Flywheel Energy Storage Control for Servo Press Power Peaks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Intermediate circuit converters face inefficiencies in managing power peaks for dynamic loads like servo press drives, where power requirements vary significantly due to acceleration, braking, and external loading, making mechanical energy storage via rotating flywheel mass more economical than capacitor storage for large payloads.
Innovation Solution
A control device that regulates the feed and buffer converters by determining target currents and torques based on actual voltage and speed, using PI and P regulators to stabilize power delivery, and optionally employing a pre-control circuit with high-pass filtering to adjust torque setpoints, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If capacitor energy storage is used to cover power peaks, then electrical energy can be stored in the intermediate circuit, but for large payloads capacitor energy storage becomes uneconomical
Solution Approach 1:
The patent changes the energy storage parameter from electrical (capacitor) to mechanical (flywheel) based on the payload size and power peak requirements. For large payloads with high power peaks, mechanical energy storage via flywheel becomes more economical than electrical storage via capacitor, as stated in the background section.
Solution Approach 2:
The patent replaces the electrical energy storage system (capacitor) with a mechanical energy storage system (flywheel with rotating mass) for large payload applications. This substitution is driven by economic considerations for large presses requiring 800 tons and more pressing force.
2Reliability
If the intermediate circuit converter is oriented to average power, then the system can handle sustained loads, but power peaks cannot be covered without excessive energy storage
Solution Approach 1:
The control of energy storage is segmented into two independent regulators: a voltage regulator that maintains stable DC link voltage for reliable operation, and a power regulator that manages power peak coverage. This segmentation allows the system to handle both average power and power peaks without requiring excessive energy storage capacity.
Solution Approach 2:
The patent implements dynamic control where the flywheel speed and energy storage capacity are actively regulated to match instantaneous power requirements. The dual-regulator system dynamically adjusts the energy storage usage based on whether the system needs to maintain voltage stability or cover power peaks, optimizing the use of energy storage resources.
3Adaptability or versatility
If a dual regulator system is implemented, then both voltage stability and power peak coverage are achieved, but control complexity increases
Solution Approach 1:
The control system is segmented into two independent regulators with distinct functions: the voltage regulator focuses on maintaining DC link voltage stability, while the power regulator focuses on covering power peaks by controlling flywheel power. This functional segmentation makes the complex dual-regulator system manageable and allows each regulator to be optimized for its specific task.
Solution Approach 2:
The flywheel energy storage system serves multiple functions through the dual regulator approach: it can maintain voltage stability during normal operation and can also provide power peak coverage when needed. The same physical system (flywheel + converters) performs both voltage regulation and power management functions, reducing the need for separate systems.
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 enables efficient and reliable operation by stabilizing power delivery and reducing the need for excessive energy storage, maintaining average power consumption constant despite varying instantaneous demands.
Implementation Method 1
mechanical via a rotating flywheel mass connected to the intermediate circuit
Implementation Method 2
a rotating centrifugal mass is coupled to the DC voltage intermediate circuit for bidirectional energy exchange
Implementation Method 3
the intermediate circuit converter has a DC voltage intermediate circuit, in which an intermediate circuit capacitor is arranged
Data Source
AI summary
A first voltage regulator (13) determines reference voltage and actual voltage (U) of intermediate circuit capacitor and desired current for supply inverter (3), so that supply inverter is controlled accordingly. A speed controller (15) determines reference torque component for flywheel (9) based on set speed and an actual speed of inertial mass. A voltage regulator (14) determines second reference torque component for flywheel based on nominal voltage and actual voltage. The reference torque components are added to desired torque and the buffer converter (8) is controlled accordingly. An independent claim is included for indirect converter.