The method of field-oriented control is used to operate an AC machine efficiently and with high performance. For field-oriented control it is necessary to know the rotor position especially for synchronous machines. The rotor position can be determined by either using a position sensor or a sensorless control scheme, which calculates the rotor position according to the measured current and applied voltage.
Basically there are two different classes of methods for sensorless control. First there are the fundamental based schemes, in which the rotor position is determined by the induced voltage of the rotor. These methods are easy to apply, but are not suitable for the full speed range, as the induced voltage vanishes for zero speed. Simple sensorless control methods therefore use an open loop startup. The other type of methods is represented by algorithms based on magnetic anisotropy. These methods are complicated in application and thus not yet widely spread. Anisotropy methods, however, are not restricted to a certain speed range.
Bitflux uses a patented method to calculate the rotor position. This method requires very little computational effort and offers a high performance sensorless control, which exceeds the characteristics of an incremental encoder in terms of dynamics and differential accuracy.
To reliably detect the rotor position even at a standstill, it is necessary to inject high frequency voltage pulses in the machine. However, these voltage pulses cause noise. Using the Bitflux method makes it possible to reduce this noise to a minimum, or even to shift it to an inaudible range for some applications.
Yes, that is possible. It is much more efficient to use a reluctance synchronous machine, especially for applications which used induction motors with position sensor so far.
As soon as more than one machine is connected to one inverter, it is no longer a case of closed loop control. Basically it is possible, but it will lead to significantly reduced performance and efficiency for the single machine.
The hardware can remain unchanged and no additional components are required. The implementation of the algorithms uses small resources of the drive controller. The exact scale is individually different and depends on the desired functionality.
After a preliminary investigation to check the suitability of your systems (motor and electronics) for our sensorless control method, Bitflux provides a precompiled version of dynAIMx®, which you’ll integrate in your existing control.
You’ll receive a precompiled test version from us, which you’ll integrate in your existing code within your development environment. By means of the supplied documentation, the integration of dynAIMx® will be completed within a week.
We are focused on the control of all synchronous motors, including the highly efficient and dynamic permanent magnet synchronous machine (also including EC-motors) as well as the cost optimized reluctance synchronous machine. However, not any type of synchronous motor is equally suitable for control with dynAIMx®. Hence an individual assessment of the motor is advisably.
Basically, the inverter needs a current measurement in at least two channels. However, how well the software works is to be figured out individually and depends on the requirements of the application.