KR102168934B1 - Wireless power transfer device for quench detection system for high field superconducting magnet - Google Patents

Abstract

The present invention provides a wireless power transfer device for a quench detection system of a high field superconducting magnet to transfer power to the quench detection system in a wireless scheme in a state wherein strong field generated from the high field superconducting magnet is applied thereto. In the wireless power transfer device, a transmitter transfers power to a receiver in a wireless scheme. The transmitter includes: an AC/DC converter to convert AC voltage into DC voltage; a driver to modulate a pulse of the DC voltage from the AC/DC converter; and a transmission coil. The receiver includes: a reception coil magnetically coupled with the transmission coil; a rectifier connected with the reception coil to convert AC power into DC power; and a voltage current conditioner to condition output power of the rectifier (51) suitably for a system load (200). The transmission coil and the reception coil configure a magnetically coupled air-core transformer without using a core. Accordingly, the present invention provides the wireless power transfer device for the quench detection system of the high field superconducting magnet for preventing the occurrence of a problem due to a high field without taking up a wide space.

Description

{Wireless power transfer device for quench detection system for high field superconducting magnet}

The present invention relates to a wireless power transmission device for a fault detection system of an ultra high magnetic field superconducting magnet, and more particularly, an ultra high magnetic field superconducting device that wirelessly transmits power to a fault detection system under a condition where a strong magnetic field generated from the high magnetic field magnet is applied. It relates to a wireless power transmission device for a magnet failure detection system.

Superconducting magnet system is a system that operates at cryogenic temperatures (e.g., 4.2K = -268.8°C), and uses liquid helium, a freezer, etc. to maintain cryogenic temperatures, and a high-vacuum cooling container is essential to maintain the cooling temperature. Do. A high-power current, for example, 50kA or more is applied to the fusion superconducting magnet system, and the insulation resistance of the applied power source must be 100 megaohms or more. When a failure (Quench phenomenon) in which the superconducting phenomenon is broken occurs at the junction of the superconducting coil, the resistance value increases and a voltage drop occurs due to a large current. As a result, heat is generated and the temperature of the cooling container rises rapidly. When the temperature rises, the pressure rises and an accident such as an explosion occurs. Therefore, a technology to prevent an accident by detecting a failure of a superconducting magnet as soon as possible is a necessary technology in a superconducting magnet system.

For example, since the late 1980s, ITER, a nuclear fusion energy research project under the support of the International Atomic Energy Agency (IAEA), has been underway as a joint cooperation project between Korea, the United States, the European Union, Japan, Russia, China, and India. International Thermonuclear Experimental Reactor) is a structure that requires a superconducting magnet to generate (heat) ultra-high temperature plasma of more than 100 million °C, and a high magnetic field magnet is required to stably contain the ultra-high temperature plasma in a container. The ITER magnet system applies a superconducting coil, so it applies a strong current of 15MA, a voltage of 56kV DC is applied, and a magnetic field of 10T or more is generated.

In such an extra-large superconducting magnet, when ??chi is generated during operation, the superconducting magnet is transferred to normal conduction and the temperature of the magnet rises, and the refrigerant (liquid helium) of the refrigerator is evaporated due to the temperature increase, and a tremendous pressure is generated. This will explode. In order to prevent this, U.S. Patent No. 10,037,835 proposes a superconducting cable with a structure of protection against teeth, but a quench detection system that detects a quench of a superconducting magnet system in real time regardless of the cable used. system) is essential.

In a general ??value detection system, a high voltage signal is detected by connecting signal lines for each magnet layer. In the case of ITER magnet, hundreds of signal lines are required. The initial voltage at which the ?value is generated is usually 100mV~500mV, and the measured value is very low, but the potential of the superconducting coil can be up to 56kV based on the International Fusion Reactor (ITER) standard. Sensor signals are transmitted through optical cables. However, DC power must be supplied for these optical devices and high voltage signal processors. In addition, it must provide insulation performance for 56kV.

Transformers are generally used for high power high voltage DC-DC conversion. However, in the case of the ITER magnet system, a high magnetic field of about 10T is generated, so the iron core or ferrite core of the transformer is saturated and cannot be used. Therefore, the transformer must be installed as far as possible from the magnet, for example, at a distance of 20m or more, but this requires an additional space and is expensive, and it must be far from the control system, making it difficult to operate. In addition, since the transformer has a large volume and weight, installation is limited, and a stable operation is difficult due to a mechanical attraction and a change in insulation characteristics due to radiation.

