Dual Inverter Topology Research Articles

Modulation Techniques and Coordinated Voltage Vector Distribution: Effects on Efficiency in Dual-Inverter Topology-Based Electric Drives

The increasing popularity of electric drives employing an isolated dual-inverter (DI) topology is motivated by their superior DC-link voltage and power utilization, fault-tolerant operation, and potential for multilevel operation. These attributes are significant in battery-powered transportation, such as electric vehicles and aviation. Given the considerable freedom in modulation and control of the DI topology, this paper researches the impact of reference voltage vector distribution between the two individual inverters. The study also evaluates the influence of two well-established asynchronous modulation strategies—Space Vector PWM (SVPWM) and Depenbrock’s Discontinuous Modulation (DPWM1). Since simulation tools nowadays play a crucial role in power electronics design and concept verification, the results are based on extensive and detailed models in Matlab/Simulink. Employing the basic field-oriented control of a 12 kW induction motor with precisely parameterized SiC switching devices for accurate loss calculation, this research reveals the possibility of significant energy savings at multiple operating points. Notably, optimal efficiency is achieved when one inverter operates up to half of the nominal speed while the other solely establishes a neutral point for the winding. Moreover, the results highlight DPWM1 as a superior strategy for the DI topology, showcasing reduced converter losses. Overall, it is shown that the system’s losses can be significantly reduced just by the design of the voltage vector distribution in the drive’s operating range and the modulation strategy selection.

Experimental Investigation of Decoupled Discontinuous PWM Strategies in Open-End Winding Induction Motor Supplied by a Common DC-Link

Currently open-end winding induction motors fed by a dual inverter (OEWIM-DI) present an innovative approach to enhance the performance of modern electric drive systems; such as electrical vehicles and electric aircraft applications. However, the dual inverter topology requires a proper switching control strategy to enable the OEWIM drive to fully achieve its performance. This work aims to investigate experimentally the impact of different Decoupled Discontinuous Pulse Width Modulation (DDPWM) control strategies on the performance of the OEWIM-DI supplied by a common DC-link. The criteria performance adopted in this study are: (i) the Total Harmonic Distortion (THD) of the current and voltage, (ii) the Zero Sequence Voltage (ZSV), (iii) the Common Mode Voltage (CMV), and (iv) the dual inverters losses. The various DDPWM control schemes for the 1.5 kW OEWIM-DI motor drive are implemented on a dSPACE 1104 board and the results are compared with the popular and widely used Space-Vector PWM (SVPWM) strategy. From the results, it can be concluded that the optimised DDPWM technique gives the best performance. This technique has reduced the CMV by one level and reduce the losses by 50% while having the same THD and ZSV obtained with the SVPWM technique.

A Dual Inverter Topology With Quasi-Isolated Power Supplies for More Electric Aircraft Applications

Open-end load system fed by the dual inverter (DI) is a promising technique for more electric aircraft (MEA) applications. Yet, two isolated power supplies preferred by the DI are hardly available in most MEAs. To address this issue, a novel DI topology with quasi-isolated power supplies is proposed in this letter. A simple nonisolated H-bridge boost converter is adopted to generate the second power supply and, moreover, to compensate for the load zero-sequence voltage generated by the DI. The operating principle and the applicability of the proposed DI topology are presented. Besides, a simple decoupled system control strategy is proposed. It is revealed that the proposed DI topology can generate a very high output voltage from the single power supply, while the load control performance is hardly affected by the zero-sequence current. This is a prominent advantage for MEA applications. The experimental results have verified the validity of the proposed topology.

