In-Gun Kim

Robust Speed Sensorless Control to Estimated Error for PMa-SynRM

Recently, the permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) that can replace an induction motor has been studying because of the needs of the high efficiency motor development for the minimum energy performance standard (MEPS). PMa-SynRM requires the speed and position information of the rotor to control motor correctly. However, a sensor for the rotor information has many problems such as mounting space shortage and additional system cost. Therefore, in this paper, the speed-sensorless control based on model reference adaptive system (MRAS) is introduced to eliminate the sensor. The proposed algorithm is verified by the simulation.

Study on the High Efficiency Design of IE4 Synchronous Reluctance Motor Replacing IE3 Induction Motor

In accordance with global energy conservation policies such as MEPS(Minimum Energy Performance Standard), electric motor industry is moving to super-high-efficiency machines and research to develop IE4 (International Energy Efficiency Class4) motors has been launched. In this situation, SynRM (Synchronous Reluctance Motor) has been attracting attention in place of induction motor which hardly provides super premium efficiency. As a result, much research on SynRM is being performed at home and abroad. Also, some products have already been appearing in the market. Compared to induction motor, SynRM has better efficiency per unit area and wider operating range. Although the utilization of control system in synchronous motor results in higher prices, we still need to concentrate on developments of SynRM so as to comply with the new policies. This study demonstrated the electromagnetic design methods of super-premium SynRM while maintaining the frame of existing IE3 induction motor for blower . We documented the design procedures for generating high saliency which is the most essential and mechanical stress analysis is also treated. In conclusion, we proved the validity of our design by manufacturing and testing our SynRM models.

Design of Permanent Magnet-Assisted Synchronous Reluctance Motor for Maximized Back-EMF and Torque Ripple Reduction

This paper proposes the optimization of the shape and size of a ferrite magnet and the arrangements necessary to reduce torque ripple and maximize back electromotive force (B-EMF) in a permanent-magnet-assisted synchronous reluctance motor. First, four different models of general magnet arrangements were selected, and analysis using the finite-element method was performed under open circuit and load operations for each of the four models. Next, the relationship between the cogging torque and the torque ripple was analyzed, considering the segment saturation phenomenon. Then, based on the initial model, the design was optimized for maximum B-EMF and minimum torque ripple, and the total harmonic distortion was measured. Finally, the validity and superiority of the optimized design were confirmed by manufacturing a prototype motor and performing the experiment.

High-Speed BLDC Motor Design for Suction Fan and Impact on the Loss caused by Core Welding

This paper deals with the effects of welding, which is done to fix the stator stack, on a motor in case of fabricating a prototype motor that is manufactured in a small quantity. In the case of a small motor, the stator is designed and fabricated with the segmented core as a way to raise the fill factor of winding wire to the utmost within a limited size. In case of fabrication by welding both inside and outside of the stator in order to fix the segmented-core stator, the effects of stack are ignored, and the eddy current loss occurs. This paper performed the no-load test on an IPM-type BLDC motor for driving the suction fan of a vacuum cleaner, which was manufactured by using a segmented-core stator. As a result of the test, it was found that input power more than expected was supplied. To analyze the effects of welding by using the finite element analysis method and verify them experimentally, a stator was re-manufactured by bonding, and input power supplied during the no-load test was compared.

A Study on the Stable Sensorless Control of BLDC Motor Inside Auxiliary Air Compressor

Pantograph must be correctly attached to catenary to continuously supply stable power to railway vehicle, and the device used here is Auxiliary Air Compressor (ACM). The existing ACM used the DC motor that included commutator and brush. Since maintenance and repair by mechanical friction are essential for the DC motor, BLDC motor studies have been conducted to improve this. A three-phase BLDC motor does 120° two-phase commutation through hall sensors in general. However, since hall sensor is vulnerable to heat and can run only when all three sensors work normally, sensorless control method has been studied to solve this. Using back EMF Zero Crossing Point (ZCP) detection method, this paper will introduce a stable switching sensing method that has a noncommutation area in a low speed zone.

A Study on the Transformer Design considering the Inrush Current Reduction in the Arc Welding Machine

The transformer used in an inverter type arc welding machine is designed to use high frequency in order to reduce its size and cost. Also, selecting core materials that fit frequency is important because core loss increases in a high frequency band. An inrush current can occur in the primary coil of transformer during arc welding and this inrush current can cause IGBT, the switching element, to burn out. The transformer design was carried out in A P method and amorphous core was used to reduce the size of transformer. In addition, sheet coil was used for primary winding and secondary winding coil considering the skin effect. This paper designed the transformer core with an air gap to prevent IGBT burnout due to the inrush current during welding and proposed the optimum air gap length.

A study on arc detection using RSSI (Received Signal Strength Indication)

With a view to detecting the series arcs in AFCI and AFDD used to prevent electrical fires, this paper explores a method of processing the low-frequency signals of electric currents, a method of detecting the arc signals using FM IF systems RSSI from certain frequency band signals in high-frequency noise signals arising when arcs occur, and an algorithm for processing the arc signals.

Reduction of core loss in the distributed winding IPMSM for ISG application

In this paper, Belt-Driven ISG was designed with IPMSM. It is important to stably satisfy wide operating range of ISG. Motoring mode at low speed is very short. ISG mainly operates as the generator at high speed, so that efficiency of generator operation is important. In the case of distributed winding motor, the harmonic eddy current losses in stator teeth are the major component under flux weakening at high speed. This paper proposed to reduce the core loss in stator teeth.

A Study on the Control to Compensate Position Sensor Error of the BLDC Motor in an Auxiliary Air Compressor

Auxiliary air compressor(ACM) applied to railroad cars is a device which controls amount of compressed air in order that pantographs can be mounted correctly on the roof of an electric train. Existing ACMs consist of dc motors and brushes wear out due to friction with a commutator. Therefore, continuous maintenance is required. However, three phase BLDC motors have higher power density compared to dc motors and the machine maintenance is not needed because electric commutation is possible. The three phase generally uses hall sensors to get position information and this enables the accurate control. This paper suggests an algorithm that compensates the errors occurred when the hall sensors have a breakdown for stable operation.Auxiliary air compressor(ACM) applied to railroad cars is a device which controls amount of compressed air in order that pantographs can be mounted correctly on the roof of an electric train. Existing ACMs consist of dc motors and brushes wear out due to friction with a commutator. Therefore, continuous maintenance is required. However, three phase BLDC motors have higher power density compared to dc motors and the machine maintenance is not needed because electric commutation is possible. The three phase generally uses hall sensors to get position information and this enables the accurate control. This paper suggests an algorithm that compensates the errors occurred when the hall sensors have a breakdown for stable operation.

A study on the torque ripple improvement of a BLDC motor via skewed magnet

This paper proposes a means to reduce torque ripple in a 2 poles, 30 (W) small size BLDC motor in radial blower. The BLDC motor have six times torque ripple interval per one period. This problem is the cause of noise and vibration that leads to the degradation of the output torque. For example, First, cogging torque is generated due to the reluctance difference of the teeth of the stator core for rotate time. It is the cause of noise and vibration that leads to the degradation of the performance. So, a plastic molding was used in order to reduce the cogging torque. The molding made the constant magnetic path between the stator and the permanent magnet thereby, reducing the cogging torque. Second, the torque ripple is generated due to a harmonic components of the magnetomotive force at the air gap difference. So a skewed permanent magnet was used in order to reduce the torque ripple. The validity of the thesis was proven via 2D, 3D FEA.