Reduce Switching Losses Research Articles

Field-programmable gate array-based field-oriented control for permanent magnet synchronous motor drive

Permanent magnet synchronous motor (PMSM) is a special type of synchronous electric motor that has many applications such as in the manufacturing industry of robots, self-propelled mechanisms, in the medical fiel. In this paper, the permanent magnet synchronous motor motor control structure according to the field-oriented control (FOC) algorithm will be implemented on the field-programmable gate array (FPGA) card. Function blocks in FOC algorithm for example PI controller, space vector pulse width modulation (SVPWM) algorithm will be integrated into individual itegrated circuit (Ics) then will be connected to form an IC with the function of implementing FOC algorithm. Furthermore, this algorithm will be used for powertrains using gallium nitride (GaN). GaN technology provides switching frequencies up to 100 kHz instead of the upper 2 to 20 kHz like insulated gate bipolar transistor (IGBT) transistors. With GaN technology, it is possible to reduce switching losses as well as increase the efficiency of the power converter. The performance results will be verified through the typhoon hardware in the loop (HIL) device.

Switching Loss Reduction Method for Instantaneous Reactive Power Compensator in Three-Phase Rectifier System

This article discusses a switching loss reduction method for an instantaneous reactive power compensator (IRPC) of a rectifier system that consists of a three-phase synchronous rectifier and a buck converter. The compensator generates a compensating current to suppress the instantaneous reactive power produced by the rectifier, resulting in a sinusoidal three-phase grid current. Zero-voltage switching (ZVS) and discontinuous pulsewidth modulation are used to reduce the switching power loss caused by the high peak of the compensating current in the compensator. A new dead-time compensation method is developed based on switching current estimation to reduce the harmonic distortion of the grid current. A 4.5-kW experimental setup was used to verify the effectiveness of the proposed methods. These methods are found to improve the grid current with a total harmonic distortion (THD) of around 3% and a peak efficiency of 99.2%.

A Novel Dead Time Design Method for Full-Bridge LLC Resonant Converters with SiC Semiconductors

As third-generation semiconductors become commercial, SiC semiconductors are gradually becoming more widely used in LLC resonant converters. The efficiency of the LLC resonant converter is improved by employing soft switching. However, when designing LLC resonant converters, semiconductors are usually regarded as ideal devices, and their turn-on and turn-off times are neglected. Furthermore, the method of designing the dead time relies on engineering experience and lacks precise theoretical foundations. In order to overcome the shortcomings of the current empirical method and to improve the generality and practicality of the dead time design method, a novel method for calculating the dead time of full-bridge LLC converters is proposed through theoretical research based on the operating principle of full-bridge LLC converters and the conditions for implementing soft switching. The method takes into account the switching characteristics of semiconductors and the on-state delay time of their body diodes, stray inductance, drive circuits, and errors arising from the first harmonic approximation (FHA) and improves the accuracy of the dead time calculation. It can implement good soft switching with full-bridge LLC converters, reduce switching losses, and improve system efficiency. Finally, the simulation experiment and the 2 kW experimental prototype are built to verify the effectiveness of the proposed method.

Enabling the use of lower current-rated SiC MOSFET devices in large-current power converters by paralleling multiple H-bridges in the sub-modules

This paper presents a new sub-module topology constructed by multiple parallel-connected SiC MOSFET H-bridges. Apart from the advantage of achieving high voltage applications with low voltage-rated devices as in conventional sub-modules in modular multilevel converters, the proposed multiple H-Bridge submodule also provides the freedom of degree in current rating. The structure and the operation principle of the proposed topology are introduced first, and followed by a detailed low-level control algorithm aimed at solving the unequal steady-state current issue resulting from on-state resistance mismatches of paralleled discrete SiC MOSFETs. A modular multilevel STATCOM model constructed by multiple H-Bridge submodules is built in MATLAB/Simulink. Simulation results show: 1) multiple H-bridge submodules not only allow active current sharing of SiC MOSFET devices without the requirement of auxiliary chokes or capacitors, but also allow voltage balancing of sub-module capacitors; 2) the proposed topology allows the same converter rating to be achieved with half the amount of submodules operating at approximately three times of PWM frequency, compared with Si IGBT submodules converter, while providing 40% power loss reduction; 3) the decoupled conduction paths of paralleled H-bridges see approximately 14.8 % switching loss reduction compare with conventional paralleled SiC MOSFET full bridge sub-module.

