中频加热炉（翻译了一小段）

大刀刀

鸟文：
Introduction
Induction heating is a non-contact heating process. It uses high frequency electricity to heat materials that are electrically conductive. Since it is non-contact, the heating process does not contaminate the material being heated. It is also very efficient since the heat is actually generated inside the work piece. This can be contrasted with other heating methods where heat is generated in aflame or heating element, which is then applied to the work piece. For these reasons Induction Heating lends itself to some unique applications in industry.
How does Induction Heating work ?
A source of high frequency electricity is used to drive a large alternating current through a coil. This coil is known as the work coil. See the
Picture opposite.
The passage of current through this coil generates a very intense and rapidly changing magnetic field in the space within the work coil.The workpiece to be heated is placed within this intense alternating magnetic field.
Depending on the nature of the work piece material, a number of things happen...
The alternating magnetic field induces a current flow in the conductive workpiece. The arrangement of the work coil and theworkpiece can be thought of as an electrical transformer. The work coils like the primary where
Electrical energy is fed in, and theworkpiece is like a single turn secondary that is short-circuited. This causes tremendous currents to flow through the workpiece. These are known as eddy currents.
In addition to this, the high frequency used in induction heating applications gives rise to a phenomenon called skin effect. This skin effect forces the alternating current to flow in a thin layer to wards the surface of the work piece. The skin effect increases the effectiveness is trance of the
metal to the passage of the large current. Therefore it greatly increases
the heating effect caused by the current induced in the workpiece.
And for Ferrous metals ?
For ferrous metals like iron and some types of steel, there is an additional heating mechanism that takes place at the same time as the eddy currents
mentioned above. The intense alternating magnetic field inside the work
coil repeatedly magnetizes and de-magnetizes the iron crystals. This rapid flipping of the magnetic domains causes considerable friction and heating
inside the material. Heating due to this mechanism is known as Hysteresis loss, and is greatest for materials that have a large area inside their B-Hcurve. This can be a large contributing factor to the heat generated during induction heating, but only takes place inside ferrous materials. For this reason ferrous materials lend themselves more easily to heating by induction than non-ferrous materials.
It is interesting to note that steel looses its magnetic materials when
heated above approximately 700°C. This temperature is known as the Curie  temperature. This means that above 700°C there can be no heating   of the material due to hysteretic losses. Any further heating of the material must be due to induced eddy currents alone. This makes heating steel above 700°C more of a challenge for the induction heating systems. The fact that Copper and Aluminium are both non-magnetic and very good electrical conductors can also make these materials challenge to heat efficiently. (We will
See that the best course of action for these materials is to up the
frequency to exaggerate losses due to the skin effect.)
What is Induction Heating used for ?
Induction heating can be used for any application where we want to heat an electrically conductive material in a clean, efficient and controlled manner.
One of the most common applications is for sealing the anti-tamper seals that are stuck to the top of medicine and drinks bottles. A foil seal coated with "hot-melt glue" is inserted into the plastic cap and screwed onto the top of each bottle during manufacture. These foil seals are then rapidly heated as the bottles pass under an induction heater on the production line. The heat generated melts the glue and seals the foil onto the top of the bottle. When the cap is removed, the foil remains providing an airtight seal and preventing any tampering or contamination of the bottle's contents until the customer pierces the foil.
Another common application is "getter firing" to remove contamination from evacuated tubes such as TV picture tubes, vacuum tubes, and various gas discharge lamps. A ring of conductive material called a "getter" is placed inside the evacuated glass vessel. Since induction heating is a non-contact process it can be used to heat the getter that is already sealed inside a vessel. An induction work coils located close to the getter on the outside of the vacuum tube and the AC source is turned on. Within seconds of starting the induction heater, the getter is heated white hot, and chemicals in its coating react with any gasses in the vacuum. The result is that the getter absorbs any last remaining traces of gas inside the vacuum tube and increases the purity of the vacuum.
Yet another common application for induction heating is a process called Zone purification used in the semiconductor manufacturing industry. This is a process in which silicon is purified by means of a moving zone of molten material. An Internet Search is sure to turn up more details on this process that I know little about.
Other applications include melting, welding and brazing or metals. Induction cooking hobs and rice cookers. Metal hardening of ammunition, gear teeth, saw blades and drive shafts, etc are also common applications because the induction process heats the surface of the metal very rapidly. Therefore it can be used for surface hardening, and hardening of localized areas of metallic parts by "outrunning" the thermal conduction of heat deeper into the part or to surrounding areas. The non contact nature of induction heating also means that it can be used to sterilize metal instruments by heating them to high temperatures whilst they are already sealed inside a known sterile environment in order to kill germs.
What is required for Induction Heating ?
In theory only 3 things are essential to implement induction heating:
1.        A source of High Frequency electrical power,
2.        A work coil to generate the alternating magnetic field,
3.        An electrically conductive work piece to be heated,
Having said this, practical induction heating systems are usually a little more complex. For example, a matching network is often required between the High Frequency source and the work coil in order to get good power transfer. Water cooling systems are also common in high power induction heaters to remove waste heat from the work coil and its matching network. Finally some control electronics is usually employed to control the intensity of the heating action, ensure consistent results, and to protect the system from
adverse operating conditions. However, the basic principle of operation of any induction heater remains the same as described earlier.

