Boost calculations

Boost calculations

1. Minimum needed inductance
2. Check for continuous or discontinuous mode
3. On- and off-time
4. Voltages and currents on components
5. General calculations

1. Minimum needed inductance

The calculation is done with the minimum input voltage to achieve the desired current ripple in continuous conduction mode.

Peak-to-peak inductor current ripple

Minimum needed inductance at minimum input voltage

2. Check for continuous or discontinuous mode

It has to be checked if the boost converter is working in continuous or discontinuous mode to use the proper formulas.

Maximum input current

Current ripple with choosen indcutance

Check for continuous or discontinuous mode

3. On- and off-time

    Depending on the mode (continuous or discontinuous) different formulas are needed.

    t_on    - FET is in on-state (continuous and discontinuous mode)
               - Inductor current is rising

    t_off       - FET is in off-state (continuous and discontinuous mode)
             - Inductor current is falling

    t_zero     - time slot when inductor current is zero
             - occurs only in discontinuous conduction mode

    Duty cycle

On-time is continuous conduction mode

Off-time in continuous condcution mode

On-time is discontinuous conduction mode

Off-time in discontinuous condcution mode

Time slot when inductor current is zero (only in discontinuous condcution mode)

4. Voltages and currents on components

Depending on the mode (continuous or discontinuous) different formulas are needed.

Minimum current in continuous conduction mode (FET, diode, inductor)