• Proceedings of the KIEE Conference
• /
• 2004.10a
• /
• pp.64-66
• /
• 2004

Several techniques have been adopted in motor design of interior permanent magnet (IPM) type brushless DC (BLDC) motor to minimize cogging torque. IPM type motor has better ability in the centralization of flux than surface-mounted permanent magnet (SPM) type BLDC motor. So, the structure of IPM type BLDC motor has high saliency ratios that produce additional torque. However, this structure has a significant cogging torque that generates both vibration and noise. This paper describes new technique of the flux barriers design for reduction of cogging torque of IPM type BLDC motor. To reduce the cogging torque, flux barriers are applied in the rotor. Changing the number of barrier, the cogging torque is analyzed by finite clement method(FEM).

• Journal of Power Electronics
• /
• v.12 no.1
• /
• pp.58-66
• /
• 2012

SRMs(Switched Reluctance Motors) are much interested in high speed applications due to the mechanical robustness, simple structure and high efficiency. In spite of many advantages of SRMs, a higher torque ripple discourages the adoption of SRMs in a high speed application. This paper presents a simple negative torque of tail current compensation scheme using a modified TSF(Torque Sharing Function) for the high speed SRMs. Because of the short commutation in the high speed region, the negative torque from the tail current makes the high torque ripple. In order to reduce and compensate the negative torque from tail current, the proposed control scheme produces an additional compensating torque with a reference torque in the active phase winding. And the compensating value is dependent on the tail current of the inactive phase winding. Furthermore, the switching signals of the outgoing phase are fully turned off to restrict the extended tail current, and the torque error of the outgoing phase is compensated by the incoming phase. The proposed modified TSF control scheme is verified by the computer simulations with 30,000[rpm] high speed 4/2 SRM. The simulation and experimental results show the effectiveness of the proposed control scheme.

• Journal of Power Electronics
• /
• v.4 no.1
• /
• pp.1-11
• /
• 2004

A stable adaptive sensorless speed controller for three-level inverter fed induction motor direct torque control (DTC) system using the radial-basis function network (RBFN) is presented in this paper. Torque ripple in the DTC system for high power induction motor could be drastically reduced with the foregoing researches of switching voltage selection and torque ripple reduction algorithms. However, speed control performance is still influenced by the inherent uncertainty of the system such as parametric uncertainty, external load disturbances and unmodeled dynamics, and its exact mathematical model is much difficult to be obtained due to their strong nonlinearity. In this paper, the inherent uncertainty is approximated on-line by the RBFN, and an additional robust control term is introduced to compensate for the reconstruction error of the RBFN instead of the rich number of rules and additional updated parameters. Control law for stabilizing the system and adaptive laws for updating both of weights in the RBFN and a bounding constant are established so that the whole closed-loop system is stable in the sense of Lyapunov, and the stability proof of the whole control system is presented. Computer simulations as well as experimental results are presented to show the validity and effectiveness of the proposed system.

• Journal of Aerospace System Engineering
• /
• v.1 no.3
• /
• pp.7-12
• /
• 2007

As a main part of an utility helicopter, the APU(Auxiliary Power Unit) has a solenoid valve system operated with a torque motor, which controls the flow rate in the fuel supply system. In this paper, we solved the Maxwell potential equations to analyze the electromagnetic force in the torque motor, and some additional analytic methods are used to compute the quantity of torque produced by the torque motor for the given circuit current. For the convenience, small displacement is assumed, and only magneto-static problem is considered for the two-dimensional cross section. The result will be compared with the three-dimensional analysis that will be studied in the near future.

• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.158-160
• /
• 2006

The structure of interior permanent magnet type brushless DC motor (IPM type BLDC motor) has high saliency ratios that produce additional reluctance torque. But this structure has a significant cogging torque that may cause acoustic noise and vibration. In this paper describes an optimization of flux barrier in order to reduce cogging torque and torque ripple in IPM type BLDC motor using the Taguchi methods. The optimal design consider- ed noises such as manufacturing tolerances of permanent magnet size. So, optimal design ensures that torque performance is insensitive to noise.

• Journal of Magnetics
• /
• v.19 no.4
• /
• pp.411-417
• /
• 2014

This paper presents the shape optimization of a permanent magnet synchronous motor to reduce the torque ripple and iron loss. Specifically, the harmonics of the electromotive force and cogging torque are decreased by adjusting the permanent magnet arrangement and non-uniform air gap length. In addition, an additional flux path along the q-axis is proposed with a unique rotor shape to increase the q-axis inductance and reluctance torque. The improvement in the performance of the proposed model is verified with simulated and experimental results.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.262-262
• /
• 2000

This paper presents a new torque sharing function method that extends the definition region of the conventional TSF to both the positive and negative torque production regions. By using this definition, all kinds of the control inputs that consider switching on/off angle control as well as the current profiling can be described. A parametrized representation of the current profiles is proposed by using a series of B-spline functions, which reduces memory requirement and enables additional controllers. Optimal determination of the TSFs are also investigated for various control objectives. Moreover, the comparison study of each objective is presented. Since this method generalizes all of the possible control input, the current and torque profiles obtained from the optimization are the most suitable control input that satisfy the objectives.

• Proceedings of the KIPE Conference
• /
• 2011.11a
• /
• pp.315-316
• /
• 2011

This paper presents speed control scheme of the PMSM which has torque compensator to reduce the speed error and ripple. The proposed speed controller is based on the conventional PI control scheme. But the additional torque compensator which is different to the conventional differential controller produces a compensation torque to suppress speed ripple. In order to determine the proper compensation, the activation function which has discrete value is used in the proposed control scheme. With the proposed activation function, the compensation torque acts to suppress the speed error increasing. The proposed speed control scheme is verified by the computer simulation and experiments of 400[W] PMSM. In the simulation and experiments, the proposed control scheme has better control performance compare than the conventional PI and PID control schemes.

• Journal of Power Electronics
• /
• v.9 no.3
• /
• pp.438-446
• /
• 2009

The performance of direct torque controlled (DTC) interior permanent magnet (IPM) machines is poor at low speeds due to a few reasons, namely limited accuracy of stator voltage acquisition and the presence of offset and drift components in the acquired signals. Due to factors such as forward voltage drop across switching devices in the three phase inverter and dead-time of the devices, the voltage across the machine terminals differ from the reference voltage vector used to estimate stator flux and electromagnetic torque. This can lead to instability of the IPM drive during low speed operation. Compensation schemes for forward voltage drops and dead-time are proposed and implemented in real-time control, resulting in improved performance of the space vector modulated DTC IPM drive, especially at low speeds. No additional hardware is required for these compensators.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.319-322
• /
• 1997

In vector control technique, stator currents of an induction motor are transformed to equivalent d-q currents in reference frame consist of d and q axis, each of which is coincide with flux and torque direction respectively. In this paper, the new algorithm is suggested where the stator current through an induction motor torque is monitored by using a vector control method where an additional equipment is not need. The G-programming is used to apply the suggested algorithm in the experiment and this is applied to an actual system to monitor the torque value of an induction motor on real time. To solve the vibration trouble of estimated torque caused from an unbalanced real rotating speed of an induction motor and measured rotating speed by suggesting the reconstructed in a method based on measurement current signal. This produced system testifies an accuracy of an induction motor through the experiment by comparing the reference value of the control method.