An unregulated power supply is preferred for servo applications because of its ability to supply bursts of current during acceleration phases, and its ability to absorb current during deceleration events.
During backdriving/deceleration events, an actuator will function as a generator and dump power into the power supply, causing an increase in bus voltage. This power needs to be safely absorbed by the power supply or else the actuator, and other components, can be damaged.
- The large smoothing capacitor of an unregulated power supply performs well at both absorbing generated power and supplying high peak power during acceleration/high force events.
- If an application requires the power supply to absorb more power than it can handle, a power shunt can be wired in parallel with the output of the DC power supply. The shunt will divert power into a low resistance, heat sunk power resistor when the bus voltage crosses a defined threshold.