FPGA-based industrial control field monitoring system design - Power Circuit - Circuit Diagram

MOS power IC full range

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

inductance

Abstract: The interface application scheme of two input signal AD converters AD7705 and FPGA is given. With this scheme, the temperature and voltage signals in the background of industrial control can be monitored in real time. The temperature signal is obtained by converting the temperature signal into a voltage signal by using a linear relationship between the PT resistance value and the temperature change.
Keywords: PT resistance; SPI interface; AD7705

O Introduction When the whole machine is working, about 4% of the energy is consumed by various power electronic devices. These consumed energy are dissipated through the heat sink in a single module in the form of heat.
In view of the above phenomenon, the PTl00 platinum resistance temperature sensor can be used to sense the temperature on the surface of the heat sink to protect the power electronic device from damage due to operation at high temperatures. The resistance of metal platinum (Pt) varies with temperature and has good reproducibility and stability. A sensor made of this physical property of platinum is called a platinum resistance temperature sensor, and the platinum resistance temperature is usually used. The sensor has a zero-degree resistance of 100Ω and a resistance change rate of 0.3851Ω/°C. Platinum resistance temperature sensor has the advantages of high precision, good stability and wide application range. It is the most commonly used temperature sensor.
Serial Peripheral Interface (SPI) is a high-speed synchronous serial input and output port. In recent years, SPI interfaces have been widely used in the expansion of external devices such as external shift registers, DA converters, AD converters, serial EEPROMs, and LED display drivers. The SPI interface can be shared. This makes it easy to form a system with multiple SPI interface devices. Its transfer rate is programmable, the connection line is small, and it has good scalability.
The AD7705 is a typical AD converter with an SPI interface that allows easy communication with controllers with SPI modules. This article uses FPGA as the main controller, uses its general-purpose I/O port to simulate SPI timing, to acquire two input signals (temperature signal and voltage signal) of AD7705, and collect 16-bit temperature digital signal and 16-bit voltage. The digital signal is sent to the DSP for processing, and then the digital signal is algorithmically restored, and finally two actual signals are respectively displayed on the 1602 liquid crystal display, thereby realizing real-time monitoring of the temperature and voltage signals.

l Hardware design scheme The function of the system is mainly to realize real-time double monitoring of the temperature signal and voltage signal of the background device in the industrial control field. The temperature signal converts the temperature signal into a voltage signal varying from 0 to 2.5 V according to the linear relationship of the PT resistance value with temperature. Then give the l channel of the AD7705. The voltage signal can be converted into a voltage signal of O ~ 2.5 V by a transformer and sent to the 2 channels of the AD7705, thereby realizing the acquisition of two signals of temperature and voltage.
1.1 Features of P11 resistor
The PT resistance value can vary with temperature, and at 0 ° C, the resistance value is 100 Ω. When it is less than 0 °C, the resistance decreases with the decrease of temperature; when it is greater than 0 °C, the resistance increases with the increase of temperature. The relationship between the resistance and the temperature can be expressed by Equation 1 and Equation 2.
[3]