Modern switch-mode power supplies (SMPS) used for point-of-load (PoL) applications need to meet increasingly stringent requirements on voltage regulation, while minimizing physical volume and optimizing conversion efficiency. The focus of this thesis is the voltage regulation capability of low-power PoL converters during load transients. The main objective is to investigate converter topologies and control techniques that can achieve fast and smooth transient performance without significant penalty in volume and efficiency. The digital control method is used due to its ability to implement sophisticated control algorithms. The first part of this thesis investigates a dual output stages converter, with a small auxiliary output stage connected in parallel with the main output stage. While the main output stage is responsible for steady-state operation and designed to achieve optimum efficiency, the auxiliary stage is activated when a load transient occurs, to help suppress voltage deviation. Experimental results on a 6 V-to-1 V, 3W buck converter shows 35% improvement in peak transient voltage deviation while maintaining the same efficiency profile, compared to an equivalent buck converter. The second part of this thesis introduces a flyback-transformer based buck (FTBB) converter. In this topology, the conventional buck inductor is replaced with the primary winding of the flyback transformer, an extra switch, and a set of small auxiliary switches on the secondary side. During heavy-to-light load transients the inductor current is steered away from the output capacitor to the input port, achieving both energy recycling and savings due to reduced voltage overshoots. The light-to-heavy transient response is improved by reducing the equivalent inductance of the primary transformer winding to its leakage value. Compared to an equivalent buck converter, experiment results on a 6 V-to-1 V, 3 W prototype show three times smaller maximum output voltage deviation during load transients and, for frequently changing loads, about 7% decrease in power losses.

The purpose of this thesis is to introduce a family of interactive Switch Mode Power Supplies (SMPS) for reducing the overall volume of the conventional converter topologies in low-to-medium power (up to 60W) applications. As shown in this thesis, the interaction between power supplies and electronic devices can be incorporated with emerging digital controllers for SMPS, to implement flexible converter topologies. These flexible topologies dynamically change the converter configuration, based on the load requirement, to provide near ideal transient response and/or improved efficiency over a wide range of operating conditions. This interaction relaxes the energy storage requirement for the converter reactive components and results in a low volume implementation. The interaction with the SMPS can be between the electronic load and the power supply or different conversion stages of a multi-stage converter. The effectiveness of the introduced family of SMPS is verified on digitally controlled dc-dc and ac-dc converter topologies.

Modern switch-mode power supplies (SMPS) used for point-of-load (PoL) applications need to meet increasingly stringent requirements on voltage regulation, while minimizing physical volume and optimizing conversion efficiency. The focus of this thesis is the voltage regulation capability of low-power PoL converters during load transients. The main objective is to investigate converter topologies and control techniques that can achieve fast and smooth transient performance without significant penalty in volume and efficiency. The digital control method is used due to its ability to implement sophisticated control algorithms. The first part of this thesis investigates a dual output stages converter, with a small auxiliary output stage connected in parallel with the main output stage. While the main output stage is responsible for steady-state operation and designed to achieve optimum efficiency, the auxiliary stage is activated when a load transient occurs, to help suppress voltage deviation. Experimental results on a 6 V-to-1 V, 3W buck converter shows 35% improvement in peak transient voltage deviation while maintaining the same efficiency profile, compared to an equivalent buck converter. The second part of this thesis introduces a flyback-transformer based buck (FTBB) converter. In this topology, the conventional buck inductor is replaced with the primary winding of the flyback transformer, an extra switch, and a set of small auxiliary switches on the secondary side. During heavy-to-light load transients the inductor current is steered away from the output capacitor to the input port, achieving both energy recycling and savings due to reduced voltage overshoots. The light-to-heavy transient response is improved by reducing the equivalent inductance of the primary transformer winding to its leakage value. Compared to an equivalent buck converter, experiment results on a 6 V-to-1 V, 3 W prototype show three times smaller maximum output voltage deviation during load transients and, for frequently changing loads, about 7% decrease in power losses.

The purpose of this thesis is to introduce a family of interactive Switch Mode Power Supplies (SMPS) for reducing the overall volume of the conventional converter topologies in low-to-medium power (up to 60W) applications. As shown in this thesis, the interaction between power supplies and electronic devices can be incorporated with emerging digital controllers for SMPS, to implement flexible converter topologies. These flexible topologies dynamically change the converter configuration, based on the load requirement, to provide near ideal transient response and/or improved efficiency over a wide range of operating conditions. This interaction relaxes the energy storage requirement for the converter reactive components and results in a low volume implementation. The interaction with the SMPS can be between the electronic load and the power supply or different conversion stages of a multi-stage converter. The effectiveness of the introduced family of SMPS is verified on digitally controlled dc-dc and ac-dc converter topologies.

