Capacitor Voltage Balancing Device for Inverter Systems
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Solution Overview
Problem
Existing voltage balancing devices for capacitors in multi-level voltage inverters are ineffective at balancing electrical charges when the amplitude of the AC output voltage exceeds a quarter of the DC input voltage, leading to voltage imbalances across capacitor terminals, especially in high-voltage applications.
Innovation Solution
A balancing device with a temporary electrical energy storage element and guided current means to extract or inject charges from intermediate points, controlled to balance voltage across capacitors, connected between the input terminals and capable of determining charge excess or deficits, using switches and diodes to manage energy storage and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the amplitude of AC output voltage is increased beyond a quarter of DC input voltage, then the voltage conversion capability is improved, but the existing balancing means become ineffective and voltage imbalance occurs across capacitor terminals
Solution Approach 1:
The patent introduces a temporary electrical energy storage element as an intermediary between the capacitor assembly and the voltage conversion device. This mediator temporarily stores electrical energy and releases it to balance voltage imbalances that occur when the AC output voltage amplitude exceeds the conventional limit, enabling high voltage conversion while maintaining capacitor voltage balance.
Solution Approach 2:
The patent changes the operational parameters by introducing a temporary energy storage mechanism that dynamically adjusts to voltage imbalances. The control member monitors voltage levels across capacitors and activates the temporary storage element when imbalances are detected, allowing the system to operate beyond traditional voltage limits while maintaining stability.
2Stability of the object's composition
If capacitors of significant size are used to limit voltage variation at the midpoint, then voltage stability is improved, but the device size and cost increase
Solution Approach 1:
The patent segments the energy storage function into two parts: the permanent capacitor assembly that provides baseline voltage stability, and a temporary electrical energy storage element that provides supplemental balancing. This segmentation allows smaller permanent capacitors to be used while maintaining voltage stability through the coordinated action of both energy storage components.
Solution Approach 2:
The temporary electrical energy storage element acts as an intermediary that supplements the permanent capacitors, allowing them to be smaller in size. This mediator handles the transient energy balancing, reducing the burden on the permanent capacitors and enabling reduced capacitor sizing while maintaining voltage stability.
3Reliability
If a temporary electrical energy storage element is added to balance voltage, then voltage balance capability is improved, but the device complexity increases
Solution Approach 1:
The temporary electrical energy storage element serves multiple functions: it stores electrical energy, balances voltage imbalances across capacitors, and enables the system to operate beyond traditional voltage limits. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall device complexity.
4Device complexity
If the capacitance value is reduced to decrease device size, then device compactness is improved, but voltage variation at the midpoint increases
Solution Approach 1:
The temporary electrical energy storage element serves as a mediator that compensates for the reduced capacitance of smaller permanent capacitors. When voltage variations occur due to reduced capacitance, the temporary storage element dynamically stores or releases energy to maintain voltage balance, enabling compact device design without sacrificing voltage stability.
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
The solution effectively balances voltage across capacitors regardless of the voltage and current amplitude, ensuring stable operation even at high voltage levels by dynamically managing charge distribution and storage.
Implementation Method 1
a temporary electrical energy storage element (34)
Data Source
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AI summary
The invention relates to a device for balancing the voltage at the terminals of at least one capacitor (28) of a capacitor assembly (22) comprising N-1 capacitors (28) which are connected in series between a positive input terminal (16) and a negative input terminal (18) and which are connected together by intermediate points (30), N being greater than or equal to 3, wherein said balancing device includes at least one balancing module (24) connected between both input terminals. The balancing module(s) comprise a means (32) for determining the amount of excess or missing charges at each of the intermediate points, a temporary electrical power storage element (34) comprising two terminals (45, 46), a first current-guiding means (40) capable of extracting electrical charges from an intermediate point and providing same to a terminal of the storage element, a second current-guiding means (42) capable of feeding electrical charges from the other terminal of the storage element to an intermediate point, and a member (44) for controlling the first and second guiding means capable of controlling the first means so as to extract charges from at least one intermediate point, and capable of controlling the second means so as to feed the charges to at least one intermediate point.