Search

For hybrid-excited doubly salient synchronous machine, both the field excitation current and the d-axis current can be utilized to adjust the flux-linkage, which provides more flexible control parameters for flux-weakening operation. In this paper, three flux-weakening control methods, i.e., utilizing field excitation current alone (Method I), utilizing armature current alone (Method II), and optimal method (Method III), are proposed and compared. All three methods can achieve similar torque performance in the constant-torque region. In the flux-weakening region, Method I exhibits low torque and limited operating speed range. The operating speed range can be further extended by Methods II and III. In addition, Method III can provide a higher efficiency in flux-weakening region than Method II since the copper loss of field winding can be decreased in proportion to the reduction of field excitation current. Those flux-weakening control methods are verified by experimental results. [ABSTRACT FROM AUTHOR]

Hybrid‐excited permanent magnet (PM) machines utilise the coordinated operation between the PM and the field excitation current. To enhance the effectiveness of the field excitation current, iron flux bridges are applied to hybrid‐excited switched‐flux PM machines. This study proposes a new control strategy in which the d‐axis current is utilised, while the field excitation current is controlled towards zero rather than negative in the flux‐weakening mode. These reference currents are determined by the voltage error regulation method. The special magnetic circuit can effectively reduce the d‐axis flux‐linkage by either partially short‐circuiting the PM flux via the iron bridge or removing the field excitation current. The proposed method exhibits advantages, such as highly enhanced torque response in the constant torque region, extended speed range, robustness against machine parameters, and higher efficiency in flux‐weakening region. The feasibility of the proposed method is verified by detailed experimental results. [ABSTRACT FROM AUTHOR]