Wide-band Current Sensors Research Articles

DC Series Arc Fault Detection Method in Photovoltaic System Based on Multiple Frequency Selections for Common-Mode Conductive Voltage

DC series arc faults are one of the main causes of fire hazards in photovoltaic power systems. The common method of the traditional dc series arc fault detection uses wideband current sensors to obtain the arc current signal, extract arc characteristic frequency components, and make intelligent judgments based on numerous samples. This kind of detection method requires high-performance hardware and has a high cost. This article takes the common-mode conductive voltage (CMCV) signal, which is produced by arc faults, as the object and confirms the feature frequency band of the arc CMCV signal based on the spectral analysis. To obtain the feature frequency component and perform frequency reduction at the hardware level, multiple frequency selection and detection circuits were designed, and the feature quantities of the time and frequency domains were extracted from the output of the circuits. Subsequently, a two-dimensional arc fault feature plane was constructed, and an arc/normal similarity criterion and arc fault judgment algorithm were proposed. Finally, this article discusses or experimentally verifies the effectiveness, reliability, and anti-interference ability of the proposed method. The proposed method is low cost, simple, reliable, and effective and provides a novel idea and approach for dc series arc fault detection.

Cascoded GaN half-bridge with 17 MHz wide-band galvanically isolated current sensor

A cascoded GaN half-bridge with a wide-band galvanically isolated current sensor is proposed. A 650 V depletion-mode GaN field-effect transistor is switched by a low-propagation-delay gate driver in active-mode. The standby and active modes are switched by a 25 V N-ch laterally diffused MOS (LDMOS). The current sensor uses the LDMOS as a shunt resistor, gm-cell-based sense amplifier and a mixer-based isolation amplifier for wider bandwidth. PVT variations of on-resistance of the current-detecting MOSFET are compensated using a reference MOSFET. A digital calibration loop across the isolation is formed to keep the current sensor gain constant within % across the whole temperature range. The wide-band current sensor can measure the power device switching current. In this study, a cascoded GaN half-bridge switching and inductor current sensing using low-side and high-side device current are demonstrated. The proposed techniques show the possibility of implementing a GaN half-bridge module with an isolated current sensor in a package.

A Non-Invasive DC-10-MHz Wideband Current Sensor for Ultra-Fast Current Sensing in High-Frequency Power Electronic Converters

To enhance the performance of the converters along with improving their efficiency and miniaturization in many power electronics applications, a need for higher switching frequency is highly demanded. In high switching frequency converters, due to high common mode voltage issue, wideband, isolated, and low loss current sensor is required for the robust control design and ultra-fast protection. In this paper, we propose a non-invasive hybrid, isolated, and loss-less wideband current sensing method applicable for high-frequency power converters (dc-10 MHz). The proposed hybrid current sensing scheme combines two different isolated sensing technologies—a magnetoresistor sensor and a differential Rogowski coil sensor, which have complementary characteristics to achieve a wide sensing bandwidth. The proposed hybrid current sensor also utilizes planar magnetic field concentrators (MCON) using conductive materials to normalize the non-uniform magnetic field distributions generated by the current over a wide frequency range. We demonstrate through hardware prototypes and experiments that the proposed hybrid sensor yields to a very high sensing bandwidth of dc to 10 MHz. The performance of the proposed hybrid sensor is also evaluated in a 1-MHz dc–dc converter as well as a high-frequency H-bridge inverter module.

Open-source wideband (DC to MHz range) isolated current sensor

Abstract A low-cost open-source wideband current sensor, measuring currents in a frequency range from DC to 5 MHz, is proposed. The sensor provides galvanic isolation, low insertion impedance, and can be used together with an oscilloscope as replacement for an expensive current probe, or as circuit integrated sensor, to measure currents with peak values up to 20 A. The hardware of the sensor consists of standard parts soldered on a printed circuit board; no special custom parts and/or manufacturing steps are needed to build. Applications are general measurement and laboratory use, e.g. measuring current waveforms in lab experiments. But the sensor can also be integrated in control circuits requiring measurements of time varying currents, e.g. for high speed current mode control in power electronics.

Current sensorless sliding mode control for direct current–alternating current inverter with load variations via a USDO approach

In this study, a current sensorless sliding mode control (SMC) approach is proposed for a direct current-alternating current inverter system. The SMC scheme shows advantages in dealing with matched disturbances and model uncertainties. However, it fails to remove the effects of mismatched disturbances. In distributed generation systems, wide range of load variations and effects of non-linear loads result in performance degradation. Load disturbances, as the mismatched disturbances, entry the system via a channel different from the control input. Load variations are coupled with the output voltage, resulting in periodic disturbances. Meanwhile, the cost increases significantly due to the requirement of wideband current sensors. In the existing current sensorless approaches, observers are designed to reconstruct current without considering disturbances. Addressing it, a novel universal state and disturbance observer (USDO) is developed to reconstruct the inductor current and load disturbances. By integrating the estimations into the design of sliding surface, a current sensorless sliding mode controller is proposed. Rigorous stability analysis for the closed-loop system is presented. Furthermore, considering higher-order harmonics, the baseline USDO is extended to reject these harmonics. Experimental results are illustrated to verify the effectiveness of the proposed scheme.