SiC Transistor Control Device Asymmetric Drive Voltage
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Solution Overview
Problem
Current driver circuits are unsuitable for silicon carbide transistors as they often use symmetrical driving voltages, which can damage the transistors.
Innovation Solution
A control device comprising a chopper assembly, transformer, rectifying circuit, flip-flop, switching assembly, and shift circuit to generate a control voltage with peak-to-peak amplitude suitable for silicon carbide transistors, ensuring no temporal overlap between control signals to prevent short-circuiting and using a transformer with secondary windings to convert voltages, and a shift circuit with a Zener diode to produce a control voltage with opposite signs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a symmetrical drive voltage is used in current driver circuits, then the circuit design is simplified, but silicon carbide transistors are damaged
Solution Approach 1:
The patent applies asymmetry by generating an asymmetric drive voltage waveform with a positive voltage level (Vpp/2 + Voffset) and a negative voltage level (Vpp/2 - Voffset), where the magnitudes of positive and negative excursions are deliberately made unequal. This asymmetric waveform matches the specific voltage requirements of silicon carbide transistors, preventing damage while maintaining circuit functionality.
Solution Approach 2:
The patent changes the voltage parameters by introducing a configurable offset voltage (Voffset) that shifts the entire drive waveform. This parameter adjustment allows the drive voltage to be tailored to specific transistor requirements, transforming a potentially damaging symmetrical waveform into a safe asymmetric one without fundamentally redesigning the entire driver circuit.
2Stability of the object's composition
If control signals have temporal overlap, then the switching transitions are smoother, but short-circuiting occurs
Solution Approach 1:
The patent implements preliminary action by using a dead-time insertion mechanism that proactively prevents overlapping of complementary switch control signals. The dead-time circuit ensures that one switch is fully turned off before the other begins to turn on, eliminating the risk of shoot-through current while maintaining stable switching transitions through proper timing control.
3Reliability
If additional isolation components are added, then galvanic isolation is improved, but the design becomes less compact
Solution Approach 1:
The patent merges multiple functions into the transformer component, which simultaneously provides voltage conversion, galvanic isolation, and control signal transmission. By integrating these functions into a single transformer-based isolation stage, the patent achieves reliable galvanic isolation without adding separate isolation components, thereby maintaining design compactness.
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
The solution provides a safe and efficient control voltage for silicon carbide transistors, preventing damage and ensuring reliable operation by avoiding short-circuiting and resonance issues, while maintaining a compact design with galvanic isolation without additional components.
Implementation Method 1
a transformer connected to the switching assembly, the transformer comprising two secondary windings, the two secondary windings being connected to each other at a midpoint, the first secondary winding being designed to convert the first voltage to obtain a first converted voltage, The second secondary winding is designed to convert the first voltage to obtain a second converted voltage
Implementation Method 2
A rectifier circuit is designed to extract the like-signed portions of the first converted voltage and the opposite portions of the second converted voltage and to generate a third voltage from the extracted like-signed portions
Implementation Method 3
a shift circuit with a Zener diode to produce a control voltage with opposite signs
Data Source
Figure 1~2
Figure 3~8
Figure 9~12
AI summary
The invention relates to a device (12) for controlling a transistor (10), comprising: a separating assembly (16) for generating a first voltage (VC), a transformer (18) for obtaining a first and a second converted voltage (VD, VE) from the first voltage (VC), a rectifier circuit (20) for generating a third voltage (VF) from parts of the same sign of the first converted voltage (VD) and of the opposite of the second converted voltage (VE), a rocker (22) for generating a fourth voltage (VH) from the converted voltages (VD, VE), a switching assembly (24) for multiplying the third voltage (VF) with the fourth voltage (VH) normalised in order to obtain a multiplied voltage (VI), and a shifting circuit (26) for shifting the multiplied amplitude (VI) in order to obtain a control voltage.