JP4419588B2 - Superconducting motor device - Google Patents

Description

  The present invention relates to a superconducting motor device, and more particularly, to a superconducting motor device used in an electric vehicle or a hybrid vehicle that performs non-contact power feeding to a superconducting coil provided on a rotor and cools it with high efficiency.

  In recent years, in order to improve the exhaustion of fuel resources such as gasoline and the deterioration of the environment due to the exhaust gas of an internal combustion engine, the development of electric vehicles and hybrid vehicles that run by driving a motor with electricity has been promoted. When a normal conducting motor is used, there is a problem that it is difficult to increase the output because copper loss occurs due to electric resistance, resulting in low efficiency and a limited current. Therefore, as disclosed in Japanese Patent Laid-Open No. 6-6907, if a superconducting motor is employed, copper loss in the superconducting coil is eliminated and high efficiency is achieved, and the motor itself can be reduced in size and output. it can.

  With regard to the superconducting motor described above, research on the configuration in which the superconducting coil is arranged in the rotor is being promoted particularly for the purpose of strengthening the rotor field. It becomes. As a power supply method, a method of supplying power using a brush to a sliding portion, or a method of supplying power to a rotor using non-contact power supply (also referred to as induction power supply) has been considered recently.

Since the inductive power supply received in a contactless manner on the rotor side is an alternating current, it is necessary to rectify the alternating current into a direct current using an exchanger. This exchanger uses semiconductor elements, and the semiconductor elements generate heat and need to be cooled. However, the temperature at which the semiconductors operate most efficiently is generally lower than room temperature, and normal cooling methods such as water cooling and air cooling. Then there is a problem that sufficient cooling is difficult.
JP-A-6-6907

  The present invention has been made in view of the above problems. When a superconducting coil is provided in a rotor of a superconducting motor, non-contact power feeding is performed on the superconducting coil, and the alternating current obtained on the rotor side is changed to direct current. The objective is to cool the vessel with high efficiency.

In order to solve the above problems, the present invention is provided with non-contact power feeding means for performing inductive power feeding between a rotor and a stator, and a converter for converting alternating current into direct current and a superconducting coil are fixed to the rotor. A superconducting motor device that converts alternating current received on the rotor side by the non-contact power feeding means into direct current by the converter and feeds power to the superconducting coil,
The superconducting coil is disposed in a cooling space in the rotor, and a refrigerant introduction path through which a refrigerant is supplied from the outside to the cooling space, and a refrigerant from which the refrigerant whose temperature has been raised by heat exchange with the superconducting coil is discharged. There is provided a superconducting motor device provided with a lead-out path, wherein the converter is cooled by the refrigerant whose temperature has risen in the refrigerant lead-out path.

  With the above configuration, in order to suitably maintain the operating characteristics of the converter that converts the alternating current after non-contact power supply to direct current to supply power to the superconducting coil, the heated refrigerant after cooling the superconducting coil is diverted. Thus, it is not necessary to separately provide a cooling means dedicated to the converter, and the converter that may have a higher cooling temperature than the superconducting coil can be efficiently cooled.

The superconducting coil fixed to the rotor is for field use, and a plurality of armature coils are fixed to the stator side at intervals in the circumferential direction.
The superconducting coil is fed and excited to make the rotor side an electromagnet, and the rotor is rotated by generating a rotating magnetic field by sequentially feeding each of the plurality of armature coils.

  With the above configuration, when the superconducting coil serving as the field coil is excited to become an electromagnet, the rotating magnetic field generated by sequentially feeding the plurality of armature coils on the stator side in the circumferential direction causes the rotor to rotate synchronously. Thus, a rotational driving force can be obtained.

  A temperature control unit that adjusts the temperature of the refrigerant heated by heat exchange with the superconducting coil to a specific temperature is interposed in the refrigerant outlet path.

  With the above configuration, the superconducting coil has been cooled to the optimum operating temperature of the converter and then supplied to the converter so that the converter is not overcooled or not cooled sufficiently. be able to.

  The transducer uses a silicon carbide (SiC) semiconductor element.

  With the above configuration, silicon carbide (SiC) has a high band voltage and a high non-electrolytic strength compared to a conventional semiconductor element made of a silicon substrate. It is most suitable as a semiconductor element of a converter when flowing.

