640results about How to "Reduce Harmonic Distortion" patented technology

A power converter for converting energy from a green power unit as e.g. a solar cell into energy fed into the commercial grid is described. The object is to provide a versatile modularized power converter with eased access to control of the power switches. Another object is to improve the electrical efficiency. This is achieved by using an independent controller on a DC/DC module and an independent controller on a DC/AC module, whereby the the two independent controllers communicate with each other and the outside world by means of a communication bus. Further, the DC/DC module of the power converter comprises a transformer which transfers energy from the DC/DC module to the DC/AC module. This design enables independent control of the modules and eases controllability of the power switches in order to suppress retroaction from pulsations generated on the mains when supplying energy to a single phase grid. Hereby the electrical efficiency of the power converter is increased. Also, an active snubber circuit is described which further increase the efficiency.

An active power factor correction (PFC) circuit and its controlling method are provided. The method comprises the following steps. Drive the power switch of the circuit so that the average inductor current waveform follows the rectified input voltage waveform. Suspend the operation of the power switch at a first moment in a first line cycle of the rectified input voltage and then resume the operation of the power switch at a second moment in a second line cycle of the rectified input voltage. The first moment is when the phase angle of the rectified input voltage exceeds a predetermined angle and the switching frequency of the power switch exceeds a predetermined frequency. The time span from the first moment to the end of the first line cycle is substantially as long as the time span from the beginning of the second line cycle to the second moment.

A single phase power supply module for electric arc welders and plasma arc cutters comprising: a single phase input stage; positive and negative output terminals; a full wave rectifier connected to the input stage for rectifying the single phase voltage at the input stage; a buck converter type power factor correcting circuit for controlling current flow from the input stage to the rectifier, which buck converter has an output capacitor regulated to an intermediate voltage in the range of 100-150 volts; and, a high speed DC to DC converter having an internal transformer coupling applying voltage across the output terminals and means for regulating the applied voltage to an output voltage in the range of 0-113 volts. The module is universal and several can be connected in parallel, in series or to switch networks to construct several welders or cutters.

A switching control circuit having detection terminal, input terminal, ramp generator, program terminal, error amplifier, mix circuit, and delay circuit for power factor control is provided. The detection terminal generates a detection signal in response to the inductor discharge. An input terminal is connected for detecting a switching current signal. The program terminal determines the slew rate of the ramp signal and the maximum on-time of the switching signal. An error amplifier generates an error signal for regulating the output. A mix circuit generates a mixing signal proportional to ramp signal and the switching current signal. The switching signal is turned on in response to the detection signal, and is turned off based on the error signal. The slew rate of the mixing signal is increased in response to the increase of the input voltage. The on-time of the switching signal is increased inversely proportional to the input voltage.

An AC driven LED light string assembly is provided possessing reduced harmonic distortion and improved electrical efficiency when one or more series blocks of LED lamps is employed. In one embodiment, there is provided an LED light string employing a capacitor coupled in parallel across the light string AC input, or end connector terminals. According to another embodiment, LED light strings are to be manufactured with a substantially equal number of light strings produced with all LEDs in forward bias (anode first) and reverse bias (cathode first). This allows true randomness when large numbers of single series block LED light strings are connected in an end-to-end manner. It is possible to apply this concept to single LED lamps having two chips where one chip is powered in reverse bias to the second chip; thereby providing self-canceling harmonics within the single LED lamp.

A power controller for flourescent lamp dimming is disclosed, using all digital internal and external programmable controls. A specific ASIC is described. A gate array and microcomputer share parallel functions with fast sub-functions carried out by the gate array and slower sub-functions carried out by a micro-processor. Circuits are provided for automatic shut down when a high frequency ground fault is detected; for connecting the filaments of gas discharge lamps in a series/parallel circuit; for driving the load as close to resonance as possible but in an inductive mode; and for developing a dead time between high side and low side switches which is related to transformer current, switch current, bridge voltage or bridge voltage dv/dt.

