76results about How to "Improve Harmonic Distortion" patented technology

A controller for determining the duty-ratio for a pulse width modulator of a converter includes an inner current loop, an outer voltage loop and a multiplier with an input voltage feed forward to connect both loops. A prediction unit determines a correction signal i_cor that is added to the reference current i_ref by means of an adder and it further determines a sample correction signal to correct the current samples in the current loop. This error-controlled duty-ratio prediction with sample correction results in an improved total harmonic distortion as well as in an improved power factor of the converter.

Loudspeaker and other transducers of the dual-voice-coil/dual-magnetic-gap type can be improved by the addition of one or more annular shorting rings strategically located in the vicinity of the two magnetic gaps. The shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current. The location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic distortion and higher order even harmonic distortion, a centered location on the flux loop centerline, i.e. centered in the magnetic gap, favors reduction of third harmonic and higher odd order harmonic distortion, while location outside the flux loop as defined by its center line but near the voice coil acts to generally reduce harmonic distortion and reduce the voice coil inductance. Thus a plurality of rings can be strategically deployed at different locations so as to optimally suppress both even and odd order harmonic distortion and to reduce the voice coil inductance.

A loudspeaker includes a frame, a diaphragm disposed in the frame, a motor system for the diaphragm including a magnet system attached to the frame and a voice coil system attached to the diaphragm. A surround is disposed in a relatively non-supporting and non-stressing relationship to the diaphragm and the frame. A centering system is located in the frame for the cone and/or the voice coil and provides support therefore. The centering system includes at least two identical spiders arranged back-to-back in axial distance from each other.

The invention discloses a T-shaped multi-level inverter circuit based on reverse blocking IGBT (Insulated Gate Bipolar Transistor) antiparallel connection. The T-shaped multi-level inverter circuit comprises a two-way controllable switch (1), a power device (2) and a direct-current capacitor (3); the two-way controllable switch (1) comprises a plurality of reverse blocking IGBTs which are in antiparallel connection with each other in pairs; one side of a connecting wire of the reverse blocking IGBTs in antiparallel connection with each other in pairs after being connected in parallel is connected with a power switch tube, while the other side of the connecting wire is connected with the direct-current capacitor (3). The T-shaped multi-level inverter circuit is characterized in that after the reverse blocking IGBTs are in antiparallel connection with each other to form the two-way controllable switch, the antiparallel reverse blocking IGBTs are connected at the midpoints of a plurality of series capacitors without increasing the conduction loss, and then a plurality of midpoint voltage clamping circuits to realize five-level outputs, and with the increase of the number of output levels, the harmonic distortion of an output voltage is improved, the desired filter inductance is lower or the switching frequency can be reduced accordingly.

In a SPDT switch, a resistor for leak path is connected between a terminal for antenna and a reference potential. The resistor for leak path allows charge capacitances accumulated in electrostatic capacitor elements provided as DC cut capacitors connected to transmission signal terminals and reception signal terminals to be discharged and allows rapid lowering of a potential at the terminal for antenna. In the SPDT switch, a switching characteristic is improved and a delay in the rising edge of a low-power slot which comes after a high-power slot is reduced.

A multi-driver transducer having symmetrical magnetic circuits and symmetrical coil circuits, wherein one or more pieces of circular or annular partitions made of a non-magnetic material are used to bond two or more sets of dual magnetic gap and dual coil driver units (01 or 02) into one integrated magnetic core. Four or more coaxial isodiametric annular magnetic gaps are formed between the inner circumferential face or outer circumferential face of one or two tubular magnetic yokes embedded in an open-end tubular thin wall of the bracket and the vertical circumferential face of an upper pole plate and a lower pole plate of the magnetic core, four or more coaxial and isodiametric coils are inserted in the four or more coaxial and isodiametric annular magnetic gaps, and the winding direction, connection manner, and necessary technical features of the coils are governed; thus, the multi-driver transducer having one or more pairs of mutually-repelling magnets, symmetrical magnetic circuits, and symmetrical coil circuits is constituted. Back electromotive force and inductance acquired via induction by the transducer during the working process are mutually offset. The transducer has resistive load features or near-resistive load features, and has super-high sensitivity, high resolution, and high-fidelity quality.

