DC Power Supply Capacitor Voltage Balancing Control
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Solution Overview
Problem
Conventional DC power supply systems experience voltage imbalance across series-connected capacitors due to dispersion in component characteristics and operating signals, leading to potential operational interruptions.
Innovation Solution
A DC power supply system with series-connected switching elements and reactors, along with anti-parallel diodes and capacitors, operates in multiple modes to control reactor current flow and utilize a balancer circuit to maintain voltage balance across capacitors, ensuring balanced voltages are supplied to the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DC power supply systems are used with series-connected capacitors, then the system structure is simple and cost-effective, but voltage imbalance occurs across the capacitors due to component dispersion and load imbalance
Solution Approach 1:
The patent implements a feedback control mechanism where voltage detection circuits continuously monitor the voltages across both capacitors, and the control circuit adjusts the ON-OFF timing of switching elements based on detected voltage differences. This closed-loop feedback system dynamically compensates for voltage imbalance caused by component dispersion and load variations, maintaining reliable voltage balance without requiring complex hardware modifications
Solution Approach 2:
The system utilizes the existing reactor and switching elements to achieve voltage balance through self-regulating control. The control circuit automatically adjusts the switching duty cycles based on voltage detection, allowing the system to self-correct voltage imbalance without external intervention or complex additional components, thereby maintaining simplicity while improving reliability
2Reliability
If voltage detection and control circuits are added to maintain capacitor voltage balance, then voltage balance reliability improves, but the device complexity and cost increase
Solution Approach 1:
The control circuit performs multiple functions using the same components: it detects voltages across both capacitors, determines which capacitor has higher voltage, generates appropriate PWM signals, and controls the switching elements. The reactor serves both as an energy storage element and as a means to couple the switching elements. This multi-functional approach achieves voltage balance without requiring separate dedicated circuits for each function, minimizing added complexity
Solution Approach 2:
The system maintains voltage balance by dynamically changing the duty cycle parameters of the switching elements. By adjusting the ON-OFF timing ratios based on detected voltage differences, the control circuit compensates for component variations and load imbalances. This parameter-based control approach is more efficient than hardware modifications and reduces overall system complexity while improving reliability
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 system effectively maintains balanced voltages across capacitors, even under conditions of component imbalance and varying load demands, preventing operational interruptions and ensuring stable power supply.
Implementation Method 1
transfer magnetic energy stored in the first and the second reactors to the first and the second capacitors to charge the capacitors
Implementation Method 2
series-connected first, second, third and fourth switching elements each having an anti-parallel-connected diode
Data Source
AI summary
A DC power supply system delivers a DC output that has a neutral point and is higher than the input voltage of a single DC power supply, by a circuit with series-connected switching elements. The DC power supply system addresses the problem of imbalance between the voltage between a positive terminal and the neutral point and the voltage between a negative terminal and the neutral point. In operational control of the DC power supply system, a capacitor voltage between the neutral point and the positive terminal and a capacitor voltage between the neutral point and the negative terminal are compared, and four switching elements are operated to equalize the two capacitor voltages.