PTC water heater overcurrent detection software and hardware dual protection circuit

Abstract

The invention provides a positive temperature coefficient (PTC) water heater over-current detection software and hardware dual protection circuit which is high in sampling precision, short in response time, capable of providing dual protection for software and hardware and low in requirement for printed circuit board (PCB) Layout. The PTC water heater over-current detection software and hardware dual protection circuit comprises a constantan wire sampling resistor with the precision being one percent, and the constantan wire sampling resistor transfers a current signal into a voltage signal which is sent to an amplifying circuit composed of U1B, R13, R15, R16 and C4. The signal which is amplified by 1+R16 / R15 times is sent to a comparator circuit composed of U1A, U2, R12, R15, R16 and C3. When the voltage is higher than a fiducial voltage stabilizing value (VCC / 2), a comparator outputs a saturation VCC voltage, and the output VCC voltage is fed back to the in-phase end of the operational amplifier U1A through D3 and R7, and thus the comparator is in a state that the saturation voltage VCC is output forwards in a self-locking mode. An audion Q3 is electrified through the output voltage, and then pins can be pulled down through an insulated gate bipolar transistor (IGBT) driving module, so that an IGBT is closed.

Description

technical field [0001] The invention relates to an automobile accessory, in particular to a PTC water heater overcurrent detection software and hardware dual protection circuit. Background technique [0002] PTC is the abbreviation of Positive Temperature Coefficient, which means a positive temperature coefficient, and generally refers to semiconductor materials or components with a large positive temperature coefficient. As a new type of thermistor material, its main application can be divided into two categories: switching and heating. Utilizing the characteristics of heating PTC, such as stable performance, rapid temperature rise, and little influence from power supply voltage fluctuations, various heater products have become the most ideal substitute products for metal resistance wire heating materials. At present, it has been widely used in automobile air conditioners, electric vehicle air conditioners, electric vehicle defrosters, etc. [0003] The PTC water heater u...

AI Technical Summary

Problems solved by technology

At present, the overcurrent detection of high-current power devices is most commonly implemented using the Hall current sensor solution. However, the temperature drift of the Hall sensor is relatively serious, and the price is high, and there are specific requirements for the location and layout of the sensor.

Images