High-speed HIL test platform for electric traction/electric propulsion systems

1 Introduction

The electric traction electric propulsion system with electric power as the propulsion power has the advantages of wide speed regulation range, large driving force, easy to reverse rotation, small volume, flexible layout, convenient installation, convenient maintenance, vibration and low noise. Therefore, in the power system The fields of torpedo electro-pushing systems, train traction systems, and hybrid vehicles have been widely used. These systems all adopt the complex main circuit topology of AC and DC, and also have the characteristics of high coupling degree, difficult to simulate load, and high control difficulty. Therefore, higher requirements are put forward for its test and verification methods.

The traditional HIL simulation technology usually runs the controlled object model directly in the processor of the real-time simulator. However, due to the real-time operating system constraints, the step size can only be on the order of 10us, but it is used, for example, in the field. When the 6-phase or 12-phase motor is used for semi-physical HIL simulation, the simulation step size is required to be no more than 1us. In this case, if the traditional HIL simulation technology is used, the real-time simulation of the high dynamic electrical controlled object cannot be met, and the simulation divergence may occur. Distortion, phase angle calculation error, and reduced simulation accuracy. Therefore, Hengrun Technology has launched a high-speed dynamic HIL test based on the high-speed FPGA electric power system HIL dynamic test solution to achieve 100ns simulation step size. And it has been successfully applied in the domestic rail industry. At present, the only three train test systems for whole vehicle traction systems in China are constructed by Hengrun Technology.

2. System solution

The high-speed HIL test platform based on FPGA, the system composition is as shown below:

Figure 1. High-speed HIL test platform system composition

The system mainly includes the following subsystems:

1) Real-time simulation system: real-time solution of complex main circuit model (based on FPGA real-time simulation technology), carrier (train, vehicle, etc.) dynamics, and control loop through the IO interface and the controller under test.

2) Fault injection system: implement fault injection of physical layer, electrical layer, protocol layer, etc.

3) High-speed signal conditioning and adaptation system: to achieve signal conditioning and adaptation.

4) 3D Vision System: Shows the system running status in the form of 3D view.

5) High-speed data acquisition system: realize multi-channel high-speed signal acquisition, storage, playback, analysis and other functions.

6) Laboratory management software: to achieve laboratory-level platform management, including test control, automated testing, test data management, test requirements management and other functions.

3. Key technologies

In the HIL test platform for electric traction electric propulsion, the focus is on how to build a test and verification environment including high-speed FPGA simulation, high-speed data acquisition, and high-speed conditioning to achieve high-precision, high-dynamic real-time simulation and ensure the quality of data transmission and storage. . Key technologies include:

• Complex electrical main circuit modeling based on System Generator

System Generator is a design tool developed by Xilinx for digital signal processing. It can be built directly in the simulink environment, and then through the HAC technology provided by Hengrun Technology, the model can be directly compiled and downloaded by automatic code generation. In the FPGA.

In the electric traction network and electric propulsion system, most of the main circuits are AC-DC-AC, DC-AC and other topologies. The middle involves transformer model, pre-charging model, rectification model, intermediate circuit model, chopping model, and inverse Variable model, motor model, single-phase full-wave uncontrollable rectification and other models, and how to accurately build these controlled object models, how to build the above-mentioned sub-model into a complete main circuit model becomes the core of the HIL test platform. Take the auxiliary system model in a cooperative project as an example:

Figure 2. Traction-assisted main circuit and its subsystem model in a project

As can be seen from the above figure, the main circuit topology of such an electric power system is extremely complicated. The subsystem modeling method is generally adopted, and then the subsystem model is integrated to form a complete main circuit topology model. The characteristics and working principle of the circuit must be fully considered in the modeling, and the system is described in mathematical language. The process involves transfer analysis. Discrete, fixed-point and other key steps, in addition to the main circuit model is not directly built into the subsystem, may need to consider whether to add inertia, whether to add damping factor, etc., also need to consider FPGA timing, pipeline design. Hengrun Technology has practical applications in many implementation projects. It is rich in rich modeling and can be modeled for customer specific application scenarios.

