JP4869846B2 - Power conversion element - Google Patents

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JP4869846B2
JP4869846B2 JP2006252715A JP2006252715A JP4869846B2 JP 4869846 B2 JP4869846 B2 JP 4869846B2 JP 2006252715 A JP2006252715 A JP 2006252715A JP 2006252715 A JP2006252715 A JP 2006252715A JP 4869846 B2 JP4869846 B2 JP 4869846B2
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thermoelectric conversion
conversion element
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temperature
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芳生 平野
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Nippon Steel Corp
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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Description

本発明は、電力を所望の電圧、電流、周波数に変換する電力変換装置(素子)に関するものである。   The present invention relates to a power conversion device (element) that converts electric power into desired voltage, current, and frequency.

熱電変換材料は、熱エネルギを電力にする機能(ゼーベック効果)、又は、電力を供給することにより物体を冷却する機能(ペルチェ効果)を有する。これらの材料は、一般には熱電変換材料であるP型、N型の極性を有した半導体を金属等の導体からなる電極でつないで素子を構成し、片側を加熱し、もう片側を冷却して温度差を与えると、熱起電力を生じさせることができる(ゼーベック効果)。また、反対にこれら素子に電流を流すと片側で発熱が、もう片側で吸熱が生じる事が知られている(ペルチェ効果)。熱電変換材料として、具体的にはビスマステルル系、鉛テルル系、シリコン・ゲルマニウム系やコバルト-アンチモン、ランタン-アンチモン等の元素で構成されたスクッテルダイト構造を持つ熱電変換材料等を挙げることができる。例えば、ビスマステルル系は熱電変換素子として利用可能な温度は500K程度とされ、鉛テルル系は800Kまでの高温度域で利用可能である。また、理想状態の熱電変換素子で発電を行う場合の電気出力は(式1)で表される(非特許文献1)。
Pj=(α2/ρ)(S0/L0)(ΔT2/2) ・・・・ (式1)
ここで、Pj:電気出力(W)、α:熱電変換素子1対当たりのゼーベック係数(VK-1)、S0:熱電素子の断面積(m2)、L0:熱電素子の足の長さ(m)、ΔT:熱電素子の接合部温度勾配(K)である。
The thermoelectric conversion material has a function of converting thermal energy into electric power (Seebeck effect) or a function of cooling an object by supplying electric power (Peltier effect). These materials are generally composed of P-type and N-type semiconductors, which are thermoelectric conversion materials, connected to electrodes made of conductors such as metals to form elements, and heat one side and cool the other side. When a temperature difference is given, a thermoelectromotive force can be generated (Seebeck effect). On the other hand, it is known that when current is passed through these elements, heat is generated on one side and heat is absorbed on the other side (Peltier effect). Specific examples of thermoelectric conversion materials include bismuth tellurium-based, lead tellurium-based, silicon-germanium-based, thermoelectric conversion materials having a skutterudite structure composed of elements such as cobalt-antimony and lanthanum-antimony. it can. For example, bismuth tellurium can be used as a thermoelectric conversion element at a temperature of about 500K, and lead tellurium can be used in a high temperature range up to 800K. Further, the electrical output when power is generated by the thermoelectric conversion element in the ideal state is expressed by (Equation 1) (Non-patent Document 1).
Pj = (α 2 / ρ) (S 0 / L 0) (ΔT 2/2) ···· ( Equation 1)
Where, Pj: electrical output (W), α: Seebeck coefficient per thermoelectric conversion element pair (VK -1 ), S 0 : cross section area of thermoelectric element (m 2 ), L 0 : thermoelectric element leg length (M), ΔT: temperature gradient (K) at the junction of the thermoelectric element.

(式1)から明らかなように、熱電変換素子の発電出力は、熱電変換素子の温度勾配の自乗で大きくできることがわかる。従って、ゼーベック効果により発電を行う場合、熱源としては高温な物体に接続することが望ましいことが知られている。
これらの熱電変換素子は、例えば、ゼーベック効果を利用して自動車の廃熱で発電する等の応用や、ペルチェ効果を利用した冷蔵庫が成されている(非特許文献1)。
As is clear from (Formula 1), it can be seen that the power generation output of the thermoelectric conversion element can be increased by the square of the temperature gradient of the thermoelectric conversion element. Therefore, it is known that when generating electricity by the Seebeck effect, it is desirable to connect to a high-temperature object as a heat source.
These thermoelectric conversion elements are, for example, applications such as power generation using waste heat from automobiles using the Seebeck effect, and refrigerators using the Peltier effect (Non-patent Document 1).