  The temperature of the refrigerant supplied from the refrigerant outlet path to the converter is adjusted to −100 ° C. to 0 ° C. by the temperature control unit.

  The temperature range in which the above-described SiC semiconductor element can be operated with the least electrical resistance is in the range of −100 ° C. to 0 ° C., which has been found by the inventors' diligent research described later. As described above, the performance of the converter can be optimized by controlling the refrigerant temperature in the refrigerant outlet path in the range of −100 ° C. to 0 ° C. by the adjustment unit as described above.

  The non-contact power feeding means is surrounded by an electromagnetic shielding material.

  In this way, by surrounding the non-contact power supply means that supplies power by electromagnetic induction with the electromagnetic shielding material, the magnetic field generated by the non-contact power supply means is prevented from adversely affecting surrounding electronic devices and various communication devices. be able to.

The electromagnetic shielding material preferably covers the outer surface of the stator.
In this way, the magnetic field generated by the non-contact power feeding means and the magnetic field generated by the superconducting coil and armature coil can be collectively shielded so as not to leak outside.

The refrigerant is liquid hydrogen or liquid nitrogen.
Although the superconducting coil needs to be cooled to a very low temperature, the liquid hydrogen has a boiling point of about −252.8 ° C. and liquid nitrogen has a boiling point of about −195.8 ° C. Superconducting performance can be suitably exhibited by using hydrogen or nitrogen in the state as a refrigerant.

It is mounted on an electric vehicle that generates electricity by reacting hydrogen stored in a liquid hydrogen tank with oxygen by a fuel cell,
Liquid hydrogen in the liquid hydrogen tank is used as the refrigerant, and hydrogen gas evaporated through the refrigerant introduction path, the refrigerant space, the refrigerant outlet path, and the converter is supplied to the fuel cell for power generation. The electric power is supplied to the superconducting coil and the armature coil.

  With the above configuration, by mounting a superconducting motor device for driving an electric vehicle equipped with a fuel cell that reacts hydrogen and oxygen, the on-vehicle liquid hydrogen can be used as a coolant for cooling the superconducting coil and the converter. be able to. In addition, by supplying hydrogen gas that has been heated and vaporized by cooling the superconducting coil and the converter to the fuel cell, there is no need to separately provide a device for vaporizing liquid hydrogen in the liquid hydrogen tank, which is efficient. Furthermore, the driving force of the superconducting motor device can be obtained by feeding the electric power generated by the fuel cell to the superconducting coil and the armature coil.

  As is clear from the above description, according to the present invention, in order to suitably maintain the operating characteristics of the converter that converts alternating current into direct current, cooling is performed by diverting the heated refrigerant after cooling the superconducting coil. By doing so, the converter can be cooled efficiently. Moreover, the converter using the SiC (silicon carbide) semiconductor element can be optimally operated with the least electrical resistance by supplying a refrigerant adjusted to -100 ° C to 0 ° C. Furthermore, by surrounding the non-contact power feeding means with an electromagnetic shielding material, it is possible to prevent the magnetic field generated by the inductive power feeding from adversely affecting surrounding electronic devices and various communication devices.

  In addition, by installing a superconducting motor device for driving an electric vehicle equipped with a fuel cell, existing liquid hydrogen can be used as a refrigerant for cooling the superconducting coil and the converter, and after cooling the superconducting coil and the converter. By supplying the vaporized hydrogen gas to the fuel cell, it is not necessary to separately provide a vaporization device.

Embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the superconducting motor device 10 of the present embodiment is used for driving an electric vehicle equipped with a fuel cell that generates electricity by reacting hydrogen and oxygen, and is mounted as a supply source of the hydrogen. The ultra-low temperature liquid hydrogen (boiling point: about −252.8 ° C.) is also used as a refrigerant for cooling the superconducting coil 15 of the superconducting motor device 10 and the converter.

The superconducting motor device 10 has a plurality of armature coils 14 fixed to a stator 11 serving as a housing at intervals in the circumferential direction, and is fixed to a rotary drive shaft 20 provided in the stator 11 via a bearing 21. The rotor 12 is provided with a field superconducting coil 15.
As means for supplying power from the external power supply control unit 30 to the superconducting coil 15 of the rotor 12, non-contact power supply means 16 for supplying power by electromagnetic induction in the space between the stator 11 and the rotor 12 is provided. The non-contact power supply means 16 includes an induction power transmission unit 17 attached to the stator 11 side and an induction power reception unit 18 attached to the rotor 12 side.
Since the current received by the induction feeding receiver 18 is alternating current, a converter 19 using a silicon carbide (SiC) semiconductor element is interposed between the induction feeding receiver 18 and the superconducting coil 15 on the rotor 12 side. The alternating current is converted to direct current to supply power to the superconducting coil 15.