There are provided a transmission/reception switching circuit which is small in insertion loss and harmonic distortion and allows an increase in the output power of a power amplifier and an electronic component for communication on which the transmission/reception switching circuit is mounted. As an element composing a transmission/reception switching circuit in a wireless communication system, series-connected FETs or a multi-gate FET are used in place of a diode. Gate resistors connected between the individual gate terminals and a control terminal are designed to have resistance values which become progressively smaller from the gate to which a highest voltage is applied toward the gate to which a lowest voltage is applied.

In terms of achieving a reduction in the cost of an antenna switch, there is provided a technology capable of minimizing harmonic distortion generated in the antenna switch even when the antenna switch is particularly formed of field effect transistors formed over a silicon substrate. Between the source region and the drain region of each of a plurality of MISFETs coupled in series, a distortion compensating capacitance circuit is coupled which has a voltage dependency such that, in either of the cases where a positive voltage is applied to the drain region based on the potential of the source region and where a negative voltage is applied to the drain region based on the potential of the source region, the capacitance decreases to a value smaller than that in a state where the potential of the source region and the potential of the drain region are at the same level.

A low input-current-harmonic three-phase three-level boost rectifier includes an input stage for receiving a three-phase input voltage in relation to a neutral node and an output stage adapted to couple to at least one load. The rectifier further includes one or more switching converter stages, each having a plurality of serially-connected switches coupled to the neutral node, one of the serially-connected switches operating with a fixed duty cycle while the other of the serially-connected switches operating with a variable duty cycle, the fixed duty cycle being a substantially 50% duty cycle and the variable duty cycle being less than or equal to a substantially 50% duty cycle. The serially-connected switches are coupled to clamping diodes and clamping capacitors. The rectifier further includes one or more controllers adapted to vary the switching frequency and/or duty cycle of the plurality of switches based on at least one of a condition of the at least one load or the input voltage and includes one or more decoupling stages, each including one or more inductive elements adapted to inductively decouple the output stage from at least one of the one or more switching converter stages.

The invention relates to a control circuit and a control method of a flyback convertor and an alternating current-direct current power converting circuit applying the control circuit of the flyback convertor. Within each switch period, an opening signal generating circuit is used for receiving drain-source voltage of a power switch in the flyback converter; when the drain-source voltage reaches valley value, opening signal is generated to control the turn-on of the power switch; a turn-off signal generating circuit is used for generating a turn-off signal after the power switch turns on and a turn-on time interval is completed according to a feedback error signal of a received output electric signal for representing the flyback converter; and the turn-off signal controls the power switch to turn off, so as to lead input current and input voltage of the flyback converter in a same phase and keep the output electric signal of the flyback converter constant.

Power from the dc outputs of wind-generated power collection nodes is converted to ac power of suitable quality for injection into an electric power grid. Conversion is accomplished by current regulation of the dc outputs of the wind-generated power collection nodes to the input of each one of multiple inverters in a system, with each inverter outputting multiple phase currents that are out of phase with the multiple phase currents outputted from all other inverters in the system. The multiple phase currents from all of the inverters in a system are connected to the secondary windings of a phase transformation network that produces a three phase current output having a step-shaped waveform for injection into the electric power grid. Alternatively the dc input to each one of the multiple inverters may be a combination of the dc outputs of wind-generated power collection nodes and the dc outputs of solar photovoltaic power collection nodes.

System for pulse-width-modulated class D audio amplifiers. In one preferred embodiment an adder is described to generate a difference signal responsive to an input signal and a feedback signal, a pulse-width-modulator coupled to the adder to compare the difference signal to a reference signal and produce a pulse-width-modulated signal based on the comparing, a filter coupled to an output of the pulse-width-modulator, and a loop filter having a first input coupled to the output of the filter and a second input coupled to the input of the filter, the loop filter to generate a feedback signal by applying transfer functions to signals at its inputs. The loop transfer function of the amplifier is minimum aliasing error transfer function. The minimum aliasing error properties provide low distortion and taking the feedback from the output of the filter reduces high frequency output impedance.