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Practical implementation
In practice the work coil is usually incorporated into a resonant tank circuit. This has a number of advantages. Firstly, it makes either the current or the voltage become sinusoidal. This minimizes losses in the inverter by allowing it to benefit from either zero-voltage-switching or zero-current-switching depending on the exact arrangement chosen. The sinusoidal waveform at the work coil also represents a more pure signal and causes less Radio Frequency Interference to nearby equipment. We will see that there are a numberof resonant schemes that the designer of an induction heater can choosefor the work coil:
Series resonant tank circuit
The work coil is made to resonate at the intended operatingfrequency by means of a capacitor placed in series with it. This causesthe current through the work coil to be sinusoidal. The seriesresonance also magnifies the voltage across the work coil, far higherthan the output voltage of the inverter alone. The inverter sees asinusoidal load current but it must carry the full current that flowsin the work coil. For this reason the work coil often consists of manyturns of wire with only a few amps or tens of amps flowing.
This arrangement is commonly used in things like rice cookers wherethe power level is low, and the inverter is located next to the objectto be heated. The main drawbacks of the series resonant arrangement arethat the inverter must carry the same current that flows in the workcoil. In addition to this the series resonant action can become verypronounced if there is no workpiece present to damp the circuit. Thisis not a problem in applications like rice cookers where the workpieceis always the same cooking vessel, and its properties are well known atthe time of design.
The tank capacitor is typically rated for a high voltage because ofthe resonant voltage rise experienced in the series tuned resonantcircuit.
Parallel resonant tank circuit
The work coil is made to resonate at the intended operatingfrequency by means of a capacitor placed in parallel with it. Thiscauses the current through the work coil to be sinusoidal. The parallelresonance also magnifies the current through the work coil, far higherthan the current capability of the inverter alone. The inverter sees asinusoidal load current. However, in this case it only has to carry thepart of the load current that actually does real work. The inverterdoes not have to carry the full circulating current in the work coil.This means that the work coil can be placed at a location remote fromthe inverter without incurring massive losses in the feed wires.
It also means that work coils using this technique often consist offew turns of a thick copper conductor but with large currents of manytens or hundreds of amps flowing. (This is necessary to get therequired Ampere turns to do the induction heating.) Water cooling iscommon for all but the smallest of systems. This is needed to removeexcess heat generated by the passage of the large high frequencycurrent through the work coil and its associated tank capacitor.
In the parallel resonant tank circuit the work coil can be thoughtof as an inductive load with a "power factor correction" capacitorinstalled across it. The PFC capacitor provides reactive current flowequal and opposite to the inductive current drawn by the work coil.Therefore the only current flow from the inverter is a small amountrequired to overcome losses in the "PFC" capacitor and the work coil.There is always some loss in this tank circuit due to dielectric lossin the capacitor and skin effect causing resistive losses in the workcoil. Therefore a small current is always drawn from the inverter. Whena lossy workpiece is inserted into the work coil, this damps theparallel resonant circuit by introducing a further loss into thesystem. Therefore the current drawn by the parallel resonant tankcircuit increases when a workpiece is entered into the coil.
Impedance matching
Or simply "Matching". This refers to the electronics that sitsbetween the source of high frequency power and the work coil we areusing for heating. In order to heat a solid piece of metal viainduction heating we need to cause a TREMENDOUS current to flowin the surface of the metal. However this can be contrasted with theinverter that generates the high frequency power. The invertergenerally works better (and the design is somewhat easier) if itoperates at fairly high voltage but a low current. This allows commonswitch mode MOSFETs to be used. The comparatively low currents alsomake the inverter less sensitive to layout and stray inductance. It isthe job of the matching network and the work coil to transform the highvoltage/low current from the inverter to the low voltage/high currentrequired to heat the workpiece efficiently.
We can think of the tank circuit incorporating the work coil (Lw) and its capacitor (Cw) as a parallel resonant circuit.
This has a resistance (R) due to the lossy workpiece coupled intothe work coil due to the magnetic coupling between the two conductors.
See the schematic opposite.
In practice the resistance of the work coil, the resistance of thetank capacitor, and the resistance of the workpiece all introduce aloss into the tank circuit and damp the resonance. Therefore it isuseful to combine all of these losses into a single "loss resistance."In the case of a parallel resonant circuit this loss resistance appearsdirectly across the tank circuit. This resistance represents the onlycomponent that can consume power, and therefore we can think of thisloss resistance as the load that we are trying to drive power into asefficiently as possible. When driven at resonance the current drawn by the tank capacitor andthe work coil are equal and opposite in phase and therefore cancel eachother out as far as the source of power is concerned. This meansthat the only load presented to the power source at the resonantfrequency is the loss resistance across the tank circuit.  (Notethat, when driven either side of the resonant frequency, there is anadditional "out-of-phase" component to the current caused by incompletecancellation of the work coil current and the tank cap current. Thisreactive current increases the total magnitude of the current beingdrawn from the source but does not contribute to any useful heating inthe workpiece.)
The job of the matching network is simply to transform thisrelatively large loss resistance across the tank circuit down to alower value that better suits the inverter attempting to drive it.There are many different ways to achieve this impedance transformationincluding tapping the work coil, using a ferrite transformer, acapacitive divider in place of the tank capacitor, or a matchingcircuit such as an L-match network.
In the case of an L-match network it can transform the relativelyhigh load resistance of the tank circuit down to something around 10ohms which better suits the inverter. This figure allows the inverterto run from several hundred volts whilst keeping currents down to areasonable level so that standard switch-mode MOSFETs can be used toperform the switching operation.
The L-match network consists of components Lm and Cm shown opposite.
The L-match network also has another highly desirable property. TheL-match network provides a progressively rising inductive reactance toall frequencies higher than the resonant frequency of the tank circuit.This is very important when the work coil is to be fed from an inverterthat generates a squarewave voltage output. Here is an explanation ofwhy this is so…
The squarewave voltage generated by most half-bridge and full-bridgecircuits is rich in high frequency harmonics as well as the wantedfundamental frequency. Direct connection of such a voltage source to aparallel resonant circuit would cause excessive currents to flow at theharmonics of the drive frequency! This is because the tank capacitor inthe parallel resonant circuit presents a progressively lower capacitivereactance to increasing frequencies. This is potentially very damagingto a voltage-source inverter. It results in large current spikes at theswitching transitions as the inverter tries to rapidly charge anddischarge the tank capacitor on rising and falling edges of thesquarewave. The inclusion of the L-match network between the inverterand the tank circuit negates this problem. Now the output of theinverter sees the inductive reactance of Lm in the matching networkfirst, and all harmonics see a gradually rising inductive impedance.
In summary, the inclusion of an L-match network between the inverter and the parallel resonant tank circuit achieves two things.
1.        Impedance matching so that the required amount of power can be supplied from the inverter to the workpiece,
2.        Presentation of a rising inductive reactance to high frequency harmonics to keep the inverter safe and happy.
Looking at the previous schematic above we can see that thecapacitor in the matching network (Cm) and the tank capacitor (Cw) areboth in parallel. In practice both of these functions are usuallyaccomplished by a single capacitor. Most of its capacitance can bethought of as being in parallel resonance with the work coil, with asmall amount providing the impedance matching action with the matchinginductor (Lm.) Combing these two capacitances into one leads us toarrive at the LCLR model for the work coil arrangement, which iscommonly used in industry.
The LCLR work coil
This arrangement incorporates the work coil into a parallel resonantcircuit and uses the L-match network between the tank circuit and theinverter. The matching network is used to make the tank circuit appearas a more suitable load to the inverter, and its derivation isdiscussed in the section above.

