Servo Drive

Preface – Servo Drive –

Akira Kumagae

Corporate Vice President
General Manager of Motion Control Division
Akira Kumagae

AC servo drives have been adopted in many different production sectors, including on robots, machine tools, semiconductor manufacturing equipment, electronic part mounting apparatus, presses, and textile machinery. These servo drives have become an extremely important product that affect the productivity and manufacturing quality of the customer’s equipment. In recent years in particular, in addition to business for smartphones and automobiles, business is also prospering in areas such as data center investment, where the IoT (Internet of Things) is frequently used as a keyword, and the demand for servo drives is continuing to expand, especially for machine tools, semiconductors, and electronic component related business. Furthermore, there is a global trend towards the realization of smart factories, as represented by the “Industrie 4.0” initiative in Germany and the “Industrial Internet” in the U.S. As AC servo drives are a key component of automation technology, it is expected that demand for them will increase even further from now on.

As a result of these major changes that are occurring in manufacturing industry, there is also a great shift occurring in the requirements for AC servo drives. The previous requirements for high speed movement and accurate stopping at the position decided are now quality requirements that are taken for granted as the original performance of servo drives. On top of this, it is becoming necessary to offer miniaturization and the expansion of lineup to be able to respond to various machine applications. In the requirements for smart factories in particular, new requirements for AC servo drives that are becoming more prominent include the mounting of high speed networks based on general purpose LAN and the reinforcement of information transparency.

Yaskawa began selling DC servo drives in 1962 and AC servo drives in 1983. The Σ series of all-digital AC servo drives was launched in 1992. This series realized great miniaturization and performance improvements and the digitization further improved the ease of use. AC servo drives had previously only been used in a limited number of applications such as on machine tools, but the Σ series greatly expanded their possibilities. Since that time, we have proceeded with further miniaturization, performance improvements, and the expansion of the lineup to suit the market requirements and this has led to the successive generations of the Σ-II, Σ-III, Σ-V, and Σ-7 products. In April 2017, the cumulative total of Yaskawa AC servomotor units shipped reached 15 million.

The Σ-7 series that currently forms our main line of products was developed with the concept of “seven ultimates.” We supply the optimal products to the customers based on the seven key phrases of “system performance,” “ease of use,” “environmental performance,” “safety and security,” “support,” “lineup,” and “compatibility” and the series has been very favorably received since its release in 2013. The Σ-7 series continues to evolve as we release new products in the “Σ-7 family,” including the “batteryless absolute encoder” that does not require a battery for data storage and the “integrated servomotor” that combines a servo amplifier with a servomotor in one unit and simplifies control panel design. The integrated servomotor achieved particularly great miniaturization by being the first in the world to adopt gallium nitride (GaN) power semiconductors to realize high speed switching that could not be achieved with silicon (Si) power semiconductors. There are great expectations for this from now on as a product that demonstrates new possibilities for AC servo drives.

This feature gives an outline description of the initiatives at Yaskawa for AC servo drives and includes actual examples of their application to explain the latest technology and product trends. In addition to providing idea hints to customers, I hope that the feature will raise your interest in Yaskawa products and technologies.

Motion Control Market Trends and Yaskawa Initiatives

The motion control market continues to be affected by the waves of advances and slowdowns in the global economy, but it is expected to show sustained recovery. In terms of the scale of the markets, there continues to be a shift towards China and the emerging nations in Asia and elsewhere. However, in the aspect of technology, new trends such as the representative Industrie 4.0 are becoming significant.

Yaskawa has responded promptly to these market trends and continued to offer state-of-the-art motion control products. Recent examples of this are the initiatives for new model development and an expansion of functions for the Σ-7 series AC servo drives and MP3000 series machine controllers. Other examples include the initiatives for the strengthening of motion networks and the introduction of cloud services.

This article gives an overview of the recent market trends and Yaskawa initiatives as a general introduction to this servo drive feature.


Σ-7 family

Hollow Servomotor SGM7T


SGM7T model

In the previous Σ-III and Σ-V series AC servomotors, Yaskawa has offered hollow servomotors specifically for customized use as a response to the requirements for motors that contained hollow shafts as a measure to realize more compact facilities. The requirements for more compact facilities are equally strong as those for faster and more accurate facilities and there are great expectations that hollow servomotors will help realize this move to more compact facilities. A hollow servomotor has now been included as a standard product in the lineup of the current Σ-7 series to ensure a precise response to these market requirements.

This article describes the background of the development of the SGM7T model hollow servomotor and the merits and specifications of this model.

LinearΣ F-Type Linear Servomotor SGLFW2


Application of short turnover

Flat type linear servomotors with a core are used to realize high precision positioning and position settling in a short period of time in applications such as the positioning on semiconductor manufacturing equipment and the feeding mechanisms on inspection equipment. However, there are currently demands for even greater maximum thrust and miniaturization on these servomotors.

