Efficiency of organizing systems with variable frequency drives

A large number of industries today use electric motors in their processes (more often asynchronous, but there are also synchronous motors). They allow enterprises to significantly save on labor: human work is not required to create a movement – mechanical energy is obtained by converting electrical energy/ =readmore=/ The development of technologies, understanding of the features of the interaction of elements in certain production systems contributed to the realization of the possibility of achieving even greater savings in enterprise resources when using electric motors

For each task of creating motion, it is necessary to have its own rotor speed of the electric machine. For a long time, all kinds of units with engines were assembled in such a way that there was no possibility of changing their mode of operation when changing the values of any system parameters. by attaching an abrasive wheel to the shaft of an asynchronous motor. With this device, it is possible to cut off part of the material from the workpieces (for example, when sharpening knives), but it is difficult to make fine, accurate polishing, since it requires a decrease in speed. To reduce the rotor speed, it is necessary to change the frequency of the supply alternating current, but it is constant in household networks – 50 or 60 Hz You can change it by including a frequency converter – a device that allows you to transform the frequency of alternating current (approximately in the range of 1 & ndash; 800 Hz) With the installed frequency converter, you can adjust the engine speed The range of work performed on the grinder is thus expanded

The economic meaning of using a frequency controller in the above example is to gain the ability to perform a large number of jobs on one machine without the need to spend time, effort, materials and money on making a tool for each task

In industrial-scale production operations, the same relationship can be traced. So, electric motors are used in pumping units at stations for supplying water to the central water supply system. A pump without a frequency controller takes water from a source and increases its pressure (D1) by some constant value (P) in accordance with the once set operating mode The output is increased pressure (D2), the value of which is equal to the sum of the value of the water pressure in the source and the value added by the pump When D1 = 0.5, P = 1, the pressure D2 is equal to 1.5 The conditional water supply network cannot withstand the conditional pressure D2 = 1.5 for a long time. But the increased pressure D2 is compensated by the consumption of water by network subscribers, as a result of which the pressure drops to a certain acceptable level, for example, to (2/3 × D2), t e Up to 1In this case, there will be an increased pressure in the system, which contributes to the rapid wear of its elements (for example, stuffing box seals) And if the inlet pressure D1 is equal to 1 and the pump adds the unit set as a constant, the pressure D2 will be equal to 2, which threatens the conditional water supply system with even greater breakdowns

The problem can be solved by the established combination of the frequency and PID controller. The latter will receive information about the current values of D1 and D2 and, in accordance with them, generate a signal for changing the engine operation mode by the frequency controller in order to maintain the output pressure at an optimal level. This mode of the system can be call situational

Thus, the introduction of systems with variable frequency drives allows enterprises to save resources: electricity consumption is reduced as a result of the situational operation of electric machines, the costs of replacing and repairing other equipment are minimized (the need for them arises when wear occurs, which is a consequence of the operation of elements in non-situational mode)