Bidirectional Resonant Power Supply With Single-Stage AC-DC Conversion
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Solution Overview
Problem
Existing bidirectional power supplies require two separate stages for AC-DC and DC-AC conversion, leading to challenges in designing transformers and achieving high efficiency, and are not suitable for bidirectional operation.
Innovation Solution
A single-stage bidirectional power supply that employs an alternating combination of variable frequency and variable time delay control for primary and secondary switches, allowing both current shaping and output voltage regulation, using a bidirectional resonant converter with primary and secondary switches on a transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage approach with PFC converter and DC-DC converter is used, then power factor correction and voltage conversion are achieved, but device complexity and weight increase
Solution Approach 1:
The patent combines the PFC converter and DC-DC converter into a single bidirectional resonant converter stage. The resonant converter performs both power factor correction and voltage conversion simultaneously by using resonant tanks on both primary and secondary sides, eliminating the need for separate PFC and DC-DC stages while maintaining bidirectional power flow capability.
Solution Approach 2:
The bidirectional resonant converter is designed to perform multiple functions: power factor correction, voltage conversion, and bidirectional power flow. The same circuit topology and switches handle both AC-DC and DC-AC conversion, making the device universal and eliminating the need for separate dedicated circuits for each function.
2Adaptability or versatility
If switching frequency is varied widely to handle different voltages, then adaptability is improved, but efficiency decreases due to increased losses
Solution Approach 1:
The patent uses resonant frequency operation where the switching frequency is tied to the resonant frequency of the LC tanks rather than being varied widely. By operating at or near the resonant frequency, the converter achieves soft switching conditions that minimize switching losses while still handling a wide voltage range through the resonant impedance transformation ratio.
Solution Approach 2:
The patent exploits resonant oscillation in the LC tanks to transfer power. The resonant tanks naturally oscillate at a specific frequency, and by synchronizing the switching with this resonant frequency, the converter achieves efficient energy transfer with minimal losses while adapting to different voltage conditions through the resonant coupling.
3Adaptability or versatility
If bidirectional operation is implemented in traditional two-stage converters, then power flow flexibility is improved, but transformer design complexity and cost increase
Solution Approach 1:
The patent uses a single resonant converter stage with bidirectional switches that can operate in both forward and reverse directions. The primary and secondary resonant tanks are designed to be symmetrical, allowing the converter to naturally handle bidirectional power flow without requiring complex bidirectional transformer designs or additional circuitry.
Solution Approach 2:
The patent enables bidirectional operation by allowing the converter to operate in reverse mode where the roles of primary and secondary sides are inverted. The same resonant tanks and switches that convert AC to DC can also convert DC to AC by reversing the switching sequence, eliminating the need for separate bidirectional transformer windings or complex magnetic designs.
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 reduces the number of components, saves weight and cost, and ensures efficient operation across a wide range of input and output voltages without varying switching frequencies widely, making it suitable for bidirectional power flow.
Implementation Method 1
a transformer that passes the AC signal by electromagnetic induction to a secondary side of the transformer
Implementation Method 2
bidirectional resonant converter includes a primary port with primary-side switches and a secondary side port with secondary-side switches
Data Source
AI summary
A bidirectional power supply includes an alternating current (AC) port as a source in a first mode and as a load in a second mode and a line-frequency rectifier/inverter to function as a rectifier in the first mode and a set of switches to function as an inverter in the second mode. A bidirectional resonant converter is coupled to a direct current (DC) port with primary-side switches and secondary-side switches respectively arranged on a primary and secondary side of a transformer. A controller controls the primary-side switches and the secondary-side switches by controlling switching frequency based on a determined value while setting time delay between control of the primary-side and the secondary-side switches to be a predefined time delay or by controlling the time delay between control of the primary-side and the secondary-side switches based on a determined value while setting the switching frequency to be a predefined switching frequency.