4290 results about "Zero crossing" patented technology

An apparatus, method and system are disclosed for providing AC line power to lighting devices such as light emitting diodes (“LEDs”). An exemplary apparatus comprises: a plurality of LEDs coupled in series to form a plurality of segments of LEDs; first and second current regulators; a current sensor; and a controller to monitor a current level through a series LED current path, and to provide for first or second segments of LEDs to be in or out of the series LED current path at different current levels. A voltage regulator is also utilized to provide a voltage during a zero-crossing interval of the AC voltage. In an exemplary embodiment, first and second segments of LEDs are both in the series LED current path regulated at a lower current level compared to when only the first segment of LEDs is in the series LED current path.

An active rectifier and a wireless power reception apparatus using the same are disclosed herein. The active rectifier includes first and fourth switches, second and third switches, and a synchronization control unit. The first and fourth switches are turned on while the voltage of an alternating current (AC) input is negative, and apply the current of the AC input to a rectifying capacitor. The second and third switches are turned on while a voltage of the AC input is positive, and apply the current of the AC input to the rectifying capacitor. The synchronization control unit compensates for the delay time of the comparator for detecting zero-crossing of the AC input so as to switch the first to fourth switches.

A gateway may be configured to synchronize transmissions of a plurality of faulted circuit indicators (FCIs). The gateway may determine a time delay from a zero crossing of a power line signal and obtain network information from the at least one FCI from the plurality of FCIs. The gateway may identify a proximate FCI that is closest to a gateway based on at least one link parameter, and assign the determined time delay to the proximate FCI. The gateway may receive confirmations that at least one FCI received the determined time delay, and has synchronized transmissions based on the determined time delay and the zero crossings of the power signal.

An electrosurgical system and method are disclosed. The system includes an electrosurgical generator adapted to supply electrosurgical energy to tissue. The generator is further adapted to supply an electrosurgical signal at a variable power level. The generator includes sensor circuitry adapted to sense tissue impedance and / or an electrosurgical signal zero crossing. The generator also includes a controller, which may include a microprocessor, that is adapted to receive a tissue impedance signal and / or a waveform zero crossing signal. The controller is configured to monitor tissue impedance, and in response to a threshold value of impedance being reached, to cause a power level of the electrosurgical energy to transition from a first power level to a second power level. The slew rate of the power transition may be in accordance with a transition function, such as a cosine function. The power transition may additionally or alternatively be performed during, or correlated with, an electrosurgical signal zero crossing. The system also includes an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue for treatment.

In a method and apparatus for controlling power factor correction in mixed operation modes, a frequency of the input voltage is obtained by detecting the zero crossing points of the input voltage. A peak of the input voltage is obtained by detecting input voltage with 90 degree phase. Thus, the present invention predicts the input voltage by its frequency and peak and the characteristic of the sine wave. A digital signal processor computes the duty and frequency of a boost switch, switching the operation mode of the boost converter among continuous mode, critical mode and discontinuous mode according to input voltage or the load. According to another aspect, the operation is switched to critical mode from the average current mode when a zero current is detected before the charging and recharging cycle of the boost switch is finished. Overcurrent protection may be achieved by controlling current in response to detected voltage to provide a substantially constant power level. The overcurrent protection may be adaptive in nature.

The present invention relates to a method and device for improving concealment of frame erasure caused by frames of an encoded sound signal erased during transmission from an encoder (106) to a decoder (110), and for accelerating recovery of the decoder after non erased frames of the encoded sound signal have been received. For that purpose, concealment / recovery parameters are determined in the encoder or decoder. When determined in the encoder (106), the concealment / recovery parameters are transmitted to the decoder (110). In the decoder, erasure frame concealment and decoder recovery is conducted in response to the concealment / recovery parameters. The concealment / recovery parameters may be selected from the group consisting of: a signal classification parameter, an energy information parameter and a phase information parameter. The determination of the concealment / recovery parameters comprises classifying the successive frames of the encoded sound signal as unvoiced, unvoiced transition, voiced transition, voiced, or onset, and this classification is determined on the basis of at least a part of the following parameters: a normalized correlation parameter, a spectral tilt parameter, a signal-to-noise ratio parameter, a pitch stability parameter, a relative frame energy parameter, and a zero crossing parameter.