Práce se zabývá popisem jednotlivých typů zdrojů s důrazem na izolované topologie. Poté je rozebírána nejvhodnější volba pro zdroj na anodické bondování, kde jsou kladeny požadavky na vysoké výstupní napětí s malým proudem. Další část rozebírá problematická místa návrhu a na co je třeba dávat pozor. Poté je proveden vlastní návrh zdroje s popisem optimalizačních kroků. Tento zdroj je odsimulován. Dva rozdílné přístupy k realizaci takového zdroje jsou poté porovnány a nejlepší je vybrán. Je ukázána možnost, jak realizovat bipolární výstup. V poslední části je tento zroj sestaven a proměřeny jeho parametry.

This thesis focuses on the study, implementation and improvement of a digital controller for a power factor correction (PFC) converter. The development of the telecommunications industry and the Internet demands reliable, cost-effective and intelligent power. Nowadays, the telecommunication power systems have output current of up to several kilo amperes, consisting of tens of modules. The high-end server system, which holds over 100 CPUs, consumes tens of kilowatts of power. For mission-critical applications, communication between modules and system controllers is critical for reliability. Information about temperature, current, and the total harmonic distortion (THD) of each module will enable the availability of functions such as dynamic temperature control, fault diagnosis and removal, and adaptive control, and will enhance functions such as current sharing and fault protection. The dominance of analog control at the modular level limits system-module communications. Digital control is well recognized for its communication ability. Digital control will provide the solution to system-module communication for the DC power supply. The PFC converter is an important stage for the distributed power system (DPS). Its controller is among the most complex with its three-loop structure and multiplier/divider. This thesis studies the design method, implementation and cost effectiveness of digital control for both a PFC converter and for an advanced PFC converter. Also discussed is the influence of digital delay on PFC performance. A cost-effective solution that achieves good performance is provided. The effectiveness of the solution is verified by simulation. The three level PFC with range switch is well recognized for its high efficiency. The range switch changes the circuit topology according to the input voltage level. Research literature has discussed the optimal control for both range-switch-off and range-switch-on topologies. Realizing optimal analog control requires a complex structure. Until now optimal control for the three-level PFC with analog control has not been achieved. Another disadvantage of the three-level PFC is the output capacitor voltage imbalance. This thesis proposes an active balancing solution to solve this problem. / Master of Science

Functional electrical stimulation (FES) devices have direct applications in the realm of rehabilitation engineering, physiotherapy, occupational therapy and medicine for research, diagnostic and therapeutic purposes. This thesis presents a novel electrical stimulator for use in a FES system. The stimulator produces regulated current pulses using two switched mode power supplies (SMPS) in series. The first power stage - a flyback converter - steps up the supply voltage using primary side digital control. The second power stage is a buck converter with output current hysteretic control. An output switched capacitor circuit shapes the current pulses. All pulse variables are programmable and various pulses can be formed for virtually any FES application. Compared to previous FES devices, the pulses generated here are sharper, have faster rise time and the amplitude and temporal characteristics are more tightly regulated. A single channel prototype system is implemented and experimental results are shown.

Functional electrical stimulation (FES) devices have direct applications in the realm of rehabilitation engineering, physiotherapy, occupational therapy and medicine for research, diagnostic and therapeutic purposes. This thesis presents a novel electrical stimulator for use in a FES system. The stimulator produces regulated current pulses using two switched mode power supplies (SMPS) in series. The first power stage - a flyback converter - steps up the supply voltage using primary side digital control. The second power stage is a buck converter with output current hysteretic control. An output switched capacitor circuit shapes the current pulses. All pulse variables are programmable and various pulses can be formed for virtually any FES application. Compared to previous FES devices, the pulses generated here are sharper, have faster rise time and the amplitude and temporal characteristics are more tightly regulated. A single channel prototype system is implemented and experimental results are shown.

This master’s thesis work deal with diagnosis parameters immunity curves uniphase appliance on short - term voltage dips a interuption. Immunity curve is dependence smallest possible sizes RMS voltage for performance given to criteria function on time continuation voltage event. Curves of resistance is different for each electric appliance, and depending on the size and over-voltage network, the burden on resources and voltage during the event.. The goal of this work is to devise a methodology for measuring the implementation of parametric measurement limit curves of resistance for selected types of appliances.

In this thesis a multifunctional DC/DC converter board will be developed for utilization as an educational experiment set in the switched-mode power conversion laboratory of power electronic courses. The board has a generic power-pole structure allowing for easy configuration of various power converter topologies and includes buck, boost, buck-boost, flyback, and forward converter topologies. All the converters can be operated in the open-loop control mode with a switching frequency range of 30-100 kHz and a maximum output power of 20 W. Also the buck converter can be operated in voltage mode control and the buck-boost converter can be operated in peak-current-mode control for the purpose of demonstrating the closed loop control performance of DC/DC converters. The designed board allows for experimentation on the DC/DC converters to observe the macroscopic (steadystate/ dynamic, PWM cycle and low frequency) and microscopic (switching dynamic) behavior of the converters. In the experiments both such characteristics can be clearly observed such that students at basic learning level (involving only the macroscopic behavior), and students at advanced learning level (additionally involving the parasitic effects) can benefit from the experiments. The thesis reviews the switch mode conversion principles, gives the board design and proceeds with the experiments illustrating the capabilities of the experimental system.