Optimized design of high power density EMI filters for power electronic converters

Nowadays, power density of power converters and related EMI filters is gaining more and more attention. This severely impacts on the design constraints in several application domains. A conventional design of the EMI filter does not guarantee the selection of components/configuration leading to the best power density. For this reason, an optimized design procedure of discrete EMI filters in terms of power density is proposed in this paper. It is based on a previously developed rule-based design procedure, introducing here additional features to obtain a more effective optimization of EMI filter's power density. The proposed approach has been validated in terms of EMI filter's performance and size reduction, by a comparison between an EMI filter designed using the optimized procedure and a conventionally designed one, for two different case studies

High Switching Frequency SEPIC Regulator With FPGA Controller

The increasing need for smaller and more efficient DC to DC regulators has motivated researches to look for alternate methods for designs. As electronic designs become smaller on size, the challenge of reducing design’s size increases. DC to DC regulators occupy a large space of any electronic due to necessary components to obtain the expected functionality and efficiency. In addition, the voltage ripple on the output voltage is a very important factor as devices required a more precise input voltage to define different threshold voltages. Signal interference with noise-sensitive frequency bands such as AM radio is another important factor designer must observe when designing DC to DC regulators. In addition, with newer technologies such as USB Type-C which allows for up to 100W using USB PD specification requires that DC to DC regulators have a higher efficiency due to the heat that must be dissipated. Transient responses during switching process is another important factor for DC to DC regulators (Benefits). This research will target the main design considerations when implementing DC to DC regulators. Another important factor not mentioned yet is the BOM (bill of materials) cost, which will be reduced by the end product of the research

Evaluation and implementation of a 5-level hybrid DC-DC converter

In this work, a hybrid voltage regulator topology is analyzed, implemented, and evaluated. The common topologies of DC-DC converters have proven to be lacking in some aspects, such as integrability for buck converters, or maximum efficiency for switched-capacitor regulators. The hybrid topology tackles these shortcomings by combining the advantages of switched-capacitor and inductor-based voltage regulators. A 5-level buck converter is evaluated, implemented, and compared to other converter implementations using the same components. The 5-Level Buck converter can achieve 5 different levels, allowing it to cover 4 operation regions, each between 2 levels. Accordingly, it covers a wide range of output voltages. By reducing the voltage difference at the inductor input, the 5-level buck converter can use smaller inductor compared to both 3-level and conventional buck converters which makes it cheaper, smaller in size, and much more efficient. Simulations show proper functionality of the 5-Level topology, while putting restrictions on the inductor size, efficiency, and component footprint (or total converter area). A test PCB is implemented for verification of the functionality and experimental measurements show that for the same switching frequency and inductor size, the 5-level buck converter achieves up to 15% efficiency improvement over a conventional buck converter and a 3-level buck converter at certain output voltage ranges. Peak efficiency of 94% has been achieved by the 5-Level hybrid converter, which includes all external switching and conduction losses. The proposed hybrid topology proved to yield high conversion efficiency even in the face of component size limitations, which indicates potential benefit in using multilevel converters for several off-chip as well as on-chip applications

Design and Analysis of Electrical Power and Communication Systems for 3U SeaLion CubeSat Mission

Old Dominion University (ODU) Space Systems students in conjunction with the United States Coast Guard Academy (USCGA) are designing and developing a 3U Very Low Earth Orbit (VLEO) CubeSat mission aptly named SeaLion. This work specifically details the design of the Electrical Power System (EPS) and Communication System of the satellite. Electrical power in orbit is a precious commodity and must be carefully regulated and distributed to ensure the satellite’s operational health. Commonly, CubeSat electrical power is retained in orbit via outward facing solar cells and stored in onboard rechargeable batteries. This thesis proposes using non-rechargeable primary battery cells and custom hardware to maximize operational time with strict Very Low orbital lifetime constraints. Primary battery cell choice and the encompassing battery power supply design with reliability features are provided. Major functions of the EPS including voltage and current regulation and circuit protection and monitoring are also designed and analyzed for performance and reliability. The communication system consists of two half-duplex radios centered in the UHF and S-Band frequency bands to communicate with the Virginia CubeSat Constellation (VCC) and Mobile CubeSat Command and Communications (MC3) ground station networks, respectively. The design and analysis provided show the viability and cost efficiency of using primary cells and custom and readily available hardware for Very Low Earth Orbit CubeSat missions

