389 results about "Active power factor correction" patented technology

A method for reducing the harmonics contents of an input current drawn from a power line into an electrical system without sensing an input voltage, the method comprising providing an active power factor correction controller with a switch module having a main switch and a timing device, wherein the main switch has an on-time correlated with an on-duty cycle duration, and an off-time correlated with an off-duty cycle duration, and maintaining a linear relationship between the off-duty cycle duration and the input current by using the timing device; and an apparatus for active power factor correction with minimum input current distortion, comprising an active power factor correction assembly that includes a main switch and a timing device, wherein the main switch has associated therewith an on-time correlated with an on-duty cycle duration, and an off-time correlated with an off-duty cycle duration, and wherein the timing device generates the mentioned on-time and off-time, and linearization means for maintaining a linear relation between the off-duty cycle duration and the input current.

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 method for reducing the harmonics contents of an input current drawn from a power line into an electrical system without sensing an input voltage, the method comprising providing an active power factor correction controller with a switch module having a main switch and a timing device, wherein the main switch has an on-time correlated with an on-duty cycle duration, and an off-time correlated with an off-duty cycle duration, and maintaining a linear relationship between the off-duty cycle duration and the input current by using the timing device; and an apparatus for active power factor correction with minimum input current distortion, comprising an active power factor correction assembly that includes a main switch and a timing device, wherein the main switch has associated therewith an on-time correlated with an on-duty cycle duration, and an off-time correlated with an off-duty cycle duration, and wherein the timing device generates the mentioned on-time and off-time, and linearization means for maintaining a linear relation between the off-duty cycle duration and the input current.

A circuit and corresponding method for controlling inrush current in an AC-DC power converter by providing a relay and a control circuit for limiting inrush current efficiently during cold startup, warm startup, and power line disturbance conditions. The relay is preferably connected in series with a bulk capacitor of the converter and in parallel with a limiting resistor and switch for shunting the resistor and switch so as to improve efficiency during operating conditions, at reduced size and cost. A preferred embodiment includes use of the circuit for AC-DC converters having active power factor correction.

A new class of Three-Phase Isolated Rectifiers with Power Factor Correction provides a high efficiency, small size and low cost due to direct conversion from three-phase input voltage to output DC voltage.

A light emitting diode (LED) lighting system includes a power factor correction (PFC) controller that determines at least one power factor correction control parameter from phase delays of a phase modulated signal. In at least one embodiment, a peak voltage of the phase modulated signal is a PFC control parameter used by the PFC controller to control power factor correction and generation of a link voltage by a PFC LED driver circuit. The phase delays are related to a peak voltage of the phase modulated signal. Thus, in at least one embodiment, detecting the phase delay in one or more cycles of the phase modulated signal allows the PFC controller to determine the peak voltage of the phase modulated signal.

This invention provides an electronic ballast for a fluorescent lamp, including a rectifier for converting an alternating current input voltage into a direct current output voltage, and a circuit including a combined power factor correction (PFC) stage and an inverter, wherein the PFC stage and the inverter share a switch. Also provided is a controller for an electronic ballast, including a duty ratio controller that controls a duty ratio of a switch of the ballast, and means for adjusting the duty ratio according to a nonlinear function, so that an arc is sustained across the lamp. The controller and the ballast allow dimming of the fluorescent lamp while maintaining a high power factor.

The present invention provides a method of controlling an interleaved power factor correction (PFC) circuit operating in a discontinuous conduction mode (DCM). The controller employs a normal mode of operation in which inductor currents in each PFC sub-circuit are estimated based on the monitored input voltage and monitored output voltage, and switching devices associated with each PFC sub-circuit are controlled to ensure DCM operation. As the input voltage increases, the OFF times of each PFC sub-circuit increase such that the inductor currents no longer overlap. In response, the controller activates a time-limiting mode (TLM) in which OFF time durations for each sub-circuit are based on the monitored sum of load currents as opposed to the monitored input voltage and monitored output voltage.

