MMC Recharging Circuit for Floating Switch Gate Power
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Solution Overview
Problem
Existing methods for driving power semiconductor switches in modular multi-level converters face challenges due to fluctuations in source potential and the inability to use bootstrapping in certain circuit configurations, leading to inefficiencies and the need for expensive DC-DC converters.
Innovation Solution
A method and circuit for recharging an energy store used to drive power semiconductor switches, where the energy store and switch are at the same potential, allowing the controller to manage charging based on switching states to avoid the use of complex DC-DC converters, utilizing a bootstrap capacitor or other energy stores like batteries, and employing a charging switch to prevent charge draining when the switch potential is not at ground potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bootstrapping is used to charge the energy store, then the circuit configuration is simplified, but bootstrapping cannot be used in certain circuit configurations where the source potential fluctuates
Solution Approach 1:
The patent introduces a charging switch as an intermediary component between the supply voltage and the energy store. This charging switch is controlled by a controller that monitors the source potential of the power semiconductor switch. When the source potential equals the ground potential, the charging switch closes to charge the energy store; when they differ, the charging switch opens to prevent improper charging. This intermediary mechanism enables proper energy store charging in circuit configurations where traditional bootstrapping fails.
2Reliability
If expensive DC-DC converters are used to drive power semiconductor switches with fluctuating source potential, then reliable switching is achieved, but system cost and complexity increase
Solution Approach 1:
The patent implements a self-service mechanism where the controller monitors the source potential of the power semiconductor switch and automatically controls the charging switch to charge or discharge the energy store as needed. The system uses its own operational state information (source potential) to manage the energy store charging, eliminating the need for external DC-DC converters. This self-service approach maintains reliable switching while reducing system complexity and cost.
3Use of energy by moving object
If the charging switch remains closed to charge the energy store, then the energy store is continuously charged, but charge draining occurs when the switch potential is not at ground potential
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the source potential of the power semiconductor switch and uses this information to control the charging switch state. When the source potential equals the ground potential, the controller closes the charging switch to charge the energy store. When the source potential differs from ground potential, the controller opens the charging switch to prevent charge draining. This feedback-based control ensures efficient energy storage while preventing energy loss.
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
This approach enables efficient driving of power semiconductor switches without the need for expensive DC-DC converters, maintaining efficient operation even in configurations where bootstrapping is not feasible, thereby extending the lifespan of insulation and reducing losses in AC voltage supply systems.
Implementation Method 1
an energy store, in particular a bootstrap capacitor, used to drive the power semiconductor switch
Implementation Method 2
by driving at least one charging switch, charging of the energy store is activated as soon as the potential value of the energy store corresponds to a ground potential
Data Source
AI summary
The present invention relates to a method for recharging an energy store (102) used to drive a power semiconductor switch (100), wherein the energy store (102) and the power semiconductor switch (100) are at the same potential, wherein a switching state of the power semiconductor switch (100) is effected by a controller (204, 712), wherein the controller (204) assigns a respective potential value to the energy store (102) at a respective switching state (202) and wherein, by driving at least one charging switch (112, 114, 122, 132, 142, 152), charging of the energy store (102) is activated as soon as the potential value of the energy store (102) corresponds to a ground potential of a supply voltage (106, 216).