Frequency converter and inverter repair points, China Electrical Appliance Switch Factory, www.guofadq.com 15957745520
Converter now as the main recommended products, in which the vector frequency converter and fan frequency converter is a great hope. We also carried out on a frequency converter unit, to explain the answer for some of this stuff. So it is necessary to introduce converter. In fact, inverter English translation should be: Variable-frequency drive, but the domestic general translation Inverter. The following details down converter system, because only by understanding its system structure, we can understand how to maintenance and repair frequency converter.
Inverter system generally consists of 3 parts: AC motor, controller and interface. The following components are introduced one by one on one.
Operation interface
Converter interface for an operator provided to start and stop the engine, adjust speed by means of. At the same time the operator control functions also additional includes manual and automatic speed control switch selection, to ensure that the process from the exterior control signal. In addition, the operator interface includes an alphanumeric display lamp and provide information about the operation of the drive information instrument. Keyboard interface and the display unit is provided on the inverter controller before regular in the above picture. Usually, keyboard and display, but cable connection and installation variable frequency controller from a short distance. Most also provides input and output ( I / O ) terminal connection button, switch equipment interface or control signal. Serial communication port may also allow the converter is usually to configure, regulation, monitoring and control computer.
This is a complete inverter system constitution, only in-depth understanding of its basic form, can repair operation. Such as through static test, dynamic test, diagnose the fault source, finally solve the problem.
AC motor
In general inverter system using the motor is the three-phase asynchronous motor, some types also uses a single-phase motors, but the three-phase motor is usually preferred. Different kinds of synchronous motor in some cases have their advantages, but for the most part, using asynchronous motor is more appropriate, and it is also the most economical choice. At the same time as the fixed speed operation and design of the engine is very popular, because some improvement with a higher reliability, better engine performance of inverter.
Controller
Variable frequency drive controllers usually uses solid state electronic power conversion equipment. Designed as a first input AC power into DC power, the use of intermediate bridge rectifier and converter. The rectifier is usually a three-phase full wave diode, intermediate on the DC power supply, and then converted into a quasi-sinusoidal AC power, control the inverter circuit. The inverter circuit is the most important one in the inverter circuit. Change into an alternating current three by AC motor energy-saving DC electric energy to use channel. These units are provided to improve the power factor, low harmonic distortion, low sensitivity of afferent phase control sequence than the frequency converter aging. The power input is converted to DC, and many units will accept single-phase and three-phase input power, however, when must reduce the use of the single-phase input unit only bridge rectifier connected component is carrying load.
The characteristics of AC motor applied voltage according to the requirement of the frequency change and make adjust, thereby providing the rated torque. For example, if an engine is designed for 460V, 60HZ, when the applied voltage must be reduced to 230V, frequency should be reduced to 30HZ. Per Hz V ratio must be regulated to a constant value. In order to obtain the best performance, sometimes need to further adjust the voltage, especially at low speeds. But sometimes this ratio is also changed, in order to change the engine torque. In addition to this control method, and other more advanced control method, such as vector control and direct torque control simple volts ( DTC ).
These methods in such a way that the adjustment of the flux and torque of the electrical machinery, which can accurately control the motor voltage.