The invention provides a novel three-phase PFC (power factor correction) rectifier. The novel three-phase PFC rectifier is characterized in that three-phase input currents are respectively rectified by a full-wave rectifier circuit in a full-bridge mode after input voltages of three-phase alternating-current input ends are transmitted through respective boost inductors, switch circuits are respectively arranged between the boost inductors and middle points M of output voltages of output ends in a connected manner, voltages of output capacitors C1 and C2 of the output ends are boosted and stabilized by the switch circuits by means of PWM (Pulse width modulation) required by corresponding phases, and accordingly constant voltages V<o> can be outputted even under the condition of variation of loads R of the output ends in design ranges; magnet excitation and demagnetization circuits which comprise capacitors are formed between the middle points M of the output voltages of the output ends and nodes of the input voltages of the three-phase alternating-current input ends, so that the boost inductors can be decoupled under working conditions and can work in critical current modes. The novel three-phase PFC rectifier has the advantages that the novel three-phase PFC rectifier can work in the critical current modes (CRM) and also can work in CCM (continuous current mode) or DCM (discontinuous current mode) states according to requirements, and accordingly requirements on high power density and high efficiency can be met.

The invention discloses a commercial LED illumination driver. The driver comprises a rectifier module, an active quasi-resonant power factor correction module and a direct current voltage output module; wherein the input terminal of the rectifier module is connected with commercial power system, so as to rectify and filter input current; the input terminal of the active quasi-resonant power factor correction module is connected with the output terminal of the rectifier module, so as to inhibit harmonic wave produced by the LED driver and compensate the power factor; and the terminal of the direct current voltage output module is connected with the output terminal of the active quasi-resonant power factor correction module, so as to provide working voltage for LED string light. The invention applies an active power factor correction circuit working in quasi-resonant mode to LED illumination driver design and realizes substantive improvement on LED illumination driver power factor. The power factor of the LED illumination driver is improved from 0.5-0.57 to more than 0.99, harmonic wave quality index of the power system is contained in detailed design of the LED illumination design, and waveform coefficient of the LED illumination driver is improved from about 2 to below 1.2.

A control circuit coupled to a power line controlled by a dimmer having a switching device includes, for example, an active power factor correction circuit receiving power from a bridge rectifier and storage capacitor and drawing an average continuous current when the switching device is “on.” An LED power driving circuit receives a controlled current from the active power factor correction circuit and generates an output current received by at least one LED outputting visible light. A positive voltage feedback circuit senses a feedback voltage across the LED, through the LED power driving circuit, and sends the feedback voltage to the active power factor correction circuit. A pump back power circuit is electrically coupled to the LED power driving circuit and applies a bias voltage to an output of the bridge rectifier to power the active power factor correction circuit when the switching device is “off.”

The invention belongs to the technical field of light source illuminating and electronics, in particular relates to an intelligent general light-emitting diode (LED) street lamp illuminating power supply system. The system comprises an input surge protection and electromagnetic interference suppressing circuit, a BOOST-BUCK isolation backlash power factor correction switch power circuit, an LED chip temperature detection circuit, an ambient brightness detection circuit, a permanent calendar chip, a peripheral circuit, an LED failure detection circuit, a singlechip circuit and a constant-current output control circuit. In the switch power circuit of the invention, a circuit structure is simplified and circuit efficiency is improved based on an active power factor correction (PFC) control chip L6562,; and the singlechip circuit monitors the ambient brightness, the temperature of the LED chip, time and LED fault in real time by taking a chip STC12C5606AD as a control core and intelligently adjusts the output brightness of the LED according to different situations, so that energy is saved and the service life of an LED street lamp is prolonged effectively at the same time.

The invention discloses a partial active power factor correcting circuit, comprising a current detecting circuit, for real-time detecting the output current of a rectifying circuit; a power factor control unit, for obtaining the actual current waveform which reflects the real-time change of the current before the correction according to the current realtime value detected by the current detecting unit before the power factor correcting circuit starts working, and working out the continuous sine waveform as the expected current waveform with the same waveform, the same frequency and the continuous sine waveform according to the waveform; after obtaining the current waveform, the power factor control unit computes the difference between the expected current waveform and the real-time detected current actual measurement waveform, and controls the on / off of the controlled switch always in the ascending stage of the waveform and the moment with the largest difference, and controls the on / off of the controlled switch after delaying some time. The partial active power factor correcting circuit of the invention causes the actual current waveform consistent with the expected current waveform, which realizes the optimum correcting effect.