The LED lighting apparatus includes: a rectification block; an LED block including a first light emitting group and a second light emitting group; a charging/discharging block configured to charge electric charges in a charging period, and discharge electric charges in a discharging period; a driving control unit configured to determine a voltage level of a rectified voltage, controls a path selection switch to connect the rectification block to the LED block and controls the charging/discharging block to charge electric charges in the charging period, and controls the path selection switch to connect the rectification block to a ground and controls the charging/discharging block to discharge electric charges from the charging/discharging block to the LED block in the discharging period; and a path selection switch configured to connect the rectification block to the LED block in the charging period, and connect the rectification block to the ground in the discharging period.

The invention discloses a single-phase double voltage-boosting and reducing power factor correcting circuit which comprises a single-phase three-potential voltage-boosting and reducing power factor correcting circuit, a single-phase three-potential voltage-reducing power factor correcting circuit, a first output capacitor, a second output capacitor and a midline, wherein the single-phase three-potential voltage-boosting and reducing power factor correcting circuit is used for receiving an input voltage, is provided with a first output end, a middle point and a second output end and is used for outputting a first output voltage and a second output voltage; the single-phase three-potential voltage-reducing power factor correcting circuit is used for receiving the input voltage and is coupled to the first output end, the middle point and the second output end; the first output capacitor is coupled to the first output end and the middle point; the second output capacitor is coupled to themiddle point and the second output end; and the midline is coupled to the middle point. The single-phase/three-phase double voltage-boosting and reducing power factor correcting circuit and the control method thereof solve the problem of overlarge conduction loss in a voltage-reducing working mode of a voltage-boosting diode in a traditional single-phase three-potential voltage-boosting and reducing power factor correcting circuit.

The invention discloses an LED (Light Emitting Diode) constant-current driving circuit. The LED constant-current driving circuit comprises a voltage reference unit which is used for generating the reference voltage, a peak current detection keeping unit, an error amplifier unit, a current comparator unit, a demagnetization detection unit and a self-adaptive unit. According to the LED constant-current driving circuit disclosed by the invention, the LED constant-current control can be realized, the service life of an LED can be prolonged, the problem of CTR (Current Transmission Rate) attenuation of an optical coupler is overcome as the circuit is free from an optical coupler device, the stability of the circuit is increased, the EMI (Electro Magnetic Interference) and the harmonic distortion can be greatly improved as the switching frequency of a power switching tube of the circuit is a variable frequency, an external circuit can be greatly simplified by adopting the circuit, and the using cost can be greatly reduced.

A device includes a snapback clamp circuit configured to clamp a supply voltage in response to the supply voltage exceeding a trigger voltage level. In at least one embodiment, the snapback clamp circuit includes a clamp transistor and a programmable resistance portion that is responsive to a control signal to calibrate the trigger voltage level. Alternatively or in addition, the snapback clamp circuit may include a programmable bias device configured to calibrate the trigger voltage level by biasing a gate terminal of the clamp transistor. In another particular embodiment, a method of calibrating a snapback clamp circuit is disclosed. In another particular embodiment, a method of operating an integrated circuit is disclosed.

An AC light emitting device, a driving device thereof and a driving method are disclosed. The driving device includes a sub-driving part turned on corresponding to each of positive and negative voltage regions of an AC voltage source to provide current paths for operating at least two LEDs, and a free-charge part charging with a voltage to be supplied to one of the at least two LEDs which is not operated while the other LED is operated by the sub-driving part. The AC light emitting device, the driving device thereof and the driving method thereby can solve problems, such as a decrease in power factor, severe total harmonic distortion, excessive flickering, and the like, due to operating characteristics of the AC light emitting device by application of an AC voltage source thereto.

