Have you noticed that the number of servo motion control products available on the market has been increasing in recent years? At the same time, manufacturers are launching new products at an increasingly rapid pace. Therefore, how to quickly understand these servo products and effectively select the brand series that best suits your needs has become a new challenge for equipment users and manufacturers.
In this issue, we'll first discuss how to quickly understand a servo drive product.
⚠️Before getting to the main topic, one point needs to be clarified: the focus of this article is on servo drive products in general automation equipment; while many professional servo products with strong industry application attributes in the current industrial field, such as robot joints, AGV drives, wind power pitch converters, etc., are not within the scope of this discussion.
As we all know, the function of a driver is to provide controllable electrical driving force for the movement of motors and actuators. Therefore, to understand a servo drive product, we must first look at how it is integrated into the electromechanical transmission system of the equipment. Specifically, this generally includes:
1. Start with the product's appearance to examine its hardware style and power structure, whether it is a single independent type or a modular system type.
The term "standalone type" refers to a servo product where each model's drive module integrates a complete rectifier and inverter circuit, allowing it to stand alone as a drive system. A modular system, on the other hand, means that the servo drive series contains rectifier units and inverter modules of different capacity levels, requiring combination using a common DC bus configuration to form a complete servo drive system. Some standalone products (such as SINAMICSS210, IndraDriveHCS01, and Kinetix5500) can also be combined to form modular drive systems with a common DC bus. Choosing the right servo drive system structure will largely determine the layout of its internal electrical components and the distribution of power lines.
2. From the input end, determine the type and voltage level of the power supply required for the servo drive system composed of this product.
Currently, most industrial servo drive systems use AC power as their power input, primarily in different types and levels such as single-phase 100~120VAC, single-phase 200~240VAC, three-phase 200~240VAC, and three-phase 380/400VAC. Users typically need to select the appropriate power source based on the industrial power standards of the region where the equipment is installed; otherwise, a corresponding transformer must be installed on the power supply side of the drive system.
3. Examining the power output capability of the shaft module from different perspectives:
The capacity range of the shaft-end output is generally measured in terms of power and current values, but I personally think that referring to the torque range of the matching servo motor is more intuitive.
Power output compatibility, i.e., what types of servo motors can be equipped? In addition to low, medium and high inertia permanent magnet rotary motors, does it also support various direct drive rotary motors, linear motors with or without iron cores, linear electric cylinders, etc.? Besides the servo products of the matching brand, are there also function options for adapting to third-party brand motors and actuators?
At the same time, we need to understand that servo drives are actually an electrical drive technology used to achieve precise motion control. Therefore, the control characteristics exhibited by servo drive products after being connected to the equipment system—that is, how quickly and precisely they can respond to and adjust to even the slightest load errors—are extremely important. In this regard, in addition to the hard specifications such as frequency response bandwidth and response frequency values provided by the manufacturer, the soft capabilities of the servo drive in control loop tuning are also very worthy of attention. For example: does it have self-tuning functionality? Can it achieve dynamic adaptive tuning? How many limiting filter frequencies can be set? Can the limiting frequencies be adaptively adjusted? Does it support vibration suppression? Can the number of suppression frequencies be set manually or automatically? Does it have multi-axis synchronous correction functionality?
As a motion control power component, the way servo drives are connected to the control loop of an equipment automation system also affects their performance. Therefore, it is necessary to take a look at some of the control ports on servo drives.
Operation control data port:
Servo drives can be broadly categorized into several types, including PTI pulse train input, voltage or current analog input, non-real-time industrial bus, and real-time industrial bus. Servo drives with the first three types of ports, or the EtherCAT port from a real-time industrial bus, are generally compatible with multiple control platforms and can be considered component-level products. However, servo drives using real-time industrial bus protocols other than EtherCAT mostly only support automation control systems within specific brand systems and should be considered system-level products.
Feedback port:
This mainly refers to motor feedback. It is necessary to understand the supported encoding protocols, resolutions, and wire core configurations. This is also related to the third-party motor compatibility mentioned earlier. Some drivers also have auxiliary feedback (or second feedback). In this case, in addition to the relevant parameters similar to those of motor feedback, attention should also be paid to the function of the auxiliary feedback, whether it is used as a spindle encoder, a full closed-loop feedback, or a combination of both.
I/O ports:
On the one hand, many functions of servo drives are based on the actions of external components, thus requiring corresponding control input ports, such as enable, travel limit, homing, high-speed alignment, reset, etc. On the other hand, some actions of motion control equipment are also based on the state of the servo axis (such as position), which requires the driver to be equipped with specific output ports, such as high-speed cam output, analog encoder output, analog output, etc. It is worth mentioning that with the continuous improvement of the performance of motion control buses, the number of I/O ports on new servo drives is showing a continuous decreasing trend, and their functions are gradually being transferred to the control platform of automation systems.
The preceding discussion mainly covered key product aspects related to servo drives and device functionalities. However, with the increasing number of axes in motion control systems, and considering the inherent complexity of servo technology, it's essential to consider the potential operational processes and user experience when analyzing a servo drive product. Based on personal experience, this generally includes the following aspects:
Install:
When estimating the space occupied by a servo drive in a device system, factors to consider include: power density, whether a book-style design is used, whether the heights of multiple frame dimensions are consistent, minimum installation spacing, and whether it includes dual-axis or multi-axis modules.
wiring:
Observe how the incoming ports are arranged on the front, bottom and top of this product, as this will affect the wiring layout and electromagnetic compatibility performance inside the electrical cabinet to some extent.
debug:
Check what debugging methods this product supports, for example:
Direct on-site button operation;
Wired connection, using PC-side driver debugging software;
Wired connection, using automation system software based on an integrated control platform;
Wireless communication connection, using a web browser;
Wireless communication connection, based on mobile terminal APP;
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In general, to quickly understand a servo drive product, it's necessary to analyze it from dimensions such as power structure, performance, control ports, and user experience. However, if a particular product is to be considered in a device solution, it's necessary to ask more in-depth questions based on the specific application scenario, such as:
What is the brand's reputation and the market installation volume of its past products?
In which industries and application areas is it suitable? What are its performance results?
Is there corresponding operation and control selection software?
What operational safety functions are integrated? For example: safe torque shutdown, safe stopping, safe speed monitoring, safe speed limiting...
What heat dissipation methods can be used?
Does it have regenerative braking capability?
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