Hans Ertl’s research while affiliated with University of Vienna and other places

... For switching transient monitoring of phase current and leakage current, it is proposed in [21], [22], [23], [24], [25], [26], and [27] that the transient characteristics of current response are used to detect insulation degradation. In [21], [22], and [23], the root mean square deviation (RMSD) of transient phase current is utilized for insulation condition monitoring of stator winding. ...

Reference:

Diversified Assessment of Ground-Wall Insulation in Inverter-Fed Motors by Using Transient Characteristics of Leakage Current

... In general, methods for employing a mode separation may be divided into four groups: 1) passive networks, which employ resistors, broadband transformers, or power combiners [11], [12], 2) active networks, like operational amplifiers [10], 3) digital or software [13], [14], 4) direct measurements with current probes [15]. In the case of additional active or passive networks, apart from the need of designing or buying a separate device, separators have limited capabilities [16]. There are several major requirements for a separating network, such as flat frequency response of a network on a frequency range of interest, the low coupling between DM and CM outputs, high (ideally infinite) DM rejection ratio (DMRR) for CM output and CM rejection ratio (CMRR) for DM output, low (ideally 0 dB) DM transmission ratio (DMTR) for DM port and CM transmission ratio (CMTR) for CM port and low introduced noise level if the active network is used. ...

Reference:

Mode Decomposition in Multichannel Time-Domain Conducted Emission Measurements

... Forming a phase-modular isolated three-phase Power Factor Correction (PFC) ac-dc converter system comprising three single-phase PFC rectifier front-ends (with individual isolated dc-dc converter stages) connected to a common star-pointN as highlighted in Fig. 1 [1]- [5] has two major advantages: First, standard single-phase PFC rectifiers [6] can be employed, which is beneficial in terms of economies of scale, design effort, and maintainability. Second, the low average dc-link voltage level of typicallyŪ dc = 400 V (compared to a standard non-modular/monolithic PFC ac-dc converter with an 800 V dc-link and 1.2 kV Silicon Carbide (SiC) semiconductors [7]- [9]) allows the usage of superior 600 V Gallium Nitride (GaN) semiconductors and thereby enables high conversion efficiencies η > 99 % even for the Table I): Each phase module comprises a totem-pole PFC rectifier front-end with an HF bridge-leg and an LF unfolder bridge-leg combined with an isolated dc-dc converter stage connected to a common dc output voltage Uout. The module starpointN is not connected to the grid starpoint N such that the CM voltage uN N does not drive any current in the grid [14]. ...

Reference:

Optimal Common-Mode Voltage Injection for Phase-Modular Three-Phase PFC Rectifiers Minimizing Energy Buffering Requirement

... The current injection device, which is utilized via bidirectional switches, is injecting a third harmonic current into the input side of the diode bridge rectifier. A more detailed description of the general third harmonic injection concept is given in [8]. ...

Reference:

Unidirectional medium voltage rectifier utilizing sinusoidal input currents

... Consequently, the hybrid rectifier meets the stringent requirements for high power quality in efficient electrolytic hydrogen production processes. Hence, the hybrid rectifier can more precisely respond to the dynamic changes in the electrical grid and the hydrogen production load, facilitating a more efficient and stable electrolytic hydrogen production process [21][22][23][24][25][26]. For instance, Bintz has designed a high-current, low-voltage hybrid rectifier topology for use in electrolytic hydrogen production. ...

Reference:

Research on Hybrid Rectifier for High Power Electrolytic Hydrogen Production Based on Modular Multilevel Converter

... We have to consider how we get from " off " to " on " , the " dynamic " area of the switching waveform (Fig. 3). The dynamic area is only a fraction of the total waveform, but it is by far the most important when it comes to parallel operation [3], [4]. The aim of this paper is researching the left diagrams (Fig. 3), turn On delays, and turn On (rise time) in parallel connection of MOSFET's in Power Inverter with mismatch threshold voltage. ...

Reference:

Impact of rise time driving signal and mismatch threshold voltage MOSFET's in parallel connection of Push-Pull Power Inverter

... Harmonics create a lot of problems [10]. Combining active and passive filter [11], switch mode regulator [12], Cúk converter in DCVM operation [9] and Cúk converter with variable switching frequency [13][14][15][16] to reduce the THD is proposed. But in every case, it is found that the value of THD is greater than 2%. ...

Reference:

Investigation of Total Harmonic Distortion of a Three-Phase Cúk Rectifier

... Considering a chronological order, the articles in the bibliographic portfolio that described online tests to assess insulation conditions, together with the principle used in the test are: [101], which assesses whether the results of the motor current signature analysis (MCSA), which identifies turns, in short, can also be used to diagnose the insulation conditions of induction motors fed by inverter and grid; [102], which has as principle the measurements of external magnetic field to detect small variations in capacitances between turns due to dielectric aging; [103], which discusses the evaluation of the transient response of the motor current in voltage pulses injected by switching the inverter; [104] and [105], in which approaches have been proposed that indicate that the leakage current measurement resulting from the high-frequency common mode component of the PWM inverter output voltage is used for the purposes of monitoring capacitance and dissipation factor; and [106], in which preinstalled current sensors detect microscopic changes that appear in their signals, and a method is proposed that quantifies these changes by machine learning. ...

Reference:

Insulation Life Span of Low-Voltage Electric Motors—A Survey

... The separation of conducted CM and DM emissions is a widely known practice during EMI pre-compliance testing [12] and has been discussed extensively in literature. Especially for single-phase systems, there exist various implementations, either comprising passive components [7], [13]- [19], power splitters [20], active components [21] or using computer-aided design with post-processing [22], [23]. All of the presented implementations rely on the fact, that in a single-phase system, the CM and DM components of the CE can be determined independently using the two voltages v LISN,p (noise on the phase line with respect to earth) and v LISN,n (noise on the neutral line with respect to earth) as follows (1) (2) Due to the coupling between the phases a, b and c, the determination of the CM and DM noise components in a three-phase system is not as straight forward as in the singlephase case. ...

Reference:

Design and Experimental Analysis of a Three-Phase Active CM/DM Conducted EMI Noise Separator

... This may be realized by a digital isolation integrated circuit (IC), a digital fiber optic transmission or even wireless. In [8], [9], a Bluetooth probe is shown; with this approach the cabling can be reduced, especially when there are more measurement points at the same time, e.g. measuring all 3 inverter output voltages and the dc input. ...

Reference:

A Digital Isolated High Voltage Probe for Measurements in Power Electronics