一方、半導体材料としては、シリコン半導体材料をベースとした素子が広範囲で用いられている。シリコン半導体は、CPUやメモリ、発信器等のデジタル素子用の材料として用いられており、さらには、交流の100V電圧を5V等の所望の直流電圧に変換する電源機器や、携帯電話等の基地局で信号を増幅するアンプ等のアナログ素子として用いられる等、デジタル機器、アナログ機器等、広範囲に用いられている。また、小型化、高出力化を目指し、多くの分野でその電力素子の動作速度が高周波化されつつある。これらのシリコン電力素子は、シリコン材料の物性値(真性半導体温度)から使用温度に限界があり、例えば、一般の電力用パワー素子では素子内部の温度で150℃程度を上限として、これを超えないように回路設計している(非特許文献2)。   On the other hand, elements based on silicon semiconductor materials are widely used as semiconductor materials. Silicon semiconductors are used as materials for digital elements such as CPUs, memories, and transmitters. In addition, power supply equipment that converts AC 100V voltage to desired DC voltage such as 5V, and bases such as mobile phones It is used in a wide range of digital equipment, analog equipment, etc., such as being used as an analog element such as an amplifier that amplifies a signal in a station. In addition, with the aim of miniaturization and higher output, the operating speed of the power element is increasing in many fields. These silicon power devices have a limit in the operating temperature due to the physical property value (intrinsic semiconductor temperature) of the silicon material. For example, in a general power device for power, the temperature inside the device is limited to about 150 ° C. and does not exceed this. The circuit is designed as described above (Non-patent Document 2).

以上の熱電変換素子と半導体素子とを組み合わせて、冷却や発電を試みる例がこれまでに検討がなされてきた。
特許文献1では、半導体素子と熱電変換材料を組み合わせて、半導体素子から発生する熱に対して、ペルチェ効果を用いて熱を放出する例が記載されている。
また、特許文献2では、小型機器等から発熱する熱を利用して、ゼーベック効果により、電力を発電することが記載されている。
熱電変換システム技術総覧 3〜15、25〜32、53〜61、148〜152、252〜279頁 平成16年7月31日発行 リアライズ理工センター発行 実用電源回路設計ハンドブック 65頁 1988年5月20日初版 CQ出版社株式会社 特開平2-143548号公報 特開2005-347348号公報
The example which tried cooling and electric power generation combining the above thermoelectric conversion element and a semiconductor element has been examined until now.
Patent Document 1 describes an example in which a semiconductor element and a thermoelectric conversion material are combined to release heat using the Peltier effect with respect to heat generated from the semiconductor element.
Patent Document 2 describes that electric power is generated by the Seebeck effect using heat generated from a small device or the like.
Thermoelectric conversion system technology overview 3-15, 25-32, 53-61, 148-152, 252-279, issued July 31, 2004 Realized Science and Technology Center Practical power supply circuit design handbook 65 pages May 20, 1988 First edition CQ Publishing Co., Ltd. JP-A-2-143548 JP 2005-347348 A

シリコン半導体素子は、シリコンの物性から、素子として動作可能な温度は限界を持っていた。実際、一般のパワー系の半導体素子においては安全余裕を持たせて、実用上、素子内部で150℃までを使用限界としている。   The silicon semiconductor device has a limit on the temperature at which it can operate as a device due to the physical properties of silicon. In fact, a general power semiconductor device has a safety margin and practically has a use limit of 150 ° C. inside the device.

これらシリコン半導体素子と熱電変換素子とを組み合わせて、シリコン半導体素子の損失により生じる熱を熱源として、熱電変換素子により発電させようとする際、空冷の場合には、熱電変換素子部位に形成でいる温度勾配は室温とシリコン素子の利用限界温度である150℃の間が最大となる。発電効率を増すため、例えばシリコン素子の通電電力量を高く設計して、より大きな温度勾配をつけようとすると、当然、シリコン素子の許容温度を超えて破壊に至る問題が生じ、大きな出力電力を得ることが困難であった。また、低温端の温度を下げて温度勾配をつけるために、水冷を試みることも可能であるが、空冷に比べて、システムの信頼性が下がるという問題があった。   When these silicon semiconductor elements and thermoelectric conversion elements are combined and heat generated by the loss of the silicon semiconductor elements is used as a heat source to generate power by the thermoelectric conversion elements, they are formed at the thermoelectric conversion element portions in the case of air cooling. The temperature gradient is maximum between room temperature and 150 ° C., which is the limit temperature for using silicon devices. In order to increase the power generation efficiency, for example, if the energization power amount of the silicon element is designed to be high and an attempt is made to create a larger temperature gradient, naturally, there will be a problem of exceeding the allowable temperature of the silicon element and causing a breakdown. It was difficult to get. Although it is possible to try water cooling to lower the temperature at the low temperature end to create a temperature gradient, there is a problem that the reliability of the system is lower than that of air cooling.

