High-Temperature Molten Salt Weighing & Control System
Designed a high-temperature electronic mass balance system for molten salt handling in utility-scale battery manufacturing. The system measures up to 2 kN with 1 cN resolution, performs temperature compensation from 20–100°C, and controls both molten salt flow and cooling cycles through relay actuation. The block diagram illustrates a modular architecture centered on an STM32F103C8T6 microcontroller, integrating an LCM307 load cell with HX711 24-bit ADC for high-resolution weight measurement, an RTD temperature sensing chain with analog signal conditioning and ADS1115 ADC for thermal compensation, relay-driven flow and cooling control, and RS-232 communication via MAX3232 for 100 ms digital data transmission.
The circuit schematic details the full analog front-end design, including:
Constant-current RTD excitation using a BJT current mirror
Differential amplification and precision voltage scaling to map temperature to 0–5 V
24-bit load cell signal conditioning using HX711
NPN transistor relay drivers for flow interruption (<10 ms response) and cooling control
AC–DC conversion using a MEAN WELL RS-15-5 power module (120 VAC to 5 VDC)
A temperature-drift compensation lookup and interpolation scheme ensures ±1% accuracy even beyond the load cell’s native compensation range. The system maintains thermal isolation between sensor and electronics and satisfies industrial constraints on power consumption (<2 A) and relay ratings.
This project demonstrates full-stack instrumentation design: sensor physics, analog signal conditioning, embedded control logic, communication interfacing, and industrial reliability considerations.
