JP2006294431A - Induction heating device - Google Patents
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- JP2006294431A JP2006294431A JP2005114148A JP2005114148A JP2006294431A JP 2006294431 A JP2006294431 A JP 2006294431A JP 2005114148 A JP2005114148 A JP 2005114148A JP 2005114148 A JP2005114148 A JP 2005114148A JP 2006294431 A JP2006294431 A JP 2006294431A
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本発明は、アルミ鍋のような高導電率かつ低透磁率の被加熱物を効率良く誘導加熱できるようにした誘導加熱調理器や、誘導加熱式の湯沸かし器、加湿器あるいはアイロンなどの誘導加熱装置に関するものである。 The present invention relates to an induction heating cooker, an induction heating type water heater, a humidifier, an iron, or the like which can efficiently heat an object to be heated having high conductivity and low permeability such as an aluminum pan. It is about.
以下、従来の誘導加熱装置の例として、加熱コイルから高周波磁界を発生し、電磁誘導による渦電流によって鍋等の負荷を加熱して調理する誘導加熱調理器について図５、図６に基づいて説明する。 Hereinafter, as an example of a conventional induction heating apparatus, an induction heating cooker that generates a high-frequency magnetic field from a heating coil and heats a load such as a pan by an eddy current due to electromagnetic induction will be described with reference to FIGS. 5 and 6. To do.
図５は、従来の誘導加熱調理器の回路構成を示す図である。電源５１は低周波交流電源である２００Ｖ商用電源であり、ブリッジダイオードである整流回路５２の入力端に接続される。整流回路５２の出力端間に第１の平滑コンデンサ５３が接続される。整流回路５２の出力端間には、さらに、チョークコイル５４と第２のスイッチング素子５７の直列接続体が接続される。加熱コイル５９は被加熱物であるアルミニウム製の鍋６１と対向して配置されている。インバータ５０において、第２の平滑コンデンサ６２の低電位側端子（エミッタ）は整流回路５２の負極端子に接続され、第２の平滑コンデンサ６２の高電位側端子は第１のスイッチング素子（ＩＧＢＴ）５５の高電位側端子（コレクタ）に接続され、第１のスイッチング素子（ＩＧＢＴ）５５の低電位側端子はチョークコイル５４と第２のスイッチング素子（ＩＧＢＴ）５７の高電位側端子（コレクタ）との接続点に接続される。加熱コイル５９と共振コンデンサ６０の直列接続体が第２のスイッチング素子５７に並列に接続される。第１のダイオード５６（第１の逆導通素子）は第１のスイッチング素子５５に逆並列に接続（第１のダイオード５６のカソードと第１のスイッチング素子５５のコレクタとを接続）され、第２のダイオード５８（第２の逆導通素子）は第２のスイッチング素子５７に逆並列に接続される。スナバコンデンサ６４は、第２のスイッチング素子５７に並列に接続される。補正用共振コンデンサ６５とリレー６６の直列接続体は共振コンデンサ６０に並列に接続されている。制御回路６３は、電源５１からの入力電流を検知するカレントトランス６７と、加熱コイル５９の電流を検知するカレントトランス６８の検知信号を入力するとともに、第１のスイッチング素子５５と第２のスイッチング素子５７のゲートとリレー６６の駆動コイル（図示せず）に信号を出力する。 FIG. 5 is a diagram illustrating a circuit configuration of a conventional induction heating cooker. The power source 51 is a 200 V commercial power source that is a low-frequency AC power source, and is connected to an input terminal of a rectifier circuit 52 that is a bridge diode. A first smoothing capacitor 53 is connected between the output terminals of the rectifier circuit 52. A series connection body of the choke coil 54 and the second switching element 57 is further connected between the output terminals of the rectifier circuit 52. The heating coil 59 is arranged to face the aluminum pan 61 that is the object to be heated. In the inverter 50, the low potential side terminal (emitter) of the second smoothing capacitor 62 is connected to the negative terminal of the rectifier circuit 52, and the high potential side terminal of the second smoothing capacitor 62 is the first switching element (IGBT) 55. The low potential side terminal of the first switching element (IGBT) 55 is connected to the high potential side terminal (collector) of the choke coil 54 and the second switching element (IGBT) 57. Connected to the connection point. A series connection body of the heating coil 59 and the resonance capacitor 60 is connected to the second switching element 57 in parallel. The first diode 56 (first reverse conducting element) is connected in antiparallel to the first switching element 55 (the cathode of the first diode 56 and the collector of the first switching element 55 are connected), and the second The diode 58 (second reverse conducting element) is connected to the second switching element 57 in antiparallel. The snubber capacitor 64 is connected in parallel to the second switching element 57. A series connection body of the correcting resonance capacitor 65 and the relay 66 is connected to the resonance capacitor 60 in parallel. The control circuit 63 inputs detection signals of a current transformer 67 that detects an input current from the power source 51 and a current transformer 68 that detects a current of the heating coil 59, and the first switching element 55 and the second switching element. A signal is output to a gate 57 and a drive coil (not shown) of the relay 66.
以上のように構成された誘導加熱装置において、以下動作を説明する。電源５１は整流回路５２により全波整流され、整流回路５２の出力端に接続された第１の平滑コンデンサ５３に供給される。この第１の平滑コンデンサ５３はインバータ５０に高周波電流を供給する供給源として働く。図６は上記回路における各部波形を示す図であり、図６（Ａ）は出力が大出力である２ｋＷの時のものである。図６（Ａ）において、（ａ）は第１のスイッチング素子５５及び第１のダイオード５６に流れる電流波形Ｉｃ１を、（ｂ）は第２のスイッチング素子５７及び第２のダイオード５８に流れる電流波形Ｉｃ２を、（ｃ）は第２のスイッチング素子５７のコレクタ−エミッタ間に生じる電圧Ｖｃｅ２を、（ｄ）は第１のスイッチング素子５５のゲートに加わる駆動電圧Ｖｇ１を、（ｅ）は第２のスイッチング素子５７のゲートに加わる駆動電圧Ｖｇ２を、（ｆ）は加熱コイル５９に流れる電流ＩＬをそれぞれ示している。出力が２ｋＷのとき（図６（Ａ））、制御回路６３は時点ｔ０から時点ｔ１まで（ｅ）に示すように第２のスイッチング素子５７のゲートに駆動期間がＴ２（約２４μ秒）であるオン信号を出力する。この駆動期間Ｔ２の間では第２のスイッチング素子５７及び第２のダイオード５８と、加熱コイル５９と、共振コンデンサ６０で形成される閉回路で共振し、鍋６１がアルミニウム製の鍋であるときの共振周期（１／ｆ）が駆動期間Ｔ２の約２／３倍（約１６μ秒）となるように加熱コイル５９の巻き数（４０Ｔ）と共振コンデンサ６０の容量（０．０４μＦ）と、駆動期間Ｔ２が設定されている。チョークコイル５４はこの第２のスイッチング素子５７の駆動期間Ｔ２において、平滑コンデンサ５３の静電エネルギーを磁気エネルギーとして蓄える。次に、第２のスイッチング素子５７に流れる共振電流の第２番目のピークと共振電流が次に零となる間のタイミングである時点ｔ１、すなわち第２のスイッチング素子５７の順方向にコレクタ電流が流れている時点で第２のスイッチング素子５７の駆動が停止される。すると、第２のスイッチング素子５７がオフするので、第２のスイッチング素子５７のコレクタと接続されたチョークコイル５４の端子の電位が立ち上がり、この電位が第２の平滑コンデンサ６２の電位を越えると、第１のダイオード５６を通して第２の平滑コンデンサ６２に充電して、チョークコイル５４に蓄えた磁気エネルギーを放出する。第２の平滑コンデンサ６２の電圧は整流器５２の直流出力電圧Ｖｄｃのピーク値（２８３Ｖ）よりも高くなるように昇圧される（従来例では５００Ｖ）。昇圧されるレベルは第２のスイッチング素子５７の導通時間に依存し、導通時間が長くなると第２の平滑コンデンサ６２に発生する電圧が高くなる傾向にある。このように、第２の平滑コンデンサ６２と第１のスイッチング素子５５あるいは第１のダイオード５６と加熱コイル５９と共振コンデンサ６０とで形成される閉回路で共振する際に直流電源として働く第２の平滑コンデンサ６２の電圧レベルが昇圧されることにより、図６（Ａ）の（ａ）に示す第１のスイッチング素子５５に流れる共振電流の尖頭値（ピーク値）、および共振経路を変えて、継続して共振する（ｂ）の第２のスイッチング素子５７に流れる共振電流の尖頭値が零とならないように、あるいは小さくならないようにして、アルミニウム製の鍋を高出力で誘導加熱し、かつ、出力を連続的に増減して制御するようにできる。そして、図６（Ａ）の（ｄ）及び（ｅ）で示すように、制御回路６３は、時点ｔ１から両スイッチング素子が同時に導通するのを防止するために設けた休止期間後の時点ｔ２において、第１のスイッチング素子５５のゲートに駆動信号を出力する。この結果、図６（Ａ）の（ａ）示すように加熱コイル５９と共振コンデンサ６０と第１のスイッチング素子５５または第１のダイオード５６と第２の平滑コンデンサ６２とからなる閉回路に経路を変えて共振電流が流れることになる。この駆動信号の駆動期間Ｔ２は、この場合にはＴ１とほぼ同じ期間に設定されているので、第２のスイッチング素子５７が導通していた場合と同様に、駆動期間Ｔ１の約２／３の周期の共振電流が流れる。従って、加熱コイル５９に流れる電流ＩＬは、図６（Ａ）の（ｆ）に示すような波形となり、第１及び第２のスイッチング素子５５、５７の駆動周期（Ｔ１とＴ２と休止期間の和）は共振電流の周期の約３倍となり、第１及び第２の駆動周波数が約２０ｋＨｚであれば、加熱コイル５９に流れる共振電流の周波数は約６０ｋＨｚとなる。次に起動時においては、制御回路６３はリレー６６はオフ状態にし、一定の周波数（約２１ｋＨｚ）で第１のスイッチング素子５５と第２のスイッチング素子５７を交互に駆動する。第１のスイッチング素子５５の駆動期間は共振電流の共振周期よりも短いモードで駆動し、駆動時間比を最小にして、最小の出力にしてから徐々に駆動時間比を増加し、その間に制御回路６３はカレントトランス６７の検知出力とカレントトランス６８の検知出力から、負荷鍋６１の材料を検知する。制御回路６３は負荷鍋６１の材料が鉄系のものであると判断すると、加熱を停止してからリレー６６を投入して、再度低出力で加熱を開始する。このとき、制御回路６３は第１のスイッチング素子５５と第２のスイッチング素子５７を一定の周波数（約２１ｋＨｚ）で再度最小駆動時間比で最小出力からスタートして所定の出力まで徐々に増加させる。一方、鉄系の負荷であると検知しない場合には、所定の駆動時間比に到達すると、図６（Ｂ）に示すような、第１のスイッチング素子５７の駆動期間より共振電流の周期の短いモードに移行する。このとき、出力は低出力状態になるように駆動期間が設定される。以上のように、加熱コイル５９の発生する磁界によりアルミニウムや銅など高導電率、低透磁率の負荷を加熱すると、第１のスイッチング素子５５、第１ダイオード５６を流れる加熱コイル５９と共振コンデンサ６０による共振電流は、両スイッチング素子それぞれの駆動期間（Ｔ１）より短い周期で共振してなるので、第１のスイッチング素子５５の駆動周波数より高い周波数（従来例では１．５倍）の電流を加熱コイル５９に供給して加熱することができ、さらに、昇圧手段であるチョークコイル５４と平滑手段である第２の平滑コンデンサ６２を設けて、高周波電源である平滑コンデンサ６２の電圧を昇圧して平滑し、各駆動期間（Ｔ及びＴ’）において共振電流の振幅を大きくしているため、駆動開始後、共振電流が流れ始めてから１周期目が終了し、２周期目に到達して以降においても十分大きな振幅の共振電流を継続させることができるものである。また、制御回路６３は、最大出力設定時に、第１のスイッチング素子５５の駆動開始後、共振電流が２周期目以降であって第１のスイッチング素子５５に流れている期間内に第１のスイッチング素子５５の導通を遮断する信号を出力してなる、または、第２のスイッチング素子５７の駆動開始後共振電流が２周期目以降であって第２のスイッチング素子５７に流れている期間内に第２のスイッチング素子の導通を遮断する信号を出力してなるので、最大出力時の第２のスイッチング素子５７または第１のスイッチング素子５５のターンオン損失の増大を抑制することができる。また、起動時、第１のスイッチング素子５５と第２のスイッチング素子５７の駆動時間比を変え加熱出力を増加させ、途中から駆動周波数を変え加熱出力を増加させてなることにより、負荷の検知を行いやすくすることができる。