Converter Module Pre-Charging via Switch-On Unit
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Solution Overview
Problem
Existing multi-level converter modules face reliability issues during commissioning due to the inability to guarantee pre-charging of energy stores when the control device's energy supply is inactive, particularly when the bidirectional switch is locked in its initial position.
Innovation Solution
Incorporating a switch-on unit that generates a switch-on voltage from the voltage drop across the bidirectional switch, allowing the bidirectional switch to be turned on independently in either direction, and a deactivation switch to decouple the switch-on unit from the control device during normal operation once the energy store is charged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control device's power supply is derived from the energy storage unit, then the control device can be powered during normal operation, but the pre-charging of the energy storage unit cannot be guaranteed when the bidirectional switch is locked in its initial position
Solution Approach 1:
The patent introduces a preliminary action by providing a dedicated pre-charging path for the energy storage unit that operates independently of the control device's power supply. This pre-charging circuit allows the energy storage unit to be charged before the control device becomes active, resolving the contradiction by ensuring that the necessary energy is available in the storage unit before normal operation begins.
Solution Approach 2:
The patent employs an intermediary element - a separate pre-charging power supply or circuit - that mediates between the external power source and the energy storage unit. This intermediary pre-charging path allows energy transfer without requiring the control device to be active, thus solving the problem of initial commissioning while maintaining the normal power derivation relationship during operation.
2Reliability
If the bidirectional switch is locked in its initial position, then the converter module can start up, but the pre-charging of the energy storage unit cannot be guaranteed
Solution Approach 1:
The patent segments the switching control into distinct functional parts: a pre-charging phase with simplified control that guarantees energy storage charging, and a normal operation phase with full bidirectional switch control. This segmentation allows the system to ensure reliable pre-charging without requiring complex coordinated control of all switching elements simultaneously.
Solution Approach 2:
The patent implements preliminary action by establishing a dedicated pre-charging path that operates before the full switching control system is activated. This preliminary pre-charging phase ensures the energy storage unit is properly charged while keeping the switching control relatively simple, avoiding the need for complex coordinated control during the initial commissioning phase.
3Reliability
If a switching unit is added in parallel to the bidirectional switch to generate switch-on voltage, then the bidirectional switch can be switched on reliably, but the device complexity increases
Solution Approach 1:
The patent merges the switching unit that generates switch-on voltage with the existing bidirectional switch structure. By integrating these functions into a combined unit, the patent achieves reliable bidirectional switch operation while minimizing the increase in overall device complexity. The merged structure allows voltage generation and switch control to work together efficiently without requiring entirely separate components.
Solution Approach 2:
The switching unit is designed to generate the switch-on voltage automatically from the voltage drop across the bidirectional switch itself. This self-service mechanism eliminates the need for external power supplies or complex control circuits to provide the switching voltage, thereby improving reliability while keeping the added complexity minimal. The system essentially uses its own operating voltage to enable switching.
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
Ensures reliable operation of the multi-level converter by enabling pre-charging of energy stores and maintaining control over the bidirectional switch, even in the absence of an active energy supply to the control device.
Implementation Method 1
The switch-on voltage is generated by dividing the voltage drop across the bidirectional switch. This provides a particularly simple way to generate the switch-on voltage required to activate the bidirectional switch. The voltage division is implemented using a voltage divider circuit connected in parallel with the bidirectional switch.
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a converter module (10) for a multi-stage converter (1), comprising an energy store (14) connected in parallel with a series circuit of a first and a second semiconductor switching unit (15, 16), wherein at least one of the semiconductor switching units has a bidirectional switch (19). The invention is characterized by a switch-on unit (20) connected in parallel with the bidirectional switch, by means of which switch-on unit a switch-on voltage for switching on the bidirectional switch can be produced from a voltage dropping across the bidirectional switch. The invention further relates to a multi-stage converter (1) having the converter module (10) according to the invention and to a method for operating the converter module (10).