Sensorless Current Sharing in Multi-Stage Power Converters
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Solution Overview
Problem
Existing multi-stage power converters require numerous sensors to monitor and regulate electrical power, leading to increased complexity and cost, particularly in applications like vehicle charging systems.
Innovation Solution
A sensorless control method is implemented using outer and inner control loops, where the AC/DC stage regulates the final output and the DC/DC stage controls the intermediary bus, eliminating the need for DC/DC output current sensors, and utilizing PI controllers to manage current and voltage ratios independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are used to monitor and regulate electrical power in multi-stage power converters, then measurement precision and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The system uses self-service by having the AC/DC stage monitor its own output current and use this information to control the DC/DC stage current, eliminating the need for separate sensors on the DC/DC output. The control loop uses readily available measurements from the AC/DC stage to achieve precise regulation without additional sensing components.
Solution Approach 2:
The AC/DC stage serves multiple functions: it not only performs AC to DC conversion but also acts as the sensing and control reference for the entire multi-stage system. By making the AC/DC stage universal, the patent eliminates the need for separate sensing infrastructure on the DC/DC stage, reducing overall device complexity while maintaining measurement precision.
2Reliability
If multiple sensors are installed to monitor each stage output, then reliability is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent extracts the sensing function from the DC/DC stage and relocates it to the AC/DC stage. By taking out the redundant sensing requirement from the DC/DC output, the system maintains reliability through the control loop while reducing the number of sensors needed, thereby lowering manufacturing cost and simplifying production.
Solution Approach 2:
The monitoring and control functions are merged into a unified system where the AC/DC stage's output current measurement serves dual purposes: regulating its own output and controlling the DC/DC stage output. This merging eliminates redundant sensors and simplifies the overall system architecture, reducing manufacturing complexity and cost while maintaining reliable power regulation.
3Measurement precision
If DC/DC output current sensors are installed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The AC/DC stage output current measurement acts as an intermediary that indirectly provides the control information needed for DC/DC stage regulation. Instead of directly sensing DC/DC output current, the system uses the AC/DC stage measurement as a mediator, applying gain values to achieve precise DC/DC current control without requiring direct sensors on the DC/DC output.
Solution Approach 2:
The patent replaces the physical sensor mechanism on the DC/DC stage with a control-theoretic approach using gain values and control loops. This substitution eliminates the need for mechanical or electronic sensing components on the DC/DC output while maintaining measurement precision through mathematical relationships and feedback control.
4Stability of the object's composition
If fixed power distribution is used in parallel power converters, then stability is improved, but adaptability decreases
Solution Approach 1:
The patent implements dynamic power distribution by allowing the controller to adjust gain values in real-time based on system conditions and performance requirements. This dynamic approach enables the system to adapt power distribution among parallel converters while maintaining stability through closed-loop control, combining both stability and adaptability in the power management system.
Solution Approach 2:
The system achieves adaptability by changing control parameters (gain values) rather than fixing the power distribution architecture. By modifying these parameters, the system can dynamically adjust power distribution among parallel converters to optimize performance, handle varying loads, and adapt to changing conditions while maintaining stable operation through controlled parameter transitions.
Data Source
AI summary
Disclosed are embodiments for sensorless multi-stage power converters. The multi-stage power converters include a first stage that regulates a current of an input to the first stage and a second stage that regulates a voltage obtained from the first stage.