52 results about "Valley-fill circuit" patented technology

An electronic ballast for driving a gas discharge lamp includes a rectifier to convert an AC mains input voltage to a rectified voltage, a valley-fill circuit for producing a DC bus voltage, an inverter for converting the DC bus voltage to a high-frequency AC voltage for driving the lamp, a control circuit for controlling the inverter, and a flyback cat-ear power supply for supplying current to the inverter when the rectified voltage is less than a predetermined level. The flyback cat-ear power supply also provides power to the control circuit. Preferably, the flyback cat-ear power supply draws current only when the inverter is not drawing current directly from the AC mains, so as to make the input current to the ballast substantially sinusoidal. The result is a ballast having substantially improved power factor and THD. Also, the ballast operates more efficiently because the flyback cat-ear ear power supply supplies excess energy not needed by the ballast control circuitry to the inverter to be used to drive the lamp.

An electronic ballast for driving a gas discharge lamp includes a rectifier to convert an AC mains input voltage to a rectified voltage, a valley-fill circuit for producing a DC bus voltage, an inverter for converting the DC bus voltage to a high-frequency AC voltage for driving the lamp, a control circuit for controlling the inverter, and a flyback cat-ear power supply for supplying current to the inverter when the rectified voltage is less than a predetermined level. The flyback cat-ear power supply also provides power to the control circuit. Preferably, the flyback cat-ear power supply draws current only when the inverter is not drawing current directly from the AC mains, so as to make the input current to the ballast substantially sinusoidal. The result is a ballast having substantially improved power factor and THD. Also, the ballast operates more efficiently because the flyback cat-ear ear power supply supplies excess energy not needed by the ballast control circuitry to the inverter to be used to drive the lamp.

The invention discloses an active-control valley fill circuit and a control method thereof which are mainly applied to pre-stage power factor correction and energy accumulation of a switching power supply. The active-control valley fill circuit comprises an alternating-current power supply, a current rectifier, a load, an energy storing capacitor, a switch circuit and control circuit, the alternating-current power supply is connected with an input end of the current rectifier, an output end of the current rectifier is connected with the load, the switch circuit comprises two power ends and a control end of a power channel, the energy storing capacitor is serially connected with the two power ends of the switch circuit and is then parallelly connected with an output end of the current rectifier, and the control end of the switch circuit is connected with the control circuit. According to the control method, by means of presetting threshold voltage, switching between power supplying of the load and energy storing of the energy storing capacitor is realized according to changes of relationships among alternating-current phase position voltage, voltage at two ends of the energy storing capacitor and the threshold voltage. The active-control valley fill circuit has the advantages that a circuit structure is simple, a power factor is improved, output voltage is not higher than alternating-current crest voltage, and the minimum value of the output voltage can be set.

Provided herein is a power factor correction (PFC) power supply, comprising: a bridge rectifier having an input and an output, a filter capacitor connected to the output of the bridge rectifier, a transformer having a primary winding, a fly-back winding and a secondary winding, a forward diode, a fly-back diode, a storage capacitor circuit having a valley-fill circuit and a capacitor connected in parallel, and a switch connected between the primary winding and the output of the bridge rectifier. The PFC power supply features improved efficiency and low switching loss.

The invention discloses a flyback switching power circuit. A valley filling circuit is adopted in a filter circuit of the flyback switching power circuit. The work voltage of a capacitor C1 and the work voltage of a capacitor C2 in the valley filling circuit are reduced by a half, -40 DEG C electrolytic capacitor can be adopted, and a third capacitor C3 is in parallel connection to a charging diode D3 in an existing valley filling circuit, so that the withstand voltage of the third capacitor C3 is half of a peak value of input pulse direct current, and high-frequency ripple current of a back switching power 300 can be fully and effectively absorbed. A varistor RV1 and a varistor RV2 are arranged before and behind a rectifier bridge 101, and a thermistor NTC, a safety capacitor X1 and an inductor L form a multi-level two-way filter and protection circuit. The flyback switching power circuit has the advantages that the power factor is high and not affected by a value of the C3, the topological structure of the circuit is simple, the absorption effect on surging voltages is good, cost is low, the size is small, and the difference mode conduction interference degree of the flyback switching power circuit reaches the CLASS B in GB9254.

