High Frequency Induction Research Articles

Enhanced Linear ADRC Strategy for Sensorless Control of IPMSM Considering Cross-Coupling Factors

Estimation of rotor coordinate system by high-frequency (HF) signal injection is an effective sensorless control strategy, which can solve the decoupling problem of position information of interior permanent magnet synchronous motor (IPMSM) in the low-speed range. However, the inductance cross-coupling phenomenon caused by magnetic saturation will lead to a decline in the accuracy of rotor angle extraction, resulting in a serious deterioration of the sensorless control performance. To solve this problem, an HF signal injection method considering <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-q</i> axis coupling inductance is proposed to estimate HF inductance and the rotor angle. The estimated HF inductor combined with the current loop enhanced linear active disturbance rejection control (ELADRC) is used in the current loop control to estimate the disturbance and improve the current regulation quality of the current control system. Furthermore, the stability and the tracking performance of the enhanced LADRC are analyzed theoretically. Finally, the stability of a closed-loop IPMSM drives system based on ELADRC considering HF inductance is analyzed. The experimental results of a salient pole IPMSMs driver verify the effectiveness and practicability of the scheme.

Microstructure and mechanical properties of ZrO2 fiber toughened Al2O3/ZrO2(Y2O3) solidified ceramics prepared with high frequency induction zone melting

ZrO2 fiber toughened and non-fiber toughened Al2O3/ZrO2(Y2O3) directionally solidified eutectic ceramics (DSECs) were prepared via high frequency induction zone melting method, and the effects of both the fibers and the growth rate on the microstructure and mechanical properties were investigated. The results showed that both the fiber toughened and the non-fiber toughened DSECs were composed of α-Al2O3, c-ZrO2 and m-ZrO2, and their microstructures were all typical colony structure. The phase spacing in intracolony (λ) for these two kinds of DSECs gradually decreased with the increase of growth rate (ν), they satisfied λ = 10.31ν−1/2 and λ = 13.65 v−1/2, respectively. And the minimum values of λ were 2.33 ± 0.25 µm and 2.99 ± 0.17 µm, respectively, i.e., that is ZrO2 fiber decreased the phase spacing in intracolony about 22%. The fracture toughness for these two DSECs increased continuously with the growth rate, reached the maximum values of 5.72 ± 0.20 MPa m1/2 and 3.95 ± 0.23 MPa m1/2 at 30 mm/h, respectively, i.e., the former was about 1.45 times of the latter. At the same growth rate, the fracture toughness of ZrO2 fiber toughened DSEC were obviously higher than those of DSEC without fiber. When they encounter fibers with high elastic modulus during their propagation, the cracks will undergo deflection, bifurcation, or bridging, and the fibers will undergo debonding and pulling-out under the external stress, both of which consume a large amount of crack propagation energy and achieve toughening effect.

Magnetic Integration for Multiple Resonant Converters

A universal integration method for the magnetic components (MCs) of multiple resonant converters is proposed in this article. Two rules for integration of multiple independent MCs are summarized, one of which is to keep functional independent of MCs after integration, while the other is to achieve lower loss and volume through integration. Following the proposed rules and by dividing an MC into winding-part and nonwinding-part, integration is achieved by sharing the nonwinding-part of the MCs. An input-series output-parallel (ISOP) resonant converter is taken as an example to show how integration is accomplished step by step. It is shown that, both volume and loss of the magnetic cores are reduced after integration of all the high frequency transformers and inductors. Detailed theoretical analysis, finite element analysis simulations and comparisons have been presented. A 600 V–800 V input, 28 V/2000 W-output ISOP resonant converter was built. Experimental results have been provided to verify the effectiveness and feasibility of the proposed integration methods.

