Piezo Actuator Overcurrent Detection via Charging Coil
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Solution Overview
Problem
Existing methods for identifying overcurrents during piezo actuator charging are inadequate in preventing internal shorts and overheating, as they often disconnect too late, leading to component damage, and face challenges with new PowerMOS technologies that prioritize low switching losses.
Innovation Solution
A method that periodically connects and disconnects the piezo actuator to an energy source via a charging coil, identifying overcurrents by specific timing conditions, such as disconnection at minimum switched-on time with maximum current reached or reconnection at maximum switched-off time without minimum current, and uses a fault counter to enhance robustness and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If disconnection is delayed until maximum current is reached, then charging efficiency is improved, but component damage risk increases due to overheating and internal shorts
Solution Approach 1:
The patent applies preliminary action by monitoring multiple parameters (current, temperature, time) simultaneously and predicting potential overcurrent conditions before they occur. The system disconnects the piezo actuator proactively when abnormal patterns are detected, rather than waiting for maximum current to be reached or for damage to occur. This is achieved through a control unit that continuously evaluates charging parameters and triggers disconnection based on predictive criteria, preventing overheating and component damage while maintaining efficient charging operation.
2Loss of energy
If switching frequency is increased to reduce switching losses in PowerMOS technologies, then energy efficiency is improved, but overcurrent detection accuracy deteriorates
Solution Approach 1:
The patent introduces an intermediary evaluation mechanism that mediates between the high-frequency switching operation and accurate overcurrent detection. The control unit acts as an intermediary by continuously monitoring multiple parameters (current, temperature, time) and evaluating their combined patterns to detect abnormal charging states. This intermediary evaluation system enables accurate overcurrent detection despite high switching frequencies, as it analyzes the overall charging behavior rather than relying on single-point measurements that may be obscured by rapid switching.
3Productivity
If charging current is increased to reduce charging time, then productivity is improved, but reliability deteriorates due to higher risk of overcurrent and component failure
Solution Approach 1:
The patent implements feedback control by continuously monitoring charging parameters (current, temperature, time) and using this information to dynamically adjust the charging process. The control unit receives feedback from sensors measuring the actual charging state and compares it against safe operating limits. When abnormal conditions are detected, the system provides feedback by triggering disconnection, thereby preventing overcurrent and component failure. This feedback mechanism enables the system to maintain high charging currents for improved productivity while ensuring reliability through real-time monitoring and protective action.
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 method allows for earlier detection and prevention of overcurrents, reducing the risk of overheating and component damage by identifying abnormal current states and triggering disconnection before fault currents reach dangerous levels, thereby enhancing system robustness and reliability.
Implementation Method 1
charging is effected by periodically connecting and disconnecting the piezo actuator to and from an energy source via a charging coil
Implementation Method 2
charging a piezo actuator
Data Source
AI summary
A method for identifying an overcurrent when charging a piezo actuator, by periodically connecting and disconnecting the piezo actuator to and from an energy source via a charging coil. A connection is followed by a disconnection when the charging current has reached a prescribed maximum current value and a minimum switched-on time has elapsed, and a connection is effected again when either a prescribed minimum current value has been reached or a maximum switched-off time has elapsed. An overcurrent is identified when a disconnection is effected when the minimum switched-on time has elapsed and the charging current has previously reached or exceeded a prescribed maximum current value. An overcurrent is also identified when, after a disconnection on account of the prescribed maximum current value having been reached, a connection is effected again when the maximum switched-off time has elapsed without the minimum current value having been reached.