Example Data Table
| Case |
Input RMS |
Input Power |
DC Bus |
Target PF |
Switching |
| Universal supply low line |
90 V |
300 W |
390 V |
0.98 |
100000 Hz |
| Single phase mains |
230 V |
520 W |
390 V |
0.98 |
65000 Hz |
| Higher power front end |
230 V |
1100 W |
400 V |
0.99 |
75000 Hz |
Formula Used
Apparent power: S = VRMS × IRMS
Measured power factor: PF = Pin / S
Reactive power: Q = √(S² - P²)
Peak rectified voltage: Vpk = √2 × VRMS
Boost duty estimate: D = 1 - Vpk / Vout
Target input current: Iin = Pin / (VRMS × PFtarget)
Inductor value: L = Vpk × D / (ΔI × fsw)
Output capacitor estimate: C = Pout / (2π × fline × Vout × ΔV)
MOSFET conduction loss: P = I² × D × RDS(on)
How to Use This Calculator
Enter the measured RMS input voltage and RMS input current.
Add real input power from a wattmeter or design estimate.
Enter the desired output power and DC bus voltage.
Set line frequency, switching frequency, and target power factor.
Choose ripple limits for inductor current and bus voltage.
Press calculate to view results above the form.
Use CSV or PDF buttons to save the same calculation.
Design Guide
Overview
A power factor boost converter shapes input current. It tries to follow the rectified mains voltage. The load sees a higher DC bus. The utility sees cleaner current. This calculator helps estimate those design values before deeper simulation.
It uses RMS line values, measured input power, output bus targets, ripple choices, and efficiency. It then reports apparent power, power factor, reactive power, bus current, duty ratio, inductor value, capacitor value, ripple current, and basic loss checks.
Why Power Factor Matters
Low power factor wastes source capacity. It also raises input current for the same useful power. A boost correction stage can reduce that problem. It forces the current waveform to track voltage. The result is lower harmonic stress and better use of wiring.
The duty ratio changes across the AC cycle. It is highest when rectified input voltage is low. It is lower near the line peak. This page gives a peak point estimate. It is useful for quick sizing. Final hardware still needs controller data, thermal testing, EMI review, and safety margins.
Design Checks
A DC bus must exceed the peak line voltage. Otherwise a boost stage cannot regulate. The tool warns when the chosen bus is too low. It also checks duty ratio, inductor ripple, capacitor ripple, and estimated semiconductor loss.
Inductor ripple is selected as a fraction of average input current. A smaller ripple improves current shape. It usually needs a larger magnetic part. A larger ripple can reduce size. It can increase stress and noise.
The output capacitor estimate uses load current, line frequency, and bus ripple. It is a first pass value. Real designs also consider hold up time, ESR, lifetime, temperature, and inrush current.
Practical Use
Use conservative inputs. Enter the lowest expected AC RMS voltage. Enter the highest expected load power. Choose an output bus above the line peak. Then review the current stresses and ripple values.
Record the assumptions beside every result. That habit makes later comparisons easier and prevents unsafe reuse of old estimates.
The CSV report is helpful for records. The PDF report is useful for quick sharing. Keep the results as estimates. Confirm the design with vendor models, control loop analysis, layout review, and lab measurements.
FAQs
What is a power factor boost converter?
It is a boost converter controlled to shape AC input current. The current follows input voltage more closely. This improves power factor and reduces wasted apparent power.
Why must the DC bus exceed line peak voltage?
A boost stage can only raise voltage. It cannot regulate below the rectified input peak. Keep the bus higher than peak line voltage plus device margin.
Is this calculator enough for final hardware design?
No. It gives early estimates. Final design needs controller selection, magnetic design, thermal checks, EMI filtering, safety review, and lab testing.
What ripple percentage should I choose?
Many early designs start near 20 to 40 percent. Lower ripple needs a larger inductor. Higher ripple can raise noise and current stress.
Why can measured power factor exceed one?
It usually means the input values are inconsistent. Real power should not exceed apparent power. Check RMS current, voltage, and wattmeter readings.
What does the capacitor result mean?
It is a first pass bus capacitance estimate. Real capacitors also need ESR, ripple current, temperature, lifetime, inrush, and hold up checks.
Why is duty ratio only a peak estimate?
In a PFC boost stage, duty changes through each line cycle. This tool reports a useful line peak point for quick sizing.
Can I download the result?
Yes. Press Download CSV for spreadsheet records. Press Download PDF for a simple report that can be saved or shared.