Switching Power Supply Reverse Recovery Current Suppression
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Solution Overview
Problem
Existing switching power supply apparatuses suffer from high power loss in the resistor of the CR snubber circuit, limiting power conversion performance due to large reverse recovery current during diode reverse recovery time.
Innovation Solution
Incorporating a second rectifying element with a shorter reverse recovery time connected in parallel with a second inductor in the conduction path, which suppresses the peak value of reverse current, thereby reducing power loss and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a CR snubber circuit is used to suppress reverse recovery current noise, then noise is reduced, but power loss in the resistor increases
Solution Approach 1:
The invention changes the key parameter of the rectifying element from a diode with conventional reverse recovery time to a diode with extremely short reverse recovery time (practically zero). This parameter change eliminates the reverse recovery current that causes both noise and power loss in the CR snubber circuit, allowing the snubber to be removed or minimized while achieving both low noise and low power loss.
Solution Approach 2:
By using a diode with practically zero reverse recovery time, the invention extracts or removes the harmful reverse recovery current component from the circuit. This eliminates the need for the CR snubber circuit's resistor component, thereby removing the source of power loss while maintaining noise suppression functionality through the inductor alone.
2Device complexity
If a diode with conventional reverse recovery time is used, then the circuit is simple, but reverse recovery current causes power loss
Solution Approach 1:
The invention changes the reverse recovery time parameter of the diode from conventional values to practically zero. This parameter change directly eliminates the reverse recovery current that causes power loss, while the circuit structure remains relatively simple with the addition of only one inductor in series with the diode.
3Object-affected harmful factors
If an inductor is connected in series with the diode to reduce reverse recovery current, then noise is suppressed, but the circuit complexity increases
Solution Approach 1:
The invention extracts the noise suppression function from the CR snubber circuit and implements it solely through the inductor Ld connected in series with the diode. By using a diode with practically zero reverse recovery time, the circuit eliminates the need for the capacitor and resistor components, achieving noise suppression with minimal circuit complexity.
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 effectively minimizes power loss due to reverse current, enhancing power conversion efficiency by using a high-speed diode with a shorter reverse recovery time in conjunction with an inductor to manage the reverse recovery current.
Implementation Method 1
a second rectifying element that has a reverse recovery time that is shorter than a reverse recovery time of the first rectifying element, the second rectifying element being connected in parallel with the second inductor that supplies current to the load
Implementation Method 2
a second inductor that is provided in the conduction path so as to be connected in series with the first rectifying element
Data Source
AI summary
In a switching power supply apparatus, a switching element is turned on/off to intermittently conduct current input via an inductor. Current input during a period in which the switching element is turned off is supplied to an electrolytic capacitor via a conduction path. A rectifier diode is provided in the conduction path to face toward the electrolytic capacitor. An inductor is provided in the conduction path to be connected in series with the rectifier diode. A high speed diode has a reverse recovery time shorter than the reverse recovery time of the rectifier diode, and is connected in parallel with the inductor to face toward the electrolytic capacitor.