• Journal of Electrical Engineering and Technology
• /
• v.1 no.2
• /
• pp.241-245
• /
• 2006

In this paper, the design and characteristics of a $\pi-shaped$ ultrasonic motor that is applicable to optical zoom operation of a lens system for mobile phones are investigated. Its design and simulation of performances are carried out by FEM (finite element method) commercial software. As a simulation result, by applying voltage with single phase, a combined vibration is produced at the surface of a stator arm. A prototype of the motor is fabricated and its outer size is $8*4*2mm^3$ including the cylindrical steel rod of 2 mm in diameter as the rotor. The motor exhibits a maximum speed of 500 rpm and a power consumption of 0.3 W when driven at 20 Vpp and 64 kHz.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2365-2372
• /
• 2011

The Cogging Torgue is non-uniform torgue in motor which causes noise and vibration to synchronous motors such as BLDC motor, and regardless of load current, is generated by the interaction between permanent magnet rotor and stator slot which is the force of tangential direction that tends to move into the position where the magnetic energy of motor system is minimal. such Cogging Torgue shall be considered in design stage since it is the main factor of motor's noise and vibration. Understanding that Cogging Torgue is generated by the interaction between relatively low stage harmonic flux density gab of permanent magnet rotor and steel slot of stator. This study proposes the method if reducing Cogging Torgue using response surface method which is a kind of design if experiment.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.10
• /
• pp.1481-1487
• /
• 2017

This paper proposes a sensorless speed control algorithm for parallel-connected dual Surface-mounted Permanent Magnet Synchronous Motors fed by a single inverter. For stable parallel operation of synchronous motors with a single inverter, each motor has to be constantly kept in the synchronization state regardless of load torque. If the master motor with the larger load is controlled, the synchronous state will be maintained. Therefore, detection of the master motor is essential. Conventionally, the master motor is determined by comparing the rotor position error from the relation between the back-EMF for torque angle and the flux position. consequently, the position sensor is deemed essential for finding the rotor position. In this paper, we proposed a method that decides the magnitude of the load from the power angle of two motors due to the load variation and selects the motor to control through the sign function for the sensorless speed control without the position sensor. The results of simulation and experiment conducted verify the efficacy of the proposed method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.187-188
• /
• 2008

An ultrasonic motor of high torque with a new configuration for application in automobiles is proposed. The newly designed stator is a two sided vibrator consisting of a toothed metal disk with a piezoelectric ceramic ring bonded on both faces of the disk which generates a flexural traveling wave along the circumference of disk. In this configuration, the displacement on the surface of stator may not be confined. It also produces a large vibrating force and amplitude because the vibrator is sandwiched by two piezoelectric plates. It is possible to increase the torque by improving the vibration characteristics. To compute the vibration mode of the motor of diameter 48 mm, the finite element method was used. A 6th mode was chosen as the operation mode with a resonance frequency of about 64.4 kHz. According to this design and measured its performance, a prototype was fabricated. The performance measurement of the prototype motor showed that its stall torque was about 1.8 Nm and efficiency was 37% at 60% of the maximum torque.

• Journal of Hydrogen and New Energy
• /
• v.23 no.5
• /
• pp.484-492
• /
• 2012

The TMS(Thermal Management System) heater in a fuel cell vehicle has been developed to prevent a decline of fuel cell durability and cold start durability. Main functions of the COD(Cathode Oxygen Depletion) heater are depletion of oxygen in a cathode as heat energy and consumption of electric power for rapid warming up of a fuel cell stack. This paper covers subjects including the design specification of a heater, heater controller for detection of overheat and reliability assessment including coolant pressure cycle test of a heater. To verify the design concept, burst pressure and deformation analysis of plastic housing were carried out. Also, temperature distribution analysis of heater surface and coolant inside of housing were carried out to verify the design concept. By designing the plastic housing instead of a steel housing, the 30% weight lightening and 50% cost reduction were attained. A module-based design of a TMS system including a heater or reducing the watt density of a heater is a problem to be solved in the near future work.

