Power Conversion Device Soft Switching Control
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Solution Overview
Problem
Existing power conversion devices, such as dual active bridge (DAB) type DC/DC converters, face challenges in achieving zero voltage switching operation at light load conditions or when input and output voltages are significantly different, leading to increased conduction loss and requiring additional components or complex control methods.
Innovation Solution
A power conversion device with a primary-side and secondary-side bridge circuit, utilizing snubber capacitors and inductance elements to achieve zero voltage switching through resonance, and a control device that calculates and adjusts the duty cycles and phase shift to minimize losses without increasing the number of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the DAB-type DC/DC converter uses resonance between leakage inductance and snubber capacitor for soft switching, then switching loss is reduced, but under light load conditions or when input and output voltages are greatly different, soft switching cannot be achieved and switching loss increases
Solution Approach 1:
The patent dynamically adjusts the duty ratios of primary and secondary full-bridge inverters and the phase difference between them based on operating conditions. This dynamic control enables the system to maintain soft switching operation across a wider range of load conditions and voltage differences without requiring additional hardware components.
Solution Approach 2:
The patent changes control parameters (duty ratios and phase difference) to optimize the resonance condition between leakage inductance and snubber capacitor. By adjusting these parameters, the system maintains zero voltage switching operation under varying load conditions and voltage differences, expanding the soft switching operation region.
2Adaptability or versatility
If auxiliary circuits are added to expand soft switching operation region, then soft switching can be maintained under more conditions, but the number of components increases
Solution Approach 1:
The patent uses the existing leakage inductance and snubber capacitor components of the DAB converter to create the resonance necessary for soft switching. By utilizing components already present in the circuit for dual purposes (snubber function and resonance), the system expands its soft switching operation region without adding auxiliary circuits or increasing component count.
Solution Approach 2:
The patent makes the existing leakage inductance and snubber capacitor serve multiple functions: the snubber capacitor provides both voltage clamping protection and resonance for soft switching, while the leakage inductance serves both transformer isolation and resonance inductance. This multi-functionality eliminates the need for additional auxiliary components.
3Adaptability or versatility
If inverter duties and phase difference are adjusted to expand soft switching region, then soft switching operation region is expanded, but peak current might increase leading to increased conduction loss
Solution Approach 1:
The patent employs control strategies that monitor operating conditions and adjust inverter duties and phase difference accordingly. This feedback control enables the system to expand the soft switching operation region while maintaining optimal current levels, preventing excessive peak current and associated conduction losses.
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 enables zero voltage switching operation, minimizing switching and conduction losses without adding components, and expands the operational region for soft switching, thereby improving efficiency and reducing losses.
Implementation Method 1
a power conversion device that performs power conversion between DC voltages, and in particular, relates to technology for reducing generated loss therein... uses a resonance phenomenon between a leakage inductance of the transformer and a snubber capacitor connected in parallel to a switching element
Data Source
AI summary
Provided is a power conversion device including a power converter for performing power conversion between primary-side DC voltage and secondary-side DC voltage, and a control device for controlling the power converter in accordance with a command value, wherein the control device generates a primary-side duty for a primary-side bridge circuit, a secondary-side duty for a secondary-side bridge circuit, and a phase shift amount between the primary-side bridge circuit and the secondary-side bridge circuit, on the basis of a solution of an optimization problem for minimizing a peak absolute value of current flowing through the transformer, under a constraint condition that zero voltage switching operation is achieved, at an operation point based on the command value, thus achieving zero voltage switching operation and suppressing increase in conduction loss, without increase in the number of components.