Industrial robot controllers are exposed to various adverse environmental factors.
TME – Transfer Multisort Elektronik – Exceptional parameters, longevity and durability
Various challenges faced by designers and manufacturers of industrial robotics controllers are an extremely broad topic. Meanwhile, Panasonic continues its efforts to provide customers with components that meet their requirements, even the most demanding ones.
Automation is developing not only due to inevitable progress in the field of technology – it is also a result of social changes in various parts of the globe, as well as the growing world population. Industrial robots have thus become an integral part of manufacturing and distribution processes.
To minimize their failure rate, maximize productivity, and optimize efficiency (for both ecological and economic reasons), components tailored to the specific requirements of industrial applications must be used. This article presents some key challenges faced by manufacturers of electronic circuits designed for control and monitoring of automation. They are compared with the characteristics of specialized components from the Japanese brand Panasonic – which clearly illustrates the tremendous progress constantly being made in this industry.
In this article, we cover topics such as:
- Passive components in automation circuits
- Challenging environment for electronics
- Optimization of size and weight in robotics
- Characteristics of specialized Panasonic components
- Key features of capacitors for industrial applications
- Reducing the area occupied by MLCC
- Protection of capacitors in circuits exposed to vibrations
- Industrial robotics and high temperatures
- Advantages of CP-Cap, POSCAP, and OS-CON capacitors
- Construction of Metal Composite inductive elements
- Limiting the negative consequences of the skin effect
- Current measurement using low-resistance resistors
- Impact of sulfides on SMD components
- Thermal derating phenomenon of capacitors
Automation and challenges for electronics
It should be noted that the most important functions of automation/robotics are associated with its intensified exploitation. They allow for continuous (24/7) operation of plants, perform repetitive tasks, require high precision, and maximum productivity. This involves a number of technical challenges – not only in the field of mechanics but also electricity and electronics managing individual elements of installations and entire systems. The most important ones here will be: high temperature, humidity, and shocks and vibrations – each of these factors alone can lead to the degradation of components and circuits, and often such challenges occur simultaneously. Additionally, industrial robots must be compact to operate in limited space and efficiently utilize the area of machine parks.
First, it is necessary to examine the specifics of the above-mentioned conditions.
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Industrial robot controllers are exposed to various adverse environmental factors.
Harmful work environment
Panasonic components are tested for degeneration due to long-term exploitation, as well as difficult environmental conditions. The supplier’s offer also includes products designed for specific applications, e.g., capable of working in contact with harmful chemical factors or in circuits subjected to mechanical overloads. Moreover, many of them exhibit thermal stability, allowing for precise work in varied temperatures.
Weight reduction
One of the best ways to increase the overall efficiency of systems is miniaturization. Reducing weight leads to limited energy consumption, as well as reduces inertia introducing the risk of damage to PCB circuits and contributing to the wear of gears or levers. To simultaneously not worsen the electrical characteristics of controllers, it is necessary to use components that are not only compact and relatively lightweight but also high-performance. This also achieves dense space utilization.
100SXE15MX Capacitors
ETQP3M1R0KVP Inductors
ERA3ARB753V Resistors
Panasonic components for automation
Considering the described challenges and requirements, it’s time to look at the range of Panasonic components. Below, the issues are considered in relation to the three most popular types of elements: capacitors, inductors, and resistors.
Capacitors
Panasonic polymer capacitors are characterized by low ESR (equivalent series resistance) and optimal behavior at high frequencies, ensuring stable operation regardless of temperature or initial polarization (DC component, bias voltage). In many respects, they surpass electrolytic and ceramic solutions, thereby increasing the efficiency of the robotics controller.
Miniaturization
In the context of miniaturizing electronic circuits, considerations regarding the selection of capacitors often begin with MLCC elements (multilayer ceramic capacitors). Today, it is one of the most popular components, used in almost every device – of course, Panasonic also supplies such products. Unfortunately, their operating principle does not guarantee ideal results. Primarily: a characteristic feature of MLCC is a significant loss of capacitance under the influence of DC voltage and a decrease in capacitance at high and low temperatures.