Investigation of Heat Transfer Regimes in Subsonic Dissociated-Nitrogen Jets of a High-Frequency Induction Plasmatron under Additional Surface Heating by Laser Radiation

Investigation of Heat Transfer Regimes in Subsonic Dissociated-Nitrogen Jets of a High-Frequency Induction Plasmatron under Additional Surface Heating by Laser Radiation

The Use of the Linear Energy Calculation Model in High-Frequency Induction (HFI) Tube Welding Technology to Obtain Optimal Microstructure and Weld Geometry

The article presents a calculation model of the linear energy of welding P235GH steel tubes with high-frequency currents in order to obtain an optimal microstructure and geometry of the weld of high internal purity. The model was developed based on real data for the standard linear energy used in the steelworks Huta Łabędy and presented as the power factor P/V and P/(V·t), where P is the power [kW], V the production speed [m/min] and t the wall thickness. The model can be used for two ranges of pipe diameters: 114.3–168.3 mm and 219.1–323.9 mm. The data from the model were implemented into the High Frequency Induction (HFI) control panel of Huta Łabędy in order to produce test tubes which were subsequently tested with ultrasounds to verify the quality of the internal weld. In addition, samples were taken for metallographic analysis, which was supposed to check whether the applied linear energy calculation model allows the obtainment of the optimal weld geometry and the optimal angle of the metal flow line allowing for swelling and the extrusion of melted impurities from the inside of the joint by the squeeze rolls. The metallographic analysis also determined the nature of the occurrence of ferrite inside of the center diffusion bond and the zonal microstructure of the joint, the control of which is based on the correlation of the parameters of the mechanical process of forming the tube with the linear energy of welding. Carrying out the technological and technical process based on the applied HFI linear energy calculation model allowed us to obtain a weld of high purity and metallurgical consistency. This model can be used in the future on an industrial scale for the production of pipes using the HFI method.

Microstructure, mechanical property and cutting performance of (Ti,W)C/Mo/Co/Ni cermet tool material prepared by spark plasma sintering and high frequency induction heating

The (Ti,W)C/Mo/Co/Ni cermet tool material is produced using a combination of spark plasma sintering and high frequency induction heating (HFIH-SPS) mixed sintering technology. This study investigates the influence of various sintering parameters on the microstructure and mechanical properties of (Ti,W)C/Mo/Co/Ni cermet tool material. The findings indicate that the rapid sintering densification of (Ti,W)C/Mo/Co/Ni cermet tool material can be achieved by the mixed sintering technology at a lower sintering temperature. The rapid sintering process observed in this study can be mainly attributed to the plasma activation effect generated by pulse current and the Joule heat effect produced by the metal particles under high frequency induction. The optimized relative density of the (Ti,W)C/Mo/Co/Ni cermet tool material reaches 99.10%, with the hardness of 20.28 ± 0.58 GPa, the fracture toughness of 7.74 ± 0.14 MPa·m1/2 and the flexural strength of 796.12 ± 36.55 MPa. The indentation of (Ti,W)C cermet exhibits a regular cross shape, and the indentation edge is smooth, which indicates a good fracture toughness. The high mechanical properties of (Ti,W)C/Mo/Co/Ni cermet tool material are mainly attributed to the interaction between crystal grain boundary solute strengthening and dislocation movement. The tool has shown good cutting performance during the subsequent dry cutting of 40Cr steel, with the lowest surface roughness Ra value of 1.097 µm.

Al-Li-Cu Alloy Preparation by High-energy Ball Milling Sintered Using High Frequency Induction Heating.

Al-Li-Cu Alloy Preparation by High-energy Ball Milling Sintered Using High Frequency Induction Heating.

Al-Graphite Nanostructures Composites Fabricated by High-Frequency Induction Sintering Method.

Al-Graphite Nanostructures Composites Fabricated by High-Frequency Induction Sintering Method.

High-Frequency Induction Heat Sintering of Al2O3/Al7075 Composites.

High-Frequency Induction Heat Sintering of Al2O3/Al7075 Composites.

