DC-Link Voltage Stabilization via Iterative Control
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Solution Overview
Problem
In power electronics systems, maintaining a stable DC-link voltage is challenging due to measurement errors, unknown dynamics, and communication delays, which require large and costly capacitors for buffering, especially in mobile applications like hybrid electric vehicles.
Innovation Solution
A power electronics system with a supervisory controller and a high-bandwidth bus voltage controller that iteratively updates adjustment signals to voltage converters, reducing the need for large capacitors by quickly adjusting DC-link voltage to match desired levels, thereby minimizing capacitance, size, and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If large-capacitance DC-link capacitors are used to buffer energy and filter voltage ripple, then DC-link voltage stability is improved, but device size and weight increase significantly
Solution Approach 1:
The patent replaces the traditional mechanical/electrical buffering system (large capacitors) with a control system that uses iterative calculation and high-frequency switching of voltage converters to achieve voltage stabilization, substituting physical energy storage with active control
Solution Approach 2:
The patent changes the control parameters by implementing iterative calculation of adjustment signals with higher update frequencies, allowing the system to respond dynamically to voltage variations without requiring large energy buffering capacity
2Stability of the object's composition
If large-capacitance DC-link capacitors are used to buffer energy, then DC-link voltage stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive large-capacitance components with a control strategy that uses computational algorithms and standard-voltage converters, significantly reducing bill of materials cost while maintaining voltage stability
3Weight of stationary object
If high-frequency iterative adjustment signals are used to stabilize DC-link voltage, then capacitor size is reduced, but control system complexity increases
Solution Approach 1:
The control system measures the actual DC-link voltage, compares it with the desired voltage, and automatically generates correction signals through iterative calculation, making the system self-regulating without external intervention
Solution Approach 2:
The patent implements a feedback mechanism where the measured DC-link voltage is continuously compared with the desired voltage, and the difference (error) is used to generate adjustment signals that are fed back to the voltage converter to correct the voltage deviation
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 allows for efficient power conversion with reduced capacitor size and weight, enhancing operational efficiency and cost-effectiveness in mobile applications by rapidly stabilizing DC-link voltage.
Implementation Method 1
The first voltage converter is configured to convert a first DC voltage from the first energy storage device into a second DC voltage based on a command signal and based on a first adjustment signal
Implementation Method 2
the DC-link is equipped with one or more capacitive devices (e.g., a battery or ultracapacitor) that provides substantial capacitance to filter the voltage ripple resulting from current ripple and to buffer energy
Data Source
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AI summary
An apparatus includes a DC-link (26), a voltage converter (14), a bus voltage controller (36), and a supervisory controller (12). The voltage converter (14) is configured to convert a first DC voltage into a second DC voltage based on a command signal and based on an adjustment signal and to supply the second DC voltage to the DC-link (26). The bus voltage controller (36) is configured to iterate calculation of the adjustment signal to communicate each iterated calculation of the adjustment signal to the voltage converter (14). The supervisory controller (12) is configured to iterate calculation of the command signal and to communicate each iterated calculation of the command signal to the voltage converter (14) and to the bus voltage controller (36). A frequency of the bus voltage controller (36) to communicate each iterated calculation of the adjustment signal is higher than a frequency of the supervisory controller (12) to communicate each iterated calculation of the command signal.