Finally, by increasing the internal operating frequency for these switching supplies, designers have been able to decrease overall size or, alternatively, pack a higher power rating into the same size unit. For example, a 125W supply from N2Power has a power factor correction (PFC) circuit operating at 87kHz and a half-bridge output at 43kHz. By moving both to 125kHz in the 160W design, the volume of the associated magnetics was reduced by one third, thus allowing the 160W unit to fit into the same 3-inch by 5-inch 1U footprint as the 125W supply.
Active components also are playing a major role in the shrinking of supplies in several ways. IC vendors are developing better analog components for power management, especially helpful for complex functions such as PFC. The result is better accuracy and performance at both high and low line voltages. Early generation PFC circuits could achieve power factor up to 0.99 (nearly a perfect unity value) at lower AC-line voltage of 90/110V AC, but the correction dropped to as low as 0.75 at 240V AC. Using the latest analog ICs, designs can now maintain high PFC across the full voltage range, resulting in fewer corrective components and thus smaller supply size.
The most dramatic change for supplies architecture is the inclusion of digital control circuitry in the supply’s inner workings. In recent years, processors have been used in the secondary side of the supply to monitor key points and performance, to establish some operating parameters, and to manage a communications interface port. But the primary-side control loop remained analog.
With the availability of high-performance, low-cost DSPs, digital control now extends to the primary loop, which increases the flexibility in control and operating points, including on-the-fly adaptive control and dynamic operating changes. It also affects size, by putting more of the control functions in less space, due to fewer needed ICs and passive components to implement the hardware control-loop strategy. For example, a supply using DSP control can do three-phase AC line control with about the same footprint as a single-phase unit. The DSP can also provide the required PFC with no further footprint penalty.
Don Knowles joined N2Power as the vice-president of engineering 12 years ago after more than two decades in power electronics design and manufacturing sectors, spanning industrial, ICT, and medical electronics. He holds a degree in Electronics from American River College, Sacramento, Calif.
But sarcasm and irony are so much fun :) I'm also very annoyed by products that don't work as they should and/or or difficult/impossible to repair. It makes you wonder why anyone ever bothered to make them in the first place.
Ann, sorry about that. I don't do much sarcasm, nor irony. Quite possibly I am way to serious about things.
I am quite critical of both laziness and stupidity, though. I do catch grief for that on occasions.
Really though, there are a whole lot of companies that appear to be successful that have products that are very challenging to even diagnose, let alone to service. Some of them get into the "made by monkeys" section of this fine publication, some don't.
Ann, there are a whole lot of products that are simply not worth repairing. Others aren definitely worth repairing and happen to be conveniently repairable. THAT did not just happen: designing for repairability is cloesly linked to designed for assembly. Only just a bit more effort.
But it also has an extra benefit, which is a design using components available from multiple sources. So that when I can't get parts frpom one maker, I can use parts from another maker. That is quite handy.
William, I agree. But apparently the math needed to figure that out is too complicated for some companies, or they are too short-sighted. In this case, one hardly needs 20/20 hindsight to come to your conclusion.
What I find is that to provide the quality in my product that justifies the price I need to use a power supply that is quite a bit more expensive than the cheapest one that would work. But the adequate margins abd better construction have meant that no failure have occured in ten years. That has been quite good for the products reputation. It IS INDEED cheaper to do things right the first time.
Ann, Yes that example story is one of many challenges working with an OEM who's life line was soley dependent on outsourcing to Chinese Manufacturers to save a buck.
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