings. Mitigation of the effects of DC offset in power inverter transformer by using the second harmonic content of the primary current as a feedback signal. Results obtained showed a successful implementation of the proposed method. However limitations of the controller performances were experienced and will require future work. It was concluded that a total removal of the undesired effects of DC bias is achievable and that total removal of DC offset in power inverter transformer is possible if the limitations of the controller are overcome

Stray inductance effects and protection in GTO thyristor circuits

The recently developed gate turn-off thyristor is now becoming well established as the first choice switching device in high power converters for applications such as uninterruptible power supplies, frequency changers, and AC and some DC variable speed motor drives. The special operating features of these devices in conventional circuit configurations are investigated. The GTO thyristor physical behaviour and operating characteristics are first described and supported by measurements made at turn-off currents of up to 600A on a specially constructed test circuit. From this, it is shown that, owing to the extremely fast rates of fall of anode current at turn-off, voltage overshoot effects caused by the stray circuit inductances are highly dangerous to the device, and effective snubbing is essential. A detailed study of these stray inductance effects in constructed DC chopper and H-bridge inverter circuits follows. The circuits are modelled to include these strays, with appropriate mathematical analysis and computer simulation, to determine which stray inductances are the most influential in causing GTO thyristor voltage stress. The different switching patterns are considered for the H-bridge to provide quasi-square and various pulse width modulated (PWM) output voltage waveforms, and the detailed current transfer paths in the various circuit devices and snubber components defined and mathematically analysed in each case. Practical switching effects of diode reverse recovery and GTO mismatched switching times are demonstrated and possible damaging conditions revealed. All analytical and computed results are supported by experimental measurements. A GTO thyristor will be damaged by attempting to turn-off an over-current, and satisfactory protection against this is essential. Conventional fusing is usually inadequate, and a better method is to use a fast active system utilising either a crowbar and fuse, or rapid direct gate turn-off. Both methods are investigated and experimental results provided. It is concluded that, with appropriate circuit layout and component choice, the unavoidable stray inductance effects can be limited to manageable levels. The most severe effects are caused by the DC source inductance which is the most difficult to minimise. Others within the power circuit, if kept small, will have a marginal effect. Fast over-current protection is achievabl

On-Chip Power Management System Based CMOS Reconfigurable Switched Capacitor DC-DC Converter For Battery-Less Iot Soc

In recent studies, Radio Frequency (RF) energy harvesting method showed a great potential for indefinite battery lifetime for Internet of Things (IoT) System on Chip (SoC) application which is a system with functional blocks that includes sensors, memory, processing, and data transmission unit. However, the harvested energy is not stable and could not supply enough energy as required by each functional block of IoT SoC. Thus, it needs to be regulated and reconfigured to different levels of Direct Current (DC) supplies. Switched Capacitor (SC) DC-DC converter can be used for this purpose since it can regulate the energy to a stable level by stepping it up or down. But this conventional design has a drawback in fix conversion ratio, thus limited only to either step-up or step-down mode at one time and not simultaneously. Another drawback is SC DC-DC converter is only suitable for low load current application which is only in µA range, thus it requires a Low Dropout (LDO) voltage regulator added as an additional block to fulfil the requirement for high load current in microampere (mA) range. Hence, this work presents the design of a reconfigurable on-chip power management system based on CMOS SC DC-DC converter that can operate in both step-up and step-down simultaneously for battery-less IoT SoC. A method to achieve reconfigurability is proposed based on switching frequency parameter that is generated by Current-Starved Voltage-Controlled Oscillator (CSVCRO). Based on the simulation result, the CSVCRO enables the SC DC-DC converter to operate in both step-up and step-down modes for an input voltage range of 0.9V to 1.5V. The LDO design consists of error amplifier, bandgap voltage reference, feedback network resistor and series-pass transistor. NMOS transistor has been proposed to replace conventional Bipolar Junction Transistor (BJT) in bandgap voltage circuit to overcome the error amplifier input transistor driving voltage problem. In the simulation, the LDO performance has achieved 90.85dB of open-loop gain, 76.39º of phase margin and 63.46dB of Power Supply Ripple Rejection (PSRR) respectively. The simulations had also been validated through fabrication, measurement analysis, and benchmarking with existing works. Furthermore, it can be seen that the stability of the proposed design is higher compared to the previous research work which is at 75º. It is hopeful that the contribution from this work can be used to achieve more advancement in power management unit development based on CMOS technology and be the future of the microelectronic field

