High Peak Power AC-DC Power Supply Application and Product Selection

Introduction

As economies grow and industries evolve, the prevalence of DC motors in various applications has surged. These motors are integral to a host of devices, from homely gadgets like blenders and coffee machines to more sophisticated equipment such as banknote counters and industrial robots. A key challenge in powering DC motors involves managing the substantial startup peak current, which can often be several times the motor's rated current. To address this, there are a few strategies that designers and engineers might consider:

Upscale the Power Supply: A straightforward solution is to select a power supply with a significantly higher capacity. For instance, to accommodate a 150W DC motor with a peak current that is 300% of its rated current, you might choose a 450W power supply. While this certainly solves the problem of peak current, it leads to increased costs and a bulkier design than necessary.

Parallel Power Supply Configuration: Another approach is to connect multiple power supplies in parallel, boosting the overall capacity to drive the motor. This method, however, also leads to a rise in costs and consumes additional space that could have been used for other components within the design.

System Optimization to Minimize Peak Demand: An alternative is to tweak the system itself to reduce the initial surge of current. This could involve sequencing the motor startup processes to mitigate the collective peak current draw. While this can be effective in reducing current spikes, it's not without its drawbacks, potentially affecting the motors' startup performance.

The aforementioned approaches for motor operation clearly involve trade-offs and limitations. What's truly beneficial is a power supply tailored to sustain the motor's continuous operational power, while also having the capability to momentarily deliver a high peak power. This design not only significantly reduces cost and size implications but also simplifies the installation process. Addressing this precise requirement, MEAN WELL introduces the HRP-N3 series. This new series of single-output AC-DC power supplies comes with built-in power factor correction and is capable of providing an impressive short-duration peak power of up to 350% for 5 seconds. The HRP-N3 series is available in various models, including HRP-150N3, HRP-300N3, and HRP-600N3, to accommodate a range of power needs.

As the previous year drew to a close, MEAN WELL introduced the cost-effective LRS-N2 series to its lineup. Standing out in the new LRS-100/200/350/600 N2 series is the ability to deliver a swift 200% peak power surge for up to 5 seconds, effectively easing the challenges associated with the initial high current demands of startup applications. This means that consumers can avoid investing in higher wattage power supplies and instead rely on a standard wattage model equipped with the capability to handle transient peak power loads. Such an innovation not only cuts down on acquisition costs but also aids in resolving common application issues. The series offers 12V, 24V, 36V, and 48V models, meeting the standard voltage requirements for a wide range of industrial machinery. Moreover, the LRS-N2 retains the same physical dimensions as its LRS predecessors, thus ensuring a straightforward replacement process for existing customers.

Product Selection

To use the peak power products, there are several requirements to follow:

<p>Figure 1. High Peak Power Period Diagram</p> — Figure 1. High Peak Power Period Diagram

Example for Power Selection:

A 24V DC motor for an application of banknote counter with power requirements below: peak current: 66.7A (800W), peak power duration: t < 5sec. with duty 10%.

What is a suitable power supply for this application?

1. According to its peak power requirement, there are HRP-300N3-24, HRP-600N-24 and HRP-600N3-24 that can be candidates. Let’s select HRP-300N3-24 first, which is the smallest one in power rating for matching.

2. Do a calculation by following the formula and peak output power curve (Fig. 2).

If you choose other duty, you can use the interpolation method to calculate the corresponding peak power according to the curve.

3. Conclusion:

Based on lower product cost and smaller size, it is suggested HRP-300N3-24 and adapting input range at above 200Vac. If it is required to have a full range input, HRP-600N-24 can be an alternative solution.
With the requirements of 800W peak power and t < 5sec, Period: ≧ 45sec, meaning the supply should be cooled down (or at Pnpk mode) for at least 45 sec before starting another peak power output.
Non-peak output power(Pnpk): ≦ 284.4W

<p>Figure 2. Peak output power curve for HRP-300N3</p> — Figure 2. Peak output power curve for HRP-300N3

Application Examples

Case 1: Industrial Robotic Arms

A robotic arm is a mechanical, programmable device that has similar functions to a human arm and can be used to execute a specific task. Robotic arms use motors to achieve joint movement. The HRP-N3 series can provide up to 350% peak power for 5 seconds to fulfil transient energy demands in the startup for the motors. Consumers no longer need to spend more money on power supplies with the higher rating.

Case 2: Large Printers

A large printer utilizes motors to drive the rollers. The equipment only takes a few hundred watts during the normal printing process, however, its transient power requirement reaches more than 1,000W when the rollers start working. The HRP-600N3 model can perfectly fit this application and avoid overkill design.