Switching Power Supply Phase Control Efficiency
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Solution Overview
Problem
Existing switching power-supply devices face efficiency issues when input voltage is lowered, as the frequency control methods lead to a narrowed conduction angle and increased current effective value, resulting in reduced efficiency.
Innovation Solution
A switching power-supply device with a transformer, series resonance circuits, and a control unit that maintains the same frequency for switching signals across series circuits while controlling the phase difference between them, optimizing the conduction angle and efficiency by alternately turning on/off switching elements with dead time, and using a detection circuit to adjust frequencies when the output voltage falls below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the frequency of the switching signal is increased to approximate the resonance frequency when input voltage is lowered, then the output voltage is increased, but the conduction angle of load current is narrowed and current effective value is increased, resulting in remarkably lowered efficiency
Solution Approach 1:
The patent changes the control parameter from frequency adjustment to phase difference adjustment. By maintaining a constant switching frequency and instead varying the phase difference between switching signals of multiple series circuits, the system can regulate output voltage without entering resonance conditions that cause excessive current effective values and efficiency degradation.
2Stress or pressure
If the frequency of the switching signal is changed to control output voltage, then the output voltage is adjusted, but the stability of switching frequency is compromised
Solution Approach 1:
The patent divides the power conversion system into multiple independent series circuits (first series circuit with first and second switching elements, third series circuit with fourth and fifth switching elements, etc.). Each circuit operates at the same switching frequency but with controlled phase differences between them. This segmentation allows frequency stability to be maintained while achieving voltage control through phase manipulation.
Solution Approach 2:
The patent introduces dynamic phase difference control between multiple switching circuits. By dynamically adjusting the phase difference between switching signals of different series circuits based on output voltage requirements, the system achieves flexible voltage regulation while keeping the fundamental switching frequency constant and stable.
3Loss of energy
If multiple switching elements are operated alternately with dead time, then the conduction angle is optimized and efficiency is improved, but the control complexity increases
Solution Approach 1:
The patent employs periodic alternating operation of multiple switching elements within each series circuit (first and second switching elements alternate, fourth and fifth switching elements alternate). This periodic action with built-in dead times ensures continuous current flow while preventing simultaneous conduction of series elements. The phase difference between different series circuits is also controlled periodically to achieve the desired output voltage while maintaining efficiency.
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 approach allows for effective voltage control, improved efficiency, and enhanced reliability by maintaining optimal conduction angles and phase differences, even under varying load conditions, and reduces the impact of frequency changes on output voltage stability.
Implementation Method 1
a transformer having a primary coil and a secondary coil that is magnetically coupled with the primary coil
Implementation Method 2
a series resonance circuit including a capacitor connected to one end of the second switching element and the primary coil connected between the capacitor and the other end of the second switching element
Data Source
AI summary
A switching power-supply device includes: a first series circuit including a first switching element; and a second switching element, a second series circuit including a third switching element and a fourth switching element; and a control unit that, while making frequencies of switching signals of the first series circuit and the second series circuit be the same, performs control of turning on-and-off the first switching element and the second switching element, alternately, with dead time at which the first switching element and the second switching element become off and turning on-and-off the third switching element and the fourth switching element, alternately, with dead time at which the third switching element and the fourth switching element become off, wherein the control unit controls a phase difference between the switching signal of the first series circuit and the switching signal of the second series circuit.