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Boost Converters (Non-Isolated)


Used for:

Stepping a voltage up in value with high efficiency


Pros:



Cons:


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Basics:

SW1 and SW2 are alternately on and off at high frequency

SW1 and SW2 are never both on or both off together

Vout = Vin/(1- D) where D is the switching duty cycle (0 -1)

Input ripple current is low, set by inductor L

Output ripple current is high and is sunk into C2

SW2 can be a diode - the action of SW1 turning off automatically forward biases the diode causing it to conduct. Action of SW1 turning on reverse biases the diode causing it to block current


SW2

SW1

Boost literature references

CONTROL LOOP PARAMETERS for fixed frequency PWM control

Vramp = amplitude of sawtooth ramp    

Ri = Rsense x Current gain eg. Rsense x 100 for 100:1 sense transformer    

Optimum slope compensation assumed in each case    

D = Duty cycle    

f = operating frequency