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The LCLR work coil has a number of desirable properties:
1.        A huge current flows in the work coil, but the inverter only has tosupply a low current. The large circulating current is confined to thework coil and its parallel capacitor, which are usually located closeto each other.
2.        Only low current flows along the transmission line from the inverter to the tank circuit, so this can use lighter duty cable.
3.        Any stray inductance of the transmission line becomes part of the matching network inductance (Lm.)
4.        The inverter sees a sinusoidal load current so it can benefit fromZCS or ZVS to reduce its switching losses and therefore run cooler.
5.        The series matching inductor can be altered to cater for different loads placed inside the work coil.
6.        The tank circuit can be fed via several matching inductors frommany inverters to reach power levels above those achievable with asingle inverter. The matching inductors provide inherent sharing of theload current between the inverters and also make the system tolerant tosome mismatching in the switching instants of the paralleled inverters.
Another advantage of the LCLR work coil arrangement is that it doesnot require a high-frequency transformer to provide the impedancematching function. Ferrite transformers capable of handling severalkilowatts are large, heavy and quite expensive. In addition to this,the transformer must be cooled to remove excess heat generated by thehigh currents flowing in its conductor. The incorporation of theL-match network into the LCLR work coil arrangement removes thenecessity of a transformer to match the inverter to the work coil,saving cost and simplifying the design.
However, the designer should appreciate that a 1:1 isolatingtransformer may still be required between the inverter and the input tothe LCLR work coil arrangement if electrical isolation is necessaryfrom the mains supply. It depends whether isolation is important, andwhether the PSU in the induction heater already provides sufficientelectrical isolation to meet these requirements.
Complete schematic
The complete schematic showing the inverter driving its LCLR work coil arrangement is shown below.
Note that this schematic DOES NOT SHOW the MOSFET gate-drive and control electronics! Please dont ask for further information.
The inverter is a simple half-bridge consisting of two MTW14N50MOSFETs made my On-semiconductor (formerly Motorola.) It is fed from asmoothed DC supply with decoupling capacitor across the rails tosupport the AC current demands of the inverter. However, it should berealised that the quality and regulation of the power supply forinduction heating applications is not critical. Full-wave rectified(un-smoothed) mains can work equally as well as smoothed and regulatedDC when it comes to heating metal. And there are many arguments forkeeping the size of the DC bus capacitor down to a minimum. Inparticular it improves the power factor of current drawn from the mainsupply, and it also minimises stored energy in case of fault conditionswithin the inverter.
The DC blocking capacitor is merely to block the DC output from thehalf-bridge inverter from causing current flow through the work coil.It is sized sufficiently large that it does not take part in theimpedance matching, and does not adversely effect the operation of theLCLR work coil arrangement.
Fault tolerance
The LCLR work coil arrangement is very well behaved under a variety of possible fault conditions.
1.        Open circuit work coil.
2.        Short circuit work coil, (or tank capacitor.)
3.        Shorted turn in work coil.
4.        Open circuit tank capacitor.
All of these failures result in an increase in the impedance beingpresented to the inverter and therefore a corresponding drop in thecurrent drawn from the inverter. The author has personally used ascrewdriver to short-circuit between turns of a work coil carryingseveral hundred amps. Despite sparks flying at the location of theapplied short-circuit, the load on the inverter is reduced and thesystem survives this treatment with ease.
The worst thing that can happen is that the tank circuit becomesdetuned such that its natural resonant frequency is just above theoperating frequency of the inverter. Since the drive frequency is stillclose to resonance there is still significant current flow out of theinverter. But the power factor is reduced due to the detuning, and thecurrent begins to lead the voltage. This situation is undesirablebecause the load current seen by the inverter changes direction beforethe applied voltage changes sign. The outcome of this is that currentis force-commutated between free-wheel diodes and the opposing MOSFETevery time the MOSFET is turned on. This causes a forced reverserecovery of the free-wheel diodes whilst they are carrying significantforward current. This results in a large current surge through both thediode and the opposing MOSFET that is turning on.
Whilst not a problem for special fast recovery rectifiers, thisforced recovery can cause problems if the MOSFETs intrinsic body diodesare used to provide the free-wheel diode function. However, it shouldbe realised that proper control of the inverter operating frequencyshould ensure that it tracks the resonant frequency of the tankcircuit. Therefore the leading power factor condition should ideallynot arise, and should certainly not persist for any length of time. Theresonant frequency should be tracked up to its limit, then the systemshut-down if it has wandered outside of an acceptable range.
Power control methods
It is often desirable to control the amount of power processed by aninduction heater. This determines the rate at which heat energy istransferred to the workpiece. The power setting of this type ofinduction heater can be controlled in a number of different ways:
1. Varying the DC link voltage.
The power processed by the inverter can be decreased by reducing thesupply voltage to the inverter. This can be done by running theinverter from a variable voltage DC supply such as a controlledrectifier using thyristors to vary the DC supply voltage derived fromthe mains supply. The impedance presented to the inverter is largelyconstant with varying power level, so the power throughput of theinverter is roughly proportional to the square of the supply voltage.Varying the DC link voltage allows full control of the power from 0% to100%.
2. Varying the duty ratio of the devices in the inverter.
The power processed by the inverter can be decreased by reducing theon-time of the switches in the inverter. Power is only sourced to thework coil in the time that the devices are switched on. The loadcurrent is left to freewheel through the devices body diodes during thedeadtime when both devices are turned off. Varying the duty ratio ofthe switches allows full control of the power from 0% to 100%. The onlysignificant drawback is forced reverse recovery of the free-wheeldiodes that can occur when the duty ratio is reduced.
3. Varying the operating frequency of the inverter.
The power supplied by the inverter to the work coil can be reducedby detuning the inverter from the natural resonant frequency of thetank circuit incorporating the work coil. As the operating frequency ofthe inverter is moved away from the resonant frquency of the tankcircuit, there is less resonant rise in the tank circuit, and thecurrent in the work coil diminishes. Therefore less circulating currentis induced in the workpiece.

