A Malfait

Audible noise and losses in variable speed induction motor drives with IGBT inverters-influence of the squirrel cage design and the switching frequency

This paper describes a large number of experiments comparing audible noise, losses and efficiency of different induction motors supplied by an IGBT inverter. The influence of the switching frequency on the motor behaviour is analysed. As a comparison the motor is also supplied directly from the mains. Furthermore two different motors are compared to study the influence of the rotor cage design on the motor behaviour. It is shown that the choice of the switching frequency has a large influence on the audible noise produced by induction motors. By taking higher switching frequencies, the time harmonics move to a nonaudible region. At some higher switching frequencies subharmonics appear, having a bad influence on the audible noise. At higher fundamental frequencies the audible noise of the fan dominates. The switching frequencies can cause pure tones that are very disturbing to the human ear. The influence of the switching frequency on the efficiency is rather small. Minimal overall losses appear around 3 and 4 kHz. The voltage-frequency ratio should be taken constant from the point of view of the efficiency.<<ETX>>

Losses, audible noise and overvoltages in induction motor drives

Experiments are performed to analyse the influence of the Volt/Hz ratio and the switching frequency on losses, both in inverter and motor, audible noise of the motor and overvoltages. The effect of the squirrel cage design is investigated. The cable between motor and inverter is varied to minimise the overvoltages.<<ETX>>

Measuring the electric and magnetic fields

The paper describes different methods that may be used to measure the electric and the magnetic field in an industrial environment as well as in domestic applications. The aim is to show how these fields can be measured, and to give some ideas of specific values

Influence of Switching Frequency and Squirrel Cage Design on Audible Noise and Losses in Variable Speed Induction Motor Drives with Transistor and IGBT Inverters

AbstractA large number of experiments are performed to analyse the influence of the inverter type and the switching frequency on the audible noise, losses and overall efficiency in induction motor drives. Temperature measurements both in stator and rotor give an indication of the required derating, if any. Results for a standard design motor, consecutively supplied by a transistor based inverter and IGBT inverter are compared with the behaviour when the machine is directly connected to the mains. To analyse the influence of the rotor design, a special rotor with no current redistribution is constructed and mountedin a rewound stator. Higher switching frequencies have a large influence on audible noiseand temperature, but the overall efficiency remains nearly constant. However the distribution of losses is influenced.