High performance with synchronous reluctance motors
Synchronous reluctance motors – or SRM for short – and IPM synchronous motors are becoming increasingly widespread. Their speed-controlled, encoderless operation is based on the software in KEB’s new COMBIVERT S6 and F6 drive controllers.
“Our S6 and F6 drives operate all of the IPMs and SRMs on the market whether they have an encoder or not,” explains Helmut Fichtner, Head of Applications at KEB, in reference to this solution’s universal range of application.
While many SRM systems are made up of fixed motor/converter combinations, KEB goes a step further with encoderless operation based on precise detection of the rotor position. The important information is the current-dependent inductance in the d and q axes.
The peformance of the drive system is essentially determined by the quality of the drive controller but also depends on the design of the motor. Working in close cooperation with motor manufacturers results in economically attractive attributes that were only possible before, with more expensive motors with encoder systems. In concrete terms, this means:
- Full torque from starting point at n = 0 rpm
- Comparable overload or peak torques levels
- Full control in field weakening mode
The field of application for the SRM result from its high level of efficiency and the resulting positive energy balance. Examples are pump and fan applications or slowly rotating applications that do not require forced ventilation.
In addition to the standard approach to electrical variables, the KEB solution also features an exact image of the magnetic circuit, which even takes the saturation behaviour into consideration. The reluctance torque is established through precise knowledge of the saturation-dependent inductance sequences in the d and q axes of the motor as well as the resulting essential Id and Iq currents. This is how the system COMBIVERT S6 or F6 and the SRM facilitates particularly dynamic operation that was previously only seen in closed loop operation of synchronous and asynchronous machines.
A special identification method is integrated into the new Software for an easy commissioning process.