As far as the current domestic LED driver power supply design trend is concerned, the product that uses the capacitor buck principle to complete the drive circuit design has gradually established itself in the market. LED power products with this design have better stability and lower cost. In today's article, we will briefly analyze and introduce the principle of capacitor buck in LED driver power.
The block diagram of the buck principle in the LED drive power circuit made by the capacitor buck principle is shown in the figure below. When a sinusoidal AC power source U (here, the most common 220VAC, 50HZ is used as an example) is applied to the capacitor circuit, the charge on the plates of the capacitor and the electric field between the plates are a function of time. That is to say: the effective value and amplitude of the voltage and current on the capacitor also follow Ohm's law. That is, the amplitude of the voltage applied to the capacitor is constant, and when the frequency is constant, a stable sinusoidal alternating current ic flows. The smaller the capacitive reactance, the larger the capacitance value, the larger the current flowing through the capacitor, and a suitable load in series with the capacitor, a reduced voltage source can be obtained, which can be rectified, filtered, and regulated. One problem to be noted here is that in this circuit system, the capacitor only consumes energy in the circuit without consuming energy, so the efficiency of the capacitor step-down circuit is high.
LED drive power capacitor step-down block diagram
Under normal circumstances, the LED power supply designed by the capacitor buck principle, its main drive circuit will be composed of buck capacitor, current limiting, rectification filtering and voltage regulation shunt. Among them, the step-down capacitor is equivalent to the step-down transformer in the ordinary voltage regulator circuit, directly connected to the AC power circuit, almost all AC power supply U, should use non-polar metal film capacitor. At the moment of closing the power supply, there may be a peak-to-peak value of the positive or negative half of U. At this time, the instantaneous current will be large. Therefore, a current limiting resistor must be connected in series in the loop to ensure the safety of the circuit. The main reason for the circuit. The design requirements of the rectifier filter circuit part are the same as those of the ordinary DC stabilized power supply circuit. The reason why the voltage shunt circuit is needed is because the voltage RMS is stable and is not affected by the change of the load current. Therefore, in the voltage regulator circuit, there must be a shunt circuit in response to the load. The magnitude of the current changes.
Zinc Rod high purity of over 99.995% was widely used in vacuum coating and other purposes.
Zinc Rod
Zinc Rod,Pure Zinc Rod,Zinc Anode Rod,Zinc Welding Rod
Shaoxing Tianlong Tin Materials Co.,Ltd. , https://www.tianlongspray.com