Efficiency Improvement of LDO Output Based Linear Regulator With Supercapacitor Energy Recovery – A versatile new technique with an example of a 5V to 1.5V version

Supercapacitors are used in various industrial applications and the supercapacitors technology is gradually progressing into a mature state. Common applications of supercapacitors are in electric vehicles, hybrid electric vehicles, uninterruptible power supply (UPS) and in portable devices such as cellular phones and laptops. The capacitance values range from fractional Farads to few thousand Farads and their continuos DC voltage ratings are from 2V to 6V. At University of Waikato, a team works on using supercapacitors for improving the efficiency of linear voltage regulators. In particular, this patented technique aims at combining off the shelfs LDO ICs and a supercapacitor array for improving end to end efficiency of linear regulator. My work is aimed at developing the theoretical background and designing prototype circuitry for a voltage regulator for the case of unregulated input supply is more than 3 times of the minimum input voltage requirement of the LDO which is applicable for a 5V to 1.5V regulator. Experimental results are indicated with future suggestions for improvement

Design Techniques of Highly Integrated Hybrid-Switched-Capacitor-Resonant Power Converters for LED Lighting Applications

The Light-emitting diodes (LEDs) are rapidly emerging as the dominant light source given their high luminous efficacy, long lift span, and thanks to the newly enacted efficiency standards in favor of the more environmentally-friendly LED technology. The LED lighting market is expected to reach USD 105.66 billion by 2025. As such, the lighting industry requires LED drivers, which essentially are power converters, with high efficiency, wide input/output range, low cost, small form factor, and great performance in power factor, and luminance flicker. These requirements raise new challenges beyond the traditional power converter topologies. On the other hand, the development and improvement of new device technologies such as printed thin-film capacitors and integrated high voltage/power devices opens up many new opportunities for mitigating such challenges using innovative circuit design techniques and solutions. Almost all electric products needs certain power delivery, regulation or conversion circuits to meet the optimized operation conditions. Designing a high performance power converter is a real challenge given the market’s increasing requirements on energy efficiency, size, cost, form factor, EMI performance, human health impact, and so on. The design of a LED driver system covers from high voltage AC/DC and DC/DC power converters, to high frequency low voltage digital controllers, to power factor correction (PFC) and EMI filtering techniques, and to safety solutions such as galvanic isolation. In this thesis, we study design challenges and present corresponding solutions to realize highly integrated and high performance LED drivers combining switched-capacitor and resonant converters, applying re-configurable multi-level circuit topology, utilizing sigma delta modulation, and exploring capacitive galvanic isolation. A hybrid switched-capacitor-resonant (HSCR) LED driver based on a stackable switched-capacitor (SC) converter IC rated for 15 to 20 W applications. Bulky transformers have been replaced with a SC ladder to perform high-efficiency voltage step-down conversion; an L-C resonant output network provides almost lossless current regulation and demonstrates the potential of capacitive galvanic isolation. The integrated SC modules can be stacked in the voltage domain to handle a large range of input voltage ranges that largely exceed the voltage limitation of the medium-voltage-rated 120 V silicon technology. The LED driver demonstrates > 91% efficiency over a rectified input DC voltage range from 160 VDC to 180 VDC with two stacked ICs; using a stack of four ICs > 89.6% efficiency is demonstrated over an input range from 320 VDC to 360 VDC . The LED driver can dim its output power to around 10% of the rated power while maintaining >70% efficiency with a PWM controlled clock gating circuit. Next, the design of AC main rectifier and inverter front end with sigma delta modulation is described. The proposed circuits features a pair of sigma delta controlled multilevel converters. The first is a multilevel rectifier responsible for PFC and dimming. The second is a bidirectional multilevel inverter used to cancel AC power ripple from the DC bus. The system also contains an output stage that powers the LEDs with DC and provides for galvanic isolation. Its functional performance indicates that integrated multilevel converters are a viable topology for lighting and other similar applications