すなわち、駆動時間比を変えることにより高導電率かつ低透磁率のアルミニウム等の材質の負荷でも鉄系の負荷でも低出力状態で単調に出力を変化させることができ、制御回路６３は負荷検知が正確にかつ低出力状態でできる。また、加熱コイル５９の発生する磁界により、鉄系の負荷または非磁性ステンレスの負荷６１を加熱すると共振電流は第１のスイッチング素子５５及び第２のスイッチング素子５７の導通期間より長い周期で共振してなり、鉄系の負荷または非磁性ステンレス製の負荷６１を最大出力で加熱する場合に第１のスイッチング素子５５及び第２のスイッチング素子５７に順方向に電流が流れているタイミングで前記スイッチング素子を遮断可能とするように補正用共振コンデンサ６５を共振コンデンサ６０に並列に接続して、高導電率かつ低透磁率の負荷を加熱する場合よりも大きい容量に切り替えてなるので、共振コンデンサ６０と補正用共振コンデンサ６５は加熱コイル５９と直列に接続されると共に容量を切り替え可能とし、鉄系の負荷または非磁性ステンレス製の負荷を加熱する場合に共振コンデンサ６０を、高導電率かつ低透磁率の負荷を加熱する場合よりも大きい容量に切り替えてなることにより、共振周波数が長くなるとともに電流が増え、さらにチョークコイル５４により直流電圧Ｖｄｃを昇圧しているので、共振電流の振幅が大きくなることから、スイッチング素子に順方向に電流が流れているタイミングでスイッチング素子を遮断可能な範囲で最大出力を設定してスイッチング素子のターンオン時のスイッチング損失の増大を抑制しようとする場合に、最大出力を以前の従来の構成のものより大きくすることができる。また、アルミニウム系の鍋と、鉄系の鍋を同一のインバータで加熱しようとするときに、他の従来例では加熱コイル５９の巻き数と共振コンデンサとを同時に切り替えて共振周波数と被加熱物６１に放射する磁界の強さ（アンペアターン）を切り替えていたが、チョークコイル５４と第１のスイッチング手段５７の昇圧作用により前記のコイル巻き数切り替えの作用を置き換えることができ、同一の加熱コイル５９で共振コンデンサ６０の切り替えをすることで、広い範囲の材質の被加熱物を加熱できる。また、補正用共振コンデンサ６５を共振コンデンサ６０に接続せずに起動し、すなわち、容量の小なる共振コンデンサ６０ので起動し、徐々に出力を増加させ、その途中で負荷６１が鉄系か、高導電率かつ低透磁率のものかを判定し、鉄系の負荷であると判定した場合には駆動停止後、リレー６０をオンして補正用共振コンデンサ６５を並列に接続して、すなわち、共振コンデンサ６０を容量が大となるよう切り変え、駆動周波数を低周波数で再駆動するので、共振周波数が長くなるとともに電流が増え、さらに昇圧手段であるチョークコイル５４と第２の平滑コンデンサ６２により直流電源電圧を昇圧しているので、共振電流値が増えることから、第１のスイッチング素子５５及びに順方向に電流が流れているタイミングでスイッチング素子を遮断可能な範囲で最大出力を設定して第２のスイッチング素子５７のターンオン時のスイッチング損失の増大を抑制しようとする場合に、最大出力を以前の従来の構成のものより大きくすることができる。また、高導電率、低透磁率の負荷であると判定した場合には継続して所定の駆動時間比または所定の出力まで出力を増加した後駆動時間比を固定して導通時間を変更して出力を所定の出力に到達させてなるので、いずれの負荷においても低出力で起動して負荷の判定をして、安定的に所定の出力値あるいはリミット値へと到達させるいわゆるソフトスタート動作が可能となる。 The operation of the induction heating apparatus configured as described above will be described below. The power supply 51 is full-wave rectified by a rectifier circuit 52 and supplied to a first smoothing capacitor 53 connected to the output terminal of the rectifier circuit 52. The first smoothing capacitor 53 serves as a supply source for supplying a high frequency current to the inverter 50. FIG. 6 is a diagram showing the waveform of each part in the above circuit, and FIG. 6 (A) is the one when the output is 2 kW, which is a large output. 6A, FIG. 6A shows a current waveform Ic1 flowing through the first switching element 55 and the first diode 56, and FIG. 6B shows a current waveform flowing through the second switching element 57 and the second diode 58. Ic2, (c) is the voltage Vce2 generated between the collector and the emitter of the second switching element 57, (d) is the drive voltage Vg1 applied to the gate of the first switching element 55, and (e) is the second voltage. The driving voltage Vg2 applied to the gate of the switching element 57 is shown, and (f) shows the current IL flowing through the heating coil 59. When the output is 2 kW (FIG. 6 (A)), the control circuit 63 has a driving period T2 (about 24 μsec) at the gate of the second switching element 57 as shown in (e) from time t0 to time t1. Outputs an on signal. During this driving period T2, the second switching element 57 and the second diode 58, the heating coil 59, and the resonant capacitor 60 resonate in a closed circuit, and the pot 61 is an aluminum pot. The number of turns of the heating coil 59 (40T), the capacity of the resonant capacitor 60 (0.04 μF), and the driving period so that the resonance period (1 / f) is about 2/3 times (about 16 μs) the driving period T2. T2 is set. The choke coil 54 stores the electrostatic energy of the smoothing capacitor 53 as magnetic energy during the driving period T2 of the second switching element 57. Next, the collector current is applied at the time t1, which is the timing between the second peak of the resonance current flowing in the second switching element 57 and the resonance current next becoming zero, that is, in the forward direction of the second switching element 57. At the time of flowing, the driving of the second switching element 57 is stopped. Then, since the second switching element 57 is turned off, the potential of the terminal of the choke coil 54 connected to the collector of the second switching element 57 rises, and when this potential exceeds the potential of the second smoothing capacitor 62, The second smoothing capacitor 62 is charged through the first diode 56 to release the magnetic energy stored in the choke coil 54. The voltage of the second smoothing capacitor 62 is boosted so as to be higher than the peak value (283 V) of the DC output voltage Vdc of the rectifier 52 (500 V in the conventional example). The level to be boosted depends on the conduction time of the second switching element 57, and the voltage generated in the second smoothing capacitor 62 tends to increase as the conduction time increases. As described above, the second smoothing capacitor 62 and the first switching element 55 or the first diode 56, the heating coil 59, and the resonant capacitor 60 resonate in a closed circuit, and serve as a DC power source. By increasing the voltage level of the smoothing capacitor 62, the peak value (peak value) of the resonance current flowing through the first switching element 55 shown in (a) of FIG. The aluminum pan is induction-heated with high output so that the peak value of the resonance current flowing through the second switching element 57 that continuously resonates does not become zero or becomes small, and The output can be controlled by increasing or decreasing continuously. Then, as shown in (d) and (e) of FIG. 6 (A), the control circuit 63 starts at time t2 after an idle period provided to prevent both switching elements from conducting simultaneously from time t1. A drive signal is output to the gate of the first switching element 55. As a result, as shown in FIG. 6A, a path is formed in a closed circuit including the heating coil 59, the resonant capacitor 60, the first switching element 55 or the first diode 56, and the second smoothing capacitor 62. Instead, the resonance current flows. Since the drive period T2 of this drive signal is set to substantially the same period as T1 in this case, it is about 2/3 of the drive period T1 as in the case where the second switching element 57 is conductive. Periodic resonance current flows. Therefore, the current IL flowing through the heating coil 59 has a waveform as shown in (f) of FIG. 6A, and the driving cycle of the first and second switching elements 55 and 57 (the sum of T1 and T2 and the rest period). ) Is about three times the period of the resonance current, and if the first and second drive frequencies are about 20 kHz, the frequency of the resonance current flowing through the heating coil 59 is about 60 kHz. Next, at the time of start-up, the control circuit 63 turns off the relay 66 and drives the first switching element 55 and the second switching element 57 alternately at a constant frequency (about 21 kHz). The drive period of the first switching element 55 is driven in a mode shorter than the resonance period of the resonance current, the drive time ratio is minimized, and the drive time ratio is gradually increased after the minimum output is achieved. 