また、熱電変換素子を半導体素子に装着する場合には、一般に冷却フィンと半導体素子の間に配置される。放熱の熱抵抗は、熱放散経路の距離に比例するため、半導体素子から見れば熱電変換素子の存在は放熱のための1種の熱抵抗ともなり、熱放散設計も複雑となり、電力変換素子としての信頼性も低下する等の問題が生じていた。   In addition, when the thermoelectric conversion element is mounted on a semiconductor element, the thermoelectric conversion element is generally disposed between the cooling fin and the semiconductor element. Since the thermal resistance of heat dissipation is proportional to the distance of the heat dissipation path, the presence of the thermoelectric conversion element is also a kind of thermal resistance for heat dissipation from the viewpoint of the semiconductor element, the heat dissipation design becomes complicated, and as a power conversion element There has been a problem such as a decrease in reliability.

本発明は、以上の課題を解決するため、炭化珪素、ガリウム砒素、窒化ガリウム、ダイヤモンド、またはこれらを複合した材料であって150℃以上の温度でも動作する半導体材料と、熱電変換材料とを、熱伝導率が1.0W/m・K以上の電気絶縁材料を介して熱伝導可能に対向させて一体とし、半導体材料からの発熱を利用して熱電変換材料により発電することができ、また、熱電変換材料に通電して半導体材料を冷却できることを特徴する電力変換素子をその手段として提供する。 In order to solve the above problems, the present invention provides a silicon carbide, gallium arsenide, gallium nitride, diamond, or a composite material of these materials and a semiconductor material that operates even at a temperature of 150 ° C. or higher, and a thermoelectric conversion material . The heat conductivity is 1.0 W / m · K or more and they are made to oppose each other so as to be able to conduct heat through an electrically insulating material, and heat can be generated by the thermoelectric conversion material using heat generated from the semiconductor material. The power conversion element characterized in that the semiconductor material can be cooled by energizing the conversion material is provided as the means.

その電力変換素子の半導体材料は、炭化珪素、ガリウム砒素、窒化ガリウム、ダイヤモンドあるいはこれらの複合体であることが望ましい。また、半導体材料と熱電変換材料は、熱伝導性の良い電気絶縁材料を介して接合してあることが望ましい。さらに、半導体材料の動作可能温度範囲内で、半導体材料から発生する熱を熱源とし、熱電変換素子により発電を行うのがよく、また半導体材料の設定動作温度上限を超えた場合に、熱電変換材料へ通電を行い、半導体材料を冷却する機能を有するようにするのがよい。更には、それら電力変換素子は20KHz以上の高い周波数で電力変換が行われるのがよい。   The semiconductor material of the power conversion element is preferably silicon carbide, gallium arsenide, gallium nitride, diamond, or a composite thereof. Moreover, it is desirable that the semiconductor material and the thermoelectric conversion material are bonded via an electrically insulating material having good thermal conductivity. Furthermore, within the operable temperature range of the semiconductor material, heat generated from the semiconductor material is used as a heat source, and it is preferable to generate power by a thermoelectric conversion element, and when the upper limit of the set operating temperature of the semiconductor material is exceeded, the thermoelectric conversion material It is preferable that the semiconductor material has a function of cooling the semiconductor material. Furthermore, these power conversion elements are preferably subjected to power conversion at a high frequency of 20 KHz or higher.

また、その半導体材料として、真性半導体温度が高く、物性的に高温での動作が可能でかつ半導体材料としてシリコンより高い飽和ドリフト速度、及び絶縁破壊電界を持つことが判明している炭化珪素(SiC)、ガリウム砒素(GaAs)、窒化ガリウム(GaN)、ダイヤモンド、またはこれらを複合した材料を用いることにより、電力変換用としてより一層優れた素子を構成でき、かつ素子の廃熱を用いて発電する機能を有するため、その電力をさらに有効活用すれば、素子全体として高効率な電力変換素子を形成することができる。   As its semiconductor material, silicon carbide (SiC), which has been found to have a high intrinsic semiconductor temperature, can be operated at high physical properties, and has a higher saturation drift velocity and dielectric breakdown electric field than silicon as a semiconductor material. ), Gallium arsenide (GaAs), gallium nitride (GaN), diamond, or a composite material of these materials, it is possible to construct a more excellent device for power conversion and to generate power using the waste heat of the device. Since it has a function, if the electric power is further effectively used, a highly efficient power conversion element can be formed as the entire element.