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In order to control the power the inverter is normally detuned onthe high frequency side of the tank circuits natural resonance. Thiscauses the inductive reactance of the matching circuit to becomedominant as the frequency increases. Therefore the current drawn fromthe inverter by the matching network starts to lag in phase anddiminish in amplitude. Both of these factors contribute to a reductionin real power throughput. In addition to this the lagging power factorensures that the devices in the inverter still turn on with zerovoltage across them.
This method of controlling power level by detuning is very simplesince most induction heaters already have control over the operatingfrequency of the inverter in order to cater for different workpiecesand work coils. The downside is that it only provides a limited rangeof control, as there is a limit to how fast power semiconductors can bemade to switch. This is particularly true in high power applicationswhere the devices may be running close to maximum switching speedsanyway.
4. Varying the value of the inductor in the matching network.
The power supplied by the inverter to the work coil can be varied byaltering the value of the matching network components. The L-matchnetwork between the inverter and the tank circuit technically consistsof an inductive and a capacitive part. But the capacitive part is inparallel with the work coil's own tank capacitor, and in practice theseare usually one and the same part. Therefore the only part of thematching network that is available to make adjustable is the inductor.
The matching network is responsible for transforming the load of theworkcoil to a suitable load impedance to be driven by the inverter.Altering the inductance of the matching inductor adjusts the value towhich the load impedance is translated. In general, decreasing theinductance of the matching inductor causes the work coil impedance tobe transformed down to a lower impedance. This lower load impedancebeing presented to the inverter causes more power to be sourced fromthe inverter. Conversely, increasing the inductance of the matchinginductor causes a higher load impedance to be presented to theinverter. This lighter load results in a lower power flow.
The degree of power control achieveable by altering the matchinginductor is fairly small. There is a also a shift in the resonantfrequency of the overall system. This is the price to pay for combiningthe L-match capacitance and tank capacitance into one unit. The L-matchnetwork essentially borrows some of the capacitance from the tankcapacitor to perform the matching operation, thus leaving the tankcircuit to resonate at a higher frequency. For this reason the matchinginductor is usually fixed or adjusted in coarse steps to suit theintended workpiece to be heated, rather than provide the user with afully adjustable power setting.

