Deadbeat Flux Vector Control as a One Single Control Law Operating in the Linear, Overmodulation, and Six-Step Regions With Time-Optimal Torque Control

Abstract

This article proposes an enhanced version of the Deadbeat Flux Vector Controller (DBFC) as a one single control law which can operate in the entire torque-speed plane. The operation at any feasible modulation index can be accomplished by adequate determination of the flux trajectories at the different operating regions (e.g., PWM, overmodulation (I and II), and six-step). Continuous and seamless transition between the four operating regions is guaranteed, where the modulation index changes linearly with speed between PWM and six-step (without abrupt change in torque or acoustic problems). With the proposed strategy, undesirable torque dynamics, stability problems, and increased computational efforts associated with using multiple control laws are avoided. The transient performance of DBFC at the maximum voltage limit is analyzed in detail in the flux plane. A time-optimal torque control algorithm is developed to achieve the fastest possible torque dynamics and to considerably reduce the settling time, without the use of a voltage margin. The torque can be controlled with high accuracy and high robustness to machine parameter variations. With DBFC, no trade-off between good steady-state six-step behavior and good transient performance is needed due to the decoupling of switching and calculation frequencies. The proposed DBFC controller offers valuable features, and it is simple to implement. Simulation and experimental results are provided to validate the proposed control algorithm, which is implemented on an automotive microcontroller with a high-power/high-performance automotive traction machine (IPMSM).

Time-Optimal Model Predictive Control of Permanent Magnet Synchronous Motors in the Whole Speed and Modulation Range Considering Current and Torque Constraints

“…These methods are described in the following, classifying into methods that improve the transient performance and methods that improve the steady-state performance, i.e., enable the operation in the overmodulation range. Time-optimal controllers (TOC) [3][4][5][6][7][8] reach the operating point in the shortest possible time and, therefore, improve the control dynamics to its maximum extent. During transients, the time-optimal stator voltages (input trajectories) in the statorfixed frame are constant, see [3,4].…”

“…To prevent these undesired characteristics, the TOC methods [6,7] are considering current and torque limits but are restricted to the linear modulation range. The deadbeat flux control (DBFC) proposed in [8] is to the authors' best knowledge the only TOC method that can reach the entire overmodulation range. However, the DBFC [8] does not take into account current and torque limits leading to considerable undesired overcurrents and torque over-and undershoots.…”

“…The deadbeat flux control (DBFC) proposed in [8] is to the authors' best knowledge the only TOC method that can reach the entire overmodulation range. However, the DBFC [8] does not take into account current and torque limits leading to considerable undesired overcurrents and torque over-and undershoots.…”

“…This switching between different control strategies can lead to undesired transition shocks. Recently published methods [1,8,19,20] solve that problem by enabling an operation in the whole speed and modulation range including a seamless transition to six-step operation with a single control law. Here, only the DBFC [8] attains TOC performance as mentioned in the previous paragraph.…”

“…Based on torque step responses, the transient control performance of the proposed method is analyzed for different initial rotation angles ε(t = 0 s) and several stationary speeds. Additionally, a comparison with the methods proposed in [1] and [8] is conducted. The simulation and controller settings are listed in Tab.…”