Platform-based power supply testing and application

Testing is an essential part of ensuring product quality. Manufacturers need more accurate, flexible and economical testing systems. The faster the industry develops and the more widely used the products are, the stricter and more varied the requirements for testing and related technologies will be, just like the huge challenges of testing work brought about by the rapid development of the power supply industry.

Actual demand drives continuous improvement in power supply testing

Power supplies are everywhere in our lives. From consumer electronics to military equipment and industrial facilities, many electronic devices require power supplies to ensure normal operation. In principle, common examples of power supplies include AC-DC switching power supplies and DC-DC switching power supplies for communications. In addition to the above two categories, special power supplies for specific applications are also common. Regardless of the type of power supply, its testing process is a huge challenge, mainly focusing on the following aspects.

1. Continuous improvement of indicators and functions

1) The topology of power supply is becoming more and more complex: the development of switching power supply technology has evolved from the original three basic topologies to the current multiple structures. The complexity of the topology and the development of auxiliary technologies such as soft switching have increased the number of circuit nodes and control signals. Therefore, in the design process of the power supply, it is particularly important to accurately collect the status of each node and control signal of the circuit. For example: the synchronous rectification power supply needs to synchronously monitor the control signals of several switches; the flyback power supply needs to simultaneously monitor the current status of the two isolated current paths of the primary and secondary.

2) The efficiency requirements of power supply are getting higher and higher: With the continuous innovation of microprocessor technology, its power supply is also developing in the direction of low voltage, high current and high power. In addition, the miniaturization of power supply equipment has higher requirements for power supply efficiency. Generally speaking, the loss of switching power supply mainly comes from switching loss and inductor magnetic loss. Therefore, in the research and development process, measuring the energy consumption of these two aspects will become another important requirement.

3) The importance of transient characteristics of power supplies is gradually increasing: In order to better test the power supply, process indicators such as opening time, closing time, and DC output stabilization time also need to be accurately tested. This requires the test equipment to have higher accuracy and bandwidth while comprehensively using test-related technologies to accurately capture these signals.

2. Reduce costs and accelerate updates and iterations

With the rapid development of related technologies, the replacement of electronic equipment has accelerated, which has made the update cycle of power supply product models shorter and shorter. The development of power supply technology itself has also accelerated the update and iteration of power supply products. The time required for new products to complete the testing work is getting shorter and shorter. Power supply manufacturers urgently need the test system to have functions such as fast model change, seamless migration of test sequences, and system self-learning, so as to truly realize the co-line testing and co-platform testing of different models of products. Although the time left for design engineers to design, produce and test is getting shorter and shorter, the cost of products is decreasing. According to an authoritative survey data, the average cost of AC/DC front-end switching power supplies has dropped from 0.1 to 0.2 US dollars per watt in 2003 to 0.08 to 0.14 US dollars per watt, but the test indicators are becoming more and more stringent, and cost reduction has become one of the focuses of concern for enterprises. The modular and open test system can reduce the test cost and quickly adapt to different objects under test, which makes up for the shortcomings of traditional desktop test equipment and is more suitable for current power supply testing needs.

[page]3. Urgent need to master core technologies independently

Every company is eager to master its own core technology, which is the core competitiveness on which the company relies for survival. The same is true for companies that develop and produce power supplies. In the process of transformation from Made in China to Created in China, more and more power supply manufacturers continue to accumulate and improve their core technology strength, laying a solid foundation for producing competitive products in the global market. The final inspection test in the product production link can no longer meet the current testing needs. Power supply manufacturers expect the test system to provide strong support in the entire process of research and development, design and production. Accordingly, how to help companies master core technologies is also a goal and challenge facing test and measurement manufacturers.

Figure 1: Power MASTER power supply test kit.

Platform-based power supply test solution

Based on the above challenges, it is not difficult to see that power supply manufacturers need a convenient and fast power supply testing and detection platform on the one hand to improve the ease of operation and maintenance of power supply product testing, reduce maintenance and testing costs, etc. On the other hand, they also need efficient, high-precision, and high-reliability testing systems to launch better new products as soon as possible and win business opportunities. Therefore, neither the initial manual workshop operation method nor the traditional desktop instrument method can meet the current testing needs. Combining the experience of domestic and foreign technologies and a large number of practical applications, it can be seen that platform-based power supply testing can help us solve these problems.

1. Modular hardware platform

In order to ensure reliability and obtain maximum flexibility, the test system often requires a unified hardware platform, including core data acquisition equipment, test environment provision equipment, signal access and fixtures, matrix and routing, etc. Each part can provide mature and complete optional combinations to quickly meet different test needs and different application scenarios.

The choice of the core test platform plays a vital role in the flexibility of the hardware platform. As the mainstream test bus, the PXI bus has a modular hardware architecture that can provide flexible and diverse hardware combinations, covering programmable AC/DC power supplies, electronic loads, digital meters, oscilloscopes, timing/noise analyzers, short-circuit and overvoltage protection testers and other equipment, thereby truly meeting the basic electrical function test requirements of any form of power supply in terms of hardware.

