DC Power Supply Capacitor Charging Control for Overcurrent Prevention
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Solution Overview
Problem
Conventional DC power-supply devices with booster circuits face issues of device stoppage and voltage unbalance due to excessive short-circuit currents, leading to unnecessary operation of overcurrent protection circuits, which increases costs and requires high-capacity switching elements.
Innovation Solution
A DC power-supply device configuration that includes a reactor, serially connected switching elements, capacitors, and a diode to prevent backflow, with a control unit that adjusts the charging frequency based on the operating conditions of the load to prevent overcurrent protection activation, allowing stable operation while minimizing cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching elements are driven simultaneously to achieve desired output voltage, then the output voltage control is improved, but excessive short-circuit current flows causing overcurrent protection activation and device stoppage
Solution Approach 1:
The patent applies dynamics by making the switching elements operate at different timings rather than simultaneously. The first switching element is turned on before the second switching element, creating a staged switching sequence that dynamically controls current flow to prevent excessive short-circuit current while maintaining output voltage control.
Solution Approach 2:
The patent uses periodic action through PWM (pulse width modulation) control where the switching elements are turned on and off in periodic cycles with specific duty ratios. This periodic switching allows control of output voltage while preventing continuous short-circuit current by introducing timing intervals between switching operations.
2Quantity of substance
If the protection level of the overcurrent protection circuit is increased to allow simultaneous on-state of switching elements, then the current capacity is improved, but a switching element with large allowable current is required causing cost increase
Solution Approach 1:
The patent reduces current capacity requirements by implementing dynamic timing control where switching elements are activated sequentially rather than simultaneously. This staggers the current demand, allowing the use of switching elements with smaller allowable current ratings while still achieving the required total current capacity through coordinated operation.
3Reliability
If the overcurrent protection circuit operates to prevent overcurrent, then the switching elements are protected, but the operation of switching elements stops causing device stoppage
Solution Approach 1:
The patent applies preliminary action by implementing timing control that prevents excessive current from occurring in the first place. By turning on switching elements at different timings, the system proactively avoids generating short-circuit current that would trigger overcurrent protection, thereby maintaining continuous operation without device stoppage.
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 prevents unnecessary overcurrent protection operations, ensuring stable device operation and reducing costs by optimizing the switching frequency and charging patterns, thereby maintaining efficient power supply to the load.
Implementation Method 1
a reactor connected to an input side or an output side of the rectifier circuit
Implementation Method 2
a diode that prevents backflow from the capacitors
Data Source
AI summary
The DC power-supply device includes a rectifier circuit rectifying an alternating current, a reactor connected to an input or output side of the rectifier circuit, a first capacitor and a second capacitor serially connected between output terminals to a load, and a charging unit that selectively charges one or both of the first capacitor and the second capacitor. A ratio, to a period obtained by combining a charging period and a non-charging period of a pair of the first capacitor and the second capacitor, of the non-charging period, is controlled according to an operating condition of the load, to change a charging frequency of the first capacitor and the second capacitor based on the ratio, at the time of controlling an output voltage to the load.