A high frequency dual-buck full-bridge inverter for small power renewable energy application is proposed in this paper. A switching frequency of 400 kHz is achieved with the adoption of the SiC power device. A two-pole two-zero (2P2Z) compensator is employed in the outer voltage loop to generate the current reference for inner current loop. A 3P3Z compensator is adopted in the inner current loop to track the current reference. A systematic way for calculating the losses of high frequency

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... r is presented, and the losses of the components are thoroughly analyzed. The turn-on and turn-off procedures of the inverter are discussed in detail. The losses caused by high frequency are calculated accurately, and the loss distribution is established as well. The procedure of the loss analysis gives a practical example for calculating the loss of similar type inverters. Moreover, deviation between pulse width modulation (PWM) control signal and switching response in high frequency switching is thoroughly analyzed. The influence of deviation is verified by designed experiment. Hence, a compensation method is proposed in order to minimize the influence. The compensation effect is validated by experiment and simulation. Finally, a 1-kW prototype is built to verify the feasibility of the theoretical analyses. The grid-connected maximum output power experiment is completed at 1 kW with the efficiency of 96.1% and the total harmonic distortion (THD) of 1.8%. The comparison experiments of power loss between Si and SiC power devices are carried out. The experiment results confirm the loss calculation method to be valid. Energies 2017, 10, 311 2 of 18 T-Type inverter in [6] . Switching performance and efficiency performance are analyzed among Si, SiC and GaN HEMT. The results demonstrate the advantage of the wide band gap power devices in high frequency inverting. It can be seen that all these inverters adopt the wide band gap power devices and have a working frequency, which is much higher than the traditional ones. As a result, the THD of the inverters is significantly reduced and the output power quality is improved obviously. Meanwhile, smaller components can be used and the volume of the inverter is significantly decreased, which broaden the application range of the inverter. On the other hand, as frequency increases, the losses of the inverter under high frequency circumstances become a major problem, which is not discussed in detail in this paper. With the application of high frequency switching, loss analysis is even more important, because it can offer a guideline for the system efficiency improvement [7] [8] [9] [10] [11] [12] [13] [14] . In [7], a detailed investigation into loss distribution for diverse components is conducted, which includes losses of switches, diodes, inductors and capacitors. In [8, 9] , the switch and diode losses of several inverter topologies are studied and compared, which gives an evident insight into the loss distribution for each low-frequency topology. Nevertheless, this comparison may show less accuracy when it comes to high frequency case, because more details of the switching procedure must be taken into account in the high frequency operation, which will affect the losses and are not included in this literature. In [10] , the mechanism reflecting the relation between transition characteristics and power losses is discussed. Diode losses based on traditional Si semi-conductor are analyzed as well. In [11] , comparative experiments of losses between Si and SiC power devices are carried out, which proves that the SiC devices are superior in switching speed, operating temperature and switching losses than the traditional Si. Although the loss analyses previously mentioned are very comprehensive and detailed, all these works are also based on traditional low frequency simplified method, which show less accuracy for the high frequency loss analysis. This is because some losses, overlooked in low frequency condition, may become an indispensable part of the total losses in high frequency implementation. Hence, deviations will be introduced if low frequency loss calculation method is implanted directly into the high frequency operation. Moreover, the influence of the high frequency switching is not confined to losses analysis. The impact of high frequency on the simulation model is also noteworthy. Model of the wide band gap power devices are established in [15] [16] [17] [18] [19] . A compact model of the SiC metal-oxide-semiconductor field-effect transistor (MOSFET) is built including the carrier-trap influences in [15] , the simulation results is verified by the experiments. Jun Wang et al. [16] discusses a 10-kV 4H-SiC MOSFET and key characteristics are extensively investigated. A simple behavioral SPICE model for the SiC MOSFETs is proposed to predict their realistic application prospect. The impact of nonlinear junction capacitance on switching transient is studied in [17] , and a simulation circuit for switching transient analysis is built. A dynamic model of GaN cascaded current aperture vertical electron transistor (CAVET) is established in ATLAS-SPICE-integrated simulator. The simulation model successfully models and projects the switching performance of the GaN CAVET. These simulation models are very thorough. However, most of the researches concentrate on the component level influence. The impact of high frequency switching on the output of the converter is not detailed discussed. On the other hand, the component level model is too complicated and time-consuming for converter analysis. The influence of high frequency switching on the inverter simulation model is rarely studied. In this paper, a high frequency single phase dual-buck full-bridge grid-connect inverter for small power renewable energy is proposed. The SiC components, as the power devices, are employed to achieve high switching frequency and to limit the conversion loss simultaneously. For the controller, the proposed inverter adopts a current voltage dual-loop. The 3P3Z compensator is adopted in the inner current loop in order to track the current reference which is generated by the 2P2Z compensator. The 2P2Z compensator is employed in the outer voltage loop in order to regulate the DC bus voltage by balancing the input and output power. A systematic way for calculating the losses of high switching frequency inverter is presented. The losses of each component in the inverter are thoroughly analyzed. Energies 2017, 10, 311 3 of 18 The switching procedure and the corresponding losses are discussed in detail. The high frequency losses are also taken into account during the analysis. The distribution of the losses is established based on the presented method. Moreover, the deviation between PWM control signal and switching response, which emerges in high frequency switching, is thoroughly analyzed. A designed experiment verifies the influence of deviation. Thus, a compensation method is proposed in order to minimize the influence of deviation. Experiment and simulation confirm the compensation effect. Finally, a 1-kW prototype is made and a 400 kHz switching frequency is achieved. The comparison experiments of the power losses are carried out between Si and SiC power devices to verify the loss calculation method. The results proved the loss analysis is valid. Circuit Configuration and Control Method Operation Principles The topology of the dual-buck full-bridge inverter is presented in Figure 1a . The inverter can be regarded as two individual buck converters. Buck 1 consists of S 1 , S 3 , D 1 and L i1 , connecting to the DC bus positively. Buck 2 consists of S 2 , S 4 , D 2 and L i2 , connecting to the bus negatively. The output inductors of the buck converters L i1 and L i2 constitute a LCL filter with C f , L g1 and L g2 .