A switching power supply AC-DC-DC or AC-DC-AC with power factor corrector function is provided. The switching power supply circuit includes a quasi active shaping function that shapes an input current of a power line. In the whole system, the active switch or switches are only used to control the output power and no more current stress on the active switch or switches. It is possible to minimize the whole system size.

The invention provides a PFC (power factor correction) circuit based on a delta-sigma modulation technique and a duty ratio control method thereof. The PFC circuit comprises an input voltage ADC (analog to digital converter), a duty ratio generation circuit, an output voltage processing circuit and a digital pulse width modulation circuit in electrical connection, wherein the duty ratio generation circuit comprises a switching frequency control circuit, a Ton counting circuit and a delta-sigma modulation circuit in electrical connection; and the output voltage processing circuit comprises an output voltage ADC, a digital PI (proportional integral) compensator and a rapid dynamic response circuit in electrical connection. The delta-sigma modulation technique is utilized in the PFC circuit to realize the duty ratio control method. According to the invention, the response speed of the input voltage change can be improved, the iL waveform of the input inductive current is adjusted, the frequency spectrum of the pulse width signal is shaped, the power factor is improved and the output voltage is stabilized.

An electronic control system especially for non-linear loads, such as high pressure sodium (HPS) lamps, includes an active power factor correction circuit (APFC). The system provides a power factor correction of above 0.95; total harmonic distortion (THD) below 5%; lamp crest factor (LCF) close to unity; efficient power consumption and reliable open circuit voltage (OCV) under all power line conditions. A ballast would include integrated circuits (ICs) and a four-arm transistor bridge which is directly driven by integrated circuits. The bridge generates reversal of polarity to the load. An approximate average current feedback is derived from a load current. A resistor divider in parallel with the load provides voltage feedback. The average current feedback and voltage feedback are added together to provide an approximation of power consumed by the load, without the complex circuitry required for a true power feedback of current multiplied by voltage. That composite feedback signal is transmitted to the integrated circuit (IC) which compares it with an internal reference voltage and which adjusts the IC output to minimize the error.

A new type of the passive non-dissipative snubber with a single saturable reactor improves the performance of the boost converter used as a front-end active Power Factor Correction (PFC) in two critical areas: excess voltage stresses caused by high voltage spikes on input high voltage switching transistor of the boost converter is eliminated and EMI noise is much reduced. The high voltage spike energy instead of being dissipated as in a dissipative snubber circuits is recovered resulting in increased conversion efficiency. High voltage spike elimination also allows use of lower voltage rated devices with lower ON resistance, hence further increasing the efficiency of the PFC boost converter.

The invention discloses a self-protective variable frequency modulation ICP (Inductively Coupled Plasma) ballast which is characterized in that electric supply input is connected with an EMI (Electro-Magnetic Interference) and surge protection circuit, the input end of a filtering and rectifying circuit is connected with the EMI and surge protection circuit and the output end of filtering and rectifying circuit is connected with an active power factor correction circuit; the output end of the active power factor correction circuit is connected with a half-bridge inverter circuit, the output end of half-bridge inverter circuit is connected with a power matching network, the output end of power matching network is connected with ICP lamp body and an abnormal condition detection circuit; andthe abnormal condition detection circuit is connected with a variable frequency modulation MCU (Micro Controller Unit), the output end of the MCU is connected with the half-bridge inverter circuit and the protection circuit. The ballast provided by the invention can be used for dealing with any emergency situation at anytime; and the reliability of the ballast is improved, the conversion efficiency is improved and the cost is lowered.

