Pulse Load Applications Research Articles

Sinusoidal Input Current Discontinuous Conduction Mode Control of the VIENNA Rectifier

During light load conditions unidirectional power factor correction rectifiers, such as the VIENNA rectifier, enter discontinuous conduction mode, causing the relationship between average half-bridge voltage and duty cycle to become nonlinear and synchronously sampled current measurements not equaling the switching period average. Combined, these measurement and actuation errors result in distorted input currents at light load if no additional measures are taken. This work presents a control scheme that leads to low total harmonic distortion of the input currents in discontinuous conduction mode without relying on current measurements. The analytic expressions for the duty cycles and the threshold between discontinuous and continuous conduction mode are derived, the capability of supplying asymmetric loads is investigated and the effect on the noise spectrum relevant for the electromagnetic interference filter design is studied. Measurements of efficiency, total harmonic distortion, and conducted electromagnetic interference in discontinuous and continuous conduction mode are obtained on a 65 kW prototype operating at 290 to 530 V line-to-line RMS mains voltage range and supplying 800 V dc output voltage. The prototype, which is optimized for pulse load applications, achieves a power density of 9.56 kW/dm3 (157 W/in3) and 97.2 % efficiency at full load using 650 V Si insulated gate bipolar transistor (IGBTs) with 28 kHz switching frequency.

25-kW Three-Phase Unity Power Factor Buck–Boost Rectifier With Wide Input and Output Range for Pulse Load Applications

Pulse loads, like solid-state pulse modulators, generate short pulses with a high peak power that exceeds the average power by 100-1000 times depending on the pulse repetition rate. There, the peak power usually is drawn from an energy buffer such as a capacitor bank. The pulse discharges the energy buffer, and it is fully recharged in the time between the pulses by a power supply, which is usually connected to the mains. Due to the worldwide variation in mains voltages and the desired ability to adapt to the capacitor voltage of the modulator, the power supply has to support a wide input and output voltage range. Additionally, the supply should draw a sinusoidal current from the mains while providing energy to the pulse modulator due to electromagnetic interference regulations. Therefore, a general control concept for pulse load applications, which guarantees continuous power consumption from the mains and power factor correction, is described in this paper. Furthermore, measurements of the control principle, which is independent from the converter topology, are presented for a three-phase buck-boost rectifier.

Modeling double-layer capacitor behavior using ladder circuits

The double-layer capacitor (DLC) is a very complex device that is best represented by a distributed parameter system. Many different lumped-parameter equivalent circuits have been proposed for the DLC. An examination into utilizing a ladder circuit to model a DLC is presented. Parameters for different ladder circuits are determined from AC impedance data. Variations in circuit parameters with DC bias and manufacturing have been investigated. The performance of the ladder circuit has been evaluated in slow discharge and pulse load applications.

Using a Debye polarization cell to predict double-layer capacitor performance

Many different circuit models have been proposed for double-layer capacitors (DLCs). Presented in this paper is an evaluation of the Debye polarization cell as a model for a double-layer capacitor (DLC). In comparison to other circuit models, the primary advantage of this model is that the circuit elements can be related to chemical reactions which occur inside the DLC. The circuit element values are found from AC impedance measurements for a DLC and a computer program which utilizes a nonlinear least-squares fitting technique. Variations in circuit element values with DC bias level and manufacturing have been investigated. The performance of the Debye polarization cell in slow discharge and pulse load applications has been compared to actual circuit measurements and to simulated results using a classical equivalent circuit.

Zero-voltage-switched multiresonant converter for high-power, pulse-load applications

A full-bridge zero-voltage-switched (ZVS) multiresonant converter (MRC) was built for a pulse load with a peak power of 1.44 kW and an average power of 360 W. The converter works with an input-voltage range from 220 to 350 V, and delivers 32 V to the pulse load with a constant peak current of 45 A. The efficiency range of the converter was measured from 82.5 to 90.5%. The maximum efficiency occurs at low line and decreases as the input voltage increases. Detailed analysis and design of the converter, along with experimental results, are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>