مقدمة
ال automation production line continues to expand, and the deployment scale of industrial robots and various automation equipment is increasing year by year. As the basic support unit of the entire system, the performance of the power supply directly determines whether the equipment can operate stably. The on-site working conditions are complex and varied, with conditions such as vibration, enclosed environment, and dynamic load fluctuations. Industrial power supplies need to face a large number of challenges that ordinary power supplies would not encounter. After tracing the faults of most devices, they will eventually point to power related abnormalities, and the shortcomings in power supply design will amplify the risk of failure of the entire automation system. This article discusses the three core challenges in the field of automation equipment power supply, sorts out practical problems in engineering scenarios, and provides corresponding design ideas and selection references.
Power Architecture in Automation Equipment
The power architecture of automation equipment generally consists of front-end AC input modules, rectification units, DC bus energy storage components, and multiple isolated output branches. After the mains power is connected to the control cabinet, EMI filtering is first completed, and then converted into DC power through a rectification circuit, which is transmitted to the DC bus; The bus voltage will supply multiple loads such as servo drivers, controllers, sensors, etc. The power supply requirements for different functional units are not uniform. Servo motors require power supply branches that can instantly output high currents, while PLCs and communication modules require voltage fluctuations to be maintained within a very small range. Within the entire architecture, each load does not work independently, and the start stop and action switching of the load will interfere with each other. The sudden change in current of a single load will be conducted to other components along the busbar, which is also the underlying reason for the frequent occurrence of power supply problems in automation equipment.
Challenge 1: Managing High Peak Currents During Motion
Why industrial robots require high peak currents：
When the robot joints perform acceleration, steering, and grasping actions, the servo motor needs to instantly output a huge torque, and the generation of torque depends on the supply of high peak current in a short period of time. Robots do not maintain a constant load continuously, and their actions vary intermittently. When in static standby mode, the current consumption is very low. During startup and commutation, the current will surge to several times the rated current in a short period of time. The greater the mechanical inertia, the faster the action switching, and the higher the required peak current; The power supply must be able to quickly respond to this instantaneous current demand, otherwise the motor action will experience lag and the positioning accuracy will also decrease.
Impact on power supplies and DC bus stability：
High peak current will cause a voltage drop on the impedance of the bus line, directly lowering the DC bus voltage. When the voltage drop reaches the threshold, the controller and sensor will trigger undervoltage protection, and the equipment will shut down directly; Severe fluctuations in current can also cause bus voltage oscillations, which can couple into communication lines and interfere with data transmission. If the output response speed of the power supply itself is insufficient to keep up with the sudden change in current, the fluctuation of bus voltage will continue to amplify, and even cause overvoltage damage to the device.
Common issues：
Many project design stages only select power sources based on the average current of the equipment, ignoring the peak current demand at the moment of action, resulting in insufficient reserved rated power capacity. The capacity configuration of the busbar capacitor is too small to buffer instantaneous high currents; The cable selection is too thin and the line resistance is too high, further amplifying the voltage drop problem. Some systems may also experience brake energy backflow into the bus, causing the bus voltage to rise and triggering overvoltage alarms.
Engineering solutions：
When selecting a power supply, in addition to the average operating current, the focus should be on calculating the peak current and duration within the action cycle, and reserving sufficient power margin. Add busbar energy storage capacitors to absorb and release instantaneous fluctuating currents, and suppress voltage transients; Select low impedance bus cables to shorten the length of power circuit wiring. Add a brake release circuit to dissipate excess electrical energy when the motor decelerates and recharges energy, preventing the bus voltage from continuously increasing; At the software level, the motor acceleration is limited to reduce the peak current surge of a single action.