具体的には、真性半導体温度Ti及び飽和ドリフト速度Vs、絶縁破壊電界EBは、シリコンではTi=600K、Vs=1×107cm/s、EB=0.3MV/cmであるのに対して、SiCは4HポリタイプでTi=1400K、Vs=2.7×107cm/s、EB=3.5MV/cm、同じく6HポリタイプでTi=1300K、Vs=2.0×107cm/s、EB=3.0MV/cm、3CポリタイプでTi=1000K、Vs=2.7×107cm/s、EB=3.0MV/cmであり、GaAsはTi=850K、Vs=2.0×107cm/s、EB=0.65MV/cmであり、GaNはTi=2000K、EB=2.6MV/cm、Vs=2.7×107cm/s、ダイヤモンドはTi=3000K、Vs=2.7×107cm/s、EB=5.6MV/cmである。尚、真性半導体温度は、真性キャリア濃度が5×1015cm-3になる温度である。
前述した真性半導体温度は物性限界であり、実際に工業利用としてはその温度以下で、十分な余裕を持った設計温度で素子は製造される。例えば、SiCでは、凡そ700℃(943K)以下で設計するのが実用的である。
Specifically, the intrinsic semiconductor temperature Ti and saturated drift velocity Vs, the breakdown electric field E B is a silicon Ti = 600K, Vs = 1 × 10 7 cm / s, is whereas the E B = 0.3MV / cm SiC is 4H polytype, Ti = 1400K, Vs = 2.7 × 10 7 cm / s, E B = 3.5MV / cm, 6H polytype is Ti = 1300K, Vs = 2.0 × 10 7 cm / s, E B = 3.0MV / cm, 3C polytype, Ti = 1000K, Vs = 2.7 × 10 7 cm / s, E B = 3.0MV / cm, GaAs is Ti = 850K, Vs = 2.0 × 10 7 cm / s E B = 0.65 MV / cm, GaN is Ti = 2000K, E B = 2.6 MV / cm, Vs = 2.7 × 10 7 cm / s, diamond is Ti = 3000K, Vs = 2.7 × 10 7 cm / s E B = 5.6 MV / cm. The intrinsic semiconductor temperature is a temperature at which the intrinsic carrier concentration becomes 5 × 10 15 cm −3 .
The intrinsic semiconductor temperature described above is a physical property limit, and the element is actually manufactured at a design temperature with a sufficient margin below that temperature for industrial use. For example, in SiC, it is practical to design at about 700 ° C. (943K) or less.

また、これら電力変換素子は、例えば、電力系統に流れるノイズ等が原因して設計以上に半導体材料が発熱し、熱暴走を起こして、素子の使用設定温度の上限を超えた場合には、発電に用いていた熱電変換素子に逆に電流を外部から流して冷却し、設定温度以下にすることも可能であり、電力変換素子として高い信頼性を有することができる。   In addition, these power conversion elements generate power when the semiconductor material generates heat more than designed due to noise flowing in the power system, causing thermal runaway and exceeding the upper limit of the set operating temperature of the element. On the other hand, it is possible to cool the thermoelectric conversion element used in the above by flowing an electric current from the outside to a temperature lower than the set temperature, and the power conversion element can have high reliability.

また、電力変換における周波数は、一般には可聴周波数の上限以上である20KHz以上の高周波域で動作させると、人間の耳に電子部品から発生する音のノイズは低減できるとされるが、半導体素子の損失は増大する。本発明の電力変換素子において20KHzで動作させると、半導体素子温度は一般に変換周波数の自乗に比例して上昇するため、温度勾配を高めることができ、さらに高速な電子移動度の半導体材料を用いているため、半導体損失量は少なくでき、高効率化が可能である。加えて、その高周波動作により、本発明の電力変換素子を搭載した電源等の回路部品も小型化でき、システム全体も小型化が可能である。   In addition, the frequency of power conversion is generally considered to be reduced when noise is generated from electronic components in human ears when operated in a high frequency range of 20 KHz or higher, which is higher than the upper limit of the audible frequency. Loss increases. When the power conversion element of the present invention is operated at 20 KHz, the temperature of the semiconductor element generally increases in proportion to the square of the conversion frequency, so that the temperature gradient can be increased, and a semiconductor material having a higher electron mobility can be used. Therefore, the amount of semiconductor loss can be reduced and high efficiency can be achieved. In addition, the high-frequency operation can reduce the size of circuit components such as a power supply equipped with the power conversion element of the present invention, and the entire system can be reduced in size.

本発明によれば、シリコン半導体では動作させるのが困難な150℃以上で動作する半導体材料で構成された半導体素子と熱電変換材料で構成された素子とを組み合わせて、半導体材料が高い温度で発熱するように動作時の通電電力量、周波数等を設定すれば、熱電変換素子に対して大きな温度勾配を形成することができ、熱電変換素子の発電電力量を効率的に高めることができる。   According to the present invention, a combination of a semiconductor element made of a semiconductor material that operates at 150 ° C. or more, which is difficult to operate with a silicon semiconductor, and an element made of a thermoelectric conversion material, the semiconductor material generates heat at a high temperature. If the energization power amount, frequency, etc. during operation are set as described above, a large temperature gradient can be formed with respect to the thermoelectric conversion element, and the power generation amount of the thermoelectric conversion element can be increased efficiently.

