Combining circuit theory and numerical field calculations in designing mini-mechatronic systems

In mechatronic system design, electrical motors are generally treated by a lumped parameter model and a torque versus speed or versus position characteristic. In the design and optimisation of electrical machines and actuators, as generally used for powering such mechatronics systems, modern finite element based CAD methods are employed. In order to link both approaches, macroscopic parameters are deducted from the microscopic field solution via the appropriate post-processing methods. For normal sized motors, this is a well known approach. However, for mini- and micromotors, requiring a three dimensional field solution, this is far less evident. Therefore, a technique is described to derive the parameters and the torques from the magnetic field for the magnetostatic motors and the electric field for electrostatic motors. The inductances, resp. capacitances are calculated. For the torque not only the average component, but also the torque variations as a function of the position are discussed