Resonant Converter Two-Stage Voltage Loop for Thermal and Ripple Control
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Solution Overview
Problem
Existing battery charger systems face challenges in meeting increased efficiency requirements and higher power density needed for automotive onboard chargers, particularly in managing thermal and ripple current issues.
Innovation Solution
The system employs a two-stage voltage loop configuration, including an AC-DC converter and a DC-DC converter, with controllers that determine current demand, compare it to thresholds, and generate a voltage setpoint for the bulk capacitor to limit output current ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a two-stage layout is used to achieve high power density with less weight and space, then power density is improved, but thermal and ripple current issues worsen
Solution Approach 1:
The patent implements a dynamic voltage setpoint adjustment mechanism that adapts the bulk capacitor voltage based on real-time operating conditions including current demand and temperature. The controller dynamically modifies the voltage setpoint to optimize thermal performance while maintaining power density requirements, resolving the contradiction between high power density and thermal management
Solution Approach 2:
The system changes the voltage setpoint parameter of the bulk capacitor based on operating conditions. By adjusting this key parameter dynamically, the system optimizes thermal performance and reduces ripple current effects while maintaining the high power density achieved through the two-stage layout
2Power
If a two-stage layout is used to achieve high power density with less weight and space, then power density is improved, but ripple current issues worsen
Solution Approach 1:
The controller dynamically adjusts the voltage setpoint based on real-time current demand and operating conditions. This dynamic adjustment smooths ripple current by adapting the bulk capacitor voltage to match instantaneous load requirements, reducing the harmful ripple current effects while maintaining high power density
Solution Approach 2:
The system employs feedback control where the controller continuously monitors operating conditions and adjusts the voltage setpoint accordingly. This feedback mechanism reduces ripple current by compensating for variations in load demand and maintaining optimal voltage levels throughout the two-stage conversion process
3Use of energy by moving object
If conventional control methods are used, then device complexity is low, but efficiency requirements are not met
Solution Approach 1:
The patent implements a dynamic control strategy that adjusts the voltage setpoint based on real-time operating conditions. This dynamic approach improves efficiency by optimizing power conversion at different operating points, while the control complexity is managed through a systematic method that compares current demand to thresholds and applies predefined adjustment rules
4Object-generated harmful factors
If the voltage setpoint is adjusted to limit output current ripple, then ripple current is reduced, but control complexity increases
Solution Approach 1:
The control method segments the current demand range into different thresholds and applies specific control strategies for each segment. By dividing the control space into manageable segments with predefined adjustment rules, the system reduces output current ripple through targeted voltage setpoint adjustments while keeping control complexity manageable through modular decision logic
Data Source
AI summary
A system includes: an alternating current (AC) to direct current (DC) converter (AC-DC converter), the AC-DC converter including a bulk capacitor; a DC-DC converter connectable to the AC-DC converter; and one or more controllers configured to control the system by performing operations, the operations including: determining a current demand of a load, the load being connectable to the DC-DC converter, for a charging cycle of the load; performing a first comparison of the current demand to one or more current demand thresholds; and generating a voltage setpoint for the bulk capacitor based on the first comparison, wherein the generation of the voltage setpoint limits output current ripple of the DC-DC converter for the charging cycle.