Industrial digital dependence, who drives "Industry 4.0

Technological progress and rising labor costs have jointly promoted the upgrading of industrial manufacturing. Globally developed manufacturing regions have formulated corresponding development plans, such as “Made in China 2025”, “Industry 4.0” and “Industrial Internet”.

In the process of digitization and intelligentization of industrial production, we should not forget the semiconductor components that really "drive" the operation of industrial equipment, especially power devices. Today, power devices are widely used in various industrial devices to control, convert and regulate system voltage and current, from MOSFETs, IGBTs, to emerging silicon carbide (SiC) and gallium nitride (GaN) devices, different types. The power devices meet the needs of different industrial application environments.

Industrial Application Requirements for Power Devices

Power devices for industrial equipment are used under harsh conditions. Some applications require 24 hours and 365 days of uninterrupted operation. Reiko Kokihiko, Senior Division Specialist at Renesas Electronics Greater China Automotive Electronics Business Center, points out that two points must be considered when designing and developing power devices. "One is the loss characteristics. Because of the non-stop operation requirements, how to reduce the losses generated by the device has a direct impact on the plant's electricity bill. Moreover, different applications require different switching frequencies. Engineers need to determine the limited consideration in accordance with the actual switching frequency requirements. Loss or switching loss, and then determine the best choice; second is the reliability, especially in unmanned factories, device failure will directly affect the loss caused by the operation of the plant, so device tolerance is also a priority consideration."

“Industrial equipment and automated production lines have absolute dependence on power devices. These devices use power devices to achieve energy conversion. The realization of functional actions is also achieved through the control of power devices.” Du Yusheng, manager of application technology at Littelfuse, believes that The increasing demand for power devices, high efficiency, low power consumption, small size, and ease of control and ease of application are all requirements for power devices in industrial applications.

“Power devices used in the industry must be reliable, efficient, compact, able to withstand load dumps, and maintain output stability over a wide input voltage range,” said Jon Gladish, applications engineering manager at ON Semiconductor. “In addition, power conversion losses Be small and able to work over a wide temperature range."

High power devices

High-power devices are mainly used in industrial applications. Compared with low-power devices, there are more factors that need to be considered in the design, development, and application of high-voltage, high-current, high-power devices.

"High-voltage and high-voltage products must consider the stress design problem, and high-power devices are usually not an ideal switching device, so we must pay full attention to conduction loss, voltage change rate (du/dt), and current change rate ( Di/dt) and other issues, diode reverse recovery time also need to be considered.” Ritter Du Sheng said that the power device voltage setting is also very important, coolMOS voltage is now close to the limit to 1200V, 1700V and 3300V can only use IGBT, but Ritt's Silicon Carbide (SiC) MOSFETs are very easy to implement with minimum voltage designs of 1200V and 1700V.

Of course, the silicon carbide MOSFET gate drive is a design difficulty, because the silicon carbide device itself is small loss, the switching frequency can be designed to 500KHz level, so the drive signal will be very fast, in addition to power isolation, but also do a good job of signal insulation isolation. High-frequency signals also bring about electromagnetic interference problems. “Anti-jamming and interference suppression will become headaches. Engineers must face EMI problems, or they will trigger false triggers to cause the device to lose control. High-frequency optimization of circuit boards and design of multi-point grounding systems It also becomes a difficult point. System design must not only perform time domain analysis but also perform frequency domain analysis."

ON Semiconductor Jon Gladish emphasized that safety is always a major consideration in power device applications, especially for high-voltage, high-current, high-power devices. "UL believes that if a voltage higher than 60V comes into contact with the human body, it will cause injury and even cause death. Therefore, when high-power devices are used, safety design must be fully considered, and creepage distances and clearance requirements must be met to ensure safe application of high voltage devices. The primary condition for this is that dust and foreign matter around the high-voltage pins are also hazardous, and functional defects must be investigated.

Since high-power devices generate a large amount of heat during operation, special attention must be paid to their thermal design to minimize the mechanical stress caused by thermal expansion mismatch to avoid danger. JonGladish mentioned several points on how to design heat dissipation: compliance with the PCB layout (wire width, thickness, and diameter of the PCB must be taken into consideration), excellent heat dissipation architecture, and smaller thermal resistance packaging materials.

Renesas Electronic Co., Ltd. said that in high-voltage and high-current applications, it is not always a single chip that can handle large currents. For two or more chips used in parallel, the most important thing is to control the characteristic deviation among multiple chips. "The deviation of the chip characteristics will cause current deviation, and the current-concentrated chip will be in a state of overheating or even damage, so controlling the manufacturing process deviation of the device is very critical."

Common failure modes

Power device failures often have more serious consequences. Especially in industrial applications such as uninterruptible power supplies, solar inverters, telecommunications, and charging piles, if a power device fails during operation of the device, it may cause multiple secondary failures such as melting, fire, or explosion. “So usually, industrial systems have over-voltage protection (OVP) over-current protection (OCP) and other fault detection functions,” JonGladish said, relying on the fault detection function, power device failure occurs, the system can cut off power in time to avoid Secondary failure.

