This letter presents a position sensorless control method of brushless DC (BLDC) motors considering unbalanced zero crossing detection of back electromotive force (back EMF). The zero-crossing point (ZCP) of back EMF voltage is detected by comparing the DC-link voltage with the back EMF voltage. The unbalanced ZCP detection is caused by the DC-link voltage drop, DC-link offset voltage, and a motor having asymmetric back EMFs. Because the sensorless BLDC motor control is based on unbalanced ZCP detection, issues with torque ripple and current ripple may be increased. Therefore, sensorless operation with unbalanced ZCP detection may be unstable. In this study, an improved sensorless control method based on a simple compensation algorithm using ZCP signals is proposed. Using the proposed control method, balanced commutation instants can be obtained and the benefits of high-performance operation of BLDC motors can be accomplished. Through application of the proposed method, the effectiveness of the proposed method was experimentally verified.

This study proposes an interior permanent magnet (IPM) brushless dc (BLDC) motor design strategy that utilizes BLDC control based on Hall sensor signals. The magnetic flux of IPM motors varies according to the rotor position and abnormal Hall sensor problems are related to magnetic flux. To find the cause of the abnormality in the Hall sensors, an analysis of the magnetic flux density at the Hall sensor position by finite element analysis is conducted. In addition, an IPM model with a notch structure is proposed to solve abnormal Hall sensor problems and its magnetic equivalent circuit (MEC) model is derived. Based on the MEC model, an optimal rotor design method is proposed and the final model is derived. However, the Hall sensor signal achieved from the optimal rotor is not perfect. To improve the accuracy of the BLDC motor control, a rotor position estimation method is proposed. Finally, experiments are performed to evaluate the performance of the proposed IPM-type BLDC motor and the Hall sensor compensation method.

This letter presents an improved approach for high performance operation of brushless dc (BLDC) motors with hall sensors. The hall sensors in BLDC motors are ideally placed 120 electrical degrees apart. However, hall sensor placement may be significantly incorrect, particularly in high-pole and small-sized motors. These misaligned hall sensors can cause serious torque ripple, and it can be difficult to apply advanced angle control. Therefore, a position error compensator is needed before an advanced angle control method is applied. In this letter, on the basis of the position error compensator, an online advanced angle adjustment method using input voltage and input current is proposed. Using the proposed method, balanced hall sensor signals can be obtained and the high-performance operation can be achieved. The effectiveness of the proposed approach is verified through experimental results.

This study proposes a damping control strategy for high-speed operation of a wave energy converter (WEC). The control strate-gy of WEC is based on the heave-motion (up/down motion) mechanism of buoy. The applied WEC system extracts power through damping control of the permanent magnet linear genera-tor, which is directly connected to the buoy. This study first ana-lyzed the mechanical dynamics of a WEC system. Further, a damping control method that could improve the extracted power for a wide speed range is examined. The results showed that the operating region could be expanded and the power extraction could be maximized using only the proposed software implemen-tation, without requiring additional hardware. The validity and benefits of the proposed control algorithm were experimentally verified using a down-scaled WEC model.

This paper presents a stator winding temperature detection method for permanent magnet synchronous motors (PMSMs) using a motor parameter estimation method. PMSM performance is highly dependent on the motor parameters. However, the motor parameters vary with temperature. It is difficult to measure motor parameters using a voltage equation without additional sensors. Herein, a stator winding temperature estimation method based on a d-axis current injection method is proposed. The proposed estimation method can be used to obtain stator temperatures and to achieve reliable operation. The validity of the proposed method is verified through simulations and experimental results.

In order to save resources and prevent global warming, there has been a pressing need in recent years to reduce the volume of CO2 emissions, and to improve the fuel consumption of automobiles. The trend in the automotive application is to improve efficiency and to reduce volume and weight. Under these circumstances, the mechanical parts in the automobile industry are being replaced by electronic methods. Especially, to improve vehicle engine efficiency, power transmission and around the field of devices according to driving conditions need to be properly cooled. Conventional mechanical water pump is directly connected by the engine belt. For this reason, regardless of coolant circulation, the conventional mechanical water pump is always operated. The way which the mechanical water pump is replaced by electric water pump could reduce energy consumption.