The present invention has been made in view of these points, and an object of the present invention is to provide a wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet that does not require an additional space compared to the prior art and does not cause a problem due to a high magnetic field. do. Another object of the present invention is to provide a wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet that has a relatively small volume and weight compared to the prior art.

A wireless power transmission apparatus according to an embodiment of the present invention performs wireless power transmission from a transmitter to a receiver. The transmission unit includes an AC/DC converter for converting an AC voltage into a DC voltage; A driver for pulse-modulating the DC voltage from the AC/DC converter; It includes a transmitting coil. The receiving unit includes: a receiving coil magnetically coupled to the receiving coil; A rectifier connected to the receiving coil to convert AC power into DC power; It includes a voltage current conditioner for conditioning the output power of the rectifier 51 to fit the system load 200. The transmitting coil and the receiving coil form an air-core transformer magnetically coupled without using a core.

A wireless power transmission device according to an embodiment of the present invention includes: a primary side controller disposed in a transmission unit; A secondary controller that communicates with the primary controller by changing the load viewed from the transmitter; It may further include a V / I detector for detecting the load change. In one embodiment, the information transmitted from the secondary-side controller to the primary-side controller includes information on the power received by the receiver.

In one embodiment, the primary-side controller and the secondary-side controller communicate according to the Wireless Power Consortium (WPC) Qi v1.1 communication protocol.

In one embodiment, an impedance matching circuit may be further provided at the end of the transmission coil to maintain stable LC resonance between the transmission and reception coils.

In one embodiment, the transmitting coil and the receiving coil are each wound around a hollow cylinder made of a material that is not affected by a magnetic field.

DC power is supplied to the superconducting magnet and the form of the generated magnetic field is also in DC form.Since, for example, high-frequency power of 100 kH to 370 kHz is transmitted to the wireless transceiver of the present invention, the transceiver is not affected at all by the magnetic field generated by the superconducting magnet. In addition, since power is supplied wirelessly, insulation is possible even at a voltage of 50kV.

As described above, according to the present invention, there is provided a wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet that does not require an additional space and does not cause a problem due to a high magnetic field. In addition, since the iron core or ferrite core is not used, the volume and weight are relatively small compared to the prior art.

1 is a conceptual diagram showing one configuration of a ?-value detection system for a high magnetic field ITER magnet using a wireless power transmission device of the present invention.
2 is a block diagram showing the configuration of a wireless power transmission apparatus according to an embodiment of the present invention.
3 is a circuit diagram showing the configuration of an experimental circuit for a performance experiment of the wireless power transmission device of the present invention.
4 is a photograph showing experimental results when the distance between the transmitting coil and the receiving coil is 5 cm and 10 cm.
5 is a graph showing a result of measuring transmission power according to a distance between a transmitting coil and a receiving coil.
6 is a graph showing transmission efficiency according to a distance between a transmitting coil and a receiving coil.

1 is a conceptual diagram showing one configuration of a ?-value detection system for a high magnetic field ITER magnet using a wireless power transmission device of the present invention.

The ??-value detection unit 200 determines whether ??-value is generated by receiving a magnet voltage signal through a plurality of signal lines. The detection result is converted into an optical signal by the optical converter 210 and transmitted to the central control system. Electric power used by the ?-value detector 200 and the optical converter 210 is provided by the HVSC (High Voltage Signal Conditioner) device 50.

There may be two types of power transmission methods to the HVSC device 50 used as a DC-DC converter. The first type is magnetic coupling (electrical transformer) and the second type is high-frequency capacitive coupling energy transmission. Transformers using magnetic coupling are simple to construct, but are likely to be saturated by the huge magnetic field of the superconducting magnet. In the present invention, wireless power supply to the HVSC is implemented with a transmitting coil and a receiving coil like an electric transformer, but the iron core or ferrite core is not used. That is, the transmitting coil and the receiving coil form an air-core transformer that is magnetically coupled without using a core.

