[Iboard Electronic School] [ihmi43] demonstration example: Electrical tester Demonstration Project

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I. Engineering Overview I. Introduction

The AC electrical parameter tester is a commonly used measuring instrument in the industry and has typical representativeness. Based on the hardware resources of iboard Emy, ihmi43 LCD module, and ihmi70 LCD module, this project uses a computer software virtual AC Electrical Parameter generator and connects the above hardware, form a complete measurement and display system.

2. Engineering Resources

II. Description of AC Electrical Parameters

To understand this project, we need to understand the meanings of the following AC electrical parameters. This article is only a brief introduction. For more information, see textbooks.

AC:The voltage or current that both the size and direction change cyclically over time is called AC.

AC voltage:Generally, the AC voltage is the valid value of the voltage.

AC current:Like AC voltage, AC current is also a valid value.

AC frequency:The frequency of alternating current changes in a unit of time is called the alternating current frequency. The Unit is Hz ). The Mains Frequency in China is 50Hz, and the commonly used mains frequency in the world is also 60Hz.

Active Power:The electric power required to maintain the normal operation of the power equipment, that is, the electric power that converts the power into other forms of energy (mechanical energy, light energy, heat energy), called active power, also known as average power. The instantaneous power of an alternating current is not a constant value. The average value of the power in a cycle is called the active power. It refers to the power consumed by the resistance part of the circuit, represented by P, the Unit is mainly W, KW, and MW ).

Reactive Power:In a circuit with inductance or capacitance, the power supply energy is stored in a magnetic field (or electric field) energy for each half cycle, and then released, the stored magnetic field (or electric field) energy is returned to the power source, but this energy exchange does not actually consume energy, it is called "reactive power ". The reactive power is represented by the letter Q. The common units are var, kvar, and mvar ).

Depending on the power:The product of the port's voltage valid value and current valid value is called the apparent power, represented by the letter S, in the unit of V-ampere (VA ).

Power Factor:In an AC circuit, the cosine of the phase difference between voltage and current is called the power factor, expressed by the symbol cos Phi, the power factor is the ratio of active power to apparent power, that is, cos Phi = P/S.

 

III. Hardware connection mode I. Hardware connection to iboard Electronic School

You can connect the arm UART of iboard Emy to the computer by using the itool 8-in-One debugger or U conversion string ..

 

Ii. ihmi43 LCD Module hardware connection

The ihmi43 LCD module consists of three types of external communication interfaces: UART (TTL level), RS-232 interface and RS-485 interface. We can connect to a computer through any interface. The three interfaces have their own advantages and disadvantages.

 

 

IV. PC software I. Software operations

The host computer software is written in open-source QT 4.8.4. The target file is a green software without installation. For details, see the file. The Kung Fu Panda icon is an executable file and a library required for other DLL bits. Double-click kung fu pandatv.

 

When it is enabled, the software automatically finds the connected hardware. If there is no connection, the software shows that no hardware is found, as shown in. You can also click [search for hardware] To search for connected hardware (including iboard, ihmi43, and ihmi70 ).

If the hardware is correctly connected, the connected hardware is automatically searched. The simulated sending automatically turns green, as shown in.

After finding the hardware, we can communicate with the lower computer. The software sends data to the lower computer continuously after 200 ms, and the lower computer receives and displays the data.

Ii. Software Algorithm

The software generates data in two steps.

1. voltage, current, frequency, and power factor are generated using random numbers.

2. Calculate the active power, reactive power, and apparent power. After smooth filtering, it is sent to the lower computer.

If the voltage is u, the current is I, and the power factor is cos, then:

 

V. Lower Computer Software I. Software burning

The lower computer software is divided into three versions, which are applicable to the iboard electronics School, ihmi43 LCD module, and ihmi70 LCD module. The software is based on Keil MDK 4.60.

Ii. Screen

After a 4.3-inch screen (4.3-inch screen for iboard and ihmi43) is installed and started, see the following figure.

 

 

7-inch screen (ihmi70) software.

 

 

Vi. project package, Source code Package download

Http://pan.baidu.com/share/link? Consumer id = 308846 & UK = 4247225764

 

VII. The hardware and Development Board used in this project are as follows:

Purchase address:

Http://item.taobao.com/item.htm? Id = 15851248846

 

Purchase address:

Http://item.taobao.com/item.htm? SPM = a1z10.1.137644-251734891.23.xzgnbf & id = 20508376359