BLDC Inverter Loss Calculator
This tool models the thermal performance of a 3-Phase Inverter Bridge. It accurately calculates Conduction, Switching, and Diode Recovery losses for MOSFETs or IGBTs.
Toggle between Trapezoidal (Square Wave/6-Step) and Sinusoidal (PWM/FOC) modulation to visualize how different control strategies impact thermal efficiency.
System Parameters
DriveDevice Specifications
MOSFETLoss Analysis
LiveModulation Topology Comparison
Understanding the difference between 6-step trapezoidal and sinusoidal modulation is critical for thermal management.
| Feature | Trapezoidal (6-Step) | Sinusoidal (PWM/FOC) |
|---|---|---|
| Conduction | 2 Phases Active (120°) | 3 Phases Active (180°) |
| Switching Loss | Lower (Only 2 legs switch) | Higher (All 3 legs switch) |
| Torque Ripple | High (Commutation bumps) | Low (Smooth rotation) |
| Best Application | High Speed / Simple Fans | Precision Servo / EV |
Included Loss Models
Conduction (Pcond)
Trap: Ipk² × RDS × (1/3)
Sine: (Ipk / √2)² × RDS × 0.5
Uses Temperature-adjusted RDS(on).Switching (Psw)
0.5 × Vbus × Ipk × (tr + tf) × fsw
Averaged over the active modulation period.Dead Time (Pdt)
VSD × Iavg × tdead × fsw
Body diode conduction during the dead time gap.Reverse Recovery (Prr)
Qrr × Vbus × fsw
Energy lost when body diode turns off.How to Use
Estimate drive thermal performance.
Select Mode
Choose Trapezoidal for 6-step BLDC (2 phases active) or Sinusoidal for FOC PMSM (3 phases active).
Define System
Enter Bus Voltage, Peak Current, and Frequency. Don’t forget Dead Time if you are pushing high frequencies.
Check Heatsink
The Total Inverter Loss dictates your heatsink size. Keep the Junction Temp below 125°C for reliability.