Operating ACTILINK-S Integro Outside Nominal Voltage

Overview

This section explains the behavior and characteristics of ACTILINK-S Integro devices when operated outside of their 48 V nominal DC bus.

It guides the user through:

  • torque-speed performance below 48 V,

  • the voltage ripple margin above 48 V, and

  • the practical limits and precautions in each direction.

Introduction

ACTILINK-S Integro (200 W to 1000 W, models ASC1-061A through ASC1-082A) is designed and rated for a 48 V DC bus. Most datasheet performance figures - as well as validation and qualification - were established at this nominal 48 V supply voltage.

Additionally, the drive is capable of running outside of this nominal point,in both higher and lower voltages:

  • Lower voltage, down to a minimum of 24 V DC. Any voltage between 24 V and 48 V is feasible. As the most commonly used case, this note details the 24 V operating point in Operating below 48 V DC - Specifically 24 V DC.

  • Higher voltage, up to a maximum of 60 V DC. Towards the upper limit of this range (55 - 60 V), operation at high peak power may impose specific requirements on wiring and topology. See: Operating above 48 V DC.

Power Ratings across the Operating Range summarizes how peak and continuous power scale across this voltage range.

Accessories: Power Supplies and Braking Choppers describes the accessories (power supplies and braking choppers) used to establish a given bus voltage.

Power Ratings across the Operating Range

The peak and continuous power figures published in the ACTILINK-S Integro datasheet are measured at 48 V DC.

  • Above 48 V, the maximum available power might not increase. In some edge cases it might decrease because the drive may need to limit torque to keep operation stable against the higher DC-bus voltage ripple described in Operating above 48 V DC.

Operating below 48 V DC - Specifically 24 V DC

The 24 V operating point is the most commonly requested departure from nominal; specific illustrations are provided in this section.

Motor Curves

Figure 1 compares the 24 V torque-speed behavior against the 48 V datasheet reference for all five ACTILINK-S variants. Solid lines indicate the normal operating range while dashed lines mark the extended operating region at 24 V, discussed in Operating up to 4500 RPM on Lower Voltage DC Buses.

For the two 80-flange variants (ASC1-081A and ASC1-082A), the plotted 24 V continuous-torque curves are additionally constrained by the 25 A DC current limit of the power connector, since DC current at 24 V is approximately double that at 48 V for the same operating point. From the mid-speed range onward, the continuous torque of these two variants is therefore set by this current limit rather than by thermal capability.

Figure 1  -  Torque vs. speed at 48 V and 24 V DC bus voltage for all five ACTILINK-S Integro variants; line coding per legend

The extended operating region begins at ~2250 RPM at 24 V; refer to NOTE 2.

General Behavior

At 24 V, the ACTILINK-S Integro drive maintains full 48 V torque but only up to about half the rated speed. This is a rough guide: the drive's field weakening and MTPA current control strategy actively reshapes the torque speed envelope in real time; thus, the transition is more gradual and the usable range extends further than a simple voltage-halving would suggest.

Operating up to 4500 RPM on Lower Voltage DC Buses

The full rated speed of 4500 RPM remains achievable at 24 V; speed derating is not required by the drive itself. However, three effects apply in this extended operating region:

  • Torque at these high speeds is significantly lower at 24 V than at 48 V. Refer to Figure 1.

  • More heat is induced inside the motor at 24 V than at 48 V for a given operating point. As a result, continuous (rated) torque is also reduced and the motor can run comparatively hot even at low torque or no load.

  • Switching the motor off, or removing its reference value, induces a voltage on the DC bus that can approach the full 48 V rating; refer to NOTE 2.

Operating above 48 V DC

Especially in battery-based applications, the DC bus voltage may typically be continuously above 48 V DC. ACTILINK-S Integro allows for permanent DC bus voltages as high as 60 V DC.

Note that, like any motor control device, ACTILINK-S Integro's switching elements cause a voltage ripple on the DC bus. The amplitude of this ripple depends on factors such as wiring topology, installed bus capacitance, cable length, operating point, and controller configuration.

At the nominal 48 V bus voltage, ACTILINK-S Integro is very robust to such ripple, even at significant amplitude. At higher voltage, especially in the 55-60 V range, there is less margin before the ripple encroaches on the drive's protection limits. If that margin is exceeded, the drive goes into fault mode to protect itself.

If this occurs, the first thing to try is shortening the DC bus cabling, which is the most effective lever available onsite to reduce ripple amplitude. Wiring topology and installed bus capacitance are the other contributing factors and may warrant review as well.

Accessories: Power Supplies and Braking Choppers

Power supplies and braking choppers offered by Synapticon are designed for a 48 V nominal bus and can only be adjusted within narrow limits of approximately 48 V.

If an application requires a different, continuously-held bus voltage, this is typically a battery application, since a battery naturally supplies a voltage away from 48 V.

When an application requires a distinct, sustained bus voltage, it most commonly involves a battery system, given that batteries inherently deliver voltages outside of the 48 V standard.

Alternatively, a third-party power supply rated for the desired voltage can be used instead of the Synapticon unit. Make sure to select all DC bus components in line with the respective requirements, e.g., in terms of voltage, currents, reverse currents, and applicable standards.

Conclusion

ACTILINK-S Integro operates reliably across a 24 V to 60 V DC bus, allowing applications to significantly deviate from the 48 V nominal rating.

Below 48 V, torque and speed scale down together with power; the 24 V case is validated in detail in Operating below 48 V DC - Specifically 24 V DC, including the NOTE 2 precaution.

Above 48 V, the limiting factor is DC-bus voltage ripple margin rather than motor performance, and shorter cabling is the first remedy if the drive faults. Any non-48 V bus voltage that must be held continuously is best supplied by a battery or a third-party supply, since Synapticon's own accessories are specifically designed for 48 V.