To respond to these requirements, Yaskawa has added the SGLFW2 F-type linear servomotor to the product lineup. In comparison with the previous products, this linear servomotor achieves higher maximum thrust, further miniaturization, higher accuracy, energy saving and improved safety.

This article describes the background of the development of the SGLFW2 F-type linear servomotor, the initiatives in that development and the merits of the product.

Σ-7 Direct Drive Servomotors SGM7D, SGM7E, SGM7F


SGM7D model


SGM7E model


SGM7F model

Yaskawa has been supplying direct drive servomotors to the market since 2001. In order to respond to the demands in recent years for smaller sizes (flatness, small diameter), high precision and short tact times (high speed, low inertia), Yaskawa has now launched the SGM7D model, SGM7E model, and SGM7F model products as the latest the Σ-7 series products. These models all have a high resolution 24-bit reflection type encoder. The SGM7D model is a product that prioritizes high torque and high rigidity, the SGM7E model is a product that prioritizes small speed variation and smooth movement and the SGM7F model is a product that prioritizes a compact size and shorter tact time.

This article describes the merits of each model and of the high resolution 24-bit reflection type encoder.

Σ-7 Batteryless Absolute Encoder

Encoders are essential for servomotor position detection and can use either the incremental method or the absolute (absolute value) method. The absolute method is superior in its functions, but it previously required a battery for the saving of the position information (multi-rotation amount), so there was the issue that the device management was complicated. Yaskawa aimed to design a batteryless absolute method encoder as one part of the development of the Σ-7 series and realized a simplification of the wiring and a maintenance-free design.

This article describes the principles, merits, and specifications of the Σ-7 batteryless absolute encoder.


Mechanism of the Yaskawa batteryless design

Σ-7 Series Optimized-for-Application Type Servo Drivers

As the fields using motion control became more diversified in recent years, various requirements specific to individual markets became more prominent. These specific requirements included requirements for higher precision, higher speeds, and cooperative motion control, for markets such as semiconductors and electronic components. Responding to these requirements therefore became an urgent task.

To respond to this shift to more diverse and more sophisticated market requirements, Yaskawa has developed the Σ-7 series FT specification servo drivers to improve the product lineup. These products incorporate the optimal functions for the customer applications and have made it possible to offer the optimal solutions to customers in various different markets.

This article describes the outline, merits and uses of these optimized-for-application servo drivers.


Positioning of Σ-7 series FT specification products

Super Large-Capacity Servomotor


Ultra-large capacity servomotor (450 kW)

In recent years, the necessity for global environment protection and the improvement of working environments has led to an emphasis on measures such as energy-saving and improved cleanliness and the reduction of pollutants. For this reason, there have also been increasing requirements in the large-scale machinery sector for the replacement of the conventionally used hydraulic drives with motor drives. This sector includes machinery such as presses and injection molding equipment, representative examples of which are the production machinery for automobiles. The motor drives are required as a power source that is clean and can also improve performance.

In addition to developing a lineup of energy-saving and high-performance servomotors, Yaskawa has also promoted the development of super-large capacity servomotors to respond to the expansion of the market for large capacity servomotors for large-scale machinery.

This article describes the issues for ultra-large capacity servomotors and gives an overview of their development and of the products.

Super Large-Capacity Servo System

The requirements for energy-saving and improved cleanliness on large-scale machinery such as presses and injection molding equipment have led to a shift from hydraulics to motorization, particularly with a shift to the use of large capacity servomotors. The majority of this market for large capacity servomotors is for compound servo systems where multiple servo drivers are used to control a single motor. However, there were problems with the conventional systems in that it was not possible to effectively use the regenerative energy from the motor and it was not possible to use complex motion commands.

To find a solution to these problems, Yaskawa launched a compound control unit, a servo driver for compound control and a DC/DC converter. This realized a super-large capacity servo system that can achieve higher energy-saving and more complex control than was possible on the conventional systems.

This article describes the super-large capacity servo system and an overview of these products.


Complete synchronization of multiple axes

Σ-7C Two-Axis Servo Driver with Built-in Controller

In the manufacturing sector of equipment for industry, there are increasing demands for more compact machine components, reduced wiring and distributed systems, in order to improve productivity and the flexibility for line changes, to enable thorough automation and to support the production of various products in small volumes.

Yaskawa has worked to develop market-specific models of the Σ-7 series AC servo drives as products with high added value that provide fine-detailed responses to the customer requirements in the target markets. As one of these market-specific models, the Σ-7C two-axis servo driver with built-in controller is a product that simultaneously achieves both a compact equipment configuration and good expansibility.

This article describes the background of the development of the Σ-7C, the outline and merits of the product and examples of its application.


