Power peak reduction and control of automatic sliding doors

Sammanfattning: When a sliding door is opened there is a sudden current peak that the electric network is subjected to. As a result of this it is difficult to design a power supply that operates the door with adequate performance while still maintaining a low power rating. In the current solution the power rating is designed for the sudden peaks and as there is no buffer of energy everything has to be taken directly from the power grid at the instance of a door opening. This thesis aims to use an energy buffer to store energy between openings and then utilize this when it needs to open. As a result of this the power grid will suffer from less sudden peaks. The power supply will also be allowed to be rated for the continuous power rather than the peaks. Throughout different solutions to solve the energy buffer have been discussed, investigated and tested. The most prevalent and thoroughly tested was supercapacitors, which are an evolution of regular capacitors and nickel metal hydride batteries. Supercapacitors have the possibility of delivering a large current and being charged with equally large current allowing for fast charge as well as discharge. However, they do have a low voltage rating, which results in a small capacity of maintaining charge. Batteries on the other hand have a large voltage while having a lower current capacity. The differences of these have been discussed at large in the report. The work shows that both batteries and supercapacitors are able to power the door. They are both able to offer a smoother power consumption and a lower power rating of the power supply. However, they have different capacities with regards to the door that they can power. Batteries are limited by the speed, weight and run style of the door. This limit is set by the charging current that the batteries can handle. Supercapacitors on the other hand are able to handle every scenario tested due to the large current capacity.