Using a new 32-bit microcontroller (MCU) family, engineers may now have a more cost-effective way of delivering precise power control to products ranging from washers and dryers to solar inverters.
Known as the RX62G group, the new MCUs combine high performance with onboard peripherals in a way that eliminates the need for designers to employ dedicated digital signal processors (DSPs) or application-specific integrated circuits in order to achieve high energy efficiency.
The 32-bit devices incorporate specialized timers, high-speed pulsewidth modulation (PWM), and customized analog-to-digital converters. Renesas Electronics introduced the new microcontroller family at DESIGN Westlast week in San Jose, Calif.
Renesas Electronics' new family of microcontrollers could simplify control of dc brushless motors in appliances. (Source: Renesas Electronics)
"This is the first time we've integrated all these features into a microcontroller," Riteshi Tyagi, senior director of microcontroller marketing at Renesas Electronics, told us. "It allows the engineer to reduce BOM (bill of material) cost, and board space, and still provide a much more cost-effective way of driving these motors."
The need for such technologies has sprung up over the last few years, largely due to a demand for greater energy efficiency in appliances and power systems. To make it happen, however, engineers need to replace induction motors in those products with brushless DC motors, which are more suited to precision motor control applications.
Yes, I too, have a washer where you have to hold down the dial before you turn it or it slips. It's not an electronic problem, but it's one of those problems that seems to minor to fix correctly. You're lucky you were able a temporary to find a fix for your problem even if it is annoying.
Electronics can be a sticking point, Rob. Like Beth, I have a washer that stops during cycling. Mine stops because of a sensor problem. By pushing down on the topload door, I can temporarily resolve the problem and make it finish its cycle. But I've been too lazy to fix it and too cheap to hire a repairman.
That's good news, Battar. Perhaps that means the control panel will become a stabilizing element in these appliances rather than the weak element that breaks down.
I have a little experience with the Maytag Neptune. It has two circuit boards, one is the main control up in the control panel area, the other is the three phase motor control mounted near the washtub. I did have a main control board fail setting me back about 200 smackers. Thought about reverse engineering the board, but many of the parts I could not identify by the number marked on the chip. Several triacs, but strangely marked, so it was cheaper to just buy the new board. In hindsight I probably could have designed a new one, but my time is worth something.
Anyway most of the other failures were all low tech. Tub bearing failure causing a seal failure (or maybe the reverse). Another 200 bucks as the bearing is cast into the plastic. The door lock mechanism is a device they call a "wax motor". The design looks 1890s vintage (not a typo, yes 18-90). A heater turns on causing the material to expand and interlock the door till the tub is stopped. At 20 bucks for the part I just removed it and bypassed the interlock telling my wife not to open it till the motor stops.
In these experiences (I think) I have learned that the real techie parts are pretty bullet proof, but the low tech is what fails. The BOM for the main board is probably is the size of the Chicago phone book, maybe 1000 parts or so.
The motor control however is an art form, as is the motor. Whoever designed this should get an award. The designer of the main board and wax motor however should be escorted behind the factory and hung without delay! Made By Monkeys is too high an award.
Micro-controllers for brushless motor control have been around for a few years now. You can get ARM (M0, M3) based controllers with motor drive peripherals for 1$-2$, so we can expect to see more brushless motors in appliances. Actually this should increase reliability because feedback is more precise and the controller can shut down or slow a motor under unusual load conditions instead of letting it shake itself to pieces.
I'm an optimist, Beth (That may be a another spelling for the word, fool). Even so, while we've seen tons of Made by Monkeys blogs about washers breaking down because of the control panel, I believe the components in the electronics portion of appliances are becoming increasingly reliable. We'll see.
I, for one, have spent time watching my front loader stop and start during cycling (don't ask) and now that you mention it, I can attest first hand to how many times during a cycle the washer drum twists, turns, stops, starts, etc., making adjustments for load size, water intake, etc. So it makes perfect sense that microcontrollers that give engineers more ways for finetuning these movements would help boost performance. But I have to agree with Rob, it's yet one more finely-tuned piece of mechanics with the potential for break down and lots of calls to the service repair person.
Nice story, Chuck. It's amazing to see these little efficiency improvements here and there. It adds up. Let's hope these increasingly complex electronics that are saving energy in appliances do not become the breakdown element in the appliances.
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