The demand for more reliable and efficient electric machines and drives is constantly growing in the renewable energy and transport electrification sectors. Such drive systems are usually fed by semicond.
Why do inverters have a common-mode voltage?
When there are common-mode impedance paths in an inverter system, the common-mode voltage allows common-mode current flow at every voltage variation. By producing large common-mode current, common-mode voltages in the inverter worsen electromagnetic interference (EMI).
PWM-controlled inverters produce substantial common-mode voltage (CMV). CMV causes motor/drive malfunctions and, eventually, system breakdowns. CMV can greatly be reduced by using advanced inverter topologies and modulation techniques. This paper provides a comprehensive review of the many works published on this topic.
Does a two-level inverter convert DC to AC?
While a two-level inverter converts DC to AC, it generates total harmonic distortion (THD) and common-mode voltage. The common-mode voltage in inverters is harmful to the motor, especially the bearings. Industries relying on large motors employ common-mode voltage reduction methods to prevent their machines from malfunctioning.
How do inverters convert DC to AC?
When inverters convert DC to AC power, there is a voltage difference between the power source and the neutral point of the load. This voltage difference in inverters is referred to as common-mode voltage. Consider a three-phase inverter supplied from a single DC source and connected to a three-phase load.
Multilevel inverters generate lower common-mode voltage compared to two-level or three-level inverters. Therefore, increasing the output voltage levels by using multilevel inverters is one technique that can be employed for reducing the common-mode voltage in an electrical system with inverters.
In three-phase inverters, modifying the topology by adding a fourth leg is suitable for reducing the common-mode voltage. Utilizing dual bridge inverters is also a reduction method used for common-mode voltage in conventional inverters. These reduction techniques are based on hardware circuitry.