KEB Promotes High-RPM Servo Motor Health via the Z2 Sinusoidal Filter
KEB Automation has introduced Z2 Sinusoidal Filters to control and optimize the servo control loop for high-speed systems, leading to longer service life for the equipment.
Drive motors inherently introduce high-frequency components in the rapid on/off nature of pulse width modulation control. The high-frequency components are often a result of the switching frequency, which is how fast the signal moves from on to off.
What is the Purpose of the Filter?
The new Z2 filter from KEB Automation allows for a ‘cleaner’ sine wave to be sent to the motor control. This optimizes the stability and control of the servo system and does not introduce extra loss to the motor’s stator and rotor. The Z2 and sibling Z1 models can operate with output frequencies in the range of 50 Hz, 100 Hz, 200 Hz, and up to 1,600 Hz.
The Z2 filter can be paired with KEB’s internal Combivert S6 servo drive and Combivert F6 drive controller and serves as a low-pass filter. On the motor side of the servo control loop, the high-frequency drive controller signal components are attenuated.
The new Z2 sine-wave filter. Image used courtesy of KEB Automation
Why Use a Z2 Filter?
There are many benefits to utilizing the Z2 sinusoidal filter in application. The primary advantages are increased efficiency and reliability of the system. Within the motor, rotor heating is minimized by the reduction of current ripple from the filter. In turn, the service life of the associated bearings also benefits from a reduction in high-temperature environment conditions.
Preventative maintenance cycle timelines can be widened, and the system will operate more optimally. On a tactile level, the mechanical noise of the motor is mitigated. Lastly, the use of a filter has many electrical benefits to the system. The sinusoidal signal generates less voltage, which eliminates excess voltage at the motor winding. Furthermore, the filter can reduce capacitive or discharge current in the system and overall reduce the electromagnetic compatibility (EMC) effects on the system, notably interference.
The recreation of various frequency sinusoidal waves from a pulse width modulation output. Image used courtesy of KEB Automation
Applications of the Z2 Filter
There are many industries that may benefit from the Z2 filter. In industrial automation, assembly lines or machines utilizing robotics would be a prime use case. The OEE of assembly lines, packaging automation, etc., would likely be improved by the smoothing effect of the filter on the servo motors driving plant motion and productivity. Specific high-speed target applications also include turbo blowers and compressors like those found in mining, power, and downstream oil & gas industries.
An example of a turbo compressor that would benefit from the Z2 filter. Image used courtesy of Howden
Another potential industry is machining. CNC machines could achieve higher tolerances on machined parts due to the increased stability in motor control. The same benefits of reliability could carry over as well to provide increased machine uptime. Other examples include the textile and semiconductor industries. Precision robotics used in these industries to thread fabric and handle wafers could benefit from the sinusoidal filter.
The fundamental sinusoidal PWM waveform utilized by the new Z2 from KEB has a profound effect on many industries outside of industrial automation. It’s a clever solution to optimizing electro-mechanical systems.
