Power Converter Precharge Control With Dynamic Voltage Thresholds
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Solution Overview
Problem
Existing power conversion systems face challenges in setting a desirable charge characteristic for the precharge operation with a simple configuration, leading to prolonged charging times and variable voltage gradients due to capacitor capacitance variations.
Innovation Solution
A power conversion apparatus and system that utilize a control circuit to generate adjustable thresholds and duty ratios for switching circuits and rectifying circuits, controlling the precharge operation to set a predictable voltage range and reduce inrush currents through intermittent switching based on voltage comparisons and hysteresis control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional precharge operation control is used, then the precharge process can be performed, but the charging time is long and the configuration becomes complex due to varying capacitance values
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the threshold voltage value during the precharge operation. The control circuit changes the threshold from an initial value to a final value based on the charging progress, which simplifies the control configuration while reducing precharge time. This is achieved by comparing the capacitor voltage against a time-varying threshold rather than using complex multi-stage control circuits.
2Object-affected harmful factors
If the precharge operation is performed without optimized threshold control, then the system can operate, but inrush currents are not effectively reduced and thermal stress on components increases
Solution Approach 1:
The patent applies preliminary action by setting an initial threshold voltage value that is lower than the final threshold. This initial lower threshold allows the precharge operation to start with reduced current flow, preventing inrush currents before they occur. The threshold then increases to the final value to complete the charging process, achieving both current limiting and efficient charging.
3Manufacturing precision
If fixed threshold control is used in precharge operation, then the control circuit is simple, but the charging characteristic cannot be precisely controlled and charging time is extended
Solution Approach 1:
The patent applies dynamics by making the threshold voltage a dynamic parameter that changes during operation. The control circuit transitions the threshold from an initial value to a final value based on the charging progress, enabling precise control of the charge characteristic. This dynamic adjustment allows the system to optimize charging speed at different stages without requiring complex external control circuits.
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 allows for a simple configuration to set a consistent and efficient precharge operation, reducing charging time and current stress by controlling voltage within predetermined thresholds, thereby optimizing the precharge process.
Implementation Method 1
a transformer (13) including a primary winding (13A) and a secondary winding (13B)
Implementation Method 2
a capacitor (9) having one end coupled to the terminal (T11) of the power conversion apparatus (10) and to the switch (SW1), and the other end coupled to the terminal (T12) of the power conversion apparatus (10) and to the switch (SW2)
Data Source
AI summary
A power conversion apparatus includes: a first power terminal; a switching circuit including first switching devices configured to be turned on/off based on a first driving signal; a transformer; a rectifying circuit including second switching devices configured to be turned on/off based on a second driving signal; a smoothing circuit; a second power terminal; and a control circuit. In a first period before electric power is supplied from the first power terminal toward the second power terminal, the control circuit generates a first threshold increasing with the passage of time, and performs, when a voltage value of a voltage at the first power terminal reaches the first threshold, switching from an output state in which the second driving signal is outputted to an output stop state in which output of the second driving signal is stopped, or switching from the output stop state to the output state.