The invention discloses a boost power factor correction (PFC) controller. The switching-on and switching-off of a power switching tube are controlled by switching on and switching off a signal generation circuit, so that the power switching tube is controlled to operate in a constant-frequency or variable-frequency mode. Therefore, when the boost PFC controller is used, the constant operating frequency of the power switching tube can be realized without control of a clock signal, so that the design difficulty of an input electro-magnetic interference (EMI) filter is reduced; moreover, the boost PFC controller can control the variation range of the operating frequency of the power switching tube. Compared with the conventional switching frequency jittering control technology, the invention has the advantages that: the boost PFC controller is quite convenient and has simple control scheme; frequency jittering operation can be realized; meanwhile, in the process of realizing PFC, the waveform of an input voltage is not required to be detected; the number of controller pins and peripheral devices is smaller; and cost is reduced.

The invention provides a PFC (power factor correction) control method with high input power factor and a control circuit thereof. The method comprises the steps of controlling a switching tube to be switched on and switched off according to the principle of leading impulse area to be equivalent, and leading input inductive current and sinusoidal half-wave current to have the equivalent impulse area in each switching period, thereby realizing the high power factor (PF); furthermore, the higher the switching frequency, the closer to 1 the PF value is. In the control circuit, a circuit topological structure of a Boost converter and a control circuit for realizing a variable duty ratio sequence jointly constitute a PFC stage of a commonly used LED (light-emitting diode) driving power supply, the front stage of the PFC stage is connected with the output end of a non-controllable rectifier bridge of a single-phase diode via an input filter capacitor, the back stage of the PFC stage is connected with a DC / DC (direct current / direct current) stage of the commonly used LED driving power supply via an output filter inductor and an output filter capacitor. By adopting the PFC control method, not only the very high input power factor can be realized, but also output voltage ripple can be reduced; furthermore, the control circuit is simple and easy to realize an analog circuit, thereby being conductive to large-scale integration.

The invention discloses a control circuit and a control device for a flyback power factor corrector. The control circuit and the control device are used for controlling a flyback converter which works in a critical continuous mode to realize unit power factor; breakover time of a flyback converter circuit which works in the critical continuous mode is controlled by the control circuit so that breakover time of a switch tube varies with input voltage and output voltage in a power frequency period; turn-off time of the switch tube is determined by a zero-passing moment of transformer secondary side current; and after energy of the transformer is totally released, and because a parasitic junction capacitor of the switch tube and an excitation inductor produce resonance, the switch tube is turned on by detecting a secondary side current zero-passing moment of an auxiliary winding. By the method, a power factor of the conventional flyback power factor corrector in the critical continuous mode can be improved, and the unit power factor of the flyback converter in the critical continuous mode can be acquired. The unit power factor flyback power factor corrector in the critical continuous mode is high in efficiency, and meanwhile, the unit power factor can be acquired in the whole range of the input voltage.

The invention relates to a high-pressure power supply device of a resonant converter, which mainly resolves problems that in the prior art, the peak value of electric current which passes through switching tubes is high, the control of the power supply is complicated, and operation under the direct current stabilized output state is not easy to realized. The high-pressure power supply device employs a parallel resonant topology structured circuit, and a resonant capacitor is in primary and parallel connection with a transformer. The circuit structure can be used in full bridge or half-bridge type, can be connected with an input end of an active power factor correct circuit, and also can directly employ commercial power 220V to supply power. The high-pressure power supply device can meet the mode that high-pressure power supply is applied to the direct current stabilized output state and a capacitance constant-current charge state, and can be suitable for the occasion of power supply load changing suddenly, and by combining the advantages of a resonant converter and a pulse-frequency modulating (PFM) transformer, the performance of the whole device can achieve extremely high power density.

In accordance with an embodiment, an electronic device includes a controller configured to be coupled to a first switch of a power factor corrector. The controller is configured to produce a variable switching frequency depending on a load current. For a first load current, the controller is configured to produce a first switching frequency, and for a second load current, the controller is configured to produce a second switching frequency.

A new type of the passive non-dissipative snubber with a single saturable reactor improves the performance of the boost converter used as a front-end active Power Factor Correction (PFC) in two critical areas: excess voltage stresses caused by high voltage spikes on input high voltage switching transistor of the boost converter is eliminated and EMI noise is much reduced. The high voltage spike energy instead of being dissipated as in a dissipative snubber circuits is recovered resulting in increased conversion efficiency. High voltage spike elimination also allows use of lower voltage rated devices with lower ON resistance, hence further increasing the efficiency of the PFC boost converter.