If the capacitance of an MLCC capacitor drops by 80% when 15V DC is applied, and the influence of temperature (too low or high) causes an additional reduction of about 10%, in some applications, it must be assumed that the effective capacitance of the component is about 20% of its nominal value. If a designer wants to achieve 47µF using 22µF elements, they are forced to assume:
47µF = n × 22µF × 20%
After transformation, it turns out that:
n ≈ 10.7
Therefore, in the circuit, de facto, 10 capacitors must be used. Of course, an alternative would be to use components with greater capacitance, but such in MLCC technology and SMD format are rare, so basing the project on them would involve additional costs and dependence on market whims.
In such cases, Panasonic’s assortment comes to the rescue, which includes miniaturized tantalum-polymer SMD capacitors. They do not exhibit significant capacitance drops under the influence of DC voltage or temperature changes. Therefore, 10 MLCC 22 µF elements can be replaced with one polymer capacitor with a capacitance of 47µF. Moreover, the size of such a component is so compact that, in effect, the circuit will occupy less space.
Vibration resistance
Traditionally, in circuits exposed to vibrations or regular shocks, reinforcement was used with adhesives (glues) to help immobilize the element. This limits the risk of their disconnection from the circuit. In the case of Panasonic hybrid (aluminum) capacitors, additional mechanical fastening is unnecessary. They withstand accelerations up to 30G (with diameters from 6.3mm to 10mm). Moreover, these elements offer a wide selection of capacitance while handling high currents, leading to minimizing the weight of the entire system.
Stable operation in high temperatures
Industrial robots often work in very high temperatures (chemical vats, food processing, metal processing and welding, foundries etc.) – meanwhile, such thermal conditions negatively affect electronic components, especially capacitors. And also in this field, Panasonic offers optimal solutions. Three innovative families of supplier components exhibit exceptional temperature tolerance.
SP-Cap: Aluminum-polymer electrolytic capacitors
Panasonic’s aluminum-polymer electrolytic capacitor, known as SP-Cap, is designed for operation in extreme temperatures and offers an impressive lifespan of up to 5500h at 135°C. This exceptional durability will be a key asset of components in applications where they will be subjected to continuous and significant loads.
POSCAP: Polymer-tantalum capacitors
Another noteworthy proposal from Panasonic is polymer-tantalum capacitors, known as POSCAP. They provide performance in high-temperature conditions (at least 1000h at 125°C). The POSCAP series will be the best choice in applications where high capacitance is required in limited space. These products can replace MnO2 capacitors and ensure safe operation.
OS-CON: Aluminum capacitors with conductive polymer
Aluminum capacitors with polymer electrolyte are one of Panasonic’s flagship technologies, grouped in the OS-CON family. They are designed for applications requiring high stability in harsh thermal conditions. They offer durability and performance (even 20000h at 105°C). An example of the high reliability of these products can be the SVT series: it is characterized by an impressive and predicted lifespan of 12.8 years at 90°C.
It is also worth mentioning that the high conductivity of the polymer results in excellent parameters of OS-CON capacitors. They are characterized by very low ESR (especially compared to electrolytic and tantalum capacitors). Since they are available in capacitances reaching even 2.7mF, they provide the possibility of reducing the number of elements, which translates into miniaturization of entire robotic systems.
Inductors
Power inductors of the Metal Composite (MC) type use a composite core made of materials developed by Panasonic. They feature an integrated construction. The result of using such a construction is excellent parameters with small housing sizes, as well as resistance to heat and vibrations.
The graph compares the drop in inductance under the influence of temperature and DC current. Visible differences between wire inductors on a ferrite core (blue and navy lines) and Metal Composite type (green line).
Classic inductors based on ferrite cores are characterized by a sharp drop in inductance with increasing DC voltage (as well as due to rising temperature). In contrast, MC-type elements do not exhibit rapid saturation (reduction of inductance) caused by high current, while thermal conditions have minimal impact on their parameters. These will be particularly important features in the case of power inductors, where significant currents occur, and a lot of heat is generated.