63 detects the material of the load pan 61 from the detection output of the current transformer 67 and the detection output of the current transformer 68. When the control circuit 63 determines that the material of the load pan 61 is iron-based, the heating is stopped, the relay 66 is turned on, and heating is started again at a low output. At this time, the control circuit 63 gradually increases the first switching element 55 and the second switching element 57 from a minimum output at a constant frequency (about 21 kHz) with a minimum drive time ratio to a predetermined output. On the other hand, when it is not detected that the load is iron-based, when the predetermined drive time ratio is reached, the period of the resonance current is shorter than the drive period of the first switching element 57 as shown in FIG. Enter mode. At this time, the drive period is set so that the output is in a low output state. As described above, when a high-conductivity and low-permeability load such as aluminum or copper is heated by the magnetic field generated by the heating coil 59, the heating coil 59 and the resonant capacitor 60 that flow through the first switching element 55 and the first diode 56 are used. Since the resonance current due to the resonance occurs at a period shorter than the drive period (T1) of each of the switching elements, a current having a frequency higher than the drive frequency of the first switching element 55 (1.5 times in the conventional example) is heated. The coil 59 can be supplied and heated. Further, a choke coil 54 as a boosting means and a second smoothing capacitor 62 as a smoothing means are provided to boost and smooth the voltage of the smoothing capacitor 62 as a high frequency power source. Since the amplitude of the resonance current is increased in each drive period (T and T ′), the resonance current starts to flow after the drive starts. Th cycle is completed, the subsequent reached the second cycle also is capable to continue the resonance current of sufficiently large amplitude. In addition, when the maximum output is set, the control circuit 63 performs the first switching within a period in which the resonance current is flowing in the first switching element 55 after the start of driving of the first switching element 55. A signal that cuts off the conduction of the element 55 is output, or after the second switching element 57 starts to be driven, the resonance current is flowing in the second switching element 57 after the second period and flowing through the second switching element 57. Since the signal for shutting off the conduction of the second switching element is output, an increase in turn-on loss of the second switching element 57 or the first switching element 55 at the maximum output can be suppressed. In addition, at the time of start-up, load ratio is detected by changing the driving time ratio of the first switching element 55 and the second switching element 57 to increase the heating output and changing the driving frequency from the middle to increase the heating output. It can be made easier. That is, by changing the drive time ratio, the output can be monotonously changed in a low output state, whether it is a load of a material such as aluminum having a high conductivity and a low magnetic permeability or an iron load, and the control circuit 63 can detect the load. Accurate and low power state. Further, when an iron-based load or a nonmagnetic stainless steel load 61 is heated by the magnetic field generated by the heating coil 59, the resonance current resonates at a period longer than the conduction period of the first switching element 55 and the second switching element 57. When the iron-based load or the non-magnetic stainless steel load 61 is heated at the maximum output, the switching element is activated at the timing when the current flows in the first switching element 55 and the second switching element 57 in the forward direction. The correction resonance capacitor 65 is connected in parallel to the resonance capacitor 60 so as to be able to cut off, and the capacitance is switched to a larger capacity than when heating a load with high conductivity and low magnetic permeability. The correcting resonance capacitor 65 is connected in series with the heating coil 59 and can switch the capacity, so that the iron load or the like can be switched. When heating a non-magnetic stainless steel load, the resonant capacitor 60 is switched to a larger capacity than when heating a high-conductivity and low-permeability load, thereby increasing the resonance frequency and increasing the current. In addition, since the DC voltage Vdc is boosted by the choke coil 54, the amplitude of the resonance current increases, so that the maximum output can be achieved within a range in which the switching element can be cut off at the timing when the current flows through the switching element in the forward direction. When it is set to suppress an increase in switching loss when the switching element is turned on, the maximum output can be made larger than that of the previous conventional configuration. Further, when an aluminum pan and an iron pan are to be heated by the same inverter, in another conventional example, the number of turns of the heating coil 59 and the resonance capacitor are simultaneously switched to change the resonance frequency and the object 61 to be heated. The strength of the magnetic field radiated (ampere turn) is switched. However, the boosting action of the choke coil 54 and the first switching means 57 can replace the action of switching the number of coil turns, and the same heating coil 59 can be replaced. By switching the resonance capacitor 60, it is possible to heat an object to be heated in a wide range. Further, the correction resonance capacitor 65 is started without being connected to the resonance capacitor 60, that is, is started with the resonance capacitor 60 having a small capacity, and the output is gradually increased. It is determined whether it has conductivity and low magnetic permeability. If it is determined that the load is an iron-based load, after the drive is stopped, the relay 60 is turned on and the correcting resonance capacitor 65 is connected in parallel. Since the capacitor 60 is switched to have a large capacity and the drive frequency is re-driven at a low frequency, the resonance frequency is increased and the current is increased. Further, the choke coil 54 as the boosting means and the second smoothing capacitor 62 are used for direct current. Since the power supply voltage is boosted, the resonance current value increases, so that the switching element is switched at the timing when the current flows in the forward direction to the first switching element 55. When the maximum output is set in a range in which the second switching element 57 can be cut off to suppress an increase in switching loss when the second switching element 57 is turned on, the maximum output can be made larger than that of the previous conventional configuration. . If it is determined that the load has high conductivity and low permeability, the drive time ratio is continuously fixed and the conduction time is changed by increasing the output to a predetermined drive time ratio or a predetermined output. Since the output reaches a predetermined output, so-called soft start operation is possible to start at a low output at any load, determine the load, and stably reach the predetermined output value or limit value. It becomes.
