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Comparator is the main building block in ADC architecture. Main purpose of a comparator is to compare a signal with a reference signal and produce an output depending on whether the input signal is greater or smaller than reference. In this paper, a high speed high resolution comparator for use in sigma delta modulator is designed. The comparator is designed in a 0.35 um CMOS process with a supply...
High performance interior permanent magnet synchronous machines show nonlinear magnetics due to saturation and cross-coupling. Nonlinear differential equations describe these phenomena and make feedback control challenging. This paper presents a predictive control method to precisely control the dynamics of these machines. Four real-time capable strategies to online identify transient trajectories...
Induction motor loads form an integral part of any electrical load network and possess a unique characteristic. The high reactive power drawn from the system by motor during start up causes voltage drop which may affect other loads in the network. This drop is more pronounced in a weak microgrid, which do not have the capability to quickly compensate the drop. The only way to determine voltage drop...
This paper solves problematic of immunity of electric drive from the voltage sags on the power supply. Typical modern electric drive consist of the induction machine (or synchronous machine) supplied from indirect frequency converter with voltage-fed inverter and with non-controlled rectifier (or other - more complicated type of input side of this frequency converter). For this configuration are compared...
China Machinery Industry Standard (CMIS) GB/T 12326-2008 prescribed in the islanded operation mode, microgrid inverter (MGI) output voltage dynamic transient range is less than 10% when the resistive load is switched rapidly between 0% and 100%. The three-loop power virtual synchronous generator (VSG) control methods are commonly used in MGI units to share the loads among the parallel MGIs. However,...
In this paper, a universal voltage clamping circuit for the T-type neutral-point-clamped (TNPC) converter is introduced. It is shown that, for any TNPC implementation, the proposed voltage clamping circuit can well suppress all voltage spikes of power devices at the switching transients. Therefore, the devices can operate in a much safer region.
In this paper, two modulation strategies for a three level neutral point clamped inverter SynRM drive are compared. The inverter uses two different algorithms called Mod-1 and Mod-2 for balancing the two dc bus capacitor voltages (suppression of the neutral point voltage). These modulation strategies are of the nearest three vector (NTV) family. Mod-1 chooses certain vector states to suppress the...
The growing interests in clean and sustainable electric energy push towards increasing the interconnection of wind energy conversion systems (WECS) to utility grids. Designs of the majority of WECSs employ power electronic converters (PECs), which generally have non-linear and switched characteristics. The characteristics, operation, and control of PECs in WECSs can result in non-conventional current-voltage...
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...
Traditional microgrids have sources whose transient response is limited by process or mechanical time constants depending on the technology used. Inverter based sources provide the flexibility in designing and tuning the controller parameters so as to operate microgrid within specified constraint in voltage and frequency. For this it is imperative to investigate the effect of controller parameters...
Up to now, detection of rotor faults in inverter-fed induction motors has received very little attention. This fault is difficult to be detected, since the fault-related components are too close to the fundamental (the inverter usually operates at low slip). Moreover, classic techniques cannot be applied since steady states are not common. The causes of this type of fault are analyzed in the paper,...
Double pulse test (DPT) is a widely accepted method to evaluate the switching characteristics of semiconductor switches, including SiC devices. However, the observed switching performance of SiC devices in a PWM inverter for induction motor drives (IMD) is almost always worse than the DPT characterization, with slower switching speed, more switching losses, and more serious parasitic ringing. This...
This paper deals with the approach of analyzing the magnet design based on transient behavior of an IPMSM during switching processes in the event of malfunction for automotive applications. Depending on the maximal current increase during the transient process the needed percentage of Dysprosium for the magnet design is conducted. Switching off strategy is introduced for both Voltage-Source- and Current-Source-Inverter...
The droop controller is widely used for the parallel operation of inverters. However, the conventional droop controller has a trade-off between the power sharing and the regulations of the output voltage amplitude and frequency. In order to remove this trade-off, a new droop controller is presented in this paper. This method adopts the structure of the robust droop controller and utilizes the transient...
In this project, a Flash ADC with TIQ(Threshold Inverter Quantizer) comparator and a Wallace tree encoder is described. Both DC and transient analysis report for 3 bit ADC are included. A comparison between Wallace tree and ROM encoder is included in the project illustrating how power can be reduced using Wallace tree encoder instead of ROM encoder. The design was successfully simulated for piece-wise...
Closed-loop control and modulation of AC drives with offline computed optimized pulse patterns can be achieved by manipulating the time instants of the switching transitions. During torque steps, faults and low-voltage ride through operation, however, the transient response time is often rather slow, due to the absence of an appropriate voltage vector. By inserting additional switching transitions,...
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...
Inverters and synchronous generators in islanded microgrids exhibit poor transient load sharing where the inverter initially picks up the majority of any load step. Transient voltage and frequency droop are proposed to allow the inverter voltage and frequency to dip more during transients to improve the transient load sharing, reduce peak inverter power requirements, and allow the microgrid designer...
Rigorous mathematical formulation of digital circuits, although accurate, consumes simulation time of a circuit designer who wishes to have a quick investigation of the effect of various device parameters on the electrical response of a circuit. This paper uses simple yet efficient method to calculate the average resistance of the transistors for finding the RC time constant and thereby the transient...
Inverter connected renewable energy sources are becoming increasingly general in micro-grids. It has brought many problems and challenges to the stability and transient of the system. Traditional constant voltage and constant frequency (CVCF) method fits for many occasions, but it can't plug and play easily because it needs communication between the micro-grid controller and energy sources. Peer to...
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