An LED illuminator configured to further reduce total harmonic distortion is provided. The LED illuminator has: a first LED string including a first partial LED string and a second partial LED string; a second LED string including a third partial LED string and a fourth partial LED string; a first switching circuit configured to switch between a state where only the first partial LED string is connected to a rectifier and a state where the first partial LED string and the second partial LED string connected in series are connected to the rectifier as a full-wave rectified voltage waveform that is output from the rectifier increases/decreases; and a second switching circuit configured to switch between a state where only the third partial LED string is connected to the rectifier and a state where the third partial LED string and the fourth partial LED string connected in series are connected to the rectifier, and the switching timing by the first switching circuit and the switching timing by the second switching circuit are set so as to differ from each other.

This invention mainly provides a SMT-type structure of the minimized and low-power silicon-based electret condenser microphone. Primarily integrates with the electret, silicon-based, MEMS and microphone techniques to implement the minimized and low-power silicon-based electret condenser microphone. The Silicon-based bi-diaphragm of the composite diaphragm-chip was coated with the low-dielectric macromolecule material to allow the microphone acquires the sufficient electrical charges. Moreover, the impedance matching element of the microphone that MOSFET was implemented by the MEMS technology. Conclusively, this silicon-based electret condenser microphone gains several achievements as the smallest volume, a lower bias voltage, a SMT-type structure, a lower residue stress and a lower assembly cost.

Audio signals from any array of microphones are individually filtered, delayed, and scaled in order to form an acoustic beam that focuses the array on a particular region. Nonlinear robust signal estimation processing is applied to the resulting set of audio signals to generate an output signal for the array. The nonlinear robust signal estimation processing may involve dropping or otherwise reducing the magnitude of one or more of the highest and lowest data in each set of values from the resulting audio signals and then selecting the median from or generating an average of the remaining values to produce a representative, central value for the output audio signal. The nonlinear robust signal estimation processing effectively discriminates against noise originating at an unknown location outside of the focal region of the acoustic beam.

A drive system for a refrigeration compressor such as is used in a natural gas liquefaction plant, allowing the desired compressor speed and maximum turbine efficiency to be maintained throughout varying ambient temperature conditions. A gas turbine is used with an electric starter motor with drive-through capability located on a common drive shaft between the turbine and the compressor. A variable frequency drive (VFD) is connected between the electrical power grid and the electric motor for smooth startups, but also to allow excess turbine mechanical power to be converted to electrical power by the motor operating as a generator, and delivered to the grid at the grid frequency. Pulse width modulation technology may be used to reduce harmonic distortion in the VFD's output. The starter motor also functions as a helper motor when the turbine output is insufficient to drive the compressor at the rotational speed needed to meet throughput requirements.

An apparatus for increasing the quality of sound from an acoustic source comprises in one embodiment a hollow enclosure, an acoustic source, an acoustic guide, a pair of acoustic inlet openings, a pair of acoustic exit openings, and pair of acoustic paths, wherein the acoustic inlet openings separate acoustic waves from the acoustic source and direct the acoustic waves the length of the acoustic paths to the acoustic exit openings in such a manner as to increase the quality of sound, and especially bass sound, from the acoustic source.

The present invention provides a radio frequency switch and a radio frequency module having excellent distortion characteristics without causing a further insertion loss and a greater chip size. The radio frequency switch includes: input-output terminals which are for inputting and outputting a radio frequency signal; a basic switching unit provided between two of the input-output terminals; and a control terminal which receives a control voltage for controlling conduction and interruption of the basic switching unit. The basic switching unit includes field effect transistors (FETs) connected in multiple stages, each of the FETs being a meandered FET having a meandered gate electrode, and among the FETs, one of the FETs has a finger length shorter than finger lengths of rest of the FETs, the one of the FETs electrically located closest to one of the input-output terminals.