The latest schematics for the control electronics and power electronics can be downloaded by clicking the two links below. These schematics have been checked for obvious mistakes, and are believed to be error free. Significant improvements have been made from the original design in the following areas:
Re-configuration of the MOSFET gate drivers to reduce the dead-time at switching transitions. The old design had a large 5% dead-time at switching instants to allow one MOSFET to turn off before the other is turned on. This dead-time was found to be excessive, and caused the body diodes of the MOSFETs to conduct heavily due to the free-wheeling current.
Isolation of the MOSFET body diodes, using series a Schottky diode and parallel fast recovery diodes. This eliminates problems due to the slow reverse recovery characteristics of the body diode. This modification combined with the one explained above, dramatically reduces MOSFET mortality rates !
Dynamic tuning. The carrier signal generated by the TL494 is "Frequency modulated" by the HV supply voltage. The frequency is actually swept down by a few percent as the voltage increases in an attempt to track the resonator frequency as the sparks grow. This is quite rough, as is does not take into account that detuning only happens above breakout, etc. However it has been found to be very effective, most likely because the loaded resonator Q is low, and the tuning range is actually quite broad during sparking conditions ?
-----引自图原作者的HomePage
确实死区时间是为了防止共态,也确实是防止体二极管损坏,所以作者后来对体二极管进行了屏蔽,即第二条。但是我在实验过程中确实发现死区,确切说是是占空比对SSTC的影响巨大:当我的3525H桥输出占空比调到最大时,反倒是没有电弧输出,经示波器观察此时有大约10%的死区,画出波形图,可以理解此时输出信号的相位根本无法“卡在”次级谐振状态上!反倒是当我把占空比拧到为on:deadtime=1:1时出了点小弧,原因很显然,不再分析~
补偿弧容是原图作者后来加的,我强调着一点是为了说明图1的问题,并没有否定后来这个图加的这个反馈~其实我一直想不明白这个反馈环路为什么那么有效,原作者也没给出详细解释~
关于初级线圈,我确实忘了说明要加大耦合度,因为对于SSTC,耦合度越高,能量传递效率越大,并不需要像DRSSTC那样考虑初级能量对次级自由振荡的影响~当然加大初级电流也是为了这个目的!
在此感谢black的指导!