The superconducting coil 15 is installed inside a cooling space 23 in which the refrigerant introduction path 22 and the refrigerant outlet path 24 communicate with each other. Liquid hydrogen in an on-vehicle liquid hydrogen tank 27 is supplied to the refrigerant introduction path 22 via a pump 28, and hydrogen gas that has been heated and evaporated by heat exchange with the superconducting coil 15 is discharged to the refrigerant lead-out path 24. Is done.
The refrigerant outlet path 24 communicates with the converter 19 via the temperature control unit 25, and is a temperature at which a silicon carbide semiconductor element of the converter 19 described later operates optimally in the temperature control unit 25. The temperature of the hydrogen gas is controlled to 0 ° C. to 0 ° C. and then supplied to the converter 19 and cooled.

The hydrogen gas that has cooled the converter 19 passes through the refrigerant discharge path 26 that connects the converter 19 and the external fuel cell 29, and is supplied to the fuel cell 29 for power generation.
In the rotor 12, a heat insulating layer is provided so as to isolate the cooling space 23 containing the superconducting coil 15 from the temperature control unit 25, the converter 19, and the induction power receiving unit 18.
The outer surface of the stator 11 is surrounded by an electromagnetic shielding material 31 and shielded so that not only the magnetic field generated by the non-contact power feeding means 16 but also the magnetic field generated by the superconducting coil 23 and the armature coil 14 does not leak to the outside. In this way, the surrounding electronic devices and various communication devices are not adversely affected.

  The electric power generated by the fuel cell 29 is connected by electric wires so as to be supplied to the electric power supply control unit 30. The power supply control unit 30 receives power supplied from the fuel cell 29 via the electric wires as input, and outputs power supplied to the induction power transmission unit 17 and each armature coil 14 via the electric wires. The output timing and voltage are electronically controlled.

Next, the rotation principle of the superconducting motor device 10 will be described.
By supplying power to the superconducting coil 15 from the power supply control unit 30 via the non-contact power feeding means 16 and the converter 19, the rotor 12 becomes an electromagnet having N and S poles as shown in FIG. In the power supply control unit 30, current is sequentially supplied to the four armature coils 14 arranged at intervals in the circumferential direction on the stator 11 side in the order of S 1 → S 2 → S 3 → S 4 → S 1. As a result, a rotating magnetic field is generated. The rotating magnetic field pulls the rotor 12 that is an electromagnet and rotates it synchronously to drive the rotary drive shaft 20. And the torque of the rotational drive shaft 20 is transmitted as rotational power of the wheels of the electric vehicle.

  In this embodiment, four armature coils 14 are provided, but three armature coils 14 may be provided in the circumferential direction to generate a rotating magnetic field by supplying a three-phase alternating current to each armature coil. Further, although the bismuth superconducting wire is used for the superconducting coil 15, a ceramic material such as yttrium, thallium, or bismuth oxide may be used. In this embodiment, liquid hydrogen is used as the refrigerant, but liquid nitrogen may be used.

Hereinafter, an experimental example showing the correlation between the resistivity and the temperature related to the silicon carbide semiconductor element used in the converter 19 will be described with reference to FIGS. 3 and 4.
As shown in FIG. 3, the experimental apparatus has a silicon carbide semiconductor element 42 placed on the upper surface of the refrigerant passage 41 and a thermocouple 43 in contact with the silicon carbide semiconductor element 42. The inside is evacuated by covering.

The silicon carbide semiconductor element 42 uses a semiconductor substrate made of an n-type semiconductor in which nitrogen ions are doped at 10 ¹³ to 10 ¹⁷ per cm ³ in the 4H—SiC type silicon carbide semiconductor element 42. DC1V is applied to the silicon carbide semiconductor element 22 to measure the current, and the relationship between temperature and resistivity is examined. According to the experimental results shown in FIG. 4, the resistivity toward -130 ° C. from 50 ° C. is as low as 10 ^-1 or less, about - it can be seen that most resistivity decreased at 60 ° C. vicinity. That is, in consideration of cooling the silicon carbide semiconductor element using a cryogenic refrigerant, the silicon carbide semiconductor element can be effectively operated by setting the ambient temperature in the range of 0 ° C. to −100 ° C. it can.

