ARCPI Boosting Time Control With Saturable Inductor Compensation
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Solution Overview
Problem
The non-linearity of saturable inductors in PWM ARCPIs impairs the accuracy of current controllability in auxiliary semiconductor devices, leading to inaccuracies in boosting current levels, which affects zero-voltage switching and switching losses.
Innovation Solution
A method that calculates the boosting time in the auxiliary switch path using a processor, considering both theoretical resonance inductance and a look-up table, to correct the boosting current levels, especially by extending the boosting time when the saturable inductor reaches saturation, and using non-linear approximations based on curve fitting equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a saturable inductor is used in the auxiliary switch path to mitigate excessive transient voltage, then the voltage protection is improved, but the accuracy of current controllability deteriorates due to non-linearity
Solution Approach 1:
The patent implements a feedback mechanism where the controller measures the actual current through the auxiliary semiconductor device and compares it with the target current. Based on this comparison, the controller adjusts the boosting time to compensate for the non-linearity of the saturable inductor, thereby maintaining accurate current controllability while using the saturable inductor for voltage protection.
Solution Approach 2:
The patent changes the parameter of boosting time dynamically based on the operating conditions and the non-linear characteristics of the saturable inductor. By adjusting the boosting time parameter, the system compensates for the non-linearity effects and maintains precise current control despite the presence of the saturable inductor.
2Measurement precision
If the boosting time is extended to account for saturable inductor saturation, then the current control accuracy is improved, but the switching timing precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between boosting current and required boosting time in a look-up table, obtained through circuit simulation. During operation, the controller directly queries this pre-computed table based on the desired current level, eliminating the need for real-time complex calculations and ensuring both accurate current control and precise switching timing.
Solution Approach 2:
The patent makes the boosting time dynamic by selecting different time values from the look-up table based on the required boosting current level. This dynamic adjustment allows the system to optimize both current control accuracy and switching timing precision for different operating conditions without compromising either parameter.
3Measurement precision
If a look-up table with non-linear approximation is used to determine boosting time, then the current control accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent performs the complex non-linear calculations in advance during circuit simulation to generate the look-up table. This pre-computation approach transfers the computational complexity from the real-time control system to the design phase, allowing the actual controller to simply query pre-stored values, thereby maintaining high current control accuracy while minimizing real-time device complexity.
4Ease of operation
If the boosting time is calculated based on theoretical resonance inductance only, then the calculation simplicity is improved, but the current control accuracy deteriorates due to non-linearity
Solution Approach 1:
The patent performs preliminary simulation to obtain the non-linear relationship between boosting current and boosting time, storing this relationship in a look-up table. This approach captures the complex non-linear behavior without requiring complex real-time calculations, thus maintaining both calculation simplicity and current control accuracy.
Solution Approach 2:
The patent creates a simplified model (look-up table) that copies the essential non-linear characteristics of the saturable inductor's behavior. This copied model allows the controller to achieve accurate current control by simple table lookup operations rather than complex theoretical calculations, balancing simplicity and accuracy.
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 provides more accurate boosting current levels, improving the accuracy of current control and maintaining zero-voltage switching while minimizing the impact of saturable inductor non-linearity, thus enhancing the overall efficiency of the PWM ARCPI.
Implementation Method 1
a resonant inductor Lr with at least one saturable inductor Lsat in the auxiliary switch path
Implementation Method 2
The method includes: calculating, by a processor of the auxiliary device, a first boosting time in the auxiliary switch path based on a theoretical resonance inductance and a voltage that are applied to the resonant inductor
Data Source
Figure 1(a)
Figure 1(b)
Figure 2(a)
AI summary
A method for an auxiliary device of an auxiliary resonant commutated pole inverter (ARCPI) to determine a boosting time of the ARCPI is provided. The auxiliary device includes an auxiliary switch path that uses a resonant inductor with at least one saturable inductor. The method includes: calculating, by a processor of the auxiliary device, a first boosting time in the auxiliary switch path based on a theoretical resonance inductance and a voltage that are applied to the resonant inductor; determining, by the processor, a second boosting time in the auxiliary switch path based on a look-up table; and determining, by the processor, the boosting time in the auxiliary switch path based on the first boosting time and the second boosting time. The method further includes controlling, by the processor, boosting current of the ARCPI based on the boosting time in the auxiliary switch path.