Reliability Analysis and Fault-Tolerant Operation in a Multilevel Inverter for Industrial Application

The extensive employment of power semiconductor devices in multilevel inverters (MLIs) has the consequence of increased failure probabilities. With numerous applications demanding highly reliable inverters, several fault-tolerant schemes have been devised to address switch open-circuit faults. This paper analyzes a multilevel inverter topology for IGBT modules undergoing open-circuit faults, a major impediment to reliable operation within a power converter. Reconfiguration of modulation is performed post-fault. A modulation scheme is implemented across failure modes as a hybrid of nearest level control and selective harmonic elimination. Reliability assessment of the topology is performed, including a comparison with previous literature in terms of component requirements and reliability. Simulation results validate the proposed solutions.

Energy efficiency of power electronics converters in traction power supply networks at voltage increase

The main features of the procedure for predicting electrical losses in power semiconductor converters of AC-DC and DC-AC systems of high voltage DC traction are presented. The procedure is based on simulation of multi-cycle switching of IGBT modules in combination with simulation of static and dynamic switching losses in traction converter circuits. The models take into account the switching frequency, physical processes in the formation of voltage and current diagrams at transition processes and in the static state of the switch elements. The model of loss assessment using particular types of IGBT modules is the basis for calculating the energy efficiency characteristics of traction converters for advanced high-voltage direct current traction systems.

Inverter Volt-Ampere Capacity Reduction by Optimization of the Traction Synchronous Homopolar Motor

The synchronous homopolar motor (SHM) with an excitation winding on the stator and a toothed rotor is a good alternative to traction induction motors for hybrid mining trucks. The main problem in the design of the SHM electric drives is that the magnetic flux forms three-dimensional loops and, as a result, the lack of high-quality optimization methods, which leads to the need to overrate the installed power of the inverter. This article discusses the procedure and results of optimization of a commercially available 370 kW traction SHM using the Nelder–Mead method. The objective function is composed to mainly improve the following characteristics of the traction SHM: total motor power loss and maximum armature winding current. In addition, terms are introduced into the objective function to make it possible to limit the voltage, the loss in the excitation winding, and the maximum magnetic flux density in the non-laminated sections of the magnetic core. As a result of the optimization, the motor losses and the maximum current required by the motor from the inverter were significantly reduced. The achieved reduction in the maximum current allows the cost of the IGBT modules of the inverter to be reduced by 1.4 times (by $ 2295), and also allows the AC component of the DC-link current to be reduced by the same amount.

Optimization of Insulated Gate Bipolar Transistor System to Maximize Heat Dissipation

An electric motor, a battery and an inverter are the key components of any hybrid vehicle. The most commonly used switching device in the electric power conversion system is Insulated Gate Bipolar Transistor (IGBT) modules. Heat sinks with their fins are optimized to provide the maximum heat flow to the surrounding and Pure copper is used as it has high thermal conductivity with reasonable heat resistance. This helps to decrease the temperature of the IGBT and heat will spread to the fins. Parallel forced air cooling is utilised to give maximum possible heat removal rate. Further experimentation was done on a IGBT using an Inverter circuit and it was analyzed on ANSYS software and it was observed that the results obtained by numerical method and experimental method are approximately same.

Research on dynamic current sharing method of parallel connected IGBT modules for NPC three level converters

The parallel connection of IGBTs has been being applied in high power neutral point clamped (NPC) three level converters. This paper investigates the impact of gate parameters (gate resistor and capacitance) on dynamic current imbalance of parallel connected IGBT for NPC three level converter. A gate parameters calculation method is proposed in the paper, and the delay time and collector current difference can be analysed quantitatively. Experimental results have shown the effectiveness of the method.

Thermal Cycling in Converter IGBT Modules with Different Cooling Systems in Pitch- and Active Stall-Controlled Tidal Turbines

This paper compares active and passive cooling systems in tidal turbine power electronic converters. The comparison is based on the lifetime of the IGBT (insulated gate bipolar transistor) power modules, calculated from the accumulated fatigue due to thermal cycling. The lifetime analysis accounts for the influence of site conditions, namely turbulence and surface waves. Results indicate that active cooling results in a significant improvement in IGBT lifetime over passive cooling. However, since passive cooling systems are inherently more reliable than active systems, passive systems can present a better solution overall, provided adequate lifetime values are achieved. On another note, the influence of pitch control and active speed stall control on the IGBT lifetime was also investigated. It is shown that the IGBT modules in pitch-controlled turbines are likely to have longer lifetimes than their counterparts in active stall-controlled turbines for the same power rating. Overall, it is demonstrated that passive cooling systems can provide adequate cooling in tidal turbine converters to last longer than the typical lifetime of tidal turbines (>25 years), both for pitch-controlled and active speed stall-controlled turbines.