Jon Gladish summarized five common power device failure modes: avalanche breakdown; electrostatic discharge (ESD) or gate surge; and body diode reverse recovery current is too large. Parasitic BJTs may be triggered; long-term operation in the linear region, thermal runaway due to excessive current, and package damage due to improper assembly.

Ochiai Kang Yan believes that according to statistics of Renesas Electronics, more than 90% of customer's failure problems are caused by over-voltage or over-current damage, especially in switching devices such as IGBTs and MOSFETs, and many failures occur in the switching process. "To prevent such failures, use appropriate driving conditions and try to suppress PCB parasitic inductance."

"The most common failure of devices is voltage breakdown, short circuit burnout, so the device must be strong against surges, must have strong impact resistance, and must also have high voltage withstand capability. Short-circuit failures make us the most troublesome problem because The short circuit of the device will have the biggest sandal victory for the power supply, which may burn the entire circuit board or even cause a fire." Du Fusheng gave an example. The frequency converter in the factory is usually operated in six sequential stages. If the device fails, it will trigger the upper and lower bridges. Short circuit, unprotected tubes will blow up. "Short-circuit protection of power devices is a very important design aspect. The driver board will set the short-circuit protection time, and the power devices will also have the maximum short-circuit current rating."

Power Device Development Trend

Digital chips that follow Moore's Law are very fast, compared to the slow development of power devices, but they are also evolving, from the earliest thyristor technology to GTO technology, MOSFET technology, to IGBTs, IGCTs, or IGETs. Silicon-based technologies seem to have reached their limits on operating voltage and losses. "The rise and maturation of SiC technology has brought a dawn of revolution to power devices," Du said. Increasing power density is a major requirement for current power device technology. Both the power transmission system and the power conversion system require high energy efficiency ratios. Ritt's SiC products have reduced the loss by 80% compared to conventional power devices and have almost become an ideal switching device."

In addition to traditional IGBTs, ON Semiconductor continues to develop wide band gap device technologies, including silicon carbide (SiC) and gallium nitride (GaN). In addition, superjunction and shielded-gate silicon-based MOSFETs are also key inputs. direction. "The industry trend is to design faster devices with lower on-resistance, and continue to reduce silicon characteristic on-resistance (RSP) and switching losses to achieve higher energy efficiency and power density." JonGladish pointed out that there is also an optimization The direction is a new type of package. The focus of ON Semiconductor's focus is on surface-mount packages with low parasitic resistance and inductance, as well as packages that enhance heat dissipation, such as double-sided cooling packages.

Jon Gladish summarized power technology trends in four directions. The first is high pressure, the trend of high pressure is to improve energy efficiency; the second is modularization, and the higher rated power is achieved through more effective thermal management; the third is advanced technology research and development, focusing on silicon technology and wide band gap (SiC). Power device technology for materials such as GaN, etc.; and finally smart, smart power devices with protection functions will be more suitable for industrial control.

Intelligent

According to Jon Gladish, although intelligent power modules (IPMs) are more advanced than ordinary discrete devices and are more optimized for specific applications, users are not necessarily buying because smart power modules are usually more expensive and not like discrete devices. Standardized products.

However, the advantages of smart power modules are more. Firstly, the module has better performance, higher isolation, and better heat dissipation. At the same time, the module can also contain complete protection functions such as over-voltage, under-current, and thermal shutdown. Secondly, using the module can reduce the system size. The power module is usually packaged in a systematic manner, and the dies, IGBTs, diodes, and driver circuits (GDUs) are all enclosed in a single package, thereby saving system space. Finally, the module has higher reliability and intelligent power modules. The group has a smaller number of components, a reduced number of processing steps, better protection measures, and better heat dissipation, which all mean higher reliability and longer life.

Renesas Electronics Co., Ltd. said that the use of IPM and other power devices in the air conditioning is already very extensive, but industrial high-power devices are usually used in parallel with multiple chips, so the intelligence is the intelligence of the entire device. "For example, using IGBTs in pure electric vehicles, Renesas Electronics' idea is not to make the IGBT itself intelligent, but to provide customers with the entire intelligent inverter solution including IGBTs."

"Intelligent products integrated with drive management, thermal management and protection management will make the engineering design more concise. The products of Lite will be more flexible and easy to use. It will also bring about changes to the entire industrial application. Industry 4.0 is also intelligent manufacturing. The process, this process is inseparable from the intelligent power devices or modules.” Equipment informatization is the basis for the realization of Industry 4.0, as Du Yongsheng said, intelligence is the development trend of the power device industry.

to sum up

Power devices are the core devices that ensure the normal operation of industrial equipment. The harsh industrial application scenarios impose higher requirements on the parameters of industrial power devices, and need to add a variety of protection measures to prevent disasters caused by the failure of power devices. High voltage, modularization, and intelligence will be the main trends in the development of power devices in the future, and wide bandgap semiconductor technology is also receiving more and more attention. It can be foreseen that the acceptance of intelligent power modules will become higher and higher during the implementation of Industry 4.0.

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