Youngdu Yoon

This paper describes a new control algorithm which can enhance the dynamics of a sensorless control system and gives a precise sensorless control performance. Instead of the conventional sinusoidal-type voltage injection, a square-wave-type voltage injection incorporated with the associated signal processing method is proposed in this paper. As a result, the error signal can be calculated without low-pass filters and time delays, and the position estimation performance can be enhanced. Using the

This paper presents a carrier-based modulation method for a matrix converter. By using the offset voltage and changing the slope of carrier, it is possible to synthesize the sinusoidal input currents with the unity power factor and desired output voltages. The proposed method is equivalent to the so called space vector pulsewidth modulation method. The proposed method uses a new point of view to understand the matrix converter modulation method such as the voltage source inverter (VSI) modulatio

This paper presents a sensorless control for induction machines, using square-wave voltage injection. Multiple saliencies are considered, as well as saliency orientation shift according to loading conditions. These two nonideal phenomena severely degrade the performance of sensorless controls for induction machines. Multiple saliencies cause the position error signal to become distorted and make estimation of the rotor flux position difficult. Saliency orientation shift causes the estimated roto

This paper describes a new control algorithm which can enhance the dynamics of a sensorless control system and gives a precise sensorless control performance. When high frequency injection methods with conventional manners (sinusoidal voltage injection) are used, Low pass filters (LPFs) should be used to get an error signal. However, these LPFs degrade sensorless control performances due to the time delay of LPFs themselves. To avoid this effect, the proposed method uses square wave type voltage

This paper presents a new flux weakening algorithm for high saliency Interior Permanent Magnet Synchronous Machine. The proposed method modifies the current reference not by look-up tables, but by a controller in order to achieve a flux weakening. The current reference modification is determined by the d-q axis current and output voltage using the gradient descent method. The proposed method consists of two part, the determination of the flux weakening region and the current reference modificati

This paper presents an application of a disturbance observer for a relative position control system. In this system, since the prefixed motion profile is not defined <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex ante</i> , the acceleration state which is generated based on the profile is also not available. Therefore, feedforward acceleration controls cannot be used, and the position control performance is restricted solely by the bandwidth of th

This paper presents the input power factor control method of the carrier-based modulation method for the matrix converter. It is possible to synthesize the sinusoidal input currents with a desired input power factor and the desired output voltages by changing the slope of the carrier and using the offset voltages. In the proposed method, the input currents are synthesized according to the input current references considering the input power factor. The matrix converter modulation under the unbal

This paper presents a new flux weakening algorithm for a surface mounted permanent magnet synchronous machine. A current reference is modified by a controller in order to achieve a flux weakening. The current reference modification is determined by the d-q currents and the output voltage using the gradient descent method. The proposed method consists of two parts, the determination of the flux weakening region and the current reference modification. The flux weakening region is determined by the

The conventional motion control system simply consists of a PID position controller and a disturbance observer. The estimated speed from the observer has been used to control the speed as a feedback and the estimated disturbance force, which is a byproduct of the observer, has been used to reject the disturbance. However, in this case the disturbance rejection performance should be traded off with speed estimation performance. This paper explains this trade-off using Bode analysis and presents a

This paper presents a flux weakening algorithm for synchronous reluctance motors (SynRMs) based on parameters estimated at standstill. Recently, flux saturated motors have been studied. Flux saturation models were identified and look-up tables were generated based on the saturation model for maximum torque per ampere (MTPA) and flux weakening operations. The operation with tables would degrade the accuracy of operating points when the table size is not enough. The proposed method implements a fl

This paper proposes a new unified power flow controller (UPFC) topology. A single phase of them system with the proposed topology consists of an N:2 transformer with a center tap at the low-voltage side and a power converter module comprising full- and half-bridge converters. A three-phase system can be implemented with three devices. While the conventional UPFC topology uses two three-phase transformers, which are called series and parallel transformers, the proposed topology utilizes three sin

A single‐stage battery charger for light electric vehicles to improve lifetime by removing high‐voltage electrolytic capacitors is suggested. The proposed charger is based on a diode‐clamped series resonant converter equipped with a current‐boosting circuit, which increases the power factor by removing dead zones in the line current. The feasibility of the proposed charger has been verified with a 1.7 kW prototype.

This paper presents a sensorless control for induction machines using a square-wave voltage injection. Multiple saliencies and a saliency orientation shift are considered in this paper. The multiple saliencies make the position error signal distorted and the estimation of the flux position difficult. And, due to the saliency orientation shift, the estimated rotor flux position drifts from the actual rotor flux position according to torque and speed. When the square-wave voltage is injected into