The invention mainly relates to a constant-power LED driving system and a constant-power control method. A driving system for driving an LED string group is provided in a topological structure comprising an LED string group; the constant-power LED driving system comprises a main transistor connected with the LED string group in series and a current sensing resistor; an alternating current is rectified by a bridge type rectifier to generate a pulsating voltage to supply power to the LED string group; a provided reference voltage is input at the positive phase end of a first operational amplifier; the total current waveform, which flows through the LED string group, can be close to sine wave under a constant power condition, so that it is ensured that the input power still can be maintained at a basically constant mode when the voltage provided to the LED string group is in an overhigh condition; and relatively high power factor/total harmonic distortion index is achieved.

The invention discloses a cascaded two-level inverter SVPWM modulation method based on dodecagonal space voltage vectors. First and second three-phase two-level inverters which are cascaded are comprised. The method comprises the steps that 1 a dodecagonal space voltage vector distribution map is constructed; 2 which sector in which a reference voltage vector Uref is located in twelve sectors of the dodecagonal space voltage vector distribution map is determined; 3 two non-zero voltage vector action times T1 and T2 and a zero voltage vector action time T0 in the area are calculated; 4 a spacevoltage vector switching point is calculated; and 5 switch positions corresponding to the voltage vectors are determined, and according to the principles of waveform symmetry and the minimum number oftimes of switch, the SVPWM waveform of the sector is determined. According to the invention, the output phase voltage amplitude is increased by 3.6% compared with hexagonal space voltage vector pulsewidth modulation; the direct current bus voltage utilization rate is increased by 11.5%; the phase voltage output by the inverters does not contain (6n+/-1) harmonics; and harmonic distortion is significantly improved.

An audio switch circuit includes negative feedback paths and a transistor that serves as a switching component. The negative feedback paths are turned ON to couple a source voltage and a drain voltage of the transistor to the gate of the transistor when the audio switch circuit is turned ON. The negative feedback paths reduce the slew rate of the gate-to-source voltage of the transistor, thereby slowing the turn-ON of the audio switch circuit to prevent or minimize unwanted audible noise. The negative feedback paths can be turned OFF after a period of time after the audio switch circuit is turned ON for improved total harmonic distortion.

The invention relates to a variable frequency triangular carrier generator, and an APF based on the carrier period modulation technology and containing the generator. The generator comprises the following program modules: a variable frequency triangular carrier modulation signal generation module; a variable frequency triangular carrier frequency instantaneous value waveform generation module; a variable frequency triangular carrier generation module; and a digital variable frequency triangular carrier generation module. The variable frequency triangular carrier generator provided by the invention is used for replacing the triangular carrier generator with fixed frequency, the harmonics at the carrier frequency can be eliminated by means of the rule that the triangular carrier frequency changes with a periodic triangular signal, and the total harmonic distortion is improved while the current electromagnetic interference on an APF network side is suppressed.

The invention provides a switch-mode power supply and a control circuit and control method thereof. The switch-mode power supply converts input voltage into output voltage and comprises a power level circuit and a control circuit, wherein the power level circuit is used for switching at least one power switch to convert input voltage into output voltage according to a driving signal, the control circuit is coupled with the power level circuit and comprises a pulse width modulation (PWM) circuit and a shaping and weighing circuit, the PWM circuit is used for generating a PWM signal according to a feedback signal, and the shaping and weighing circuit is coupled with the PWM circuit to receive the PWM signal and delay the time when rising edge or falling edge occurs in the PWM signal in each period for a preset period of time according to input voltage, so that the driving signal is generated.

The invention relates to a sound converter, particularly a sound converter including suspension devices used for connecting the lower end or lower end side surface of a voice coil to a frame so as tosuppress splitting and vibration. The sound converter includes a frame; a bottom plate including an outer bottom plate and an inner bottom plate; a top plate including an outer top plate and an innertop plate; a center magnet mounted between the inner top plate and the inner bottom plate; first to fourth sub-magnets mounted between the outer top plate and the outer bottom plate and spaced apart from the center magnet by a magnetic gap; a first suspension device including a center dome member and an edge dome member mounted at the top part of the frame; a second suspension device including FPCB and attached to the bottom surface of a vibrating diaphragm; a voice coil having a lower end positioned in the magnetic gap and an upper end attached to the bottom surface of the second suspension device; and a third suspension device including first to fourth dampers. The dampers penetrate space among the sub-magnets to connect the lower end of the voice coil to the frame.