An interleaved bridgeless power factor correction (PFC) converter-based motor drive system is provided. The system includes a first inductor coupled to a second inductor. The coupled first and second inductors are coupled to a first input configured to be coupled to a first line of an alternating current (AC) power supply. The system also includes a third inductor coupled to a fourth inductor. The coupled third and fourth inductors are coupled to a second input configured to be coupled to a second line of the AC power supply. The system further includes a digital active power factor correction (PFC) controller configured to cause current in at least one of the coupled first and second inductors and the coupled third and fourth inductors to be interleaved.

The invention discloses a part active power factor correction circuit controlled by an input voltage threshold value. The part active power factor correction circuit comprises a boost circuit controlled by two loops, a voltage error amplifier, a multiplier, a current error amplifier, an input voltage sampling signal threshold value judging module, a PWM waveform generating module and an IC driven by PWM. On the basis of the boost circuit controlled by two loops, an input voltage sampling signal of the boost circuit is judged through the input voltage sampling signal sampling threshold value judging module, the IC driven by PWM is controlled to output a proper chopping signal or stop the copping signal, the boost circuit is subjected to chopping or chopping is stopped, and therefore part active power factor correction can be achieved, the number of electronic devices of the whole circuit under a high power factor value and low total current harmonic distortion is reduced, the area of the circuit can be reduced, and expenditure of the whole circuit is reduced.

A circuit and corresponding method for controlling inrush current in an AC-DC power converter by providing a relay and a control circuit for limiting inrush current efficiently during cold startup, warm startup, and power line disturbance conditions. The relay is preferably connected in series with a bulk capacitor of the converter and in parallel with a limiting resistor and switch for shunting the resistor and switch so as to improve efficiency during operating conditions, at reduced size and cost. A preferred embodiment includes use of the circuit for AC-DC converters having active power factor correction.

The invention relates to a controlling technology for an electric light source, which is a digital and intelligent power source of an electromagnetic induction light which specially provides power source for the electromagnetic induction light. The controlling technology comprises an electromagnetic compatible circuit, a waves filtering rectifier circuit, a correction circuit with source power parameters and an output circuit with a half-bridge drive power which are electrically connected in sequence. Particularly, a digital controlling singlechip is respectively connected with the correction circuit with source power parameters and the output circuit with a half-bridge drive power, a man-machine interface is also connected with the singlechip through an interface circuit, and a sensor group is connected with the singlechip; the power source of the invention simplifies the hardware circuit and has the advantages of flexible control, perfect protection system, lower fault rate, high efficiency of electrical power transformation and more remarkable energy saving effect.

A power factor correction (PFC) controller for controlling at least a switching unit is provided. The PFC controller has a feedback control circuit, a conductive current detecting circuit, and a switching control circuit. The feedback control circuit generates a feedback control signal for turning off the switch according to a feedback voltage signal. The conductive current detecting circuit has a clamp circuit, which generates a clamped signal restricted in a positive potential varying range according to a negative potential portion of a conductive-current detecting signal, and generates a cutoff signal for turning off the switch according to at least the clamped signal. The switching control circuit is utilized for controlling the switch according to the feedback control signal and the cutoff signal.

The invention provides an active power factor correction system. Through arrangement of double protections, a first current protection is implemented when the current at a DC side exceeds a first current threshold, and a second current protection is implemented when the current exceeds a second current threshold. During the first current protection, the current at the DC side is not too high, when the voltage at an AC power supply passes zero next time, the output of a PWM pulse signal is restored; during the second current protection, the current at the DC side is high already, the output of the PWM pulse signal is stopped and then the PWM pulse signal is output again until a circuit is restored to be in a normal state, the PWM pulse signal output again is a newly adjusted PWM pulse signal, so that the circuit normally runs, and overcurrent is reduced. Current protection using software is more effective than protection using hardware. In this way, the possibility of PFC restarting can be reduced, and the circuit can run more stably and can be protected from being damaged due to overcurrent.