A control circuit for a switch unit of a clocked power supply circuit, the switch unit being designed to effect input-side excitation of a resonant transformer arrangement, comprises an input for receiving an auxiliary signal from the resonant transformer arrangement. The auxiliary signal exhibits an essentially fixed phase relation to a load alternating current flowing through a resonant circuit of the transformer arrangement. The control circuit further comprises a phase detector designed to detect reference crossing moments when the auxiliary signal crosses a predefined reference value, a driver controllable to switch the switch unit, and a synchronizer designed to synchronize a turn-on of the switch unit by the driver with regard to a phase position with the auxiliary signal so as to achieve a turn-on of the switch unit within a predetermined time interval around a zero crossing of a voltage present across the switch unit, or of a current flowing through the switch unit. The synchronizer is further designed to receive information about the reference crossing moments from the phase detector, and to provide a turn-on signal to the driver with a fixed phase delay at the reference crossing moments, so as to define turn-on moments at which the driver is to turn on the switch unit. The control circuit further comprises a detector designed to determine an amplitude information which depends on an amplitude or a mean value of the auxiliary signal, and a regulator designed to change an operating frequency in dependence on the amplitude information supplied by the detector, and to determine a period duration between turn-off moments at which the driver is to turn off the switch unit as a reciprocal of the operating frequency. An inventive resonance converter enables independent control of frequency and turn-on moments, or duty cycle, and thus enables a particularly efficient operation of the resonance converter, and a particularly precise regulation.

A low noise electronic three phase bridge controlled brushless DC motor suitable for whiteware appliance pumps and other appliance applications. Back EMF zero crossing sensing is used to determine rotor position and thus stator winding commutation times. Motor torque and speed are controlled by pulse width modulating the operation of that bridge switching device which has just been switched from an OFF state to an ON state on each new commutation. All three stator windings have current flowing in each winding commutation to improve motor current waveform and thereby reduce motor noise, but the current in one winding is always terminated before the end of the commutation period to allow the back EMF in that winding to be sensed to zero crossing.

A single-ended to differential converter uses a cross-coupled latch that maximizes the output zero-crossing symmetry and is self compensating over PVT variations. An in-phase driving signal is provided by an always-on transmission gate coupled to the input. An out-of-phase driving signal is provided by an inverter coupled to the input. The in-phase and out-of-phase driving signals each drive an input of the cross-coupled latch. The in-phase driving signal from the always-on transmission gate starts to bring the cross-coupled latch into conduction, and when the out-of-phase driving signal arrives, the simultaneous driving of the cross-coupled latch causes a rapid and symmetric transition of both outputs of the cross-coupled latch.

Apparatus for determining the frequency of an ac power signal, includes sensing circuitry to sense the ac signal. In a digital implementation of the invention, a double average of the samples is generated by a processor as the sum of the most recent sample, twice the next most recent sample plus the third most recent sample. The least mean square of a running window of the most recent double average signals is generated to avoid discontinuities at the zero crossings and to reduce the effects of noise. The frequency is determined from this least mean square value of the window of double average signals. As implemented in a protective relay, a trip signal is generated if the frequency is out of limits.

A circuit for providing power factor correction in accordance with an embodiment of the present application may include a boost converter circuit and a control circuit receiving as inputs a rectified AC input voltage from a rectifier, a signal proportional to current through the boost inductor and the DC bus voltage across the capacitor of the boost converter. The control circuit provides a pulse width modulated signal to control the on time of a PFC switch. The control circuit further includes a voltage regulator and a current regulator. The current regulator includes a difference device operable to subtract a signal proportional to the inductor current from the current reference signal, a PI controller adapted to receive the output of the difference device and provide a first control signal, a feed forward device operable to receive the rectified AC input voltage and to provide a second control signal with a smaller dynamic range than the AC input voltage, and an adder operable to add the first control signal to the second control signal to provide a PWM reference signal for generating the pulse width modulated signal. A zero crossing detector and vector rotator may be provided to provide a clean sinusoidal reference to the current regulator. A partial PFC regulator may be provide to provide partial mode PFC if desired.

The invention discloses a serial arc-fault circuit interrupter, comprising a power circuit, a current sensor, a current sensing circuit, an amplifying and filtering circuit, a voltage zero-crossing comparison circuit, a microcontroller, a trip trigger circuit. A current transformer collects current signals in a circuit; the current signals are converted into voltage signals through the current sensing circuit, and are input into the microcontroller through the amplifying and filtering circuit; the voltage zero-crossing comparison circuit inputs a voltage zero-crossing pulse signal into the microcontroller; the microcontroller judges arc emergence through arc characteristics analysis and is disconnected with a load circuit by the trip trigger circuit. The protection method transforms a one-dimensional time signal into a two-dimensional time signal by utilizing short-time Fourier transform, analyzes changes of fundamental component, even-order harmonic and odd harmonic component of eachcyclic wave, extracts and judges the serial arc-fault characteristics. The method has the advantages that multiple characteristics are extracted to realize comprehensive judgment of fault arc, missedtrip and balk generated in serial arc detection in small load are prevented, and the reliability of judgment is improved effectively.