動作原理
A dual active bridge (DAB) converter connects two full bridges through a high-frequency transformer and a series inductance. Power flows from the leading bridge to the lagging bridge, and its amount is set by the phase shift between the two square-wave voltages. Because both bridges are active, power can flow in either direction, which makes DAB a common choice for battery chargers, energy storage and solid-state transformers.
Single phase shift (SPS) modulation uses one phase shift d between the bridges. It is simple but circulates large reactive currents when the voltage conversion ratio M is far from 1. Dual phase shift (DPS) adds an inner phase shift inside each bridge, and triple phase shift (TPS) uses independent inner shifts, both of which reduce current stress and widen the ZVS range.
For SPS, this calculator designs the series inductance from your maximum power and a chosen maximum phase shift, then solves for the phase shift at the selected operating point. It also checks the necessary and sufficient zero-voltage switching conditions, including the effect of the switches' parasitic capacitance.
DPS and TPS results are normalized to a base power P_N so that different designs can be compared directly. Conventions for n and d differ between papers, so check the definitions above before comparing with other references.
計算式
- Voltage conversion ratio
- M = V2 / (n · V1)
- SPS transferred power (as used here)
- P = d · (1 − d) · V1 · V2 / (n · f_s · L_k)
- Series inductance (design 1)
- L_k = (1 − d_max) · d_max · V1 · V2 / (n · f_s · P_max)
- Base power for DPS/TPS normalization
- P_N = n · V1 · V2 / (8 · f_s · L)
計算例
With V1 = 48 V, V2 = 400 V, 1 kW at 100 kHz and d_max = 0.35, leaving n empty sets n = V2 / V1 ≈ 8.33 so M = 1 at full power. The design gives L_k ≈ 5.2 µH and an inductor peak current of about 32 A.
よくある質問
When should I use DPS or TPS instead of SPS?
When the voltage conversion ratio moves far from 1, for example with a wide battery voltage range, SPS loses ZVS at light load and its RMS current rises. DPS and TPS reduce both problems at the cost of more complex control.
What does the phase shift d mean?
d is the phase shift between the two bridge voltages as a fraction of half a switching period. Normal operation uses 0 < d ≤ 0.5; maximum power transfer happens at d = 0.5.
Why does the ZVS check include parasitic capacitance?
The inductor current at the switching instant must be large enough to charge and discharge the switch output capacitances before the next switch turns on. Larger capacitance needs more current.
計算結果は工学的な推定値です。データシート、シミュレーション、実測で設計を確認してください。