Magnetic Valve Coil Temperature Estimation via Thermal Model Correction
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Solution Overview
Problem
Existing methods for determining the temperature or resistance of magnetic valves during control phases are inaccurate due to heat-induced resistance changes, leading to inconsistent valve conditions when using the same PWM signal at varying temperatures.
Innovation Solution
A method that estimates temperature development using a thermophysical model, corrected by direct or indirect temperature measurements, and accounts for temperature deviation parameters (KC, KH) to accurately determine the magnetic coil's resistance during control phases, utilizing a simplified Kalman filter characteristics curve for reduced computational power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance measurement is performed directly via voltage measurement, then measurement precision is improved, but the measurement can only be performed when the valve is not being controlled
Solution Approach 1:
The patent performs resistance measurements during intervals when the valve is not being controlled (when PWM duty cycle is 0% or 100%). These preliminary measurements are stored and used to calculate temperature compensation factors before actual control operations, enabling accurate temperature compensation during control phases without requiring measurements during those phases.
Solution Approach 2:
The patent creates a thermal model that copies and simulates the temperature behavior of the magnetic valve based on limited measurements taken during non-control periods. This thermal model then provides continuous temperature estimates during control phases, effectively copying the temperature information that would be difficult to obtain directly during active control.
2Duration of action of moving object
If a thermal model is used to estimate temperature during control phases, then control availability is maintained, but measurement precision deteriorates due to model approximation errors
Solution Approach 1:
The patent implements feedback by continuously updating the thermal model with actual resistance measurements taken during non-control intervals. The measured resistance values are used to correct and refine the model's temperature estimates, ensuring that the model remains accurate over time while maintaining continuous control capability.
Solution Approach 2:
The patent changes the operational parameters of the system by switching between measurement mode (0% or 100% PWM duty cycle) and control mode. During measurement mode, the system captures accurate resistance data; during control mode, it uses the thermal model with updated parameters to maintain accuracy without requiring direct measurements.
3Ease of operation
If PWM control is applied to the magnetic valve, then valve actuation is achieved, but heat loss is generated which changes the resistance and impairs control accuracy
Solution Approach 1:
The patent converts the harmful effect of heat generation during PWM control into a beneficial measurement opportunity. By intentionally creating conditions where the valve is off (0% PWM) or fully on (100% PWM), the system generates thermal states that allow resistance measurements to be taken, which are then used to improve control accuracy through temperature compensation.
Solution Approach 2:
The patent dynamically adjusts the PWM duty cycle to alternate between measurement phases (0% or 100%) and control phases. This dynamic switching allows the system to continuously update its thermal model and maintain accurate control despite the changing thermal conditions caused by PWM actuation.
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
Enables precise temperature and resistance determination of magnetic coils during valve control, improving the accuracy of control interventions by recalculating resistance values from voltage measurements and adjusting PWM signals accordingly.
Implementation Method 1
a coil for generating a magnetic field by which an armature is actuated. The magnitude of the current flow determines the strength of the magnetic field
Implementation Method 2
During the control of a magnetic valve, for instance, within the scope of an ESP regulation, a heat loss is generated which leads to the heating of the magnetic valve. This raises the ohmic resistance of the valve
Data Source
AI summary
A method for determining the temperature or the ohmic resistance of an electrical component, especially of a coil of a magnetic valve. The component temperature is estimated with the aid of a temperature model, which is able to determine the curve of the component temperature even during a control of the valve. The temperature model is corrected regularly based on the measured value, in this context.