Cross-coupling Magnetic Saturation Research Articles

Improved Current and MTPA Control Characteristics Using FEM-Based Inductance Maps for Vector-Controlled IPM Motor

Some major problems in the motor drive are the overshoot or undershoot of transient response characteristics and a parameter mismatch due to magnetic saturation. This study proposed a 3D inductance map combined with a maximum-torque-per-ampere (MTPA) map based on a finite-element (FE) motor model considering a cross-coupling magnetic saturation impact to overcome this problem. The proposed FE motor model has a high accuracy of no-load back electromotive force (e.m.f.) around 98.3% compared to the measurement results. Then, nine scenarios of vector control combinations of inductance maps and current supply variations of β 0°, 45°, and MTPA were investigated. As a result, the transient response improvement for β 0°, 45°, and MTPA without the map and with Ld and Lq maps is 63%, 10%, and 15%, respectively. Moreover, for the steady-state response, the average torque improvement between MTPA and Idref 0 A control is 9.21%, 8.97%, and 8.98% for the no-map, ave-map, and 3D-inductance-map conditions, respectively. The MTPA trajectory characteristic was also updated to illustrate the actual MTPA condition compared to the conventional MTPA control. In detail, the proposed method has reduced the parameter mismatch for the current control loop in the transient state and improved the MTPA control trajectory for the steady-state response. Finally, the improvement of vector control characteristics of the proposed method was verified by an FE simulation and experimental measurement results.

Improved Small-Signal Injection-Based Online Multiparameter Identification Method for IPM Machines Considering Cross-Coupling Magnetic Saturation

A novel online multiparameter identification method is proposed for interior permanent magnet (IPM) machines considering cross-coupling magnetic saturation. The identification method is based on the combination of small-signal impedance model and fundamental frequency signal model under <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axes. To analyze the nonlinearity of IPM machines, cross-coupling magnetic saturation effect is introduced into online multiparameter identification for the first time. Based on this model, a phase compensation strategy and orthogonal decomposition in phasor domain is proposed to decouple the complicated mathematical model into four linear equations. By injecting voltage small-signals into <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axes, multiparameter of IPM machine including adjusted apparent inductance, incremental self-inductance, incremental mutual-inductance can be identified online in a wide operation region. During this process, no additional computing equipment is required. The proposed method is carried out on a tested IPM machine and verified by the finite-element analysis.

An Optimized Time Sequence for Sensorless Control of IPMSM Drives via High-Frequency Square-Wave Signal Injection Scheme

This paper presents a filterless sensorless control scheme with an optimized time sequence based on high-frequency (HF) square-wave voltage injection for a five-phase interior permanent magnet machine (IPMSM) drive. To avoid the utilization of low-pass filters (LPFs) in signal processing, an effective method without filters is proposed in this paper. Moreover, the cross-coupling magnetic saturation is analyzed and the online position error compensation is applied based on the offline measurements and finite-element analysis (FEA). Besides, compared with the conventional time sequence of senseorless control, the proposed optimized time sequence can eliminate the additional position estimation error caused by the time delay in digital implementation. Numerical simulations and experiments with a 2-kW five-phase IPMSM are carried out. The results verify the feasibility and effectiveness of the proposed sensorless control scheme with an optimized time sequence adopted by the IPMSM drives.

Detailed description and analysis of the cross‐coupling magnetic saturation on permanent magnet synchronous motor

Permanent-magnet synchronous motor (PMSM) has obtained more attention, acquired more applications, and received great reputation due to its high torque density and simple structure. While exploiting its high torque capability, PMSM's control strategy faces great challenge at high overload scenario due to core-saturation effect. This study presents a detailed physical description and analysis on the effect of cross-coupling magnetic saturation in PMSM. Applying the conventional i d = 0 control strategy on a 1.5 MW surface mounted permanent-magnet synchronous generator, this study discusses the cause and influence of cross-coupling effect, presents the unbalanced magnetic permeance between direct -(d -) and quadrature-(q -)axis magnetic circuit. Either d - or q -axis electromotive force (mmf) would generate both d - and q -axis flux, especially those induced by permanent magnets. Then a permeance-fixed finite-element analysis is applied to separate the influence between permanent magnets and armature current. Finally, this study proposes a revised maximum-torque-per-ampere trajectory for surface-PMSM at high overload situation.

