Bridge Topology Switching Method Reduces Inductor Current Ripple

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Solution Overview

Problem

Conventional bridge topology power converters, particularly in buck-boost mode, suffer from inefficiencies due to switching losses and rippled inductor currents, which are exacerbated by the simultaneous operation of multiple switches, leading to high average inductor currents and energy losses.

Innovation Solution

A buck-boost switching regulator with control circuitry that adjusts phase relationships between boost and buck switches to reduce ripple current, utilizing a digital signal processor to generate control signals that synchronize switch on-times and off-times, thereby minimizing inductor current variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If switches are operated simultaneously in bridge mode, then power conversion is achieved, but ripple current increases and efficiency decreases

Engineering Contradiction:

Improvepower conversion capabilityVSAvoidripple current losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies periodic action by implementing phase-shifted PWM control where buck switches and boost switches are operated in alternating phases rather than simultaneously. The control circuitry generates PWM signals with specific phase relationships, causing switches to operate in a sequential periodic manner that reduces overlapping current transitions and minimizes ripple current in the inductor.

Inventive Principle:

Principle #19Periodic action

2Adaptability or versatility

If multiple switches are closed simultaneously, then bridge mode operation is achieved, but switching losses increase

Engineering Contradiction:

Improvebridge mode operationVSAvoidswitching losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the switch operation timing adjustable and adaptive. The control circuitry dynamically adjusts the phase relationships and timing of PWM signals based on operating conditions, allowing the system to optimize switch transition timing to minimize simultaneous switching events and reduce switching losses while maintaining bridge mode functionality.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If inductor current varies between switch on/off periods, then switching operation is achieved, but current ripple increases

Engineering Contradiction:

Improveswitching operationVSAvoidinductor current stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent applies feedback by using the control circuitry to monitor and adjust switch timing based on current operating conditions. The system incorporates feedback mechanisms that detect current ripple and adjust the phase relationships between buck and boost switch PWM signals to minimize current variations, thereby stabilizing the inductor current while maintaining effective switching operation.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8749215B2Switching method to reduce ripple current in a switched-mode power converter employing a bridge topology

Publication Date: 2014.06.10 TEXAS INSTRUMENTS INC

AI summary

Traditionally, buck-boost switching regulators with bridge topologies have been avoided due to their inability to seamlessly transition between buck mode and boost mode. Here, however, a buck-boost switching regulator with a bridge topology has been provided, which has an improved controller. Namely, a processor (such as a digital signals processor or DSP) provides digital control for the bridge that reduces ripple current or variations in the inductor current by adjusting phase relationships between corresponding buck and boost switches in a bridge or buck-boost mode.