以上のように構成された誘導加熱装置において、高導電率かつ低透磁率のアルミニウム等の材質の負荷でも鉄系の負荷でも負荷検知が正確にかつ低出力状態でできることからリレーのオンオフを切り替えることにより、共振コンデンサの切り替えを行い負荷の材質に応じた誘導加熱を可能としているものであった。
しかしながら、このような従来の構成では、高導電率かつ低透磁率のアルミニウム等の材質の負荷と鉄系の負荷との中間材質すなわち比較的厚い非磁性ステンレスや薄いステンレスの上にアルミニウムを組み合わせた複合材などにおいて充分な出力を得るにはさらに共振コンデンサを切り替えるなど構成が複雑になり、共振コンデンサを切り替えなければ充分な出力を得ることが困難であるという課題を有していた。 However, in such a conventional configuration, aluminum is combined on an intermediate material between a load of a material such as aluminum having a high conductivity and a low magnetic permeability and an iron load, that is, a relatively thick nonmagnetic stainless steel or a thin stainless steel. In order to obtain a sufficient output in a composite material or the like, the configuration is further complicated such as switching the resonance capacitor, and there is a problem that it is difficult to obtain a sufficient output unless the resonance capacitor is switched.
本発明は、前記従来の課題を解決するもので、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じて加熱モードを切り替え、より大きな出力を得ることができ、さらに加熱モードの切り替えを加熱を停止することなく連続して加熱を継続する誘導加熱装置を提供することを目的とする。 The present invention solves the above-mentioned conventional problems, and can easily heat the intermediate material load with a larger output with a simple configuration and switch the heating mode according to the material of the load from high conductivity to low conductivity, An object of the present invention is to provide an induction heating apparatus that can obtain a larger output and that can continue heating without switching heating mode switching.
前記従来の課題を解決するために、本発明の誘導加熱装置は駆動周期内に第１のスイッチング素子の駆動期間内に半周期以内の共振電流を流し、第２のスイッチング素子の駆動期間内に１周期以上の共振電流を流す信号を出力してなる中間材質モードを有し負荷検知結果に応じて負荷材質のモードを切り替え、モードの切り替えにおいてインバータの動作を継続して行う構成としたものである。 In order to solve the above-described conventional problems, the induction heating apparatus of the present invention allows a resonance current within a half cycle to flow within a driving period of the first switching element within a driving period, and within a driving period of the second switching element. It has an intermediate material mode that outputs a signal that passes a resonance current of one cycle or more, and switches the load material mode according to the load detection result, and the operation of the inverter is continued in the mode switching. is there.
これによって、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じて加熱モードを切り替えることができ、さらに加熱モードの切り替えを加熱を停止することなく連続して加熱を継続できる誘導加熱装置を提供することを目的とする。 As a result, the load of the intermediate material can be induction-heated with a larger output with a simple configuration, and the heating mode can be switched according to the material of the load from high conductivity to low conductivity. It aims at providing the induction heating apparatus which can continue a heating continuously, without stopping.
本発明の誘導加熱装置は、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じてより加熱出力を大きくすることができ、かつ、加熱モードの切り替えを加熱を停止することなく連続して加熱を継続できる。 The induction heating device of the present invention can easily heat the intermediate material load with a large output with a simple configuration, and can increase the heating output depending on the material of the load from high conductivity to low conductivity, and The heating mode can be switched continuously without stopping the heating.
第１の発明は、第１のスイッチング素子と第２のスイッチング素子の直列接続体と、前記第１のスイッチング素子に並列に接続された第１の逆導通素子と、前記第２のスイッチング素子に並列に接続された第２の逆導通素子と、前記第１のスイッチング素子または前記第２のスイッチング素子に並列に接続された加熱コイルと共振コンデンサを含む共振回路とを有し直流電圧を入力して前記第１のスイッチング素子と第２のスイッチング素子の導通により共振するインバータと、前記第１のスイッチング素子と前記第２のスイッチング素子を排他的に導通制御する制御回路と負荷の材質を検知する負荷材質検知手段を備え、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が高導電率かつ低透磁率の負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、前記第１のスイッチング素子を駆動開始後、前記共振電流が前記第１のスイッチング素子に流れ始めてから２周期目に到達して以降であって前記第１のスイッチング素子に電流が流れている期間内において前記第１のスイッチング素子の駆動を停止する信号を出力してなる高導電率材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、駆動周期内に前記第１のスイッチング素子の駆動期間内に半周期以内の共振電流を流し、前記第２のスイッチング素子の駆動期間内に１周期以上の共振電流を流す信号を出力してなる中間材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期で共振し前記制御回路は、駆動周期内に前記第１のスイッチング素子の駆動期間内に半周期以内の共振電流を流し、前記第２のスイッチング素子の駆動期間内に半周期以内の共振電流を流す信号を出力してなる低導電率材質モードとを有し、負荷材質検知結果に応じて高導電率材質モードと中間材質モードと低導電率材質モードのいずれかで動作させ、前記３つの材質モードの切替において前記インバータの動作を継続して行う構成とすることにより、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じて加熱モードを切り替えることができ、さらに加熱モードの切り替えを加熱を停止することなく連続して加熱を継続できる。 According to a first aspect of the present invention, there is provided a serial connection body of a first switching element and a second switching element, a first reverse conducting element connected in parallel to the first switching element, and the second switching element. A second reverse conducting element connected in parallel; a heating circuit connected in parallel to the first switching element or the second switching element; and a resonance circuit including a resonance capacitor; Detecting an inverter that resonates due to conduction between the first switching element and the second switching element, a control circuit that exclusively controls conduction of the first switching element and the second switching element, and a material of the load. Load material detecting means, and the resonance current flowing through the first switching element or the first reverse conducting element is a highly conductive magnetic field generated by the heating coil. When a load having a low magnetic permeability is induction-heated, the DC voltage is boosted so that the resonance resonates with a cycle shorter than the drive cycle of the first switching element and the resonance current keeps resonance with a predetermined amplitude or more in the drive cycle. The control circuit is boosted and smoothed by the smoothing means so as to be higher than the peak value of the input DC voltage of the pulsating current, and is supplied to the inverter. The control circuit starts driving the first switching element, and then resonates. A signal for stopping the driving of the first switching element after the current has started to flow to the first switching element and after the second period has been reached and the current is flowing to the first switching element. And a resonance current flowing through the first switching element or the first reverse conducting element is the heating current mode. When the magnetic field generated by the coil inductively heats the load, the DC voltage is boosted to resonate at a cycle shorter than the drive cycle of the first switching element and to maintain the resonance current at a predetermined amplitude or more in the drive cycle. The smoothing means boosts the voltage so as to be higher than the peak value of the input DC voltage of the pulsating current, smoothes it and supplies it to the inverter, and the control circuit drives the driving period of the first switching element within the driving cycle. An intermediate material mode in which a resonance current within a half cycle flows and a signal for flowing a resonance current of one cycle or more within the driving period of the second switching element is output; and the first switching element or the first switching element When the magnetic field generated by the heating coil inductively heats the load, the resonance current flowing through the one reverse conducting element is shared by the driving cycle of the first switching element. The control circuit causes a resonance current within a half cycle to flow within a driving period of the first switching element within a driving cycle, and causes a resonance current within a half cycle to flow within a driving period of the second switching element. A low-conductivity material mode that outputs a signal, and operates in any of the high-conductivity material mode, intermediate material mode, and low-conductivity material mode according to the load material detection result, and the three material modes By switching the inverter, the operation of the inverter is continuously performed, so that the load of the intermediate material can be induction-heated with a larger output with a simple structure, and at the same time, the heating can be performed according to the material of the load from high conductivity to low conductivity. The mode can be switched, and the heating mode can be switched continuously without stopping the heating.
