NAV
Can you describe how the circuit operates , please?
This help me understand how your design works.
Many thanks for you.
andy
1. PWM2 sends a pulsed voltage through Q3 into Q2 base, Q3 is already conducting because it conducts only with zero voltage at the gate.
2. The pulse train triggers the base of Q2 which allows permanent voltage into the base of Q1 and Q1 sends the pulse train into the small transformer which is a 1:10 transformer.
I will discuss that zone a little later.
3. After a set numbers of pulses which is determined by the inductance on the secondary of the transformer, the gate will deploy from PWM1.
The gate pulse must only enter the network when PWM2 is at V-. To ensure this, Q4 will only conduct when its gate voltage is zero, since its gate is driven by PWM2, it is impossible for it to conduct while PWM2 is at V+. Q4 is now in a conductive state.
4. Q4 sends forward voltage into the gate of SCR1, SCR1 is gate triggered only but can only be
turned off when PWM1 voltage is zero, so we started SCR1 with gate voltage but it only turns off when the gating period is at V-.
5. SCR1 now sends forward voltage into the gate of Q3 and this stops PWM2 voltage from driving the transformer for the duration of the gate, since Q3 can only conduct when the gate voltage is zero.
6. During the gating period, SCR1 sends forward voltage into Q6. Q6 can only be conductive when its gate voltage is zero, because Q2 has no output voltage at this time it conducts forward voltage into the Optocoupler CNY17.
7.CNY17 is being driven by a 5Khz pulse from PWM3. The transistor inside CNY17 drives the gate of Q5 at 5Khz, the emitter and collector of Q5 pick up the voltage from the secondary of the transformer and send it into the VIC at 5Khz.
The VIC we know about.
8. Q7 is not conductive during the gate period because its gate only conducts at zero voltage. When the gate period stops it conducts and sends a forward voltage from a permanent live V+ into the gate of SCR2. SCR2 Can only operate with a gate trigger and now completes the circuit back to the pick up coil on the transformer and the spark gap.
What the system does:It allows a pulse train to charge the small transformer for a time and then deploys a gating period. During the gate when PWM2 is switched off from the primary, it charges the VIC. The load impedance of the secondary on the small transformer is then intercepted before the primary can see it by the pick up coil which uses a spark gap and a ground to neutralize it. When the primary is opened again on the next forward pulse from PWM2, the load impedance of the small transformer has already been spent by the pick up coil.
You see, transformers that are driven by pulses of DC are very different from AC. On the AC transformers, the load impedance is transferred back to the primary at the cross over nodes of the AC current. On DC there are no nodes to do this just off and on. When a DC pulse ends on a transformer, the transformer becomes isolated from the power source completely because the switch is off. The coils collapse into voltage because of the change in current and the secondary begins to spend energy while the source is switched off from the transformer. The load impedance hits the source of power on the next leading edge of the next pulse. That's how they work. What I've done is to take the load impedance on the small transformer and intercepted it so that the transformer core thinks the pick up coil is the primary. The spark gap neutralizes the load impedance.
Some people might remember me saying that the energy companies rip us off by grounding their impedance to zero before it gets to our houses, well I just did the same thing in return, I grounded my load impedance to match there's. Wahahahahahahahahahahaha.