Page 3 : 簡易電路 (續) Simple Circuits - Continued

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原文: http://www.totallyamped.net/adams/page3.html

在這一頁，我們終於要從驅動線圈收集 CEMF了。下面的 Fig 7 要介紹更為成熟的控制電路，會用到 Voltage Regulator 以及用 Mosfet 來做開關。 The circuit also introduces a CEMF output and two different paths in which it can be connected. 其中一個 path 通常稱為 "Fly-Back"，而另一個 path 用 "Fly-Forward" 來描述是不錯的。Fly-Back 實質上是在驅動線圈關閉時用來收回儲存在驅動線圈的一些能量的方式。一般而言，假如 Fly-Back 電路連接到另一個電池，此馬達將會持續運轉，不會損失任何轉矩或轉速，但是它只能對第二個電池充電，且其充電速率低於電源電池的放電速率。能夠回復的電流最多大約只能達到驅動電流的 25-30 %。然而這真的是個回收的 path，因為和不接上此電路比起來，這樣並不會使驅動電路消耗更多的電流。

假如你用此 Fly-Back path 來對尚未充電的電解電容充電，那麼剛開始馬達會變慢，而且消耗更多的電流，直到電容器的電壓爬昇至與線圈兩端所測量到的順向電壓相同。實際上，假如第二顆電池的快沒電了而且它的電壓顯著的低於電源電池，也會如此。一旦電池或是電容器的電壓達到和順向線圈電壓一樣，那麼對驅動電路就不再有不良的影響，可以不用為回收電流而付出待價。

很多人會這樣想，假如電路產生的 Voltage spike 很大，那麼回收的電流一定會比消耗的還多。答案是不會。假如他們真的量到非常大的 Current spikes，那他們就真的是碰到令人難以置信的事了!!!；而我也會真的很想知道這回事!!! 但是產生CEMP的 collapsing magnetic field不會產生很大的 Current spike，只會產生很大的 Voltage spike。很大的 Voltage spike 通常對電池和電路元件的負面影響還大於正面的作用。

Fly-Forward is simply a different way of directing the CEMF through the circuit. It acts like a current pump because it adds the CEMF to the supply battery EMF in series with each other and can be used to charge a secondary Battery (or Capacitor) at a much higher rate than Fly-Back. But it will severely inhibit motor running speed and torque, and the Current drawn from the supply will increase dramatically. In essence Fly-Forward is a method of stepping up DC to a higher DC value without the use of Transformers and the need to convert DC to AC before stepping up through a transformer can occur. When connecting the circuit to utilize Fly-Forward, the coil doesn't actually experience a time when there is no Current flowing through it, (unless the operational duty cycle(on time) is very low) even when the drive Transistor or Mosfet is turned off. Instead the coil experiences a state of "low Current" when the drive circuit is "on" and a state of "high Current" when the drive circuit is "off". 在 Fly-Back 和 Fly-Forward 兩種情況中，都無法得到額外的 free energy。

利用 Fly-Back 可以想成是降低馬達的整體功率消耗的方式，因為它會在兩個脈衝之間回收儲存在線圈的能量，將其傾倒至第二顆電池以供稍後重複使用。在驅動線圈上使用 bi-filar windings，也可以在兩個順向電流脈衝之間，將儲存的能量直接傾倒至電源電池。我將在後面的 page 討論不同的線圈設計。請注意，假如電池連接至 Fly-Forward path，那麼 Fly-Back path 就不再有 CEMF 可用了。換句話說，在同一時間，不可能同時從兩個 path 收集電流。參見下面的 Fig 7 來解釋 Mosfet 電路的運作及 Fly-Back 和 Fly-Forward path。

In Fig 7 above, the Hall IC supply circuit is fed via a Voltage regulator that can be a fixed output voltage type or a variable output voltage depending on the type of regulator used. If using a fixed output type, it still may be necessary to incorporate a resistor or diodes in series with the Hall IC supply to achieve the desired voltage range necessary (in conjunction with VR1) to turn the Mosfet MQ1 on and off. In this circuit there are three Mosfets which are hooked up in a "flip flop" arrangement to turn the drive circuit on or off. Why go to all this trouble of adding extra components? Well Mosfets are Voltage controlled not Current controlled, though they do still require a small amount of current to turn on. Like Transistors they will turn on at at .6 Volts but if the Gate to Sink junction (equivalent to base-emitter junction of a transistor) is fed a voltage of 10Volts or more, then the Source to Sink junction (equivalent to collector-emitter junction of a transistor) will have a resistive value of .001 or less ohms, which is very nearly zero resistance. This makes Mosfets ideal for pulse generating and DC motor control circuits, and indeed, is generally what they are used for.

