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The field-winding-induced voltage pulsation in the doubly salient brushless dc (DSBLDC) generator leads to the field current ripple and challenges the dc power supply for the field winding. In this article, a new DSBLDC generator with stator-damper winding is proposed to reduce the induced voltage in the dc field winding. The stator-damper winding configuration is illustrated. The winding self-inductance and coupling characteristics are investigated. The influence of the allocation and dimension of the damper winding on the induced voltage suppression as well as the power generation performance is comparatively analyzed. A prototype of the stator-damper winding DSBLDC generator is designed and developed. The experimental results show that the induced voltage of the field winding is reduced by more than 90%, while the output power is nearly close to that of the conventional DSBLDC generator. [ABSTRACT FROM AUTHOR]

Doubly salient wound field machines exhibit the advantages of robust structure and controllable flux, and hence have been utilized as generators in applications of automobiles and renewable energy. However, the inherent unbalanced phase back-electromotive force (EMF) waveform caused by the asymmetric flux path brings difficulties for precise control and smooth operation. To solve the problem caused by unbalanced back-EMF waveform in conventional doubly salient machines, this paper presents a novel doubly salient wound field machine with balanced and symmetrical back-EMF waveform as starter generator in automobile application. The robust structure and the controllable flux are inherited, while the magnetless feature makes it promising for cost-sensitive applications. The proposed machine can be operated as an assistant motor for torque boosting at start-up stage, as well as a power recycling generator for battery charging at steady state. It is revealed that the proposed wound field machine exhibits similar cost, comparable torque density, improved torque ripple, and higher efficiency than the switched reluctance machine. Finally, the proposed prototype is fabricated, and dynamic experiment is conducted to validate the feasibility for automobile starter generator application. [ABSTRACT FROM AUTHOR]

In this paper, a circulating-current-excited switched reluctance generator system with the diode rectifier is comparatively studied with a field-current-separated switched reluctance generator. By using a DC power source connected in series with the winding to provide the circulating current, a controllable excitation field is established in the proposed generator. To highlight the influence of this DC voltage source, the injected field current of the field-current-separated generator is kept the same as the circulating current of the circulating-current-excited generator. Then, both advantages and disadvantages of the generators are summarized. The circulating-current-excited switched reluctance generator system inherits both the advantages of good reliability of the separated-winding generator by using the diode rectifier and low copper loss of the integrated-winding machine by combining the AC and DC current in one set of windings. Furthermore, two more practically conventional field-current-separated generators are also compared with the proposed generator in terms of the external characteristics. These two conventional generators have different winding configurations. At last, the analysis is verified by experiments. [ABSTRACT FROM AUTHOR]

A hybrid excitation brushless dc generator (HEBLDCG) system, consisting of a main generator (MG) and an integrated exciter, is proposed and developed in this article. The excitation sources types of the stand-alone generation system and corresponding characteristics of the sources types are summarized. In the target HEBLDCG system, the integrated exciter shares a flux path with the permanent magnet machine part (PMMP), which is a part of the MG, without extracting power from the output terminal or sacrificing the efficiency of the generation system. It is the reactive power in the PMMP that leads to these aforementioned advantages. Also, the basic design flowchart of the exciter is expounded upon, and the values of some parameters are discussed. The designed exciter meets the requirements of the field power of the MG for the whole speed range and under varying load conditions. Based on the well-designed exciter, the electromagnetic performance is analyzed in terms of its open-circuit and load performance. Furthermore, the reason why the output power of the MG is not reduced by the integrated exciter is analyzed. Finally, open-circuit and load experiments for the exciter are conducted, and the proposed excitation method is found appropriate for the HEBLDCG system. [ABSTRACT FROM AUTHOR]

A doubly salient electromagnetic starter/ generator (DSESG) system based on the bidirectional converter (BDC) is proposed, in this article. The BDC is operated as an inverter in starting mode and as an active rectifier (AR) in generation mode. Compared to the conventional DSESG system, which is based on an inverter and a diode rectifier or a discrete inverter/rectifier unit (IRU), the configuration is simplified and the weight is reduced. Since the output voltage is improved by the angular position control (APC), field and phase currents are redistributed. The copper loss optimization control (CLOC) for the AR is proposed. The copper loss is analyzed based on the extreme learning machine (ELM) and the turn-off angles are selected. The copper loss is minimized and the heat is reduced. The copper loss and heat generation are also balanced in the field and phase windings to decrease the temperature of the field windings at low speed. Experimental verifications are conducted on a 9 kW DSESG prototype. The effectiveness of the proposed ELM-based CLOC is verified by simulation and experiments. A lighter and simpler DSESG system with reduced loss is presented. [ABSTRACT FROM AUTHOR]

