To innovate and stand out from the competition in power supply networks
The mobile robot industry is rapidly growing. By 2023 [World Robotics 2020], the market value is projected to approach $30 billion. In the near future, robots will be manufactured to solve a variety of market problems, both well-known and yet-to-be-discovered. Their tasks will no longer be limited to moving from point A to point B: they can make real-time decisions based on environmental input data and their own task parameters .
The power supply network has high power density and scalability.
Figure 1: The DC- M converter series offers operating input voltages ranging from 43 to 154V to meet these requirements. The DCM3623 can provide regulated 24 or 48V power to servo drives , other payloads, and downstream converters via battery. The DCM3623, packaged in a 36 x 23 x 7.3 mm package, delivers 240W of power with 90% efficiency. ZVS buck regulators or buck-boost regulators construct 24 to 48V lines and are typically used to power lower voltage lines.
Providing these functionalities requires motors , sensors , and processing subsystems, but to remain competitive, a robot platform must be able to quickly upgrade these components when better options become available. Achieving this quickly while maintaining size, weight, and cost targets requires a scalable, optimized Power Distribution Network (PDN) to meet evolving needs. Considering the following questions will help you find the best answers for your platform. This will allow you to design a better PDN for your mobile robots , one that your company can withstand any changes caused by variations in task parameters .
01
Is your battery designed for lightweight applications?
Has the low-loss power distribution been optimized?
You might worry about the battery's economics (cost, power supply, and lifespan) and lifespan (charge count, aging), but have you considered whether the voltage you're using will affect the overall weight of your design?
The thing is quite simple: according to Ohm's Law, you can reduce cable weight by distributing power at high voltage and low current , which requires thinner (lighter!) cables. Thinner, lighter cables also have lower resistance compared to larger cables, reducing waste heat in the system. For these reasons, there are many battery power architectures based on 48V (or even higher!) compared to low-voltage 12V solutions, and there are also highly efficient, lightweight converters available: including fixed-ratio BCMs and regulated DCM converters.
02
Does PDN address the charging interval time ?
Optimize to support current and future payloads?
Your platform will continue to evolve: faster processors , more motors/actuators, and sensor arrays requiring more power to provide more functionality. With each subsystem replacement, would you want to redesign your PDN?
Without redesigning your PDN, you can increase overall battery capacity by using additional parallel batteries at the same PDN supply voltage to store more energy. Now, you don't need to redesign for different voltages or deal with the ripple effects of related changes across the entire platform. To optimize your future PDN, choose a high battery distribution voltage of at least 48V, and the provided discharge characteristics allow for the use of fixed-ratio converters when powering subsystems is required. Fixed-ratio converters are more efficient, smaller, and lighter converters used for buck conversion. For example, your PDN can place these small, modular converters wherever you need to convert 48V to 12V or 800V to SELV voltage.
03
Does dynamic load apply to the system?
Unnecessary weight added?
One brute-force approach to powering dynamic loads is to adjust the size of the PDN distribution to achieve greater power, but if the load has a low duty cycle, a large cable is needed, significantly increasing weight to meet the demand. Another alternative to large cables is to add local energy storage near the load point, placing a capacitor nearby to provide power when needed . However, there may be a better option for optimizing the PDN: fixed-ratio converters. These converters not only function like an ideal transformer but also have the advantage of reflected capacitance from input to output (and also from output to input) . This means that the capacitor at the input looks like the capacitor at the output, with its scaling ratio being the same as the converter's conversion K-factor. A lighter solution would use a very small capacitance value at the input of the fixed-ratio converter instead of deploying a larger capacitor after the converter.
04
Should you develop a self-control plan?
Automation is crucial for improving efficiency, so even if your robot is currently manually controlled, some of these human-controlled tasks are likely to be automated in the future. Looking at current machine learning / AI hardware , you'll see that power requirements can be daunting, but Vicor solutions already meet those needs. Planning some additional power capabilities now (remember question 2!) will help you easily scale when you're ready to incorporate AI into your enhancements.
05
Should we use batteries or cables?
Don't underestimate the advantages of tethered design, especially in situations with limited workspaces, such as factories, warehouses, or arenas. In fact, robots (including unmanned and autonomous robots) have already begun using tethered power systems, which can transmit kilowatt-level power through a very small diameter cable. As shown in the diagram, with the same cable size (and weight), higher voltage results in greater power.
Figure 4: The cable allows for unpredictable operating times, so you can increase the voltage (to 400V, 800V, or higher) to provide more power as needed, supporting a wider range of functions on the platform (sensors and data collection, etc.). While this keeps the cable lightweight, don't forget that a lightweight converter still offers many advantages (remember questions 1 and 3?).
Some mobile robots require tethered cables to connect to base stations. In applications such as underwater inspection, tethering helps extend the working range and allows for high-bandwidth data transmission from cameras in noisy and harsh environments. The thinner and lighter the cables, the deeper and farther these robots can operate, but thinner cables limit the power delivery of traditional PDNs. Vicor's modular approach enables higher voltage transmission over cables while reducing cable size and weight without compromising power. Furthermore, the small size and lightweight nature of Vicor modules reduce robot weight and increase payload.
06
Has your modular approach added value?
Universal interfaces enable modularity by standardizing mechanisms, data interfaces, and power supplies. Modularity at the FRU level of a system improves field maintainability. However, at some point, your interfaces may become outdated for your system's operational needs. For example, 12V has been the standard distribution voltage for computer and automotive PDNs for decades, but now 48V is becoming more prevalent as power levels increase. To extend the value of modularity, you can use converters that enable efficient conversion within the PDN while maintaining the interface. Returning to the 48V to 12V example, the NBM2317 is a good product example, bridging 12V and 48V power supplies with efficient bidirectional conversion.
Figure 6: The first power supply chain architecture highlights the high-performance buck-boost regulator PRM power module . The PRM can create a 24V to 48V intermediate bus with 96% to 98% efficiency, powering the servo system and other downstream power modules, including fixed-ratio NBMs, ZVS buck regulators, and ZVS buck-boost regulators. Furthermore, all modules can be connected in parallel to achieve higher power conversion.
Better power supply
These 6 questions will guide you on the path to designing a PDN.
◆ Implement power distribution with less heat and mass impact
◆ Disperses heat and promotes heat dissipation
◆ Allows for increased battery capacity and eliminates PDN's dependence on battery voltage.
◆ Provides PDN scalability (power, capacity, and autonomous control)
◆ Modular design is achieved using a universal interface to allow for future capacity expansion.
