3-Terminal Static DC Transformer Startup via Integrated Capacitor Charging
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Solution Overview
Problem
Conventional three-terminal static DC converters require separate circuits or devices for charging, leading to increased device size and cost, and pose safety risks during activation.
Innovation Solution
A control device that integrates a three-winding wire high-frequency transformer and an arithmetic circuit to manage the charging of DC capacitors within the main circuit, using on-pulse signals to control self-extinguishing elements and diodes, ensuring safe activation without external charging circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate charging circuits or devices are used to charge DC capacitors before activation, then the DC capacitors can be charged safely, but the device size and product cost increase
Solution Approach 1:
The patent merges the charging function into the main circuit by using the bridge circuits and self-extinguishing elements to charge the DC capacitors during normal operation, eliminating the need for separate pre-charging circuits or devices. This integration resolves the contradiction by maintaining safe charging capability while reducing device size and complexity.
Solution Approach 2:
The bridge circuits and self-extinguishing elements are designed to serve dual purposes: they function as the main power conversion circuit during normal operation and simultaneously serve as the charging circuit for DC capacitors during activation. This multi-functionality eliminates separate charging components while ensuring safe activation.
2Reliability
If separate charging circuits or devices are used to charge DC capacitors before activation, then the DC capacitors can be charged safely, but the product cost increases
Solution Approach 1:
The patent combines the charging function with the main circuit components, eliminating the need for separate pre-charging circuits or devices. This integration reduces the total component count and manufacturing complexity, thereby lowering product cost while maintaining safe activation capability.
Solution Approach 2:
The bridge circuits and self-extinguishing elements perform multiple functions including power conversion and capacitor charging. This multi-functionality reduces the overall component requirements and manufacturing cost while ensuring reliable activation.
3Reliability
If resistors are inserted into the main circuit for charging, then the DC capacitors can be charged with limited current, but the resistors must be short-circuited after charging which adds control complexity
Solution Approach 1:
The patent employs self-extinguishing elements that automatically control the charging current through their inherent current-limiting characteristics during the charging phase, and then automatically transition to their normal switching function. This self-service mechanism eliminates the need for external resistors and complex short-circuiting control, reducing overall control complexity while maintaining reliable current control.
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 safe activation of the three-terminal static DC converter while minimizing device size and cost, by integrating charging functionality within the main circuit and controlling current peaks to prevent damage to self-extinguishing elements.
Implementation Method 1
a three-winding wire high-frequency transformer
Implementation Method 2
self-extinguishing semiconductor devices in which their ON/OFF can be arbitrarily switched based on external signals
Implementation Method 3
converts DC into a high-frequency AC voltage, boosts or drops the high-frequency AC voltage via an AC converter, and thereafter once again converts the AC voltage into DC
Data Source
Figure 1
Figure 2
Figure 3(A)~3(E)
AI summary
Proposed is a control device capable of safely activating a three-terminal static DC converter while suppressing the increase in the size of the device comprising the three-terminal static DC converter as well as the increase in product cost. In a control device which controls a drive of a static DC converter in which three or more self-excited single phase inverters, to which DC capacitors are respectively connected in parallel, are connected via a high frequency transformer, provided are a detector which detects a voltage of each of the DC terminals in a state where a DC voltage is applied to one of the DC terminals and that DC terminal is maintained at a fixed voltage, a minimum voltage terminal selection circuit which selects the DC terminal with a lowest voltage among the DC terminals to which the DC voltage has not been applied based on a detection result of the detector, and an arithmetic circuit which generates, in the self-excited single phase inverter to which the DC voltage has been applied, an AC voltage of a size that is comparable to a difference between the voltage of the DC terminal to which the DC voltage has been applied and the voltage of the DC terminal selected by the minimum voltage terminal selection circuit.