Dual Active Bridge Converter Ripple Control Across Dead Time

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Solution Overview

Problem

Dual active bridge converters experience dead time-related issues in the transition region between hard-switching and soft-switching operations, leading to stagnation or self-amplification of the manipulated variable, which hinders stable regulation.

Innovation Solution

Superimposing the control variable of the dual active bridge converter with a ripple component, which can be a periodic signal, to temporarily operate outside the dead time region, ensuring a strictly monotonic characteristic of the controlled system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If dead time is introduced for switching element control, then switching operation is enabled, but stagnation or self-amplification of the manipulated variable occurs in the transition region

Engineering Contradiction:

Improveswitching element controlVSAvoidcontrol characteristic monotonicity

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

A periodic ripple signal is superimposed on the control variable to create periodic variations in the switching behavior. This periodic action ensures that the control characteristic remains strictly monotonic by preventing the system from stagnating in the dead time region, while still enabling proper switching element control through the underlying periodic switching pattern.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control variable is modified by adding a ripple component, which changes the parameter trajectory through the dead time region. This parameter change strategy ensures that the control variable does not remain stationary in the dead time region, thereby maintaining a strictly monotonic control characteristic while enabling switching operation.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If ripple component is superimposed on control variable, then strictly monotonic characteristic is achieved, but control variable fluctuates

Engineering Contradiction:

Improvecontrol characteristic monotonicityVSAvoidcontrol variable stability

Core Design Contradiction:

Stability of the object's compositionVSForce

Solution Approach 1:

The periodic ripple signal introduces controlled fluctuations that prevent stagnation. The key insight is that these fluctuations are beneficial as they ensure the control variable continuously progresses through the dead time region, maintaining monotonicity. The ripple frequency and amplitude are chosen so that the output variable remains stable despite the control variable fluctuations.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The harmful effect of control variable fluctuations is converted into a benefit by carefully selecting the ripple parameters. The fluctuations that initially seem destabilizing actually ensure monotonic progression through the dead time region, and the system design accepts these fluctuations as necessary to achieve stable overall operation with a strictly monotonic control characteristic.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12334832B2Dual active bridge converter, voltage converter arrangement and method for operating a dual active bridge converter

Publication Date: 2025.06.17 ROBERT BOSCH GMBH

AI summary

A dual active bridge converter is provided with a control variable that is superimposed with an additional ripple component to control the dual active bridge converter with a combination of the control variable and the additional ripple component.