第２の発明は、第１のスイッチング素子と第２のスイッチング素子の直列接続体と、前記第１のスイッチング素子に並列に接続された第１の逆導通素子と、前記第２のスイッチング素子に並列に接続された第２の逆導通素子と、前記第１のスイッチング素子または前記第２のスイッチング素子に並列に接続された加熱コイルと共振コンデンサを含む共振回路とを有し直流電圧を入力して前記第１のスイッチング素子と第２のスイッチング素子の導通により共振するインバータと、前記第１のスイッチング素子と前記第２のスイッチング素子を排他的に導通制御する制御回路と負荷の材質を検知する負荷材質検知手段を備え、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が高導電率かつ低透磁率の負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、前記第１のスイッチング素子を駆動開始後、前記共振電流が前記第１のスイッチング素子に流れ始めてから２周期目に到達して以降であって前記第１のスイッチング素子に電流が流れている期間内において前記第１のスイッチング素子の駆動を停止する信号を出力してなる高導電率材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、駆動周期内に前記第１のスイッチング素子の駆動期間内に半周期以内の共振電流を流し、前記第２のスイッチング素子の駆動期間内に１周期以上の共振電流を流す信号を出力してなる中間材質モードとを有し、負荷材質検知結果に応じて高導電率材質モードと中間材質モードとの切替において前記インバータの動作を継続して行う構成とすることにより、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じて加熱モードを切り替えることができ、さらに高導電率材質モードと中間材質モードとの加熱モードの切り替えを加熱を停止することなく連続して加熱を継続できる。 According to a second aspect of the present invention, there is provided a serial connection body of the first switching element and the second switching element, a first reverse conducting element connected in parallel to the first switching element, and the second switching element. A second reverse conducting element connected in parallel; a heating circuit connected in parallel to the first switching element or the second switching element; and a resonance circuit including a resonance capacitor; Detecting an inverter that resonates due to conduction between the first switching element and the second switching element, a control circuit that exclusively controls conduction of the first switching element and the second switching element, and a material of the load. Load material detecting means, and the resonance current flowing through the first switching element or the first reverse conducting element is a highly conductive magnetic field generated by the heating coil. When a load having a low magnetic permeability is induction-heated, the DC voltage is boosted so that the resonance resonates with a cycle shorter than the drive cycle of the first switching element and the resonance current keeps resonance with a predetermined amplitude or more in the drive cycle. The control circuit is boosted and smoothed by the smoothing means so as to be higher than the peak value of the input DC voltage of the pulsating current, and is supplied to the inverter. The control circuit starts driving the first switching element, and then resonates. A signal for stopping the driving of the first switching element after the current has started to flow to the first switching element and after the second period has been reached and the current is flowing to the first switching element. And a resonance current flowing through the first switching element or the first reverse conducting element is the heating current mode. When the magnetic field generated by the coil inductively heats the load, the DC voltage is boosted to resonate at a cycle shorter than the drive cycle of the first switching element and to maintain the resonance current at a predetermined amplitude or more in the drive cycle. The smoothing means boosts the voltage so as to be higher than the peak value of the input DC voltage of the pulsating current, smoothes it and supplies it to the inverter, and the control circuit drives the driving period of the first switching element within the driving cycle. An intermediate material mode in which a resonance current within half a cycle flows and a signal that causes a resonance current to flow for one cycle or more within the driving period of the second switching element is output, and depending on the load material detection result By switching the high conductivity material mode and intermediate material mode, the operation of the inverter is continuously performed. Induction heating can be performed with a larger output, and the heating mode can be switched according to the material of the load from high conductivity to low conductivity, and the heating mode can be switched between the high conductivity material mode and the intermediate material mode. Heating can be continued continuously without stopping.
第３の発明は、第１のスイッチング素子と第２のスイッチング素子の直列接続体と、前記第１のスイッチング素子に並列に接続された第１の逆導通素子と、前記第２のスイッチング素子に並列に接続された第２の逆導通素子と、前記第１のスイッチング素子または前記第２のスイッチング素子に並列に接続された加熱コイルと共振コンデンサを含む共振回路とを有し直流電圧を入力して前記第１のスイッチング素子と第２のスイッチング素子の導通により共振するインバータと、前記第１のスイッチング素子と前記第２のスイッチング素子を排他的に導通制御する制御回路と負荷の材質を検知する負荷材質検知手段を備え、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が高導電率かつ低透磁率の負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、前記第１のスイッチング素子を駆動開始後、前記共振電流が前記第１のスイッチング素子に流れ始めてから２周期目に到達して以降であって前記第１のスイッチング素子に電流が流れている期間内において前記第１のスイッチング素子の駆動を停止する信号を出力してなる高導電率材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、駆動周期内に前記第１のスイッチング素子の駆動期間内に半周期以内の共振電流を流し、前記第２のスイッチング素子の駆動期間内に１周期以上の共振電流を流す信号を出力してなる中間材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期で共振する低導電率材質モードとを有し、負荷材質検知結果に応じて高導電率材質モードと中間材質モードと低導電率材質モードのいずれかで動作させ、中間材質モードにおいて負荷材質検知手段により負荷が高導電率材質であると検知することにより高導電率材質モードに切替を行う構成とすることにより、高導電率材質の負荷を中間材質モードで加熱した場合にスイッチング素子のスイッチング損失が増大するのを低減することができる。従って、より加熱出力が大きくすることができる。 According to a third aspect of the present invention, there is provided a serial connection body of the first switching element and the second switching element, a first reverse conducting element connected in parallel to the first switching element, and the second switching element. A second reverse conducting element connected in parallel; a heating circuit connected in parallel to the first switching element or the second switching element; and a resonance circuit including a resonance capacitor; Detecting an inverter that resonates due to conduction between the first switching element and the second switching element, a control circuit that exclusively controls conduction of the first switching element and the second switching element, and a material of the load. Load material detecting means, and the resonance current flowing through the first switching element or the first reverse conducting element is a highly conductive magnetic field generated by the heating coil. When a load having a low magnetic permeability is induction-heated, the DC voltage is boosted so that the resonance resonates with a cycle shorter than the drive cycle of the first switching element and the resonance current keeps resonance with a predetermined amplitude or more in the drive cycle. The control circuit is boosted and smoothed by the smoothing means so as to be higher than the peak value of the input DC voltage of the pulsating current, and is supplied to the inverter. The control circuit starts driving the first switching element, and then resonates. A signal for stopping the driving of the first switching element after the current has started to flow to the first switching element and after the second period has been reached and the current is flowing to the first switching element. And a resonance current flowing through the first switching element or the first reverse conducting element is the heating current mode. When the magnetic field generated by the coil inductively heats the load, the DC voltage is boosted to resonate at a cycle shorter than the drive cycle of the first switching element and to maintain the resonance current at a predetermined amplitude or more in the drive cycle. The smoothing means boosts the voltage so as to be higher than the peak value of the input DC voltage of the pulsating current, smoothes it and supplies it to the inverter, and the control circuit drives the driving period of the first switching element within the driving cycle. An intermediate material mode in which a resonance current within a half cycle flows and a signal for flowing a resonance current of one cycle or more within the driving period of the second switching element is output; and the first switching element or the first switching element When the magnetic field generated by the heating coil inductively heats the load, the resonance current flowing through the one reverse conducting element is shared by the driving cycle of the first switching element. The low-conductivity material mode is operated, and is operated in any of the high-conductivity material mode, intermediate material mode, and low-conductivity material mode according to the load material detection result. By switching to the high conductivity material mode by detecting that the load is a high conductivity material, switching loss of the switching element increases when the high conductivity material load is heated in the intermediate material mode Can be reduced. Therefore, the heating output can be further increased.
