LED lights are mainly 'energy saving and environmental protectionHowever, the input current of the LED drive power is not a sine wave, so it is necessary to test the fundamental wave power factor. So how to do this test correctly? This article takes you to understand. Why does the LED industry test the basic power factor? Power factor is usually defined as the ratio of active power to apparent power. Low power factor means high reactive power. The lower the power factor, the heavier the load of the power supply uv water purifier
equipment, and the more unstable the power grid. For high-power lamps, if the power factor is low, it may cause: equipment loss, power equipment overload, grid instability, harmonic pollution and other problems. In our impression, 'power factor is determined by the phase difference between voltage and current, and its physical meaning refers to the cosine value of the phase difference between voltage and current.' As shown below. Figure 1 Current and voltage phase angle relationship Note: The relationship above θu003d90° is only applicable to 'sine circuitThe circuit is the same. Because the LED is a semiconductor diode, it needs a direct current (DC) power supply. If it is powered by a mains power supply, it must have a rectifier, usually a diode rectifier bridge. In order to obtain as smooth direct current as possible without ripple flicker, it is usually necessary to use a large electrolytic capacitor. The LED on the back can be approximated as a resistor, so the entire circuit is shown in Figure 2. The various voltage and current waveforms of the equivalent circuit of the LED lamp in Figure 2 are shown below, where VAC is the input AC voltage, and Vc2 is the charging and discharging waveform of the rectifier diode in the LED circuit, which is the input current waveform. Because its current waveform is not a sine wave. Therefore, the entire system is a nonlinear system. Generally, the waveform of electrical equipment is close to a sine wave, and there are few harmonics. In most cases, the basic current L1 ≈ the total current LRMS, the input current distortion coefficient ≈ 1, and cos 1, so cos can be equal to the power factor. However, in the non-sinusoidal power supply circuit, the power factor has no clear physical meaning, so in the LED industry, the fundamental power factor cos 1 will be concerned. Figure 3 How to test the fundamental power factor of various voltage and current waveforms? Recommended test uv water purifier equipment 1-PA5000H power analyzer Figure 4 PA5000HLED industry pays more attention to the voltage, current, power, harmonics and power factor of the power supply. How to accurately measure these parameters is the first problem to be solved. PA5000H power analyzer has a power measurement accuracy of 0.05%, a bandwidth of 5MHz and a wealth of harmonic measurement functions, which can be widely used in the research, development and testing of LED power supplies. 1. Abundant electrical parameter measurement How to improve the power factor is a problem in the LED industry. To improve the power factor and accurately measure the power of various electrical parameters, the PA5000H power analyzer can not only directly measure the basic power factor of non-sinusoidal systems (PF1) , It can also display voltage and current waveforms in real time. The rich electrical parameter display items allow users to analyze various performance indicators. Power can help users improve the power factor, aiming to provide users with powerful data support. Figure 5 Rich electrical parameter display 2. Dual PLL source frequency multiplication technology PA5000H power analyzer introduces a dual PLL hardware circuit to synchronize the sampling frequency with the signal frequency to ensure that the sampling data is exactly an integer multiple of the signal period and eliminates The spectrum leaks, and the prepared harmonic measurement results can be obtained. 2. The power measurement accuracy is as high as 0.1%, the minimum measurement current is as low as 50 A, and the measurable power consumption is as low as 0.01 W. The basic measurement accuracy of the power meter can be as high as 0.1%. Due to the dual shunt technology, the temperature of the shunt resistor can be kept stable and the temperature drift can be reduced. The power measurement accuracy of 0.1% can be guaranteed from small current to large current measurement. In addition, PA310 can perform measurement with the highest resolution of 0.01 W in the range of 5 mA, in compliance with international standards (IEC62301, Energy Star, SPECpower). Figure 9 Harmonic test 3. The standard PAM host software can monitor and analyze the measured data in real time, and can be uploaded to the PC through standard USB, RS-232, GPIB and Ethernet interfaces. Figure 10 The upper computer test analysis.
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