Investigation of metal amorphous nanocomposite soft magnetic alloys in the (FexNiyCo100−x-y)80B14Nb4Si2 system

Following reports of attractive soft magnetic performance of an (Fe70Ni30)80B14Nb4Si2 alloy [1–3], improvement to this alloy is sought through substitution of small percentages of Co for Fe and/or Ni. Fifteen alloys in the (FexNiyCo100−x-y)80B14Nb4Si2 alloy system are fabricated by small batch planar flow casting and analyzed for various properties relating to their soft magnetic performance. Alloys synthesized are within the range x = 60–70 and y = 20–30. The most important properties studied here are saturation induction (Bsat), coercivity (Hc), saturation magnetostriction (λs), and Curie temperature (Tc). These metrics are important to various aspects of electric motor design. High Tc improves a material’s magnetic performance at elevated temperature, while lower Hc and λs reduce switching losses and larger Bsat is associated with higher torque capability. The resulting alloys have improved amorphous phase Tc of up to 414 ℃ and a λs reduction of up to 40%. This is achieved while keeping Hc of many compositions below 10 A/m and a calculated Bsat at T= 0 K of one alloy over 1.5 T. Given their improvements in the relevant properties, these new alloys present promise as soft magnets for electric motor applications.

Comprehensive Predictive Control Model for a Three-Phase Four-Legged Inverter

This paper presents a comprehensive model predictive control (CMPC) method to control a three-phase four-legged inverter (TP4LI) for PV systems. The proposed TP4LI model aims to predictively model and control switching frequency and higher voltage/current switching to reduce losses. The CMPC model can be operated in four modes, namely standard MPC mode (Mode I), switching frequency reduction (SFR) mode (Mode II), high voltage/current switching loss reduction (SLR) mode (Mode III), and SFR plus SLR mode (Mode IV, a combination of Modes II and III). The proposed CMPC approach controls the TP4LI to (1) successfully track balanced and unbalanced reference currents with balanced or unbalanced loads; (2) reduce switching losses; and (3) keep the generated current total harmonic distortion (THD) within the industry’s recommended limits. The TP4LI model with the CMPC approach was verified and validated in the MATLAB/Simulink for a PV system. The simulation results show good tracking and performance of the TP4LI for balanced and unbalanced reference currents with balanced and unbalanced loads in all four modes of operation.

A novel PWM technique for reduced switch count multilevel inverter in renewable power applications

This paper described a novel pulse width modulation (PWM) technique in reduced switch count multilevel inverter (MLI) for renewable power applications. Therefore, the proposed technique finds a better solution in the multilevel inverters used for improving power quality, efficiency and reduction of switching and conduction losses. It produces a smoother sinusoidal output waveform with reduced total harmonic distortion (THD) using different modulation technique. The novel PWM technique consists of nearest level control (NLC) and level shift pulse width modulation (LSPWM). Normally semiconducting devices are added for increasing number of levels. It affects the power quality and efficiency due to losses. In this work, MLI topology with reduced number of switches count for NLC and LSPWM is presented. The single-phase and three-phase inverter configuration is used in proposed mythology. Detailed simulation results for 7-level inverter of single and three-phase inverters are presented in this paper. It is observed that NLC method is better efficiency and reduced THD than LSPWM for better utilization in renewable power applications.

Research on Optimization SVPWM Method of Nine-switch Inverter for Bearingless Motor Based on Reducing Switching Times

The traditional bearingless motor system controlled by two three-phase inverters has a high cost and volume. In this paper, the nine-switch converter is applied to the bearingless motor control system, which can control the torque winding and suspension winding of the bearingless motor at the same time to save three MOSFETs. This paper proposes a nine-switch inverter SVPWM method to reduce switching loss. This method is no longer limited to only considering the action sequence of voltage vectors but reduces the switching number from selecting voltage vectors. The optimal nine-switch inverter basic voltage vector selection principle is determined by comparing the switching times of each sector combination with different voltage vector combinations. Finally, the simulation results verify the effectiveness of this method.