第４の発明は、第１のスイッチング素子と第２のスイッチング素子の直列接続体と、前記第１のスイッチング素子に並列に接続された第１の逆導通素子と、前記第２のスイッチング素子に並列に接続された第２の逆導通素子と、前記第１のスイッチング素子または前記第２のスイッチング素子に並列に接続された加熱コイルと共振コンデンサを含む共振回路とを有し直流電圧を入力して前記第１のスイッチング素子と第２のスイッチング素子の導通により共振するインバータと、前記第１のスイッチング素子と前記第２のスイッチング素子を排他的に導通制御する制御回路と負荷の材質を検知する負荷材質検知手段を備え、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が高導電率かつ低透磁率の負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、前記第１のスイッチング素子を駆動開始後、前記共振電流が前記第１のスイッチング素子に流れ始めてから２周期目に到達して以降であって前記第１のスイッチング素子に電流が流れている期間内において前記第１のスイッチング素子の駆動を停止する信号を出力してなる高導電率材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期より短い周期で共振するとともに前記駆動周期において前記共振電流が所定以上の振幅で共振を維持すべく前記直流電圧は昇圧平滑手段により脈流の入力直流電圧のピーク値よりも高くなるように昇圧されかつ平滑されて前記インバータに供給されてなり、前記制御回路は、駆動周期内に前記第１のスイッチング素子の駆動期間内に半周期以内の共振電流を流し、前記第２のスイッチング素子の駆動期間内に１周期以上の共振電流を流す信号を出力してなる中間材質モードと、前記第１のスイッチング素子または前記第１の逆導通素子に流れる共振電流は、前記加熱コイルの発生する磁界が負荷を誘導加熱すると前記第１のスイッチング素子の駆動周期で共振する低導電率材質モードとを有し、負荷材質検知結果に応じて高導電率材質モードと中間材質モードと低導電率材質モードのいずれかで動作させ、中間材質モードにおいて負荷材質検知手段により負荷が高導電率材質であると検知することにより加熱出力の抑制を行う構成とすることにより、高導電率材質の負荷を中間材質モードで加熱した場合にスイッチング素子のスイッチング損失が増大するのを低減することができる。 According to a fourth aspect of the present invention, there is provided a serial connection body of the first switching element and the second switching element, a first reverse conducting element connected in parallel to the first switching element, and the second switching element. A second reverse conducting element connected in parallel; a heating circuit connected in parallel to the first switching element or the second switching element; and a resonance circuit including a resonance capacitor; Detecting an inverter that resonates due to conduction between the first switching element and the second switching element, a control circuit that exclusively controls conduction of the first switching element and the second switching element, and a material of the load. Load material detecting means, and the resonance current flowing through the first switching element or the first reverse conducting element is a highly conductive magnetic field generated by the heating coil. When a load having a low magnetic permeability is induction-heated, the DC voltage is boosted so that the resonance resonates with a cycle shorter than the drive cycle of the first switching element and the resonance current keeps resonance with a predetermined amplitude or more in the drive cycle. The control circuit is boosted and smoothed by the smoothing means so as to be higher than the peak value of the input DC voltage of the pulsating current, and is supplied to the inverter. The control circuit starts driving the first switching element, and then resonates. A signal for stopping the driving of the first switching element after the current has started to flow to the first switching element and after the second period has been reached and the current is flowing to the first switching element. And a resonance current flowing through the first switching element or the first reverse conducting element is the heating current mode. When the magnetic field generated by the coil inductively heats the load, the DC voltage is boosted to resonate at a cycle shorter than the drive cycle of the first switching element and to maintain the resonance current at a predetermined amplitude or more in the drive cycle. The smoothing means boosts the voltage so as to be higher than the peak value of the input DC voltage of the pulsating current, smoothes it and supplies it to the inverter, and the control circuit drives the driving period of the first switching element within the driving cycle. An intermediate material mode in which a resonance current within a half cycle flows and a signal for flowing a resonance current of one cycle or more within the driving period of the second switching element is output; and the first switching element or the first switching element When the magnetic field generated by the heating coil inductively heats the load, the resonance current flowing through the one reverse conducting element is shared by the driving cycle of the first switching element. The low-conductivity material mode is operated, and is operated in any of the high-conductivity material mode, intermediate material mode, and low-conductivity material mode according to the load material detection result. By configuring the load to be suppressed by detecting that the load is a high conductivity material, the switching loss of the switching element increases when the load of the high conductivity material is heated in the intermediate material mode. Can be reduced.
第５の発明は、特に、第３または第４の発明の中間材質モードにおいて、負荷材質検知手段は、入力電流と共振コンデンサ電圧を入力とするとすることにより、負荷材質検知を確実に行うことができかつ高導電率材質の負荷を中間材質モードで加熱した場合にスイッチング素子のスイッチング損失が増大するのを低減することができる。 In the fifth aspect of the invention, in particular, in the intermediate material mode of the third or fourth aspect of the invention, the load material detection means can reliably detect the load material by using the input current and the resonant capacitor voltage as inputs. In addition, when the load of the high conductivity material is heated in the intermediate material mode, the increase in the switching loss of the switching element can be reduced.
第６の発明は、特に、第３または第４の発明の負荷材質検知手段は、加熱コイル電流または共振コンデンサ電圧を入力とするとすることにより、負荷材質検知を容易に実施できかつ高導電率材質の負荷を中間材質モードで加熱した場合にスイッチング素子のスイッチング損失が増大するのを低減することができる。 In the sixth invention, in particular, the load material detecting means of the third or fourth invention can easily detect the load material by using the heating coil current or the resonance capacitor voltage as an input, and has a high conductivity material. When the load is heated in the intermediate material mode, the increase in switching loss of the switching element can be reduced.
第７の発明は、特に、第１〜６の発明において、中間材質モードで、制御回路は、駆動周期内に第１のスイッチング素子の駆動期間内に１周期以上の共振電流を流し、第２のスイッチング素子の駆動期間内に半周期以内の共振電流を流す信号を出力してなるとすることにより、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じて加熱モードを切り替えることができ、さらに加熱モードの切り替えを加熱を停止することなく連続して加熱を継続できる。 In a seventh aspect of the invention, in particular, in the first to sixth aspects of the invention, in the intermediate material mode, the control circuit causes a resonance current to flow for one period or more within the driving period of the first switching element within the driving period, and the second By outputting a signal that allows a resonance current within half a cycle to be output within the drive period of the switching element, the load of the intermediate material can be induction-heated with a larger output with a simple configuration and high conductivity to low conductivity The heating mode can be switched depending on the material of the load, and the heating mode can be switched continuously without stopping the heating.
以下、本発明の実施の形態について、図面を参照しながら説明する。なお、この実施の形態によって本発明が限定されるものではない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.
（実施の形態１）
図１は本発明の第１の実施の形態における誘導加熱装置である誘導加熱調理器の回路構成図であり、図２は誘導加熱装置である誘導加熱調理器の回路の各部波形を示す図である。
(Embodiment 1)
FIG. 1 is a circuit configuration diagram of an induction heating cooker that is an induction heating device according to a first embodiment of the present invention, and FIG. 2 is a diagram illustrating waveforms of respective parts of a circuit of the induction heating cooker that is an induction heating device. is there.
