# Technical posts on magnetic noise and vibrations

Welcome to EOMYS e-NVH University ! You will find here a wide number of technical notes on magnetic noise and vibrations of electrical machines based on EOMYS Engineering consulting, testing, simulation and research experience. Interested to know more ? Check our training website for e-NVH courses.

### What is the effect of current harmonics?

Definition The theory of AC (Alternative Current) rotating machines considers sinusoidal supply currents, but in reality it is usually composed of an addition of multiple harmonics. For a given phase,

### What is the room equivalent absorption area?

Definition The room equivalent absorption area, , is used to characterize the acoustic absorption capacity of a room. The acoustic absorption of a given room is linked to its wall

### What is the effect of temperature on e-NVH?

Impact on excitations Temperature can first influence electromagnetic excitations (e.g. slotting harmonics) responsible for magnetic noise in electric machines. It is already known that cogging torque varies with temperature due

### What is the slot/pole combination of main EV/HEV e-powertrains?

Application to e-NVH The slot/pole combination and e-motor topology (induction machine Vs synchronous machine, radial Vs axial flux, internal Vs external rotor) determine the characteristic spectra of slotting magnetic forces

### What is the switching frequency of main EV/HEV e-powertrains?

Definition The switching frequency and switching strategy determine the characteristic voltage and current supply spectra of AC electrical machines. They are chosen to maximize the converter output power, minimize electric

### What is acoustic loudness?

Context There are differences between sound parameters we measure physically and the sound perception we have as humans. For instance, we are used to describe the loudness of a sound

### What is sharpness?

Definition Sound perception is a subjective phenomenon depending on both physical and cognitive factors. The aim of psychoacoustics is to better understand the human perception of sound and improve Sound

### What is tonality?

Definitions A tone is a sound composed of a single frequency component. Sounds we hear can be either pure tones (e.g. a whistle in a quiet background), or a combination