397 results about "Passive power filter" patented technology

A soft-switched single-phase quasi-single-stage (QSS) bi-directional inverter/charger converts AC-DC or DC-AC. The inverter/charger comprises a push-pull inverter/rectifier on the dc-side, an isolation transformer which provides ohmic isolation and voltage scaling, two full-bridges on the ac side in cascade, a voltage clamp branch comprising a capacitive energy storage element in series with an active switch with its anti-parallel diode, a passive filter at the ac side to smooth out the high frequency switching voltage ripple at the output, and a corresponding PWM scheme to seamlessly control the converter to operate in all four quadrant operation modes in the output voltage and output current plane, and is capable of converting power in both directions.

In one embodiment of an optical pointing device, an illumination system includes a plurality of light sources. Each light source is characterized by a unique set of illumination characteristics. Illumination characteristics include impinging angle, light wavelength, light homogeneity, and the like. A sensor receives electromagnetic energy originating at the light source to scan an imaged area. The sensor measures performance indexes associated with the light sources, which depend on the illumination characteristics. The sensor includes an imaging module, which may include passive filters, and control logic, which includes at least a DSP module and a light sensor selection module. Another embodiment includes additional signaling light sources that do not interfere with the illumination system and are for signaling to the user. A method to select the most adequate light source for any given surface is based on measured performance indices.

A method for implementing an inductor-capacitor filter in an integrated circuit. Embodiments of the invention implement a 5-pole LC low-pass filter suitable for incorporation in wireless applications necessitating compact layouts. Inductors are formed in an IC as concentric coils on metallization layers, the concentric coils providing a negative coupling coefficient between the inductors. The invention provides programmable frequency response characteristics, enabling the transmission of high-frequency base band information while attenuating carrier RF frequencies.

An amplifier having an active and passive gain stage connect to a load for driving a load according to a system analog input. A first embodiment of the amplifier in accordance with the present invention includes a logic network connected between a comparator network and a switching system, wherein the comparator network connects to the passive gain stage. Specifically, the active gain stage may include an active filter connected to receive an analog or digital input and provide a difference between the analog or digital input and the feedback signal relative to the gain factor of a gain unit connected to the active filter. The passive gain stage includes a passive filter. The logic network generates at least one switching signal which controls the switching system that includes at least one switching device to selectively provide power to the load. An output signal from the switching system provides output for the amplifier and is fed back to the active gain stage. In another embodiment, the output is a two-level signal and the passive and active filters are second order low pass filters, where the gain factor is about 25 or more. In yet another embodiment, the gain factor is approximately 250. Moreover, the amplifier may include a digital delta-sigma modulator connected to supply a two level input.

In EMI filter assemblies incorporating one or more passive filter elements including feedthrough capacitors and lossy ferrite inductors, a process is provided for tuning the various components to reduce the amount of heat generated in implanted lead wires during medical procedures such as magnetic resonance imaging. The process includes selection and testing of individual components and an interative process involving tradeoffs and subsequent testing prior to finalization of the feedthrough design.

A fourth order delta sigma analog-to-digital converter is presented, comprising a passive delta sigma modulator including a passive filter, a quantizer, and a digital-to-analog converter in a first feedback loop, and an active filter having a large gain factor in a second feedback loop around the passive delta-sigma modulator.

A hybrid conditioner for filtering harmonics in a power system that includes a non-linear load. The hybrid conditioner includes an active filter structured and controlled to filter one or more high-order harmonic currents of the fundamental frequency, and a passive filter structured to filter one or more low-order harmonic currents of the fundamental frequency. The active filter and the passive filter are electrically connected in parallel with one another. The hybrid conditioner may also be for providing reactive power compensation for the power system, wherein the active filter is further controlled to provide a compensatory reactive power for compensating for the reactive power that is consumed by the load. The hybrid conditioner may also provide oscillation dampening for the power system, wherein the active filter is further controlled to damp oscillating currents that exist between the passive filter and the AC source.

