Operational deflection shapes of a PWM-fed traction motor

• Operational deflection shapes of an asynchronous traction motor for railway applications are investigated. The radiated noise from the tractionmotor on a train is, especially at low speeds, dominated by noise generated by electromagnetic forces. The tested motor is fed by a pulse-width-modulated (PWM) frequency converter for which the voltage is modulated as a series of pulses that are switched with a certain frequency. In this case, PWM force lines can be expected to influence the radiated noise. Therefore, detailed knowledge about the frequencies and deflection shapes of vibrations generated by PWM forces is of great importance for understanding and controlling the radiated noise and its spectral content. Vibration levels are measured on the stator shield and the operational deflection shapes are studied for several PWM switching frequencies and motor speeds. The deflection shapes with the largest vibration levels are determined. These are then compared to the expected excitation resulting from the pure PWM force lines. Changing the switching frequency, will shift the frequencies of the exciting forces. An appropriate selection of the PWM switching frequency is therefore important for the resulting acoustic radiation from the motor.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering (hsv//eng)

Keyword

Electromagnetic noise

Operational deflection shapes (ODS)

Pulse-width-modulation (PWM)

Traction motor

Vibrations

Acoustic noise

Acoustic noise measurement

Acoustic wave propagation

Counting circuits

Damage detection

Deflection (structures)

Gears

Machinery

Pulse width modulation

Rotating machinery

Structural dynamics

Switching frequency

Testing

Vibration measurement

Voltage control

Acoustic radiation

Electromagnetic forces

Operational deflection shapes

Pulse-width-modulated

Railway applications

Spectral content

Traction motors

Publication and Content Type

ref (subject category)

kon (subject category)