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

Analysis on Supercapacitor Assisted Low Dropout (SCALDO) Regulators

State-of-the-art electronic systems employ three fundamental techniques for DC-DC converters: (a) switch-mode power supplies (SMPS); (b) linear power supplies; (c) switched capacitor (charge pump) converters. In practical systems, these three techniques are mixed to provide a complex, but elegant, overall solution, with energy efficiency, effective PCB footprint, noise and transient performance to suit different electronic circuit blocks. Switching regulators have relatively high end-to-end efficiency, in the range of 70 to 93%, but can have issues with output noise and EMI/RFI emissions. Switched capacitor converters use a set of capacitors for energy storage and conversion. In general, linear regulators have low efficiencies in the range 30 to 60%. However, they have outstanding output characteristics such as low noise, excellent transient response to load current fluctuations, design simplicity and low cost design which are far superior to SMPS. Given the complex situation in switch-mode converters, low dropout (LDO) regulators were introduced to address the equirements of noise-sensitive and fast transient loads in portable devices. A typical commercial off-the-shelf LDO has its input voltage slightly higher than the desired regulated output for optimal efficiency. The approximate efficiency of a linear regulator, if the power consumed by the control circuits is negligible, can be expressed by the ratio of Vo/Vin. A very low frequency supercapacitor circulation technique can be combined with commercial low dropout regulator ICs to significantly increase the end-to-end efficiency by a multiplication factor in the range of 1.33 to 3, compared to the efficiency of a linear regulator circuit with the same input-output voltages. In this patented supercapacitor-assisted low dropout (SCALDO) regulator technique developed by a research team at the University of Waikato, supercapacitors are used as lossless voltage droppers, and the energy reuse occurs at very low frequencies in the range of less than ten hertz, eliminating RFI/EMI concerns. This SCALDO technique opens up a new approach to design step-down, DC-DC converters suitable for processor power supplies with very high end-to-end efficiency which is closer to the efficiencies of practical switching regulators, while maintaining the superior output specifications of a linear design. Furthermore, it is important to emphasize that the SCALDO technique is not a variation of well-known switched capacitor DC-DC converters. In this thesis, the basic SCALDO concept is further developed to achieve generalised topologies, with the relevant theory that can be applied to a converter with any input-output step-down voltage combination. For these generalised topologies, some important design parameters, such as the number of supercapacitors, switching matrix details and efficiency improvement factors, are derived to form the basis of designing SCALDO regulators. With the availability of commercial LDO ICs with output current ratings up to 10 A, and thin-prole supercapacitors with DC voltage ratings from 2.3 to 5.5 V, several practically useful, medium-current SCALDO prototypes: 12V-to-5V, 5V-to-2V, 5.5V-to-3.3V have been developed. Experimental studies were carried out on these SCALDO prototypes to quantify performance in terms of line regulation, load regulation, efficiency and transient response. In order to accurately predict the performance and associated waveforms of the individual phases (charge, discharge and transition) of the SCALDO regulator, Laplace transform-based theory for supercapacitor circulation is developed, and analytical predictions are compared with experimental measurements for a 12V-to-5V prototype. The analytical results tallied well with the practical waveforms observed in a 12V-to-5V converter, indicating that the SCALDO technique can be generalized to other versatile configurations, and confirming that the simplified assumptions used to describe the circuit elements are reasonable and justifiable. After analysing the performance of several SCALDO prototypes, some practical issues in designing SCALDO regulators have been identified. These relate to power losses and implications for future development of the SCALDO design

Efficiency improvement of LDO ouput based linear regulator with supercapacitor energy recovery - a versatile new technique with an example of a 5v to 1.5 v version

Supercapacitors are used in various industrial applications and the supercapacitors technology is gradually progressing into a mature state. Common applications of supercapacitors are in electric vehicles, hybrid electric vehicles, uninterruptible power supply (UPS) and in portable devices such as cellular phones and laptops. The capacitance values range from fractional Farads to few thousand Farads and their continuos DC voltage ratings are from 2V to 6V. At University of Waikato, a team works on using supercapacitors for improving the efficiency of linear voltage regulators. In particular, this patented technique aims at combining off the shelfs LDO ICs and a supercapacitor array for improving end to end efficiency of linear regulator. My work is aimed at developing the theoretical background and designing prototype circuitry for a voltage regulator for the case of unregulated input supply is more than 3 times of the minimum input voltage requirement of the LDO which is applicable for a 5V to 1.5V regulator. Experimental results are indicated with future suggestions for improvement