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In this paper, a novel offset-based two-level pulse width modulation (PWM) scheme for a multilevel inverter with unbalanced dc sources is presented. The offset voltage is introduced as an indispensable variable in the control model for a multilevel voltage source inverter. An expression for the inverter parameters in abc coordinates can enable the determination of the operating ranges of related voltages...
This paper presents a novel single-phase inverter with a buck-boost-type power decoupling function suitable for PV generation. The proposed buck-boost-type power decoupling circuit enables the reduction of the peak voltage at the DC bus of the PWM inverter. This enables the use of switching devices with lower voltage ratings, and the resultant switching loss and conduction loss of the PWM inverter...
This paper introduces concept of discrete control method of class E amplifier which keeps nominal operation for varying load resistance. In the proposed method, shunt capacitance and output resonant capacitance are varied electronically by setting status of switches which are connected to capacitances. Proposed method can keep nominal operation, i.e., ZVS and ZDS, both when load resistance is higher...
The aim of this paper is to present static and dynamic analyses of digital peak current mode dc-dc converter. The current detection circuit of the proposed method consists of RC integrator and comparator as the AD converter. The proposed method can detect the peak current in real time. Analyses and the transient response of proposed method are discussed in this paper. As a result, the convergence...
Recently, the use of permanent magnet (PM) motors has expanded remarkably as a result of improvements in the performance of the rare-earth PM motor. However, it is desirable to reduce the use of rare-earth materials, which are an important aspect of the high-performance PM motor, because of the high cost and the unpredictability involved in procuring such materials. The performance of motors that...
A Switched Reluctance Motor (SRM) has been designed with outer dimensions, maximum torque, operating area, and maximum efficiency identical to the rare-earth PM motor used in the Toyota Prius. However, an SRM has salient poles in the rotor; thus, additional windage loss is generated. In this paper, estimation of the windage loss of the SRM is carried out. Then, a comparison to the machine test result...
This paper proposes an improved modulated carrier control method for a continuous conduction mode (CCM) power factor correction (PFC) boost converter. The proposed method allows precise sinusoidal line current shaping for a boost PFC converter operating in CCM. This is accomplished by simply comparing the compensated modulated carrier signal with the switch current information, such that the current...
Three-level boost PFC converter has advantages of lower inductor current ripple and lower switch withstanding voltage than the boost PFC converter. Interleaved current sensorless control (ICSC) had been proposed for multiphase boost PFC converters. In this paper, ICSC is modified for current sensorless control of the three-level boost PFC converter with the asymmetric loads. The modified interleaved...
Photovoltaic (PV) inverters autonomously adjust their DC-link voltages to maximize power generation. Around sunrise or sunset, a PV inverter may operate at much lower DC-link voltage than the nominal level due to the low irradiance. The inverter would be under over-modulation if the DC-link voltage is relatively low to the grid voltage at the point of common coupling. In this paper, a series of implementation...
A higher order passive power filter (LLCL-filter) for the grid-tied inverter is becoming attractive for the industrial applications due to the possibility to reduce the cost of the copper and the magnetic material. To avoid the well-known stability problems of the LLCL-filter it is requested to use either passive or active damping methods. This paper analyzes the stability when damping is required...
High penetration of PV generation may result in serious voltage rise in the distribution power system due to reverse power flow. This paper presents a decentralized voltage control for PV inverters to mitigate voltage fluctuations. Instead of operating in MPPT (maximum power point tracking) mode, each PV inverter is able to adjust its real power and reactive power based on resistive and inductive...
A novel bridgeless interleaved boost PFC rectifier is proposed for improving power efficiency and system performance in this paper. By combining the conventional bridgeless topology and the interleaved technology, this rectifier is comprised of two interleaved boost branches without the front-end diode bridge. Each branch operates in every half-line cycle, together with the current following through...
A three-phase isolated full-bridge boost power factor correction (PFC) converter with a flyback passive auxiliary converter is presented and investigated. The PFC converter operates in discontinuous conduction mode (DCM), it can achieve zero voltage turning off for the upper switches and zero voltage turning on for the lower switches. With the adoption of the passive auxiliary converter, the voltage...
A photovoltaic (PV) string comprising multiple modules/sub-modules connected in series is well known to suffer from partial shading issues, such as decreased power generation and the occurrence of multiple power-point maxima. Although various kinds of differential power processing converters and voltage equalizers that can preclude partial-shading issues have been proposed, increases in circuit and...
This paper presents a PWM control method for a variable-voltage buck single-stage bi-directional AC/DC converter for suppressing the output voltage ripple with high power factor. The proposed method maintains minimum commutations during the control period for realizing three voltage levels close to the output reference voltage on the output of the converter which in turn reduces the voltage ripple...
In this paper, a new level up shifter with high dV/dt and negative transient voltage noise immunities is presented. The proposed level up shifter achieves high noise immunity without an increase in the delay time of high-voltage ICs (HVICs). A fabricated 1200V-class HVIC adopting the proposed level up shifter on a p-type substrate indicates a stable operation under the conditions of dV/dt noise over...
Cooperative Study Group on Standard Model Development for Power Electronics Simulations, created under the Industry Applications Society of the IEEJ (Institute of Electrical Engineers of Japan), is active to develop standard models for simulations related to power electronics. Under the study group, four working groups (WGs) have been created for different fields of simulation. Among them, Smart Grid...
Spread spectrum time domain reflectometry (SSTDR) has been applied to a live PV inverter circuit to measure impedance variations caused by natural degradation in switching devices (MOSFET), and this method was applied without altering the normal operation of the circuit. Therefore, the proposed technique is able to perform condition monitoring - the state of health of the inverter. The experimental...
This paper develops an approach for islanding detection based on measurements of the frequency dependent impedance at the point of common coupling (PCC) that exploits the presence of harmonics introduced by the electric power system (EPS) and harmonics introduced by the distributed generator (DG). The approach is new: i) an analytic model for the frequency dependent impedance is derived from the interconnection...
This paper proposes a circuit topology to draw additional dc power outputs from a dc transmission line by series-connected circuits. It is based on a conventional concept of HVDC tap but the HVDC tap is duplicated in this paper in order to reduce current fluctuations on the dc transmission line. Inversed switching pattern between the two HVDC tap results in small current fluctuation and realizes additional...
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