Design of a High Power Universal Electronic Load

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Supervisor:
Kovács Viktor
Department of Automation and Applied Informatics

Energom Electronic Ltd. sells a wide range of voltage sources and voltage converters, such as batteries, inverters, power supplies, from 1W PCB modules to multi-kW industrial devices – our customers range from personal users to bank sector. An important part of my work there is testing these products.

On the one hand, before launching a new product, a deep testing is carried out in co-operation with the manufacturer, we check product parameters, their changes under different conditions, the manufacturing tolerance, comply with relevant standards, detect possible design errors and in some cases request modifications from the manufacturer. Especially in case of cheaper products, it is common for the manufacturer to neglect the documentation of the product, hence the parameters described there are not always true, which may endanger the company's reputation. In the lower segment, the manufactured products are tested in a sample manner, but for the higher-end products, each sold device is measured, with the aim of detecting manufacturing errors.

On the other hand, in case of a user complaint a thorough investigation is required to determine the fault, and after a possible repair, check for reliable operation. It is especially common in case of batteries that, due to improper handling and storage, the product is returned with a greatly reduced capacity prior to the end of the warranty period, just as the failure of the power supplies due to incorrect wiring is not uncommon either.

In such a workplace, several devices of varying power and voltage have to be tested each day, so it is not a simple task to load them. The use of high power potentiometers is not practical, because a large number of test devices with different resistances are required to test voltage sources with different parameters. In addition to that, a frequent change in the lab environment is also required, which is an uncomfortable task with overheated loads, and we can make static tests only.

Electronic workloads are the solution to this problem. Low-power loads are already available for $100, but the price of a several kilowatts one that we need is horrible, so we decided to develop our own device – first for ourselves, and then, in case the project was successful, we would look into market entry options. Our highest power outdoor test required a load of 12kW and I did not find that much power capable portable electronic load at all on the market.

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