Motor Vehicle Heating Device Thermal Management Strategy
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Solution Overview
Problem
Existing electrical heating devices in motor vehicles face challenges in effectively managing temperature to prevent overheating, which can damage surrounding components, especially in high-temperature conditions, and existing solutions do not adequately control the electrical supply to resistive elements to prevent overheating.
Innovation Solution
A thermal management method that controls the electrical supply of resistive elements based on predefined temperature thresholds, adjusting the power setpoint or duty cycle to prevent overheating, including stopping the electrical supply when maximum temperature is reached and resuming it when the temperature drops below a resumption threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electrical heating device operates at high power to heat the fluid efficiently, then the heating performance is improved, but the risk of overheating and damaging surrounding components increases
Solution Approach 1:
The control unit monitors temperature in advance and takes preventive action by lowering the power setpoint when temperature thresholds are approached, before overheating damage can occur. This proactive temperature management allows the system to maintain high power operation when safe while preventing harmful overheating.
Solution Approach 2:
The system continuously monitors the temperature of the heating device and uses this feedback to dynamically adjust the power setpoint. When temperature exceeds predefined thresholds, the control unit reduces power; when temperature decreases, power is restored. This closed-loop feedback enables safe high-power operation while preventing overheating damage.
2Reliability
If the temperature control is strictly enforced to prevent overheating, then the safety of surrounding components is improved, but the heating efficiency and productivity deteriorate
Solution Approach 1:
The power setpoint is made dynamic rather than fixed, automatically adjusting based on real-time temperature conditions. The system operates at high power when temperature is low to maintain productivity, and reduces power only when temperature thresholds are approached to ensure safety. This dynamic adaptation resolves the contradiction between safety and efficiency.
Solution Approach 2:
The control unit changes the power parameter dynamically based on temperature measurements. By adjusting the power setpoint according to temperature thresholds, the system maintains high heating efficiency during normal operation while ensuring component safety when temperature increases, thus resolving the contradiction between productivity and reliability.
3Reliability
If the electrical supply is completely stopped when maximum temperature is reached to prevent damage, then the protection effectiveness is improved, but the response time to recover heating function increases
Solution Approach 1:
Instead of completely stopping the electrical supply at the first sign of overheating, the system applies partial action by lowering the power setpoint to a reduced but non-zero level. This allows the heating function to continue at a reduced capacity, providing protection while maintaining some heating capability and enabling faster recovery when temperature decreases.
Solution Approach 2:
The control unit continuously monitors temperature and periodically adjusts the power setpoint based on current conditions. When temperature exceeds thresholds, power is reduced; when temperature decreases below thresholds, power is restored. This periodic monitoring and adjustment ensures effective protection while minimizing recovery time through rapid response to temperature changes.
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
Effectively prevents overheating by gradually reducing the setpoint as temperature thresholds are exceeded, stopping the electrical supply when maximum temperature is reached, and resuming it when safe, thus protecting the heating device and surrounding components.
Implementation Method 1
The heating modules comprise resistive elements, for example PTC resistive elements (PTC being the acronym of positive temperature coefficient)
Implementation Method 2
the ohmic value of PTC resistive elements increases very rapidly beyond a predetermined temperature threshold
Data Source
AI summary
The invention concerns a heat management method for an electric heating device comprising at least one subassembly of resistive elements configured to be electrically supplied and a support for a circuit supplying power to the resistive elements, wherein the power supply of the resistive elements is controlled according to a power setpoint (P_(sub)system_target_0) or temperature (T_(sub)system_target_0) or electrical current amplitude (i_(sub)system_target_0) or resistance (R_(sub)system_target_0), or even a duty ratio of the control signal (PWM_(sub)system_target_0). According to the invention, the method comprises the following steps: recording the temperature (T_PCB) of the support of the circuit supplying power to the resistive elements, comparing the recorded temperature (T_PCB) with at least one predefined temperature threshold (T1), and if the recorded temperature (T_PCB) is greater than or equal to the at least one predefined temperature threshold (T1), generating a command to reduce the setpoint by a predetermined step. The invention also concerns a corresponding heat management strategy and control unit.