The main circuit and control circuit of the three-phase frequency converter are designed based on three independent single-phase power sources. The main circuit employs an AC-DC-AC structure, including a rectifier, DC filter, inverter, AC filter, and transformer. The AC-DC converter is a bridge rectifier, which is slowly started by an AC contactor and achieves stable current through electrolytic capacitor filtering.
Three single-phase inverter circuits have outputs that are electrically 120 degrees apart. They are electrically independent on the primary side of the transformer and are connected to the secondary side in a star configuration to provide the required three-phase AC power. For single-phase output, voltage and waveform control are achieved using three independent single-phase controls. Consequently, each phase of the three-phase variable-frequency power supply can be used independently as a single-phase power supply, accommodating unbalanced loads and significantly enhancing the performance and adaptability of the power supply. Avionics Power Supply
The three-phase sine wave frequency converter is primarily composed of two parts:
Power circuit and control circuit.
The power circuit is primarily composed of three main parts: AC/DC conversion, DC/AC conversion, and output filtering circuit.
AC/DC Conversion: The AC input is rectified by a bridge rectifier and filtered by capacitors to achieve the appropriate intermediate circuit voltage.
DC/AC Conversion: A three-phase full-bridge circuit decomposes DC voltage into a rectangular wave with regular sine pulses. 400Hz Power Supply
Function and Principle of Sine Wave Variable Frequency Three-Phase Variable Frequency Power Supply System
A variable frequency inverter, used for converting AC to DC and back to AC, is different from a variable frequency drive used for motor speed control. The primary function of a variable frequency power supply is to convert existing AC power into a stable, pure DC power of the required frequency. An ideal AC power source has a stable frequency, voltage, zero internal resistance, and a pure sine wave (free of distortion). Since variable frequency drives are very close to ideal AC power sources, the use of inverters in industrial countries/regions can provide a better power supply environment for electrical equipment, objectively evaluating their technical performance. They are increasingly being used as standard power sources. Variable frequency power supplies mainly come in two types: linear amplifier type and PWM switch type. 400HZ Variable Frequency Power Supply
The HY series programmable variable frequency power supplies are developed using MPWM technology, with IGBT modules at the core and microprocessors as the central processing unit. They incorporate digital frequency division, analog-to-digital conversion, instantaneous value feedback, and sine pulse width modulation techniques. With isolated transformer output, they can produce a single capacity of up to 100 kVA, thereby enhancing the stability of general machines, strong load adaptability, high-quality output waveforms, ease of operation, compact size, and lightweight. They feature short-circuit, overcurrent, overload, and overheat protection functions to ensure reliable operation of the power supply.
