A deep technical dive into ripple current behavior in H-bridge circuits with inductive loads driven by PWM. The post derives closed-form formulas for peak, RMS, and harmonic content of ripple current for both edge-aligned and center-aligned PWM schemes. A key reference current I_R0 = V_DC·T/L is introduced to normalize calculations. Using Python with NumPy, SciPy, and SymPy, the author simulates and verifies the math. The central conclusion is that center-aligned PWM with common-mode duty cycle fixed at 0.5 halves ripple amplitude and doubles ripple frequency compared to edge-aligned PWM. Practical constraints like bootstrap capacitor gate drives and their effect on achievable duty cycles are also discussed.
