Starting from "Inverter spot check pass rate is less than 80%"

Konosuke Matsushita once said, "For product quality, it is either 100 points or 0 points." This sentence emphasizes the strict requirements for product quality. Usually, various words like "quality is the foundation" and "quality is the core" are often mentioned in the development of enterprises. Every enterprise manager and operator understands that quality is the basis of product sales. However, in actual production and sales, inferior products in various industries are still emerging in an endless stream, which seriously affects the healthy development of industries and sectors, and even endangers people's lives.

Recently, the General Administration of Quality Supervision, Inspection and Quarantine issued the "Announcement of the General Administration of Quality Supervision, Inspection and Quarantine on the Quality Status of National Supervision and Random Inspection of Products in 2015", which showed that the pass rate of random inspection of photovoltaic grid-connected inverters was less than 80%. It became a hot topic in the photovoltaic industry and once again focused the industry's attention on the quality of photovoltaic core equipment.

It is reported that this spot check was conducted based on the requirements of NB/T32004-2013 "Technical Specifications for Photovoltaic Grid-connected Inverters" and other standards, and 10 items of photovoltaic grid-connected inverter products were tested, including protection connection, rated input and output, noise, conversion efficiency, etc. The spot check found that 14 batches of products did not meet the requirements of the standards, involving rated input and output, harmonics and waveform distortion, power factor, DC component, over/under voltage protection items.

As a leader in the inverter industry, TBEA Xi'an Electric Technology Co., Ltd. has been committed to developing reliable and efficient inverters since its establishment. At present, its core products have obtained China's efficiency double A+ certification, with efficiencies as high as 98.52% and 98.63%, making it the most efficient company in China. "Our products are already so efficient, why do we still put reliability first? Because we know that if we want to be evergreen in the industry, product quality is the foundation. Only when the product can operate stably can the owner get benefits." said the inverter product manager of TBEA.

So, what is the quality improvement path of TBEA inverters?

First, excellent software design. Using the SVPWM modulation method with minimum switching loss, the IGBT loss is low, the stress is small, and the output current harmonics are small. Using the intelligent variable step multi-mode MPPT algorithm, the MPPT tracking efficiency is ensured to be no less than 99%. Advanced coordinate transformation control and stable and fast phase-locking algorithm are used under strong light conditions, and PR closed-loop control operation is used under weak light conditions to ensure that the grid-connected current THD is less than 3%. It can meet a variety of grid standards and set voltage and frequency protection thresholds according to grid requirements. In the case of severe voltage drop on the grid side, reactive power support is provided to facilitate successful low/zero voltage crossing.

Secondly, reliable hardware design. The core components of the inverter are all photovoltaic-specific components of well-known domestic and foreign brands to meet the product's design life of up to 25 years. Through reliability analysis of the product model, the product's average failure-free time can reach 100,000 hours. Sufficient margin is left when selecting inverter components to avoid failures caused by excessive voltage stress and current impact. The efficient heat dissipation design ensures that the inverter operates stably at a high temperature of 60°C; the intelligent heating system design makes the temperature difference between the inside and outside of the machine less than 3°C, and the inverter can operate normally at an extreme low temperature of -30°C. The use of high-quality centrifugal adjustable speed fans greatly reduces fan noise while ensuring stable heat dissipation performance; in addition, the introduction of reactors with leading potting technology can effectively reduce noise caused by air gaps and vibrations.

Third, strict quality process management. The quality control of TBEA inverter products adopts the approach of "prevention first, strict process control". During the R&D stage, multiple design reviews, DFMEA analysis methods, a dedicated testing team, and advanced testing equipment are used to test prototypes to ensure that potential product problems are resolved during the R&D stage. During the production stage, the company has established a complete product control process, including a supplier evaluation system, inspection control points at each stage, and complete operation guidance process documents. Monitoring is implemented at all stages from the source of the product to the shipment of the product, effectively ensuring the quality and consistency of the product. In terms of procurement, procurement operation specifications are established to effectively play the role of procurement and ensure that the purchased products meet the specified requirements. The raw and auxiliary materials of the product are delivered directly to the factory by the logistics company sent by the supplier. The procurement, warehouse, and quality inspection departments jointly receive the goods and are responsible for the quality inspection and reporting of the received goods...

With the proposal of "Made in China 2025" and the implementation of the "One Belt, One Road" policy, many Chinese inverter companies have set their sights on the global market. In this context, we should think more deeply about how to control product quality and what products can rely on to join the global competition. At the same time, as the industry leader, TBEA and other companies should shoulder greater responsibilities, actively drive and improve the level of industry development, firmly grasp the historical opportunities of the future photovoltaic market, and make Chinese photovoltaic brands stand out in the world.

With technology as the driving force and quality as the pursuit of development, China still has a long way to go in improving the quality of photovoltaic inverters.