図1は、本発明の第1の実施形態による電力変換素子の構成図である。1は150℃以上の温度で動作可能な半導体材料であるSiC材料を用いて製造した半導体素子(PN型ダイオード)であり、素子内部で250℃、素子表面で220℃の使用温度限界を持ち、最大定格電圧600V、最大定格電流5A、樹脂モールドされたディスクリート構成の素子であって、背面には非絶縁の放熱金属板が露出した構造であり、かつ、ダイオード端子2を備えてなる。3はビスマス・テルル系材料からなる熱電変換素子であり、素子サイズは10mm角、300℃までの使用温度限界を持ち、熱電変換素子端子3を備える。   FIG. 1 is a configuration diagram of a power conversion element according to the first embodiment of the present invention. 1 is a semiconductor element (PN type diode) manufactured using SiC material, which is a semiconductor material that can operate at a temperature of 150 ° C or higher, and has a working temperature limit of 250 ° C inside the element and 220 ° C on the element surface, The element is a discrete component molded with resin, which has a maximum rated voltage of 600 V, a maximum rated current of 5 A, and has a structure in which a non-insulating heat radiating metal plate is exposed on the back surface, and a diode terminal 2 is provided. 3 is a thermoelectric conversion element made of a bismuth-tellurium-based material. The element size is 10 mm square, has a use temperature limit of up to 300 ° C., and has a thermoelectric conversion element terminal 3.

半導体素子1と熱電変換素子3との間には電気絶縁性を持ち、1.0W/m・Kの高熱伝導率を有したシリコン樹脂製のシート5を10mm角に切って配置した。また、熱電変換素子3の片側には、アルミ製の放熱フィン6(外形40mm×20mm×20mm)を配置し、ダイオードとシリコン樹脂絶縁シート、及び熱電変換素子をねじ穴付きの金属製のバンド7で束ねて一体として組み合わせ、放熱フィンにねじで取り付けた。   Between the semiconductor element 1 and the thermoelectric conversion element 3, a sheet 5 made of silicon resin having electrical insulation and having a high thermal conductivity of 1.0 W / m · K was cut into a 10 mm square. Also, on one side of the thermoelectric conversion element 3, aluminum radiating fins 6 (outer dimensions 40 mm × 20 mm × 20 mm) are arranged, and the diode and silicon resin insulation sheet, and the thermoelectric conversion element are made of metal bands 7 with screw holes. And bundled together as a unit, and attached to the heat radiating fins with screws.

本発明の有効性を検証するため、図2に示すような昇圧チッパー回路を別途構成し、実際に動作させてみた。9は直流電圧源、10はチョークインダクター、11はMOSFET、12はダイオード、13は出力コンデンサ、14は負荷抵抗、15は11のMOSFETを動作させるためにFETのゲート電圧に電圧を与える高周波電圧発生回路である。   In order to verify the effectiveness of the present invention, a booster chipper circuit as shown in FIG. 2 was separately constructed and actually operated. 9 is a DC voltage source, 10 is a choke inductor, 11 is a MOSFET, 12 is a diode, 13 is an output capacitor, 14 is a load resistor, and 15 is a high frequency voltage that applies a voltage to the gate voltage of the FET to operate the 11 MOSFET It is a generation circuit.

図1で示した本発明の電力変換素子のダイオード端子2を図2の回路の12に接続配置して実験を行った。入力電圧は240V、出力電圧は300V、MOSFETの動作周波数は100KHzとして、14の付加抵抗及びMOSFETのゲートON電圧時間を調整しながら電力変換を行い、ダイオード12に流れる平均電流を1Aに調整した。このとき、予めSiCからなるダイオード表面に配置した温度センサーの指示温度は190℃であった。同じく放熱フィンと熱電素子の近くに配した温度センサーの指示温度は90℃であった。この状態で熱電変換素子の端子電極(熱電変換素子端子4)に電力測定器を取り付けて、発電電力量を測定したところ、60mWの電力が発生していることが確認された。   An experiment was conducted by connecting the diode terminal 2 of the power conversion element of the present invention shown in FIG. 1 to the circuit 12 of FIG. The input voltage was 240V, the output voltage was 300V, the MOSFET operating frequency was 100KHz, power conversion was performed while adjusting the 14 additional resistors and MOSFET gate ON voltage time, and the average current flowing through the diode 12 was adjusted to 1A. At this time, the indicated temperature of the temperature sensor previously arranged on the surface of the diode made of SiC was 190 ° C. Similarly, the indicated temperature of the temperature sensor placed near the heat dissipating fin and the thermoelectric element was 90 ° C. In this state, a power measuring device was attached to the terminal electrode (thermoelectric conversion element terminal 4) of the thermoelectric conversion element, and when the amount of generated power was measured, it was confirmed that 60 mW of power was generated.

この状態でさらに周波数を120KHzに上昇させたところ、SiCダイオード素子1の温度は210℃となった。このとき、熱電変換素子に外部電源をつないで、直流電流を流したところ、SiCダイオード素子1の温度が190℃に下がった。   In this state, when the frequency was further increased to 120 KHz, the temperature of the SiC diode element 1 was 210 ° C. At this time, when an external power source was connected to the thermoelectric conversion element and a direct current was passed, the temperature of the SiC diode element 1 decreased to 190 ° C.

