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The paper presents novel transformer-flux-balancing control methods for the isolated bidirectional full-bridge (FB) converter with active clamp and the bidirectional dual-active bridge (DAB) converter. Both approaches are based on the sensing and control of the transformer magnetizing current. For the isolated bidirectional FB converter the magnetizing current is obtained by sensing a single current,...
“Peak Current Mode Control” (CPM) is usually implemented in analogue and brings the advantage of cycle by cycle protection, higher bandwidth rejection of input voltage disturbance or equivalently increases a converter's input impedance. “Average Current Mode Control” (ACM) allows inductor current control to a “true average” and will facilitate an accurate current limit loop or Power Factor Correction...
This paper proposes a new topology for a pulse width modulation (PWM) rectifier which can achieves both sinusoidal input current on the ac side and ripple power decoupling on the DC side without additional switches. The AC inductor of the conventional H-bridge circuit is divided into two parts and only an auxiliary decoupling capacitor is added in the proposed circuit. Control scheme is also proposed...
This paper investigates the dc link voltage ripple in a modular multilevel converter (MMC). It is found that switching-frequency ripple occurs on the dc link voltage in MMC when circulating current suppressing control is implemented. The mechanism of the switching-frequency voltage ripple is investigated and explained. Circulating current suppressing control will manipulate the average values for...
One of the main technical challenges of the Modular Multilevel Converter (MMC) for medium-voltage adjustable-speed motor drive applications is the large magnitude of the SubModule (SM) capacitor voltage ripple under low-speed operation. This paper proposes two new techniques to reduce the magnitude of SM capacitor voltage ripple of the MMC for motor drive applications. The paper presents a comprehensive...
This paper introduces a low complexity implementation of the voltage balancing sorting algorithm to reduce the switching frequency of the power devices in modular multilevel converters (MMCs). Two modulation techniques are evaluated; staircase modulation and phase-disposition pulse-width modulation (PD-PWM) under the conventional and the proposed algorithm. Using a circulating current controller in...
This paper presents a study of a generalized multilevel asymmetric inverter based on a H-Bridge Cell with one Arm Series (CHB-as) and five switches. It is shown several asymmetrical arrangements of input source combinations that produce several equally spaced voltage levels with few components. Equations for determining the switching frequency employed in the low power processing cells are developed,...
This paper proposes the pulse width modulation (PWM) control strategy for low-speed operation in the three-level neutral-point-clamped (NPC) inverters based on the bootstrap gate drive circuit. For the purpose of the cost reduction, several papers have paid attention to the bootstrap circuit applied to the three-level NPC inverter. However, the bootstrap gate driver IC cannot generate the gate signal...
In this paper, the proposed hardware logic type digital controller for on-board SMPS which has a very small time-delay in control loop has been described. Some experimental has been done including evaluation of load current change and frequency characteristic of open loop transfer function. These results have been revealed that the proposed circuit could be suppressed the time delay to sub — micro...
In this paper a generalized multi-phase space vector theory is considered for developing the space vector modulation of a three-phase to seven-phase direct matrix converter (DMC). The modulation is based on the control of the voltage vectors in the first d-q plane, while imposing the remaining voltage vectors in the second and the third planes (x1–y1, x2–y2) zero. The duty cycles of the bidirectional...
This paper proposes a new 1200V cascaded high voltage IC (HVIC) gate drive circuit for a three-level NPC inverter intelligent power module (IPM). The proposed single-ground IGBT gate driver of the 1200V three-level NPC inverter is based on a bootstrap capacitor charging method and a cascaded 600V HVIC configuration which can dramatically improve its integration for practical use, especially system...
Special switching sequences involving division of active state time are used in space-vector-based generation of pulse width modulation (PWM) waveforms. This paper proposes a hybrid PWM technique which is a combination of the conventional and special switching sequences. The proposed hybrid PWM technique reduces the peak-to-peak torque ripple at high speeds of an induction motor drive. Supporting...
Modeling the effects of digital control and digital PWM can be complex for power converters with multiple switches and unique PWM switching schemes; hence an approach of measuring the plant and open loop response is typically followed to verify the modeling or use frequency response data to identify the plant. This paper presents a cycle efficient software frequency response analyzer (SFRA), that...
A new interleaved three-phase PFC AC-DC singlestage multilevel is proposed in this paper. The proposed converter uses a flying capacitor structure with standard phase-shift PWM to improve efficiency, particularly at light load conditions. In the paper, the operation and its steady-state characteristics are explained and its design is discussed. The feasibility of the new converter is confirmed with...
In this paper, an improved control loop based on feedforward is proposed to reduce the total harmonic distortion of the input current (THDi), realizing power factor correction (PFC) in MCM. The frequency responses of the input impedance for a wide frequency range are improved and unified by adding feedforward duty-ratio to the output of the original current-loop. A 5 kW experimental prototype is built...
This paper analyzes the stability issue of the Flyback converter which utilizes a second stage LC filtering circuit at its output side. The small signal models of the Flyback converter using second stage filter, in both DCM and CCM, are presented with experimental data collected to verify the theoretical analysis. Finally, guidelines for designing the second stage LC filter are derived to facilitate...
In solar array-battery power system of satellites, new topology and control strategy have been studied to decrease the volume and weight. In this paper, a multi-port converter with the multimode control is introduced. The control strategy for the module is proposed, which contains domain control and dual-frequency PWM control, i.e. multi-mode control strategy. It is demonstrated that dual-frequency...
The control of boost converters using traditional linear techniques features fixed switching frequency and a simple implementation. Due to its characteristic non-minimum phase behaviour, the dynamic response can be improved only to a limited extent. On the other hand, excellent dynamic performance can be achieved with boundary controllers in which the demands placed on processors and sensors are greatly...
Two AC-DC converter topologies for 3-phase utility grid interface using high frequency (HF) or medium frequency (MF) transformers have been proposed in this paper. The transformer primary side converter structure is similar in both the topologies (say T-I and T-II), but the secondary side converter structures as well as the modulation schemes are different. The line-frequency AC voltage from the utility...
This paper presents a new grid-connected delta inverter system (DIS) for large scale photovoltaic (PV) power systems. The delta inverter achieves DC to three phase AC inversion by using only three power semiconductor devices instead of six devices as in a conventional full bridge three phase inverter. This reduction in the number of switching devices contributes to higher power density for PV energy...
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