The input part of the HVSC device 50 used as a DC-DC converter is electrically connected in the form of a terminal to a magnet wound with a superconducting wire through a protection system. Since the terminal of the protection system connected to the magnet to which the high power is applied has the same high potential as the superconducting magnet, it must be insulated from the power source driving the sensor.

2 is a block diagram showing the configuration of a wireless power transmission apparatus according to an embodiment of the present invention.

The wireless power transmission device of FIG. 2 includes a transmitting and receiving coil 60 that is magnetically coupled. In the present invention, an iron core or ferrite core for coupling a transmission coil (primary side coil) and a receiving coil (secondary side coil) is not used, and is coupled through air. Power is transmitted from the transmitter to the receiver through the coupled inductor, that is, an air-core transformer (60). The amount of transmitted power can be controlled by feedback (error signal) communication from the secondary side to the primary side. The receiver can communicate with the transmitter by changing the load viewed by the transmitter. This load change causes a change in the transmitting coil current that is measured and interpreted by the processor in the charging module. All of this communication can be done digitally. For example, packets are transmitted from the receiving unit to the transmitting unit. Differential bi-phase encoding can be used for packet transmission and can be operated at a bit rate of 2 kbps, for example. Various types of communication packets such as ID and authentication packets, error packets, control packets, end power packets, and power usage packets may be defined. When the receiver authenticates itself to the transmitter, the transmitter continues to provide power. The receiver maintains control of power transmission using communication packets.

The AC voltage is converted into a DC voltage in the AC/DC converter 10, and the converted DC voltage is pulse-modulated in the driver 20 for DC/DC conversion. The driver 20 modulates the DC voltage with a pulse having a frequency of, for example, 100 kH to 370 kHz. The pulsed power signal from the driver 20 is transmitted wirelessly to the HVSC device 50 via the transmit and receive coil 60. The HVSC device 50 includes a rectifier 51 for converting AC power received through the transmitting and receiving coils 60 into DC power, and a voltage for conditioning the output power of the rectifier 51 according to the system load 200 A voltage current conditioner (52) and a secondary side controller (53) for controlling the operation of the HVSC device (50) are provided. The HVSC device 50 may be configured as a single chip. The HVSC device 50 preferably provides digital control functions compatible with the Wireless Power Consortium (WPC) Qi v1.1 communication protocol. The HVSC device 50 enables a complete contactless power transfer system for a wireless power supply solution with a primary side controller 30 and a V/I detector 40 including a digital controller.

A feedback path is formed from the secondary side controller 53 to the primary side controller 30 to control the power transfer process using the Qi v1.1 communication protocol. The amount of power transferred from the primary side to the secondary side can be controlled by feedback (error signal) communication from the secondary side controller 53 to the primary side controller 30. The secondary side controller 53 can communicate with the transmission unit by controlling the voltage and current conditioner 52 to change the load viewed from the transmission unit.

The V/I detector integrates and controls a low-resistance synchronous rectifier, a low drop-out regulator, a digital control module, and precise V/I information to detect load changes and 2 High efficiency and low power consumption are achieved by acquiring V/I information from the secondary side (receiver) controller and sensing and controlling the voltage and current of the primary side (transmitter). The V/I detector also includes a digital controller that calculates whether the amount of power received by the device is within the limits set in the WPC v1.1 standard, and transmits this information to the primary side (transmitter) controller, whereby the transmitter is equipped with a magnetic interface. ), it is possible to provide high stability in the magnetic field by determining whether there is an external object within

In order to maintain stable LC resonance between the transmitting and receiving coils, an impedance matching circuit may be further provided at the end of the transmitting coil. The impedance matching circuit may be configured as shown in FIGS. 7 and 8, for example. 7 shows a configuration in which an impedance matching circuit between a transmitting coil and a receiving coil is inserted, and FIG. 8 is an equivalent circuit diagram of FIG. 7.

In FIGS. 7 and 8, Vs denotes an output voltage from the driver 20. In the impedance matching circuit of FIGS. 7 and 8, the LC resonance may be implemented by tuning two variable inductance L values. 9 is a graph showing a range of a resonance frequency according to a range of change of Lx1 value, and Table 1 shows an example of inductance and capacitance of each component of the circuit of FIG. 8 when the driving frequency of the driver is 370 kHz.

