Table of Contents
Parallel Inductors
When inductors are connected in parallel (assuming no mutual coupling), the total inductance is less than the smallest individual inductor. This is analogous to parallel resistors. The parallel combination allows more magnetic flux paths, effectively reducing the opposition to current changes.
Parallel inductor configurations are used in power electronics, RF filters, and impedance matching networks. In practice, mutual inductance between parallel inductors can increase or decrease the total inductance depending on the coupling direction and coefficient.
Formula
Series vs Parallel Inductors
| Property | Series | Parallel |
|---|---|---|
| Total L | Sum of all L | Less than smallest L |
| Current | Same through all | Divides among inductors |
| Voltage | Divides across each | Same across all |
Frequently Asked Questions
Does mutual inductance matter?
Yes. When inductors are physically close, their magnetic fields interact. This mutual inductance (M) modifies the formula. For two parallel inductors: L = (L1L2 - M²)/(L1 + L2 - 2M) for aiding coupling, or (L1L2 - M²)/(L1 + L2 + 2M) for opposing coupling.
Why use parallel inductors?
To reduce inductance below available values, to increase current capacity (each inductor carries only a fraction of total current), and to reduce DC resistance. In high-current power supplies, parallel inductors share the load and reduce thermal stress.