Submodule Capacitor Charging Control for Electrical Converters
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Solution Overview
Problem
Existing converter arrangements face challenges in the start-up and charging behavior of capacitors in sub-modules, particularly in ensuring safe and efficient charging.
Innovation Solution
The arrangement includes a control device within each sub-module connected to a control unit, which controls switching elements and receives operating voltage from the sub-module's capacitor, with a switching device that switches the series circuit to a charging mode applying a higher series connection voltage than in normal operation, and transitions to normal mode once capacitors are sufficiently charged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a higher series voltage is applied to charge the capacitors in sub-modules, then the charging speed and efficiency are improved, but the risk of overcharging and damage to components increases
Solution Approach 1:
The patent implements dynamic switching between charging mode and normal operating mode based on real-time capacitor voltage status. The control unit monitors capacitor voltages and dynamically adjusts the switching device configuration: in charging mode, series connection applies higher voltage for fast charging; when capacitors reach target voltage, the system transitions to normal mode to prevent overcharging. This dynamic adaptation resolves the contradiction by allowing high voltage during charging while ensuring safety through automated mode transition.
Solution Approach 2:
The control unit receives feedback signals from voltage sensors monitoring capacitor voltages in each sub-module. Based on this feedback, the control unit determines when charging is complete and automatically switches from charging mode to normal operating mode. The feedback mechanism ensures that the higher charging voltage is applied only when needed and stopped precisely when capacitors are sufficiently charged, preventing damage while maximizing charging efficiency.
2Loss of time
If a special charging mode with higher voltage is implemented, then the start-up process is accelerated, but the device complexity increases due to additional switching configurations
Solution Approach 1:
The switching device is designed with multi-functionality, serving both as a charging mode switch and a normal operation switch. The same switching elements that connect sub-modules in series for charging also configure the circuit for normal operation. This universal design achieves fast start-up through higher voltage charging while avoiding additional dedicated components, thus reducing overall device complexity despite the dual-mode requirement.
Solution Approach 2:
The patent merges the charging function and normal operation function into a single integrated switching device system. Instead of having separate dedicated charging switches and operation switches, the same switching elements perform both functions by changing their connection configuration. This merging reduces the number of components needed while enabling accelerated start-up through the charging mode, effectively resolving the contradiction between speed and complexity.
3Use of energy by moving object
If the capacitors are charged in series connection with higher voltage, then the energy transfer efficiency is improved, but the control precision required increases to manage individual capacitor voltages
Solution Approach 1:
The control system is segmented into individual sub-module control units, each responsible for monitoring and controlling the capacitor voltage in its specific sub-module. Rather than one centralized controller managing all capacitors simultaneously, the segmentation allows distributed monitoring where each control unit independently tracks its local capacitor voltage. This segmentation simplifies the overall control task while maintaining precise voltage management during series charging, resolving the contradiction between efficient energy transfer and control complexity.
Solution Approach 2:
The control unit acts as an intermediary between the high-voltage charging process and the individual capacitor voltage monitoring. It receives voltage information from sensors, processes this data, and makes switching decisions based on aggregate capacitor status. This intermediary role simplifies the direct measurement complexity by providing a centralized intelligence layer that manages the distributed voltage monitoring task, enabling efficient series charging while keeping control implementation manageable.
Data Source
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AI summary
The invention relates to, inter alia, an arrangement (10) with at least one AC voltage connection (L1, L2, L3) to which an alternating current (Ie) can be supplied or from which an alternating current can be drawn, at least one series circuit (R) with at least two sub-modules (130) connected in series, and an actuator unit (30) for actuating the sub-modules (130). Each of the sub-modules (130) of the series circuit (R) comprises at least two switching elements (S1-S4) and a capacitor (C). According to the invention, each of the sub-modules (130) has a dedicated controller (150) which is connected to the actuator unit (30) and which actuates the respective switching elements (S1-S4) of the sub-module (130) and obtains the operating voltage of the sub-module from the respective capacitor (C), and the arrangement (10) has at least one switchover device (160-162, 190, 192) which is connected to the at least one series circuit (R) and which can switchover the series circuit voltage (Ur) applied to the series circuit (R) in a controlled manner by means of the actuator unit (30) and is switched to a charging mode after a startup process of the arrangement (10) in order to charge the capacitors (C) of the sub-modules (130), wherein the switchover device connects the at least one series circuit (R) differently in the charging mode than in a normal operating mode which follows the charging mode after the charging mode has been concluded.