Transformer-Isolated Gate Drive With Duty-Independent Voltage

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Solution Overview

Problem

Existing power switching devices are inflexible and require complex configurations, with driving voltage levels dependent on the duty cycle of the input voltage, necessitating additional power from the controller to operate effectively.

Innovation Solution

A power switching device incorporating a buffer circuit, filter circuit, restoration circuit, and conditioning circuit, which operates as a plug-and-play module, isolating the primary and secondary sides using a transformer, allowing operation with standard controllers and providing independent driving voltage levels regardless of duty cycle, and featuring protection circuits for safe operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the power switching device uses a transformer to isolate primary and secondary sides, then the controller's power supply is not affected, but the device complexity increases

Engineering Contradiction:
Improvecontroller power supply stabilityVSAvoidcircuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A transformer is introduced as an intermediary component to isolate the primary side (controller) from the secondary side (power switching device). The transformer transfers power and control signals galvanically, preventing power supply interference while maintaining controlled communication. This resolves the contradiction by providing reliable isolation without requiring direct electrical connection.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The power switching device is segmented into distinct functional modules: a primary side containing the controller, and a secondary side containing the power switch and associated circuits. The transformer acts as the interface between these segments. This modular segmentation allows independent optimization of each side while maintaining system reliability.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If the driving voltage level depends on the duty cycle of the input voltage, then the circuit can be simpler, but the adaptability to different applications is reduced

Engineering Contradiction:
Improveapplication flexibilityVSAvoidvoltage regulation circuit
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention decouples the driving voltage level from the duty cycle parameter by introducing a dedicated voltage generation circuit on the secondary side. This circuit generates a fixed voltage level that remains constant regardless of duty cycle variations. The parameter change principle is applied by transforming the variable duty cycle into a stable voltage reference, enabling adaptability across different applications without requiring voltage regulation complexity.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the controller provides the required power to operate the circuit, then the ease of operation is improved, but the loss of energy increases

Engineering Contradiction:
Improvecontroller operationVSAvoidcontroller power consumption
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The transformer serves as an energy transfer intermediary that enables the power switching device to draw its operating power from the power stage rather than from the controller. The transformer couples the power stage to the secondary side circuits, allowing efficient power transfer without requiring the controller to supply significant current. This reduces controller power consumption while maintaining ease of operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The power switching device on the secondary side is designed to be self-powered through the transformer coupling. The circuit generates its own operating voltages and currents from the power stage input, making it independent of the controller's power supply capabilities. This self-service approach minimizes controller energy expenditure while maintaining full operational functionality.

Inventive Principle:
Principle #25Self-service

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 flexible and easy operation of power switching devices with standard controllers, reduces driving losses, and provides high switching frequency without affecting the controller's power supply, while offering protection features like overcurrent and temperature protection.

Implementation Method 1

Dependent on the transformation ratio the alternating primary side voltage is transformed into an alternating secondary side voltage by the transformer. Furthermore, due to the transformer the secondary side is isolated from the primary side.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The filter circuit is designed to block a direct component of the buffer output voltage and to provide an alternating primary side voltage.

Methodology Applied
Scientific EffectCapacitive blocking: Capacitance

Data Source

PatentEP3476046B1Power switching device and method to operate said power switching device
Publication Date: 2019.12.18 WURTH ELEKTRONIK EISOS
  • EP3476046B1 patent drawingFigure 1
  • EP3476046B1 patent drawingFigure 2~3
  • EP3476046B1 patent drawingFigure 4~5

AI summary

A power switching device (1) comprises a buffer circuit (3), a filter circuit (4), a transformer (5), a restoration circuit (9), a conditioning circuit (10) and a power switch (13). The buffer circuit (3) provides a unipolar buffer output voltage (Vb) dependent on an input voltage (Vin) and a control voltage (VG). The filter circuit (4) blocks a direct component of the buffer output voltage (Vb) which is added on the secondary side of the transformer (5) by the restoration circuit (9). The power switch (16) is controlled by a unipolar conditioning voltage (VD) provided by the restoration circuit (9) to the conditioning circuit (10). The power switching device (1) acts as a plug and play module and can be used and operated in a flexible and easy manner.