Clamping Modulation Scheme for Low-Speed Operation of Three-Level Inverter Fed Induction Motor Drive With Reduced CMV

This article introduces a family of carrier-based pulse width modulation (PWM) schemes for three-level (3 L) inverter fed motor drive for low-speed operation. The proposed PWM in dual-inverter topology (DIT) simultaneously clamps two phases of each inverter throughout the fundamental cycle, which reduces the switching transition in the pole voltage and common-mode voltage (CMV). Four PWM variants in the family (i.e., PWM-1–PWM-4) are discussed and compared with conventional discontinuous PWM schemes. A mapping of the gating pulse is derived to extend the proposed PWM to a classical 3 L inverter fed star-connected motor drive. The gating pulses are generated using triangular carrier comparison with synchronous sampling. The steady-state and dynamic performances of PWM are validated both in DIT fed open-end winding induction motor (IM) drive and neutral point clamped (NPC) inverter fed star-connected IM drive. It is observed that the proposed PWM gives inherent capacitor voltage balance in the NPC topology. PWM-1 has a higher linear modulation range than conventional zero clamp PWM and leads to reduced CMV in the NPC topology. PWM-2 and PWM-3 give reduced CMV in DIT. PWM-4 has fault tolerance to single-phase open-switch and short-switch failure in DIT.

Fast diagnosis strategy for open‐circuit fault of switch devices in open‐winding PMSM system based on voltage error estimation

In the dual inverter topology of open-winding permanent magnet synchronous motor system, due to the symmetry of the topology, switch devices have high similarity in working characteristics, which undoubtedly increases the difficulty in locating faulty devices. In this paper, by analysing the difference of inverter output characteristics before and after switch devices open-circuit fault, the relationship between the inverter output voltage error and fault location is found, and a fault diagnosis strategy is proposed. In this strategy, a construction method of fault phase characteristic current and the estimation equation of inverter output-voltage error are designed. Then, the real-time diagnosis of single device fault and two devices with the same characteristics fault at the same time is realized. Since the strategy proposed in this paper does not need additional voltage sensors, it has the same applicability as the traditional current method. In addition, the diagnosis method based on voltage information reduces the diagnosis time. Besides, this method is independent of the PWM strategy and is not sensitive to the phenomena of dead time and delayed insulated gate bipolar transistors switching. Finally, experimental results demonstrate the effectiveness of the proposed fault diagnosis strategy.

A Novel Open-Circuit Fault Detection and Location for Open-End Winding PMSM Based on Differential-Mode Components

Detecting and locating the open-circuit (OC) fault of an insulated-gate bipolar transistor (IGBT) rapidly and accurately is very important to improve the security and reliability of the drive system. However, due to the symmetry of the dual-inverter topology, it is difficult to achieve fault detection for open-end winding permanent magnet synchronous motor (PMSM). Thus, this article proposes a fault diagnosis technology for open-end winding PMSM fed by a dual inverter with a common dc bus. In this method, the faulty phase and the faulty case are identified by the average value of the output of the closed-loop controller, which is used to eliminate the differential-mode current in the system. Then, the faulty phase is isolated by removing the gate signals. Finally, the faulty IGBT is located by restructuring the faulty phase and analyzing the current of the faulty phase. In this method, the OC fault can be detected and the faulty IGBT can be located accurately. Experimental results are shown to validate the proposed detection method.

Phase Current Reconstruction of Open-Winding Synchronous Reluctance Motor Based on Edge-Alignment and Phase-Shift Strategy

This article proposes a phase current reconstruction strategy for open-winding synchronous reluctance motor (OW-SynRM) drives with the dual-inverter topology and common dc bus. The traditional reconstruction strategy cannot be applied in OW motor drives because the dual-inverter modulation and zero-sequence current suppression strategies complicate the vector combinations and shorten their durations. Besides, additional sampling is required because the sum of the three-phase current is not zero. To solve these issues, the edge alignment algorithm is proposed to extend the duration of certain vector combinations, and the phase-shift strategy for the third sampling is proposed to obtain extra current information. In the case of the reconstruction failure in immeasurable regions, the corresponding compensation strategy is investigated. With the proposed reconstruction strategy, the system cost can be significantly reduced and the reliability can be improved, where only one current sensor is required. Besides, the single sensor can be reused for power detection and protection for the whole system by selective installation. Moreover, the proposed strategy is compatible with both the 180° and 120° assignment schemes, increasing the flexibility of application. Finally, experiments are carried out on an OW-SynRM to verify the high accuracy and feasibility of the proposed strategy.

