Brushless DC Generator Research Articles

Wind–PV–Battery Hybrid Off-Grid System: Control Design and Real-Time Testing

The paper presents the design and implementation of decentralized control for a PV–wind–battery hybrid off-grid system with limited power electronics devices and sensors. To perform well without using any maximum power point tracking (MPPT) technique from the wind turbine (WT) based on a permanent-magnet brushless DC generator (PMBLDCG) and solar panels (PVs) and balance the power in the system, a cascade control structure strategy based on a linear active disturbance rejection controller (LADRC) is developed for the two-switch DC-DC buck-boost converter. Moreover, to ensure an uninterruptible power supply to the connected loads with a constant voltage and frequency, a cascade d-q control structure based on LADRC is developed for the interfacing single-phase inverter. Furthermore, the modeling and controller parameters design are presented. The performance under all operation conditions of the hybrid off-grid configuration and its decentralized control is validated by simulation using MATLAB/Simulink and in real-time using a small-scale hardware prototype.

Grid Sychronization of Wind Based Microgrid

Abstract: This paper presents the methods for synchronization of a wind based micro grid with main grid. The wind power is generated using the permanent magnet brushless DC generator (PMBLDCG) and the MPPT (Maximum Power Point Tracking) is executed with P&O (Perturb & Observe) approach to extract the maximum power from the wind generation. This power is fed to the AC load using a voltage source inverter (VSI) through the battery bank (BSS) at DC link. The control algorithm operates in standalone mode and grid connected mode. It can switch between islanded and grid connected modes seamlessly according to the wind conditions. In standalone mode, this wind power is fed to the load through a VSI, during low wind conditions; the battery discharges itself to fulfill the load demand. After that, the grid is connected to give power to the load during low wind conditions, and for this, control algorithm operates in grid connected mode. Therefore, the control algorithm switches from voltage control to current control mode to provide smooth synchronization and vice versa at de-synchronization. A MATLAB Simulink model is developed to simulate the system performance during wind variations and load, and during synchronization and de-synchronization.

Scheme design of brushless DC excess power generation system

Brushless motors have the advantages of no brush, low interference, long life, and low maintenance costs, which are increasingly used in aviation power systems. According to the reliability requirements of the aircraft power generation system, this paper proposes a brushless DC excess power generation system scheme, which sends the alternating current generated by the main motor of the brushless DC generator to the AC/DC converter and primary power distribution, while retaining the main motor power generation converted into DC power through the internal rectifier circuit of the motor. The generator controller is designed with double surplus output to improve the reliability of the system power supply.

Improvement of Integrated-Induction-Based Hybrid Excitation Brushless DC Generator by Employing Novel Consequent-Pole Rotor

In order to achieve both the brushless excitation and flexible regulation of output voltage, the integrated-induction-based hybrid excitation brushless dc generator (II-HEBDCG) combining the main generator part with the induced excitation part is presented in this article. Moreover, the novel consequent-pole rotor featuring the pole sequence of iron-S-iron-iron-N-iron (I-S-I-I-N-I) is proposed to enhance the flux regulation capability because each coil of the main field winding (MFW) can regulate the flux of two iron poles simultaneously, where the flux paths of permanent magnet and MFW exhibit in parallel. The selection rules of pole and slot combination are summarized theoretically, and the principle of flux regulation is revealed based on the equivalent magnetic circuit, which are confirmed by finite element analysis. Then, the influences of key parameters on the performance are discussed. Furthermore, the electromagnetic performance of the proposed II-HEBDCG with the pole sequence of I-S-I-I-N-I, including the no-load flux density distribution, no-load voltage regulation, output characteristics, loss and efficiency, are comprehensively investigated and compared with that of the II-HEBDCG with conventional pole sequence of N-iron-iron-iron. It is demonstrated that the proposed II-HEBDCG obtains not only better flux (or voltage) regulation capability but also higher output power, and hence, obtains higher efficiency than the conventional one. Finally, a prototype is built and tested to verify the analyses.

Reduction of Field-Winding-Induced Voltage in a Doubly Salient Brushless DC Generator With Stator-Damper Winding

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.

AC Loss Calculation and Analysis of Hollow Conductor for Doubly Salient Brushless DC Generator

The hollow conductor has attracted attention in variable reluctance machines (VRMs) working in harsh environment due to its good heat dissipation performance. The abundant harmonic content of the magnetic field in the slot of VRM and the complex structure of the hollow conductor make ac loss characteristics of the hollow conductor complex. Accurate and fast ac loss calculation is necessary to optimize the efficiency of VRM and provide the basis for thermal design. The doubly salient brushless dc generator (DSBLDCG), as the VRM, is analyzed in this article. First, the ac loss of the hollow conductor under a uniform alternating magnetic field is modeled numerically. The loss characteristics of hollow conductor in DSBLDCG are obtained by combining the analytical model and the simplified finite element (FE) model. Second, the refined FE model of DSBLDCG with the hollow conductor winding is established to verify the proposed method, and the influence of different structural parameters and operating conditions on the ac loss of the hollow conductor is also analyzed. Finally, the ac loss test experiment is designed for experimental verification.