Control of Regenerative CHB Motor Drives at Fundamental Switching Frequency

To handle the high-power regeneration power in coal and mine industry applications, the regenerative version of the cascaded H-bridge (CHB) drives is made possible by replacing the diode-front-end rectifier with a three-phase IGBT-based active-front-end (AFE) rectifier in each power cell. However, the IGBT switching devices introduce extra switching losses to the system that must be properly handled due to the thermal constraints in high power medium voltage drive applications. In this article, a novel fundamental switching frequency control strategy is proposed for the AFEs in the regenerative CHB drive. With the proposed control strategy, the main harmonic contents generated by the AFEs are well-reshaped at a low-order harmonics range which can be further eliminated by the existing front-end phase-shifting transformer. This allows accomplishing the meeting of the IEEE std 519-2014 at the fundamental switching frequency <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sw</sub> = 60. Moreover, with the proposed switching pattern, IGBTs can be turned <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> at zero current and therefore it can reduce switching losses simultaneously. The feasibility of the proposed control strategy is verified by experimental results on a seven-level regenerative CHB drive, which can be extended to regenerative CHB drives with any voltage levels.

Hardware Design and Implementation of FPGA Controlled Seven-Level Reduced Switch MLI

The paper proposes the design of a seven-level reduced switch multi-level inverter (7LRS-MLI) topology. The design produces a seven-level staircase output waveform with fewer components (seven power switches), thus reducing the cost and area and improving the performance of the design, i.e. increasing efficiency and reducing switching loss effectively. Both symmetric and asymmetric configurations have been implemented and the results are discussed in the paper. A comparison of the proposed structure with other recent seven-level structures has been illustrated. The simulation (using MATLAB/SIMULINK software) and experimental validation of 7LRS-MLI also have been performed for R, RL load, change in load and change in a modulation index (MI). Field programmable gate arrays (FPGA) have been used for digital implementation of the switching waveforms which reduces design time and improves flexibility. For switching devices, the alternative phase opposite disposition pulse width modulation (APOD-PWM) technique is used at 500 Hz and 5 kHz. The voltage and current total harmonic distortion (THD) profiles are also computed during the simulation and experimental validation.

Long Life Power Factor Corrected LED Driver with Capacitive Energy Mechanism for Street Light Applications

Conventional switch-mode LED drivers have problems such as poor performance in harmonic distortion, flickering, power factor correction, stresses on the switches, high switching losses, large size, and high cost. To resolve these problems, we propose a long-life LED driver with the ability of power factor correction. The proposed system is based on the integration of a half-bridge LLC resonant converter and two boundary-conducted boost converters. Both boost converters share a common inductor designed in such a way that both boost converters work in boundary conduction mode to attain the natural power factor correction. Half-bridge LLC resonant converter has soft switching characteristics, which assure the zero-voltage switching (ZVS) of primary-side switches and zero-current switching (ZCS) of diodes on the secondary side. This significantly reduces switching losses and improves the overall efficiency of the system. Voltage divider capacitors are used on the input side, which minimizes the bus voltages. The proposed system has two identical secondary windings with a coupled inductor to eliminate the mismatch between them, which powers two independent LED strings. The simulation of a 100-watt 240 V AC converter yields the approximate sinusoidal shape of the input current. It shows that the switches on the primary side are operated in ZVS and the diodes in ZCS. At 240-volt AC input, the efficiency is 87.4%, the total harmonics distortion (THD) is 10.98%, and the power factor (PF) is 0.98.

A SiC asymmetric cell trench MOSFET with a split gate and integrated p+-poly Si/SiC heterojunction freewheeling diode

A new SiC asymmetric cell trench metal–oxide–semiconductor field effect transistor (MOSFET) with a split gate (SG) and integrated p+-poly Si/SiC heterojunction freewheeling diode (SGHJD-TMOS) is investigated in this article. The SG structure of the SGHJD-TMOS structure can effectively reduce the gate-drain capacitance and reduce the high gate-oxide electric field. The integrated p+-poly Si/SiC heterojunction freewheeling diode substantially improves body diode characteristics and reduces switching losses without degrading the static characteristics of the device. Numerical analysis results show that, compared with the conventional asymmetric cell trench MOSFET (CA-TMOS), the high-frequency figure of merit (HF-FOM, R on,sp × Q gd,sp) is reduced by 92.5%, and the gate-oxide electric field is reduced by 75%. In addition, the forward conduction voltage drop (V F) and gate-drain charge (Q gd) are reduced from 2.90 V and 63.5 μC/cm2 in the CA-TMOS to 1.80 V and 26.1 μC/cm2 in the SGHJD-TMOS, respectively. Compared with the CA-TMOS, the turn-on loss (E on) and turn-off loss (E off) of the SGHJD-TMOS are reduced by 21.1% and 12.2%, respectively.