また、比較のため、図1の1のダイオード素子を限界使用温度が素子内部で150℃、素子表面で120℃のシリコン半導体からなるダイオードに取り替えて、同じく評価回路(図2)を用いて測定を行った。先の実験と同じ条件では、シリコンダイオードが限界温度を超えて破損するため、動作周波数を下げて、15KHz動作とした。周波数を下げても連続的に直流電流を維持するには、チョークインダクターのインダクタンス値を上げる必要があることから、図2の10のチョークインダクターを、約3倍の断面積を持つ大型の物に変更し、インダクタンス値を5倍にした。その他の条件は先述した実験と同様として実験した。この結果、予めシリコン材料からなるダイオード表面に配置した温度センサーの指示温度は120℃であった。同じく放熱フィンと熱電素子の近くに配した温度センサーの指示温度は70℃であった。この状態で熱電変換素子の端子電極に測定器を取り付けて、発電電力量を測定したところ、35mWの電力が発生していることが確認された。また、周波数を下げたため、SiCダイオードでは聞こえなかった、高周波の音がインダクター近傍から聞こえてきた。   For comparison, the diode element in Fig. 1 was replaced with a diode made of a silicon semiconductor with a limit operating temperature of 150 ° C inside the element and 120 ° C on the element surface, and measured using the same evaluation circuit (Figure 2). Went. Under the same conditions as the previous experiment, the silicon diode was damaged beyond the limit temperature, so the operating frequency was lowered to 15KHz operation. In order to maintain DC current continuously even if the frequency is lowered, it is necessary to increase the inductance value of the choke inductor. Therefore, the 10 choke inductors in Fig. 2 are I changed it to a thing and increased the inductance value 5 times. The other conditions were the same as those described above. As a result, the indicated temperature of the temperature sensor previously arranged on the surface of the diode made of silicon material was 120 ° C. Similarly, the indicated temperature of the temperature sensor placed near the heat dissipating fin and the thermoelectric element was 70 ° C. In this state, a measuring instrument was attached to the terminal electrode of the thermoelectric conversion element, and the amount of generated power was measured, and it was confirmed that 35 mW of power was generated. Also, because the frequency was lowered, high-frequency sounds that could not be heard with SiC diodes were heard from the vicinity of the inductor.

以上の実験により、本発明の電力変換素子の構成では、シリコン素子と組み合わせた場合以上の高い発電電力を得ることができ、かつ、同じ電力を扱うにも、高周波で動作させることができたため、チョークインダクターの断面積が1/3で済み静音性がある等、回路を構成する電子部品の小型化にも寄与することが確認された。   From the above experiment, in the configuration of the power conversion element of the present invention, it was possible to obtain a higher generated power than when combined with a silicon element, and it was possible to operate at the high frequency to handle the same power, It has been confirmed that it contributes to the miniaturization of the electronic components that make up the circuit.

図3は、本発明の第2の実施形態を示す、電力変換素子の断面図である。第1の実施例では150℃以上の温度で動作する半導体素子と熱電変換素子とはそれぞれ別個に製作したものを組み合わせて一体としたが、図3ではチップレベルで一体としたものである。
16はSiC基板、17はGaNのエピ層、18はショットキー電極、19はオーミック電極、20は熱伝導率が30W/m・Kのアルミナ、21は熱電変換素子、22は同じく熱伝導率が30W/m・Kのアルミナ、23は放熱用の銅金属である。16のSiC基板と17のGaN層からなる部分は、ショットキー電極18及びオーミック電極19でショットキーダイオードを形成しており、ショットキー電極とGaN層の面積は2mm角チップとした。また、SiC基板は、熱放散効果を高めるため、広い面積とし、10mm角とした。同じく熱電変換素子も10mm角のサイズとした。本断面を持つチップに、ボンディングワイヤー等で外部銅電極を接合した後、樹脂モールドし、ディスクリート素子を形成した。なお、熱電変換素子の外側に接合した放熱用の銅金属23は、後ほど取り付ける放熱フィンとの熱伝導性を高めるため、むき出しとし、樹脂には埋め込まなかった。また、本素子の使用限界温度を測定したところ、内部で240℃、素子表面で210℃であった。
FIG. 3 is a cross-sectional view of a power conversion element showing a second embodiment of the present invention. In the first embodiment, the semiconductor element operating at a temperature of 150 ° C. or higher and the thermoelectric conversion element are combined and integrated separately, but in FIG. 3, they are integrated at the chip level.
16 is a SiC substrate, 17 is an epitaxial layer of GaN, 18 is a Schottky electrode, 19 is an ohmic electrode, 20 is an alumina with a thermal conductivity of 30 W / mK, 21 is a thermoelectric conversion element, and 22 has the same thermal conductivity. 30W / m · K alumina, 23 is copper metal for heat dissipation. A part consisting of 16 SiC substrates and 17 GaN layers formed Schottky diodes with Schottky electrodes 18 and ohmic electrodes 19, and the area of the Schottky electrodes and GaN layers was a 2 mm square chip. Also, the SiC substrate has a large area and 10 mm square in order to enhance the heat dissipation effect. Similarly, the thermoelectric conversion element was 10 mm square. After joining an external copper electrode to the chip having this cross section with a bonding wire or the like, resin molding was performed to form a discrete element. Note that the copper metal 23 for heat dissipation bonded to the outside of the thermoelectric conversion element was exposed and not embedded in the resin in order to increase the thermal conductivity with the heat dissipating fins to be attached later. Further, when the use limit temperature of this device was measured, it was 240 ° C. inside and 210 ° C. on the device surface.