Predicting Operating Windows for High-Frequency Induction Aluminum Tube Welding

High-frequency (HF) induction welding is a practical welding technique widely used in various industries. Although it is generally robust, HF induction welding of aluminum tubes is complicated by the very high line speed, which requires high and accurate power input, and, therefore, a small fluctuation or variation in power input could result in drastically different welds. This work is dedicated to analyzing the influence of welding parameters, line speed, power input, and other unknown random factors, such as those induced by weather or work shift, especially those induced by the change of aluminum stock and adjustment/maintenance of the induction welding coil. Through the machine learning process, statistical models defining the normal operating windows were developed based on experimental data. The operating windows, defined by the overheat-normal and normal-cold boundaries, are expressed in terms of probabilities of producing normal welds. These trained models can be used to make new predictions, i.e., new operating windows, by collecting a small sample (a very limited number of calibrating data points). This procedure was verified experimentally.

Investigation of Heat Transfer Regimes in Subsonic Dissociated-Nitrogen Jets of a High-Frequency Induction Plasmatron under Additional Surface Heating by Laser Radiation

The heat transfer to a cylindrical water-cooled copper model was experimentally investigated in an induction VGU-4 high-frequency (HF) plasmatron of the Institute for Problems in Mechanics of the Russian Academy of Sciences. The model, 30 mm in diameter, equipped with a calorimetric transducer with a heat-adsorbing graphite surface, 13.8 mm in diameter, was exposed to the surface heating in the combined regime by nitrogen plasma and laser radiation and in the cases of the heating with only laser radiation or a nitrogen plasma jet. The experiments in the HF-plasmatron jets were performed at the pressure in the setup low-pressure chamber p = 1 × 104 Pa, nitrogen mass flow rate G = 2.4 g/s, and the plasmatron HF-generator anode power Na.p. = 22 kW. It is established that in the chosen experimental regimes the dissociated-nitrogen jet and the high-frequency induction discharge do not produce a considerable effect on the laser beam passing through them. The values of the heat flux density are obtained as functions of the laser radiation power delivered. The subsonic nitrogen plasma flow in the quartz discharge channel and in the low-pressure chamber of the VGU-4 setup is numerically modeled under the experimental conditions basing on the solution of the complete Navier–Stokes equations using the Patankar–Spalding method.

Thermal effects of electromagnetic origin from heating processes to biological disturbances due to field exposure—A review

This contribution aims to appraise, analyze and evaluate the literature relating to the interaction of electromagnetic fields (EMF) with matter and the resulting thermal effects. This relates to the wanted thermal effects via the application of fields as well as those uninvited resulting from exposure to the field. In the paper, the most popular EMF heating technologies are analyzed. This involves on the one hand high frequency induction heating (HFIH) and on the other hand microwave heating (MWH), including microwave ovens and hyperthermia medical treatment. Then, the problem of EMF exposure is examined and the resulting biological thermal effects are illuminated. Thus, the two most common cases of wireless EMF devices, namely digital communication tools and inductive power transfer appliances are analyzed and evaluated. The last part of the paper concerns the determination of the different thermal effects, which are studied and discussed, by considering the governing EMF and heat transfer (or bio heat) equations and their solution methodologies.

Development of the High Frequency Induction Heating Device

1．はじめに

A Nonintrusive Digital Current Sensing Method for DC–DC Converters With Wide Load Range

Current estimators for dc-dc converters reduce the requirement of current transducers (e.g. sense resistor, Hall sensor) which may be either expensive, invasive, and (or) require additional signal conditioning circuits. High-frequency inductor currents within dc-dc converters can be estimated instantaneously using voltage measurements taken at its terminals. The voltage measurement at the switching terminal of the inductor is assisted by a comparator, whose output state is related to the corresponding voltage magnitude. This paper presents a novel unified current estimation method in which a single comparator is required to detect the switch node status both in continuous and discontinuous modes of operation. The other measurements required for this method include sensing dc voltage magnitudes, which are essential measurements for a regulated dc-dc converter system; hence the proposed methodology can be easily integrated into existing digital control schemes. The proposed approach has been applied to first-order dc-dc converters and has been validated using a laboratory prototype of a digitally controlled boost converter system using an FPGA.