Single-Stage Hybrid Energy Storage Integration in Electric Vehicles Using Vector Controlled Power Sharing

The dual inverter topology driving an open-winding motor is well known in high voltage motor drive applications. This structure allows two energy sources to be directly connected to an open-winding motor. This enables the integration of supercapacitors into a battery electric vehicle (EV). Unlike existing solutions, this article demonstrates dynamic power sharing between the dual energy sources by controlling the active and reactive voltages of the twin inverters, thus enabling the use of the supercapacitor for either active power assist and/or reactive power assist. The dedicated vector-controlled power sharing method and energy management is shown to achieve power sharing in the dual inverter drive integrating a battery and supercapacitor, thereby eliminating the need for an additional cascaded dc/dc converter to extract/supply energy to the supercapacitor. It also enables improved efficiency by eliminating switching losses in the supercapacitor inverter during low power operation. The proposed voltage vector splitting method is also shown to achieve battery-to-supercapacitor power exchange for regulating the net energy in the supercapacitor without affecting motor operation. A laboratory prototype utilizing a 110-kW liquid-cooled EV motor and supercapacitor bank is developed to verify the practical implementation of the power and energy management strategy.

Comparison and optimisation of three‐level neutral point clamped dual output inverter

Multi-level inverter gives low total harmonic distortion when compared to the two-level inverter. A huge number of switches are required to enhance the performance of multi-level inverters. Conventional neutral point clamped (NPC) three-level inverter needs 12 switches to control a single three-phase load. In this research, dual input and output reduced switch count three-level inverter topology with a minimum number of switches is proposed to reduce the system cost, weight and driver circuits. The sinusoidal pulse width modulation (SPWM) control techniques are developed to control NPC dual inverters. The dual inverter with constant frequency and variable frequency mode are simulated by MATLAB Simulink software and the results are discussed in detail. The analysis plan with 15 different combinations of input parameters is developed as per the Box–Behnken method and the results are compared and discussed. Also, the results such as output voltage, VTHD, ITHD and efficiency are analysed by regression analysis and the derived regression equations can be used to predict the output parameters. The combination of input parameters and dual inverter topology, which give optimum output values are identified by composite desirability analysis. This dual inverter reduced switch count topology can be used for renewable energy applications to reduce the inverter cost and space.

Integrated Battery Charger for Electric Vehicles Based on a Dual-Inverter Drive and a Three-Phase Current Rectifier

This paper presents a new three-phase battery charger integrated with the propulsion system of an electric vehicle. The propulsion system consists of a dual-inverter topology connected to an induction motor via open windings. The electrical vehicles (EV) batteries are divided by two inverters. This will result in a drive with multilevel characteristics reducing the total harmonic distortion (THD) of the voltage applied to the motor. The modularity of the multilevel inverter will be maintained since two classical three-phase inverters are used. The charger will be fed by a three-phase high power factor current source rectifier. The motor windings will take the role of the DC-inductor required by the rectifier. In this way, an intermediate storage element between the grid and the batteries of the vehicle exist. For the control system of the battery charger, we propose the use of the instantaneous power theory and a sliding mode controller for the three-phase charger input currents. Finally, to verify the behavior and characteristics of the proposed integrated battery charger and control system, several tests are be presented.

Discontinuous decoupled SVPWM schemes for a four‐level open‐end winding induction motor drive with waveform symmetries

A four-level open-end winding induction motor drive (OEWIMD) is realised by feeding the open stator windings of a three-phase induction motor from either end with two-level voltage source inverters (VSIs). These VSIs are operated with unequal DC-link voltages, which are in the ratio of 2:1. This circuit configuration has the disadvantage of overcharging the DC-link capacitor of the inverter operated with the lower input voltage. Decoupled space vector pulse-width modulation (DSVPWM) schemes, which were suggested in the previous literature to circumvent this problem, result in higher switching power loss in the dual-inverter topology. It is known that the discontinuous pulse-width modulation (PWM) schemes reduce the switching power loss. However, lack of structural symmetry of the power circuit renders it unwieldy to devise these PWM schemes. This study explores the applicability of discontinuous decoupled SVPWM (DDPWM) techniques for the four-level OEWIMD, without compromising on the waveform symmetries. With the aid of an improvised loss model, it is shown that these PWM schemes achieve the reduction of the overall loss of the four-level OEWIMD compared to the DSVPWM schemes. It has also been observed that one of the proposed DDPWM schemes result in reduced dv⁄dt in the motor phase voltages.

