The series-parallel hybrid electric vehicles (HEVs) are widely developed due to the advantages of high fuel economy and good driving performance. The electronic continuously variable transmission, which is a key part of the HEV, can be based on planetary gear or compound structure machine (CSM). The axial magnetic-field-modulated brushless double-rotor machine (AMFM-BDRM), which can be connected with a traditional permanent-magnet synchronous machine to form a CSM, is investigated in this paper. The axial tilting torque is analyzed, and the necessary condition for avoiding it is given. Compared with the single-sided topology, the double-sided AMFM-BDRM is recommended to eliminate the axial tilting torque. The influences of winding turns, diameter ratio, ferromagnetic block and permanent-magnet (PM) dimensions, air-gap length, phase current, and internal power-factor angle on the power factor and electromagnetic torque are analyzed, and it is found that the increase of power factor is sometimes at the expense of sacrificing the electromagnetic torque. The effects of speed and PM segmentation on losses are investigated, and the circumferentially double-segmented PM is selected. The influences of dissymmetry on air-gap flux density, no-load back electromotive force, electromagnetic torque, and axial magnetic force are analyzed, and it is found that the offset, tilt, and PM position deviation of the PM rotor have different degree effects on machine performances. Experiments are carried out, and the correctness of the analysis and simulation results are verified.

With the advantages of good driving performance and high fuel economy, the series-parallel hybrid electric vehicles (HEVs) are widely developed. Power-split device, which is a kernel part of HEV, can be based on planetary gear or compound-structure machine (CSM). The transverse-flux brushless double-rotor machine (TF-BDRM), which can form a CSM by being connected with a traditional permanent-magnet synchronous machine (PMSM), is investigated in this paper. The equivalent magnetic circuits are established, and the equivalent reluctances, and d- and q-axis armature-reaction reactance are deducted. It is found that the armature-reaction reactances are in direct proportion to pole-pair number. The reluctances of stator core, inner and outer air gaps, transverse-flux (TF) tooth and leakage reluctance are analyzed. Flux-concentration structure is investigated to increase the main flux of the machine. Flux-concentration factor EFC is used to illustrate the effect of flux-concentration structure, which can be increased by the increase of the radial and circumferential thickness of PM. The flux-density distributions of two typical situations are simulated. With manufacturing technology investigated, the TF-BDRM prototype is made, and experiments are carried out. The tested waveforms of BEMF are approximately sinusoidal, and the tested torque ripple is obvious.

The magnetic-field modulated brushless double- rotor machine (MFM-BDRM) is a promising candidate for the power splitting device in hybrid electric vehicles (HEVs). Due to its special operating principle – the magnetic field modulation principle, various harmonic magnetic fields are produced in the MFM-BDRM. Therefore, it is very crucial for the design of MFM-BDRM to reduce the influence of non-working harmonic magnetic fields on the electromagnetic performance of MFM-BDRM, like back electromotive force (EMF) and torque ripple. Firstly, the distribution law of PM and armature modulated magnetic fields is analyzed. Secondly, since the analysis and calculation method of harmonic back EMF in traditional PM machine is not suitable for the MFM-BDRM, the formation mechanism of harmonic back EMF in the MFM-BDRM is further investigated. Thirdly, Combined with the characteristic of modulated magnetic field and formed harmonic back EMF in the MFM-BDRM, the optimal pole pair combination of stator, PM rotor and magnetic blocks is investigated. Finally, Analysis and calculation of a specific MFM-BDRM by analytical and finite element method shows the MFM-BDRM with the optimal combination can obtain very sinusoidal no-load and load back EMF and quite low torque ripple.

Current-source inverter is considered as a promising candidate in the permanent-magnet synchronous machine drive system for its superior current waveforms and inherent capability of withstanding the short-circuit failure. However, the resonance issue is yielded, resulting from the paralleling of machine inductances and filter capacitors. Very limited control bandwidth can be retained if only considering the passive damping of winding resistance. In this article, the decoupled active damping current controller in the synchronous frame is investigated. The impedance analysis is performed to make a more intuitive demonstration on the damping mechanism, which reveals that the virtual impedance is not always linearly correlated with the damping gain. The digital delay is crucial for the accurate assessment on the damping effectiveness, and the z -domain discrete model is established to emulate the real circumstance. The quantified analysis is performed on deriving the stable boundaries of controller parameters. The frequency responses and root trajectories are illustrated to validate the conclusions. The optimized parameters are obtained by the proposed tuning procedure, which realizes a balance between the damping effect and the bandwidth performance. Finally, the experiments are performed to verify the proposed control schemes.

Current-source inverter (CSI) is considered as a prospective solution for modern machine drives, for its higher reliability and superior harmonic suppression. The open-circuit fault-tolerant control for five-phase CSI-fed permanent magnet synchronous machine drive with pentagon winding connection is investigated. The switch open-circuit fault and winding open-circuit fault are studied. For the switch open fault, three cases are discussed including single-phase, adjacent two-phase, and nonadjacent two-phase faults. It is indicated that in pentagon circuit, despite the switch of fault phase is disabled, the corresponding phase winding is still connected in the end-to-end power circuit and contributes for torque generation. The new sets of coordinate transformation are proposed, and the mathematical modeling is presented. The fault-tolerant space vector modulation techniques are proposed based on the reconstructed vector planes. In addition, the single winding open fault is studied, which is a specific fault case and breaks off the closed pentagon connection. An important conclusion is derived that the pentagon winding connected CSI gains inherent fault-tolerant capability against the single winding open circuit. The control algorithm even does not need to be switched during this typical fault. Experiments are performed on verifying the proposed schemes.

Despite the merit of fast dynamics, deadbeat predictive current control (DPCC) suffers from the dc and ac disturbances. To address the issue, active disturbance rejection control (ADRC) has been proposed, including the conventional and composite ADRC schemes. However, the conventional ADRC cannot suppress the ac disturbance effectively. While in the composite ADRC, the performances of the current control and disturbance suppression loops are coupled, distorting the deadbeat properties of the DPCC. In addition, both schemes are subject to weak capability in tracking the fast time-varying disturbance. To solve the problems, this article proposes a decoupled ADRC based on the composite disturbance observer, where the second-order disturbance extended state observer (SDESO) and quasi-resonant controller (QRC) are employed to suppress the dc and ac disturbances, respectively. Compared with the composite ADRC, the proposed scheme can fully decouple the performances of the current control and disturbance suppression loops, and thus deadbeat properties can be retained. In addition, by the SDESO, the proposed scheme enables superior dynamic performance in tracking the time-varying disturbance. The system stability and anti-disturbance capability of the proposed scheme are analyzed in detail. Finally, the effectiveness of the proposed scheme is validated on a 0.55kWPMSM platform.