Research and Development of Multi-function Electronic Tester for Automotive Generator Voltage Regulator

Abstract: Using electronic analog generators instead of automobile generator sets, a static test system for automotive voltage regulators was developed. The system uses a computer as an application platform, combining the latest integrated devices and electronic application technologies. The trial shows that the test system is suitable for the detection of multiple parameters of a variety of products, with the characteristics of accurate test, stable and reliable, simple operation and high intelligence. The test accuracy can reach 0.1% of the dynamic test, which is very popular.
Key words: automobile generator; voltage regulator; data acquisition; static test

0 Introduction Automotive generator voltage regulators are a key component of automotive power supply systems. Their purpose is to stabilize the output voltage of automotive generators from generator speed changes and load changes. The quality of the product is directly affected by the normal driving of the vehicle.
For many years, the electrical performance test of automotive generator voltage regulators has been used in the traditional method of testing on generator test benches. Because the entire test system is huge, expensive, consumes a lot of power, and is complicated to operate. Therefore, only the regulator production plant has the test system, and the general use unit and the automobile electrical maintenance unit do not have the conditions for using the test system. Therefore, the electrical performance test of the automobile generator voltage regulator has been a problem that plagues the motor factories and the maintenance market.
Automotive generator voltage regulator Multi-function electronic test equipment is an electrical performance test instrument that is urgently needed in the automotive industry for many years, whether it is a motor factory or a maintenance market. The multi-function tester uses a computer as the application platform, combined with the latest integrated devices and electronic application technology, with the characteristics of accurate test, stable and reliable, simple operation and high intelligence. It will replace the existing huge automobile generator voltage regulator. The test system is a research topic that fills the domestic gap.
After the automobile generator voltage regulator multi-function electronic test instrument is promoted and applied in related fields, it will achieve higher social and economic benefits. The developed BL-2 single-function voltage regulator static tester has become a test instrument for many voltage regulator manufacturers and generator manufacturers in China, but it is only suitable for testing small and medium-sized, single-function voltage regulators. Can not meet the functional needs of the market. To this end, the BL-4 type multi-function voltage regulator integrated parameter static tester has been developed, which is suitable for the detection of multiple parameters of different products such as three-pin single function, multi-pin single function, multi-pin multi-function.

1 Design of test signal acquisition and conversion circuit The main parameters of automotive voltage regulator are regulated voltage value, speed characteristic, load characteristic, temperature compensation coefficient and saturation voltage drop. The speed characteristic and load characteristic are related parameters related to generator matching. It is not suitable for static testing and must be tested dynamically on the generator test bench.
1.1 Static test of multi-pin multi-function voltage regulator This regulator is suitable for generators equipped with non-excited rectifier. The regulator has dual functions, namely regulator function and indicator function. The typical product is Xiali. The 7-pin regulator for the generator has its external circuit connected as shown in Figure 1. Since the regulator function and the charge indicator control function are independent of each other, the two functions can be statically tested separately.

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Regulator function: B+, IG, S, W can be connected to the tester + pole together, F, E are connected to the corresponding terminal of the tester (as shown in Figure 1), L is connected to the indicator light and then connected to the positive pole. The value indicated by the voltmeter is the adjusted voltage value. Disconnect the W end from the positive pole and the indicator light is on; if the indicator is off, the indicator light is normal, otherwise it is abnormal.
1.2 Three-pin single-function regulator test
1.2.1
Test circuit for adjusting voltage value is shown in Figure 2. Test principle: input the power into the electronic analog generator. When the regulator is not connected, the generator +, - pole output battery voltage, about 8 ~ 10 V when measuring 14 V regulator, about 16 ~ 20 V when measuring 28 V regulator When the pins of the regulator are respectively connected to the electronic analog generator according to the polarity, the value displayed by the voltmeter is the regulated voltage value of the regulator. This method is used to measure the adjusted voltage value without manual adjustment, accurate data and high efficiency. The measurement accuracy depends on the electronic analog generator.

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1.2.2 Test circuit for measuring the conduction voltage drop at the output terminal The test circuit for the conduction voltage drop at the output terminal (ie, the power tube conduction voltage drop) is shown in Figure 3. Adjust the resistance R to the current specified value, at which point the voltmeter reading is the regulator conduction voltage drop. The lower the pressure drop, the smaller the regulator's own consumption.

