Flyback Converter Negative Bias Generation for High-Side Switches
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-voltage inverters face challenges in providing a negative bias voltage for high-side switches, leading to undesired activation due to parasitic capacities and steep voltage changes, which increases construction size, weight, and production costs, especially in vehicle applications.
Innovation Solution
A configuration that generates a negative base voltage using an enhanced flyback converter with an additional winding, allowing for the generation of multiple bias voltages for high-side switches, and optionally using a bootstrap switch to provide a negative voltage independent of floating potential, reducing the need for additional transformer windings and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional transformer windings and insulation are added to generate negative bias voltage, then the reliability of high-side switch protection is improved, but the device complexity and construction size increase
Solution Approach 1:
The patent merges the negative bias voltage generation function with the existing flyback converter by utilizing its primary winding and semiconductor switch. The same primary winding that generates positive bias voltages is repurposed to generate negative bias voltage through appropriate circuit configuration, eliminating the need for separate transformer windings and reducing overall device complexity while maintaining protection reliability.
Solution Approach 2:
The flyback converter's primary winding is designed to serve multiple functions: generating positive bias voltages for driver circuits and simultaneously generating negative bias voltage for high-side switch protection. This multi-functionality approach eliminates redundant components and simplifies the transformer structure while ensuring reliable protection against parasitic activation.
2Reliability
If multiple separate negative voltage supplies are provided for each high-side switch, then the protection against parasitic activation is improved, but the weight and construction size increase
Solution Approach 1:
The patent combines the generation of negative bias voltages for all high-side switches into a single unified circuit based on the flyback converter's primary winding. Instead of providing separate negative voltage supplies for each high-side switch, the system generates a common negative base voltage that can be distributed to multiple switches, thereby reducing the overall weight and construction size while maintaining adequate protection against parasitic activation.
3Ease of operation
If a separate voltage supply is added for driver circuit operation, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The patent combines the driver circuit power supply function with the high-side switch protection function by using the same flyback converter primary winding to generate both positive bias voltages for driver operation and negative bias voltage for protection. This integrated approach provides all necessary voltages through a single configuration, improving ease of operation while avoiding the increased complexity that would result from separate voltage supply systems.
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
This solution prevents undesired activation of high-side switches, reduces the complexity and size of the flyback transformer, and lowers production costs by simplifying the circuit and eliminating unnecessary components, enhancing the robustness of the design, particularly in vibrating environments like vehicles.
Implementation Method 1
a primary winding of a transformer of a flyback converter that is connected to a semiconductor switch
Data Source
AI summary
A configuration and a method for generating a negative voltage for a high-side switch in an inverter by providing at least one negative bias voltage for an inverter, wherein a simple and safe provision of the negative voltage becomes possible, and the switching costs as well as the costs and expenses for the production of such an inverter are reduced. A secondary winding generating a negative base voltage is arranged on a flyback transformer, wherein a first terminal of the secondary winding is connected to the HV+ potential and a second terminal of the secondary winding is connected via a rectifier diode to the first terminal for outputting the negative base voltage, wherein a bootstrap diode is arranged between the first terminal and a second terminal for outputting a negative base voltage (NEG BIAS A), and wherein a bootstrap capacitor is arranged between the first terminal and the second terminal.