If Mosfets are fed 10Volts or more to the Gate (base), they will have almost nil voltage drop across the Source to Sink junction, and very little heat will be created within the Mosfet, and hence miniscule heat losses are incurred. Because the Gate to Sink junction current requirement is in the high micro-amp range (below milli-amp range), then a few extra components will only introduce micro-amp Current losses. Now lets look at how the circuit achieves the switching and provides a higher Voltage to the Gate of the drive Mosfet MQ3.

當 Hall IC 為 "on" 時，MQ1 也會 on，但 MQ2 的 Gate Voltage 是由10K ohm 的 R2 與 MQ1 的 Source 接點所決定。此電壓不會高於 .6V，因為 MQ1 Source 至 Sink 的 Junction 為 on。流入 MQ2 的 Gate 的電流目前只有 60 micro-amps，所以在作用上會使 MQ2 保持 off。同樣的，驅動 Mosfet MQ3 的 Gate，是由 R3 與 MQ2 的Source 接點所決定。因為 MQ2為 off，所以 MQ2 的 Source 至 Sink 的 junction 在作用上為開路的，使得 MQ2 的 Source 的電壓很接近電源的電壓，而 MQ2 的 Source 連接至 MQ3 的 Gate，但此電流會被10K 的 R3 限制住。假設 MQ3 的 Gate電壓為10V，則其電流為 10V 除以 10K ohms(R3)，其為 1 milli-amp or 1000 micro-amps，其大小足以確保 MQ3 導通。

當 Hall IC 變為 "off" 時，MQ1 也變為 off，其使得至 MQ2 Gate 的電壓很接近電源的電壓，因而 MQ2 變為 on。 當 MQ2 變為 on 時，MQ3 的 Gate 的電壓掉落至 .6V，因其電流只有 60 micro-amps，因而MQ3變成 off。因為 Mosfet 的 on/off 切換時間非常的快，所以產生的脈波非常 sharp 和 clean。請注意，在MQ3 的 Gate 與地之間有一個100K ohm 的電阻 (R4)。因為 Mosfets 的 Gate 至 Sink 有非常高的阻抗，所以在 Source 至 Sink (driving) 的電路的突然而且電壓很大的變動返饋至電源，變成很大的voltage spike時，其仍不會因而受影響而變得不穩定。電阻 R4 吸收所有此類的擾動，並且使 MQ3 產生的脈波 clean 且 sharp，而又因為它具有很高的電阻值，所以不致於消耗太多的電流。

You will notice in Fig 7 that I have included Diode D1 in the circuit as optional, but some Mosfets have a Sink to Source reverse biased diode already built into them, which takes away the option of not including it in the circuit. See Fig 8 below for a pictorial representation of the various "ON/OFF" states of the Hall IC and the Mosfets.

In Fig 7 above, there are 3 points on the circuit labeled A,B and C. If you connect a Battery or Capacitor across points A and B. then you are utilizing Fly-Back. If you connect a Battery or Capacitor across points B and C then you are utilizing Fly-Forward. Make sure that whichever points you connect to, you place the Battery or Capacitor in the right polarity direction as shown in the circuit. If you don't connect the polarity correctly, you will experience BIG problems!! Also you will notice the addition of Diode D2. This Diode (D2) is essential for the collection of CEMF, and also to prevent short circuits occurring when adding a secondary battery to the CEMF output. Without a diode, the secondary battery will be permanently connected across the coil if used in the Fly-Back arrangement, and will short circuit itself when the Mosfet MQ3 is turned on if it is connected in the Fly-Forward arrangement.

你也會注意到，不論是使用 Fly-Back或 Fly-Forward，流經線圈的電流始終是和主電源電流同方向。Fig 7 的電路非常穩定而且非常有用，其中 VR1 對於控制 duty cycle ("on" time) 雖然能夠提供一些彈性，不過這控制十分有限，而 duty cycle 大部分取決於triggering magnets 的寬度 ("on") 與磁鐵間的間隔 ("off")。再次的，我只對某些元件有給特定的數值，也就是電阻器。假如你是個實驗者，像是個人實驗，你為了省錢，很有可能會使用從舊電路板拆下來的舊零件。這個我已給定電阻值的電路，對於具有不同特性的大多數 Mosfet 仍能正常運作，而不會造成零件損壞。就像之前說過的，把這電路當作一個指導原則，而非不變的真理。

Also note that any of the previous simpler switching circuits on page 1 + 2 have the same capability of supplying CEMF by the addition of the diode (shown as D2 in the diagrams on this page) on the appropriate side of the coil and providing a Secondary Battery or Capacitor to charge in Flyback or Flyforward mode: Note:* Flyback recommended .