Empowering robots: Discover RECOM's DC power solutions

Almost all robots use DC drives, either brushless (BLDC) or stepper motors, to operate the wheels, actuators or gripper mechanisms, so the essential power supply unit requirements are either DC/DC converters for the mobile robots or AC/DC converters for the fixed robots.

Almost all robots use DC drives, either brushless (BLDC) or stepper motors, to operate the wheels, actuators or gripper mechanisms, so the essential power supply unit requirements are either DC/DC converters for the mobile robots or AC/DC converters for the fixed robots.

Some heavy-duty mobile robots, especially those used in applications such as warehouse transportation or off-road environments such as airports, building sites or military uses, will have two battery systems – a higher voltage traction battery and a lower voltage battery (12V or 24V) to power the on-board electronics supplied via an on-board converter.

Board-mount DC/DC converters for mobile robots need to be compact, light-weight (especially for drones) and robust. AC/DC converters for fixed robots need to have a universal input voltage, high power density and be capable of fan-less operation.

All of these variables result in a wide range of power supply requirements:

DC/DC Converters in Robotic applications

A wide input voltage range is needed to utilise as much of the stored battery energy as possible – for example, a 48V Li-Ion battery would require a DC/DC converter with a 20V – 60V nominal input voltage range, but capable of handling short 100V transients.

Many battery chemistries, especially Li-Ion, can be irreversibly damaged by deep discharge, so a DC/DC converter with built-in under voltage lock-out (UVLO) which automatically disconnects the supply if the voltage drops too low is useful.

Mobots typically have a high voltage traction motor battery capable of providing the power needed to move the robot but need a lower voltage bus (typically 5V) to power all the sensors, cameras, communication interfaces and motion detectors. For highest system fault tolerance, it is common to use multiple low power DC/DC converters to independently power each of these subsystems. Each DC/DC converter should be compact, light-weight and continuously short circuit proof, and have an enable/disable control to allow correct power up / power down sequencing.

DC Motors have a very high stall current compared to their normal operating current, but also may require high peak currents during rapid acceleration. The power supply must be able to cope with these high peak currents plus significant back-EMF voltages generated by the motors when braking, and yet safely disconnect the load during short circuit or prolonged stall conditions to stop the motor windings from overheating. For example, the RPMGS-20 is rated at 240W but can deliver 480W for a short period of time (several seconds) before the overload protection is activated.

Buck/Boost DC/DC converters (where the output voltage can be lower, higher or the same as the input voltage) can be used to stabilise the variable battery voltage to a fixed supply voltage so that the motor performance is independent of battery charge. For example, a 48V Li-Ion battery delivers 53V after full charge and 43V at almost flat. The RBBA3000 can be programmed to offer a fixed 48V output over the full battery charge range.

Cobots are designed to be used alongside humans, helping lift heavy weights or selecting and presenting small parts in complex assembly processes. Cobots use a range of technologies to allow safe sharing of the same physical space as humans, such as force sensors, camera-based virtual boundaries and AI voice-activated controls. Cobots are typically mains powered but use a distributed power architecture to power all these different sub-systems from independent single output or dual output DC/DC converters to enhance system safety and ensure fail-safe secure operation.

On-board converters are a special category of DC/DC converter because they are mobile and subject to the same harsh environmental conditions as the Mobots themselves – such as high shock and vibration, use in damp, wet or dirty environments, and needing to meet special mobile equipment safety regulations. Additionally, as they are supplied from different traction battery packs, a wide input voltage and adjustable output current limit is useful.

Some selected RECOM products suitable for robotics applications: