What does medium frequency variable frequency power supply mean?

The medium frequency variable frequency power supply is based on the microprocessor in MPWM mode and is designed with an active component IGBT module. It uses technologies such as digital frequency division, D/A conversion, instantaneous value feedback and sinusoidal pulse width modulation, and uses the technology of separating transformer output to improve the stability of the entire machine.

What does medium frequency variable frequency power supply mean?

The medium frequency variable frequency power supply is based on a microprocessor in MPWM mode. It is designed with an active component IGBT module. It uses digital frequency division, D/A conversion, instantaneous value feedback and sinusoidal pulse width modulation and other technologies to separate the transformer output. The stability of the entire machine is improved.

The variable frequency power supply converts the alternating current of the main power supply from AC→DC→AC into a pure sine wave output. Its output voltage and frequency can be adjusted within a certain range. Currently, there are two main types of variable frequency power supplies: SPWM switching type and linear amplification type.

At present, there are two main types of variable frequency power supplies in China: analog type and program control type. What they have in common is the use of sinusoidal pulse width modulation (SPWM) technology. All SPWM circuits use a full-bridge inverter circuit implemented by hardware. The difference is that the analog full frequency and voltage adjustment knobs are implemented by hardware settings, the frequency and voltage adjustments are completed in hardware, and the main circuit is completely separated from the measured display parameters. Abnormal measurement display will not affect the normal output, and the human-computer dialogue cannot reach the ideal state, and the communication with the host is inconvenient. The program control type is actually a digital-analog hybrid system. It uses 196 single-chip microcomputers as the control core. The frequency and voltage are adjusted by programming. The program can also adjust the effective value of the voltage. The single-chip microcomputer can also monitor tasks such as measurement display. It is more convenient for advanced computers to transfer data to microcomputers, but if the process layout is unreasonable or the program is not written, a crash reset phenomenon may occur. In China, in addition to these two types, there is also a type that uses linear amplification technology. The occupancy rate of this power supply is very small, only a few kilowatts.

There are also two types abroad: one is almost the same as the existing domestic simulation principle, and the other is a program control type that uses DSP as the control core. Compared with the single-chip microcomputer, DSP is faster than CPU, more integrated, and has a higher memory capacity. As a reduced instruction set computer (RISC), DSP can use PI to adjust the error between the effective value of the feedback voltage and the effective value of the given voltage. In addition, measurement and display can be completed by DSP, and most instructions are completed in one cycle. Multiple instructions can be completed using internal parallel processing technology, allowing DSP to form a precision waveform generator together with an external A/D converter to provide a reference voltage signal. Not only can you simulate grid voltage fluctuations and generate the required dynamic interference voltage to check the power supply voltage performance of the equipment in the presence of dynamic interference, but you can also emit sine waves.

You can also simulate frequencies and voltages around the world and in power grids. When the power supply voltage is distorted, the voltage distortion will produce the periodic strain voltage required to test the performance of the instrument. PWM control is a technique for modulating the pulse width. That is, by modulating a series of pulse widths, the desired waveform can be equivalently obtained. PWM waveforms can be divided into two types: constant amplitude PWM waves and unequal amplitude PWM waves. The PWM wave generated by the DC power supply is usually an equal amplitude PWM wave. If the amplitude of each pulse is equal and the width varies according to the sine law, the PWM waveform becomes an SPWM waveform.

Working principle of medium frequency output variable frequency power supply

The following is an example of the working principle of a 400HZ medium frequency variable frequency power supply. The 400HZ medium frequency power supply inputs a single AC voltage and frequency, and passes from AC to DC internally to perform DC to AC conversion and rectification, producing a very stable pure sine wave. The principle is as follows. As shown in the figure, the power supply inputs the AC grid voltage and frequency. After internal conversion from AC to DC and DC to AC, it will produce a very stable signal. It is a pure sine wave in itself.

The above picture is the working principle diagram of 400HZ medium frequency power supply.

Medium frequency output variable frequency power supply function

GBT's inverter output technology is an advanced variable frequency power supply technology currently used internationally. The high-performance precision power supply is designed with advanced microprocessor control technology. It has the display and protection functions of overvoltage, undervoltage, overcurrent, overload, short circuit and other alarm faults. It has the ability to ensure the safety of variable frequency power supply and other electrical equipment. It has a good human-machine interface, good output waveform quality, strong load adaptability, easy operation, light weight and small size. The variable frequency power supply with sinusoidal output, adjustable output frequency and voltage can provide high-quality AC power required by many electrical installations.

At present, this medium frequency output variable frequency power supply is easy to use and cost-effective, and plays an important role in fields such as practical research and development, industrial production, aviation and military.