Coil Temperature Measurement Using Thermal Equivalent Circuit
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Solution Overview
Problem
Existing keyboard instruments with soundboards face issues of excessive coil temperature due to large currents, leading to potential abnormal events or burning, and existing protection technologies do not accurately measure or manage coil temperature.
Innovation Solution
A temperature measurement device for acoustic signal converters that includes an ambient temperature detector and a computing section to calculate coil temperature using a thermal equivalent circuit, allowing for accurate temperature measurement and protection by adjusting energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large current flows through the coil to vibrate the soundboard, then the acoustic signal output is improved, but the coil temperature excessively rises causing abnormal events or burning
Solution Approach 1:
The system performs preliminary temperature measurement before energizing the coil and during operation. The temperature measurement device detects ambient temperature and calculates coil temperature in advance to prevent excessive heating before it occurs, allowing the system to adjust or prevent energization when temperature thresholds are approached.
Solution Approach 2:
The temperature measurement device continuously monitors coil temperature and feeds this information back to the control system. Based on the measured temperature, the system automatically adjusts the energization state of the coil, reducing power when temperature is high and allowing full power when temperature is acceptable, thus resolving the contradiction between power output and temperature control.
2Measurement precision
If temperature measurement device is added to protect the coil, then protection accuracy is improved, but device complexity increases
Solution Approach 1:
The temperature measurement device acts as an intermediary between the coil and the control system. It includes a temperature detector that measures ambient temperature and a calculator that computes coil temperature based on thermal equivalent circuits, providing accurate temperature information without requiring direct contact with the coil or complex measurement systems.
Solution Approach 2:
The system replaces complex direct temperature measurement mechanisms with an electrical calculation approach. Instead of using sophisticated thermal sensors directly on the coil, the system uses electrical parameters (voltage, current, resistance) and thermal equivalent circuit models to calculate temperature, simplifying the physical measurement infrastructure while maintaining accuracy.
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 solution enables high-accuracy temperature measurement and protection of the coil and its peripherals by preventing excessive temperature rises, thus preventing abnormal events and ensuring the instrument's safety.
Implementation Method 1
an ambient temperature detector (21) for detecting an ambient temperature (Ta) of the acoustic signal converter
Implementation Method 2
the computation including calculation of an amount of electric power (P) consumed in the coil using the input voltage
Implementation Method 3
executing computation based on a thermal equivalent circuit of the acoustic signal converter using the input voltage and the detected ambient temperature (Ta)
Implementation Method 4
an acoustic signal converter including a coil (16) and being configured to convert an electric signal into an acoustic signal through energization of the coil
Data Source
AI summary
An audio signal that is output from a sound source circuit (14) is caused to flow through a coil (16) in a transducer for vibrating a soundboard, and the vibration of the soundboard generates an acoustic signal. A microcomputer (30) calculates a temperature of the coil (16) with high accuracy by inputting an ambient temperature (Ta) detected by an ambient temperature sensor (21) and a voltage (V) applied to the coil (16) and executing computation based on a thermal equivalent circuit of an acoustic signal converter using the ambient temperature and the voltage that are input thereto, the computation including calculation of an amount of electric power consumed in the coil (16) using the input voltage.