Series Resonant Converter Current Control Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Series resonant converters face challenges with control precision due to their operation as voltage-to-voltage converters, leading to overshooting and the need for large storage capacitors with limited lifespan, which are inefficient and prone to fluctuations.
Innovation Solution
A method for controlling series resonant converters by calculating an average output current using a transfer function that considers intermediate circuit voltage, output voltage, switching period, and duty cycle, allowing for more robust and precise control, enabling the use of smaller capacitors and optimizing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large storage capacitors are used to buffer and average disturbances, then control quality is improved, but installation space increases and capacitor lifespan is limited
Solution Approach 1:
The patent changes the control parameter from voltage-based control to current-based control. By controlling the average output current instead of output voltage, the system achieves better control quality without requiring large storage capacitors. The transfer function relates switching frequency and duty cycle to average output current, enabling precise control with smaller capacitive components.
Solution Approach 2:
The patent replaces the mechanical/electrical buffering function performed by large capacitors with a control algorithm. The microcontroller calculates the required switching frequency and duty cycle using the transfer function to achieve the desired average output current, substituting the need for large energy-storing capacitors with computational control.
2Device complexity
If voltage-to-voltage control is used, then converter simplicity is maintained, but control precision deteriorates due to overshoot and fluctuations
Solution Approach 1:
The patent changes the fundamental control parameter from voltage to current. Instead of controlling output voltage directly, the system controls the average output current through a transfer function that relates switching frequency and duty cycle to current. This parameter change eliminates overshoot and improves control precision while maintaining relatively simple converter hardware.
3Adaptability or versatility
If switching frequency is adjusted for control, then adaptability is improved, but control precision deteriorates due to voltage fluctuations
Solution Approach 1:
The patent implements a feedback mechanism where the microcontroller measures the actual average output current and adjusts the switching frequency and duty cycle accordingly. The transfer function provides the relationship between control parameters and output current, enabling closed-loop control that maintains precision while adapting to load changes and disturbances.
Solution Approach 2:
The patent changes from voltage-based control to current-based control parameters. By using average output current as the control variable instead of voltage, the system achieves both adaptability to load changes and precision without the overshoot and fluctuations inherent in voltage-to-voltage control methods.
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 more accurate and stable control of series resonant converters, reducing the need for large capacitors, improving lifespan, and optimizing power efficiency by operating as voltage-to-current converters, thus addressing the limitations of prior art.
Implementation Method 1
The series resonant converter with galvanic isolation comprises a half-bridge or a full bridge that drives the series resonant circuit with a unipolar or bipolar square wave voltage
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2a~2d
AI summary
The invention relates to a method for controlling a series resonant converter (110), wherein the series resonant converter (110) has a primary circuit (112) and a secondary circuit (114), wherein the primary circuit (112) or the secondary circuit (114) has a series resonant circuit (118), wherein the series resonant circuit (118) comprises at least one capacitance C 1 and at least one inductance L i , wherein an intermediate circuit voltage U dc is applied to the primary circuit (112), and wherein the secondary circuit (114) provides an average output current Ī out , wherein the series resonant converter (110) is controlled by setting an averaged value for the output current Ī out by means of a transfer function, wherein the transfer function is a function of the intermediate circuit voltage U dc , the output voltage U Cout , the inductance L i , a switching period t p and a duty factor D, wherein at least the switching period t p and/or the duty factor D is/are set. The invention also relates to a computer program which is configured to at least partially carry out the method.