Technology Trends

AC-DC Converter IC Incorporating 1700 V SiC MOSFET Supports Further Moves Toward ”Smarter” Plants

2025.01.20

Points of this article

・Accompanying moves toward “smarter” production lines in plants, there has been an accelerating trend toward introducing advanced information communication equipment alongside equipment and facilities on production lines.

・An AC-DC converter IC incorporating a 1700 V SiC MOSFET can help ease the way for high-efficiency auxiliary power supplies that convert high-voltage power for industrial applications to power suitable for communication equipment.

Movement Toward Smarter Production Lines Accelerating in All Industries

At manufacturing plants in all industries, ranging from automobiles and semiconductors to food products, pharmaceuticals and cosmetics, there are simultaneous demands for both productivity and quality improvements, and for decarbonization (lower power consumption and reduction of greenhouse gas emissions).

In manufacturing industries in the past, the greatest emphasis was placed on boosting productivity and improving quality in a plant. But in recent years, contributions made to decarbonization have become a factor affecting the perceived contribution of a company to society, and the introduction of carbon pricing has become a new condition for entry into a market.

However, improving productivity and quality of production lines while simultaneously moving toward decarbonization is not easy. In order to address such new demands of this era, there have been movements to introduce “smarter” production management systems at many plants (Figure 1). In such systems, sensors are installed on line equipment and devices, various kinds of data are collected, and device and equipment operation as well as the states of products are made visible. Moreover, in these systems artificial intelligence (AI) and “big data” analysis are also utilized to optimize process conditions in realtime.

Figure 1. “Smarter” production lines to improve productivity and quality while contributing to decarbonization

Figure 1. “Smarter” production lines to improve productivity and quality
while contributing to decarbonization

The Means of Supplying Power is One Problem when Installing Communication Equipment in a Plant

In order to construct a smart production line, various information and communication devices and controllers, such as IoT devices, edge computers, and network equipment, must be installed on the production line in greater quantities than what was used in the past. In general, various devices relating to production are positioned densely on the floor of the plant. When making a plant “smart”, however, searching for gaps in such preexisting layouts and figuring out how to insert large numbers of additional auxiliary units for communication becomes a major headache. Amidst all this, one vexing problem is finding the means for efficient supply of power to auxiliary devices when the latter are positioned in a distributed arrangement.

If wireless devices are used in an information network within the plant to exchange data acquired by sensors, there is no need to lay cables. However, this is not true of power supply lines. In general, the large-output motors and heaters used in manufacturing equipment are driven using AC (alternating current) power of at least 200 V, and in many cases 400 V. But because auxiliary equipment that use semiconductors as core components typically use DC (direct current) power at from 5 V to 48 V, it becomes necessary to provide a power supply separate from those already installed for use with the manufacturing equipment and devices.

Requirements Demanded of AC-DC Converters to Support “Smarter” Lines

The simplest way to introduce power supplies for auxiliary equipment is to draw power from an existing power supply line, such as an AC 400 V line, and use an AC-DC converter to convert this to DC 5 V to 48 V (Figure 2). However, auxiliary equipment for data communication is necessarily subsidiary equipment, and so an AC-DC converter to be used as an auxiliary power supply must meet the following engineering requirements so as not to disrupt the equipment and facility layout within the plant or lead to increased power consumption.

Application Example
New product solutions for 400V AC class industrial equipment

Figure 2. Utilization of AC-DC converters in power supplies for auxiliary equipment,
and requirements made of them

To begin with, such converters must be compact. It would be ideal for the power device, driver IC, and other semiconductors constituting the AC-DC converter could be integrated in a single package. There are also demands that coils, capacitors, and other components of such converters be miniaturized by raising the operating frequency of the AC-DC converter, and that heat dissipation mechanisms be reduced in size through the use of low-loss, heat-resistant power devices.

Next, high reliability is required. Equipment on production lines is used under harsh conditions, and moreover economic losses in the event of a malfunction are huge. Reduced risk of component malfunction through a single-package design, as well as the introduction of various protection functions, will be absolutely essential.

Finally, such converters must have high efficiencies and low losses. And, as a means of achieving decarbonization, production lines are made “smarter”; so if the auxiliary power supplies used for this purpose consume large amounts of power, the original objective is defeated. Among industrial equipment, there are some systems which are already provided with auxiliary power supplies to drive control equipment. However, in many cases, these use power devices which have low voltage ratings or large losses, and so, contrary to expectations, large amounts of power are consumed. Hereafter, power devices optimized for handling AC power at voltages of 400 V and above will become indispensable.

Significance of Use of SiC-MOSFETs in AC-DC Converters and Associated Problems

Novel semiconductor technologies making possible dramatic improvements in efficiency and reductions in size are being applied to AC/DC converters and all kinds of other power conversion circuitry. In these power devices, silicon carbide (SiC) has come to replace the previous standard Si as the material used as the semiconductor substrate.

By adopting heat-resistant SiC MOSFETs with their low conduction losses and switching losses as the switches in power conversion circuits, high-output AC-DC converts that do not require a heat sink become possible. Moreover, high-frequency driving also becomes possible. And if SiC-based power devices are exploited, many of the technical requirements sought from AC-DC converters for use in “smart” factories can be satisfied.

However, in order to maximize the excellent latent performance of SiC MOSFETs, they must be combined with driver ICs with specs optimized for driving them. Existing driver ICs are optimized for the characteristics of Si-based power devices, and cannot be employed with SiC devices as-is.

Superior Performance and Advantages of Adoption of ROHM AC-DC Converters with Internal SiC MOSFETs

ROHM has developed the BM2SC12ｘFP2-LBZ AC-DC converter IC incorporating a 1700 V SiC MOSFET. The new product is being provided for applications in auxiliary power supplies. This is the world’s first product in which a high-voltage MOSFET rated at 1200 V or higher and a gate driver IC are sealed in a single package. The twelve separate chips constituting an ordinary AC-DC converter utilizing a Si MOSFET have been consolidated in a single package, achieving a dramatic reduction in the number of components (Figure 3).

Application Circuit and Adoption Results

Si vs SiC Efficiency Comparison in an AC/DC Converter

Figure 3. Twelve components of an AC-DC converter for auxiliary power supplies
consolidated in a single package

Moreover, customers can now develop highly efficient, compact AC-DC converters in the fewest man-hours possible and while securing high reliability. In addition, by incorporating SiC MOSFETs, it is also possible to implement high-precision overheat protection and overload protection (FB OLP) functions, overvoltage protection (VCC OVP) at the power supply voltage terminal, overcurrent protection, and overvoltage protection of the secondary-side voltage. In these ways, reliability has been enhanced so as to enable application in auxiliary equipment of production systems, for which continuous operation is mandatory.

Moreover, ROHM has utilized extensive technical insights relating to SiC MOSFETs to optimize the specifications of gate driver ICs for auxiliary power supplies for use with manufacturing equipment. The power conversion efficiency of AC-DC converters has been boosted dramatically, from 78.5% when using silicon MOSFETs to 83.5%. Control circuits adopt a quasi-resonant design, which makes possible lower-noise, higher-efficiency operation compared with the more general PWM design; hence the effect of noise on manufacturing equipment can be held to a minimum.

ROHM’s BM2SC12ｘFP2-LBZ aims at improvement of productivity and quality together with decarbonization, and can be said to be a highly effective device that will be indispensable for the construction of smart production lines.