Analysis of Power Supply Scheme Based on a Typical 48V Robot Application
48V and robot
48V has become popular in many applications, in part because it is the highest safe voltage in general. Compared with equipment powered by the main power supply, this allows designers to reduce system protection and reduce the size of conductors (compared with 12V power supply products), thus reducing weight, cost and power loss. Motors directly powered by 48V are also usually smaller, which supports smaller and lighter connectors in robotic applications, thereby improving machine energy efficiency, dexterity and reliability while reducing weight and cost. This in turn opens up more potential opportunities for robotic applications to improve process automation in all industries.
48V is very popular in many applications today, including cars. In many on-board devices, the popularity of 48V rapidly exceeds 12V. In cloud computing, 48V power distribution is used for server backplane, cooling fan and other telecom related applications. This universality means that the equipment and subsystems of 48V power supply are generally available, which increases the selection range for designers and reduces costs with economies of scale.
Figure 1: high level block diagram of a typical robot (including power system)
Robot is a very complex system. According to different applications and functions, robot will contain many functional elements, including connection, image sensing, position sensing and motor control. There are many different power subsystems, including AC-DC conversion, battery management, DC-DC conversion, polyphase converter, point of load (POL) conversion, linear regulation and motor driver. Each of these areas requires energy-efficient solutions to enable robots to work as expected by designers.
If we look at a similar functional block diagram of an automobile or cloud computing system, we will find that it has many similarities with the robot block diagram. This brings opportunities for cross power schemes from other applications to robots. For example, eFuse is widely used in cloud computing to support heat exchange and cooling devices of storage media, such as fans. However, in robot applications, the same eFuse can be used to introduce modularization, so that even in the process of operation, the robot itself can exchange functional blocks (such as tool blocks) according to the task at hand.
Provide power scheme for 48V robot application
Many modern robot applications use 48V bus to transmit power around the system. The loss is 1 / 16 of the typical 12V bus, or thinner and lighter cables are allowed. In fixed robot installation, 48V will be generated by mains power supply and will include power factor correction (PFC) front end. Mobile robots such as UAVs and nursing assistants will be equipped with on-board batteries and charged regularly from the power adapter.
Few semiconductors can work directly from 48V and usually need to be reduced to 5V sub volt level. The non isolated pol converter plays an important role in converting the higher voltage to the level required by the IC. In some cases, an intermediate bus converter (IBC) is used to create an intermediate bus voltage (usually 12V), which is loosely adjusted with the pol converter to convert 12V into IC supply voltage. Single stage conversion is becoming more and more preferred. Many pol converters can now be used to directly convert 48V power rail to IC power supply voltage.
Like all power schemes, the power architecture of robot applications needs to be efficient, reliable and provide high power density to make the robot small and smart enough to perform its functions well. The key to achieve this goal is to select appropriate semiconductors to form various power functions in the robot.
Semiconductor solution for robot power application
Ansenmey semiconductor is a company model with application expertise and investment to provide a variety of devices and power products, enabling designers to design high-performance power solutions for robot applications.
MOSFET is one of the most commonly used devices in almost all power supply schemes. The broad product range of ansenmey semiconductor includes "super junction" MOSFETs with multiple versions, which can be used in different switch types and applications. Fast devices provide high energy efficiency in hard switching topologies, while easy drive devices are suitable for both hard switching and soft switching applications, ensuring low electromagnetic interference (EMI) and reducing voltage spikes.
Matched with MOSFET products are various high-voltage gate drivers, which support microcontrollers or other logic circuits to directly control MOSFET. Depending on the circuit structure, simple non isolated drivers (such as ansenmey semiconductor's ncd570x Series) can be used, or more sophisticated isolation schemes or high side and low side drivers may be required.
Highly integrated solutions, such as intelligent power module (IPM) and automotive power module (APM), bring many benefits. Typically, they will integrate multiple MOSFETs for polyphase motor drive with the necessary drivers. These modules provide better thermal performance than discrete solutions because all devices are mounted on the same substrate. They can also handle higher current levels while improving EMI and providing smaller and lighter solutions than discrete solutions.
