Design and system analyses of canned switched reluctance drives for hydraulic pump applications

Switched reluctance machines (SRM) reach an increasing attention in the family of electrical machines because of the simple cross-section design while the rotor has no exciting sources like windings or permanent magnets. This geometrical simplicity results in lower manufacturing costs, lower maintenance efforts, more reliability and robustness. Due to these facts SRM are perfectly suited to drive hydraulic pumps under extreme environment conditions; either as a dry-running version or as a canned version for seal-less applications. To alleviate the understanding and the design process of a SRM the basic working and mathematical principles are described. Moreover, based on the fundamentals of electrical machine design an approach of the design process for SRM with respect to the converter and control method is given in general. Due to the complex design process of a SRM a stand-alone, analytical simulation tool for SRM either as dry-running or canned version is developed, which permits rapidly different steady-state and dynamic design analyses of the motor, of the power electronic as well as of the controller. Several machine configurations are received from steady-state electromagnetic and mechanical investigations and their dynamic behavior is optimized in detail under consideration of the supply source, the converter and the controller. Aside from the conventional used winding topology different winding topologies for SRM are analysed for both versions because the winding topology shows also a big impact on the drive performance, especially on the can losses, as well as on the acoustic noise emission. The measured performance characteristics of a 12/8 dry-running prototype are analysed and compared with the results of the analytical and finite-element investigations.