With the increasing complexity and integration of electronic systems, variable frequency power supplies, AC adjustable power supplies and other electronic systems have higher and higher requirements for reliability, stability and safety, and the importance of circuit protection design is also increasing. stronger. More and more laboratories will use AC variable frequency power supply as the power supply for some precision instruments, but there are some problems in this way, because most of the current AC variable frequency power supplies, whether it is a three-phase variable frequency power supply or a single-phase variable frequency power supply, mostly use PWM The way to make, such a UV variable frequency power supply will more or less have conduction interference when the power is output, the reasons are as follows:
The electromagnetic compatibility of the variable frequency power supply mainly includes the following parts: the input and output conduction interference of the power supply; the radiation disturbance of the power supply; the anti-interference characteristics of the variable frequency power supply. Shenzhen Hengxinlong Technology variable frequency power supply series products adopt advanced PWM (pulse width modulation technology), which makes this product have the advantages of small size, light weight and high efficiency. Digital signal processing technology provides high-precision and high-speed measurement functions such as voltage, frequency, current, apparent power, and power factor. And use high-power IGBT module design to reduce circuit complexity, improve product stability, and reduce power loss. In addition, a number of ultra-isolation transformers completely isolate the mains and the load to increase the functions of the whole machine, and various superior test performances, which can ensure the accuracy of the test values.
The main interference sources that affect the detection circuit of the instrument are the strong electromagnetic field and the fluctuation of the AC adjustable power supply. The latter has a small impact on the instrument and is easier to overcome. Generally, only a good power transformer (triple shield) and the instrument The filtering and voltage stabilization circuit of the DC part is processed well (such as frequency stabilization and stabilization power supply, uninterruptible power supply, etc.) to control the power fluctuation interference to a low level, and it will hardly affect the measurement accuracy of the instrument, even if it does, It is also far below the requirement of instrument accuracy and can be ignored. The former, that is, the interference of strong electromagnetic fields, has a large interference to the instrument and is not easy to overcome. This type of interference is induced voltage in the loop of the instrument due to electromagnetic induction, which affects the normal operation of the instrument circuit or the normal operation of the program.
For this kind of interference, general instruments adopt certain anti-interference measures, mainly adding a filter circuit to the instrument loop to overcome or weaken the interference, that is, use a band-pass filter or a band-stop filter, and selectively Block or bypass interference signals. Most of these circuits are aimed at fixed interference frequencies, such as power frequency interference, which can block or filter power frequency interference and its higher harmonics, and the circuit is relatively easy to implement. The strong electromagnetic interference of frequency changes seems to be inadequate. Although some advanced smart meters have digital filtering function, which can selectively filter out interference signals of a certain frequency, they still work on a fixed interference frequency according to the set time constant, and they are still powerless to change the interference frequency. Can't be overcome well. The electromagnetic interference generated during the operation of the variable frequency power supply is exactly the strong electromagnetic interference that exceeds the power frequency range and changes. For the above problems, for most users, the running instrument cannot be replaced in large numbers, and it is necessary to adopt on-site anti-intensity outside the instrument. Interference measures.
The multi-function variable frequency power supply is a standard AC power supply device, and can simulate the standard power supply of various countries in the world. Input a single AC voltage and frequency, internally through AC to DC; after DC to AC converter rectification conversion, it will be generated by itself-a very stable and pure sine wave with high activation current, which can display multiple parameters (such as: voltage, frequency, Current, apparent power, power factor, etc.).
