Electronic filter

About: Electronic filter is a research topic. Over the lifetime, 13207 publications have been published within this topic receiving 93063 citations. The topic is also known as: filter.

Energy efficient DC-grids for commercial buildings

Abstract: Modern power electronics enable the efficient supply of almost all kinds of electric applications in commercial buildings, e. g. lighting, ITand telecommunication equipment, as well as speed-controlled drives in heating, cooling and ventilation applications. This potential can be used more effectively using a 380 VDC Grid compared to a traditional AC Grid in commercial buildings. The European ENIAC R&D project consortium DC Components and Grid (DCC+G) is developing suitable, highly efficient components and sub systems for 380 VDC grid to show the benefits of DC grid concept on test site in an office environment. The newly developed DC Grid components and their integration into a generic system are presented in this paper. The targeted overall efficiency saving compared to AC grid is 5% and the energy conversion from PV is calculated to be 7% higher compared to traditional PV inverter conversion. This paper also shows the layout of the office demonstrator at Fraunhofer Institute in Erlangen, Germany, and describes general benefits of a DC Grid system. I. POTENTIAL OF MODERN POWER ELECTRONICS IN DC GRIDS In the last decade research and development work in the field of power electronic semiconductor lead among other things to following improvements:  Significant reduction of conduction losses (RDSON) in power electronic devices, through technologies like Trench MOSFET technology [1], super junction technology [2], [3] and upcoming technologies like Multiple Epitaxy and Deep Trench [4].  Steadily increasing switching performance and reduction of parasitic capacitances in power electronic devices.  Application of new devices on basis of wide band gap semiconductor materials (SiC and GaN) with advanced switching and temperature performance [5]. An important benefit of the new ultra-fast switching devices is the possibility to increase the operation frequency in the power electronic circuits and shrink down passive components size to get higher power density in many applications. This lead also to a reduction of the application costs because the passive component size is correlated to the costs. These trends and the improvements in power density and efficiency over the last years in the research and industry area are described in [6]-[9]. As an example, a switch mode power supply for a flat TV screen is shown in figure 1. According to [10], [11] approximately 50 % of losses, 70% of weight and 70 % of volume are necessary for the rectifier, EMI filter, power factor correction and DC link storage. This means that most of the cost, volume and efficiency of the power supply is wasted in the AC line front-end with the only task to provide a DC (link) voltage. The really bad story is that we do this in almost every electronic device. Several times on an office desk, in driver for LED lamps and in many consumer electronics. Figure 1: Different parts of a typical power supply for a flat TV as described in [10] and [11]. In more and more applications it is possible to develop integrated power electronic solutions. Moore's law predicts the number of transistors in a dense integrated circuit doubles approximately every two years. Integrated power electronic circuit can benefit from these improvements in semiconductor technologies. But in applications connected to a 50 Hz or 60 Hz AC grid, line frequency is fixed and the size of the passive filter components, power factor correction circuit and link capacitor cannot be further reduced. In that circuit area (marked red) there is only a small volume benefit through new faster switching devices and the usage of new semiconductor materials. GaN devices (25A/100V) allow switching frequencies up to 10 MHz with 89% efficiency in size of a SO-8 package [12]-[14]. Optimized GaN driver and control circuits can provide efficiency up to 93 % [14]. This means, that the blue marked area in figure 1 will be dramatically decrease in volume and costs over the next years. DC micro grids can use the benefits of the new fast switching power electronic devices especially in power density, cost and efficiency issues. There is a trade of behavior between these three factors which allows the individual optimization for the applications. II. THE RIGHT VOLTAGE LEVEL ETSI EN 300 132-3-1 standard specifies a voltage range from 260 VDC to 400 VDC for a new DC interface for ICT equipment in telecom and data centers [15]. This wide voltage range has been selected with regard to power systems equipped with batteries. Nominal operating voltages in telecom and data centers are 354 VDC and 380 VDC, but when outage occurs, the battery voltage drops down to 260 VDC. However, variable battery voltages can be easily stabilized with a DC/DC converter. That is why DCC+G consortium has selected 380 VDC ± 20 V voltage range for 380 VDC loads and ±380 VDC with ±20 V tolerance for 760 VDC loads. This is a good compromise between highest achievable efficiency, available power semiconductors, compatibility with ETSI EN 300 132-3-1 and already existing power supplies for AC grids. III. SWITCHED MODE POWER SUPPLY (SMPS) Many applications in office environments operate with DC voltages equal or lower than 24 V, like computers, laptops, monitors, and printers. A rectifier, PFC stage and an isolating DC/DC converter (e.g. resonant (LLC) or Flyback type) are typically used to convert AC mains voltage into save low DC supply voltages. A two stage topology for AC/DC adapters as shown in figure 2 and described in [16] can be divided into the AC rectifier and PFC stage forming the AC line front-end, and a DC/DC converter for generating the application specific extra low voltage. The line frontend generates a stable output voltage in the range of 380 VDC. The second part provides the application voltage, for example 24 VDC. Figure 2: Different circuit blocks of a typical switch mode power supply to provide a voltage of 24 V. One basic concept of the proposed 380 VDC grid is to centralize the AC line front-end (filter, rectifier, and power factor correction), i.e. each application device only needs the second stage (DC/DC converter). The central front-end for many devices can be more complex and more efficient because of higher power flow through it and it can also benefit of statistical and scale effects. Overall, this saves energy, costs, and material because the central rectifier can be optimized on a higher performance level compared to a small cost sensitive single AC/DC adapter. In addition, a large central rectifier can be designed to provide a variable power factor that would be too expensive for cost sensitive applications. Another optimization can be the efficiency. The efficiency of the frontend converter in figure 2 is typically 95 %. The central rectifier of the DCC+G Project achieves an efficiency up to 97% over a wide load range [17]: i.e. 2% efficiency improvement with less electronic and costs in the application. Low cost line adapters for external hard disks, mobile phones, battery chargers, USB hubs, and routers mostly have much lower efficiency in the range of 50-80 % [18]. For comparison, nonisolating DC/DC converters (24 V / 5 V) easily achieve efficiencies of 90-98 %, insulating DC/DC converters (380 VDC / 24 V) efficiencies of 90-95 %. Buildings which already have a photovoltaic system and/or battery storage installation have already a DC bus. So if there are sources that provide energy direct on the 380 VDC grid the frontend losses of approximately 5 % can be avoided completely. IV. OPTIMAL EMI FILTER DESIGN FOR 380 VDC Filter circuits for AC grid connected devices are optimized to comply with conducted emission requirements related to standards for the product that is selected. For IT/ICT equipment such a standard is IEC/EN 55022 and for lighting systems it is IEC/EN 55015. In the scope of DCC+G our goal is to provide at least the same DC Grid quality as on the AC side, so we specified the same EMI requirements for the DC grid. As an example, a fluorescent lamp ballast is considered, with a similar topology as shown in figure 2. Instead of the DC/DC converter, the second stage is a resonant high frequency (50 kHz) DC/AC inverter in this application. To characterize the EMI behavior we directly connected the DC/AC inverter of the lamp ballast to the 380 VDC grid. Then measurements according to IEC/EN 55015 have been done [19]. Several measurements with different configurations of the driver have been made. The reference measurement was done on the complete AC circuit without the frontend filter. This is compared with the DC case where only the second stage (resonant DC/AC inverter) was used. These two cases are shown in figure 3. It can be seen that in the lower frequency range below 80 kHz the conducted noise voltages in the DC case are up to 40 dBμV lower as in the AC case. In the medium frequency range up to 3 MHz the DC case shows an approximately 10 dBμV higher noise level than the AC case. In the higher frequency range the DC case again shows better EMI properties. The necessary DC-filter has to be optimized for higher middle frequency and a smaller bandwidth compared to the AC-filter. A filter for higher frequencies results in smaller foot print and less attenuation requirement. Thus the effort of such DC grid filter will be lower than for an AC grid filter. Reference [20] mentions that a typically EMI input filter utilizes capacitors to provide a low impedance shunt path for high frequency currents. So such capacitors must be able to shunt current over a wide frequency range. To achieve this, various types of capacitors are placed in parallel. Large capacitance electrolytic capacitors are used to shunt lower frequencies and provide voltage holdup. For mid-range frequencies typical X-type and Y-type film and ceramic capacitors are employed [21]. Figure 3: AC grid (blue) and DC grid (red) EMI behavior of a fluorescent lamp driver without filter (situation before filter

