Re: [TCML] SSTC half bridge

[Steve Ward <steve.ward@xxxxxxxxx>]

You end up with a DC bias on the blocking cap proportional to
Vsupply*duty_cycle.  This is of course true when the duty cycle is exactly
50%, which means the blocker cap should have an average voltage of 1/2 the
supply voltage, which is ideal.  Deviating from this point causes the
average blocking cap voltage to drift higher or lower than Vsupply/2.  If
you end up with a duty cycle of 48:52, then it would still work just fine,
honestly. This is why we need the DC blocker caps in these types of
inverters anyway, because unless you use feedback to actively regulate to
50:50 duty cycle on average (zero volt-seconds on the transformer), then its
really quite hard to guarantee it.

I cannot think of any severe/negative consequences of non-exact 50/50 duty
cycle other than because the current is sinusoidal at resonance, then you
would be hard switching a little more than you should need to, rather than
switching at the exact zero current cross point (which is hard to achieve
anyway without special controls).

Steve

On Wed, Jun 9, 2010 at 2:27 AM, Herwig Roscher <herwig.roscher@xxxxxx>wrote:

>
> How is the system influenced if the duty cycle of the inverter was
> not exactly 1:1 ? Of course the frequency needs to be correct!
>
> Regards,
>
> Herwig
>
>
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