Normally Closed Transistor Rectifier Startup Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power converters using normally closed transistors can short-circuit inputs and bus capacitors during startup or malfunctions, leading to voltage rise and auxiliary power system loading issues.
Innovation Solution
Incorporating a gate control device with a voltage rectifier element, capacitor, and resistor configuration for each transistor, along with a current limiting element, to prevent short-circuiting by ensuring transistors are blocked during startup or malfunctions, using field-effect transistors like JFETs made from silicon carbide or gallium nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If normally closed transistors are used in the rectifier switching arms, then high performance and efficiency are achieved, but short-circuiting of inputs and bus capacitor occurs during startup or malfunction
Solution Approach 1:
The patent applies preliminary action by pre-charging the bus capacitor through a dedicated pre-charging circuit before the normally closed transistors are activated. This ensures that when the converter starts up, the transistors are blocked and cannot cause short-circuiting, but once the bus voltage reaches a sufficient level, the transistors can be safely activated for normal operation.
Solution Approach 2:
The patent introduces an intermediary control mechanism - a control device with gate control circuits that mediate between the power source and the normally closed transistors. This control device actively manages the transistor states, blocking them during startup and enabling them during normal operation, thus preventing harmful short-circuiting while maintaining the performance benefits of normally closed transistors.
2Power
If normally closed transistors are used without control, then current flows freely, but voltage rise on power bus is prevented and auxiliary power system cannot be loaded
Solution Approach 1:
The patent applies dynamics by making the transistor states controllable rather than static. The normally closed transistors are equipped with gate control circuits that can dynamically switch them between blocked and conducting states based on the operational phase - blocked during startup to allow voltage rise, and conducting during normal operation to enable power transfer and load the auxiliary power system.
3Object-affected harmful factors
If gate control devices are added to control normally closed transistors, then short-circuiting is prevented, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the control function into separate gate control circuits for each transistor or switching arm. This modular approach allows independent control of each transistor, preventing short-circuiting through localized control while maintaining overall system manageability. Each gate control circuit is a self-contained unit that can be designed and implemented independently.
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
Prevents short-circuiting of inputs and bus capacitors, ensuring safe startup and operation by controlling the gate-source voltage to keep transistors off until the DC voltage reaches a sufficient level, thereby maintaining power bus stability.
Implementation Method 1
a voltage rectifier element connected between the output of the control device and an input of the converter
Implementation Method 2
a bus capacitor connected between the positive line and the negative line of the power supply bus and intended to keep the DC voltage on the bus constant
Data Source
Figure 1~4
Figure 2
Figure 3~5
AI summary
The invention relates to a power converter comprising, in particular, a rectifier having at least one switching arm with two transistors (T1-T6) connected in series. The transistors (T1-T6) are normally closed field-effect transistors, for example JFETs, and are each controlled by a gate driver (CT1-CT6). Each gate driver comprises, in particular: - an output (OUT1) connected to the gate (G) of the controlled transistor, - a voltage rectifier element connected between the output of the driver and an input (in1, in3) of the converter, - a capacitor (C11) connected between the source (S) of the transistor and a point located between the output of the driver and the voltage rectifier element.