Push-pull, half-bridge and full-bridge
Effective secondary duty, bipolar flux swing and CCM output-filter estimates.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Flux and duty convention: VO = n VP Deff; each polarity pulse = Deff/(2fs); Bpk = VP Deff/(4fs N Ae)
Assumptions
- fs is a complete positive-plus-negative transformer cycle. Rectified output ripple frequency is 2fs.
- Push-pull turns refer to one energized primary half; secondary ratio refers to the active rectifier winding. Ideal zero magnetizing offset is assumed for centered flux.
- Blocking-capacitor sizing is a conservative per-active-pulse charge bound: Q <= ton(n IO + Imag,pk/2), using the integral of the absolute centered triangular magnetizing current. It is not the half-bridge DC-link capacitor size.
- Actual blocking-capacitor charge depends on freewheel paths and commutation. Check the displayed C-Lmag resonance against control dynamics and switching operation. Leakage spikes, phase-shift commutation and capacitor midpoint balancing are omitted.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Primary stage
- full
- Minimum input
- 36 V
- Nominal input
- 48 V
- Maximum input
- 60 V
- Output voltage
- 12 V
- Output current
- 5 A
- Active secondary / active primary turns
- 0.5
- Bipolar transformer cycle frequency
- 100000 Hz
- Active primary turns
- 20
- Core effective area
- 0.0001 m²
- Allowed flux magnitude
- 0.2 T
- Output inductance
- 0.00005 H
- Output capacitance
- 0.00022 F
- Primary magnetizing inductance
- 0.002 H
- Allowed series blocking-capacitor pulse droop
- 1 V
- Chosen series blocking capacitance
- 0.00001 F
- Positive/negative volt-second imbalance
- 0.5 %
- Maximum rectified secondary duty
- 0.9
Results
- Effective secondary duty
- 0.5
- Centered bipolar peak flux
- 0.03 T
- Each primary polarity pulse / full cycle
- 0.25
- Centered magnetizing-current magnitude
- 0.03 A
- Blocking C from pulse-charge bound
- 0.0000062875 F
- Chosen blocking-C pulse-droop bound
- 0.62875 V
- Blocking-C / magnetizing-L resonance
- 1125.4 Hz
- Net flux walk per full cycle
- 0.0003 T