하정익 교수

This paper presents a new sensorless control scheme of a surface-mounted permanent-magnet (SMPM) motor using high-frequency voltage signal injection method based on the high-frequency impedance difference. In the SMPM motor, due to the flux of the permanent magnet, the stator core around the q-axis winding is saturated. This makes the magnetic saliency in the motor. This magnetic saliency has the information about the rotor position. The high-frequency voltage signal is injected into the motor i

This paper presents the analysis of a surface-mounted permanent-magnet (SMPM) machine for the sensorless control scheme based on the high-frequency fluctuating voltage signal injection method. A simplified high-frequency model of an SMPM machine in the estimated rotor reference frame is developed and a sensorless rotor position and speed estimation algorithm is described. To support this, the high-frequency impedances of an SMPM machine are analyzed by finite-element analysis (FEA) and compared

This paper describes a new scheme to find the rotor flux angle from stator voltages and currents by injecting a high-frequency signal. The signal is not a rotating one but a fluctuating one at a reference frame rotating synchronously to the fundamental stator frequency. When the estimated rotor flux angle coincides with the actual angle, the proposed method makes virtually no ripple torque, no vibration and less audible noise caused by the injected signal. The difference of impedances between th

This paper describes a new scheme to find the rotor flux angle from stator voltages and currents by injecting high-frequency signal. The signal is not a rotating one, but a fluctuating one at a synchronous rotating reference frame with the fundamental stator frequency. When the estimated rotor flux angle coincides with the actual angle, the proposed method makes virtually no ripple torque, no vibration and less audible noise caused by the injected signal. The difference of impedances between the

Clostridium perfringens has been classified into five toxigenic types (A through E) on the basis of its capability to produce major lethal toxins (alpha, beta, epsilon, and iota toxins). Seroneutralization with mice or guinea pigs has been used to type each toxin, but this conventional method has some disadvantages. Therefore, we used a molecular biological technique to type the bacterium in the present study. A multiplex PCR was developed for this purpose. This method has several advantages in

The rotor position of an interior permanent-magnet synchronous machine (IPMSM) can be estimated without a position sensor by signal injection sensorless control at standstill and/or in very low speed rotating condition. In the signal injection sensorless control, however, the fundamental control performance is limited by the frequency of the injected signal, and no negligible acoustic noise is generated. If the frequency of the injected voltage signal would increase to pulsewidth modulation (PWM

This paper describes a torque, speed, or position control method at standstill and low speed in the interior permanent-magnet motor (IPMM) drive system without any rotational transducer. While IPMMs have originally magnetic saliency, it varies according to the load conditions and the control performance can be easily degraded. In this paper, the saliency or impedance difference is used as the conventional methods and, nevertheless, in order to amplify the difference containing the information of

This paper presents a voltage injection method for reconstructing phase currents from current signals measured on single current-shunt circuits with cost-effective and high-performance configurations in the pulsewidth modulation (PWM) inverters that are used for digital appliances. This method involves the injection of voltage signals at the carrier frequency for reconstructing the phase currents in PWM inverters using a single current sensor in the DC-link. It uses minimum signals to reduce the

This paper presents a position sensorless control scheme of a synchronous reluctance motor (SynRM) combining a high-frequency current injection method in the low-speed region and the flux estimation method based on the stator voltages in the high-speed region. The rotor has inherent saliency, and its angle can be estimated from d-axis stator current injection and the appropriate signal demodulation in a low-speed region. In the high-speed region, the rotor can be estimated by the stator flux fro

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper presents a technique for predicting phase currents in vector-controlled pulsewidth-modulated (PWM) inverters using single dc-link current sensor. There is a limitation for current measurements in the inverters. The measurements are executed in the effective voltages, not in the zero voltage. The current measured in the dc-link and then reconstructed to the phase value is used as a feedback

This paper presents a physical understanding of a high frequency signal injection method to sensorless drives of an induction machine and proposes a sensorless algorithm based on it for zero or low stator frequency operation. The fluctuating high frequency signal at a synchronously rotating reference frame with the fundamental stator frequency generates an asymmetry of the spatial impedances in an induction machine. The difference of impedances between the flux axis and the quadrature axis at hi

This paper describes a torque, speed or position control method at the stand still and low speed in the interior permanent magnet (IPM) motor drive system without any rotational transducer. While IPM motors originally have magnetic saliency, it varies according to the load conditions and the control performance can be easily degraded. In this paper the saliency or impedance difference is used as the conventional methods and, nevertheless, in order to amplify the difference containing the informa

This paper presents a design method for introducing a measurable saliency in the spatial impedances of structurally symmetrical AC machines without any periodic modulation and considerations in selection of AC machines for saliency-based sensorless control. In the structurally symmetrical AC machines such as surface mounted permanent magnet synchronous machine (SMPMM) and induction machine (IM), the saliency in the spatial impedances is built by the spatial saturation on the leakage flux paths.

This paper presents an analysis of inherent position sensors in ac machines. In ac machine drives, the attachment of a mechanical transducer or a structural modification is necessary for zero or low speed operation where the back electromotive force (EMF) is zero or low. However, designs for introducing a measurable saliency in the spatial impedances of structurally symmetrical ac machines without any periodic modulation will make it possible to build sensorless drives at zero or low speed. Thin