• Journal of Magnetics
• /
• v.20 no.2
• /
• pp.176-185
• /
• 2015

We present the design optimization of the magnetic pole and slot design options that minimize the cogging torque of permanent-magnet (PM) brushless generators for small wind turbine generators. Most small wind-turbines use direct-driven PM generators which have the characteristics of low speed and high efficiency. Small wind-turbines are usually self-starting and require very simple controls. The cogging torque is an inherent characteristic of PM generators, and is mainly caused by the generator's geometry. The inherent the cogging torque can cause problems during turbine start-up and cut-in in order to start softly and to run a power generator even when there is little wind power during turbine start-up. Thus, to improve the operation of small turbines, it is important to minimize the cogging torque. To determine the effects of the cogging torque reductions, we adjust the slot opening width, slot skewing, mounting method of magnets, magnet shape, and the opening and combinations of different numbers of slots per pole. Of these different methods, we combine the methods and optimized the design variables for the most significant design options affecting the cogging torque. Finally, we apply to the target design model and compare FEA simulation and measured results to validate the design optimization.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.39 no.1
• /
• pp.36-48
• /
• 1990

A new control method for robust position control of brushless dc motor is presented. The model of brushless dc motor is approximately linearized by field-orentation method, and it is shown that augmented state variable feedback can be applied to this system. In addition, robustness is obtained without any change of overall system response. Load disturbance is detected by 0-observer of unknown and inaccessible input, and is compensated by feedforward which has fast response. Overall system is controlled by using the MC68000 microprocessor, and the performance of the proposed control algorithm is verified by the results of simulation and experiment.

• Journal of Power Electronics
• /
• v.16 no.1
• /
• pp.259-267
• /
• 2016

This paper presents a stand-alone variable speed constant frequency (VSCF) ship shaft generator system based on a brushless doubly-fed machine (BDFM). In this system, the output voltage amplitude and frequency of the BDFM are kept constant under a variable rotor speed and load by utilizing a well-designed current vector controller to regulate the control winding (CW) current. The control scheme is proposed, and the hardware design for the control system is developed. The proposed generator system is tested on a 325 TEU container vessel, and the test results show the good dynamic performance of the CW current vector controller and the whole control system. A harmonic analysis of the output voltage and a fuel consumption analysis of the generator system are also implemented. Finally, the total efficiency of the generator system is presented under different rotor speeds and load conditions.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.2
• /
• pp.523-531
• /
• 2014

Brushless Dual-Mechanical-Port Electrical Machine (BLDMPEM) is a new type of motor designed for Hybrid Electric Vehicle (HEV), which contains two mechanical ports and two electric ports. Compared with Dual-Mechanical-Port Electrical Machine (DMPEM), the brushless structure brings higher reliability and easier maintenance. In this paper, the model of BLDMPEM is discussed. In Chapter 2, the energy flow and mathematical model of BLDMPEM are analyzed. Then a novel three-phase half-bridge controlled rectifier topology and its control strategy for cruising mode of HEV based on BLDMPEM are proposed in Chapter 3. Compared with the Field Oriented Control (FOC) strategy of BLDMPEM, the proposed method does not require accurate motor parameters, and it is much simpler and easier to be implemented. At last, simulation and experiment results show the feasibility and validity of the proposed strategy.

• Journal of Power Electronics
• /
• v.17 no.4
• /
• pp.1027-1036
• /
• 2017

The brushless doubly-fed induction generator (BDFIG) is a new type of dual stator winding induction generator. In such a generator, both the power winding (PW) and the control winding (CW) are housed in the stator. This paper presents the performance characteristics of a stand-alone BDFIG operation system. A new T-type steady-state model of a BDFIG is proposed. This model is more suitable for the performance analysis of stand-alone BDFIGs than the conventional Π-type steady-state model and the simplified inner core steady-state model. The characteristics of the power flow and CW current are analyzed by detailed mathematical derivations on the basis of the proposed T-type steady-state model. The analysis results are verified by experiments, which are carried out on a prototype BDFIG. The results of the performance analysis contribute to simplifying the control circuit, improving the control performance, and selecting an appropriate BDFIG for actual industrial applications.

• Journal of Power Electronics
• /
• v.19 no.5
• /
• pp.1203-1215
• /
• 2019

Sensorless brushless DC (BLDC) motor drive systems are often subjected to inaccurate commutation signals and can produce high current peaks and conduction consumption. To achieve accurate commutation, a fast commutation shift regulation method for sensorless BLDC motor drive systems considering the influence of the inductance freewheeling process is presented to compensate inaccurate commutation signals. The regulation method is effective in both steady speed and variable speed operations. In the proposed method, the commutation error is gained from the line-voltage difference integral in a 60 electrical-degree conduction period and the outgoing phase current before commutation. In addition, the detection precision of the commutation error is improved due to the consideration of the freewheeling period. The commutation error is directly obtained, which avoids successive optimization and accelerates the convergence rate of the proposed method. Moreover, the commutation error features a positive or negative sign, which can be utilized as an indicator of advanced or delayed commutation. Finally, experiments are conducted to validate the effectiveness and feasibility of the proposed method. The results obtained show that the proposed method can accurately regulate commutation signals.

• Journal of IKEEE
• /
• v.23 no.1
• /
• pp.9-13
• /
• 2019

This paper presents an optimal design of a brushless DC motor considering an advanced $165^{\circ}$ 12 step control for a cost reduction. The advanced 12 step control that extends the conduction angle $150^{\circ}$ can improve the output of the motor. The optimal design considering the improved output power of the motor is proposed by reducing the volume of rotor, stator and permanent magnet using response surface method. The proposed design satisfied the performance requirements and efficiency improvement of the conventional motor and reduced the volume about 3.5%. The feasibility of the optimal design is proved by the electromagnetic field analysis using the finite element method.

• Proceedings of the KIEE Conference
• /
• 1975.08a
• /
• pp.57-60
• /
• 1975

• Journal of Electrical Engineering and Technology
• /
• v.1 no.2
• /
• pp.185-191
• /
• 2006

In this paper, a novel stator hybrid excited doubly salient permanent magnet (SHEDS-PM) brushless machine with a special magnetic bridge is proposed for the first time. The originality of this machine is purposely to add a magnetic bridge in shunt with each PM pole, which not only maintains the stator lamination in its entireness, but also amplifies the effect of DC field flux on PM flux. An equivalent magnetic circuit is presented to clarify the novelty. Based on the 2-D finite element analysis, the static characteristics of the SHEDS-PM machine, namely phase flux linkage, back-EMF, cogging torque, winding inductance and static torque are deduced. The corresponding results on a prototype machine illustrate that the proposed machine is promising for application to electric vehicles.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.589-591
• /
• 2002

This paper deals characteristic analysis of brushless motor considering drive type. It is to divide operation with 120$^{\circ}$ and 180$^{\circ}$ conduction and to predict the current waveform and the instantaneous torque of each type using analysis method. The results of the simulation are compared the experiment.