The present invention provides a high brightness color selective light modulator (CSLM) formed by a polarization modulator positioned between two retarder stacks. The modulator changes the apparent orientation of one retarder stack relative to the other so that, in a first switching state of the modulator the two retarder stacks cooperate in filtering the spectrum of input light, and in a second switching state the two retarder stacks complement each other, yielding a neutral transmission spectrum. Two or more CSLM stages can be used in series, each stage providing independent control of a primary color. One preferred embodiment eliminates internal polarizers between CSLM stages, thereby providing an additive common-path full-color display with only two neutral polarizers. Hybrid filters can be made using the CSLMs of this invention, in combination with other active or passive filters. The CSLMs of this invention can be used in many applications, particularly in the areas of recording and displaying color images. They can be arranged in a multi pixel array by pixelating the active elements, and can be implemented as color filter arrays, using patterned passive retarders rather than active polarization modulators.

A filter enhancer provides greater performance in a passive filter. The passive filter has an input terminal for receiving a signal in a first frequency band and an output terminal for providing a signal in a second frequency band. The filter enhancer includes: (a) a first canceller circuit coupled between input terminal and output terminal, the first canceller circuit including a first finite impulse response (FIR) filter for attenuating signals in the first frequency band; and (b) a control circuit coupled to output terminal and first canceller circuit for providing adaptive coefficients for configuring the first FIR filter. The first FIR filter may be implemented by either a digital FIR filter or an analog FIR filter. The filter enhancer may further include a second canceller circuit coupled between input terminal and output terminal, the second canceller circuit including a second FIR filter for attenuating signals in the second frequency band.

The invention discloses a method for enhancing the non-uniform variation grid width of the light load efficiency of an integrated switch DC-DC converter, a Buck-Boost converter in the invention adopts the design of a CSMC 0.5mu m CMOS process library, whole-circuit integration is realized except for a passive filter, the external filter inductance is 2.2mu H, and the filter capacitance is 1mu F. According to the requirements of input voltage and output voltage, the converter can work in three modes: Buck (voltage reducing), Buck-Boost (voltage reducing and boosting) and Boost (voltage boosting), the range of the input voltage is 2.5V-4.2V, the range of the output voltage is 1.5V-5V, and the working frequency is 5MHz. A non-uniform grid width modulation method is adopted in the whole load current range of 10mA-650mA. When the converter works at high frequency of 5MHz, the efficiencies of medium load and heavy load keep above 90 percent all the time, and the efficiency of light load (10mA) can reach above 80 percent. As the grid width of a switching tube is only changed and a control link of the working efficiency of an extra switching tube is not adopted, negative effects caused by frequency conversion control are eliminated fundamentally.

The invention discloses a joint operating system of the static var compensator and active power filter and the control method, which is characterized in that an active power filter and a control device are added in the static var compensator. The control method of balance compensation of three-phase unbalanced loads is used to realize the compensation of load negative sequence current and the technology of specific subharmonic compensation is used to realize the decoupling control of SVC and APF, so as to guarantee the safe and stable operation of the joint operating system. The invention notonly has the basic functions of the SVC, but also improves the filtering performance of the passive filter through APF, suppresses possible resonance phenomena between the passive component and the power grid equivalent impedance, and can realize dynamic management on subharmonic waves.

The invention discloses a filter device for controlling a harmonic wave of an electric power system. The device comprises a passive filter and an active filter, wherein the passive filter comprises a quintic harmonic wave filter branch circuit, a septic harmonic wave filter branch circuit, and an eleventh harmonic wave filter branch circuit, which are connected in parallel; each harmonic wave filter branch circuit comprises a breaker, a current transformer, a fuse protector, an electric reactor, a capacitor and a bidirectional thyristor which are sequentially connected in series; the active filter comprises a first resistor and a second resistor; the first resistor is connected to a low voltage side of a power grid transformer in series; the second resistor is connected to the other side of the first resistor in parallel; the other end of the second resistor is connected with a base of an insulated grid bipolar transistor; the capacitor is connected between a collector and an emitter of the insulated grid bipolar transistor in parallel; each harmonic wave filter branch circuit of the passive filter and the input end of the active filter are connected to the low voltage side of the transformer in parallel; the output end is connected with the load; and the high voltage side of the transformer is connected with the power grid. The device can remove the harmonic wave, and can achieve the targets of saving energy and reducing emission at the same time.