A strategy for improving the SHEPWM commutation speed of CSI through hybrid switches

High-power current source inverters (CSI) usually operate at a low switching frequency to reduce switching loss. To suppress low-order harmonics and simplify filter design, the selective harmonic elimination pulse width modulation (SHEPWM) technique is a feasible common modulation strategy in industrial applications. This paper proposes an operational strategy that uses an H7 current source inverter (H7-CSI) with hybrid switches to perform the SHEPWM technique. On the basis of retaining the conventional H6 inverter bridge, the commutation speed of the CSI is improved by an additional shunt-connected high-performance power switch. The proposed scheme solves the problem that the CSIs built with low-speed switches (such as GTOs) may have difficulty for implementing the setting pulse widths of null states, while further reducing the switching losses at an acceptable cost. In addition, mitigating the influence of overlap-time by optimizing the driving signal of the H6 converter bridge. Finally, simulation and experiments have verified the effectiveness of the proposed CSI scheme.

An Isolated Three-Port Power Converter with 2C3L and 2C2L Resonant Circuits

This study proposed an isolated three-port bidirectional resonant converter that combines 2C3L and 2C2L resonant circuits for application in power dispatching. The proposed converter improves the bidirectional power dispatch capabilities of conventional three-port converters and utilizes different resonant converters to complete the energy charge–discharge through ports of different voltage levels. By modulating the frequency alone, bidirectional power regulation and electrical isolation were achieved among the three ports with different voltage levels. The converter involves the use of resonance techniques to enable the power switch to perform soft switching during bidirectional power transmissions, reducing switching loss and electromagnetic interference. The system control of the circuit was a Texas Instruments TMS320F28335 microcontroller. By simulating a DC grid port with a fixed voltage of 400 V, a vehicle battery port with a variable voltage of 280–403 V, and a battery charging port with a variable voltage of 180–213 V, an experimental platform with a rated output of 3 kW was built to determine the accuracy of the proposed theoretical analysis and design method.

A novel single phase grid connected solar photovoltaic system for state of charge estimation using recurrent neural networks

ABSTRACT Renewable energy (RE) resources have reached the top-notch state in satisfying the energy demands of recent days. Solar photovoltaic (PV) is considered as a clean form of energy among the various RE resources. A novel single-phase grid-integrated solar PV system with Re-lift Luo converter with aid of a chicken swarm (CS) optimization algorithm is presented. The Re-lift Luo converter is implemented as it has maximum power density, extreme efficacy, high-voltage-gain ratio, and reduced switching losses. Since the PV output is intermittent, the output of the converter also gets varied, which will be maintained constant by implementing a proportional–integral (PI)-based closed loop control through the optimized CS algorithm. The normalized output is further applied to the grid via single-phase voltage source inverter. A battery is utilized to store the daytime’s solar energy and discharges to the grid during the night time. The monitoring of the battery’s state of charge (SoC) is performed by recurrent neural network (RNN). A PI controller achieves the real and reactive grid side power control. The novelty of the proposed work is the utilization of three control strategies such as PI, CS, and RNN in improving the overall performance of a grid connected system in improving the power quality. Proper control and analysis of the converters and battery through intelligent controllers are the major objectives of the paper. The outcome of the proposed concept reigns in the improvement of power quality and the proper estimation of SoC, which was supported by the detailed simulation and experimental studies. The proposed configuration is verified by simulation in MATLAB/Simulink and also tested in a real-time experimental setup, and the obtained results are as per the IEEE standards.