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1.3 Multi-Pin Single-Function Regulator Static Test The multi-pin single-function regulator can also be tested in a static manner. Because of any voltage regulator, only three electrodes are necessary and indispensable. E, B+, F, and other pins all have auxiliary functions. As long as the auxiliary pins are technically processed, they can be tested in a static method.

2 data acquisition system design
2.1 Hardware Design The
data acquisition system consists of signal conditioning circuit, multi-channel switching circuit, sample-and-hold circuit, A/D conversion circuit and signal processing circuit. Its hardware structure block diagram is shown in Figure 4. The A/D conversion module uses the ADC0809 chip, which is a CMOS single-chip successive approximation A/D converter with eight analog switches, an address latch and decoder, a comparator, and an 8-bit switch D/A converter. And successive approximation registers to meet the requirements of this system. The signal processing module uses AT89C51 single-chip microcomputer, which is a low-power, high-performance 8-bit single-chip microcomputer with a 4 KB FLASH programmable, erasable read-only memory (PEROM) on the chip, using CMOS technology and ATMEL. The company's high-density non-volatile memory (NURAM) technology, and its output pin and command system are compatible with the MC S-51. It is a powerful, flexible and affordable microcontroller that is suitable for use in this system. The communication interface uses the standard interface of RS 232 asynchronous serial communication, and uses the MAX232 chip to convert between RS 232 and TTL level.

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2.2 Data Acquisition System Software design system support software is divided into two types: assembly service program and man-machine interface high-level language processing program. The organic combination of the two achieves the goal of high-speed control, simple operation interface, friendly interaction and complete functions.

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The assembly service program mainly includes the main program, the A/D conversion program and its interrupt service program, the ASCII code conversion program, and the serial communication program. The modular design method is adopted in the program design, and each function module is relatively independent and is called by the main control module. The modules are well-defined, clear-cut, and readable, which greatly facilitates software debugging and porting. The main program and ASCII code conversion subroutine are given here. The main program mainly completes the preparation work of calling each subroutine and interrupt service program, and the program flow is shown in FIG. 5. The data collected by the ASCII conversion subroutine capture card must be converted to ASCII code before being output to the computer for display on the screen. The program flow is shown in Figure 6.

3 Visual interface software design to provide users with convenient graphical interface and comprehensive data information, using Visual Basic language for human-machine interface design, including parameter setting, data display, data output three main functions, the operation process is shown in Figure 7 is shown. Figure 8 shows the voltage value acquisition interface. When the software is running for the first time, you need to set the function configuration area in the lower right corner of the screen. Global settings include settings such as acquisition frequency, value period, whether to automatically save and automatically save the number of values. The voltage value calibration is to ensure that the software display data and the tester panel display data are consistent. When performing voltage value calibration settings, the tester power must be turned on first, and the capture card must be properly connected to the computer. Product maintenance is the qualified range for configuring the product data to be tested. Test data outside this range is unqualified and must be properly configured.

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4 test results analysis BL-4 multi-function voltage regulator static tester shown in Figure 9, consisting of the test part and the data acquisition part. The test part is used to test the electrical performance parameters of the automotive voltage regulator, and can display the output data. The principle structure is shown in Figure 10, including power supply, electronic analog generator, control, output, operation and adjustable load. The power section is equipped with three sets of switches for testing different parameters of different series of products. The function of the data acquisition system is to transfer the test results of the voltage regulator test system to the computer, and record and save the data through the human-machine interface for batch analysis and processing of data.

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The test room temperature is 23 ° C, the generator speed is 6 000 rpm, the 14 V regulator load current is 9 A, and the 28 V regulated load current is 5 A. The regulated voltage values ​​of the dynamic test and the static test are shown in Table 1. It shows that the static test result is close to the dynamic test result, and the relative error is less than 0.14%, which meets the regulator standard requirements.

5 Conclusion After more than one year of trials, the BL-4 multi-function voltage regulator integrated parameter tester is easy to operate and low in cost. It is suitable for testing small and medium-sized, single-function voltage regulators, as well as for mass production. Multi-function voltage regulator test, and can further statistically analyze, analyze and predict the performance and reliability of large-volume products. The test accuracy can reach 0.1% of dynamic test, which is higher than similar products on the market and has strong promotion. .

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