DC Component Suppression in Transformer Voltage Converters
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Solution Overview
Problem
Full-bridge voltage converters face limitations in controlling asymmetrical currents, leading to transformer saturation and reduced regulating range due to the need for a reset phase that prevents current sense transformer saturation, which is not suitable for high-power applications.
Innovation Solution
A voltage converter with a control device that detects asymmetry in the current profile of the primary coil using a measuring device that cannot measure direct current, allowing for adjustments in PWM signals to balance the asymmetry and prevent saturation, using techniques such as peak current control and galvanically decoupled measurement via a measuring transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reset phase is introduced to prevent current sense transformer saturation, then the current sense transformer can measure current accurately, but the control or regulating range for PWM signals is limited
Solution Approach 1:
The patent extracts the DC component detection function from the current sense transformer by using a measuring device that measures voltage across an impedance element. This separation allows the current sense transformer to focus on AC current measurement while the DC component is detected through voltage measurement, eliminating the need for reset phases and expanding PWM control range.
Solution Approach 2:
The patent introduces an impedance element as an intermediary between the primary coil and the measuring device. This impedance element converts the difficult-to-measure DC current component into a measurable voltage signal, enabling DC component detection without requiring the current sense transformer to handle DC measurements, thus avoiding saturation issues.
2Measurement precision
If a current sense transformer is used to measure current in the supply line, then current measurement is possible, but the transformer goes into saturation and can no longer be used for measuring
Solution Approach 1:
The patent extracts the DC component measurement function from the current sense transformer by measuring voltage across a separate impedance element. This separation prevents the current sense transformer from handling DC current, eliminating saturation and ensuring continuous reliable operation for AC current measurement.
Solution Approach 2:
The patent creates a voltage copy of the current signal by measuring the voltage across the impedance element. This voltage copy contains information about the DC component and can be used for control purposes without requiring the original current sense transformer to measure DC current directly.
3Adaptability or versatility
If asymmetrical currents are supplied to the converter transformer, then different supply intervals can be set, but the transformer may go into saturation causing damage
Solution Approach 1:
The patent implements feedback by continuously detecting the DC component of the current supplied to the primary coil and using this information to adjust the PWM signals. The control device detects asymmetry in the current profile and balances it by adjusting PWM duty cycles, preventing transformer saturation while maintaining flexible supply intervals.
Solution Approach 2:
The patent performs preliminary detection of the DC component and asymmetry in the current profile before saturation can occur. By detecting asymmetry early and adjusting PWM signals proactively, the system prevents transformer saturation rather than reacting after damage has occurred.
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
Enables the detection and balancing of asymmetrical currents within the primary coil, preventing transformer saturation and maintaining the full regulating range for voltage conversion, even in high-power applications.
Implementation Method 1
a measuring device which is not able to measure direct current... galvanically decoupled measurement via a measuring transformer
Implementation Method 2
full-bridge device which is designed to receive a first DC voltage from a voltage source and to route it to a primary coil
Data Source
AI summary
The present invention relates to a voltage converter comprising a primary side which has a full bridge device which is configured for the purpose of receiving a first DC voltage from a voltage source at a first amplitude and to transmit same to a primary coil arranged in the primary side, comprising a control unit which is designed for the purpose of controlling the full bridge device using PWM signals having phases shifted counter to one another, wherein the control unit is configured to detect an asymmetry in the current supplied to the primary coil based on a current profile in the primary coil, wherein the control unit is designed to compensate for a detected asymmetry by adjusting the PWM signals. The present invention further relates to a corresponding method.