Integrated-Induction-Based Hybrid Excitation Brushless DC Generator With Consequent-Pole Rotor

This article proposes a novel hybrid excitation brushless dc generator (HEBDCG), in which the main generator part and the induced excitation part share one set of the stator/rotor core (namely integrated-induction-based HEBDCG, i.e., II-HEBDCG). Hence the auxiliary magnetic path and additional airgap do not exist and then high space utilization are achieved. Moreover, the consequent-pole rotor featuring permanent magnet (PM) pole-iron pole-iron pole-iron pole (N-I-I-I) is adopted to utilize the high permeability of iron poles, which is favorable to the flux and voltage regulation. The selection rules of pole and slot combination are given by comprehensively considering the unbalance magnetic force and the relationship of the electrical coupling between the main generator part and the induction excitation part. Then, the principle of flux regulation is revealed by equivalent magnetic circuit, and validated by finite element (FE) analysis. In addition, the influences of key factors including the distribution of induction winding on the performance are discussed, and both the no-load regulation, load characteristics and armature reaction are investigated. Furthermore, the proposed II-HEBDCG is compared to the conventional three-stage brushless dc generator (TSBDCG). It is shown that the proposed II-HEBDCG achieves steady excitation current and flexible regulation of output voltage, and obtains both the higher output power and efficiency than the TSBDCG. Finally, a prototype is manufactured and measured to validate these analyses.

Modeling, Controller Design and Simulation Groundwork on Multirotor Unmanned Aerial Vehicle Hybrid Power Unit

This paper presents the results of modeling, control system design and simulation verification of a hybrid-electric drive topology suitable for power flow control within unmanned aerial vehicles (UAVs). The hybrid power system is based on the internal combustion engine (ICE) driving a brushless DC (BLDC) generator supplying the common DC bus used for power distribution within the aircraft. The overall control system features proportional-integral-derivative (PID) feedback control of the ICE rotational speed using a Luenberger estimator for engine-generator set rotational speed estimation. The BLDC generator active rectifier voltage and current are controlled by proportional-integral (PI) feedback controllers, augmented by estimator-based feed-forward load compensators. The overall control system design has been based on damping optimum criterion, which yields straightforward analytical expressions for controller and estimator parameters. The robustness to key process parameters variations is investigated by means of root-locus methodology, and the effectiveness of the proposed hybrid power unit control system is verified by means of comprehensive computer simulations.

Sliding Mode Control of Hybrid Renewable Energy System

This paperpresents an ANFIS based adaptive sliding mode control (ASMC) of a standalone single phase microgrid system. The proposed microgrid system integrates a micro-hydro turbine driven single-phase two winding self-excited induction generator (SEIG) with a wind driven permanent magnet brushless DC (PMBLDC) generator, solar photo-voltaic (PV) array and a battery energy storage system (BESS). These renewable energy sources are integrated using a single-phase voltage source converter (VSC). The ASMC based control algorithm is used to estimate the reference source current which controls the single-phase VSC and regulates the voltage and frequency of the microgrid in addition to harmonics current mitigation. The adaptive sliding mode control with ANFIS is used to maintain the energy balance among wind, micro-hydro, solar PV power and BESS, which controls the frequency of standalone microgrid. Simulation results from MATLAB/SIMULINK of the proposed microgrid shows that the grid voltage and frequency are maintained constant while the system is following various changes in dynamic state such as sudden change in wind speed, changes in solar insolation level and changes in loads.

Voltage Regulation of Hydro Standalone 1-Φ Micro Grid using Fuzzy Logic Based Adaptive Sliding Mode Control Algorithm

This paper presents an adaptive sliding mode control (ASMC) of an improved power quality standalone single phase microgrid system. The proposed microgrid system integrates a governor-less micro-hydro turbine driven single- phase two winding self-excited induction generator (SEIG) with a wind driven permanent magnet brushless DC (PMBLDC) generator, solar photo-voltaic (PV) array and a battery energy storage system (BESS). These renewable energy sources are integrated using only one single-phase voltage source converter (VSC). The ASMC based control algorithm is used to estimate the reference source current which controls the single-phase VSC and regulates the voltage and frequency of the microgrid in addition to harmonics current mitigation. The proposed ASMC estimates the reference real and reactive powers of the system, which is adaptive to the fluctuating loads. The sliding mode control is used to estimate the reference real power of the system to maintain the energy balance among wind, micro-hydro, solar PV power and BESS, which controls the frequency of standalone microgrid. The proposed microgrid is implemented in real time using a DSP (Digital Signal Processor) controller. Test results of proposed microgrid shows that the grid voltage and frequency are maintained constant while the system is following a sudden change in loads and under intermittent penetration of wind and solar energy sources.