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导言
感应加热是一个没有接触的加热方式，它是一个用高频的电流对物品进行加热的过程。应为他是无接触的，所以对加热物品不会造成污染。他对半成品加工非常有效，比其他热加工方式要好的多，并被广泛运用于工业生产中半成品的加工。
     感应加热如何工作的呢？
     通过（线圈的）缠绕使交互式的电流产生高频震荡。这个工作线圈看起来好像是相互对立的。在工作线圈中间，通过电流可以产生一个剧烈并且飞速变化的磁场。放置在线圈中间的工件就会被一个交互式的磁场加热。依靠这种方式，工件被不停的加热。。。一个交互式的磁场导致电流的运动通过传导来给工件加热。被加热工件还要靠变压器来完成。这个工件的加工要靠电能的反馈，就像电流被短路了一样。这样，就使工件被巨大的旋转电流所包围和穿透。除此以外，这种感应现象也被称为表面效应。表面效应能使交互式的电流集中作用在工件表面。表面效应也可以产生强大的电流通道。所以，可以通过感应式加热来满足被加工工件的热处理的要求。
和黑色金属（铁类）
许多黑色金属像铁一样可以通过感应涡流这样的外加设备（将其加热到适宜的温度）。在工作线圈中产生强大的交互式磁场，使得（线圈中）的工件的晶体被磁化的同时被消磁。这个飞速变化的磁畴在工件内产生了相当可观的热量。（产生的）热量被认为是在工件中的磁滞现象，并且与原料内大面积的布氏硬度（有关）。这个夸张的因素在于感应加热期间热量的产生，但仅限于含铁的原料而不含铁的原料不能自身被（交互式的磁场）加热。
  钢铁在磁场中（通过以上办法）可以轻松地被加热到700℃以上，这个温度就是著名的“居里温度”。由于每平方米的热损失使原料很难被加热到700℃以上。而涡流电流的产生就成了（将原料加热到700℃）独一无二的方法。加热的钢铁高于700℃是对感应式加热系统的一个挑战，事实上，铜和铝这些无磁性的材料被制成（加热原件）是对感应式加热提高效率的一种挑战。（我们将领会由于表面效应而导致金属温升的频率的变化）