A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

The invention relates to an active power quality adjuster, consisting of a fundamental wave compensation part and a harmonic wave compensation part, and the two parts compensate fundamental current and harmonic current respectively. An H-bridge cascade multilevel inverter and a fundamental wave connection inductance are connected in series at the fundamental wave compensation part, so that reactive compensation and unbalanced load compensation can be dynamically carried out; the H-bridge cascade multilevel inverter and a unituning passive filter are connected in series to form the harmonic wave compensation part which is connected across the two ends of the fundamental wave connection inductance. Therefore, the power quality adjuster can lower switching frequency and loss of the H-bridge cascade multilevel inverter at the fundamental wave compensation part greatly on one hand, and only a fraction of fundamental current passes the harmonic wave compensation part and the whole part only undertakes fundamental voltage of the fundamental wave connection inductance without undertaking fundamental voltage on the other hand, thereby effectively reducing the capacity of the H-bridge inverter and the withstand voltage at the harmonic wave compensation part.

The invention relates to methods for distributing the reactive power compensation capacity and switching branch circuits of a passive filter. In the method, the passive filter is provided with a plurality of filter branch circuits; and each filter branch circuit consists of a switching relay, a capacitor, a resistor and a reactor. The method for distributing the reactive power compensation capacity of the passive filter comprises the following steps of: calculating a total reactive power compensation quantity; calculating the compensation capacity of the filter branch circuits; and calculating element parameters of the respective filter branch circuits. The passive filter designed by using the method for distributing the reactive power compensation capacity of the passive filter performs reactive power compensation and filter suppression, and the reactive power compensation capacity of the respective filter branch circuits compenhensively considers a load running characteristic and harmonic source current, so that the compensation quantities of the filter branch circuits are more reasonable; therefore, the passive filter can run more flexibly and has higher dynamic compensation property.

The invention discloses a mixed induction type active electric power filter system. The mixed induction type active electric power filter system comprises a rectifier transformer, a filtering branch, a rectifier and the other filtering branch, wherein the other filtering branch comprises three passive filters and a voltage source inverter, the passive filters are connected to the voltage source inverter, the primary side of the rectifier transformer is connected to a three-phase power grid through connecting impedor, an epitaxy winding of the secondary side of the rectifier transformer is connected with the rectifier, and the passive filters are connected to three junction points between a delta winding and the epitaxy winding of the secondary side of the rectifier transformer in parallel respectively. According to the mixed induction type active electric power filter system, influence of frequency fluctuation of the power grid side and the high-capacity nonlinear load side on electric power filtering performance is eliminated; meanwhile, the problems that serious harmonic pollution, high additional loss of a master device, high vibration and noise, low system power factor and low system operation efficiency are caused by harmonic waves and idle work to an industrial power distribution and consumption system are effectively solved on the premise that electric power quality on the power grid side meets the national standard of China.

The invention discloses a device used in an electrified railway for controlling and compensating electric energy quality, and belongs to the field of power supply of electrified railways. The device comprises a passive filter formed by a second-order high-pass filter, a group of voltage source type converters, and a phase reactor, wherein the passive filter is used for providing an electric locomotive on an electrified railway with reactive power and filtering harmonic current generated by the electric locomotive; the voltage source type converters can generate voltage with controllable amplitude, phase and frequency and are used for negative sequence compensation, flicker control and the like of a traction power supply system of an electric railway; and the voltage source type converters are connected in parallel onto a 25kV traction electric network through the phase reactor and the passive filter. The device provided by the invention can solve the electric quality problems such as three phases imbalance, harmonic wave, voltage fluctuation, flicker and the like while compensating power factors of the power supply system of the electric railway. Additionally, with the fully play of the advantages of the passive filter, such as convenience for configuration and low cost, and the advantages of the voltage source type converter, such as small occupation area and low consumption as much as possible, the whole set of device can achieve the best technical specification and the greatest economic performance.