Resonant power converter control for industrial magnetron

High voltage DC power supplies have been used in a wide range of applications such as Radio Frequency (RF) tube drives, industrial, military, aerospace, medical, and domestic applications. Recently as a result of advances in power electronics and magnetic materials, development of compact high voltage DC power supplies has become an active area of research, and resonant power converters have been introduced as a promising solution, owing to their potential for high efficiency and high power density. Several resonant converter topologies have been investigated to be used as modulators for supplying RF tubes (i.e. Magnetrons, Klystrons, and Traveling Wave Tubes) for various applications. The main aim of this study is to develop a control methodology for maintaining soft switching of a series resonant series loaded (SRSL) power converter based modulator for driving an industrial magnetron with variable load conditions. This thesis considers the design of a high voltage, high frequency, compact power supply for applications where the load is variable and/or nonlinear. One particular application where this is the case is when driving an industrial magnetron with a variable output RF energy requirement. The magnetron appears to the resonant converter as a variable load which can negatively affect the efficiency of the power conversion unless control of the converter is carefully considered. A compact power supply based on the SRSL resonant converter with an extended combined phase and frequency control is proposed. A novel control method based on three dimensional (3D) lookup tables has been developed, in order to control the load resonant converter whilst maintaining soft switching under variable load conditions. A direct quadrature (DQ) based modelling approach is used to develop a suitable model of the converter for control design. Based on the characteristics of the magnetron, an emulator prototype is also proposed to represent the magnetron load behavior in a low voltage laboratory environment. A detailed design and implementation procedure is presented, including the hardware design and control of the resonant power converter and the magnetron emulator. Simulation and experimental results are provided to validate the approach and in order to demonstrate the feasibility of the proposed converter modelling approach and control strategy. A good correlation between simulation and experimental results is obtained

Resonant power converter control for industrial magnetron

High voltage DC power supplies have been used in a wide range of applications such as Radio Frequency (RF) tube drives, industrial, military, aerospace, medical, and domestic applications. Recently as a result of advances in power electronics and magnetic materials, development of compact high voltage DC power supplies has become an active area of research, and resonant power converters have been introduced as a promising solution, owing to their potential for high efficiency and high power density. Several resonant converter topologies have been investigated to be used as modulators for supplying RF tubes (i.e. Magnetrons, Klystrons, and Traveling Wave Tubes) for various applications. The main aim of this study is to develop a control methodology for maintaining soft switching of a series resonant series loaded (SRSL) power converter based modulator for driving an industrial magnetron with variable load conditions. This thesis considers the design of a high voltage, high frequency, compact power supply for applications where the load is variable and/or nonlinear. One particular application where this is the case is when driving an industrial magnetron with a variable output RF energy requirement. The magnetron appears to the resonant converter as a variable load which can negatively affect the efficiency of the power conversion unless control of the converter is carefully considered. A compact power supply based on the SRSL resonant converter with an extended combined phase and frequency control is proposed. A novel control method based on three dimensional (3D) lookup tables has been developed, in order to control the load resonant converter whilst maintaining soft switching under variable load conditions. A direct quadrature (DQ) based modelling approach is used to develop a suitable model of the converter for control design. Based on the characteristics of the magnetron, an emulator prototype is also proposed to represent the magnetron load behavior in a low voltage laboratory environment. A detailed design and implementation procedure is presented, including the hardware design and control of the resonant power converter and the magnetron emulator. Simulation and experimental results are provided to validate the approach and in order to demonstrate the feasibility of the proposed converter modelling approach and control strategy. A good correlation between simulation and experimental results is obtained

Discussion of the technology and research in fuel injectors common rail system

Common rail is one of the most important components in a diesel and gasoline direct injection system. It features a high-pressure (100 bar) fuel rail feeding solenoid valves, as opposed to a low-pressure fuel pump feeding unit injectors. Third-generation common rail diesels now feature piezoelectric injectors for increased precision, with fuel pressures up to 2,500 bar. The purpose of this review paper is to investigate the technology and research in fuel injectors common rail system. This review paper focuses on component of common rail injection system, pioneer of common rail injection, characteristics of common rail injection system, method to reduce smoke and NOx emission simultaneously and impact of common rail injection system. Based on our research, it can be concluded that common rail injection gives many benefit such as good for the engine performance, safe to use, and for to reduce the emission of the vehicle. Fuel injection common rail system is the modern technology that must be developed. Nowadays, our earth is polluting by vehicle output such as smoke. If the common rail system is developed, it can reduce the pollution and keep our atmosphere clean and safe

Harmonic correction in power supplies feeding non-linear loads

This paper focuses on the design of an electronic circuit which can be used in conjunction with the power supplies used at the input of non-linear loads (computers, TV sets, etc.) in order to filter out the input current harmonics in such loads. The electronic circuit will fill the gaps of the distorted current waveform so that it becomes sinusoidal and also in phase with the mains supply. In this paper different configurations of the proposed electronic circuit are covered (depending on the location with respect to the non-linear load). An optimization algorithm is carried out in order to find the best location, minimum device rating for different type of loads. The proposed circuit monitors the input current, output voltage and power rating of the power supply. The circuit will then decide whether to filter the input current harmonics or the output voltage harmonics. The circuit will also optimize the best switching frequency for the required load so that the power supply operates at the maximum possible efficiency