Power Converters

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Variable sinusoidal power source

European harmonised standards in the form of EN 60335-1 require product testing at rated, minimum, and maximum voltages and frequencies which require a special sinusoidal power supply.

In 2015 we were commissioned by a client to design and build a galvanically-isolated 6kW power supply with an easily adjustable output voltage and frequency. This was used for type testing of the company’s products at various sinusoidal voltages at 50-60Hz. The power supply was later modified for higher power ratings.

The special power supply also turned out to be useful for other clients. Also added were precise output power measurement, voltage stabilisation, and smart HMI panel with remote control and supervision over Ethernet and a smart phone app. Due to excellent output stability the same converter can be used as a voltage stabiliser with flexible signalisation programming options.

The AC sources are based on industrial low voltage components and are available up to the MW power range.

Sinusoidal voltage source with adjustable frequency.

Ultra-capacitor energy storage testing unit

It was necessary to test ultra-capacitor energy storage to ensure an uninterrupted supply of induction motors.

The design for an ultra-capacitor UPS was foreseen so that it could supply an induction motor of up to 7.5kW, which had to ride through power supply interruptions with a duration of up to ten seconds. The UPS had a nice human/machine interface with Ethernet connection and smart phone app.

The main advantage when compared to UPS with an electrochemical battery is the almost maintenance-free operation and no emissions of gases. When compared to a flywheel, the ultracapacitor UPS has no mechanically moving parts. Therefore it is safer, lighter, quieter, and does not need balancing or any replacement of bearings.

The lifetime of the ultra capacitor modules covers at least twenty years of continuous operation (about one million full charge-discharge cycles).

The ultra-capacitor UPS is environment friendly. Its use results in no lead or acid waste.

Ultra-capacitor UPS.

High voltage pulsed power source

The special IGBT modulator was needed to produce primary voltage pulses at 1kV, 500A, at 15kHz for a novel dry-type transformer and rectifier, which had to emit 10kV pulses with a total power of up to 0.5MW.

The European Spallation Source or ESS (spallation being a process in which fragments of material are ejected from the body due to impact or stress) is a Sweden-based proton accelerator. It is set to start operating in 2019. Due to the large-scale and advanced technical design of the accelerator project there are many partners around the world who are helping with the development process. One of those partners is Tallinn University of Technology. ET-EX Machina won the national procurement contest to develop and build a high voltage power source for the pulse transformer being used in the ESS. The test transformer emits 10kV impulses with a power output of up to 0.5MW at 40kV potential.


Assembly of the high voltage rectifier module.

The IGBT modulator; 1kV, 500A, 15kHz.