Parallel LLC DC/DC Charger With Autonomous Current Sharing
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Solution Overview
Problem
Existing charging systems require separate chargers for each battery type of different voltage levels, leading to inefficiencies in space and cost, and existing LLC resonant converters are difficult to control for wide output voltage.
Innovation Solution
A multi-parallel control DC/DC converter using autonomous current sharing control, equipped with a converter circuit unit and mounting unit, that can automatically recognize and charge batteries of various voltage levels, allowing multiple chargers to be connected in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate chargers are used for each battery type of different voltage levels, then charging capability for specific battery type is ensured, but space and cost efficiency deteriorate
Solution Approach 1:
The charger is designed with a universal charging platform that can charge multiple types of batteries with different voltage levels (e.g., 18V, 36V, 54V) using a single device. The system includes voltage detection circuitry and adjustable charging parameters that adapt to different battery types, eliminating the need for separate dedicated chargers for each voltage level while maintaining reliable charging capability across all battery types.
2Loss of energy
If LLC resonant converter is used, then charging efficiency is improved, but output voltage control range deteriorates
Solution Approach 1:
The system employs dynamic control of the LLC resonant converter by adjusting the switching frequency across a wide range. The controller dynamically modifies the operating frequency to adapt to different output voltage requirements and load conditions, enabling the resonant converter to maintain high efficiency while achieving a broad output voltage control range suitable for multiple battery voltage levels.
Solution Approach 2:
The system changes key operating parameters of the LLC resonant converter, particularly the switching frequency, to adapt to different charging requirements. By varying the frequency within an optimized range and adjusting duty cycle, the system maintains resonant operation for high efficiency while achieving wide voltage output control to accommodate different battery types.
3Productivity
If multiple chargers are connected in parallel, then total charging capacity is increased, but current sharing control complexity increases
Solution Approach 1:
The parallel charger system implements autonomous current sharing control where each charger unit independently regulates its own output current based on local sensing and simple control logic. The system uses current sampling resistors and control circuits that automatically balance the current distribution among parallel units without requiring complex centralized control or communication between units, thereby increasing charging capacity while minimizing control complexity.
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
Enables efficient charging of batteries with different voltage levels using a single standard model, increasing charging capacity and flexibility, while reducing the need for multiple chargers.
Implementation Method 1
a converter circuit unit (10) designed to charge batteries of different voltage levels by controlling an output voltage using an LLC resonant DC/DC converter
Implementation Method 2
a burst mode PID controller (11) configured to maintain a constant voltage under no-load conditions by applying PWM (Pulse Width Modulation)
Data Source
AI summary
The present invention provides a multi-parallel control DC/DC converter using autonomous current sharing control, which comprises a converter circuit unit designed to charge batteries of different voltage levels and a mounting unit for parallel connection.