Finding the sweet spot between specification and price…

Almost every financial decision we make involves a trade off between specification and price. Whether it’s looking at a new car and deciding that you will just have to go with the slightly smaller engine or a new product design that simply has to be sold at a set price to work in the market, there are compromises that have to be made everywhere.

However, compromising too much on quality for the sake of price can be a false economy. The English language is full of proverbs and ‘wisdom’ as such;

“ You buy cheap, you buy twice”

“The bitterness of poor quality remains long after the sweetness of low price is forgotten”

Even John Ruskin weighed in…

“It’s unwise to pay too much, but it’s worse to pay too little. When you pay too much, you lose a little money – that’s all. When you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do. The common law of business balance prohibits paying a little and getting a lot – it can’t be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if you do that you will have enough to pay for something better.”

In engineering terms, at least in our own work, we prefer not to think of our potential output as being cheap, but rather that compromising too much on specification in order to meet a price demand can lead to components that are simply not fit for purpose, especially in long term use. That said, there are always compromises that have to be made between designing and building a bullet proof design that would be virtually impossible to go wrong and a design that will meet the minimum requirements at a price that works for the project.

So what tools or ideas can we use to help us in finding this sweet spot.

Proper feasibility studies and initial testing go a long way

The first and most obvious point that we try to make to potential customers looking at a custom design motor controller is on the importance of proper feasibility studies and intense initial testing. Testing of this sort can really iron out exactly where the specification should be rather than where people would like it to be (this goes both ways as a criticism – the design team will nearly always want to overspecify components to ensure robustness and long life, the procurement team nearly always want to cut costs by reducing specifications).

With this type of advanced initial testing it is nearly always possible to identify exactly where the specification should be because it is tested in its real world use. A typical example of this might be a brushless DC controller that has been spec’d to run from batteries and to power a hydraulic pump. In typical use the controller would use around 10A at 24V, however this is not where the testing should be carried out. By testing this application at the extreme of it’s weight limit, at the hardest point of use (typically, though not always) startup and under the worst possible conditions (in this case when the battery is at it’s lowest useable charge where current draw will be higher) we can get the critical data that we need to understand the specification.

Once we have this we can then work out what is acceptable, what fail safes need to be included and the controller specification then nearly always writes itself.

Power is almost always the most important factor

When looking at controller specifications it is nearly always the power ratings that have the most impact on the potential specification of a unit. This is because power handling has the biggest impact on the board in terms of heat capacity, board size and also the power handling of the components. This is especially true where high current is concerned.

That said, there are a number of options to help find the best possible compromise between specification and price such as component configurations, component types, potentially splitting power sections and control sections and a range of other options. To find out more about this type of work you can browse our customisation section or talk to one of our team.

No substitute for experience, flexibility and testing

Ultimately, when it comes to finding the right balance between the two competing aims of low price and good specification, there is no substitute for experience and testing. Knowing exactly what certain components can handle, running life tests on a wide combination of different configurations and being confident in the data derived from initial testing will help to find the balance. Equally, transparency and trust in the development process are also hugely important. This goes for both discussion and pricing.

Equally, application specific testing can be hugely informative in showing exactly how different conditions and issues can have an impact on the performance of a particular driver or controller.

Conclusion: a difficult balance to strike

As you have probably seen from the discussion above, finding the right balance between these two factors can be a difficult balance to strike and one in which there is no substitute for time testing, accurate data and a detailed understanding both of what’s required in the project and of motor control electronics. The time taken to accurately test an application in order to understand the requirement in detail is hugely important in shaping the way in which the controller will be specified. Doing a poor or (more commonly) a rushed job at this point will almost always be a false economy, leading to delays, extra expense and potentially poorly performing controllers in the long run. At this point, one will simply have to stop, go back to the drawing board and do the initial work again. Equally, however, having an experienced team who understand the implications of choosing various configurations, setups and other arrangements can also be hugely important in shaping the way in which the project will develop.

As always, if you have a specific constraint or would like to discuss how we can help deliver your motor control project then please do get in touch and we’d be happy to discuss the options you have.

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