Adaptive Filter for Solenoid Valve Current Control
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Solution Overview
Problem
Motor vehicle control systems with digital closed loop systems for solenoid control valves face instability due to vehicle electrical system voltage ripple, leading to undesirable oscillations and slow response times during gear shifts, especially when setpoint current profiles exhibit sudden jumps.
Innovation Solution
Incorporating an adaptive correction filter in the feedback branch of the digital closed loop system with dynamically adjustable filter time based on the level dynamics of the setpoint value current, allowing for rapid correction during jumps while maintaining stability during minor changes, using a combination of slower and faster filters to address voltage ripple interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slow filter with a long filter time is used in the feedback branch to counteract voltage ripple interference, then the system becomes more robust with respect to voltage ripple, but the digital controller becomes more inert and slower in response to setpoint current jumps
Solution Approach 1:
The filter time of the correction filter is made dynamically adjustable based on the level change of the setpoint value current. When the setpoint current changes significantly (indicating a gear shift), the filter time is reduced to allow fast response. When the setpoint current is stable, the filter time is increased to filter out voltage ripple interference effectively.
Solution Approach 2:
The filter time parameter of the correction filter is changed according to the operating conditions. By monitoring the level change of the setpoint value current, the system adjusts the filter time parameter to optimize performance for either fast response or ripple suppression depending on the current operational state.
2Stability of the object's composition
If the filter time is increased to filter out voltage ripple interference, then the system becomes more stable, but the dynamic behavior in response to sudden setpoint current changes deteriorates
Solution Approach 1:
The correction filter transitions from a static filter time design to a dynamic one where the filter time adapts to the operational requirements. This allows the system to maintain stability during normal operation while achieving high dynamic response when setpoint changes occur.
Solution Approach 2:
The system periodically evaluates the level change of the setpoint value current and adjusts the filter time accordingly. This periodic adaptation ensures that the filter characteristics match the current operational phase, whether it be during gear shifts or steady-state operation.
Data Source
AI summary
In a motor vehicle control unit having a digital control circuit for controlling the electric current, in a way which is robust with respect to the voltage ripple of a vehicle on-board power system, of a control magnet valve for a motor vehicle hydraulic device with simultaneously improved dynamic behavior in response to jumps in a setpoint value current as a reference variable of the control circuit, at least one adaptive correction filter whose filter time can be adjusted dynamically on the basis of the change in level of the setpoint value current is provided in the feedback branch of the digital control circuit.