Single-phase variable frequency power supply knowledge
July 09, 2023
The variable frequency power supply is a device that uses variable frequency technology and microelectronic technology to control the electric drive of the AC motor by changing the frequency and amplitude of the working power of the motor. It is widely used in the power system. It includes single-phase variable frequency power supply, three-phase variable frequency power supply and so on. The variable frequency power supply is a kind of electronic device device. It not only has strict restrictions on the installation environment, but also may affect the surrounding equipment during the use of the variable frequency power supply and the single-phase variable frequency power supply. Therefore, these possible effects are affected. It is meaningful to sort out and develop solutions.
The main circuit of the single-phase variable frequency power supply adopts the alternating current and voltage type frequency conversion circuit, which is mainly composed of rectification, filtering and inverter. The rectification part adopts single-phase bridge rectifier module to realize AC/DC conversion; the filter part uses filter capacitor to stabilize DC voltage; the inverter part adopts intelligent power module DIP-IPM to realize DC/AC conversion. The control loop of the variable frequency power supply is used to adjust the frequency and amplitude of the output signal of the power supply system to realize variable voltage frequency conversion. In order to ensure the safety and reliability of the system, an overvoltage and undervoltage detection protection circuit, an optocoupler isolation drive circuit, and an auxiliary power conversion circuit are provided.
To solve this problem of single-phase variable frequency power supply and three-phase variable frequency power supply, the following measures can be taken:
First, a dedicated transformer is used to supply power to the variable frequency power supply, so that the variable frequency power supply and the single-phase variable frequency power supply are separated from other power supply systems.
Secondly, a filter reactor or a plurality of rectifier bridge circuits are installed on the input side of the single-phase variable frequency power supply and the three-phase variable frequency power supply to reduce high-order harmonic components and reduce the influence of high-order harmonics of the variable-frequency power supply on other electrical facilities. .
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At present, almost all variable frequency power supplies adopt PWM control mode. This pulse modulation mode enables high-order harmonic currents on the side of the power supply during single-phase variable frequency power supply and three-phase variable frequency power supply, and causes voltage waveform distortion. This voltage waveform Changes will have a major impact on the power supply system of other devices.
In the military special induction motor pump variable frequency power supply under different debugging test SVPWM technical personnel DC input voltage load, the test data is shown in the table. Pump data notes that current harmonics really don't tremble with the effects of DC side voltage, learn to test. Only affect input power, technology. This shows that the power input SVPWM power quality is high, China a variable frequency power supply. Make sure the captain hours are really effective. Maintenance of the inverter switching power supply. 80 years in the high temperature and high temperature -40 ° C °C environment frequent start, shutdown and voltage enlightenment, the effect of closure, no pregnancy production car can not start, system collapse, the de facto principle, the power of frequency conversion is special. Further research on the determinism of the dragon digital three-phase PWM variable frequency power supply.
The same main circuit analyzes the advantages of different algorithms to achieve the PWM algorithm, which can govern the speed of the induction motor and start up for a long time, and things really demand conditions. The use of soft-opening switches will further advance the technology in the future with the conversion of power energy efficiency fraud.
