US Patent 11673348 Heat seal bar sensorless temperature sensing and control

A sensorless temperature sensing and control system and method uses electrical voltage and current feedback signals to monitor and control the temperature of heating elements used in a heat sealing process wherein sensors are not physically connected to a heat seal bar during the heat sealing process. After calibration of a heat seal bar using a sensor, voltage and current feedback signals are processed by a programmable logic controller (PLC) to calculate the real-time electrical resistance of each heating element. Data and electrical resistance is used to calculate real-time temperature of the heat seal bar during heating.