• High speed FPGA emulation products

In order to meet the high-speed and high-dynamic electrical object simulation, Hengrun Technology has independently researched two FPGA-based solutions. One of them is the HR-cPCI-5125 FPGA emulation board, which uses Xilinx's K7 system processor and has multiple AD, DA, DIO, and resolver interfaces. It can be installed in cPCIa or PXI chassis. The other is the HAC5161 FPGA emulation device, which adopts 1U standard upper cabinet structure, has rich FPGA resources, and can be extended by 6 IO daughter cards, enabling up to 384 DIO or 96 AD and DA channels.

Figure 3. High-speed FPGA emulation board and device

• High-speed data acquisition technology

In the HIL test platform, the management of experimental data is also crucial. Data analysis is the purpose of the experiment. In order to collect the data in the storage experiment and retain the experimental details as much as possible, Hengrun Technology has developed a high-speed data acquisition system called Lighting Tracker ("LT"), which can collect up to 1M Samples/S. Hundreds of high-speed signals are stored and can be:

1) Hardware resource management

2) Real-time waveform display

3) Historical data management

4) Data analysis

Figure 4. High-speed data acquisition software interface

• High-speed signal conditioning technology

The signal conditioning system is used to adjust the input and output signals of the TCU to the input level of the simulator. In the systems of electric traction and electric propulsion, there are many types of conditioning systems, including voltage signals of different levels, various range of current signals and fiber signals, and high-speed signal changes, reaching microsecond response. Signal conditioning systems are much more difficult to design than others. The typical indicators that Hengrun Technology can achieve in high-speed signal conditioning systems in many implementation projects are as follows: isolation, delay time <2us, frequency >1kHz, drive capability >10mA. Analog signal accuracy <1%, bandwidth >20kHz, linearity <1%, etc.

Figure 5. Physical map of high-speed signal conditioning system

4. High-speed dynamic test verification solution to bring benefits to customers

♦ It can simulate the extreme working condition fault condition test which is difficult to carry out in the physical test to avoid damage to the actual system.

♦ It can realize long-time simulation for several hours, avoiding the phenomenon that the simulation software crashes due to insufficient memory.

♦ High simulation efficiency: offline simulation (such as offline simulation based on simulink) can take 10 minutes or even 1 hour in 1 minute; only 1 minute in real-time simulation

♦ It can simulate various fault injections (including motor phase loss, sensor faults, etc.), and can fully test various control logics of the verification control system to ensure the correctness of the development system.

♦ It can be used as a debugging platform developed by the previous controller to provide a virtual controlled object environment, improve the development efficiency of the control law design and debugging improvement process.

♦ High-speed dynamic simulation test platform can improve simulation accuracy

♦ High-speed data acquisition system, which can completely store test data, facilitate data analysis and troubleshooting after test

5. Application & Case

• Traction system development test platform for a rail transit unit

The traction system development test platform provides support for debugging, function and performance testing of the traction control unit, providing dynamic display including debug/test virtual environment, test status and effects, and laboratory-level automation control. The function of the semi-physical simulation platform using the traction system is as follows:

♦ Realization of 4 moving 4 tow EMU simulation test

♦ Realize 4 track 2 tow urban rail simulation test

♦ High-speed simulation of traction main circuit and auxiliary main circuit by FPGA, the simulation step is up to 100ns

♦ The system has more than 10 cabinets and more than 10,000 lines, which are characterized by high complexity.

♦ High-speed data acquisition system capable of high-speed acquisition of 32 analog and 80 DIO

Figure 6. Composition of a semi-physical simulation system for a railroad unit

As a leading electronic system supplier in China, Hengrun Technology provides high-precision servo control technology, high-power converter technology, complex electro-hydraulic system modeling technology, and high-performance real-time simulation technology to provide electrical, electromechanical and power system development. Test and verify environments and other advanced solutions. In the simulation test field of the above three systems, we have rich engineering experience to provide users with high quality products and services. Among them, power level HIL, complex traction control system test, power supply and distribution system test and other solutions have Leading technology; winning the unanimous recognition of customers and contributing to the development of the cause.