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To further improve the power density of modern electric drive technologies many motor designers decide to increase the rotational speed of the motor up to several tens of thousands revolutions per minute. Along with these high frequencies of the fundamental wave of the flux density inside the laminated stator cores, the electromagnetic strain of the core and the importance of the iron losses are increasing...
The MMC operated in Current Source Mode (CSM) with branch current control shows excellent fault limiting capability. With proper design, the same capability is achieved in Voltage Source Mode (VSM). The key is combining the VSM and CSM controls and having same state variables. Seamless transition between CSM and VSM is ensured by the change of references triggered either by the user or by internal...
For real-time monitoring of the on-resistance of a power transistor, the voltage and current should be measured during the switching operation. When the voltage waveform is measured, the amplifier inside the measuring oscilloscope may be distorted if the range of the measurement channel is not set wide enough to measure both on-state and off-state voltage levels, resulting in failure to accurately...
An appropriate torque-angle selection can improve the torque-to-current ratio of a machine, the size of the converter, and provide an optimal operation of the motor. An accurate determination of the core loss will lead to a better machine design and efficiency estimation. This paper presents the torque-angle and core loss characterization of a variable-flux permanent-magnet machine. Torque-angle curves...
This paper adopts a circuit model with temperature-dependent parameter values to investigate the current unbalance risk in parallel-connected lithium-ion (Li-ion) battery cells and uses this circuit model to calculate heat dissipation. The paper first investigates use of the battery model to explain the impact of temperature on current unbalance in parallel-connected Li-ion battery cells. Experimental...
In the field of permanent magnet synchronous motor (PMSM) self-sensing control, the initial rotor position estimation is always important, for which, the rotor magnetic polarity estimation is particularly a major task. This paper presents a robust rotor polarity estimation method based on the comprehensive utility of both magnetic saturation effect and rotor angular acceleration. The method can be...
Three-phase converters are common in modern power systems in interfacing of renewable sources and for improving power quality. A three-phase converter, whether operating as an inverter or active front-end, produces a varying common-mode voltage when conventional sinusoidal PWM is used. Frequency components of the common-mode voltage are located at the switching frequency which ranges usually from...
This paper presents an FPGA-based on-line condition monitoring system integrated at gate-driver voltage level. The system uses the change of on-state voltage and thermal resistance as ageing indicators. The monitoring is realized by implementing an on-line semiconductor power loss measurement system for switching and on-state losses and a thermal model of the module. Apart from the concept, its practical...
IGBT modules suffer from ageing due to thermal and power cycling. Bond wire lift-off or solder layer degradation are the known failure mechanisms. For condition monitoring, an estimation of the junction temperature during operation is necessary. For this purpose, an analog measurement board consisting of simple components is presented. The turn-off delay time is evaluated for temperature estimation...
This paper presents a current sensor embedded in a laminated bus bar. The proposed sensor is based on the Rogowski coil principle and it can detect the magnetic flux corresponding to a derivative waveform of the current within the bus bars. The frequency characteristics of the current sensor including the parasitic parameters depending on the circuit geometry are discussed. After the design of the...
This paper describes the design and test of a control algorithm for active front-end rectifiers that draw power from a residential AC grid to feed heat pump loads. The control algorithm is able to control the phase to neutral or phase to phase RMS voltages at the point of common coupling. The voltage control was evaluated with either active or reactive independent phase load current control. The control...
The previous proposed method for thermal network parameter identification of IGBT module in [1] is based on the pre-knowledge of heat sink's thermal parameter, which neglected the aging effect of heat sink. This paper improved the identification method in [1] and make the improved method be applicable to systems without acknowledge of heat sink's thermal parameter. The theoretical analysis got the...
Grid connected Voltage Source Converters (VSCs) with LCL filters usually have voltage measurements at the filter capacitors, while it can be important to control the active or reactive power injection at the grid-side of the LCL filter, for instance at a Point of Common Coupling (PCC). Synchronization to the PCC voltage can be obtained by Virtual Flux (VF) estimation, which can also allow for voltage...
Newly developed 15 kV silicon carbide (SiC) power MOSFETs with fast switching capability enable the reduction of size, weight and complexity of medium voltage power converters. In medium voltage and high frequency applications, zero voltage switching (ZVS) is necessary since significant amount of energy is stored in MOSFETs' parasitic output capacitors. Recovering these energy is important for high...
This paper proposes a novel current/voltage sensor fault detection and isolation (FDI) method for wind energy conversion systems (WECSs) based on the power balance principle. The proposed method uses the sensor-measured signals to calculate the imbalanced power in the power converters of a WECS, which is then used as the indicator for sensor fault detection. The fault isolation process is started...
Temperature measurement of semiconductor components is essential, in particular to evaluate performances and to propose health monitoring of power modules. ThermoSensitive Electrical Parameters (TSEPs) are widely used to estimate a representative temperature of these components, mainly in non-operating conditions, different from the real environment of the latter (offline measurements). Nevertheless,...
In this paper, an analysis into the wireless power transfer system using inductive coupling with multiple transmitters and single receiver is presented. It is proved that, with certain total amount of input power from all of the transmitters, there is a maximal output power that can be delivered to the receiver. To achieve this optimal result, the electrical currents in all the transmitters shall...
To support the integration of more PV sources with utility grids, there is a need for low cost and efficient power electronics converters. In this paper, the structure of cross-switch multilevel inverter (CRM) is proposed to interface more than one PV modules with a resonant converter. CRMs treat each pair of PV modules as one unit during the positive and negative half cycles and this could go against...
Current analysis has been widely employed in academy and industry for the diagnosis of rotor damages in cage induction motors. The conventional approach based on the FFT analysis of steady-state current (MCSA) has been recently complemented with the development of alternative techniques that rely on the time-frequency analysis of transient quantities of the machine. These techniques may bring important...
Nowadays, latest advancements in power electronics have devised new ways to optimise power systems by reducing power losses. These developments provide convenience for private power producers to harness renewable energy and allow injection of optimised reactive currents to compensate for the reactive power drawn from the grid. This paper presents the development of an efficient laboratory based system...
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