Introduction of automotive electronic test system solutions

　　Due to extensive cooperation with vehicle and component companies around the world, Yokogawa has many test cases in this field. Yokogawa hopes to contribute to the development of automotive electronics.

　　With the increase of electronic systems in automobiles, how to conduct high-efficiency testing of highly mechatronics automotive systems is a challenge facing Chinese test engineers. As this article addresses various test issues involved in the automotive development process, please ask Yokogawa Electric Introduce a complete solution that meets the needs of engine, drive, vibration, environmental impact, fuel cell efficiency, and CAN bus testing.

　　一. Introduction　　 With the development of the automobile industry and the electronics industry, more and more electronic technologies are applied to modern cars. Automobiles will also develop from purely mechanical products to advanced mechatronics products. As real-time driving information systems and multimedia devices are popular in automobiles, automobiles are more personalized, versatile, safe and comfortable. With the rapid development of wireless and mobile computer technology, even if you are driving alone on unfamiliar land, you will not feel lonely or lost. Cars are not only a means of transportation in people's lives, but gradually become a way of enjoying life. Research in the field of automotive electronics has become the most active part of automotive research and development, and the results achieved in this area will achieve greater returns in the market. ? This article introduces various test solutions provided by Yokogawa Electric for engine analysis, drive analysis, vibration analysis, environmental impact, fuel cell efficiency analysis, CAN bus analysis, etc. involved in the automotive development process (Figure 1). ?

　　2. Testing of fuel cells for electric vehicles?

　　For engineers engaged in automobile R&D, the following aspects are important factors that affect the efficiency and results of the test in the test:

　　(1) A variety of high-frequency and low-frequency, high-power and low-power electromagnetic radiation interference?

　　(2) Common mode voltage, vibration, and changeable environment?

　　(3) Reliability of data collection and analysis?

　　(4) What is the power supply and energy consumption of the instrument during the road test?

　　(5) Easy to move and use on site?

　　Through communication with test engineers of automobile production and R&D companies, Yokogawa continues to improve its products to make them more suitable for the needs of automobile research and development. For example, in order to meet the research needs of electric vehicle fuel cells, Yokogawa developed the DAQMaster series MX100 on the basis of the DARWIN series. ?

　　Because each battery only outputs 0.8-1.5VDC, in order to output enough power. The fuel cell stack is generally composed of about one hundred monolithic cells, especially for automotive applications, the battery pack will be composed of six hundred monolithic cells. The battery voltage monitoring (?CVM) system can detect the problematic battery by testing the voltage of each single cell in the battery pack structure; analyze the battery performance on site or during long-term operation with load.

　　Use differential input when detecting battery voltage. Although the voltage of the monolithic battery is not high, the differential input terminal will generate a voltage of several hundred volts to the ground of the test instrument. This voltage is called common mode voltage. Most data acquisition instruments (?DAQ) are not insulated, and the input voltage limit is generally 5 volts or 10 volts. In addition, non-insulated instruments are often susceptible to ground loops. In order to overcome the problem of high common-mode voltage in the fuel cell CVM system, high-voltage insulation is required. Although external signal converters or buffers can be used, in order to reduce the size and low cost while ensuring higher signal resolution and accuracy, many DAQ systems now have built-in buffers. ?

　　DAQMaster can provide the highest level of channel-to-ground, isolation between modules and channels. In addition, its modular structure and standard software make it easy for the MX100 to monitor the battery voltage of up to 1200 channels. ?

　　The design of a DAQ system that achieves both high-voltage isolation and multi-channel at the same time is a difficult problem, because most data acquisition instrument modules use a single A-D converter and a front-end multiplication or scan combination. The high common-mode voltage signal must pass through the switching relay before it is insulated and discretized by the insulating transformer and A-D converter.　　 MX100 uses Yokogawa’s patented high-voltage solid-state semiconductor relay in the scanner to achieve multi-channel input signal switching. This relay consists of high-voltage (1500VDC) and low-leakage current (3nA) MOSFETs (Metal Oxide Semiconductor Field Effect Transistor) and a voltage output photocoupler, it has the advantages of 10-channel high-speed scanning in a 1 second period, no contact, long life, no noise, etc. ?

　　In addition, the insulating transformer and integral A-D converter inside the MX100 are also Yokogawa’s patented technology. Other DAQ systems that use electromagnetic relays to provide insulation will have problems with switching time, switching stability, and routine maintenance. Finally, MX100? DAQMaster? provides high-performance isolation and 4-channel simultaneous sampling, because the hardware of each channel of the 4-channel module is composed of independent hardware. ?

　　For the correct reproduction of the waveform, the sampling rate is very important, and high-speed acquisition can obtain the correct data. For this MX??

　　The minimum measurement period of 100 is 10ms, and 3 kinds of measurement periods can be mixed in a system, and the measurement period can be set individually for each module. MX100 supports a CF card with a maximum capacity of 2G? Bytes, and it starts data backup when communication fails. When the communication returns to normal, the data transmission to the PC will start again automatically. MX100 aims at the high-speed/multi-channel/high withstand voltage/multi-cycle characteristics of fuel cell testing, helping test engineers improve the efficiency and accuracy of testing. ?