Integration of high-Q BAW resonators and filters above IC

Abstract: A double-lattice BAW filter with balanced input and output is designed with a center frequency of 2.14GHz. The filter is integrated directly above a 0.25/spl mu/m BiCMOS RF IC. Insertion loss of -3dB and out-of-band rejection better than -50dB are achieved. An integrated LNA comprising two broadband amplifiers and one BAW filter is also presented.

Integrated Bandpass Filter at 77 GHz in SiGe Technology

Abstract: The implementation and characterization of an integrated passive bandpass filter at 77GHz is presented. A lumped elements filter occupying very small die area (110times60mum2, without pads) is demonstrated. It is realized with spiral inductors and metal-insulator-metal capacitors. The filter is fabricated in an advanced SiGe:C technology. It has a center frequency of 77.3GHz and a bandwidth of 12GHz. The insertion loss is 6.4dB. This is the first time that integrated inductors are used for filters at millimeter wave frequencies around 80GHz

An optimization based method for selection of resonant harmonic filter branch parameters

Abstract: Resonant harmonic filters (RHFs) are effective devices for reducing supply current harmonics when only those load generated harmonics for which they are tuned are present. Other current harmonics as well as supply voltage harmonics may reduce the effectiveness of RHFs in harmonic suppression. To counter such reductions in effectiveness, an optimization based method for selection of filter branch parameters is developed for the conventional RHF. It takes into consideration the interaction of the filter with the distribution system and provides filter parameters that give the maximum effectiveness with respect to harmonic suppression. To accomplish this, a cost function is developed, its behavior examined, and appropriate constraint functions are developed. The results for optimized filters, applied in a test case, are given.

A Low THD, Low Power, High Output-Swing Time-Mode-Based Tunable Oscillator Via Digital Harmonic-Cancellation Technique

Abstract: An architectural solution for designing and implementing low THD oscillators is presented. A digital harmonic-cancellation-block is used to suppress the low-frequency harmonics while a passive, inherently linear, filter is used to suppress the high-frequency ones. The proposed technique eliminates the need for typical high-Q BPF to suppress the harmonics. Thus, eradicates the effect of increasing device nonlinearities in the nanometric technologies by having pure digital solution. In addition, eliminating the need for high-Q band-pass-filter (BPF) releases the output swing from the constraints imposed by the linearity of the filter. The prototype is fabricated in 0.13 ?m CMOS technology. Measurement results show -72 dB THD at 10 MHz along with a differential output swing of 228 mVpp. The oscillator prototype can be tuned from 5 MHz to 11 MHz with less than 4.5 dB variations in the THD. The circuit consumes 3.37 mA from 1.2 V supply at 10 MHz and occupies an area of 0.186 mm2. As the performance depends solely on the timing precision of digital signals, the proposed oscillator is considered the best time-mode-based oscillator in literature.