An electronic ballast for driving a gas discharge lamp includes an EMI filter, a bridge rectifier coupled to a DC bus without a conventional electrolytic capacitor, a passive valley fill circuit built as a network having 4 charge / discharge energy storage capacitors and 9 diodes (4C9C), and a resonant DC to AC high frequency inverter for powering gas discharge lamp. The 4C9D circuit divides the rectified peak voltage by four and the low output voltage of the circuit is used to provide continuous lamp operation. The result is a ballast having substantially improved power factor, total harmonic distortion, and current crest factor. The electronic ballast is provided with a dimming capability from a TRIAC based wall dimmer.

A valley-fill circuit with active conduction angle control allows use of a single storage capacitor instead of two. The capacitor is charged to the maximum voltage of the AC cycle, which makes possible use of low-capacitance high-voltage low ESR capacitors, increases energy storage density and decreases circuit footprint. This makes it feasible to use ceramic capacitors, such as a multilayer ceramic (MLCC), polyethylene, polypropylene, or any suitable capacitor type in addition to electrolytic capacitors. This improves the operational longevity and reduces the footprint of the circuitry.

The invention discloses a driving power source for a smart LED bulb. The driving power source comprises an EMI filtering circuit, a rectifying circuit, a power factor correcting circuit, a power converting circuit, a DC-DC converting circuit and a dimming control circuit, wherein the power factor correcting circuit comprises a valley filling circuit and an electrolytic capacitor connected to the valley filling circuit, and the output end of the valley filling circuit is connected with the input end of the power converting circuit; the power converting circuit is a primary side feedback power converting circuit, and the output end of the power converting circuit is connected with the dimming control circuit; the dimming control circuit comprises a single-chip microcomputer control module and an MOS transistor, the input end of the DC-DC converting circuit is connected with the output end of the power converting circuit, the output end of the DC-DC converting circuit is connected with the single-chip microcomputer control module, and the switch-on duty ratio of the MOS transistor is controlled through the single-chip microcomputer control module so that dimming and color modulation on loads can be achieved. The driving power source for the smart LED bulb is low in cost, small in size and low in power consumption; the driving power source meets the requirement for a high power factor and the requirement for non-flickering lighting of the bulb at the same time.

The present invention discloses a power supply circuit for driving an LED lamp and a power supply method. The power supply circuit is constituted by an AC-DC converter by adopting DCM-DCM. Also, the power supply circuit adopts a valley fill circuit to reduce rippling of output current and adopts the DCM-DCM to stabilize a link voltage, thereby realizing a power factor correction circuit having two-stage structures. Thus, an input voltage of the flyback converter may be improved, and a high reverse voltage may be applied.

The invention discloses an LED drive device with a valley fill circuit. The device includes a bridge rectification module connected to commercial power, a valley fill circuit, a filter capacitor C3, a constant current module connected to the bridge rectification module, and an LED load connected to both the bridge rectification module and the constant current module. One end of the filter capacitor C3 is connected to the output end of the bridge rectification module, and the other end of the capacitor C3 is connected to the ground. The valley fill circuit is connected to the output end of the bridge rectification module. The valley fill circuit is additionally adopted to greatly increase a conduction angle of a rectifier diode, input currents are made to change from spike pulses into waveforms similar to sine waves through valley point filling, the total harmonic distortion is substantially reduced, and a power factor can be increased to be around 0.9. The LED drive device has the advantages of simple structure and low cost.

The invention relates to a high-efficiency passive power factor correction circuit, which comprises a rectifier bridge circuit, an output circuit and a mutual induction valley fill circuit; and the mutual induction valley fill circuit is connected in parallel between bridge arms of the rectifier circuit and the output circuit. The rectifier bridge circuit is composed of a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4; the mutual induction valley fill circuit is composed of a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a first capacitor C1, a second capacitor C2 and a transformer T1; and the output circuit comprises a third capacitor C3.

A circuit arrangement for operating at least one light source. Cost-effective power factor correction of the system input is achieved by a combination of a charge pump and a valley-fill circuit. According to the invention, the voltage (UN2) produced by the charge pump is fed into the valley-fill circuit with a lag, for example via an inductor (L2).