The selection of Weidmüller power supply variable frequency power supply (types of variable frequency power supply) The correct selection is essential for the normal operation of the electrical control system of mechanical equipment.When choosing a variable frequency power supply (knowledge of variable frequency power supply), the factors and points we have to consider are also various.So, in the selection process of variable frequency power supply, which aspects should we considerMany people may not understand this.In view of this, Jinan Nenghua made a detailed summary on the consideration factors and key points of selecting variable frequency power supply by collecting and collating data..
Selection principle of variable frequency power supply (purchase of variable frequency power supply)
First of all, according to the type of mechanical equipment, load torque characteristics, speed regulation range, static speed accuracy, starting torque and the requirements of the use environment, and then decide which control mode and protective structure of the frequency conversion power supply is most suitable.The so-called combined use is to achieve the best cost performance for variable frequency power applications under the premise of meeting the actual process production requirements and use occasions of mechanical equipment.
Factors to be considered in the selection of variable frequency power supply
When using variable frequency power to select speed regulation, it is necessary to consider various aspects such as process requirements, saving benefits, and investment payback period.If only considering the process requirements and saving benefits, it is more advantageous to use variable frequency speed regulation in the following situations:
○According to the process requirements, the production line or single equipment needs to adjust the motor speed according to the procedure or according to the requirements.Such as: packaging machine transmission system, according to different types of products, the transmission speed of the system needs to be changed, and the use of frequency conversion speed control can make the speed control system simple, accurate, and easy to achieve program control.
○Use frequency conversion speed control instead of mechanical speed change.Such as: machine tools, not only can eliminate complex gearboxes, but also improve racing speed and meet program control requirements.
○Use variable frequency speed regulation instead of using gates or baffles to adjust the flow, suitable for fans, pumps, compressors, etc.For example: the boiler water pump, blower, and induced draft fan have implemented variable frequency speed control, which not only eliminates the servo amplifier, electric operator, electric actuator and water supply valve (or wind baffle), but also makes the entire boiler boiler control system get Fast dynamic response, high control accuracy and stability.
The protection circuit inside the power supply monitors every move of the power supply and is the brain of the power supply.It is responsible for starting the power supply and monitoring and adjusting the voltage/current. At the same time, it automatically protects when there is a short circuit, open circuit, overvoltage, overcurrent, undervoltage, undercurrent, etc..Inferior power supplies usually simplify this part of the circuit or even no protection circuit at all, and all this will bring many hidden dangers to the PC system.
According to the position of the protection circuit and the type of monitoring, the internal protection circuit of the power supply is divided into four types: input overvoltage protection, input overcurrent protection, output overvoltage protection and output overcurrent protection, which are also most of them. The origin of the “quadruple protection circuit” promoted by high-quality brand power.As the name implies, the over-voltage/over-current protection circuit is automatically effective when the monitored input/output voltage/current is abnormal, so as to achieve protection..
In addition, high-quality power supplies are usually provided with output short-circuit protection.This is a very useful feature.
The working process of the switching power supply is quite easy to understand. In the linear power supply, the power transistor is operated in linear mode. Unlike the linear power supply, the PWM switching power supply allows the power transistor to work in the on and off state. In the state, the volt-ampere product added to the power transistor is very small (when it is turned on, the voltage is low and the current is large; when it is off, the voltage is high, and the current is small) / the volt-ampere product on the power device is the power semiconductor Loss in the device.
Compared with the linear power supply, the more effective working process of the PWM switching power supply is achieved by “chopping”, that is, the input DC voltage is chopped into a pulse voltage whose amplitude is equal to the amplitude of the input voltage.. The duty cycle of the pulse is adjusted by the controller of the switching power supply.Once the input voltage is chopped into an AC square wave, its amplitude can be increased or decreased by the transformer.The output voltage value can be increased by increasing the number of secondary windings of the transformer.Finally, after these AC waveforms are rectified and filtered, the DC output voltage is obtained..Weidmüller power supply
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