Tuesday, May 21, 2013

Next Generation Motor Drives

Over the last decade, the semiconductor industry has made great advancements at the component level, especially in power handling capacity, speed and compact size. Due to availability of right power electronics and logic controllers, motor controllers have significantly progressed achieving tighter motion control and increased reliability to different motor types. However Brush-less DC Motors (BLDC) are becoming the preferred choice for low to medium power needs due to its mechanical reliability.

There are many popular electronic products out there using BLDC drives that are not updated to the latest innovations in microprocessor, power electronics and motor control loop algorithms. The reason behind this may be that these products are popular and generating revenue. Unfortunately, these products will not compete with similar newer designs having the latest BLDC drive controller, for many reasons such as: reliability, performance, efficiency, size, weight and cost. Often enough, established OEMs disappear from the market in a blink of eye, due to obsolete products. Over the years we have seen several examples of famous manufacturers in the mobile phone industry parish. BLDC technology is no different, it’s never too late, to upgrade your existing products to ensure your end user trouble free use.

The old methods are based only on speed control loops within the hardware, and specifically dedicated to the motor control chip. Today’s current BLDC motor speed controls play an important role in modern day motor electronics. The control methods are usually divided into two main types, open loop and closed loop. Dual closed-loop speed control is a common control system, with an inner loop for current or torque, while the outer loop is for speed. Dual closed-loop systems provide greater flexibility over Single closed loop systems in various ways, including non-linear control, peak current & bus voltage, deep predictions during acceleration, smart regenerative braking, etc.

Compared with the dedicated motor control chip (analog), the digital control system has the following advantages:
  1. The digital devices have higher reliability, flexibility and stability compared with analog devices.
  2. A digital control system has a higher anti-disturbance ability.
  3. A digital control system could implement more complex control algorithms.
  4. A digital system is more suitable to communicate with top-level system or remote control unit so as to construct a distributed control network.

Digital control systems with dual closed-loop control algorithms can be made independent of motor parameters without changing software or hardware.  This allows any OEM the flexibility to switch motor manufacturers, giving them the ultimate freedom of choice. New algorithms can be upgraded within the software controlling the motors at any point in the field with no down-time.  If wireless technology is utilized, upgrades or new versions can be downloaded seamlessly as well.

It’s never too late to better your Product to be more reliable or efficient. Do it wisely today, as your Company will benefit from your Customers appreciation of innovative thinking.

This article was written by Sam Sangani Jr., PNC Inc.’s Fellow Design Engineer. you can reach Sam via e-mail at sam@pnconline.com.