Static UPS are almost perfect electric generators. They have high reliability and, by nature, ensure (within the battery operation limits) the uninterrupted power supply. Regarding electrical features, the inverter (which is part of the UPS generator) possesses characteristics superior to those of the mains, in terms of frequency and voltage stability. The only doubtful feature is its ability to provide a sinusoidal voltage regardless of the shape of the current drawn by the load. The objective of this course is to elaborate this point and to show that modern inverters are excellent generators of sinusoidal voltage even when they supply non-linear loads. This is considered as normal since UPS devices are designed and very often utilised to supply computer/ microprocessor systems which draw non-sinusoidal currents.

This course is suitable for electrical engineers with a desire to understand how inverters impact the quality of electrical energy, especially harmonics. Presented details cover inverter types, PWM, description of micro and mini non-linear loads and harmonic filtering. Upon successful completion engineers will have better understanding of inverter technology and its impact on power quality.

Learning Objectives:

• Power quality indices
• Inverter operating principle
• Inverter types
• Inverters with PWM and appropriate regulation
• Description of micro and mini-computer loads
• Filtering of harmonics