SIEB & MEYER expands functional scope of SD4x family
Press releases
Sensorless Flying Restart for High-speed Applications
With Flying Restart, SIEB & MEYER expands the range of functions provided by drive controllers of the SD4x product family. The solution allows the drive controller to start operation while the motor or generator is still running, without the need for a sensor. This opens up new application fields for rotating systems that must quickly and safely return to controlled operation after an interruption.
Since the Flying Restart circuit is implemented via additional hardware for phase voltage measurement, the function will be available with selected devices of the SD4x product family in the future. At present, SIEB & MEYER plans to integrate the function in SD4M devices and later also in SD4S devices with 24 kW or more. With the sensorless Flying Restart function, a freely running motor or generator must not be decelerated to standstill after a short interruption before the operation can restart. The drive controller detects the rotor movement and restarts the operation of the motor or generator from the actual speed – a restart from speed zero, as required previously, is not necessary.
Relevant applications for Flying Restart
A typical use case is a generator application. If there is a temporary malfunction and the generator runs uncontrolled, the converter can restart controlled operation as soon as the normal operating conditions are restored. This helps to prevent unplanned downtime and ensures safe continued operation. Another particularly relevant application is a flywheel energy storage unit. Due to its high mass inertia, this system may rotate freely for hours or even days after loss of control. The Flying Restart function allows restarting the still rotating storage unit so that the process can continue without waiting time.
Efficient operation of synchronous spindles
Grinding machines with several synchronous spindles also benefit from the new function. If, for example, a spindle is turned off while another continues operation, the first spindle does not need to coast to a complete stop before restarting is possible. As long as the spindle runs at a speed above the specified minimum speed, the drive controller can reconnect with the running drive and put the spindle back into operation right away. This saves time and reduces unnecessary deceleration and acceleration processes.
The Flying Restart function is available from a speed threshold of 5 to 10 % of the rated speed. Below this threshold, the induced voltage is not sufficient for reliable speed measurement; the drive is then operated in the 'open-loop range'. In this case, users can also parameterize the behavior of the SD4x drive controller according to the specific application. Either the device decelerates the drive to standstill or waits until it reaches the required speed threshold for sensorless control again.