Precision rectifier

About: Precision rectifier is a research topic. Over the lifetime, 4952 publications have been published within this topic receiving 63668 citations. The topic is also known as: super diode.

Direct power control for Neutral-point-clamped three-level PWM rectifier

Abstract: This paper proposes a direct power control (DPC) strategy employed for the neutral-point-clamped (NPC) three-level PWM rectifier. Mathematic model of NPC three-level rectifier is conducted firstly as a theoretical base. This topology generates a higher number of output voltage levels, increasing the flexibility for selecting an appropriate voltage vector. The direct instantaneous power control technique for the converter, which has been developed to control the instantaneous active and reactive power directly by selecting the optimum switching state of the converter, is discussed in detail in the paper. The neutral-point potential is controlled according to the direction of the mid-point current and a study of each switching vectorpsilas influence to active and reactive power. Theoretical analysis is presented and the performance of the proposed method is verified by simulation and experiment.

Deepwater in-situ fluorometer

Abstract: An onboard power supply and metering unit is connected, via an overboard cable e.g., 1000 meters long, to an underwater light-pulse projecting unit and a fluoroescence-sensing receiver unit. The operating power is transmitted to the underwater units by an onboard constant-current source, instead of a voltage source. Likewise, the output signal of the receiver unit is transmitted through the cable in the form of a current, not a voltage. The current of the receiver's photodiode is integrated, the peak value of the integral determined and held, this held value logarithmized, the logarithmized value sampled and held, and the held voltage converted to a current constituting the output signal. The offset of the peak detector and the input stage of the log amplifier are balanced automatically, by a balancing signal applied during pulse measurements, but derived between pulse measurements. The balancing signal is derived by integrating a signal derived from the log amplifier's output signal, and is applied to the input of the peak detector, with the peak detector converted to simple voltage-follower operation during the deriving of the balancing signal.

An improved active-front-end rectifier using model predictive control

Abstract: This paper investigates an improved active-front-end (AFE) rectifier using model predictive control. The model predictive control (MPC) algorithm utilizes the discrete behavior of the power converter to determine the appropriate switching states by defining a cost function. The performance of the AFE rectifier has been verified with 3.0 kW experimental setup which shows that the efficiency of the MPC controlled AFE-rectifier is 96.82% and is operated with acceptable THD (4.0%) of input current and very low DC voltage ripple. An efficiency comparison is performed between the MPC and VOC-based PWM controller of the AFE rectifier which ensures the effectiveness of MPC controller. Moreover, the stability of the MPC method has been analyzed with the root locus, discrete z-domain frequency response techniques (Nyquist diagram) and non-linear experimental system. The result confirms that, the control system of AFE rectifier is stable as it operates with infinite gain margin and very fast dynamic response.

Synchronous rectifier circuit

Abstract: A self-driven synchronous rectifier circuit applied to a forward converter is provided. The circuit includes a transformer having a primary winding and a secondary winding for converting an input voltage into an output voltage, a first synchronous rectifier switch and a second synchronous rectifier switch connected to the secondary winding for rectifying the output voltage; and an auxiliary switch, wherein the gate terminal thereof is connected to the gate terminal of the first synchronous rectifier switch and the positive end of the secondary winding, the source terminal thereof is connected to the drain terminal of the first synchronous rectifier switch and the negative end of the secondary winding, and the drain terminal thereof is connected to the gate terminal of the second synchronous rectifier switch.

Class E half-wave low d/spl nu//dt rectifier operating in a range of frequencies around resonance

Abstract: A Class E half-wave low d/spl nu//dt rectifier is analyzed; simulation and experimental results are given when it operates in a large range of frequencies around resonance. The diode parasitic capacitance is included in the parallel capacitance. The leads inductance and the isolation transformer leakage inductance (if any) are included in the series inductance. Simple and accurate modeling is thus possible. Equations describing the circuit operation are derived for the rectifier being driven by a sinusoidal voltage source. Theoretical, simulation and experimental results are in good agreement. >