Therefore, in the superconducting motor device 10 described above, the hydrogen gas that is vaporized by cooling the superconducting coil 15 in the cooling space 23 and discharged to the refrigerant lead-out path 24 is brought to 0 ° C. to −100 ° C. by the temperature control unit 25. By sending the temperature to the converter 19 after adjusting the temperature, the converter 19 can be operated efficiently.
Further, by diverting the heated hydrogen gas after cooling the superconducting coil 15 as a cooling refrigerant for the converter 19, it is not necessary to provide another cooling means exclusively for the converter 19. The converter 19, which may have a high cooling temperature, can be cooled efficiently and at low cost.

It is a schematic sectional drawing of the superconducting motor apparatus of embodiment of this invention. It is explanatory drawing which shows the operation principle of a superconducting motor apparatus. It is the schematic of the experimental apparatus which investigates the resistivity and temperature of a silicon carbide semiconductor element. It is a graph which shows the relationship between the resistivity of a silicon carbide semiconductor element, and temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Superconducting motor apparatus 11 Stator 12 Rotor 13 Heat insulation layer 14 Armature coil 15 Superconducting coil 16 Non-contact electric power feeding means 17 Inductive electric power transmission part 18 Inductive electric power receiving part 19 Converter 20 Rotation drive shaft 21 Bearing 22 Refrigerant introduction part 23 Cooling space 24 Refrigerant outlet passage 25 Temperature control unit 26 Refrigerant discharge passage 27 Liquid hydrogen tank 28 Pump 29 Fuel cell 30 Electric power supply controller

Claims (9)

A non-contact power feeding means for performing inductive power feeding between the rotor and the stator is provided, and a converter for converting alternating current to direct current and a superconducting coil are fixed to the rotor. A superconducting motor device that converts alternating current received on the rotor side into direct current by the converter and supplies power to the superconducting coil,
The superconducting coil is disposed in a cooling space in the rotor, and a refrigerant introduction path through which a refrigerant is supplied from the outside to the cooling space, and a refrigerant from which the refrigerant whose temperature has been raised by heat exchange with the superconducting coil is discharged. A superconducting motor device, characterized in that a lead-out path is provided and the converter is cooled by the refrigerant whose temperature has risen in the refrigerant lead-out path. The superconducting coil fixed to the rotor is for field use, and a plurality of armature coils are fixed to the stator side at intervals in the circumferential direction.
2. The rotor according to claim 1, wherein the rotor side is electromagnetized by feeding and exciting the superconducting coil, and the rotor is rotated by generating a rotating magnetic field by sequentially feeding each of the plurality of armature coils. The superconducting motor device described.   The superconducting motor device according to claim 1, wherein a temperature control unit for adjusting the temperature of the refrigerant heated by heat exchange with the superconducting coil to a specific temperature is interposed in the refrigerant outlet path.   The superconducting motor device according to any one of claims 1 to 3, wherein the converter uses a silicon carbide (SiC) semiconductor element.   The superconducting motor device according to claim 3 or 4, wherein the temperature of the refrigerant supplied from the refrigerant outlet path to the converter is adjusted to -100 ° C to 0 ° C by the temperature control unit.   The superconducting motor device according to any one of claims 1 to 5, wherein the non-contact power feeding means is surrounded by an electromagnetic shielding material.   The superconducting motor device according to claim 6, wherein the electromagnetic shielding material covers an outer surface of the stator.   The superconducting motor device according to any one of claims 1 to 7, wherein the refrigerant is liquid hydrogen or liquid nitrogen. It is mounted on an electric vehicle that generates electricity by reacting hydrogen stored in a liquid hydrogen tank with oxygen by a fuel cell,
Liquid hydrogen in the liquid hydrogen tank is used as the refrigerant, and hydrogen gas evaporated through the refrigerant introduction path, the refrigerant space, the refrigerant outlet path, and the converter is supplied to the fuel cell for power generation. The superconducting motor device according to any one of claims 1 to 8, wherein the electric power is supplied to the superconducting coil and the armature coil.

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