Control System Commissioning of Fully Levitated Bearingless Machine

Abstract

The bearingless permanent magnet synchronous motor (BPMSM) is a compact motor structure that combines the motoring and bearing functions based on well-designed integrated windings for generating both torque and magnetic suspension force. In order to achieve a successful high-performance control design for the BPMSM, an adequate model of the rotor dynamics is essential. This paper proposes simplified multiple-input and multiple-output (MIMO) control approaches, namely the pole placement and the linear-quadratic regulator (LQR), that allow to carry out identification experiments in full levitation. Additionally, the stability of the MIMO levitation controller is verified with the rotation tests. Compared with other recently published works, the novelty of this paper is to experimentally demonstrate that a stable fully levitated five-degrees-of-freedom (5-DOF) operation of a bearingless machine can be achieved by the proposed approach, and thereby, options for commissioning of such a system are obtained.

Adaptive MIMO pole placement control for commissioning of a rotor system with active magnetic bearings

“…This corresponds to an eigenvalue of a spring-damper-mass system with negative stiffness. A similar tuning rule has been applied in [15], [1] for bearingless machines. In this paper, the third-order design polynomial is considered to achieve the desired dynamics for the closed-loop controller…”

“…The proposed adaptive control law is studied by simulations by considering a bearingless machine [1] as an example case of a high-speed machine with a magnetically levitated rotor system. First, a system model with rigid dynamics is modeled, and then, a pole-placement-based state space control law is designed.…”

“…The 11-cell PRBSs are injected to all the control inputs with an amplitude of 0.75 A. The same amplitude has been used for SISO identification purposes in [1]. The poles of the position control are placed using a design function 3 − 2.8852 2 + 2.7721 − 0.8869, and the state observer is designed to be eight times as fast.…”

“…Typically, the initial control synthesis of a high-speed motor with a magnetically supported rotor system is based on the modeled dynamics of the AMBs combined with the flexible rotor system obtained from the analytical tools applied in the design phase [1]. After a stabilizing controller for levitation has been obtained, the control design procedure turns into an iterative identification of a control problem.…”