Adaptive Neural Fuzzy Inference System Based Adaptive Sliding Mode Control of a Standalone Single-Phase Microgrid

This paperpresents an ANFIS based adaptive sliding mode control (ASMC) of a standalone single phase microgrid system. The proposed microgrid system integrates a micro-hydro turbine driven single-phase two winding self-excited induction generator (SEIG) with a wind driven permanent magnet brushless DC (PMBLDC) generator, solar photo-voltaic (PV) array and a battery energy storage system (BESS). These renewable energy sources are integrated using a single-phase voltage source converter (VSC). The ASMC based control algorithm is used to estimate the reference source current which controls the single-phase VSC and regulates the voltage and frequency of the microgrid in addition to harmonics current mitigation. The adaptive sliding mode control with ANFIS is used to maintain the energy balance among wind, micro-hydro, solar PV power and BESS, which controls the frequency of standalone microgrid. Simulation results from MATLAB/SIMULINK of the proposed microgrid shows that the grid voltage and frequency are maintained constant while the system is following various changes in dynamic state such as sudden change in wind speed, changes in solar insolation level and changes in loads

Analysis of a Hybrid Excitation Brushless DC Generator With an Integrated Shared-Flux-Path Exciter

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.

Robust Control Strategies for SyRG-PV and Wind-Based Islanded Microgrid

The nonlinearity in the consumption does not maintain steady voltage or frequency; therefore, in this article, a circular limited cycle oscillator frequency locked loop with prefilter (CLO-FLL-WPF) based control for voltage source converter control is used to achieve voltage and frequency regulation in an islanded microgrid (MG). This control is implemented to compensate local load reactive power, harmonic currents, and load unbalance. Besides, the active power of local loads is shared among the multiple energy sources. The CLO-FLL-WPF control technique performance is validated experimentally and through simulations by comparing it with the existing control algorithm in a MG. This MG is a combination of the solar photovoltaic array, pico-hydro turbine-driven synchronous reluctance generator, permanent magnet brushless dc generator based wind energy conversion, and battery storage. In traditional battery control, a proportional-integral control approach is used, which can cause a stability problem. Thereby, in this article, the bidirectional dc–dc converter control method is used, which provides improved stability and makes the controller design straightforward. Test results validate the effectiveness of the control algorithm under different dynamic and steady-state conditions.

Phase Displacement Characteristics of a Parallel Hybrid Excitation Brushless DC Generator

The article presents theoretical analyses and comprehensive simulations on the phase displacement characteristics of a parallel hybrid excitation brushless DC generator (HEBLDCG). The HEBLDCG, which consists of the permanent magnet (PM) machine part and flux modulation machine part, operates at the unity displacement factor due to the diode rectifier. The PM flux and wound field flux are coupled at load because the armature windings of two parts are in series connection. By the analysis of the armature reaction, the phase displacement between phase voltage and phase current of each part is revealed. It is further deduced that the phase relationship between two parts is determined by the saliency ratio and the “displacement characteristic current” which is defined as the ratio of the fundamental electromotive force at no-load and the d -axis reactance. Based on this, the mode division method from the view of power and loss balance is proposed. These comprehensive operation modes, indicated by the internal power flow, facilitate a constant output voltage and power of the HEBLDCG under variable loads and operation speeds. Finally, the experiments verify the analyses at the constant output voltage operation.

Thermal Analysis and Management for Doubly Salient Brushless DC Generator With Flat Wire Winding

The preformed flat wire winding is widely applied in doubly salient brushless DC generator with a rectangular slot structure due to the high slot filling factor and processing efficiency. The windings are commonly identified as the hottest component. The slot leakage is serious in the doubly salient structure machine, which increases the AC copper loss and thermal load of flat wire winding. Hence, predicting and lowering windings temperature are crucial tasks in the design of a doubly salient brushless DC generator with a flat wire winding. This article proposes the thermal modeling method of flat wire winding, where uneven AC copper loss distribution and thermal resistance between stator and winding are considered. Besides, the thermal model is simplified by canceling the local coordinate system. The characteristics of the temperature distribution of flat conductor winding under water-cooled and fan-cooled conditions are analyzed. Since the thermal resistance between stator and winding prevents the transfer of heat from the winding to the stator, the fan-cooled method is a better choice for the flat conductor winding. Finally, the thermal resistance measurement experiment is the design, and the fan-cooled brushless DC machine with flat conductor winding is developed. The analysis is verified through experiment.

