52results about How to "Realize constant current control" patented technology

The invention discloses an LED driver and an LED lighting device. A rectifier bridge and a rectifier and filter circuit are connected to the output port of an electronic ballast to output direct current to drive an LED load. The input end of the rectifier and filter circuit is short-circuited periodically by a power switch; the average current flowing into the LED load can be controlled and constant current control can be realized. As a result, the LED load can be driven based on the output of the electronic ballast without an inductance element; as a result, the circuit structure is simple, the cost is low and the volume is small. Meanwhile, the control difficulty is relatively low.

The invention provides an LED drive circuit and its control circuit suitable for silicon controlled rectifier dimmers. The control circuit includes: a dimming phase detection circuit; a phase filter circuit connected with the dimming phase detection circuit; A connected nonlinear reference circuit; a zero-crossing detection circuit coupled directly or indirectly to the output of the LED drive circuit; an output current analog circuit connected to the zero-crossing detection circuit; an average circuit connected to the nonlinear reference circuit and the output current analog circuit A current loop adjustment circuit; a reset circuit connected with the average current loop adjustment circuit; an intermittent delay circuit connected with the phase filter circuit; a main drive circuit connected with the reset circuit, the intermittent delay circuit and the zero-crossing detection circuit. The invention can realize high power factor single-stage dimming, and has the characteristics of no flicker, good compatibility and the like.

The invention provides a driving control system with multiple LED (light emitting diode) loads for an automobile. The driving control system comprises a first power supply unit, a second power supply unit and a control unit, wherein the first power supply unit and the second power supply unit are both provided with a sampling unit and are used for providing load voltages to respective load based on the switching conditions of the respective controlled switch unit; and the control unit is used for outputting a balance signal for controlling a constant unit in the first power supply unit and a switch control signal for regulating and controlling the switching frequency of each controlled switch unit based on the sampling result of each sampling unit, wherein the constant unit is used for converting the direct current voltage output by the first power supply unit into a corresponding load voltage and regulating the corresponding load voltage based on the balance signal, so that the power supplied for each load is kept constant, and the sampling units are used for collecting the voltage signal of each controlled switch unit and the power supply signal of each load. According to the system, the voltage of each load can be kept stable.

The invention provides a pilot arc chopped wave control circuit and a cutting machine. The pilot arc chopped wave control circuit comprises a power switch device drive circuit for generating a pulse width modulation drive signal under low power grid input condition and limiting the current of a power switch tube, a differential amplification sampling circuit for sampling and amplifying the current under low power grid input condition, a current feedback loop control circuit for regulating the pulse width of the pulse width modulation drive signal according to the amplified current signal, and a pilot arc current reflowing circuit for reflowing the current to a main loop for transmission to a spraying nozzle of the cutting machine when the power switch tube is closed and the output negative terminal is positive, wherein the power switch device drive circuit, the differential amplification sampling circuit, the current feedback loop control circuit and the pilot arc current reflowing circuit are conductively connected in sequence. Ultramicrocrystal main transformer bias and pilot arc overcurrent protection are avoided, the success rate of arc starting is increased, the pilot arc current is stable, the arc cannot be broken, the small-current constant-current control is achieved, and the problems of arc starting and arc breaking under low power grid voltage input condition are solved; and meanwhile, the loss of the pilot arc and the pilot arc of the spraying nozzle is reduced, and the control circuit is long in service life, durable and reliable.