Comparative Study of Magnet Temperature Estimation at Low Speeds Based on High-Frequency Resistance and Inductance

Interior permanent magnet synchronous motors have been widely used in electric vehicles. These motors employ Nd-Fe-B as the permanent magnet, which is vulnerable to temperature variations. Moreover, some features of Nd-Fe-B magnets are related to temperature, which can affect motor characteristics. Therefore, magnet temperature is an important parameter and methods for estimating it have been developed. In particular, a signal injection method has been developed for low-speed regions. In this method, two parameters are employed: high-frequency resistance and high-frequency inductance. In this paper, these two methods are compared to determine which parameter is more appropriate for estimations at low speeds and to reveal whether signal injection methods can be applied to the standstill condition. The comparison indicated that the high-frequency inductance-based method has a stronger correlation with the magnet temperature at low speed and standstill conditions than the high-frequency resistance-based method.

Equivalent circuit of high frequency inductor to consider eddy currents and resonance

The resistance and inductance of an inductor working at high frequencies depend on frequency because of eddy currents caused by the skin and proximity effects. In addition, the stray capacitance among winding coils would give significant influence. This paper proposes an equivalent circuit model which can consider the displacement and eddy currents simultaneously in frequency and time domain. In the proposed circuit model, the capacitance and complex inductance are determined by solving electrostatic and magnetostatic equations with finite element method (FEM). It is shown that the input impedance of an air-core coil is consistent with that computed by FEM at low frequencies. Moreover, the former is shown to be consistent with the measured result.

Heat-input factor effect on the quality of high-frequency induction welded pipe for oil and gas industry

High Frequency Induction Welded (HFIW) pipes with one longitudinal seam has the potential to replace the seamless pipes in the oil and gas industry. The heat-input factor (i.e., welding power to line speed ratio) and squeeze force are important manufacturing input parameter to control the quality of HFIW pipes. This study found increase in heat input factor led to an increased tensile strength and toughness in HFIW pipes with a compromise in hardness in the weld zone.

Intensive Emission of Droplets during Melting of Metal Samples in a High-Frequency Inductor

Intensive Emission of Droplets during Melting of Metal Samples in a High-Frequency Inductor

Effect of Full Baking on Carbon Measurement by High Frequency Induction Combustion Infrared Absorption Method

In this study, the sample and multicomponent flux are put into the crucible and fully baked. The color change of multicomponent flux during baking indicates the degree of baking, which is appropriate when multicomponent flux turns light red. Through specific tests, different grades of superalloys are used to carry out the comparison test between full baking and non-baking. The measurement precision after full baking is generally higher than that without baking. The difference in value cannot be predicted. Also, the difference cannot be eliminated by adding a correction factor, it can only be eliminated by full baking. After full baking, it can be seen quantitatively from the blank influence value that the blank has little interference with the measurement of low carbon, and the influence on the measurement of high carbon is negligible.

Stator Winding Temperature and Magnet Temperature Estimation of IPMSM Based on High-Frequency Voltage Signal Injection

The interior permanent-magnet synchronous motor (IPMSM) has been widely used as the traction motor in electric/hybrid vehicles because of its high torque density and wide operating speed range. During the operation of the IPMSM, the stator winding temperature and magnet temperature should be monitored to prevent winding insulation breakdown and irreversible demagnetization and to improve the torque accuracy. This article devised a method involving the use of a high-frequency (HF) resistance and an HF inductance for estimating these two temperatures at low motor speeds. The relationship between the HF impedance and both temperatures was determined and verified using an experimental setup in which both temperatures could be measured. Based on the relation, the temperature estimation method has been proposed, in this article, and verified by the experimental test. The proposed method was used to estimate the stator winding and the magnet temperatures simultaneously for 6000 s, and the maximum error was 6 °C and 3 °C for the stator winding and magnet temperature, respectively, even when the load and the temperatures varied considerably.