boylesg
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How critical is the capacitor value here? Is it sufficient to just select a capacitor/inductor combination with an appropriate period and with a capacitor value as large as possible, i.e. without doing this
**broken link removed** 3 - Non-Dissipative Snubber Circuit
Both of the preceding snubber circuits can dissipate large amounts of power through the corresponding resistors. Not only does this cause inefficiencies, but it creates heat transfer problems, and increases component sizes.
The following non-dissipative snubber in figure 2 is overcomes these problems by storing the leakage voltage spike energy into a capacitor when the transistor shuts off. When the transistor turns on again, energy is poured into a parallel inductor, which resonates with the storage capacitor.
**broken link removed**
Figure 2 - Non-dissipative snubber circuit. Energy is stored into C1 when the transistor turns off. When Q1 turns on, L2 and C1 form a resonant circuit, and energy that swashes above VP+VD1 is transferred back to the load L1.
The resonant circuit formed by L2 and C1 when Q1 is turned on rings at a frequency of:
F=1/(2*PI*sqrt(L2*C1))
The voltage across L2 will ring negative for the first ring cycle, and then will ring positive for the second. When the voltage across L2 is positive and exceeds VP+ 2*VD all of the leakage energy is transferred back into the supply.
The design steps for selecting component values are simple. First select a capacitor which slows the rise time sufficiently, to lower the overshoot. Selection of the capacitor is by trial and error, since the magnitude of the leakage inductance isn't usually known before hand. After selecting C1, select an inductor such that the two cycle ring period is less than the minimum on time of the transistor - Ton.
- - - Updated - - -
I don't really get this. I set this snubber up in the javascript applet thing to visualise how this snubber works. And the diodes prevent any part of it 'ringing negative'
The kickback is forced clockwise through the flyback transformer(represented by an inductor) / capacitor circuit.
Then, when it would normally flow anti-clockwise through a regular RC snubber network, it is forced by the diodes to flow clockwise through the snubber inductor / flyback transformer circuit.
since I don't have an oscilloscope.
**broken link removed** 3 - Non-Dissipative Snubber Circuit
Both of the preceding snubber circuits can dissipate large amounts of power through the corresponding resistors. Not only does this cause inefficiencies, but it creates heat transfer problems, and increases component sizes.
The following non-dissipative snubber in figure 2 is overcomes these problems by storing the leakage voltage spike energy into a capacitor when the transistor shuts off. When the transistor turns on again, energy is poured into a parallel inductor, which resonates with the storage capacitor.
**broken link removed**
Figure 2 - Non-dissipative snubber circuit. Energy is stored into C1 when the transistor turns off. When Q1 turns on, L2 and C1 form a resonant circuit, and energy that swashes above VP+VD1 is transferred back to the load L1.
The resonant circuit formed by L2 and C1 when Q1 is turned on rings at a frequency of:
F=1/(2*PI*sqrt(L2*C1))
The voltage across L2 will ring negative for the first ring cycle, and then will ring positive for the second. When the voltage across L2 is positive and exceeds VP+ 2*VD all of the leakage energy is transferred back into the supply.
The design steps for selecting component values are simple. First select a capacitor which slows the rise time sufficiently, to lower the overshoot. Selection of the capacitor is by trial and error, since the magnitude of the leakage inductance isn't usually known before hand. After selecting C1, select an inductor such that the two cycle ring period is less than the minimum on time of the transistor - Ton.
L1= Ton(min)2/(4*PI2C1)
- - - Updated - - -
I don't really get this. I set this snubber up in the javascript applet thing to visualise how this snubber works. And the diodes prevent any part of it 'ringing negative'
The kickback is forced clockwise through the flyback transformer(represented by an inductor) / capacitor circuit.
Then, when it would normally flow anti-clockwise through a regular RC snubber network, it is forced by the diodes to flow clockwise through the snubber inductor / flyback transformer circuit.
