Coupled-Inductor Phase Control for Low-Ripple Power Converters

Solution Overview

Problem

Multi-phase power converters using coupled inductors face efficiency losses due to current ripple in the common magnetic core and unequal average current delivery from phase circuits, leading to reduced efficiency and increased energy loss over time.

Innovation Solution

The power converter circuit employs a control circuit to initiate active periods for phase circuits, cycling between on-time and off-time periods based on current comparisons and threshold values, maintaining an initial phase difference to reinforce phase relationship and minimize current ripple, thereby equalizing average currents and reducing energy loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If coupled inductors are used in multi-phase power converters, then power conversion capability is improved, but current ripple in the common magnetic core causes efficiency losses

Engineering Contradiction:

Improvepower conversion capabilityVSAvoidefficiency losses

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent implements periodic phase shifting between multi-phase power converter circuits, where each phase is periodically delayed relative to the previous phase. This periodic action ensures that current ripple from one phase does not accumulate in the common magnetic core, thereby reducing efficiency losses while maintaining power conversion capability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary phase shifting to the clock signals before they reach the phase circuits. By pre-delivering delayed clock signals to each successive phase circuit, the system establishes the desired phase relationships in advance, preventing current ripple accumulation before it occurs in the coupled inductors.

Inventive Principle:

Principle #10Preliminary action

2Power

If phase circuits operate simultaneously, then power delivery capability is improved, but unequal average current delivery reduces efficiency

Engineering Contradiction:

Improvepower delivery capabilityVSAvoidefficiency

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent implements periodic phase shifting between multi-phase power converter circuits, where each phase is periodically delayed relative to the previous phase. This periodic action ensures that current ripple from one phase does not accumulate in the common magnetic core, thereby reducing efficiency losses while maintaining power conversion capability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary phase shifting to the clock signals before they reach the phase circuits. By pre-delivering delayed clock signals to each successive phase circuit, the system establishes the desired phase relationships in advance, preventing current ripple accumulation before it occurs in the coupled inductors.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If phase shift is not controlled, then circuit complexity is reduced, but phase relationship drift causes current ripple

Engineering Contradiction:

Improvecircuit complexityVSAvoidcurrent ripple

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent introduces delay elements as intermediary components between the clock signal source and each phase circuit. These delay elements act as mediators that precisely control the phase shift between circuits without requiring complex control logic, thereby maintaining simple circuit architecture while preventing current ripple through controlled phase relationships.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies preliminary phase shifting to the clock signals before they reach the phase circuits. By pre-delivering delayed clock signals to each successive phase circuit, the system establishes the desired phase relationships in advance, preventing current ripple accumulation before it occurs in the coupled inductors.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the efficiency of the power converter by maintaining a consistent phase relationship between phase circuits, reducing energy loss and ensuring equal current delivery, thus improving overall efficiency and reducing energy waste.

Implementation Method 1

a first coil of a pair of coupled inductors... a second coil of the pair of coupled inductors

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentUS11837960B2Phase shift error mitigation for power converters with coupled inductors

Publication Date: 2023.12.05 APPLE INC

AI summary

A power converter circuit that includes multiple phase circuits may employ coupled inductors to generate a particular voltage level on a regulated power supply node. In response to an initiation of an active time period, the phase circuits cycle, out of phase with each other, between on-times and off-times. To maintain the phase relationship between the operation of the phase circuits, each phase circuit generates a ramp current that is compared to the current flowing in its corresponding inductor and then halts an off-time based on a result of the comparison.