Application of new energy-saving soft starter (DWR series)

Single chip microcomputer STM32L151CCU6

L0504-Murata muRata common mode inductor 90Ω 150mA

MOS power IC full range

Energy conservation is China's basic national policy. The state has formulated a special medium- and long-term plan for conservation. The energy-saving project of electric motor system is one of the key points. Therefore, energy conservation and consumption reduction to improve production efficiency is the goal pursued by every enterprise. One is to reduce the starting current, and the other is to take reactive power compensation to achieve energy saving. The best way to reduce the starting current is to adopt variable frequency speed control technology and soft start technology. Since the price of frequency conversion equipment is relatively expensive, the price is lower now, but it is still very expensive compared with the price of soft starter. In the case, it is more economical to choose a soft starter, so the soft starter is quickly promoted. This article focuses on a DWR series energy-saving soft starter.

Characteristics

The new DWR series energy-saving soft starter adopts advanced digital circuit, which is more stable and reliable. The main circuit is equipped with high-voltage value and powerful power device installation. It has strong anti-overvoltage overload capability, increases frequent starts and stops, cuts no arc phenomenon, and prolongs the use of equipment. Lifetime; its specific characteristics are as follows: ● Energy saving, smooth start, no impact on the power grid and equipment, reducing power distribution capacity and improving production efficiency. ● Installation has no phase sequence requirements, but phase sequence protection can be set. ●Starting voltage O~80%, starting time 2~6O seconds, arbitrarily adjustable. ● Ramp voltage start, ramp voltage plus kick start, ramp voltage plus current limit start, multiple start modes are optional. ● Complete protection function, white fault diagnosis, reliable shutdown for phase failure, serious three-phase imbalance, phase sequence, overcurrent, overheat, overvoltage and undervoltage. ● Free stop and soft stop can be selected arbitrarily. The soft stop can effectively avoid the pressure shock of the high-rise water supply to the pipeline. ●The control circuit adopts industrial single-chip photoelectric isolation and digital structure, strong anti-interference ability, and can work normally under harsh working conditions. ●High reliability, long service life, low failure rate and saving maintenance costs.

working principle

The principle block diagram is as shown in the above figure. The whole soft starter is composed of three circuit boards and the main circuit. The working principle is that the three-phase 380V power supply is stepped down to the IOV low-voltage power through the isolation transformer of the power supply board, and is rectified through the three-phase rectifier bridge. The filter provides DC working power for the power board, control board, and digital display board. It also provides a synchronous signal source for the control board. The other three-phase low-voltage 8V of the power board is rectified and divided, and the synchronous signal and the driving trigger signal sent by the control board are used to trigger the thyristor and change the conduction angle of the thyristor to achieve the purpose of voltage regulation. The control board mainly consists of STC89C52 industrial single-chip microcomputer, optocoupler, semiconductor resistor-capacitor and IC integrated circuit, which are composed of rectification, digital filtering, counting, oscillation, clock, pulse signal generation, double pulse signal synthesis and other functional circuits. The board provides a synchronous drive signal to provide a digital display signal to the digital display panel, and the digital display panel provides programming signals for the control board. The main circuit consists of 6 high-power high-withstand voltage unidirectional thyristors (the thyristor can also be used with the MTC-type thyristor module to reduce the volume and easy to install), temperature sensor, varistor and current transformer. The main function of the RT1, RT2, and RT3 varistors is to absorb the instantaneous pulsating surge spike voltage of the main circuit.

Kit installation

The whole energy-saving soft starter kit includes a central controller and a main circuit. The internal structure of the central controller includes all control parts such as a digital display panel, a control board, and a power board. For the connection between the center controller and the main circuit, refer to the above figure. The main circuit is divided into two types: modular and discrete. This article focuses on the modular type. Firstly, the internal anti-parallel of the MTC type should be selected. The withstand voltage value is 1400V, and the withstand voltage between the heat sink and the electrode should be above 3000V. Silicon control module, current and heat sink selection must be calculated according to the power of the motor, generally available motor power (KW) × 4 (coefficient) = A (module current) heat sink 15KW-37KW optional SRX-CCK size 330 × 287×30, power 40-75KW selected SRX-CEH size 365×23O×26, power 90KW-l60KW selected SRX-CHI size selected 475×3Ol×52) above size in millimeters (200-500KW selection tablet controllable Silicon) The above data is for reference only; the heat sink should be smoothed by the milling machine, and it should be black-plated. When installing the module, apply a layer of insulating thermal grease to facilitate large-area contact and evenly press it.

One drag three type of thyristor can be appropriately increased by one gear, the heat sink can be unchanged, detailed installation essentials can refer to the main circuit installation chapter of the user manual.

Function setting

The function data is set at the factory and can be used directly by the user. If the user needs to modify the function settings according to the actual situation, you can press the following operation method: first press the setting button, refer to the function code setting table of the product manual to select the required function code, press the plus and minus keys as needed, and adjust Go to the required data, press the enter key after the adjustment is completed.

use

When using, input terminal R, S, T terminal to connect 380V power supply, output terminal U, V, W terminal to load (use 220V/200W bulb Y to replace the load), press the start button, then the bulb should be gradually darkened Bright light) Observe the same brightness of the three bulbs, use the universal meter to measure the output voltage and the same as the input power supply to prove that everything is normal, cut off the power supply) remove the three bulbs) and then connect the load motor to work. According to the load situation, the starting voltage and the starting time can be appropriately selected. Generally, the starting voltage of the empty load should be selected at about 10%, and the starting time can be selected for about 10 seconds.