Inverter Voltage Node Balancing via Switched-Mode Power Supply
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Solution Overview
Problem
Inverters with intermediate circuits face challenges in maintaining constant voltage nodes due to asymmetries caused by parameter differences in capacitors and semiconductor components, leading to inefficiencies and potential system failures, with existing solutions either resulting in significant power losses or high circuit complexity and costs.
Innovation Solution
A power electronic arrangement with a series-connected intermediate circuit and a switched-mode power supply connected in parallel with one capacitor, utilizing a DC voltage controller to balance energy between capacitors, reducing losses and complexity while utilizing energy asymmetries effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a high-impedance resistor is connected in parallel with each intermediate circuit capacitor to balance voltage nodes, then voltage balancing is achieved, but permanent power loss occurs and inverter efficiency is reduced
Solution Approach 1:
The patent implements periodic action by using pulse-width modulation (PWM) to switch the transistor on and off at specific intervals. The transistor is activated only when voltage imbalance is detected, creating periodic corrective action rather than continuous operation. This allows the system to maintain voltage balance while minimizing energy dissipation, as the high-impedance resistor is effectively bypassed during normal operation and only engages periodically when needed for correction.
Solution Approach 2:
The system employs self-service by using the existing voltage asymmetry and power differences in the intermediate circuit capacitors to automatically trigger the balancing mechanism. The control unit continuously monitors voltage levels and activates the transistor only when imbalance occurs, allowing the system to self-regulate without external intervention. This approach converts the naturally occurring power differences into useful balancing action rather than treating them purely as losses.
2Use of energy by moving object
If a transistor is connected in series with a high-impedance resistor to enable selective current flow for balancing, then energy consumption is reduced, but energy differences are still converted into heat
Solution Approach 1:
The patent applies the 'blessing in disguise' principle by converting the harmful effect of voltage asymmetry and power differences into a beneficial balancing mechanism. Instead of treating the natural voltage imbalances and power differences as mere losses to be minimized, the system uses them as triggers to activate the transistor and high-impedance resistor only when needed. This transforms what would otherwise be continuous energy waste into a targeted corrective action that eliminates imbalance without sustained heat generation.
3Stability of the object's composition
If classic voltage regulator arrangements are used to maintain constant voltage nodes, then voltage stability is achieved, but circuit complexity and costs increase significantly
Solution Approach 1:
The patent extracts only the essential elements needed for voltage balancing from a classic voltage regulator architecture. Instead of implementing a full voltage regulator system with multiple components and control circuits, the invention isolates and utilizes specifically the transistor and high-impedance resistor in series with the intermediate circuit capacitors. This extracted approach maintains voltage stability functionality while eliminating unnecessary circuit complexity and associated costs.
Solution Approach 2:
The system achieves multi-functionality by having the transistor and high-impedance resistor serve dual purposes: they act as a switching element for PWM control and simultaneously function as a voltage balancing mechanism. The control unit integrates voltage monitoring and balancing control functions, allowing a single circuit element to perform multiple roles that would traditionally require separate components in a classic voltage regulator arrangement.
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 solution achieves low-loss, cost-effective balancing of voltage nodes with simplified control, improving efficiency and reducing circuit complexity compared to existing methods.
Implementation Method 1
a switched-mode power supply (SNT), which is connected in parallel with one of the capacitors (2) and has an energy balance between the two capacitors inducing DC voltage controller
Implementation Method 2
an intermediate circuit with two capacitors (1, 2) connected in series
Data Source
Figure 1~2
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Figure 4
AI summary
The invention relates to an electronic power assembly, such as an inverter, which has an intermediate circuit having two or more capacitors connected in series. According to the invention, a voltage node is located between the capacitors. A switching power supply is connected in parallel to one of the capacitors of the intermediate circuit. The inverter further has a direct voltage actuator connected to the two capacitors and the voltage node, which direct voltage actuator induces energy equalization between the two capacitors.