Novel Square-Wave Signal Injection Method Using Zero-Sequence Voltage for Sensorless Control of PMSM Drives

In this paper, a novel pulsating carrier signal injection strategy utilizing zero-sequence voltage is proposed for sensorless control of permanent-magnet synchronous machine (PMSM) drives. Different from the conventional zero-sequence carrier voltage sensing method using rotating signal injection in the stationary reference frame, the proposed pulsating injection is based on the estimated reference frame, which rotates anticlockwise at twice estimated rotor electrical angular speed. Then, the rotor position estimation is fulfilled via enabling the zero-sequence carrier voltage to zero. Compared with conventional rotating injection using zero-sequence voltage, the proposed strategy is simpler for signal demodulation and more robust to signal processing delays due to the fact that it is amplitude modulated by machine saliency and phase shifts of saliency position due to signal processing delays are intrinsically cancelled, which is the same as the classical pulsating injection in the estimated synchronous reference frame with carrier current sensing. Therefore, the proposed method can combine the synergies of zero-sequence method (i.e., high bandwidth and stability) and pulsating injection (i.e., increased accuracy and fast dynamic response). Furthermore, the cross-coupling magnetic saturation effects on zero-sequence voltage sensing-based sensorless control are discussed in detail. All the theoretical analyses are validated by experiments on a laboratory surface-mounted PM (SPM) machine.

Comparative Study of Novel Tubular Partitioned Stator Permanent Magnet Machines

Permanent magnet (PM) tubular machines have been applied to many applications, since they offer high force density with no end winding and no net attractive force between the mover and the stator. In this paper, two novel PM tubular machines named partitioned stator interior PM (PS-IPM) and partitioned stator surface-mounted PM (PS-SPM) tubular machines are proposed. Both the proposed machines are optimized for maximum thrust force, and their electromagnetic performance has been compared. It is found that the PS-IPM tubular machine has higher thrust force capability and better magnet utilization compared with the PS-SPM tubular machine. However, due to lower cogging force, the PS-SPM tubular machine has fewer thrust force ripples. Furthermore, the effect of the cross-coupling magnetic saturation on PM flux linkage, and the $d$ -axis and $q$ -axis inductances for both the proposed machines is investigated. It is demonstrated that the PM flux linkage and the $d$ -axis and $q$ -axis inductances are affected by the cross-coupling magnetic saturation. Moreover, the force–velocity characteristics of the proposed machines are calculated and compared. It is observed that both the machines have good constant power operation capability.

Novel Carrier Signal Injection Method Using Zero Sequence Voltage for Sensorless Control of PMSM Drives

In this paper, a novel pulsating carrier signal injection strategy utilizing zero-sequence voltage is proposed for sensorless control of permanent-magnet synchronous machine (PMSM) drives. Different from the conventional zero-sequence carrier voltage sensing method using rotating signal injection in the stationary reference frame, the proposed pulsating injection is based on the estimated reference frame, which rotates anticlockwise at twice estimated rotor electrical angular speed. Then, the rotor position estimation is fulfilled via enabling the zero-sequence carrier voltage to zero. Compared with conventional rotating injection using zero-sequence voltage, the proposed strategy is simpler for signal demodulation and more robust to signal processing delays due to the fact that it is amplitude modulated by machine saliency and phase shifts of saliency position due to signal processing delays are intrinsically cancelled, which is the same as the classical pulsating injection in the estimated synchronous reference frame with carrier current sensing. Therefore, the proposed method can combine the synergies of zero-sequence method (i.e., high bandwidth and stability) and pulsating injection (i.e., increased accuracy and fast dynamic response). Furthermore, the cross-coupling magnetic saturation effects on zero-sequence voltage sensing-based sensorless control are discussed in detail. All the theoretical analyses are validated by experiments on a laboratory surface-mounted PM (SPM) machine.

Improved Rotor-Position Estimation by Signal Injection in Brushless AC Motors, Accounting for Cross-Coupling Magnetic Saturation

This paper presents an improved signal-injection-based sensorless-control method for permanent-magnet brushless AC (BLAC) motors, accounting for the influence of cross-coupling magnetic saturation between the d- and q -axes. The d- and q -axis incremental self-inductances, the incremental mutual inductance between the d-axis and q -axis, and the cross-coupling factor are determined by finite-element analysis. An experimental method is proposed for measuring the cross-coupling factor which can be used directly in the sensorless-control scheme. Both measurements and predictions show that a significant improvement in the accuracy of the rotor-position estimation can be achieved under both dynamic and steady-state operation compared with that which is obtained with the conventional signal-injection method.

Modeling of Cross-Coupling Magnetic Saturation in Signal-Injection-Based Sensorless Control of Permanent-Magnet Brushless AC Motors

An improved brushless AC motor model is proposed for use in signal-injection-based sensorless control schemes by accounting for cross-coupling magnetic saturation between the d- and q-axes. The incremental self- and mutual-inductance characteristics are obtained by both finite-element analysis and measurements, and have been successfully used to significantly reduce the error in the rotor position estimation of sensorless control