以上のようにして構成したデバイスに1.0W/m・Kの高熱伝導率シリコン絶縁シートを介して、図1と同じサイズの放熱フィンに取り付け、同じく図2に示す回路でその効果を評価した。周波数は100KHzとし、そのほかの条件は先述したSiCダイオードの実験と全く同じ条件とした。   The device configured as described above was attached to a heat radiating fin of the same size as in FIG. 1 via a 1.0 W / m · K high thermal conductivity silicon insulating sheet, and the effect was evaluated using the circuit shown in FIG. The frequency was 100 KHz, and other conditions were exactly the same as in the SiC diode experiment described above.

本回路で測定を行ったところ、予めGaNエピ層を有する電力変換素子表面に配置した温度センサーの指示温度は170℃であった。同じく放熱フィンと電力変換素子の近くに配した温度センサーの指示温度は80℃であった。この状態で熱電変換素子の端子電極に測定器を取り付けて、発電電力量を測定したところ、50mWの電力が発生していることが確認された。
さらに、周波数を120KHzに上げたところ、電力変換素子の温度は190℃となった。この状態で熱電変換素子の端子に直流電流を流したところ、電力変換素子の温度が170℃となった。
When this circuit was used for measurement, the indicated temperature of the temperature sensor previously disposed on the surface of the power conversion element having the GaN epi layer was 170 ° C. Similarly, the indicated temperature of the temperature sensor placed near the heat dissipating fin and the power conversion element was 80 ° C. In this state, a measuring instrument was attached to the terminal electrode of the thermoelectric conversion element, and the amount of generated power was measured. As a result, it was confirmed that 50 mW of power was generated.
Furthermore, when the frequency was increased to 120 KHz, the temperature of the power conversion element became 190 ° C. In this state, when a direct current was passed through the terminals of the thermoelectric conversion element, the temperature of the power conversion element became 170 ° C.

以上のように、本発明では、熱電変換素子と半導体素子をそれぞれ個別に形成して一体としても、あるいは、チップレベルで一体化しても同様の効果を得ることができる。また、上述の実施形態では昇圧電源回路で評価したが、本発明の電力変換素子は、降圧電源回路やインバータ回路、GHzで動作する高周波増幅回路でも効果を発揮することができる。   As described above, in the present invention, the same effect can be obtained by forming the thermoelectric conversion element and the semiconductor element individually and integrating them or integrating them at the chip level. In the above-described embodiment, the boost power supply circuit is evaluated. However, the power conversion element of the present invention can also be effective in a step-down power supply circuit, an inverter circuit, and a high-frequency amplifier circuit operating at GHz.

本発明は、バイポーラ、ユニポーラ型いずれのタイプのダイオードでもよく、さらに、MOSFET、MESFET、IGBT、GTO、サイリスタ等の能動部品でも同様な効果を得ることができる。
また、半導体材料も、上記以外のGaAs、ダイヤモンドや上記の材料も含めたこれらの材料の複合体でも、同様な効果を得ることができる。
熱電変換素子も、対象とする素子の発熱温度に合わせて、ビスマステルル系、鉛テルル系、シリコン・ゲルマニウム系を使い分けることができる。さらに、コバルト-アンチモン、ランタン-アンチモン等の元素で構成されたスクッテルダイト構造を持つ熱電変換材料でも同様な効果を得ることができる。
また、電気絶縁に用いる材料として、シリコン絶縁シートやアルミナで実施したが、少なくとも半導体のパッケージに用いられている汎用エポキシ樹脂の熱伝導率である0.19W/m・K以上であり、望ましくは汎用のシリコン絶縁シートの1.0W/m・K以上であって、放熱フィンとして用いられるアルミニウムの熱伝導率236W/m・Kや、銅の熱伝導率390W/m・K程度の熱伝導率を持ったものが良い。
The present invention may be a bipolar or unipolar type diode, and the same effect can be obtained with active components such as MOSFET, MESFET, IGBT, GTO, and thyristor.
Moreover, the same effect can be obtained even if the semiconductor material is a composite of these materials including GaAs, diamond and the above materials other than those described above.
Thermoelectric conversion elements can be selected from bismuth tellurium, lead tellurium, and silicon / germanium, depending on the heat generation temperature of the target element. Furthermore, the same effect can be obtained even with a thermoelectric conversion material having a skutterudite structure composed of elements such as cobalt-antimony and lanthanum-antimony.
The material used for electrical insulation was silicon insulation sheet or alumina, but at least 0.19 W / m · K, which is the thermal conductivity of general-purpose epoxy resin used in semiconductor packages, and preferably general-purpose It is 1.0 W / m · K or more of the silicon insulating sheet of aluminum, and has a thermal conductivity of 236 W / m · K for aluminum used as a heat dissipation fin and 390 W / m · K for copper. Good thing.

