SBA Heater PWM Control for Constant MEMS Temperature
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Solution Overview
Problem
Micro-Electro-Mechanical Systems (MEMS) devices in sensor block assemblies face performance variations due to temperature changes and heat generation, and the existing SBA heater control system's response time is not instantaneous enough to maintain a predefined temperature, especially with varying battery power source voltages.
Innovation Solution
A root mean square (RMS) pulse width modulation (PWM) control system is implemented, which generates a control signal to adjust the duty cycle of a switch coupled to the heating resistor, ensuring a substantially constant power delivery to the resistor despite changes in input voltage, thereby maintaining a stable temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional PWM control system is used to control the SBA heater, then the system is simple to implement, but the response time is not instantaneous and the heater may overheat the MEMS device when power supply voltage changes
Solution Approach 1:
The patent implements a dynamic control system that continuously monitors the power supply voltage and adjusts the PWM duty cycle in real-time. The control system calculates the required duty cycle based on the current voltage level to maintain constant power delivery, transforming the static PWM approach into a dynamic response system that adapts to voltage fluctuations instantaneously
Solution Approach 2:
The patent employs a feedback mechanism where the control system monitors the actual power delivery to the heater and compares it with the desired power level. Based on this feedback, the system adjusts the PWM duty cycle to compensate for voltage variations, ensuring accurate temperature control and preventing overheating conditions
2Adaptability or versatility
If the battery power source is used to power the SBA heater, then the system is portable and self-contained, but the output voltage changes as power is consumed or recharged, affecting heater performance
Solution Approach 1:
The patent changes the control parameter from a fixed duty cycle to a variable duty cycle that is a function of the power supply voltage. The control system calculates the appropriate duty cycle based on the current voltage level, allowing the system to adapt to voltage changes caused by battery discharge or recharge cycles while maintaining stable power delivery to the heater
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
The RMS PWM controller effectively maintains a constant power delivery to the heating resistor across varying input voltages, improving the SBA heater's response time and maintaining the MEMS device within a predefined temperature range, even with fluctuations in power source voltage.
Implementation Method 1
devices within the MEMS device and the SBA, including the SBA controller, generate heat while operating due to resistive loading losses
Data Source
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AI summary
Systems and methods source a heating resistor to control temperature. For example, a sensor block assembly (SBA) heater controls the temperature of a MEMS device in a sensor block assembly. An exemplary embodiment generates a root mean square (RMS) pulse width modulation (PWM) control signal based upon an input voltage from a power source, controls a switch in accordance with the RMS PWM control signal; and sources a heater resistor from the power source in accordance with the controlling of the switch. Power to the heating resistor is controlled by the switch to provide a substantially constant value of power to the heating resistor for varying values of the input voltage.