図１において、電源１２は２００Ｖ商用電源であり、ダイオードブリッジからなる整流手段１３と第１の平滑コンデンサ１４と昇圧手段１５と第２の平滑コンデンサ１６からなる昇圧平滑手段１１によって商用電源を昇圧した直流に変換し、インバータ８により高周波に変換され、高周波磁界を加熱コイル１に発生させる。鍋２は負荷であり、加熱コイル１と対向して設置する。共振コンデンサ３は、加熱コイル１とともに直列の共振回路を構成している。インバータ８は前記共振回路を出力としたシングルエンドプッシュプル構成となるよう第１のスイッチング素子４および第２のスイッチング素子６を接続している。第１のスイッチング素子４および第２のスイッチング素子６はそれぞれ逆並列に第１の逆導通素子５と第２の逆導通素子７としてダイオードを接続している。制御回路９により第１のスイッチング素子４と第２のスイッチング素子６を交互に駆動し、出力を増加させる場合にはスイッチング素子の駆動周波数が共振周波数に近づくように制御回路９によりスイッチング素子４、６を駆動し、カレントトランスからなる加熱出力検知手段１７により加熱出力を検知して所定の加熱出力が得られるようにする周波数制御のインバータとしている。起動時においては、制御回路９は一定の周波数（約２１ｋＨｚ）で第１のスイッチング素子４と第２のスイッチング素子６を交互に駆動する。 In FIG. 1, a power source 12 is a 200 V commercial power source, and the commercial power source is boosted by a boosting smoothing unit 11 including a rectifying unit 13 composed of a diode bridge, a first smoothing capacitor 14, a boosting unit 15, and a second smoothing capacitor 16. The direct current is converted into a direct current and is converted into a high frequency by the inverter 8, and a high frequency magnetic field is generated in the heating coil 1. The pan 2 is a load and is installed opposite to the heating coil 1. The resonance capacitor 3 constitutes a series resonance circuit together with the heating coil 1. The inverter 8 connects the first switching element 4 and the second switching element 6 so as to have a single-end push-pull configuration using the resonance circuit as an output. The first switching element 4 and the second switching element 6 are connected in reverse parallel with each other as a first reverse conducting element 5 and a second reverse conducting element 7. When the control circuit 9 alternately drives the first switching element 4 and the second switching element 6 to increase the output, the control circuit 9 causes the switching element 4, so that the drive frequency of the switching element approaches the resonance frequency. 6 is driven, and a heating control is performed by a heating output detecting means 17 comprising a current transformer so that a predetermined heating output can be obtained. At startup, the control circuit 9 alternately drives the first switching element 4 and the second switching element 6 at a constant frequency (about 21 kHz).
図３は負荷２の材質が異なる時の負荷材質検知手段１０の検知入力の特性図で、低導電率材質から高導電率材質になるにしたがい、同じ入力電流では共振コンデンサ電圧が高くなっている。第１のスイッチング素子４の駆動期間は共振電流の共振周期よりも短いモードで駆動し、駆動時間比を最小にして、最小の出力にしてから徐々に駆動時間比を増加し、その間に負荷材質検知手段１０はカレントトランス１７の検知出力（入力電流）と共振コンデンサ電圧検知手段１８の検知出力から、負荷２の材料を検知する。負荷材質検知手段１０は負荷２の材料が鉄系のものであると判断すると、駆動周波数を上げ、再度低出力で加熱を開始する。共振回路の共振周波数は約６０ｋＨｚとなるよう加熱コイル１および共振コンデンサ３を設定し、スイッチング素子の駆動周波数は共振回路の共振周波数である約６０ｋＨｚとなるようにして、最小出力からスタートして所定の出力まで徐々に増加させる低導電率材質モードで動作させる。 FIG. 3 is a characteristic diagram of the detection input of the load material detection means 10 when the material of the load 2 is different, and the resonance capacitor voltage becomes higher at the same input current as the low conductivity material is changed to the high conductivity material. . The drive period of the first switching element 4 is driven in a mode shorter than the resonance period of the resonance current, the drive time ratio is minimized, the drive time ratio is gradually increased after the output is minimized, The detection means 10 detects the material of the load 2 from the detection output (input current) of the current transformer 17 and the detection output of the resonance capacitor voltage detection means 18. When the load material detection means 10 determines that the material of the load 2 is iron-based, the drive frequency is increased and heating is started again at a low output. The heating coil 1 and the resonance capacitor 3 are set so that the resonance frequency of the resonance circuit is about 60 kHz, and the drive frequency of the switching element is set to about 60 kHz, which is the resonance frequency of the resonance circuit, and starts from the minimum output. Operate in low-conductivity material mode, gradually increasing up to the output.
一方、アルミニウム系の負荷であると検知した場合には、所定の駆動時間比に到達すると、第１のスイッチング素子４の駆動期間より共振電流の周期の短いモードに移行する。このとき、出力は低出力状態になるように駆動期間が設定される。共振回路の共振周波数は約６０ｋＨｚとなるよう加熱コイル１および共振コンデンサ３を設定し、第１と第２のスイッチング素子４、６の駆動周波数は共振回路の共振周波数の１／３である約２０ｋＨｚとなるようにしている。また、昇圧平滑手段１１は７００Ｖに昇圧平滑するよう動作している。このように第１と第２のスイッチング素子４、６の損失を低減しかつ十分昇圧することでアルミニウムのような低透磁率かつ高導電率である金属も加熱できる高導電率材質モードで動作するようにしているものである。 On the other hand, when it is detected that the load is an aluminum load, when a predetermined drive time ratio is reached, the mode shifts to a mode in which the period of the resonance current is shorter than the drive period of the first switching element 4. At this time, the drive period is set so that the output is in a low output state. The heating coil 1 and the resonance capacitor 3 are set so that the resonance frequency of the resonance circuit is about 60 kHz, and the drive frequency of the first and second switching elements 4 and 6 is about 20 kHz which is 1/3 of the resonance frequency of the resonance circuit. It is trying to become. The step-up / smoothing means 11 operates to step-up / smooth to 700V. In this way, the first and second switching elements 4 and 6 are operated in a high conductivity material mode in which the loss of the first and second switching elements 4 and 6 is reduced and sufficiently boosted to heat a metal having a low magnetic permeability and high conductivity such as aluminum. It is what you are doing.
さらに、アルミニウム系と鉄系の中間材質すなわち非磁性ステンレスの厚板や薄非磁性ステンレス板材の上にアルミニウムや銅などの高導電率材を載置した複合材と検知した場合には第１と第２のスイッチング素子４、６は図２の左側のように駆動する。駆動周波数は共振回路の共振周波数の１／２である約３０ｋＨｚとなるようにして第１のスイッチング素子４を駆動した後半周期の共振電流を流して第１のスイッチング素子４の駆動を停止し、第２のスイッチング素子６の駆動を開始した後、１周期半の共振電流を流して第２のスイッチング素子６の駆動を停止することを繰り返す中間材質モードで動作させる。この時、昇圧平滑手段１１は６００Ｖに昇圧平滑するよう動作していており、駆動周波数は高導電率材質モードより増加しているが第１と第２のスイッチング素子４、６にかかる電圧を高導電率材質モードより低下させることによりスイッチング損失を低減している。 Furthermore, if it is detected as a composite material in which a high conductivity material such as aluminum or copper is placed on an aluminum-based and iron-based intermediate material, that is, a non-magnetic stainless steel plate or a thin non-magnetic stainless steel plate material, The second switching elements 4 and 6 are driven as shown on the left side of FIG. The drive of the first switching element 4 is stopped by flowing a resonance current of the latter half period in which the first switching element 4 is driven so that the driving frequency is about 30 kHz which is 1/2 of the resonance frequency of the resonance circuit, After the driving of the second switching element 6 is started, the operation is performed in the intermediate material mode in which the resonance current of one and a half cycle is supplied and the driving of the second switching element 6 is stopped. At this time, the step-up / smoothing means 11 operates to step-up / smooth to 600 V, and the drive frequency is higher than that in the high conductivity material mode, but the voltage applied to the first and second switching elements 4 and 6 is increased. Switching loss is reduced by lowering the conductivity material mode.
