scholarly journals AC Losses Analysis in stack of 2G HTS tapes in a coil

2020 ◽  
Author(s):  
Vasily Zubko ◽  
Sergey Fetisov ◽  
Sergey Zanegin ◽  
Vitaly Vysotsky
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Transport Current ◽  
Ac Loss ◽  
Ac Losses ◽  
Electrical Machine ◽  
Power Cables ◽  
Fem Model ◽  
Model Coil ◽  
Computational Speed

The model coil with the racetrack geometry based on second generation (2G) High Temperature Superconducting (HTS) tapes has been developed for an electrical machine where a winding pack is a stack of 2G HTS tapes. It is important to evaluate transport current AC losses and possible methods to reduce them in a winding. In a device made of 2G HTS tapes, the main the AC losses are the hysteresis ones. Only numerical simulation permits to predict them in full. The FEM model for calculation of the hysteresis losses developed before for 2G HTS power cables was modified for a stack of the 2G HTS tapes in a coil. In this paper the methods to increase a computational speed are presented. Possible ways to reduce AC losses are discussed also. The details of the model and comparisons of calculations with measurements of the AC loss are presented.<br>

scholarly journals AC Losses Analysis in stack of 2G HTS tapes in a coil

2020 ◽  
Author(s):  
Vasily Zubko ◽  
Sergey Fetisov ◽  
Sergey Zanegin ◽  
Vitaly Vysotsky
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Transport Current ◽  
Ac Loss ◽  
Ac Losses ◽  
Electrical Machine ◽  
Power Cables ◽  
Fem Model ◽  
Model Coil ◽  
Computational Speed

The model coil with the racetrack geometry based on second generation (2G) High Temperature Superconducting (HTS) tapes has been developed for an electrical machine where a winding pack is a stack of 2G HTS tapes. It is important to evaluate transport current AC losses and possible methods to reduce them in a winding. In a device made of 2G HTS tapes, the main the AC losses are the hysteresis ones. Only numerical simulation permits to predict them in full. The FEM model for calculation of the hysteresis losses developed before for 2G HTS power cables was modified for a stack of the 2G HTS tapes in a coil. In this paper the methods to increase a computational speed are presented. Possible ways to reduce AC losses are discussed also. The details of the model and comparisons of calculations with measurements of the AC loss are presented.<br>

scholarly journals Measurements and Analysis of AC Losses in HTS Windings of Electrical Machine for Different Operation Modes

2021 ◽  
Vol 11 (6) ◽  
pp. 2741
Author(s):  
Sergey Zanegin ◽  
Nikolay Ivanov ◽  
Vasily Zubko ◽  
Konstantin Kovalev ◽  
Ivan Shishov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
High Temperature Superconductor ◽  
High Temperature Superconductors ◽  
Transport Current ◽  
Operating Conditions ◽  
Ac Losses ◽  
Electrical Machine ◽  
2Nd Generation ◽  
Motor Mode

The article is devoted to the study of losses in devices based on high-temperature superconductors of the 2nd generation. The complexity of the devices under study increases from a single rack coil to a winding assembled from several coils, and finally to an electric machine operating in generator mode. This is the way to experimentally study the behavior of 2nd generation high temperature superconductor (2G HTS) carrying a transport current in various conditions: self-field, external DC, and AC magnetic field. Attention is also paid to the losses in the winding during its operation from the inverter, which simulates the operating conditions in the motor mode of a propulsion system.

AC Loss Characteristics of Stacks of YBCO Coated Conductors

2006 ◽  
Vol 946 ◽  
Author(s):  
Francesco Grilli ◽  
Stephen P. Ashworth ◽  
Svetlomir Stavrev
Keyword(s):  
Magnetic Field ◽  
Transport Current ◽  
Point Of View ◽  
Coated Conductors ◽  
Ac Loss ◽  
Ac Losses ◽  
Practical Applications ◽  
Superconducting Coils ◽  
Loss Characteristic ◽  
Ybco Coated Conductors

ABSTRACTPractical applications of YBCO coated conductors (CC) involving superconducting coils will utilize tapes packed together in an arrangement resembling a vertical stack. In such configuration there is an important electromagnetic interaction between the tapes, which strongly influences the loss characteristic of the device.In the presence of an external magnetic field, the losses are reduced compared to an isolated tape because of the reduced aspect ratio of the conductor and, at least for low fields, because of an effective screening of the central part of the stack. On the contrary, in the case of AC transport current, the losses tend to increase due to the enhancement of the local field caused by the interaction of the self-field produced by neighboring tapes. In practical situations the conductor is usually subjected to both transport current and magnetic field, so that there is a trade-off between the two effects.In this paper we investigate, both experimentally and by means of finite-element method calculations, the ac loss behavior of a stack composed by a finite number of tapes in different working conditions, and we compare the AC losses to the ones of non-interacting tapes in order to determine if the use of stacked tapes is advantageous from the point of view of power dissipation.

Temperature Dependence of Total AC Loss in High-Temperature Superconducting Tapes

2009 ◽  
Vol 19 (4) ◽  
pp. 3637-3644 ◽  
Author(s):  
Doan N. Nguyen ◽  
Pamidi V. P. S. S. Sastry ◽  
David C. Knoll ◽  
Justin Schwartz
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Temperature Dependence ◽  
High Temperature Superconductors ◽  
Ac Loss ◽  
Ac Losses ◽  
Transport Losses ◽  
Set Up ◽  
Interesting Behavior ◽  
The Magnetic Field

A versatile experimental facility was designed and set up to measure transport ac losses, magnetization ac losses, and total ac losses in high-temperature superconductors at variable temperatures. Several sets of measurements were carried out in the temperature range of 35 K to 100 K. Sample temperature during the measurements could be controlled within plusmn0.5 K of set temperature. Temperature dependence of transport losses reflects variation of critical current density of the tapes with temperature. Temperature dependence of magnetization losses exhibits an interesting behavior with a peak, whose position shifts to lower temperatures as the magnetic field is increased. Experimental data of ac losses at various temperatures are compared with those calculated using numerical methods. Generally, the simulated results reproduce well the experimental data.

scholarly journals AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

2020 ◽  
Author(s):  
Yawei Wang
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductor ◽  
Eddy Currents ◽  
Ac Loss ◽  
Ac Losses ◽  
Induced Current ◽  
Risk Optimization ◽  
Current Flows ◽  
The Stability

<p>No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments. </p>

scholarly journals AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

2020 ◽  
Author(s):  
Yawei Wang
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductor ◽  
Eddy Currents ◽  
Ac Loss ◽  
Ac Losses ◽  
Induced Current ◽  
Risk Optimization ◽  
Current Flows ◽  
The Stability

<p>No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments. </p>

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