Challenge 2: Noise and EMI in Closed Control Cabinets
Sources of EMI in automation systems：
Inside the control cabinet, servo drives and switch power supplies are the main sources of electromagnetic noise, and high-frequency switching of components can generate high-frequency voltage and current noise. Noise will spread outward through two ways: one is through power line conduction, which propagates along the power line to other components inside the cabinet; The second is spatial radiation, which propagates in the form of electromagnetic waves within the interior space of the cabinet. Parallel wiring of motor power cables and signal cables can also couple additional interference signals. The control cabinet space is narrow, and various circuits are densely arranged, making noise more easily spread.
Impact on PLCs, sensors, and communication buses：
PLC、 Position sensors and industrial bus communication modules mostly handle weak voltage signals and have weak anti-interference capabilities. EMI noise superimposed on the signal line can cause signal acquisition distortion and sensor feedback position data errors; Data packet loss and garbled characters occur on the communication bus, and instruction transmission between devices is interrupted. When there is severe interference, the PLC may trigger incorrectly, causing unexpected actions of the robot and posing a safety hazard to production.
Shielding, grounding, and filtering techniques：
Replace the signal cable with a cable with a metal shielding layer, which is grounded at a single point to reduce interference caused by loop current. Separate the wiring of power cables and signal cables, reserve sufficient spacing, and avoid parallel long-distance wiring. Install an EMI filter at the power input end to suppress conducted noise from entering the system; The metal shell of the cabinet is reliably grounded, providing a discharge channel for radiated noise. Unified planning of grounding network, distinguishing between power ground and signal ground, setting up different grounding points separately, and finally connecting them to the ground at a single point to avoid introducing new interference due to ground potential difference.
Compliance standards：
The electromagnetic compatibility of industrial equipment needs to meet the corresponding national standards and industrial EMC specifications. Before the product is launched on site, it is necessary to complete tests related to conducted emission, radiated emission, and immunity. The test covers various interference scenarios such as electrostatic discharge, electric fast pulse group, surge, etc., to ensure that the equipment can work stably in industrial electromagnetic environment. Equipment that does not meet the standards is prone to intermittent faults in complex working conditions on site.
Challenge 3: Thermal Management in Sealed Enclosures
Heat sources in power electronics and drives：
Switching power supply power transistor, servo driver IGBT, and bus capacitor are the main heating devices. There are losses in the process of converting electrical energy, and most of the lost energy is converted into heat. The higher the load on the device, the greater the heating power. When power devices work in high-temperature environments for a long time, the aging rate of internal materials will significantly accelerate, the electrolyte of capacitors will evaporate, and the parameters of semiconductor devices will drift, directly shortening the service life of the devices.
Why sealed cabinets worsen thermal stress：
Sealed chassis are often used in industrial sites with high levels of dust and water vapor. The chassis shell is completely enclosed and cannot directly exchange heat with the outside air through convection. The heat generated by the components can only be dissipated by the chassis shell, and the heat inside the chassis continues to accumulate, causing the ambient temperature inside the chassis to continue to rise. The temperature distribution inside the confined space is uneven, and local hotspots will form near the power device area. The temperature stress borne by the device at the hotspot location is much higher than the average temperature of the box.
Cooling strategies：
Priority should be given to using high thermal conductivity shell power supplies, relying on shell conduction for heat dissipation, and adding heat dissipation fins on the outer wall of the chassis to expand the external heat dissipation area. Reasonably arrange the position of components, disperse high-power components with high heat generation, and avoid concentrated accumulation of heat sources; Control the power density inside the chassis and avoid stacking too many heating modules in narrow spaces. Some scenarios can use heat pipes to assist in heat conduction, transferring internal heat to the outer surface of the chassis; In terms of device selection, priority should be given to using components with a wide temperature working range to enhance high temperature tolerance.
Reliability risks：
Long term high-temperature work will accelerate the aging of capacitors and semiconductor devices, significantly reducing the time for equipment to operate without faults. Temperature cycling can cause repeated thermal expansion and contraction of device solder joints and PCB circuits, leading to hidden faults such as virtual soldering and circuit cracking. Most of these types of faults do not occur continuously, but rather intermittently, making troubleshooting difficult; Under extreme high temperature conditions, power devices will trigger overheating protection, causing equipment shutdown.
