DAB Converter DC Magnetization Suppression via Duty Control
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Solution Overview
Problem
In DAB type DC/DC converters, DC biased magnetization in the inductance element occurs due to variations in switching elements and timing, leading to overcurrent and potential damage, with existing solutions complicating control mode switching and failing to effectively suppress main current magnetization.
Innovation Solution
A power conversion device with a controller that calculates passing currents through the inductance element, detects DC components, and adjusts the duty ratio of AC voltages to cancel out the DC components, thereby suppressing DC biased magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duty adjustment is performed separately for each bridge circuit to suppress DC biased magnetization, then DC biased magnetization can be suppressed, but control complexity increases
Solution Approach 1:
The patent combines the duty adjustment control for both bridge circuits into a unified control mechanism. The controller calculates the DC component from the passing current and simultaneously adjusts the duty ratios of both bridge circuits based on this single calculation, rather than performing separate independent adjustments for each bridge circuit.
Solution Approach 2:
The patent implements a feedback control mechanism where the controller continuously monitors the passing current through the inductance element, calculates its DC component, and uses this information to dynamically adjust the duty ratios of the bridge circuits. This closed-loop feedback ensures DC biased magnetization suppression while maintaining coordinated control.
2Measurement precision
If separate control is performed for primary side current and excitation current, then current control precision is improved, but the effect of suppressing main current magnetization is reduced
Solution Approach 1:
The patent makes the control mechanism universal by using a single control approach that simultaneously addresses both primary side current control and excitation current control. The duty adjustment based on passing current DC component affects both bridge circuits in a coordinated manner, achieving both current control precision and magnetization suppression effect through one unified mechanism.
Data Source
AI summary
A power conversion device includes a first bridge circuit, a second bridge circuit, and an inductance element connected between a first AC terminal of the first bridge circuit and a second AC terminal of the second bridge circuit. The controller calculates a passing current passing through the inductance element based on a difference between a first alternating current flowing between the first AC terminal and the inductance element and a second alternating current flowing between the second AC terminal and the inductance element, and detects a first DC component included in the passing current. The controller changes a duty in at least one of the first AC voltage and the second AC voltage to cancel the detected first DC component, the duty being a ratio of a positive potential period and a negative potential period.