Academic literature on the topic 'Series parallel resonant converter'

A power supply incorporating a series-parallel load-resonant converter, capable of very efficient operation over a wide range of output power is presented. The series-parallel load-resonant converter is shown to have three pairs of resonant frequencies. Operation of the circuit at each of these resonant frequencies maintains zero current switching and high frequency operation. Design mathematics is developed which allow series-parallel load-resonant converters to be designed with specific resonant frequencies and circuit resistances. A new method of power control for series-parallel load-resonant converters is presented; the power delivered to the circuit and hence the load is shown to var substantially depending on which resonant frequency the circuit is excited at. Two series-parallel load-resonant converters are designed simulated, constructed and tested. There is good agreement between the simulation and experimental results. One of the circuits produces an output current of 200 A while the second demonstrates the new power control technique pulsing between 55 A and 145 A while running at frequencies of 63 kHz and 100 kHz. The new power supply is particularly suited to arc-welding. It contains an active rectifier and draws near unity power factor.

The project deals with the design of a switch-mode power supply (SMPS) with a medium and high power output. The power supply uses multiphase control switching. Electric energy is converted through a series parallel LLC resonant circuit to reach the maximum efficiency with a small size and cost efficiency of the designed power supply. The semiconductor switches use ZVS (Zero Voltage Switching) on the primary side and ZCS (Zero Current Switching) on the secondary side of the converter. The design of the converter is based on the knowledge of the high power output converters (types of switching, art topologies) and resonant topologies (series resonant circuit – SRC, parallel resonant circuit – PRC and series parallel circuit –SPRC). The design of the converter was done theoreticaly and tested by using simulation program. The simulation and partial tests served to build prototype the Interleaves Converter (ILLC). The function of the converter was tested in laboratory. The laboratory results have been compared with the theoretical and the simulation results.

A converter is proposed which is based on <i>parallel-resonant</i> technology, incorporating a capacitive filter. The convertor complies with a high-power, low voltage load specification, and is required to operate with a fixed switching frequency. The topology uses a combination of resonant tanks, and a clamped voltage technique, to maintain the advantages of more standard square-wave converters, whilst exploiting the desirable features of resonant conversion. The purpose of the proposed converter is threefold: 1. -to reduce the converter size by operating without an output filter choke; 2. -to reduce component stresses by clamping internal voltages, and so limiting voltage and current peaks; 3. -to reduce switching losses by limiting the volt-current product during the switching transient. The shape of the internal waveforms define the power transferred and are determined by values of resonant components positioned within a standard bridge circuit. As a result of these resonant components the converter efficiency at full load approaches 93%, and the characteristics of the EMI spectrum are favourable. Low power resonant techniques are well understood, however, operation at higher output powers requires careful construction techniques and consideration of various engineering compromises. An explanation of these is presented and justification for their choice is discussed. Three prototype converters are built and tested, and problems encountered during their development are highlighted. Results of two simulation techniques correlate well with the observed results, and a numerical modelling technique is developed as a design aid. As a result of the work at low output voltages it is shown that the converter is better suited to operation as the front-end of a <i>distributed power</i> power system, converting voltage from 270 V to 48 V.

Primarily because of its low cost and ease of implementation, analogue control has been the dominant control strategy in modern switch-mode power supply designs. The 'on/off' nature of power switches is essentially digital, which makes it tempting for power elec- tronics engineers to combine the emerging capability of digital technologies with existing switch-mode power supply designs. Whereas an analogue controller is usually cheaper to implement, it lacks the flexibility and capacity to implement the complex control func- tions which a digital controller can offer. The research presented in this thesis addresses the practical implementation of a digi- tal controller for a Series-Loaded Resonant Converter (SLR). The resonant frequency of the SLR converter is around 60 kHz, and the switching frequency varies up to around 80 kHz to regulate the 12V dc output voltage across a 100W, variable resistive load, from a variable 46.6V 60.2V input voltage. This provides a fair challenge for digital waveform generators as the digital processor needs to have a high clock rate to produce high speed, high resolution and linearly varying frequency square waves, to regulate the output volt- age with adequate resolution. Digital compensation algorithms also need to be efficient to minimise the phase lag caused by the instruction overhead. In order to completely understand the control needs of the SLR converter, an analogue controller was constructed using a UC3863N. The feedback compensation consists of an error amplifier in an integrator configuration. Digital control is accomplished with a TMS320F2812 Digital Signal Processor (DSP). Its high throughput of 150 MIPS provides sufficient resolution to digitally generate linearly varying frequency switching signals util- ising Direct Digital Synthesis (DDS). Time domain analysis of the switching signals, shows that the DDS generated square iv ABSTRACT waves display evidence of jitter to minute variations in pulse-widths caused by the digi- tisation process, while in the frequency domain, this jitter displays itself as additional sidebands that deteriorate the fundamental frequency of the switching signal. Overall, DDS generated square waves are shown experimentally to be adequate as control signals for the MOSFET power switches. Experiments with step load changes show the digi- tal controller is able to regulate the output voltage properly, with the drawback of the settling time being a little longer than the analogue counterpart, possibly caused by the unpredictable damping effects of switching signal jitter. Variations in input voltage shows that the digital controller excels at operating under noisier conditions, while the analogue controlled output has slightly greater noise as input voltage is increased. As the digital technology continues to improve its speed, size and capacity, as well as becoming more affordable, it will not be long before it becomes the leading form of control circuitry in power supplies.

The inherent difficulty in designing high voltage power supplies is often compounded by demands of high reliability, high performance, and safe functionality. A proposed high step-up ratio DC-DC converter meets the exacting requirements of applications such as uninterruptible power systems, radar, and pulsed power systems. The proposed DC-DC converter topology combines a multi-phase buck input stage with a novel self-tracking zero-voltage-switching (ZVS) resonant output stage. Traditionally, the inclusion of multiple power processing stages within a power supply topology severely degrades the overall converter efficiency. Due to the inherent high efficiency per stage, however, this effect is minimized. The self-tracking switching scheme ensures that ZVS occurs across the full range of load variation. Furthermore, the switching scheme allows significantly increased flexibility in component tolerances compared to traditional resonant converter designs. The converter also demonstrates indefinite short-circuit protection and true ZVS during transient processes. Computer simulation and hardware analysis verify the efficacy of the topology as a rugged and efficient converter.

A brief analysis of the nonresonant-coupled parallel resonant converter is performed. The converter is modeled and a reference classical analog controller is designed and simulated. Infrastructure required for digital control of the converter (including anti-aliasing filters and a modulator) is designed and a classical digital controller is designed and simulated, yielding a ~30% degradation in control bandwidth at the worst-case operating point as compared with the analog controller. Based on the strong relationship observed between low-frequency converter gain and operating point, a gain-scheduled digital controller is proposed, designed, and simulated, showing 4:1 improved worst-case control bandwidth as compared with the analog controller. A complete prototype is designed and built which experimentally validates the results of the gain-scheduled controller simulation with good correlation. The three approaches that were investigated are compared and conclusions are drawn. Suggestions for further research are presented.<br>Master of Science