A DC-link voltage regulation method is proposed based on capacitor energy control (CEC) for the doubly salient electro-magnetic generator (DSEG) system. Instead of tracking the DC-link voltage, the stored energy in the DC-link capacitor is set as the control target in the outer loop. A proportional component that converts the command output current into the command field current is developed between the capacitor energy loop and field current loop. The coefficient in the proportional component is investigated based on the mathematical model of the 12–8 pole DSEG, considering the load and speed variation. The dynamic response of the DSEG system is accelerated and the DC-link voltage variation is reduced with the proposed method. Furthermore, the adaptability to speed variation of the controlled is optimized. Since the DC-link capacitance is an additional parameter, the influences of capacitor degradation are investigated. The conventional voltage control and the CEC are implemented and compared on a DSEG platform. The optimized performance of the proposed method is verified by both finite element analysis (FEA) and experiments. The proposed method provides optimized dynamic performance over the entire speed range, enabling the DSEG system as a competitive option in the aircraft application. [ABSTRACT FROM AUTHOR]

A new hybrid excitation brushless dc generator (HEBLdcG) is comprised of the structure-paralleled permanent magnet machine part and flux modulation machine part (FMMP). The reactive power compensation effect of the HEBLdcG is illustrated and investigated in this paper. It is shown that the operation modes of the FMMP are influenced by both, the field current and armature current. Based on this, the three ranges in terms of the field current are divided. Three typical operation states representatively selected in the three ranges are defined as the power-balance state, compensator state, and short-circuit state, respectively. The short-circuit current can be diminished on account of the reactive power compensation effect. Furthermore, the analysis of the short-circuit characteristics shows that the short-circuit characteristic curve—short-circuit output current versus field current—is not a straight line, due to the saturation of the d-axis flux path of the FMMP. And the HEBLdcG at −8-A field current features the lowest total loss at the short-circuit state. At last, a prototype HEBLdcG is manufactured and the experiments validate the simulations. [ABSTRACT FROM AUTHOR]

This paper proposes an integrated method of three-phase ac excitation and high-frequency voltage signal injection (HFVSI) for sensorless controlled starting of brushless synchronous machines (BSM) used as starter/generator in variable frequency ac power systems of civil aircraft. Fixed 400 Hz of the three-phase ac power is adopted both for the ac excitation and HFVSI in the initial starting process to eliminate the bulky rotor position sensor for BSM. The resulting 6th sequence harmonic voltage determined by the rotating rectifier is utilized as the HFVSI into the field-winding of main generator without any extra high-frequency signal injection. The rotor position is estimated by the high-frequency response signals extracted from the armature windings of main generator. Due to the nonlinear rotating rectifier linked in the HFSI chain, a novel frequency-insensitive asynchronous demodulation strategy is proposed in this paper for rotor position estimation. Furthermore, the initial rotor position detection is calibrated by polarity decision of the induced currents of the armature windings within the establishment procedure of field current of the main generator at standstill. The effectiveness of the ac excitation and feasibility of rotor position estimation for sensorless starting control of BSM are validated by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

With the development of more electric aircraft, higher demand for electrical energy is put forward in generation systems. The constant speed drive is eliminated in variable frequency ac (VFAC) generation systems, which makes integrated starter-generator (SG) can be realized. Considering the inherent defects of wound rotor synchronous SG systems, such as the complex starting excitation methods and rotating rectifiers, this paper proposes a VFAC SG system based on hybrid excitation synchronous machines (HESMs) for aircraft applications. The key technology of HESM-based VFAC SG system is to regulate the field current in such a way that three major modes of VFAC SG system operation for aircraft applications, namely, engine starting operation, transition mode, and generating operation, can be realized effectively. The simulation model of HESM-based VFAC SG system is built and analyzed. A prototype HESM-based VFAC SG system has been designed and developed for experimental verification. The starting operation, transition mode, and generating operation of the prototype HESM-based VFAC SG system are implemented. The feasibility of HESMs to VFAC SG system for safety-critical aircraft applications has been validated. [ABSTRACT FROM AUTHOR]

This paper proposes and analyzes the design philosophies of the single-phase main exciter (ME) for an aircraft wound-rotor synchronous machine and investigates its operating characteristics in both generating and starting modes. The fundamental structure and starting–generating system are discussed. The load features of single-phase ME are summarized. The ME has the characteristics of linear current amplifier and approximately constant current source the generating mode, which can be used in the wide range of working temperature. Detailed waveforms and finite-element analysis verify that excitation current $I_{\mathrm {ef}}$ is almost irrelevant to speed but in direct proportion to frequency in the starting mode. Besides, simulated data indicate that the energy transferring efficiency between ME stator and rotor can reach about 55% by the single-phase ac excitation method. Finally, the experimental verification is carried out, and the simulated and experimental data and waveforms of single-phase ME agree well with each other. [ABSTRACT FROM AUTHOR]

