The drive train of a car is essentially a system that includes an engine that powers the car (a conventional internal combustion engine) and transmits the power to the gearbox, the drive shaft, and finally to the wheels of the car. Electrification of the drive train is changing the future of automotive technology, as well as from sustainable energy drivers, improved fuel efficiency, and compliance with relevant CO2 emissions regulations. In addition, the current key technology advancement efforts focus on improving handling and durability, as well as new practical technologies, such as inverter technology that is generated by regenerative braking, which is used to power the motor, or Charge the battery.
During the development of any part of the drive train, various electrical signals and physical parameters related to mechanical properties need to be measured and included as part of the complete test process. Electrical signals come from power circuits that link high voltage batteries and inverters, while physical parameters involve electrical to mechanical conversion processes. In order to thoroughly understand the performance of the entire system, it is necessary to measure the electromagnetic power converter and the power circuit and analyze the data from the powertrain management system operating on the automotive serial bus network such as CAN. In addition, these tests must be performed simultaneously to achieve an overall optimal solution, rather than optimizing a component individually.
The traditional approach is to measure electrical and physical parameters in a car using a data logger or data acquisition system with a sampling rate of up to 10,000 samples/second. Such systems typically have many channels that allow the user to combine multiple sensor outputs with isolated input channels to measure electrical parameters of the electrical system (often including floating voltage values) as well as temperature, vibration, and pressure on the material.
Car version ScopeCorder
Trends in electrical mobility development have led to the increasing use of power inverters, and because these devices support higher frequencies and higher voltages, there are isolated measurements up to 100 million samples per second (100 MS/s). Claim. These sample rates were previously implemented with an oscilloscope combined with a differential probe that allows engineers to observe transient voltages and currents at higher frequencies. A more interesting area is the drive management system, which operates on a serial bus such as a CAN network and continuously transmits engine performance parameters such as engine temperature, speed and pressure values. It is quite challenging to obtain electrical signals, physical performance parameters and data in the transmission management system through one measurement. To reduce the time and effort required to integrate these numerous parameter records, Yokogawa's DL850VScopeCorder automotive instrument combines the advantages of a high-speed oscilloscope with the advantages of a traditional data acquisition recorder in a single portable package. ScopeCorder captures and analyzes transient events that may last only a few milliseconds, as well as full driveline durability testing for up to 30 days.
Figure 1: A single measurement file created on the DL850V that integrates multiple high voltage and current signals, physical parameter measurements, and decoded CAN bus signals.
The latest automotive version of the DL850VScopeCorder instrument features channel isolation, signal conditioning and high channel count. It also provides CAN and LIN bus monitoring to help users decode CAN or LIN signals and monitor transmitted physical data such as engine temperature and wheels. Speed, acceleration and pressure. These values ​​are then compared to the data from the actual analog sensor. By combining multiple high voltage and current signals (sampled up to 100 MS/s) with physical parameter measurements (such as temperature, pressure or vibration and decoded CAN bus signals), the DL850V can create a single complete measurement file, see figure 1. This approach greatly reduces the time and effort required to analyze the entire system compared to other methods where measurement files from multiple measuring instruments must be integrated to perform analysis on a PC.
Power electronics in automotive applications
Inverters for automotive applications are increasingly using faster, higher voltage devices, which require isolated high-tolerance voltage measurement with higher sample rates and the ability to simultaneously simultaneously for longer periods of time Measure a larger number of signals. Traditional waveform measuring instruments like digital storage oscilloscopes have very limited capabilities for high voltage inverter measurements because they lack separate isolated inputs, high voltage isolation and 12 or 16 bit resolution. Other waveform measurement solutions typically require an external (active) signal conditioning circuit to achieve high voltage isolation.
The DL850ScopeCorder uses a technology called isoPRO in its high-voltage measurement module that provides 100MS/s sample rate, 1kV isolation and 12-bit resolution without the need for an external active signal conditioning device. The isoPRO technology uses a system that uses a semiconductor laser diode to convert digital data into an optical signal, and the converted optical data is transmitted to the instrument through an optical fiber. Since the semiconductor laser diode has a particularly high data transfer rate, a large amount of data can be transferred by a single device, so the isolation region can be made very small. In addition, because the fiber itself is insulated, the signal transmission distance along the fiber is sufficient to provide proper insulation, thus ensuring the insulation distance between the signal input and the main unit even at high voltages of 1 kV. With the isoPRO technology, two channels of 100MS/s, 1kV high withstand voltage isolation measurement circuits can be packaged in a compact module measuring approximately 100&TImes; 200mm.
Another benefit of this technology is that it provides excellent noise rejection. Because the switching speed of the high voltage inverter is very fast, noise is likely to be introduced into the measurement path. However, in high-voltage isolation modules, excellent noise suppression performance can bring good common mode rejection ratio (CMMR), and the floating voltage switching waveforms common to inverters and devices such as IGBTs can be accurately captured, as shown in Figure 2. .
Figure 2: Inverter signal pulse waveform measured using the DL850ScopeCorder module. On the left is the measurement with a sampling rate of 100 MS/s and on the right is the measurement obtained with the older 10 MS/s unit.
Mechanical/physical parameter value
The engine test rig is an instrument used to develop, characterize, test, and simulate a drive train. A complex engine test bench contains a variety of sensors (or inverters), data acquisition functions and actuators that can be used to control engine conditions. The DL850DscopeCorder has a modular structure and numerous input modules to monitor mechanical and electrical signals. The converter converts the signal from the engine into a form that the input module can understand - typically a voltage signal. For example, the engine speed in revolutions per minute is measured with a tachometer. This will generate a voltage output or a pulse output signal, then send this signal to the ScopeCorder for pulse output processing and display the actual acceleration pattern after the display - even extending the mechanical/electrical phase difference, see Figure 3.
Figure 3: Rotary encoder signal used to calculate the angle of rotation angle.
A thermocouple (usually a K-type device) can be used by using a temperature module. These thermocouples are inexpensive and good enough to perform tasks. Each input module can have up to 16 thermocouples connected to the instrument. To monitor the vibration of the drive train components, an acceleration module with a piezoelectric sensor can be used.
Car serial bus
The CAN or LIN network in the car is connected to the ECU (Electronic Control Unit), which transmits many parameters and control signals such as temperature, wheel speed, acceleration and pressure. The car serial bus and the ECU unit together form the drive train management system. This means that not only the electrical and mechanical signals from the analog sensors, but also the physical parameters transmitted on the serial bus of the car can be measured during development. They are also called electrical and analog sensor output parameters. The DL850V automotive version of the instrument decodes these CAN and LIN bus messages and displays both analog and electrical or mechanical signals on the screen. Figure 4 shows an example of this. This feature can be used to directly map the relationship between data transmitted on the car's serial bus and electrical and mechanical values, allowing real-time observation of system behavior. The DL850V supports CAN-dbc files (developed by vector groups) and LIN network definition files, allowing users to easily select CAN and LIN messages of interest.
Figure 4: The DL850 Automotive Edition instrument decodes these CAN and LIN bus messages and displays both analog and electrical or mechanical signals on the screen.
Summary of this article
The DL850VScopeCorder provides all the measurement and analysis tools of modern digital oscilloscopes, including cursors, waveform parameter calculations, math and DSP channels, and fast Fourier transforms. It also acts as a multi-channel data acquisition unit/recorder that integrates electrical, mechanical and automotive serial bus measurement functions in a single device. In most cases, users can analyze data and get results immediately, without the need for offline post-processing steps.
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Dongguan Andu Electronic Co., Ltd. , https://www.autoido.com