A case of perfection: High-frequency interference in interconnected drive systems

The BLOCK calculation tool taid achieves as yet unrivaled results when it comes to the development of  all-pole sine filters for the efficient, EMC-compliant design of variable frequency drive systems.

Communicatively linked electrical equipment and systems according to the Industry 4.0 standard are increasingly susceptible to common-mode and differential-mode interference as they are expanded. This is caused in particular by the switching processes of the rectifier and inverter bridges.  In addition, the ecological design requirements of EN 50598 demand a high degree of efficiency in the technologies and topologies used for filtering interference in interconnected drive systems and equipment. As the complexity of systems increases, so too does the cost of an optimized overall system design with reduced high-frequency common-mode or differential-mode interference. With the help of taid, we are developing the ideal components for EMC-compliant designs of variable frequency drive systems.

Solution for more power quality – all-pole sine filter SF4


Improved EMC 

If high frequencies are to be expected in the currents, it is recommended to use a 4-pole inductor with capacitance in a filter application like an all-pole sine filter. We take the all-pole sine filter SF4 as the basis for such a filter solution. The all-pole sine filter reduces the differential-mode and common-mode interference at the frequency converter output and enables long motor cable lengths. By minimizing high-frequency interference currents and bearing currents, EMC problems can be eliminated from the system. 

Improved efficiency

By using an all-pole sine filter, considerable improvements in efficiency can be achieved for the entire system: of up to 24% when at partial load and of more than 50m, i.e. 5%, at nominal load when longer motor cables are used. At the same time, the entire frequency range can be utilized by expanding the operating range to ≥4 kHz clock frequency at 500 V output voltage and a rotary frequency up to 150 Hz. This means a considerably more efficient and space-saving solution for variable frequency drive systems. 

Fast and optimized designing – taid for 4-pole inductor calculations

For the fourth pole of the 4-pole inductor that we recommend as an all-pole sine filter, we use a further, thinner core material, because common-mode interference has higher frequency elements. Standard calculation software solutions are therefore no use for the design of this filter solution. The finite element method available for this delivers a world-renowned reliable result with calculation times of up to 3 hours per inductance. For optimal, customer-specific designs, BLOCK uses its own developed software taid ein.

For an application-specific, optimized design, we calculate the saturation behavior of the core materials and the magnetic dimensions for non-linear properties. Taid significantly reduces the calculation times to a few seconds for both common mode and differential mode. Furthermore, the values calculated by taid for the effective dimensioning of inductance in common mode and differential mode are even more comparable to the actual measurement results. Therefore, in practice, if combined with a standard solution, multiple customer-specific variants can be calculated in just a short time to find the ideal design for the entire system. 

Calculation times for the differential-mode inductance
calculation method time (hh:mm:ss)
FEM-Simulation 02:23:51
New Approach 00:00:03
Comparison of the measurement results of the effective inductance in the differential-mode scenario with calculations
Comparison of the measurement results of the differential inductance in the common-mode scenario with calculations

Find out more about taid in the expert interview with Michael Owzareck

Taid calculation for all-pole sine filters – the quick way to optimized EMC

For complex, interconnected drive systems, all-pole sine filters offer increased efficiency for frequency converter, motor cabling and motor, independent of load. Use of an all-pole sine filter not only increases the level of efficiency in the entire system, but also provides a space-saving solution for compact and interference-free applications according to the Industry 4.0 standard. BLOCK supports the design process for EMC-compliant variable frequency drive systems exclusively with taid.  Compatible with a wide standard portfolio, taid enables a size- and efficiency-optimized filter topology to be developed with the customer in just a short time. Quicker and more precise, from prototype simulation to finished product. Taid combines speed and precision for the calculation of specific filter topologies down to perfection.


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