Switching power supplies (SPS) are widely used in electronic devices for their high efficiency and ability to convert input voltage to output voltage with minimal energy loss. When designing an SPS, engineers must consider the topology or circuit structure employed. This summary highlights 14 topology calculation formulas for switching power supplies:
1. Buck (Step-Down) Converter:
- Duty Cycle (D): D = Vout / Vin
- Inductor Value (L): L ≥ (Vout * (1 - D) * D * T) / (2 * ΔIL)
2. Boost (Step-Up) Converter:
- Duty Cycle (D): D = 1 - (Vin / Vout)
- Inductor Value (L): L ≥ (Vin * D * (1 - D) * T) / (2 * ΔIL)
3. Buck-Boost (Step-Up/Step-Down) Converter:
- Duty Cycle (D): D = 1 / (1 + (Vin / Vout))
- Inductor Value (L): L ≥ (Vin * Vout * T) / (2 * ΔIL * P)
4. Cuk Converter:
- Duty Cycle (D): Same as Buck-Boost
- Inductor Value (L): Same as Buck-Boost, with P replaced by Pout
5. Flyback Converter:
- Duty Cycle (D): D ≈ (Vout * N2) / (Vin * N1)
- Minimum Transformer Inductance (Lm): Lm ≥ (Vin_min * D * T) / (2 * ΔIL * N1)
6. Forward Converter:
- Duty Cycle (D): D ≈ Vout / (Vin * N2/N1)
- Minimum Transformer Inductance (Lm): Lm ≥ (Vin_min * D * T) / (2 * ΔIL * N1)
7. Push-Pull Converter:
- Duty Cycle (D): D ≈ Vout / (Vin * N2/N1)
- Minimum Transformer Inductance (Lm): Lm ≥ (Vin_min * D * T) / (4 * ΔIL * N1)
8. Half-Bridge Converter:
- Duty Cycle (D): D ≈ Vout / (Vin/2 * N2/N1)
- Minimum Transformer Inductance (Lm): Lm ≥ (Vin_min/2 * D * T) / (2 * ΔIL * N1)
9. Full-Bridge Converter:
- Duty Cycle (D): D ≈ (2 * Vout) / (Vin * N2/N1)
- Minimum Transformer Inductance (Lm): Lm ≥ (Vin_min * D * T) / (4 * ΔIL * N1)
10. Sepic Converter:
- Duty Cycle (D): Same as Buck-Boost
- Inductor Value (L1 & L2): L1 ≥ (Vin * D * (1 - D) * T) / (2 * ΔIL)
L2 ≥ (Vout * D * (1 - D) * T) / (2 * ΔIL)
11. Zeta Converter:
- Duty Cycle (D): Same as Buck-Boost
- Inductor Value (L1 & L2): Same as Sepic
12. Ćuk Converter (Modified):
- Duty Cycle (D): Same as Buck-Boost
- Inductor Value (L1 & L2): Same as Sepic
13. Quadratic Boost Converter:
- Duty Cycle (D): D = 1 - (Vin / Vout)
- Inductor Value (L): Same as Boost
14. Quadratic Buck Converter:
- Duty Cycle (D): D = Vout / Vin
- Inductor Value (L): Same as Buck
These formulas are essential for understanding the relationships between input and output voltages, duty cycles, and inductor values in various switching power supply topologies. Keeping them in mind can aid engineers in designing efficient and effective power supply systems for electronic devices.
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