Constant Current Fast Charging of Electric Vehicles via a DC Grid Using a Dual-Inverter Drive

Existing integrated chargers are configured to charge from single- or three-phase ac networks. With the rapid emergence of dc grids, there is growing interest in the development of high-efficiency low-cost integrated chargers interfaced with dc power outlets. This paper introduces a new integrated charger offering electric vehicle fast charging from emerging dc distribution networks. In absence of a dc grid, the charger can alternatively be fed from a simple uncontrolled rectifier. The proposed charger leverages the dual-inverter topology previously developed for high-speed drive applications. By connecting the charger inlet to the differential ends of the traction inverters, charging is enabled for a wide battery voltage range previously unattainable using an integrated charger based on the single traction drive. An 11-kW experimental setup demonstrates rapid charging using constant current control and energy balancing of dual storage media. To minimize the harmonic impact of the charger on the dc distribution network, a combination of complementary and interleaved switching methods is demonstrated.

Modeling a Grid Connected Photovoltaic System with Perturb and Observe based Maximum Power Point Tracking

This article deals with the integration study of distributed generation(DG) in the form of a photovoltaic (PV) plant in a three-phase system.Here the active power generated by the photovoltaic (PV) plant is injectedinto the grid system through a current controlled dual inverter topology.The main contribution in this article is the dual inverter topology. In thistopology, a three level inverter output is obtained which reduces the PVinjected current harmonic distortion into the grid. The control algorithmused in this article is simple and easy to implement. The PV system isoperated through a maximum power point tracking (MPPT) stage. Perturb& Observe (P&O) is the modeling approach of MPPT system operation.The system is simulated and analyzed for a different set of loads withrenewable source at different atmospheric conditions using MATLAB/Simulink tool. The grid current becomes sinusoidal with three levelsinverter and compared to existing three levels methods the dual invertermethod is simple and easy to implement.

Modeling a Grid Connected Photovoltaic System with Perturb and Observe based Maximum Power Point Tracking

ABSTRACTThis article deals with the integration study of distributed generation (DG) in the form of a photovoltaic (PV) plant in a three-phase system. Here the active power generated by the photovoltaic (PV) plant is injected into the grid system through a current controlled dual inverter topology. The main contribution in this article is the dual inverter topology. In this topology, a three level inverter output is obtained which reduces the PV injected current harmonic distortion into the grid. The control algorithm used in this article is simple and easy to implement. The PV system is operated through a maximum power point tracking (MPPT) stage. Perturb & Observe (P&O) is the modeling approach of MPPT system operation. The system is simulated and analyzed for a different set of loads with renewable source at different atmospheric conditions using MATLAB/Simulink tool. The grid current becomes sinusoidal with three levels inverter and compared to existing three levels methods the dual inverter method is...

A Dual Inverter-Based Supercapacitor Direct Integration Scheme for Wind Energy Conversion Systems

Interfacing converters used in connecting energy storage systems like supercapacitors and battery banks to wind power systems introduce additional cost and power losses. This paper therefore presents a direct integration scheme for supercapacitors used in mitigating short-term power fluctuations in wind power systems. This scheme uses a dual inverter topology for both grid connection and interfacing a supercapacitor bank. The main inverter of the dual inverter system is powered by the rectified output of a wind turbine-coupled permanent-magnet synchronous generator. The auxiliary inverter is directly connected to the supercapacitor bank. With this approach, an interfacing converter is not required, and there are no associated costs and power losses incurred. The operation of the proposed system is discussed in detail. Simulation and experimental results are presented to verify the efficacy of the proposed system in suppressing short-term wind power fluctuations.

Design and Implementation of Single Leg Reduce Switch Count Dual Output Inverter Topology

Design and Implementation of Single Leg Reduce Switch Count Dual Output Inverter Topology