Σ-7C product concept

Σ-7F Integrated Servomotor

In order to respond to the requirements for production equipment with more compact and faster and more accurate movement, Yaskawa has developed a Σ-7 series servomotor with a built-in amplifier, the first such product in the world to contain a gallium nitride (GaN) power semiconductor. The use of a servomotor with a built-in amplifier makes it possible to replace multiple servo driver units inside the control panel with one converter, so the control panel can be made smaller and it is possible to improve the flexibility, such as for increasing the number of servo axes in the system. The amplifier part using a GaN power semiconductor not only makes miniaturization and higher efficiency possible, it also achieves energy-saving and noise reduction and can respond precisely to market requirements.

This article gives an overview of the development of the integrated servomotor and its merits and specifications.

Conventional system


Conventional system and Σ-7F

Engineering Tool SigmaWin+ Ver.7

As the move to higher performance and greater functionality on servo drives is proceeding rapidly, the engineering tools used for their setup and adjustment are becoming increasingly important. Yaskawa has developed the SigmaWin+ Ver.7 engineering tool that has been optimized for the latest Σ-7 series of AC servo drives. SigmaWin+ Ver.7 supports the various processes from the setup of a servo drive to its tuning and maintenance. It also realizes easy model expansion, globalization, system orientation and ease of design and use, features that were previously insufficient on SigmaWin+ and made it difficult to respond fully to the requirements and issues of the market.

This article describes the market requirements and issues addressed in the development of SigmaWin+ Ver.7 and the merits of the product.


SigmaWin+ Ver. 7 system configuration

Cloud Service MechatroCloud

With concepts such as the Industrie 4.0 initiative proposed in Germany, the new trend towards the IoT (Internet of Things) is accelerating in Japan and around the world. Yaskawa has been working on automation for some time and it will be important to further extend this direction to go on to make proposals of production systems that fit this new trend as a Yaskawa version of Industrie 4.0. As specific action for this, Yaskawa has developed the MechatroCloud cloud service for the motion control sector, which links to the Yaskawa Electric cloud platform, and has also developed the BTO (Build to Order) service and SigmaTouch! application for smartphones that are offered via the cloud service.

This article describes the background of the development of these products, the initiatives at Yaskawa and the merits of each service.


Services provided via MechatroCloud

Motion Control System Applications


Application of Σ-7C and Σ-7S

Yaskawa has offered a lineup of motion control products (such as the MP3000 series machine controllers and Σ-7 series AC servo drives) to respond to the sophisticated requirements from the market in the sector of general industrial machinery, including for the requirements for tact time reduction, high precision and flexible system configuration. Furthermore, Yaskawa has worked to expand and improve the Σ-7 family through the development of products such as the Σ-7C two-axis servo driver with built-in controller and the Σ-7 series FT specifications optimized for applications. These have promoted the use of the products in sectors where sophisticated control is demanded, such as PCB (Printed Circuit Board) inspection tools and automatic labeling equipment, and the products are responding to the customer requirements in these areas.

This article describes some examples of the application of motion control products.

[Product News]AC Servo Drive Σ-7mini Series



Yaskawa aimed to “make the driving part of machinery smaller, faster and more accurate” and in August 1997 launched the Σ-mini series of super-small capacity AC servo drives as a series of 25 mm × 25 mm, 10 W to 30 W products. This was followed with a more compact series of 15 mm × 15 mm, 3 W to 10 W products in December 2000 and then the launch of the Σ-V mini series in August 2011, which was the successor to the Σ-mini series. These new products have been supplied to applications such as semiconductor and electronic component manufacturing equipment, coil winding machines, textile machinery, clean robots and AGV (Automatic Guided Vehicles). In recent years, demands for further tact time improvement on equipment have led to demands for even higher outputs and higher precision.

Yaskawa has now launched the Σ-7mini series of products as the successor to the Σ-V mini series. The Σ-7mini series are new models in the Σ-7 series of high performance, high functionality AC servo drives, which has been favorably received by a great number of users. The addition of these models realizes even higher performance for super-small capacity servo drives.

[Product News]High-speed Spindle Motor with a Maximum Motor Speed of 25,000 min-1


High-speed spindle motor

There are currently demands for diversification in the processing of smartphone components in Asia. To respond to these requirements, the manufacturing method used for components is the method of cutting out the peculiar shapes from an aluminum plate. As a result of this, the component manufacturers have selected the use of compact #30 taper machining centers as the machine tool for component processing. The manufacturers acquire large numbers of these machines for the large-scale machining of aluminum components for their production. In applications such as this, it is necessary to have a spindle motor that is compact and high speed in order to improve the aluminum processing efficiency. In addition, in order to achieve even higher quality surface machining, it is required that the spindle motor has high speed, low vibration, high rotational accuracy and low heat generation.

In response to these requirements, Yaskawa has worked cooperatively with machine tool manufacturers by supplying motors and drivers and has now launched a high-speed spindle motor with a maximum motor speed of 25,000 min-1 for #30 taper machining centers.