ここで、中間材質モードと判定した負荷２が負荷温度の変化などにより負荷２の特性が高導電率材質と同等にまで変化した場合、負荷材質検知手段１０により中間材質モードから高導電率材質モードに図２のようにインバータの動作を継続させたまま切り替えを行うものである。すなわち第２のスイッチング素子６の駆動を開始した後、１周期半の共振電流を流して第２のスイッチング素子６の駆動を停止した後、第１のスイッチング素子４を駆動した後１周期半の共振電流を流して第１のスイッチング素子４の駆動を停止することを繰り返して中間材質モードから高導電率材質モードに加熱を停止することなくインバータの動作を継続したままで切り替える。 Here, when the load 2 determined to be the intermediate material mode changes to the same level as the high conductivity material due to a change in the load temperature or the like, the load material detection means 10 changes the intermediate material mode to the high conductivity material mode. As shown in FIG. 2, switching is performed while the operation of the inverter is continued. That is, after driving the second switching element 6, a resonance current of one and a half cycles is passed to stop the driving of the second switching element 6, and after driving the first switching element 4, a half cycle The operation of the inverter is continuously switched without stopping the heating from the intermediate material mode to the high conductivity material mode by repeatedly flowing the resonance current and stopping the driving of the first switching element 4.
また、非磁性ステンレス鋼製の鍋など低導電率材質モードと判定した負荷２が負荷温度の変化などにより負荷２の特性が中間材質と同等にまで変化した場合、負荷材質検知手段１０により低導電率材質モードから中間材質モードに図２のようにインバータの動作を継続させたまま切り替えを行うものである。すなわち第２のスイッチング素子６の駆動を開始した後、半周期の共振電流を流して第２のスイッチング素子６の駆動を停止した後、第１のスイッチング素子４を駆動した後半周期の共振電流を流して第１のスイッチング素子４の駆動を停止し第２のスイッチング素子６の駆動を開始した後、半周期の共振電流を流して第２のスイッチング素子６の駆動を停止することを繰り返して低導電率材質モードから中間材質モードに加熱を停止することなくインバータの動作を継続したままで切り替える。 Further, when the load 2 determined to be in the low conductivity material mode, such as a non-magnetic stainless steel pan, changes to the same level as the intermediate material due to a change in the load temperature or the like, the load material detection means 10 reduces the low conductivity. Switching from the rate material mode to the intermediate material mode is performed while the operation of the inverter is continued as shown in FIG. That is, after starting the driving of the second switching element 6, a half-cycle resonance current is supplied to stop the driving of the second switching element 6, and then the second-cycle resonance current driving the first switching element 4 is changed. The first switching element 4 is stopped to drive and the second switching element 6 is started to drive, and then the half-cycle resonance current is supplied to stop the driving of the second switching element 6. Switching from the conductivity material mode to the intermediate material mode is performed while the operation of the inverter is continued without stopping the heating.
以上述べたように、本実施の形態では駆動周期内に第１のスイッチング素子４の駆動期間内に半周期以内の共振電流を流し、第２のスイッチング素子６の駆動期間内に１周期以上の共振電流を流す信号を出力してなる中間材質モードを有し負荷検知結果に応じてモードを切り替える構成としているので、容易な構成で中間材質の負荷もより大きな出力で誘導加熱できるとともに高導電率から低導電率まで負荷の材質に応じて加熱モードを切り替えることができることからより加熱出力を大きくすることができるとともに、加熱モードの切り替えを加熱を停止することなく連続して加熱を継続できる。 As described above, in the present embodiment, a resonance current within a half cycle is caused to flow within the driving period of the first switching element 4 within the driving period, and one period or more is required within the driving period of the second switching element 6. Since it has an intermediate material mode that outputs a signal that flows a resonance current and switches the mode according to the load detection result, the load of the intermediate material can be induction heated with a larger output with a simple structure and high conductivity Since the heating mode can be switched according to the material of the load from low to low conductivity, the heating output can be increased, and the heating can be continuously switched without stopping the heating.
また、本実施の形態では第１のスイッチング素子４の駆動期間内に半周期以内の共振電流を流し、第２のスイッチング素子６の駆動期間内に１周期以上の共振電流を流すとしたが、第２のスイッチング素子６の駆動期間内に半周期以内の共振電流を流し、第１のスイッチング素子４の駆動期間内に１周期以上の共振電流を流すとしても同様の効果が得られる。 Further, in the present embodiment, a resonance current within a half cycle is caused to flow within the driving period of the first switching element 4 and a resonance current of one period or more is caused to flow within the driving period of the second switching element 6. The same effect can be obtained if a resonance current within a half cycle is caused to flow within the driving period of the second switching element 6 and a resonance current of one period or more is caused to flow within the driving period of the first switching element 4.
また、本実施の形態では中間材質モードから高導電率材質モードへ切替を行ったが高導電率材質モードから中間材質モードへの切替も行えることはいうまでもない。 In the present embodiment, the intermediate material mode is switched to the high conductivity material mode, but it goes without saying that the high conductivity material mode can be switched to the intermediate material mode.
さらに、負荷材質検知手段１０を加熱コイル１電流検知によるものあるいは共振コンデンサ３電圧検知によるものとしても第１と第２のスイッチング素子４、６の電流増大の検知は可能でありより容易な構成で負荷材質検知を行い加熱モードを切り替えることができる。 Further, even if the load material detection means 10 is based on the heating coil 1 current detection or the resonance capacitor 3 voltage detection, it is possible to detect the current increase in the first and second switching elements 4 and 6 and to make the configuration easier. The load material can be detected and the heating mode can be switched.
また、図４の本発明の別の実施の形態における誘導加熱装置に示すように、共振コンデンサの切替手段（リレー２０）を設けて共振コンデンサ３容量を変更する（並列に補正用共振コンデンサ１９を接続する）ことと組み合わせて加熱モード切替を行う、すなわち加熱を停止して共振コンデンサ容量を変更する加熱モード切替を行うのと前述の加熱を停止することなく連続して継続しながら加熱モード切替を行うのとを併用すればさらに負荷２の材質適用範囲の広い誘導加熱装置とすることができる。 Further, as shown in the induction heating apparatus in another embodiment of the present invention shown in FIG. 4, the resonance capacitor switching means (relay 20) is provided to change the capacity of the resonance capacitor 3 (the correction resonance capacitor 19 is connected in parallel). Switching the heating mode in combination with the connection), that is, the heating mode switching for changing the resonance capacitor capacity by stopping the heating and the heating mode switching while continuing without stopping the heating described above. If used together, an induction heating device with a wider material application range of the load 2 can be obtained.
以上のように、本発明にかかる誘導加熱装置は、導電率の異なる材質の負荷に応じて加熱出力を大きくすることが可能となるので、複数の導電率の異なる材料を加熱する工業用誘導加熱等の用途にも適用できる。 As described above, the induction heating device according to the present invention can increase the heating output in accordance with the load of the material having different conductivity. Therefore, the industrial induction heating for heating a plurality of materials having different conductivity. It can also be applied to other uses.
１ 加熱コイル
２ 負荷
３ 共振コンデンサ
４ 第１のスイッチング素子
５ 第１の逆導通素子
６ 第２のスイッチング素子
７ 第２の逆導通素子
８ インバータ
９ 制御回路
１０ 負荷材質検知手段
１１ 昇圧平滑手段
DESCRIPTION OF SYMBOLS 1 Heating coil 2 Load 3 Resonance capacitor 4 1st switching element 5 1st reverse conducting element 6 2nd switching element 7 2nd reverse conducting element 8 Inverter 9 Control circuit 10 Load material detection means 11 Boosting smoothing means
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2009087796A (en) * | 2007-10-01 | 2009-04-23 | Tama Tlo Kk | Induction heating apparatus |
| JP2011071004A (en) * | 2009-09-28 | 2011-04-07 | Panasonic Corp | Induction heating cooker |
| JP2016058176A (en) * | 2014-09-08 | 2016-04-21 | パナソニックＩｐマネジメント株式会社 | Induction heating device |
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| JP2009087796A (en) * | 2007-10-01 | 2009-04-23 | Tama Tlo Kk | Induction heating apparatus |
| JP2011071004A (en) * | 2009-09-28 | 2011-04-07 | Panasonic Corp | Induction heating cooker |
| JP2016058176A (en) * | 2014-09-08 | 2016-04-21 | パナソニックＩｐマネジメント株式会社 | Induction heating device |
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