DC-DC Converter Freewheeling Path for Low-Noise High-Voltage Switching
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Solution Overview
Problem
Existing DC-DC converters face challenges in handling high voltages and powers while maintaining low noise levels due to difficulties in simultaneous transistor switch-off and coil current buildup, which can cause potential shifts and damaging interfering currents.
Innovation Solution
A DC-DC converter design with a switchable first and second circuit path, coupled by an inductive element, and a parallel freewheeling path to absorb coil current during switching, allowing for defined freewheeling intervals and potential shift detection to prevent damage and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If semiconductor isolation with transistors is used to enable high voltage and power operation, then operating voltage and power range are improved, but simultaneous switch-off of transistors becomes difficult to ensure and coil current may cause damaging interfering currents
Solution Approach 1:
A freewheeling path is introduced as an intermediary circuit element connected in parallel with the inductive element. This freewheeling path provides a dedicated route for coil current during switching transitions, preventing the current from causing damaging interfering currents when transistors switch states. The freewheeling path acts as a buffer that mediates between the inductive element and the switching transistors, enabling reliable high-power operation.
Solution Approach 2:
The control device activates the freewheeling path in advance during the time lag between switching intervals. By preparing the freewheeling path before the actual switching event, the system ensures that coil current has a predetermined safe path before transistor switch-off occurs, preventing potential damage from uncontrolled current flow.
2Productivity
If transistor switching is used for DC-DC conversion, then converter functionality is improved, but electromagnetic interference and noise level increase due to abrupt potential shifts
Solution Approach 1:
The freewheeling path serves as an intermediary that smooths out abrupt potential shifts during transistor switching. By providing a controlled current path during transitions, it prevents the generation of high-frequency interfering currents that would otherwise be produced by sudden changes in coil current, thereby reducing electromagnetic interference while maintaining converter functionality.
3Duration of action of moving object
If diagonal connection of DC networks occurs during switching, then circuit operation continues, but potential separation and isolation are destroyed causing damaging interfering currents
Solution Approach 1:
The control device prepares the freewheeling path in advance during the time lag before switching events. This preliminary activation ensures that when diagonal connection attempts to occur during transistor switching, the coil current already has a safe predetermined path through the freewheeling path, preventing the destruction of potential separation and isolation between DC networks.
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 operation with high voltages and powers while minimizing electromagnetic interference by ensuring safe switching and isolating DC networks, even in fault conditions.
Implementation Method 1
a second circuit path coupled to the first circuit path by way of an inductive element
Implementation Method 2
provides a possibility of dissipating the coil current in the event of a fault, namely via the ohmic resistance of the freewheeling path
Data Source
AI summary
A DC-DC converter includes a converter circuit including a switchable first circuit path that is in a conductive state in a first time interval and that has at least a first and a second switchable element interconnected in series, and including a second circuit path that is coupled to the first circuit path by way of an inductive element and that is in a conductive state in second time interval disjunct from the first time interval, wherein there is a time lag between the first time interval and the second time interval. A control device is configured to switch the first circuit path. A switchable freewheeling path is coupled in parallel with the inductive element, wherein the control device is configured to switch the switchable freewheeling path temporarily to a conductive state in a freewheeling interval during the time lag.