Piezoactuator Current Control for Linear Charge and EMC
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Solution Overview
Problem
In piezo systems for internal combustion engines, existing methods for controlling piezo actuators often lead to non-linear charge application and electromagnetic compatibility issues due to residual energy in transfer inductances, particularly in accumulator injection and gasoline direct injection systems.
Innovation Solution
A method and arrangement that monitor the current through piezo actuators and control current pulses based on a defined time window, ensuring linear charge application and efficient energy use by switching off the current pulse when it falls below a target current within the window, thereby improving electromagnetic compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the cylinder selection is switched off exactly after the end of the charging or discharging time in BDE piezo systems, then the control timing is precise and simple, but the electromagnetic compatibility requirements are not met due to residual energy in the transfer inductance
Solution Approach 1:
The patent introduces a feedback mechanism that monitors the current through the piezo actuator and uses this information to determine when to switch off the cylinder selection. The control unit continuously measures the current and compares it against threshold values to decide the optimal switch-off moment, ensuring both timing precision and electromagnetic compatibility.
Solution Approach 2:
The patent implements dynamic control by adjusting the switch-off timing based on real-time current conditions. Instead of using a fixed switch-off time, the system dynamically determines the switch-off moment by evaluating whether the current has fallen below specific thresholds within defined time windows, adapting to varying operating conditions.
2Ease of operation
If a linear charge is applied to the piezo actuator by switching off the cylinder immediately after the charging time, then the charge application is linear and simple to control, but residual energy remains in the transfer inductance causing EMC issues
Solution Approach 1:
The patent replaces the traditional time-based mechanical switching approach with an electronic feedback-based control system. Instead of relying solely on predetermined timing circuits, the system uses electronic current sensing and comparison logic to determine switch-off timing, substituting mechanical timing mechanisms with electronic intelligence.
3Object-affected harmful factors
If the current pulse is extended to ensure complete energy discharge, then electromagnetic compatibility is improved, but the charging time increases and system productivity decreases
Solution Approach 1:
The patent changes the control parameters by introducing current threshold values and time window parameters that define the switch-off condition. Instead of extending the current pulse duration uniformly, the system adjusts the switch-off timing based on whether the current falls below thresholds within specific time windows, optimizing both EMC and charging speed.
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 ensures a linear charge application to piezo actuators without negatively impacting electromagnetic compatibility, allowing for more precise control of charging and discharging phases, and optimizing the use of energy in piezo systems.
Implementation Method 1
a piezoelectric actuator (130), which is assigned to a cylinder (372; 870) and is designed to drive a valve element (432; 433) of this cylinder
Data Source
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AI summary
The invention relates to a method for operating a final stage for a piezoactuator, wherein during an operating phase, if a current (80) for the piezoactuator falls below a target current (82), it is checked whether a point in time for the falling of the current below the target current lies outside or inside a time frame (90), wherein a subsequent current pulse is controlled by means of the target current (82) if the point in time (92, 93, 94) is outside the time frame (90), and wherein the subsequent current pulse is controlled by means of a switch-on time if the point in time is inside the time frame (90). The invention further relates to an arrangement for operating a final stage for a piezoactuator, to a computer program, and to a computer program product.