Developed for automotive
MC inductors were developed with automotive applications in mind and undergo rigorous quality testing. Therefore, the manufacturer can guarantee a lifespan of at least 2,000 cycles of rapid temperature changes (from -40°C to 150°C) and the ability to work at a temperature of 150°C for 2000h.
Resistors
Resistors, probably the most frequently used electronic components, must be designed so that the risk of their failure (even multiplied by the number of elements) remains minimal. Panasonic understands this challenge perfectly – and therefore prepares many specialized resistors – adapted to specific functions, but also various work environments.
Low resistance of shunt resistors
The use of shunt resistors, or simply current detection resistors, is necessary in almost every controller or controller. For example: monitoring the current flowing to receivers allows avoiding overloads, failures, and even permanent damage to executive elements.
The lower the resistance introduced into the circuit by the resistor used for measurement, the better. Tests show that at currents of about 4A, reducing the resistance from 10mΩ to 2.5mΩ can reduce heat generation by about 33°C. Therefore, Panasonic has developed SMD resistors with very low parameters, whose use reduces the heating of circuits and improves their energy efficiency.
Optimized resistor parameters were achieved using two technologies. First, Thick Film, which – as the name suggests – involves applying thickened (and multiplied) resistive layers. To ensure the best possible effects, the contacts in these elements were placed atypically, along the long side of the housing. The second technology used by Panasonic is the use of a copper-nickel alloy (CuNi), instead of the traditional silver-palladium (AgPd) – as the former has lower resistance.
Resistance to sulfur compounds
Sulfur and its compounds are, from the point of view of electronics designers, some of the most harmful chemical compounds. Unfortunately, they often occur in places where electrotechnical devices operate: near highways, in areas with intense traffic, in industrial plants using machining oils, and even some molding resins. Sulfides are also present in certain natural environments (thermal springs, volcanic areas).
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Electronics working near intense street traffic are exposed to sulfur compounds.
ERJS and ERJU series resistors
The described durability problem is so severe that Panasonic has prepared a special series of resistors resistant to it. In their construction, silver was replaced with materials exhibiting greater resistance to sulfides. The supplier offers two types of such components: ERJS series uses gold electrodes, characterized by exceptional stability and resistance to sulfur corrosion. ERJU series contains a silver-palladium (AgPd) alloy with increased palladium content, significantly improving chemical resistance, limiting silver diffusion.
In tests conducted by Panasonic, the manufacturer’s solutions were compared with standard elements. Components were immersed in oil containing sulfur. In typical SMD resistors, the low palladium content caused failure after about 100 hours of exposure. In the case of the ERJU series, no similar damage occurred even after 3000h of immersion. It is worth noting: Panasonic designs these elements so that in conditions of intense exposure, the lifespan of resistors reaches at least 12000h. ERJS series (with gold-based electrodes) is characterized by even higher reliability: after 3000 hours of immersion, it shows no measurable changes in resistance value.
Stable operation and derating limitation
In standard SMD resistors, high ambient temperature (and self-heating resulting from the Joule effect) forces designers to use higher power resistors to avoid damage due to overheating. Typically, the maximum temperature allowed in applications is 70°C, while the full range of thermal tolerance reaches a maximum of 155°C (beyond which permanent failure is very likely). The ERJH resistor series from Panasonic is characterized by much better parameters: they are resistant to high temperatures, up to 175°C. This allows them to be used even in applications where they will constantly reach temperatures even 105°C. This way, stable operation of components in high-power circuits and very difficult conditions is enabled.
Summary
Passive components play a very important role in automation and robotics circuits – and the durability of entire systems depends on their durability. The appropriate selection of capacitors, inductors, and resistors ensures the durability of installations, even in demanding industries. Panasonic’s innovative solutions help build more durable and efficient industrial devices, thereby not only reducing the risk of failures and downtime but also increasing efficiency, and equally importantly – optimal use of space and financial resources.
