Demand and supply of energy - smart power conversion not only for lighting: Presentation held at 10th Seminar on Power Electronics and Control, SEPOC 2017, Santa Maria, Brazil, 22-23 October 2017

Energy is becoming a scarce good, although regenerative sources are growing. The main potential for future energy management is not first of all to generate more energy but to save energy by intelligent control wherever possible. The costs of smart control for energy saving are becoming smaller than the energy cost savings themeselves. An example for lighting, based on the efficiency of LEDs, even being already much more efficient than the „good old light bulb“, shows that intelligent control of light is feasible on smaller expense for customers than traditional illuminants with manual switches. The upcoming „Internet of Things“ will support smarter solutions that have not only more functionality, but also great benefit in costs. Low-cost sensors, energy harvesting, digital control, and even highest integration of power supplies will not be obstructive to provide energy saving based on growing intelligence of control. Decentralized control structures with local wireless communication, additionally to cloud computing and internet-based communication will provide increasing opportunities to attract energy customers to interact with energy providers and energy distributors for lower costs on all hands

Digital control for off-line power supplies using digital platform DP2: Presentation held at International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy Management, 5 - 7 June 2018, Nuremberg, PCIM Europe 2018

Digital control for off-line power supplies becomes competitive to analogue control. Costs for hardware changes and several PCB versions for an analogue controller product family will be larger than for digital controllers that can modify functionality by different program versions using one hardware design. Further, a digital UART interface of a digital controller platform simplifies the option for an upcoming demand on intelligent network as IoT, including the power supply itself. IoT will cause request of parameter feedback from power supplies as load profile or fault events

Normalized State-Space Models for Resonant Rectifiers

In AC-DC power conversion, the input source features: time dependence and phase angle, combined with the complexity of resonant circuits, lead to solutions that are difficult to obtain. In this sense, an analysis and design methodology of resonant rectifiers is proposed, in which, iterative numerical solutions are replaced by analytic solutions with the help of computer algebra systems. The method allows obtaining the AC-to-DC transfer function, the quality factor, the phase angle and the resonance frequency. A case study for the Class-E zero-derivative voltage switched resonant rectifier is performed. Experimental results are shown in order to validate the theoretical approach

Ultrasound Piezo-Harvester Energy Transfer Systems for MachineTool Sensor-Charger Applications

Ultrasound energy transfer systems can be an alternative for sensor-chargers aiming batteryreplacement avoidance and can be used in machine tool applications. An ultrasound input source canbe used to send an acoustic signal through a machine. The signal is received by an ultrasound receiverbased on piezoelectric component and should be converted into an electrical signal to supply or chargethe sensor. Notwithstanding, for rotating machines, an air gap must be considered between the inputsource and the machine tool part. This paper deals with the acoustic-electrical energy transferconsidering the changes in the propagation media of the ultrasound. Theoretical results are verified bymeans of an experimental setup

Energy harvesting and conversion - applications of piezoelectric transformer and transducer MEMS: Presentation held at IFAAP 2018 - Session 31am-A05-Energy Harvesters, ISAF-FMA-AMF-AMEC-PFM (IFAAP) Joint Conference in Hiroshima, May 27th - June 1st, 2018

A systematic investigation of the feasibility to integrate complete piezo-based power supply on silicon was done. Up to now, fully integrated off-line power supplies on chip are available as products for below 1 Watts. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated as MEMS when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more, but unfortunately on the cost of significant large chip area. However, piezoelectric transformers will gain higher acceptance in power converters if a magnetic-field-free environment is requested as for magnetic resonance tomography. Promising piezoelectric applications can be found for transformer-transducer units to harvest ultrasonic energy, preferably in medical therapy-diagnosis applications, but further, in industrial autonomous sensor supplies with avoidance of electromagnetic disturbance. Piezoelectric energy harvesting becomes attractive using ultrasonic energy harvester MEMS with wide range frequency excitation using permanent magnet cantilever construction. Ultrasonic MEMS loudspeakers are miniaturized alternatives to traditional magnetic devices. The advantage of piezoelectric MEMS applications will result in an extreme miniaturization compared to conventional power conversion by magnetic or electrostatic solutions. High reliability including intelligent integrated functions in some cases may improve the practicability of piezoelectric MEMS

Miniaturization of power converters by piezoelectric transformers - chances and challenges: Presentation held at International Symposium on Piezocomposite Applications, ISPA 2017, September 13 - 15, 2017, Fraunhofer IKTS Dresden

A systematic approach of the feasibility to integrate complete piezo-based power supply on silicon is the focus of research activities within Fraunhofer EAS, ISIT an IZM. Up to now, fully integrated off-line power supplies on chip are available for below 1 Watts, e.g. from Texas Instruments. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. The driving topology can be formed by high-voltage Mosfets or multi-level low-voltage Mosfet topology based on SOI or GaN on Si and integrated micro-inductors in the future. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more. Synchronous rectifying devices can be formed by low-voltage Mosfets at the output stage of the power supply. The advantage will be an extreme miniaturization compared to discrete power supplies, reduction of blocking capacitors by interleaving techniques, and thus, high reliability including intelligent integrated functions as stabilization circuits, sensors or control

Modeling and Design of a Linear-Assisted Zeta Conveter

Linear-assisted switching (PWM) converters have advantages over single switching topologies, mainly because of the reduction or elimination of bulky output capacitors and ultra-fast dynamical response. In this paper, a linear-assisted zeta converter is presented. The linear regulator circuit is composed by three bipolar transistors and an operational amplifier, which drives the transistor based on the error between the output voltage and its reference. The modeling of the whole circuit is presented, as well as a design example. The modeling of the zeta converter is similar to the conventional topology modeling, except the fact that the linear regulator current is considered as an extra state that substitutes the state regarding the output capacitor voltage. The zeta converter can be designed independently of the linear regulator circuit and simulations are used to validate the static operation of the overall topology. Experimental results confirm in practice the ripple compensation of the main zeta converter, where extra current is provided by the main converter, in order to drive the linear regulator that is responsible for the ripple compensation