本発明に係る電力変換素子の第1実施形態を示す概略図及び断面図BRIEF DESCRIPTION OF THE DRAWINGS Schematic and sectional view showing a first embodiment of a power conversion element according to the present invention 電力変換素子を評価するための評価回路概略図Schematic diagram of evaluation circuit for evaluating power conversion elements 本発明に係る電力変換素子の第2実施形態を示す概略図Schematic which shows 2nd Embodiment of the power converter device which concerns on this invention

符号の説明Explanation of symbols

1 SiCダイオード素子
2 ダイオード端子
3 熱電変換素子
4 熱電変換素子端子
5 高熱伝導絶縁材
6 放熱フィン
7 バンド
8 フィン留め金
9 直流電圧源
10 チョークインダクター
11 MOSFET
12 ダイオード
13 出力コンデンサ
14 負荷抵抗
15 高周波電圧発生回路
16 SiC基板
17 GaNエピ層
18 ショットキー電極
19 オーミック電極
20 アルミナ
21 熱電変換素子
22 アルミナ
23 銅
1 SiC diode element
2 Diode terminal
3 Thermoelectric conversion element
4 Thermoelectric conversion element terminal
5 High thermal conductivity insulation
6 Heat dissipation fin
7 bands
8 Fin clasp
9 DC voltage source
10 Choke inductor
11 MOSFET
12 diodes
13 Output capacitor
14 Load resistance
15 High frequency voltage generator
16 SiC substrate
17 GaN epilayer
18 Schottky electrode
19 Ohmic electrode
20 Alumina
21 Thermoelectric conversion element
22 Alumina
23 Copper

Claims (6)

炭化珪素、ガリウム砒素、窒化ガリウム、ダイヤモンド、またはこれらを複合した材料であって150℃以上の温度でも動作する半導体材料と、熱電変換材料とを、熱伝導率が1.0W/m・K以上の電気絶縁材料を介して熱伝導可能に対向させて一体とし、半導体材料からの発熱を利用して熱電変換材料により発電することができ、また、熱電変換材料に通電して半導体材料を冷却できることを特徴する電力変換素子。 Silicon carbide, gallium arsenide, gallium nitride, diamond, or a composite material of these materials that can operate at temperatures of 150 ° C or higher and thermoelectric conversion materials with a thermal conductivity of 1.0 W / m · K or higher It is possible to generate heat with the thermoelectric conversion material using heat generated from the semiconductor material, and to cool the semiconductor material by energizing the thermoelectric conversion material. A power conversion element characterized by 前記半導体材料と熱電変換材料とを電気絶縁材料を介して一体にし、ディスクリート構成の素子にしたことを特徴とする請求項1の電力変換素子。 2. The power conversion element according to claim 1, wherein the semiconductor material and the thermoelectric conversion material are integrated with each other through an electric insulating material to form a discrete element. 前記半導体材料を用いて形成したディスクリート構成の半導体素子と、前記熱電変換材料を用いて形成した熱電変換素子とが、電気絶縁材料を介して一体にされたことを特徴とする請求項1の電力変換素子。 2. The electric power according to claim 1 , wherein a semiconductor element having a discrete structure formed by using the semiconductor material and a thermoelectric conversion element formed by using the thermoelectric conversion material are integrated with each other through an electrically insulating material. Conversion element. 150℃以上の温度で動作させた半導体材料からの発熱を利用して熱電変換材料により発電を行うことを特徴とする請求項1の電力変換素子。 2. The power conversion element according to claim 1, wherein power generation is performed by a thermoelectric conversion material using heat generated from a semiconductor material operated at a temperature of 150 ° C. or higher . 半導体材料の設定動作温度上限を超えた場合に、熱電変換材料へ通電を行い、半導体材料を冷却することを特徴とする請求項1の電力変換素子。   2. The power conversion element according to claim 1, wherein when the set operating temperature upper limit of the semiconductor material is exceeded, the thermoelectric conversion material is energized to cool the semiconductor material. 電力変換が20KHz以上の高周波で行われることを特徴とする請求項1の電力変換素子。   The power conversion element according to claim 1, wherein the power conversion is performed at a high frequency of 20 KHz or more.
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