Gate Drive Circuit Parasitic Coupling Reduction
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Solution Overview
Problem
Conventional power conversion systems face challenges in providing precise synchronization for controlling series connected power semiconductor devices in high voltage environments with significant voltage change rates, leading to parasitic currents and potential device failure.
Innovation Solution
A drive circuit utilizing a first transformer unit connected with a pulse amplifier module and a second transformer unit, each with multiple windings, provides voltage isolation and reduces parasitic coupling by increasing common mode impedance, thereby minimizing capacitance between control and power semiconductor groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is used to provide voltage isolation and control functionality, then galvanic isolation is achieved, but parasitic currents flow through the control circuit due to common voltage produced during voltage steps
Solution Approach 1:
The patent divides the transformer isolation system into multiple separate transformer units (first transformer unit and second transformer unit) rather than using a single transformer. This segmentation isolates different parts of the control circuit, preventing parasitic currents from flowing through the entire control path during voltage transitions, thus maintaining voltage isolation while eliminating harmful parasitic effects.
Solution Approach 2:
The patent introduces an intermediary capacitor connected between the primary and secondary windings of the transformers. This capacitor acts as a mediator that blocks the propagation of common-mode voltage spikes and parasitic currents while allowing the isolation function to remain effective. The capacitor serves as an intermediate element that prevents direct coupling of harmful transient voltages.
2Reliability
If fiber optic transmission is used for creating digital on-off signals with isolated power source, then galvanic isolation is achieved, but precise synchronization for controlling series connected power semiconductor devices is lost
Solution Approach 1:
The patent replaces fiber optic transmission with an electrical transformer-based signal transmission system. This substitution allows the use of electrical fields and magnetic coupling to transmit control signals while maintaining galvanic isolation through the transformer cores. The electrical system provides inherent synchronization through the coupled magnetic fields, eliminating the timing uncertainties associated with optical transmission.
Solution Approach 2:
The patent changes the transmission medium from optical to electrical/magnetic domain while maintaining isolation through transformer coupling. By operating in the electrical domain with properly designed transformer parameters (inductance, capacitance, coupling coefficients), the system achieves both galvanic isolation and precise synchronization through the inherent electromagnetic coupling between primary and secondary windings.
3Object-generated harmful factors
If additional transformer units are added in series between primary and secondary windings, then parasitic coupling is reduced, but capacitance is added to the electrical system
Solution Approach 1:
The patent carefully selects and optimizes the capacitance values of the blocking capacitors introduced in the multi-transformer configuration. By choosing appropriate capacitance values that are sufficiently large to block parasitic coupling but sufficiently small to minimize their impact on the overall system, the patent achieves reduced parasitic coupling without significantly increasing total system capacitance. The parameter optimization balances these competing requirements.
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 ensures precise synchronization and reduces parasitic coupling, preventing unintended operation and device failure in high voltage environments by decreasing capacitance and increasing common mode impedance, thus enhancing system reliability.
Implementation Method 1
The first and second transformers provide voltage isolation and reduce parasitic coupling between the control module and the pulse receiver module
Implementation Method 2
With each additional transformer added in series between the first primary winding and last secondary winding, additional capacitance is added to the electrical system. Therefore, the collective capacitance between the first primary and the last secondary windings is decreased
Data Source
AI summary
A drive circuit including a first transformer unit in connection with a pulse amplifier module and a second transformer unit in connection with a plurality of power semiconductor groups, each group containing one or more power devices. The first transformer unit includes at least one primary transformer configured to receive a current pulse at a primary winding from a current pulse generation module, the current pulse being reflected to a secondary winding. The second transformer unit includes a plurality of secondary transformers where each secondary transformer is configured to receive the current pulse at a primary winding thereof, the current pulse being reflected to a secondary winding coupled to a pulse receiver module. The first and second transformer units reduce parasitic coupling between the pulse receiver module and the control module.