In this paper, a new shaded-pole main exciter (ME) with additional short-circuited coils for aircraft three-stage starter–generator (SG) is proposed and investigated. The basic structure, winding configurations, operating principle, and start system structure of the presented shaded-pole ME are illustrated in detail. The comparative study between the original ME and the shaded-pole ME with respect to the starting mode performances is conducted by 2-D finite-element method (FEM). A prototype SG with original ME has been developed, and the experimental results are essentially consistent with the simulation results by the FEM utilized in the predictions in this paper. Simulation data and waveforms verify that the proposed shaded-pole ME is a good candidate for aircraft machines to satisfy the dual function of starter and generator. [ABSTRACT FROM AUTHOR]

In this paper, a variable-speed operating doubly salient electromagnetic generator (DSEG) for an automobile power system is proposed and investigated. Analysis and comparison between the 12/8-pole and the 18/12-pole configurations are given. The 18/12-pole DSEG is more suitable for the wide-speed range operation in terms of the capability of output power and efficiency due to the smaller reactance. The characteristic of flux regulation for the constant power operation in a wide speed range is analyzed, and the corresponding loss variation and efficiency is obtained as well. Finally, a prototype 18/12-pole DSEG has been designed. Both the simulation and the experimental results indicate that the proposed DSEG can offer a more desirable and stable power performance over a wide speed range with simple control for the automobile on-board generation application. [ABSTRACT FROM AUTHOR]

The doubly salient brushless dc generator (DS-BLDCG) is constituted by a doubly salient electromagnetic generator (DSEG) and the associated rectifier circuit. The DS-BLDCG is suitable for the automobile auxiliary power unit (APU) application due to its merits of simplicity, high robustness, low cost, and flexible control. Since no constraint is imposed to the number of phases of the onboard brushless dc generator, the polyphase DSEG can be employed. In this paper, a 3-phase 12/8-pole DSEG and a 4-phase 16/12-pole DSEG with a rectifier circuit for the APU application are proposed. The taper stator pole and broadened rotor pole structure utilized to increase maximum output power is introduced in the four-phase DSEG design. Based on the two-dimensional (2-D) finite-element method (FEM) and field-circuit coupling analysis, a comprehensive comparison is presented. The 16/12-pole DS-BLDCG with broadened rotor pole exhibits lower peak value of the phase inductance yet larger negative phase current commutation overlapping angle. The rectifier circuit of the 16/12-pole DS-BLDCG is more complex and the copper consumption of the 12/8-pole DS-BLDCG is slightly less. A prototype 12/8-pole DS-BLDCG for the APU application is designed and developed. Both the simulation and experimental results indicate that the developed DS-BLDCG is a promising option for automobile APU application. [ABSTRACT FROM PUBLISHER]

The unit machine of the traditional doubly salient electro-magnetic generator (DSEG) has a 6/4-pole structure, so it must have a large number of stator poles when used as a low speed wind turbine generator. The matching relationship between the stator pole number and the rotor pole number of a multi-poles-rotor DSEG is deduced, and a new 3N/4N-pole DSEG is proposed. The magnetostatic field distribution, excitation inductance characteristic, as well as output characteristic of the DSEG is investigated by 2-D and 3-D finite element analysis. Comparisons between the two different structures are presented in terms of power density, voltage ripple and efficiency. A low speed 24/32-pole prototype machine is developed, and the experimental results are given to verify the validity of the simulation analysis and the reasonable structure of 3N/4N-pole DSEG. [ABSTRACT FROM PUBLISHER]

This paper investigates a novel variable-speed generation system. A new integrated power circuit with voltage clamp protection and self-excitation function is presented. Conventionally, due to the large internal impedance of a generator, oscillations are produced by the resonances of the filter in armature currents which may cause unstable behavior of the generation system. In this paper, an active damping control algorithm cooperated with matrix converter (MC) instantaneous value synthesizing modulation strategy is proposed to suppress oscillations of MC input currents effectively. In addition, a closed-loop voltage control scheme with MC constant transfer ratio and hybrid excitation synchronous generator excitation current regulation is studied. At last, the feasibility of the overall system and schemes has been verified by the experimental results. [ABSTRACT FROM PUBLISHER]