Thank you for your interest in the webinar held during the Charged Virtual Conference, Measuring Torque Ripple and its Effects on Electric Power and Noise and Vibration. There were several questions asked during the course of the presentation. Our presenters, Mitch and Ed, have captured those questions and provided answers to share with you.
The inverter voltage is the energy source for the system. High frequency voltages result in high frequency current, the current becomes magnetic with frequency content, which become torque that may also have frequency content. Therefore, the voltage can have a direct influence on torque.
Control type dictates at what position and frequency energy is transferred to the rotor by the inverter. These interactions will often cause additional harmonics, which can be reflected in torque. Two common examples of controls that effect torque are six step control and PMSM field weakening.
Manufacturers are increasingly using special invertor control algorithms to improve NVH. One of the advantages of using an HBK solution, is that it allows direct measurement of the high voltage signal to the motor synchronously with the noise and vibration signals, which provides you with a powerful troubleshooting and benchmarking tool
Yes. Test stand designers should make their driveline as short and stiff as possible. This will control the amount of torsional resonance that is experienced by the system.
To eliminate electrical noise in the system HBK uses a digital frequency output from the torque sensor and reads the digital signal with high-end timer counter channels in the power analyzer.