• International Journal of Automotive Technology
• /
• v.7 no.3
• /
• pp.321-327
• /
• 2006

The previous paper described the logic tuning, the vehicle manufacture and the evaluation in the HILS system for the purpose of the development of a Steer-By-Wire(SBW) system. This paper describes the content of applying to a new HILS system, the vehicle manufacture and the result of the evaluation performed in Independent-type SBW(I-SBW) system. Here, the SBW indicates the method of steering both tires by using one motor as the steering gear actuator, similar to the conventional steering system. On the other hand, the I-SBW means the method of steering both front tires independently by using dual motors as the steering gear actuator. As a result, the layout and the kinematical mechanism of the I-SBW system are quite different from those of the typical steering mechanism. Nevertheless, there is no change in the steering column motor system. In the report, we first describe the structure and control logic of the I-SBW system, and then the control effect on this system as applied for both the HILS system and a vehicle. Furthermore, our HILS system involves the actuator mechanism which realizes the reaction force of the road surface with a minimized frictional force in operation. Therefore, it is possible for us to tune the control logic via the HILS system and confirm the effect of the tuned control logic by applying it to a vehicle with the I-SBW system.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.9
• /
• pp.427-433
• /
• 2001

A linear ultrasonic motor was designed by a combination of the first longitudinal and fourth bending mode, and the motor consisted of a straight aluminum alloys bar bonded with a piezoelectric ceramic element as a driving element. That is,$L_1-B_4$ linear ultrasonic motor can be constructed by a multi-mode vibrator of longitudinal and bending modes. Linear ultrasonic motors are based on an elliptical motion on the surface elastic body, such as bar or plates. In general, the natural resonance frequency of the stator is used as a driving frequency of the motor which provides a large elliptical motion. The corresponding eigenmode of one resonance frequency can be excited twice at the same time with a Phase shift of 90 degrees in space and time. And the rotation can be reversed by changing the phase between the two signals from sin$\omega$t to cos$\omega$t. Moreover, the tangential force pushes the slider(rotor) and, therefore, determines the thrust and speed of the motor. The experimental results of fabrication motors, bimorph-tyPe motor showed more excellent than unimorph-type. The maximum speed of TBL-200, TBL-300, TBL-400, TBL -220, TBL-310 and TBL-420 motors were 0.12, 0.37, 0.39, 0.14, 0.55 and $0.60ms6{-1}$, respectively. And the efficiency were reported 1.15, 7.9, 6.6, 2.36, 10.1 and 16.5%, respectively. That time, output thrust of the motor was a strong(1~2N) and the weight of stator was a lightness(5~7g).

• Proceedings of the Korean Magnestics Society Conference
• /
• 2008.12a
• /
• pp.102.2-102.2
• /
• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.475-478
• /
• 2004

In this paper, a magnet-type automatic pipe cutting machine that binds itself to the surface of the pipe using magnetic force and executes unmanned cutting process is proposed. During pipe cutting process when the machine moves around the pipe laid vertical to the gravitational field, the gravity acting on the pipe cutting machine widely varies as the position of the machine varies. That is, with same driving force from the driving motor the cutting machine moves faster when it climbs down the surface of the pipe and moves slower when it climbs up to the top of the pipe. To maintain a constant velocity of the pipe cutting machine and improve the cutting quality, the authors adopted a conventional PID controller with a feedforward effort designed based on the encoder measurement of the driving motor. It is, however, impossible for the encoder at the motor to measure the absolute position and consequently the absolute velocity of the cutting machine in the case where the slip between the surface of the pipe and wheel of the cutting machine is not negligible. As an attempt to obtain a better estimation of the absolution angular position/velocity of the machine the authors proposes the use of the MEMS-type accelerometer which can measure static acceleration as well as dynamic acceleration. The estimated angular velocity of the cutting machine using the MEMS-type accelerometer measurement is experimentally obtained and it indicates the significant slipping of the machine during the cutting process.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.3
• /
• pp.240-248
• /
• 2017

This paper describes the development of a powertrain for a 20 kW experimental electric vehicle using a surface-mounted permanent magnet synchronous motor (SPMSM) and its application to a test vehicle. Two 10 kW SPMSMs are used in the powertrain, and two-level inverters are developed by using IGBTs to derive these motors. To control the SPMSM, a control board based on a TMS320F28335 DSP module, which has fast arithmetic function and floating point operator, is used. We develop a 100 V/40 A battery pack, which includes $32{\times}4$ LiFePO4 battery cells using commercial BMS. A commercial on-board charger with 220 V (AC) input and 100 V (DC) and 18 A output is used to charge the battery pack. The performance of the developed vehicle, such as acceleration availability, maximum speed, and maximum power, is estimated based on vehicle dynamics and verified through experiments.