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This paper introduces a methodology to model and control a single-phase tri state integrated Buck-Boost inverter suitable for low power distributed generation with the capability to operate in grid connected and island modes. The tri-state modulation is adopted in order to achieve power decoupling by means of average inductor current. This way it is possible to control the DC/AC conversion independently...
The series connection of insulated gate bipolar transistors (IGBTs) allows the operation at voltage levels higher than the rated voltage of one IGBT. However, the technology has not been widely applied due to transient voltage unbalance. Asynchronous gate drive signals, which cause series-connected IGBTs not to turn-on and turn-off at the same time, result in serious unbalanced voltage sharing. This...
To estimate the RMS value of the DC-link ripple current more accurately, a method is developed considering the reverse recovery of the anti-parallel diode in voltage source inverters (VSIs). In this paper, using the analysis of the inverter DC-link current and anti-parallel diode reverse recovery, calculations are implemented based on the SPWM technique. According to the calculations and simulation...
These days, constant on-time current mode (COTCM) control schemes are widely used in the industry VR controllers for its light load efficiency and higher BW design with simpler compensation requirement. In COTCM control, external ramp is required to be added for jittering reduction to improve the noise performance of the controller. But unfortunately, with the increment of external ramp value, although...
Unlike centralized synchronous generator (SG) in conventional power system, distributed micro-sources are parallel connected to neighbors by inverters, which are less-inertia. To improve the transient stability, inverter-based distributed generators (DG) can draw an analogy between the storage and rotor rotational kinetic energy of SG in inertia function. Instead of emulating a fixed virtual inertia,...
This work focuses on the control strategies for different configurations of Non-Isolated Hybrid Energy Storage Systems. Basic strategies are proposed, studied and compared. Parting from the standard parallel connection of bidirectional boost converter in hybrid storage systems, a comparison with alternate topologies is presented. These alternative schemes overcome the problems that arise in the original...
The impact of restarting an induction machine, while coasting, is investigated in this paper. When restarting a motor, high peaking currents and torque transients appear. As a result, possible damage to the rotor shaft could occur together with destabilising the power system which could lead to a fluctuating supply voltage levels. This paper investigates the restarting of two different efficiency...
Wide bandgap (WBG) semiconductors owing to their low loss and high switching capability, are gradually adopted in high power-density high efficiency applications, and impose new challenges from control to hardware design. In this paper, a Gallium Nitride (GaN) HEMT plus SiC diode based Vienna type rectifier is proposed to serve as the power factor correction stage for a high-density battery charger...
This paper proposes a Pulse Density Modulation (PDM) method with improved transient for high frequency converters such as Class E DC/DC or quasi-resonant boost converters. In contrast to frequency or duty cycle control, the conventional PDM control method provides high efficiency at any load when modulation frequency is low. However, efficiency drops significantly for higher modulation frequencies...
Second-Order Generalized Integrator based Quadrature Signal Generator (SOGI-QSG) has been widely used in single-or three-phase power converter systems due to its simplicity and flexibility. However, its dynamic response is not only decided by its damping gain but also influenced by the input-signal parameters, especially when a fast response is required for usages such as grid synchronization. As...
A 1200 V SiC MOSFET switches at much faster rate compared to a Si IGBT. As a consequence, SiC MOSFET experiences comparatively more ringing in device voltage and current due to the presence of parasitic inductance in the converter layout. Therefore, it is not straightforward to retrofit SiC MOSFETs in the converter layout of IGBTs where parasitic inductance appears in the range of 100 nH to 300 nH...
The two-stage 48V-12V-1.8V Voltage Regulator Module (VRM) structure is gaining more and more attention in high-end server applications. The LLC converter is the preferred choice for the first conversion stage because it provides the isolated 12V output efficiently, which is then converted to 1.8V by the multi-phase Buck converter. Since the CPU works in sleep-mode most of the time, the light load...
The significant losses in the end components due to the leakage magnetic field excited by the armature and field end windings can result in partial overheating and is an important consideration in the design of large synchronous generators. This paper describes an approach based on the three-dimensional (3D) transient finite element analysis (FEA) to determine the fields and losses in the generator...
A maximum-power-point tracking (MPPT) algorithm is essential in all controllers of solar power electronic converters due to the nonlinear current-voltage characteristics of a photovoltaic generator. One of the most widely utilized algorithms are perturbative MPPT techniques such as perturb and observe and incremental conductance methods due to their simple implementation with relatively good tracking...
Current analysis has been widely employed in academy and industry for the diagnosis of rotor damages in cage induction motors. The conventional approach based on the FFT analysis of steady-state current (MCSA) has been recently complemented with the development of alternative techniques that rely on the time-frequency analysis of transient quantities of the machine. These techniques may bring important...
With the fast-switching devices like GaN HEMT applying in power converters, the converters achieve higher switching frequency, higher efficiency and higher power density. As a result of the fast switching edge and high commutation speed, the issues like electromagnetic interference (EMI), overvoltage, gate protection become daunting tasks. The active gate control technique has been verified on the...
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