A High Efficiency Modified Forward Converter for Solar Photovoltaic Applications

In this paper, a modification of a conventional forward converter and a new mixed-stranded transformer winding technique are proposed for the development of a simple and high efficiency isolated dc-dc boost converter for solar photovoltaic applications. The conventional single switch forward converter topology is modified for simplification and elimination of losses due to the output filter components. A new mixed-stranded transformer winding technique is proposed to minimize the leakage inductance between the primary and tertiary windings for reducing losses. A pulse frequency modulation technique (PFM) is employed for reducing switching losses at low power operation. An experimental prototype of 300 W with a voltage step-up ratio of 1:12 has been built to obtain dc output voltage between 360-480 V for the dc input voltage of 30-40 V. Through the experimental results, it is shown that the converter can boost the input voltage according to the step-up ratio and exhibits a remarkably high dc-dc power conversion efficiency with a flat response curve. The average efficiency of around 95.5 % and peak efficiency of 97.6% are obtained.

Exact Feedback Linearization Control of Three-Level Boost Converters

Three-level boost dc–dc converters present several advantages in comparison with conventional boost converters, such as reduced switching losses, lower voltage ratings for the diodes and switches, and smaller size of reactive components. The topology requires three voltage levels at the output, therefore, replacing the output capacitor of the traditional boost converter with two capacitors and a midpoint. However, due to component tolerances and/or current flowing through the midpoint, output capacitors voltages become unbalanced, leading to converter malfunctioning or destruction. To overcome this issue, an exact feedback linearization control strategy is proposed, for which an implementation with minimum sensors is obtained. Analyses of its performance at different input voltages and of its robustness against component variations are included. Simulation results are provided, showing a comparison of the proposal with a conventional control strategy and its steady-state performance with nonlinear loads. The proposed control strategy was implemented in a low-cost microcontroller unit and, experimental verification is included.

Fault Tolerant Multi-Tx/Multi-Rx Inductive Power Transfer System With a Resonator Coil

This article presents a novel multi-transmitter (Tx)/multi-receiver (Rx) inductive power transfer (IPT) system. Compared with the conventional single-Tx/single-Rx systems, multi-Tx/multi-Rx topologies increase reliability and fault tolerance. However, unequal power distribution is challenging in these systems due to coupling differences, which prevents them from operating at rated power or requires overdesigned modules. This study proposes the addition of a middle-stage resonator (MSR) that balances power distribution by separating direct couplings between Tx and Rx coils. Thus, it increases reliability and fault tolerance. Direct couplings between Tx and Rx coils are avoided via the proposed coil structure, which also provides rotational symmetry. Moreover, an analytical method is proposed to avoid bifurcation, which reduces switching losses. Then, the fault tolerance analysis on multi-Tx/multi-Rx systems and optimum selection of module numbers are investigated. Finally, a 1-kW 2Tx/1MSR/4Rx prototype is established to continue operation under single-Tx, single-Rx, and double-Rx open-circuit faults.

An Improved Auxiliary Resonant Commutated Pole Inverter With Low Loss of Energy Recovery

This brief proposes an improved auxiliary resonant commutated pole inverter (ARCPI) to optimize the transmission efficiency of the inverter. During the commutation process of the inverter, main switches can acquire zero-voltage switching and auxiliary switches can acquire zero-current switching, bringing about the significant reduction of switching loss. Besides, when the resonant state suspends in each switching cycle, the surplus energy in the resonant inductor will be fed back to the energy-storage capacitor through only one auxiliary diode, making for low loss of energy recovery. This brief illustrates each working state in a switching cycle. The relative experimental waveform indicates that switches acquire soft-switching. The efficiency of the proposed inverter achieves 99.1% at rated output power. Thus, the proposed inverter can have efficiency superiority over other similar inverters.

A Novel Modulation Method Based on Model Prediction Control With Significantly Reduced Switching Loss and Current Zero-Crossing Distortion for Vienna Rectifier

Finite control set model predictive control (FCS-MPC) is widely used in rectifiers due to its fast response. When there are multiple control objectives, the optimal switching sequence is selected by minimizing the cost function with weighting factors. However, the reduction of current ripple caused by output error and switching loss is in conflict to a certain extent for FCS-MPC. In addition, when multiple objectives are controlled, the selection of weighting factor is a serious challenge. Therefore, a modulation method based on continuous control set model predictive control is proposed in this article. Two phases are clamped and one phase is modulated, which not only can significantly reduce the switching loss without increasing the computational burden, but also can control the neutral point voltage without using weighting factors. In addition, when the proposed method is adopted, current zero-crossing distortion can be suppressed over the full range of modulation index. The effectiveness of the proposed method is verified by simulation and experimental results.