Comprehensive Controller Implementation for Wind-PV-Diesel Based Standalone Microgrid

In this paper, a comprehensive controller of a standalone microgrid is implemented, which has three dispersed generation units based on a wind, solar photovoltaic (PV) array, and a diesel generator (DG). The power ratio variable step perturb and observe method is applied to achieve maximum power point tracking of a solar PV array and a variable speed wind turbine coupled a permanent magnet brushless dc generator without rotor/wind speed sensors. Moreover, to ensure perfect synchronization of a DG to the point of common coupling (PCC), a control algorithm is developed, which is based on in-phase and quadrature units. An active power control based on proportional–integral controller with anti-windup, is used for voltage and frequency regulation. The LCL filter based on virtual resistor, is used for power quality improvement at PCC. Simulation and test results are presented for the validation of the proposed system using a prototype of 2 kW in the laboratory.

Electromagnetic‐based maximum output power control in new two‐layer BLDC generator using optimal control of turn‐on and turn‐off angles in variable speed applications

In this study, by using the electromagnetic field analysis, the design of brushless DC generator with a novel construction and controller, appropriate for variable speed applications, is proposed. In the proposed machine, unlike the conventional structure, an assisted DC field coil is employed instead of permanent magnet excitation to provide a regulated voltage. Results of the electromagnetic field analysis show that including the DC field coil increases the controllability of the flux in different machine parts which provide a regulated terminal voltage in a wide speed range appropriate for variable speed applications. Moreover, the maximum power point tracking is achieved by controlling the DC field current along with producing optimal turn-on and turn-off angles for stator winding using the electromagnetic analysis based on optimal finite element analysis. Also, an appropriate controller is designed to control the DC field coil current. To verify the actual performance of the proposed configuration, a 1.5 Kw machine is manufactured and tested followed by the discussion on results. The obtained experimental results are in good agreement with the results of the electromagnetic analysis which confirm the maximum power trackability and robust output voltage regulation of the proposed conversion system under different shaft speeds and load conditions.

Development and Analysis of a New Hybrid Excitation Brushless DC Generator With Flux Modulation Effect

A new hybrid excitation brushless dc generator (HEBLDCG) consisting of structure-parallel permanent magnet machine part and flux modulation machine part is proposed in this paper. Based on the flux modulation effect, the permanent magnet machine and flux modulation machine parts, which have different operating principles, can be combined. In addition, the proposed HEBLDCG features a lower short-circuit current by regulating field current, which increases reliability. The operating modes of flux modulation machine part are fully analyzed under different conditions. Changes in the phase shift factor of the permanent magnet machine part caused by the operating modes of the flux modulation machine part are investigated. Further, the proposed HEBLDCG features constant voltage output at a wide range of speeds. Finally, a prototype HEBLDCG is designed and manufactured. The experimental data agree with the simulated data. Loss breakdown is analyzed and efficiency is measured. An HEBLDCG with a reliable diode rectifier is promising for application in on-board dc power generation systems.

Thermal Deformation Analysis of Water Cooling Doubly Salient Brushless DC Generator With Stator Field Winding

Thermal deformation changes the length of a variable reluctance machine's air gap; this change has a significant effect on the machine's power density and efficiency. The variable reluctance machine usually has a small air gap, which may cause scrapping failure (due to thermal deformation). Therefore, it is necessary to study the influence of thermal deformation on air gap length in order to avoid scrapping failure and to choose an optimal air gap length. The doubly salient brushless dc (DSBLDC) generator is a variable reluctance machine with stator field winding. Water cooling is the usual method for cooling a DSBLDC generator (as all excitation sources are mounted on the stator). In this paper, a water-cooling DSBLDC generator is employed to analyze thermal deformation. First, the configuration of the DSBLDC generator is introduced and the thermal distribution characteristics of the water-cooling DSBLDC generator are given. Second, the DSBLDC generator is separated into a yoke and pole in order to investigate its thermal deformation. A theoretical calculation model and a three-dimensional finite-element model are then proposed to analyze the thermal deformation. The influence of thermal deformation on the stator, rotor, and air gap length is further analyzed under different temperature distribution conditions. Finally, thermal deformation's influence on output performance is discussed and the calculation and analysis of thermal deformation are verified through experimental results.

Analysis of Reactive Power Compensation Effect of a New Hybrid Excitation Brushless DC Generator

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.