<Experimental data>

3 shows a configuration of an experimental circuit for a performance experiment of the wireless power transmission device of the present invention. By configuring the circuit of FIG. 3 with a coil and a load having the configuration of Table 2, the transmission power according to the distance between the transmitting coil and the receiving coil was measured. The transmitting coil and receiving coil are wound around a hollow cylinder, and a magnet core is not used. As the material of the cylinder, acrylic, glass, FRP, etc., which are not affected by magnetic fields, can be used.

For example, if the frequency of the pulse driven by the driver is 100 kHz, the diameter of the winding coil is 30 cm, the length of the transmission/reception coil is about 10 m (10 turns), and the C:80 nF for LC resonance is configured. When the frequency of the pulse driven by the driver is 370 kHz, the diameter of the winding coil is 30 cm, the length of the transmission/reception coil is about 4 m (4 turns), and the C for LC resonance is about 25 nF.

In order to compare the power transfer rate fairly, the power reflectance was maintained at 5% or less according to the distance change. The experiment was conducted with an RF input power of 100KHz 150W. Table 1 shows the specifications of the resonance coil, HTS (High Temperature Superconducting) magnet and permanent magnet used in the experiment. 4 is a photograph showing experimental results when the distance is 5 cm and 10 cm. As the distance increases, the transmission power certainly decreases rapidly. In general, a thermally coupled loss of a resonance line is caused by an AC loss, which is the sum of a magnetization loss and a transport current loss during AC charging in an AC magnetic field. The resonant coupling coil can also cause heat loss depending on the LC resonant conditions in the resonantly coupled coil. The LC resonance of the transmitting coil and the receiving coil forms a source resonance circuit, and the resonance coupling coil applies a resonance method, so a non-radiative magnetic field is generated.

5 shows a result of measuring transmission power according to the distance between the transmitting coil and the receiving coil. When the distance between the transmitting coil and the receiving coil exceeds 50mm, the transmit power rapidly decreases even though strong resonance coupling between the transmitting coil and the receiving coil is maintained.

6 shows transmission efficiency according to the distance between the transmitting coil and the receiving coil. It can be seen that the transmission efficiency is greatly improved when the input power is 100W or more, and gradually increases to 150W. In other words, this means that it must be considered that a minimum input power is required to maintain a strong resonance coupling.

In the above, although the present invention has been described with reference to several examples, the present invention is not necessarily limited to these embodiments, even though it has been described that all the components constituting the embodiments of the present invention are combined into one or operated in combination. That is, within the scope of the object of the present invention, all the constituent elements may be selectively combined and operated in one or more. In addition, some or all of the components may be selectively combined and implemented as hardware or a computer program.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

10 AC/DC converter,
20 actuator,
30 primary side controller,
40 V/I sensor,
50 HVSC devices,
60 air core transformer.

Claims (6)

As a wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet for wireless power transmission from the transmitter to the receiver,
The transmission unit,
AC/DC converter for converting AC voltage to DC voltage;
A driver for pulse-modulating the DC voltage from the AC/DC converter;
It includes a transmitting coil,
The receiving unit,
A receiving coil magnetically coupled to the transmitting coil;
A rectifier connected to the receiving coil to convert AC power into DC power;
A voltage current conditioner that conditions the output power of the rectifier 51 according to the system load 200
Including,
The transmitting coil and the receiving coil are each wound around a hollow cylinder made of acrylic, glass, or FRP material,
The transmitting coil and the receiving coil form an air-core transformer magnetically coupled without using a core,
A wireless power transmission device for a fault detection system of a superconducting magnet in an ultra-high magnetic field.
The method of claim 1,
A primary side controller disposed in the transmission unit;
A secondary controller that communicates with the primary controller by changing the load viewed from the transmitter;
A V/I detector that detects the load change;
A wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet further comprising a. The method of claim 2,
The information transmitted from the secondary-side controller to the primary-side controller includes information on the power received by the receiving unit, a wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet. The method of claim 3,
The primary-side controller and the secondary-side controller communicate with each other according to a Wireless Power Consortium (WPC) Qi v1.1 communication protocol, a wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet. The method of claim 1,
A wireless power transmission device for a fault detection system of an ultra-high magnetic field superconducting magnet, further equipped with an impedance matching circuit at the end of the transmitting coil to maintain stable LC resonance between the transmitting and receiving coils. delete

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