PTC Heater Output Temperature Estimation Without Fluid Sensors
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Solution Overview
Problem
Existing methods for determining the output temperature of a fluid after flowing through a PTC heater are complex and cost-intensive, often requiring temperature measurements.
Innovation Solution
Determine the output temperature of a fluid using the supply voltage, current, and duty cycle of the PTC heater without direct temperature measurements, utilizing a characterization constant derived from preliminary tests to calculate the output temperature based on the electrical heating power and temperature of the PTC heating element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to measure the output temperature of the fluid, then the output temperature can be accurately determined, but the system becomes complex and cost-intensive
Solution Approach 1:
The patent uses the electrical resistance of the PTC heating element as an intermediary parameter to indirectly determine the output temperature of the fluid. Instead of directly measuring fluid temperature with sensors, the system measures the electrical resistance of the PTC element (which correlates with its temperature) and uses this as a proxy to calculate the fluid output temperature through established thermal relationships.
Solution Approach 2:
The patent replaces the mechanical/physical temperature measurement system (temperature sensors) with an electrical measurement system. By measuring electrical resistance and using it to calculate temperature through mathematical relationships, the system substitutes direct thermal measurement with electrical measurement and computation, thereby reducing hardware complexity.
2Measurement precision
If temperature sensors are used to measure the output temperature of the fluid, then the output temperature can be accurately determined, but the system becomes cost-intensive
Solution Approach 1:
The patent creates a virtual model or mathematical representation of the thermal system that allows temperature calculation without physical temperature sensors. By using the electrical resistance characteristics of the PTC element and applying thermal-mathematical models, the system generates accurate temperature information through computation rather than expensive physical sensing hardware.
Solution Approach 2:
The patent replaces expensive, fragile temperature sensors with simple, inexpensive electrical resistance measurements of the PTC element. The electrical contacts and resistance measurement capability are inherent to the PTC heater operation, eliminating the need for additional costly sensing components that would require calibration, maintenance, and replacement.
3Temperature
If the supply voltage is increased to raise the output temperature of the fluid, then the heating power increases, but the risk of overheating increases
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors the electrical resistance of the PTC heating element (which reflects its temperature state) and adjusts the supply voltage accordingly. When the calculated output temperature approaches or exceeds a predetermined threshold, the control unit reduces the supply voltage to prevent overheating, creating a closed-loop control system that actively manages temperature safety.
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 accurate determination of the output temperature without the need for temperature sensors, simplifying the process and reducing costs while preventing overheating.
Implementation Method 1
a supply voltage is applied to the PTC heating element via the electrical contacts, thereby generating a current in the PTC heating element
Implementation Method 2
The PTC heating element is formed from a PTC ceramic and is a PTC thermistor. The electrical resistance of the PTC heating element depends on its temperature and vice versa.
Data Source
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AI summary
The invention relates to a method (7) for determining an output temperature (TOUT) of a fluid after flowing through a PTC heater (1) with a PTC heating element (2). In the method: - a current (I) of the PTC heating element (2), a supply voltage (U) of the PTC heating element (2) and a duty cycle (PWM) of the supply voltage (U) are determined, and - the output temperature (TOUT) of the fluid is calculated based on the current (I), the supply voltage (U) and the duty cycle (PWM). The invention also relates to a PTC heater (1) for carrying out the method (7).