Method for accurately measuring the remaining battery capacity of a portable device

I. Introduction

With portable electronic products, it is hoped that you can know the remaining battery power, the continuous working time, and adjust the related applications accordingly. This will be a very convenient thing, especially for business people who use smart phones. Battery power detection technology is common in laptops, and most laptops have power management options that provide different power modes and battery alarms. But in the more compact portable product market, this technology is still rare.

Portable products offer more and more functions, and users increasingly need to accurately monitor battery power to flexibly manage available power, clearly display remaining working hours, and maximize system uptime. The current electricity measurement method used by most mobile phones is still relatively simple and lacks precision. The current mainstream detection method is to simply measure the battery voltage and estimate the corresponding battery remaining capacity. The total power is divided by 4 or 5, which is the battery of 4 or 5 grids that can usually be seen on the screen of the mobile phone. Therefore, the accuracy of each grid is 25% or 20%. This accuracy obviously cannot meet the high precision requirements. Applications.

The method for estimating the amount of electricity is usually as follows: When a battery is discharged, the voltage of the battery gradually decreases as the battery power is lost. In this way, a relatively simple and effective correspondence can be obtained, that is, the voltage corresponds to the capacity. Through the discharge curve of the normal use of the battery (such as 100mA discharge), the time is divided into 4 equal parts, and the lithium battery with the charging limit voltage of 4.2V is taken as an example, and such a correspondence relationship can be listed, 4.20V-100%, 3.85V- 75%, 3.75V - 50%, 3.60V - 25%, 3.40V - 5% (because the mobile phone is not able to fully use the power of the photocell, it is usually turned off automatically when it is lower than 3.40V). Obviously, this accuracy is only 25%. In addition, the battery voltage will abruptly change with the power transmission of the RFPA, which usually becomes 0.2V-0.3V. If you use the voltage to simulate the power method, the error will be even greater. In order to solve the measurement problem that the battery voltage suddenly becomes small, the current method of engineers is to use the software algorithm to perform the mean filtering to average the battery voltage over a period of time. If the average battery voltage of the time period does decrease, then It is estimated that the power is actually reduced, otherwise the power is not changed.

The method of calculating the remaining battery power by the battery voltage does have defects, and the method of calculating the remaining power by real-time monitoring of the battery power consumption by the coulomb counter is very accurate. Fairchild's FAN4010 is a typical device for this application. It is a current detecting sensor designed to detect the charging/current consumption current of a portable device battery. It can convert the current signal through the precision detecting resistor into a voltage signal that can be detected by the ADC, thereby calculating the actual power consumed for a period of time. .

Second, the typical design of the hardware circuit

In order to meet the high-precision battery fuel monitoring requirements, the FAN4010 can be used to meet the requirements by adding appropriate application circuits and adding specific software control algorithms. Figure 1 is a block diagram of a typical application of the FAN4010. Only two resistors Rsense and Rout are required to form a high-precision amplifier circuit. Figure 2 is a schematic diagram of the internal structure, so there is Vsense = I_load * Rsense, Vout = 0.01 * Vsense * Rout, so the two relations can wait until I_load = 100 * Vout / (Rout * Rsense), so as long as the ADC is used to monitor Vout The voltage on the voltage is divided by the known resistance values ​​Rout and Rsense to obtain an accurate load current consumption, and the current is integrated over time, that is, the accurate value of the consumed power can be achieved. By subtracting the exact power consumption value from the total power, you can get the accurate remaining power. The charging circuit is the same.

Figure 1 Application block diagram of FAN4010

Figure 2 Schematic diagram of the internal structure of the FAN4010

The typical application diagram of FAN4010 and the selection requirements of Rsense and Rout are as follows. 3 is a charging circuit of the battery, and FIG. 4 is a discharging circuit of the battery.

Figure 3 Reference schematic of the charging part

Figure 4 Reference schematic diagram of the discharge part

Our company can use different materials to make pump grade according to the well condition. The pump for high sand content and high gas well can be provided completely according to customer requirements. Our company has a professional design team, advanced production equipment, first-class service team, and continuous quality assurance for customer service.

513series Petroleum Submersed Pump

513Series Petroleum Submersed Pump,Petroleum Submersed Pump,Water Pump,Electric Pump

Tianjin RongHeng Group LLC , https://www.wholesale-water-pump.com