感应加热的应用
感应加热可以广泛的运用与不含杂质的任何导电物质是直接有效的控制方式。通用运用最多的是药瓶的瓶盖铅封和饮料罐。在制造业中（用于）用热熔胶的密封底漆封塑料瓶口的瓶帽儿的金属锡箔，这些金属锡箔在生产线上被感应式加热设备迅速贴在瓶口。这些金属箔片和胶被感应式加热软化后贴在瓶口。这些胶和金属箔片能够起到防止污染物进入药瓶直到消费者刺破瓶口。
另一个用途是“getter firing”（烘烤获得者），去生产诸如电视机显像管、真空电子管和气体放电管。一个环状的传导材料被称为“getter”（收获者）被放置在一个抽空的玻璃容器里。感应式加热被用于的抽空玻璃容器的无接触式密封热处理。（就是真空管抽空后的热封口处理）感应式工作线圈的另一个用途是定位于真空管和交流电开关的生产。电感应加热器的第二个用途是可以保证真空管内的气体的残留量到最小。（此段很长，直译不了）。
另外感应式加热的另一个用途在于工业用半导体的提纯。这个过程是用移动的圈使熔铸的硅元素得到提纯。你可以从互联网上找到详尽的资料，但我只知道一点点。
另一种应用方式是融化，用于定位焊接和金属钎焊，烹调铁架和蒸锅。淬水的金属有军火、齿轮、锯条和传动轴应为感应式加热可以迅速的加热其金属表面，因此，它可以用于金属表面金属的硬化。金属的局部淬水可以热量传导到周围其他部位，非接触的感应式加热方式可以用高温来杀死病菌达到消毒金属器皿的目的。
什么是感应式加热所必需的？
理论上，感应式加热只需要3个部件。
1．        一个高频的电源。
2．        一个可以产生交互式磁场的工作线圈。
3．        一个可以加热的工件。
综上所述，感应式加热能够用于很多领域，例如，一个匹配网络在两端必须有高频源并且工作线圈是为了更好的传递（信息）。水冷系统是为了能够移走工作线圈所产生的热量，相应的电力控制是为了控制感应加热量以确保有一致的结果并且有相应的保护系统。无论如何，一些感应加热的基本工作原理和早期的描述是一样的。
实际操作
一个工作线圈通常由一个就谐振回路组成。它有许多的优势。首先，电压为正弦曲线，容易获得，由于零电流和零电压精确的相互转换可以使能量损失降到最小。工作线圈的电压的正弦曲线的特性可以对周围设备的无线干扰较低。我们可以在设计师那里找到共鸣。
串联谐振电路：

大刀刀

本人英语水平较差，上面的汉字我翻译了数天，本想善始善终。但终于放弃了！

990147

支持LZ~~请再接再厉

lulu007

辛苦了 加油

zabc

最关键的是电源部分

ms1175555

完全没能力，做出来。