Learn how to solve the difficulties of fundamental wave power factor testing in the LED industry
LED lights are mainly "energy-saving and environmentally friendly", so LED lights will be tested for power factor before they leave the factory. However, the input current of the LED drive power supply is non-sine wave, so it is necessary to test the fundamental power factor, then how to carry out this test correctly? This article will take you to find out.
Why does the LED industry need to test the fundamental power factor?
The general definition of power factor is the ratio of active power to apparent power. The low power factor indicates that the circuit has high reactive power. The lower the power factor, the heavier the load of the power supply equipment, and the more unstable the power grid. For high-power lamps, if the power factor is low, it may cause problems such as large equipment loss, power equipment overload, grid instability, and harmonic pollution.
In everyone's 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 angle difference between voltage and current."
The above relationship only applies to "sine wave circuit", Vc2. If in a non-sine wave circuit, the power factor is related to the total harmonic distortion and the fundamental wave power factor, such as in the LED light circuit.
Because LED is a semiconductor diode, it needs DC power supply. If it is powered by city power, there must be a rectifier, usually a diode rectifier bridge. In order to get the smoothest possible DC and avoid ripple flicker, it is usually necessary to add a large electrolytic capacitor. The latter LED can be approximated as a resistor, so the entire circuit is shown in Figure 2.
The LED 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. The PA5000H power analyzer has a power measurement accuracy of 0.05%, a bandwidth of 5MHz, and richness. The harmonic measurement function can be widely used in the development and testing of LED power supplies.
1. Abundant electrical parameter measurement
How to improve the power factor has always been a problem in the LED industry. To improve the power factor, various electrical parameters of the power supply must be accurately measured at the same time. The PA5000H power analyzer can not only directly measure the fundamental power factor (PF1) for non-sinusoidal systems, but also Real-time display of voltage and current waveforms, rich electrical parameter display items allow users to analyze various performance indicators of the power supply, can help users improve the power factor design and provide strong data support.
2. Double PLL source frequency multiplication technology
PA5000H power analyzer introduces dual PLL hardware circuits to synchronize the sampling frequency and signal frequency, ensuring that the sampling data is exactly an integer multiple of the signal period, eliminating spectrum leakage, and obtaining prepared harmonic measurement results.
3. 500th harmonic measurement
The PA5000H power analyzer has a bandwidth of up to 5MHz, a sampling rate of up to 2MS/s, and can measure up to 500 harmonics, and has a variety of combined display methods that can simultaneously display the content of each harmonic. In order to facilitate users to perform more detailed analysis, we A function to view the value of any harmonic is also designed. Through this function, the user can view the value of each harmonic.
1. Direct measurement of fundamental power factor
The PA300 series power meter adopts pure hardware analog filter and phase-locked loop technology. The harmonic measurement function is fully in line with the international standard for harmonic measurement IEC61000-4-7:2002. According to the fundamental frequency, voltage and current can be measured up to 50%. The sub-harmonics, whether it is the total harmonic distortion (THD), or the fundamental wave component, fundamental wave power factor, harmonic content of each order, phase difference, content rate, etc. can be directly measured.
2. The power measurement accuracy is as high as 0.1%, the minimum measurement current is as low as 50?A, and it can measure power consumption as low as 0.01W
The basic measurement accuracy of the power meter can be as high as 0.1%. Due to the application of the dual shunt technology, the steady-state temperature change of the shunt resistor can be maintained, the temperature drift can be reduced, and the measurement can be guaranteed from small current to large current. % Power measurement accuracy. Moreover, in the 5mA range, PA310 can perform measurement at a resolution of up to 0.01W, which is in line with international standards (IEC62301, Energy Star, SPECpower).
3. The standard PAM host computer software can monitor and analyze the measurement data in real time, and it can be uploaded to the PC through the standard rich communication interface USB, RS-232, GPIB and Ethernet interface.