EN 
UA 
RU Fan control systems are perhaps the most popular application. Therefore, the installation of frequency converters in these systems is very popular. After all, fans are mechanisms that strongly require speed regulation.
Since the air resistance changes not directly proportional to the motor speed, but according to a quadratic, cubic, or other dependency, the frequency converter itself must be able to work with these relationships. Why is this important? Because power consumption directly depends on it. And since ventilation occupies a large number of applications and usually uses powerful motors (especially in industry) and often operates 24/7, every saved kilowatt-hour per year provides significant savings without affecting productivity or the motor. The main recommendations and functions with which a frequency converter should be equipped to work with fans.
Support for scalar control. As a rule, all converters support this mode. Its essence is maintaining the ratio U/f n=const (where n≥1). Maintaining a constant magnetic flux is the main task of this control algorithm. This solves the issue of smooth start, regulating the motor shaft speed without complex measurements and calculations. And feedback on speed is not required. Therefore, this control method is an economical and effective method for controlling asynchronous motors. Because here you only need a change of speed, but there are no high requirements for dynamics and accuracy. That is, fans, compressors, pumps, and so on.
The ability for coast braking, meaning that upon sending a stop command to the frequency converter, it simply cuts off the voltage and the fan stops by inertia. This way, there is no energy generation to the converter, thus preventing the frequency converter from failing.
And most importantly, the ability to set different values of n in maintaining the ratio U/f n=const. Also, the ability to set a custom operating curve – that is, a set of points where a certain voltage corresponds to a certain frequency. The more points you can set, the more accurately the curve can be formed. And here frequency converters vary greatly in this setting. And this is a very crucial point. Let's look at these values using the example of different frequency converters from different manufacturers:
| Brand | Series | Values of n for the law U/f n=const | Number of points for forming the custom curve |
| Schneider Electric | ATV320 | 1;2 | 5 |
| Schneider Electric | ATV630 | 1;2 | 5 |
| Schneider Electric | ATV610 | 1;2 | 5 |
| Delta Electronics | VFD-E | 1;2 | 3 |
| Delta Electronics | MS300 | 1;1.5;2 | 4 |
| Delta Electronics | CP2000 | 1;1.5;2 | 4 |
| INVT | GD20 | 1;1.3;1.7;2 | 4 |
| INVT | GD27 | 1;1.3;1.7;2 | 4 |
| INVT | GD200 | 1;1.3;1.7;2 | 4 |
| VEICHI | AC01 | 1;1.1;1.2;1.3;1.4;1.5;1.6;1.7;1.8;1.9;2 | 5 |
| VEICHI | AC10 | 1;1.1;1.2;1.3;1.4;1.5;1.6;1.7;1.8;1.9;2 | 5 |
| VEICHI | AC310 | 1;1.1;1.2;1.3;1.4;1.5;1.6;1.7;1.8;1.9;2 | 5 |
Let's analyze the data. The greater the ability to configure n, the more optimal the curve can be selected and the more optimal energy savings can be achieved. The number of points to form the custom curve – the more points, the more optimal and energy-saving the curve can be formed. When adjusting the fan operation by the parameter n, it is necessary to select such that the motor current during operation is minimal. Therefore, the greater the options for selecting the parameter n, the more optimal power consumption can be achieved. Based on the comparison table, it is clear that the undisputed leader is the manufacturer VEICHI. Moreover, all series have this capability, even the most budget-friendly AC01 series.
The Chastotnik team has extensive experience implementing frequency converters in various industries. Contact us for consultation, selection, and assistance in commissioning.