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To realise a soft-switching inverter with a simple structure, high-efficiency and low-voltage stress, a novel resonant DC-link three-phase soft-switching inverter and its load adaptive commutation control are proposed in this study. Without two bulk capacitors and coupled inductors in the commutation circuit, the analysis and calculation of the inv...
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... The different positions of auxiliary commutated circuit (ACC) is the classification standard for soft-switching inverters, which can be classified into two kinds. One kind is auxiliary resonant commutated pole inverter (ARCPI) [6][7][8][9][10][11][12][13][14] and the other kind is resonant DC-link inverter (RDCLI) [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Each phase leg of ARCPI has its own independent ACC, which implies simpler control and higher reliability. ...
... The above two problems are crucial and must be solved in future practical application of novel PRDCLI. To solve the problem of too high f ACC , the load adaptive modulation strategy based on sawtooth carrier with alternating positive and negative slopes is proposed in [28], which reduces fACC to f s , that is, the ACC merely needs to be operated once to meet the soft-switching requirements for all switches in one T s ; but the current flowing through the ACC is still the resonant current and load current together. For this, the modulation strategy with shunt dead zone is proposed in [13], but when it is applied to [28], it cannot reduce I ACC . ...
... To solve the problem of too high f ACC , the load adaptive modulation strategy based on sawtooth carrier with alternating positive and negative slopes is proposed in [28], which reduces fACC to f s , that is, the ACC merely needs to be operated once to meet the soft-switching requirements for all switches in one T s ; but the current flowing through the ACC is still the resonant current and load current together. For this, the modulation strategy with shunt dead zone is proposed in [13], but when it is applied to [28], it cannot reduce I ACC . The reason is that the reactive energy stored in the auxiliary resonant capacitor cannot be released when the bus current is commutated from reverse current to forward current. ...
To overcome the challenges of large reactive energy transmission loss and high current stress, which ocurr during the operation of auxiliary commutated circuit (ACC) of novel parallel resonant dc-link inverter (PRDCLI), an improved modulation strategy for reactive energy transmission loss is herein proposed based on the discontinuous pulsewidth modulation (DPWM), which adopts sawtooth carrier wave with alternating positive and negative slopes and shunt dead zone. Compared with the original modulation strategy, based on minimizing the ACC operation frequency, the proposed modulation strategy is able to realize all switches soft-switching, and avoid the superposition of resonant current and load current during the operation of ACC, thus, effectively reducing the reactive energy transmission loss and the current stress of auxiliary switches of the ACC. Under the proposed modulation strategy, the equivalent circuits in different operation modes are divided, and the operation principle, voltage/current stress, loss distribution, and optimal parameter design method of novel PRDCLI are researched. Eventually, the proposed modulation strategy is verified by experiments on a 5-kW/40-kHz prototype made by SiC
mosfet
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... Resonant DC-link inverters and resonant-pole inverters are two main types of soft-switching inverters. The auxiliary circuit of the resonant DC-link inverter is located in the DC link [3][4][5][6][7][8]. When the DC-link voltage periodically changes to the zero state, the main switch of the inverter completes zero-voltage soft-switching, which can reduce the switching loss, but the zero state periodically formed by the DC-link voltage can reduce the DC voltage utilisation rate of the inverter. ...
In order to optimise, the operating efficiency of the three‐phase inverter, a new three‐phase efficient resonant‐pole inverter without auxiliary switches is presented. A set of auxiliary circuits without auxiliary switches is set on each phase bridge arm. When the auxiliary circuit works in the inverter commutation process, the main switch device on the bridge arm can achieve zero‐current turn‐on and zero‐voltage turn‐off, and the efficiency of the inverter can be improved by reducing the switching loss. Furthermore, there are no auxiliary switches in the auxiliary circuit, which is conducive to limiting the hardware cost of the auxiliary circuit and improving the reliability of the inverter. This study analyses the working mode of the circuit and the realisation condition of soft switching. The experimental results on the 3 kW prototype indicate that the switching device is in the state of soft switching, and the efficiency of the prototype at the rated output power is equal to 98.9%, which is more than that of other similar soft‐switching inverters. Consequently, the presented topology is significant for the research and development of efficient three‐phase inverters.
The pre-charging process of the auxiliary circuit of the auxiliary resonant pole inverter increases the current stress of the switch and the loss of the inverter. To overcome these problems, this paper proposes an auxiliary resonant pole soft-switching inverter with low pre-charging current. In contrast to the existing auxiliary resonant pole soft-switching inverter, this inverter can effectively decrease the pre-charging current of the auxiliary circuit, thus reducing the current stress of the switch, lowering the conduction loss of the switch, and improving the inverter efficiency. Moreover, the main switch and auxiliary switch of this inverter share a common resonant capacitor, which reduces the loss resulting from reactive energy conversion of the auxiliary commutation circuit so that the inverter achieves the purpose of simplicity and efficiency. On the basis of the equivalent circuit diagram in each operating mode, the operating mechanism of this inverter is analyzed. In addition, the soft switching conditions and the parameter optimization design method of this inverter are provided. Finally, the validity of this inverter is experimentally verified.
