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In this paper a method to consider saturation behavior of induction machines during the finite element (FE) analysis of high frequency excitations is developed. This saturation behavior manifests itself in an additional saturation and intermodulation harmonic, when evaluating the current response related to a high frequency voltage excitation. In order to correctly reproduce these harmonics within...
The paper investigates the influence of pole-pair number on the mixed eccentricity related fault indicators extracted by means of high-frequency or transient signal injection. The method exploits the transient current response to track eccentricity- and slotting-related machine saliencies. By using the fault indicator's locus, a separation of mixed eccentricity components is performed, without comparison...
In modern electric traction drives, on-line monitoring offers the advantage to decrease maintenance cost and increase the reliability. Especially, the electrical insulation is one of the most vulnerable components of an ac machine. Fast switching of the inverter results in high output voltage slew rates increasing the stress on the insulation as well as the rate of deterioration. The described stator...
Reflected wave transient phenomena in voltages and currents of inverter-fed drives caused by voltage source inverters (VSI) operating with pulse width modulation (PWM) with high dv/dt rates are well known and analyzed in many studies. The reflection phenomena occurring at the machine terminals, resulting in high overvoltages are one reason for the stress and aging mechanism of AC machines insulation...
This paper investigates the feasibility of sensorless position estimation from PWM-induced transient excitation sequences, present during inverter-driven operation of induction machines (IM) with standard space vector PWM (SVPWM). The applied method exploits existing machine saliencies and their correlation to the current slopes measured in response to a voltage pulse at the machine terminals. Determination...
Stator insulation defects in the machine winding of traction drives can be analyzed by evaluating the current response resulting to inverter induced voltage injection. Due to effects occurring during the aging of the insulation, e.g. change of parasitic electrical components, deviations of the high frequency components of the current response can be monitored. The insulation degradation of a stator...
The paper analyses the influence of induction machine (IM) design on rotor slotting harmonics used for sensorless control strategies. These harmonics have a direct impact on flux and rotor position estimation accuracy. Therefore prediction of their magnitude helps in selecting suitable machine designs with regard to stator/rotor slotting and winding configuration. The paper at hand focuses on the...
Condition monitoring is gaining more and more importance in the past few years. As inverter fed operation puts additional stress on the machine's insulation system a breakdown of a drive system associated with costly outage of industrial processes or production plants is getting more likely. To enable a monitoring of the insulation system health state before an actual short circuit and breakdown occurs...
Stator insulation defects in traction drives machine windings can be analyzed by evaluating the current response after a voltage step excitation. The status of the stator insulation material regarding aging, is observed in a longer perspective. Because of the fact that insulation degradation of a stator winding system is a long developing process, a deviation of the parasitic electrical components...
In modern drive applications fed by voltage source inverters, monitoring systems are of advantage to reduce the maintenance costs and prevent outages. The proposed insulation monitoring method detects stator insulation defects by evaluating the current's transient response after step excitation by the inverter. Due to fast switching of the voltage source inverter at high output voltage dv/dt rates,...
In this work a method to detect insulation degradation of an adjustable speed drive (ASD) based on analyses of the transient current reaction caused by inverter switching is proposed. The drive system consists of an inverter fed three phase induction machine with 1.4MW. The standard current sensors are used to analyze the transient signal ringing to extract an insulation state indicator of the winding...
Sensorless field oriented control (FOC) strategies have found their place in industry applications during the last few years. Stimulated by this development scientific research continues to improve their performance, which is directly linked to the estimation accuracy of flux and rotor position without a mechanical sensor by means of high frequency or transient excitation. The influence of induction...
The demand of monitoring systems to prevent a breakdown of electrical machines is continuously increasing. Regarding economic issues, usage of system resources and additional components to establish monitoring is restricted. With the method proposed, the evaluation of the stator insulation condition of all three phases is possible using only the two current sensors already available in modern drive...
In modern traction drives the application of monitoring systems is growing to ensure continuous operability. Because of the voltage source inverters (VSI) and the high steep voltage change (dv/dt), increased stress of the winding insulation exist. Stator insulation faults are common reasons for a machine breakdown. Insulation health state can be examined by evaluating the transient reaction to a voltage...
Application of monitoring systems is growing in modern drive applications to ensure continuous operability. Insulation health state can be examined offline by evaluating the transient reaction to a voltage step excitation. Using the inverter as a source of excitation, it is possible to perform an insulation test by evaluating the resulting transient current sensor signals available in modern drives...
In modern traction drive applications condition monitoring is getting more and more important. Insulation health state monitoring can be done by evaluating the high frequency current response to voltage step excitation by the signal analyses of the current sensors, which are also used for the control of the machine. This reduces the costs and number of necessary system components. A change in the...
A high number of breakdowns of adjustable speed drives (ASD) is caused by a fault of the machine, especially stator related insulation faults frequently occur. The evaluation of the insulation condition is possible with the current sensor signals only. The analyses of the transient part of the current response give evidence if a change in the insulation system occurred. The degradation of the insulation...
A new fault detection method for induction machines (IM) is analyzed with respect to transient magnetic material behavior by means of finite element (FE) modeling. The detection method uses the machines inverter to excite the IM with transient voltage pulses and measures the corresponding phase current responses. To account for the material behavior transient BH curves are identified from measurements...
Detection of rotor bar asymmetries in induction machines operated by an inverter can be difficult due to disturbances introduced by the fast switching power devices. Furthermore interference of the fault indicator with control dynamics of the load level lower the accuracy of most detection methods proposed. These disturbances can be avoided if the detection can be realized at standstill of the drive...
Controlling an ac machine without speed or position sensor at zero frequency requires the extraction of its inherent or engineered saliencies. This extraction is currently linked to injected high frequency or transient test signals that are superposed to the fundamental wave. These test signals also affect noise emission, maximum inverter output voltage, and switching frequency. Different methods...
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