PWM Heating Circuit Control via Average Value Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric heating circuit control systems for vehicles require either multiple setpoint wires or a microcontroller for precise control, which increases complexity and cost, especially when using PWM signals for heating elements connected in parallel.
Innovation Solution
A method and device that receive a PWM power setpoint signal over a single wire, extract an average value, and perform comparisons with distinct threshold values to generate control signals for electronic switches associated with heating elements, allowing for precise control without a microcontroller, using a divider bridge to generate threshold values and comparators to manage switching states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM control with microcontroller is used, then control precision is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts the essential control function from the microcontroller by using a dedicated PWM control input that directly interfaces with the heating elements. The microcontroller is replaced with a simplified control circuit that only needs to process PWM signals and generate appropriate switching control, removing unnecessary processing capabilities while maintaining control precision.
Solution Approach 2:
The invention replaces the expensive microcontroller with a much simpler and cheaper control circuit consisting of basic electronic components. This simplified control device, while less versatile than a microcontroller, is sufficient for the specific PWM control function and significantly reduces system cost and complexity.
2Adaptability or versatility
If logic control with multiple setpoint wires is used, then control flexibility is improved, but wiring complexity increases
Solution Approach 1:
The invention makes the single PWM setpoint wire universal by enabling it to control multiple heating elements with different power requirements. The PWM signal's variable duty cycle allows a single wire to provide multiple power levels (0%, 33%, 67%, 100%) to different combinations of heating elements, eliminating the need for separate setpoint wires for each element.
Solution Approach 2:
The invention introduces dynamic control by using PWM signals with variable duty cycles instead of static on/off control. This allows the control system to dynamically adjust the power delivered to each heating element by varying the PWM duty cycle, providing flexible power distribution through a single wire without requiring multiple setpoint connections.
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 efficient and cost-effective control of parallel heating elements by discretizing the PWM signal into multiple power levels, allowing for stepped control of heating elements using fewer components and reducing complexity, while maintaining accuracy.
Implementation Method 1
resistive heating elements connected in parallel
Data Source
AI summary
A device (1) for controlling an electrical heating circuit (2) comprising a number N of heating elements (21-23) connected in parallel, comprises, according to the invention: N electronic switches (T1-T3), each able to be connected in series with one of the N heating elements (21-23); a module (10) able to receive a power setpoint in the form of a control signal (PWM) with duty ratio varying as a function of power; means (12) for extracting a mean value (formula (I)) of the control signal (PWM) received; and P comparators (C1-C3), the integer P being less than or equal to N, which are able to compare the mean value (formula (I)) extracted with P distinct threshold values (Ref1-Ref3) and to generate P comparison signals (S1-S3), each comparison signal serving to control a toggling of the electronic switch (T1-T3) associated with at least one heating element into the open or closed position.