System-Level Design Checklist for Power Stability
During the system design phase, it is necessary to verify the key design points related to the power supply item by item. Calculate the peak current of the load, confirm the dynamic response capability of the power supply, and evaluate the fluctuation range of the bus voltage; Check if the bus capacitor and brake circuit configuration match the load conditions. Plan the wiring scheme inside the cabinet, distinguish between power lines and signal lines, and implement shielding and grounding design; Evaluate the cooling conditions of the chassis, calculate the temperature rise of the components, and verify the temperature margin of the components. Complete EMC related simulation and testing to confirm that the noise level meets the specification requirements; Simultaneously reserve power protection functions, including overvoltage, undervoltage, overcurrent, and overheating protection, and finally conduct long-term aging tests during the prototype stage to verify the stability of the entire system power supply.
الأسئلة الشائعة
Q1:Why WEHO Stands Out
A1:WEHO has been deeply involved in the field of industrial power supply for many years, and its product design is aimed at the harsh working conditions of automation equipment, with a focus on optimizing the three major pain points of peak current impact, EMI noise, and heat dissipation of enclosed chassis. The power devices and capacitors of the product are made of industrial grade materials with strong temperature tolerance over a wide range of temperatures; The power supply has excellent dynamic response performance and can withstand frequent instantaneous high current surges. It is equipped with a complete protection circuit and can maintain stable output even in industrial environments with vibration and dust. Supporting technical support can also be provided to assist the manufacturer in completing system level power debugging, adapting to the customized needs of robots and automated production lines.
Q2:What’s the difference between industrial and commercial power supplies?
A2:Commercial power supply is designed for stable indoor environments, with minimal load fluctuations and low levels of environmental temperature and electromagnetic interference; Industrial power supplies need to withstand severe load fluctuations, high and low temperatures, vibrations, dust, strong electromagnetic interference, and other harsh on-site conditions. The device level of industrial power supply is higher, the protection function is more complete, and the output stability is stronger; Commercial power sources have lower costs, but their dynamic performance and environmental tolerance are insufficient. When used directly in automation equipment, they are prone to early failure.
Q3:How to choose a power supply for industrial robots?
A3:The first step in selection is to calculate the average working current of the robot, while capturing the peak current magnitude and duration during the action cycle, and reserving sufficient power margin. Evaluate the working environment of the equipment, confirm whether the chassis is sealed, the ambient temperature range, and match the power cooling scheme. Verify the EMC performance indicators of the power supply and confirm that it can meet the on-site electromagnetic environment requirements; Verify various protection mechanisms of the power supply and confirm that it has protection functions such as undervoltage, overcurrent, and overheating. Priority should be given to brands with industrial scenario implementation cases, and joint debugging should be carried out in conjunction with the entire system, rather than relying solely on rated power parameters to complete the selection.
خاتمة
The power design of industrial robots and automation equipment cannot be solely based on the power module itself. It needs to be comprehensively considered from the system level, including instantaneous high peak current, electromagnetic interference from control cabinets, and heat dissipation from sealed chassis, which are the three core difficulties that affect each other. The current surge caused by load action will disturb the bus voltage; The dense circuits inside the cabinet generate electromagnetic noise, which interferes with signal acquisition and communication; The accumulation of heat in a sealed environment continues to consume the lifespan of the device, and any design flaw in the loop can lead to overall machine failure. The power scheme design needs to complete the load condition calculation in advance, do a good job in EMI suppression and thermal design, and verify each item according to the system list to reduce the probability of on-site failures in the later stage. ويهو industrial power products are designed specifically for these three core challenges in the automation field. In high demand equipment such as industrial robots, they can provide stable and reliable power supply solutions, reducing production line downtime losses caused by power related failures.