Aiming at the problems of high current stress, large conduction loss and overly many components in the auxiliary commutated circuit (ACC) of the newly proposed parallel resonant DC link inverter (PRDCLI), this paper proposes a modulation strategy. It includes two parts: a strategy for minimizing the ACC operating frequency, and a synchronize strategy using shunt dead zone. With this new modulation strategy, the original PRDCLI is simplified to the PRDCLI with a simple structure. Compared with the original modulation strategy and PRDCLI, the proposed modulation strategy and PRDCLI can: (1) guarantee soft-switching of all switches; (2) minimize ACC operating frequency to reduce conduction loss; (3) separate load current and resonant current during ACC operation to reduce current stress; (4) delete a group of resonant circuits to reduce hardware cost. In this paper, the operation principle under the proposed modulation strategy and PRDCLI is described in detail. Its characteristics are analyzed, which include voltage/current stress, components number, and parameter design, etc. Experimentally, a general prototype (SiC MOSFET, 8kW/80kHz) is used to compare the original modulation strategy and PRDCLI, as to verify the efficacy of proposed ones.
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This article has been withdrawn as part of the withdrawal of the Proceedings of the International Conference on Emerging Trends in Materials Science, Technology and Engineering (ICMSTE2K21). Subsequent to acceptance of these Proceedings papers by the responsible Guest Editors, Dr S. Sakthivel, Dr S. Karthikeyan and Dr I. A. Palani, several serious concerns arose regarding the integrity and veracity of the conference organisation and peer-review process. After a thorough investigation, the peer-review process was confirmed to fall beneath the high standards expected by Materials Today: Proceedings.
The veracity of the conference also remains subject to serious doubt and therefore the entire Proceedings has been withdrawn in order to correct the scholarly record.
A MOSFET is often applied as the switch in medium and small power single-phase full-bridge inverters. In order to achieve efficient operation at a high switching frequency, a new efficient inverter is presented in this paper. In addition, two sets of identical auxiliary units are arranged on the two bridge arms. When the main switches need to be turned on in each switching period, the voltage across the resonant capacitor can become zero. Thus, the main switching device can achieve zero-voltage turn-on, which can eliminate the capacitive turn-on loss existing in the MOSFET and help with the efficient operation of the inverter. The working process of the auxiliary unit and the design rules of the parameters are analyzed. Experimental results indicate that the main switching device can work in the state of zero-voltage soft-switching, and that the rated efficiency in the inverter is equal to 98.9%. This is more than that of similar inverters. This topology is significant for studies on efficient single-phase full-bridge inverters with medium and small power.
In an isolated mode operation of wind power generating system (WPGS), operating voltage and frequency are affected under sudden change of load because of more transient time, higher total harmonic distortion. To minimize the effects, the WEGS should be operated with suitable controller and the inverter should be operated with required pulse width modulation (PWM) technique. In this paper, the proposed WPGS is simulated using MATLAB/Simulink with adaptive voltage controller (AVC) and load current observer (LCO) and the inverter is operating with Unified voltage Space Vector PWM (USVPWM) technique to improve the transient behaviour of the system. The same proposed system is also simulated with conventional space vector pulse width modulation (SVPWM) techniques. The simulation results will be analyzed in various load conditions. The conventional SVPWM results compared with the USVPWM results like transient time, load voltage and load current total harmonic distortion under balanced three-phase load.
A high-efficiency three-phase resonant inverter is presented to optimize the performance of the inverter. When the auxiliary resonant circuit on each phase bridge arm works in the commutation process of the inverter, the voltage across resonant capacitors in parallel with main switches will form zero state periodically. In this case, main switches can achieve zero-voltage soft-switching. Meanwhile, auxiliary switches can achieve zero-current turn on and zero-voltage turn off during the operation of the auxiliary resonant circuit. Soft-switching can reduce switching loss and make the inverter work efficiently. The novelty of the inverter mainly reflects in the simple structure of the auxiliary circuit and the simple control method of auxiliary switches. This paper analyzes the working mode of the circuit and the realization condition of soft-switching. Meanwhile, it discusses theoretical calculation of the power loss of the auxiliary circuit. The experimental results on the 3kW prototype show that switching devices work in the soft switching state. The efficiency of the prototype under the rated output power reaches 98.7%, which is higher than that of the same type of other soft-switching inverter. Therefore, the topology is valuable for the research and development of the high-performance three-phase inverter.
Although the silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) is superior to the conventional silicon (Si) insulated gate bipolar transistor in terms of switching performance, the switching losses of SiC devices increase rapidly by hard switching when the switching frequency (fsw) increase to hundreds of kilohertz (kHz). This paper proposes an auxiliary zero-voltage-transition circuit to realize zero-voltage-switching for all of the high-frequency main switches of the active neutral point clamped (ANPC) inverter based on a SiC/Si hybrid device, and zero-current-switching for all of the auxiliary switches. Through soft switching, the switching losses and anti-parallel diode reverse recovery losses of high-frequency SiC MOSFET switches can be further reduced. First, the circuit topology and the operation principle of the soft switching are detailed followed by the design procedure of the parameters. Then, the efficiencies of hard switching and soft switching ANPC inverters are compared with fsw changing from 10 to 200 kHz. To further improve the efficiency of the soft-switching inverter, two improved methods are proposed. The two proposed methods are auxiliary switches paralleling the external diode and utilizing synchronous rectification technology. Finally, a 1 kW, up to 200 kHz frequency ANPC inverter has been built to validate the above analysis.
