Single-Stage On-Board Charger With Integrated Pulsating Buffer
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Solution Overview
Problem
Existing on-board chargers (OBCs) for electric vehicles face inefficiencies due to bulky and costly energy storage elements, such as electrolytic capacitors, which reduce power density and increase the maximum operating temperature and estimated lifetime, while also requiring multiple stages of power factor correction and DC/DC conversion for each rail, leading to poor power density and reliability.
Innovation Solution
A single-stage OBC with an integrated pulsating buffer (PB) converter that eliminates current ripple and uses a transformer with dual active bridges and a controller to manage power transfer, reducing the need for bulky capacitors and inductors, and enabling bi-directional power flow by replacing diodes with active switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrolytic capacitors are used for energy storage in OBC, then power factor correction and DC/DC conversion can be achieved, but power density is reduced and maximum operating temperature increases
Solution Approach 1:
The patent changes the energy storage mechanism from electrolytic capacitors to a pulsating buffer converter with active switches and transformer-based energy transfer. This parameter change eliminates the temperature limitations of electrolytic capacitors while maintaining power factor correction and DC/DC conversion functions through controlled switching and magnetic energy storage.
Solution Approach 2:
The patent extracts and eliminates the electrolytic capacitor from the circuit by replacing it with a pulsating buffer converter topology. The buffer converter uses active switches and inductors to perform the energy storage function without relying on electrolytic capacitors, thereby removing the temperature constraint while preserving the required power conversion functions.
2Reliability
If electrolytic capacitors are used for energy storage in OBC, then power factor correction and DC/DC conversion can be achieved, but power density is reduced
Solution Approach 1:
The patent changes the energy storage approach from bulky electrolytic capacitors to a compact pulsating buffer converter using active switches and magnetic components. This enables higher power density by reducing the volume of energy storage elements while maintaining the necessary power conversion and factor correction functions through controlled switching operations.
Solution Approach 2:
The patent removes the bulky electrolytic capacitor from the system and replaces it with a pulsating buffer converter topology that uses smaller magnetic components and active switches. This extraction of the problematic component directly increases power density while preserving the essential power factor correction and DC/DC conversion capabilities.
3Ease of operation
If multiple stages of power factor correction and DC/DC conversion are used, then charging function is achieved, but device complexity increases
Solution Approach 1:
The patent merges the power factor correction stage and the DC/DC conversion stage into a single integrated pulsating buffer converter topology. The active switches and transformer perform both functions simultaneously, eliminating the need for separate correction and conversion stages, thereby reducing device complexity while maintaining full charging functionality.
Solution Approach 2:
The pulsating buffer converter is designed as a multi-functional unit that performs both power factor correction and DC/DC conversion within a single stage. The active switches and magnetic components serve multiple purposes: correcting power factor, transferring energy, and regulating output voltage, thus simplifying the overall charger structure while achieving complete charging capability.
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 solution enhances power density, reduces component costs, and improves the maximum operating temperature and reliability by eliminating the need for bulky capacitors and inductors, while enabling efficient bi-directional power flow.
Implementation Method 1
The at least one transformer includes one or more primary windings and one or more secondary windings
Implementation Method 2
The first active bridge includes a first plurality of switching devices being positioned with the one or more primary windings on a primary side of the charger to generate a first voltage signal
Data Source
AI summary
In at least one embodiment, a vehicle battery charger is provided. The charger includes at least one transformer, a first active bridge, a second active bridge, and at least one controller. The first active bridge includes a first plurality of switching devices being positioned with the primary. The second active bridge includes a second plurality of switching devices being positioned with the secondary to generate. The controller is configured to activate the first plurality of switching devices based on a primary control signal and to activate the second plurality of switching devices based on a secondary control signal. The controller is configured to generate the secondary control signal in accordance to a first control variable. The controller is further configured to generate a second control variable that corresponds to a phase shift between the primary control signal and the secondary control signal.