The SD4S is the first member of the SD4x frequency inverter family from Sieb & Meyer.

© Sieve&Meyer

The new frequency inverters support interfaces and protocols such as Profinet, TNC or BiSS. Their central feature is the significantly improved processor performance: the built-in 32-bit ARM Cortex M7 processor from NXP is up to five times faster than the processors of the SD2x frequency inverters and therefore allows a higher resolution and more precise calculations. Sieb & Meyer has also switched from fixed-point to floating-point arithmetic, which allows for a more flexible design. "Overall, more complex tasks can be processed faster with the new processor system," says Torsten Blankenburg, Chief Technology Officer at Sieb & Meyer. A new FPGA from the "Spartan-7" product line from Xilinx is also integrated: it enables more complex control tasks to be processed. Sieb & Meyer has also significantly increased the memory compared to the members of the SD2x family - "with 500 times more memory, there will be no bottlenecks in the foreseeable future," says Blankenburg. "For the customer, this means a significant increase in performance: higher switching frequencies and improved control quality at even higher speeds result in improvements in the overall process."

Thanks to an integrated position controller, the SD4x devices can also perform high-precision positioning independently; speed and current controllers remain constant compared to the SD2x series. "Our aim is to drive high-speed motors dynamically and with as little power loss as possible," explains Blankenburg. "That's why we now also support PWM switching frequencies of 24 and 32 kHz." For even finer modulation of the sinusoidal signal, commutation angle control is now also integrated for 32, 48 and 64 kHz. "This results in an almost optimal sine wave, there are virtually no more harmonic currents," notes Blankenburg.

Usability has also been improved: the new "drivemaster4" version of Sieb & Meyer's parameterization software offers a four-part user interface. A watchlist makes it possible to subscribe to the parameters of several devices at the same time - "this is particularly useful for multi-axis applications", explains Blankenburg. A data logger also allows users to view and evaluate characteristic curves over longer periods of time.

The SD4S is designed for small high-speed spindles and motors in the power range of a few 100 W. Examples of applications include dental milling machines or machines for precision machining, such as those required in the watchmaking industry. Because the necessary insulation strength is often not provided in the motors of small spindles, the SD4S now enables galvanic isolation of the thermal contact. Blankenburg considers the width of just 40 mm to be an "absolute novelty".

Parameterization is carried out via a standard Ethernet interface, which replaces the USB interface that is prone to interference in industry. The SD4S also has parameterizable digital measuring system interfaces such as BiSS-C, EnDat2.2 and TTL. A web server enables technicians to call up device information without additional parameterization software. The real-time clock can be used to synchronize the time of an incident: for example, users can find out whether a thunderstorm has caused a failure.