　　3. CAN bus analysis　　Automotive bus technology is widely used in today's cars. The automobile bus provides a unified data exchange channel for various complex electronic devices, controllers, and measuring instruments in the automobile. The number of components controlled by electronic control units (?ECU) in automobiles is increasing, such as electronic fuel injection devices, idle speed control (ISC), anti-lock braking devices (?ABS), airbag devices, and electronically controlled door and window devices , Active suspension, etc. With the widespread application of integrated circuits and single-chip microcomputers in automobiles, the number of ECUs in automobiles is increasing.

　　So, a new concept-the concept of onboard controller area network CAN came into being. CAN was originally a data communication protocol developed by the German BOSCH company to solve the data exchange between the control and test instruments in modern cars. According to the relevant ISO standards, the CAN topology is a bus type, so it is also called the CAN bus. . ? 　 　 With the widespread use of CAN bus, the test and analysis of bus signals in each link of automobile development, production, and maintenance have become more and more important, especially the observation and analysis of noise signals. ?Reflection noise caused by cable wiring length, terminal impedance position, or abnormal phenomena caused by overload LEVEL changes when connecting multiple contacts, you can use the DL7400 series CAN signal to trigger, capture the CAN bus signal and display its waveform. The analysis carried out according to the CAN protocol is displayed together with the waveform signal in the form of a list. The trigger condition can be set to a field or multiple fields of the CAN data frame (ID, ?Data, ?RTR?bits, etc.). The trigger can also be activated in the error frame. The captured CAN bus waveform data can be analyzed on the time axis, and the ID and data of each frame are displayed in hexadecimal or binary symbols. ?

　　Four, battery voltage fluctuations during ABS operation?

　　The ABS control device monitors whether the wheel is locked by comparing the signal from the speed sensor attached to each wheel. When the ABS control device detects that a wheel is locked, it sends a signal to the ABS transmission device to open the valve. ABS transmission device includes spiral pipe valve, pump, motor, brake fluid tank. Opening the valve can instantly reduce the disc hydraulic pressure, weaken the braking force, and restore the wheel speed.

　　Then quickly increase the disc hydraulic pressure again, and increase the braking force through the ABS transmission. In other words, the brake can be prevented from being locked by increasing or decreasing the disc hydraulic pressure. Increasing the disc hydraulic pressure means using a pump to press the liquid into the cylinder, which will make the pump motor work quickly. This fast motor will affect the PWM current signal that controls the solenoid valve. General ABS operation can not get whether this affects battery voltage fluctuations. Therefore, it is necessary to observe this battery voltage fluctuation. ?

　　Using DL750?Max.1GW long memory, high-speed sampling and capturing of all braking actions from the beginning to the end can be achieved. You can also use the zoom function to test an irregular part in detail after capturing the overall process. This function can automatically set the automatic test area of the waveform parameters, including the magnified area. This zoom function can not only accurately test the irregular part of a cycle, but also automatically test the waveform parameters in the zoomed area. ?

　　V. Power steering wheel control ECU (including frequency converter)/motor development Power steering wheel (EPS) has become more popular in small cars, but 3-phase motors are required for applications in large cars that require large torque. Different from the traditional For DC machines, testing 3-phase AC motors requires a power meter to test power and efficiency. In addition, if CAN bus communication is used between ECUs, CAN bus signals must also be tested.

　　DL7400 can trigger on specific ID/Data on CAN bus to realize synchronous observation with other signals. The general-purpose oscilloscope DL1640/DL1740 can test the CPU signal of ECU, using 100MHz differential probe and 150A current probe can also test the surge current of the motor. DL750 has a maximum of 16 channels of insulated input, which is suitable for long-term observation of inverter input and output voltage/current and ECU control signals.

　　WT1600 can evaluate the 3-phase current/voltage/power and inverter efficiency at the primary end DC and the secondary end of the 3-phase drive system inverter for EPS for large cars. Cumulative power test can also be performed for specific operating modes. Use WE7000's time module/CAN module/isolated A/D module/temperature module to realize multi-channel comprehensive test. Multiple channels such as steering angle/current consumption/voltage/temperature can be tested at the same time for a long time. Using the CAN module can simultaneously convert the data on the CAN bus into physical quantities for simultaneous testing.

　　6. Direct injection diesel engine injection experiment?

　　Direct-injection diesel engine can reduce fuel costs and purify exhaust emissions. The following is the key to its development-high-pressure injection and electronic control performance evaluation methods to propose solutions:

　　(1) Evaluation of the design value of the mechanical part (injection time and injection pressure)?

　　The test object is the injection pressure of the fuel injected by the nozzle, the change of the engine speed and the opening and closing time of the solenoid valve of the nozzle. Engine development requires dynamic testing (gradually increase the engine speed to check whether it meets the design requirements) and static testing (check whether it is running stably under a fixed speed).

　　(2) Synchronous test with ECU control signal?

　　Test synchronously with ECU control signal,? Test ECU timing and actual injection timing.

　　Seven, this article summary

　　Due to extensive cooperation with vehicle and component companies around the world, Yokogawa has many test cases in this field. Yokogawa hopes to contribute to the development of automotive electronics.