2. Highly integrated intelligent software platform

Software plays an important role in platform testing. It must be easy to use and user-friendly, and accurately interact with all hardware in the platform. More importantly, it must have functions such as intelligent resource allocation/interaction perception. Specifically, power supply test software should have the following features:

Customizable: supports free editing of test items for different power supply models, optimizes test command technology for execution efficiency; Scalability: convenient to add new test items and functions, open test ports, seamlessly link hardware platforms, suitable for self-developed testing of various power supplies; High reliability: the development process introduces a reliable guarantee mechanism from downstream to upstream, the program code has been fully tested, the development process follows relevant standards, has good robustness and fault tolerance, can ensure the reliability of the power supply test system in software design, and the hardware connection part has been tested on multiple platforms to ensure performance during use; Strong professionalism: Functional optimization for power supply test applications, with relevant bus communication capabilities, automatic generation of reports according to test requirements, with database operation capabilities, convenient for quality statistics.

3. Test application case: onboard secondary power supply test

The system tests the power supply of the satellite control subsystem, which belongs to DC testing. It can test 12 types of satellite-borne secondary power supplies on a unified platform and analyze their voltage characteristics, power characteristics, and load characteristics. It has good scalability and can form a system with peripheral equipment such as oscilloscopes and primary power supplies. It has good scalability and can test new types of power supplies and adapt to satellite-borne environmental requirements.

[page]4.Test application case: Server power supply automatic test bench

It has the functions of parallel test instrument control, custom editing of test sequences, configuration of report generation specifications, etc.; it can easily realize the test of basic electrical functions of various power supplies. The main test items: the reaction characteristics of output under dynamic load (Dynamic Response), the stability of a certain output voltage when the input power changes (Line Regulation), the timing of each group of output voltage rise when starting (Turn on Time), overvoltage protection test (Over Voltage Protection Test) and other power characteristics, time characteristics, and electrical characteristics. It supports all standard commands and extended commands of PMBus1.1 version, is compatible with custom instructions, supports manufacturer-defined command code tables, supports flexible configuration and addressing of 7-bit and 10-bit device addresses, and the communication rate is up to 400Kbps. It includes comprehensive function modules, which is convenient and practical.

How to obtain real test requirements

Being user-oriented is a major feature of the development of the test and measurement industry. Meeting customer needs or even ahead of them is what testing manufacturers need to keep in mind at all times. The trend of segmentation of test and measurement needs is the mainstream trend. Different industries, different regions, different manufacturers and even different product lines have different needs. In the field of mid-to-high-end power supply testing dominated by foreign companies, Beijing Panhua Hengxing Technology Co., Ltd. has its own unique series of specifications and methods for how test systems can keep up with the development of the power supply industry and how to conduct tests according to local conditions.

1. Fully automated testing and flexible and easy debugging

Due to factors such as labor costs, training costs, and human error, the final inspection test of the production line hopes to increase the degree of automation as much as possible. However, since the product has not yet been finalized, the test equipment required in the research and experimental stage needs to be modified and debugged a lot, so researchers hope that the test equipment can be as flexible and open as possible to facilitate testing during the R&D and design process.

2. High precision and strict test rhythm

During the experimental research and development stage, the requirements for test accuracy are often higher than those for production stage testing after the product is finalized. However, the test rhythm requirements in the production stage are extremely demanding. In many cases, even a fully automated test system cannot meet the test rhythm requirements of the entire production line. At this time, it is necessary to adopt parallel testing technology according to local conditions to improve test efficiency.

3. Differences in test environments

The test environment in the laboratory is relatively ideal, but in actual engineering applications, the test environment becomes much more complicated. In order to ensure the accuracy and indicators of the test system, it is necessary to consider the impact of environmental factors when designing the test system.

4. Differences in software requirements

Research software and production software have different application stages, so there are great differences in requirements. Research software is used in the technology research and development stage. Because the technology and products have not yet been finalized, there are more variables, and the software needs to be constantly changed according to the continuous formation of technology. Therefore, research software requires a flexible and robust architecture that can quickly respond to and meet the needs of various changes, while the requirements for ease of operation, stability and functional integrity are relatively low. Production software is used in the stage where technology has been transformed into productivity, that is, the production stage of the product. Since the product has been finalized, the software needs to be complete and easy to use, and the software needs to be stable to ensure the smooth progress of production.

Conclusion

The platform-based power supply test mode has been fully verified by a large number of actual power supply test projects and can meet the actual needs of power supply testing. The flexible combination of platform-based architecture and modules can adapt to the testing of different application occasions, different stages, and different product models to the greatest extent. The highly centralized intelligent software support makes the process faster and more convenient, which can provide strong guarantee for the smooth development of power supply research and development and production, and is undoubtedly the future development trend of power supply testing.