Asymmetric Inductor Phase-Shifting for DC-DC Converter Ripple
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Solution Overview
Problem
Existing multi-phase DC-DC switching converters with asymmetric inductors face inefficiencies due to suboptimal phase-shifting configurations, leading to increased output voltage ripple and reduced efficiency, as conventional methods like 360 deg/number-of-phase do not minimize current ripple amplitudes effectively.
Innovation Solution
An n-phase buck converter with asymmetric inductors is configured to achieve optimal phase-shifting by ensuring the sum of inductor current vectors equals zero, using a clock generator or synchronous logic circuit to generate phase-shifted PWM pulses based on inductance values, minimizing output voltage ripple and total inductor current ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional phase-shifting configuration (360 deg/number-of-phase) is used, then the converter structure is simple, but the output voltage ripple is increased
Solution Approach 1:
The patent changes the phase-shifting angle parameter from the conventional uniform distribution (360/N) to asymmetric distribution based on inductor current ripple amplitudes. The phase shift between adjacent phases is set to π - 2θ where θ = arcsin((L2/L1) * sin(α)), creating optimized asymmetric phase shifts that minimize output voltage ripple while maintaining converter functionality.
Solution Approach 2:
The patent applies asymmetry by using different phase-shifting angles for different phase pairs instead of uniform distribution. The first phase shift between phase 1 and phase 2 differs from the second phase shift between phase 2 and phase 3, creating an asymmetric phase configuration that optimally cancels current ripple components based on the specific inductor values.
2Loss of energy
If asymmetric inductors with different values are used, then the efficiency over wide load range is improved, but the current ripple amplitudes become different requiring optimized phase-shifting
Solution Approach 1:
The patent optimizes the phase-shifting angle parameters based on the asymmetric inductor values to minimize output voltage ripple. By calculating θ = arcsin((L2/L1) * sin(α)) and setting phase shifts to π - 2θ, the system achieves optimal ripple cancellation that adapts to the specific asymmetric inductor configuration, maintaining high efficiency across wide load ranges.
Solution Approach 2:
The patent uses the inductor current ripple amplitudes as feedback to determine the optimal phase-shifting configuration. The phase shifts are calculated based on the ratio of inductor values and the duty cycle, creating a feedback mechanism where the asymmetric current characteristics directly inform the phase-shift optimization strategy.
3Object-generated harmful factors
If optimized asymmetric phase-shifting is implemented, then the output voltage ripple is minimized, but the control circuit complexity increases
Solution Approach 1:
The patent implements optimized asymmetric phase-shifting by calculating specific angle parameters (θ = arcsin((L2/L1) * sin(α)), phase shift = π - 2θ) that minimize output voltage ripple. This parameter optimization achieves superior ripple reduction compared to conventional uniform phase distribution.
Solution Approach 2:
The patent makes the phase-shifting configuration dynamic by adjusting the phase shifts based on the duty cycle α and inductor value ratio. As the duty cycle changes with load conditions, the optimized phase shifts adapt accordingly, maintaining minimal output voltage ripple across varying operating conditions rather than using fixed symmetric angles.
Data Source
AI summary
A system is disclosed which provides the minimization of peak-to-peak output voltage ripple in multi-phase DC-DC switching converters, with two or more different value inductors (asymmetric inductors), by the optimization of phase-shifting determined by the inductance on each phase. An object of the disclosure is to ensure both the AC accuracy of the output voltage and the efficiency of the DC-DC switching converter is increased. The output voltage ripple improvement is shown to be dependent on the duty-cycle. Another object of the disclosure is to minimize the total inductor current ripple and improving the efficiency of the DC-DC switching converter by reducing the capacitor loss. Still another object of the disclosure is to minimize the output voltage ripple in the multi-phase DC-DC switching converter by ensuring the sum of the inductor current vectors is equal to zero.