Reduction of Conducted Perturbations in DC-DC Voltage Converters by a Dual Randomized PWM Scheme

Randomized Pulse Width Modulation (RPWM) deals better than Deterministic PWM (DPWM) with Electro-Magnetic Compatibility (EMC) standards for conducted Electro-Magnetic Interferences (EMI). In this paper, we propose a dual RPWM scheme for DC-DC voltage converters: the buck converter and the full bridge converter. This scheme is based on the comparison of deterministic reference signals (one signal for the buck converter and two signals for the full bridge converter) to a single triangular carrier having two randomized parameters. By using directly the randomized parameters of the carrier, a mathematical model of the Power Spectral Density (PSD) of output voltage is developed for each converter. The EMC advantage of the proposed dual randomization scheme compared to the classical simple randomization schemes is clearly highlighted by the PSD analysis and confirmed by FFT (Fast Fourier Transform) analysis of the output voltage

Optimized RPWM technique for a Variable Speed Drive using induction motor

In order to comply with Electro-Magnetic compatibility (EMC) standards for conducted Electro-Magnetic Interferences (EMI) at low frequencies and to reduce audible noise annoyances in electric machines, we propose an Optimal Random Pulse Width Modulation (ORPWM) for the control of the three-phase inverter in a Variable Speed Drive (VSD). After giving the modulating principle, a spectral analysis of output voltage shows the EMC advantage of the proposed ORPWM compared to the classical Deterministic PWM (DPWM). An application to a VSD using induction motor allows affirming that the proposed technique doesn't affect the control performances, in the other side the randomization effect is confirmed and analyzed in steady state characteristics of the motor in closed loop, which is advantageous in reducing acoustic nois

Optimized dual randomized PWM technique for reducing conducted EMI in DC-AC converters

Randomized Pulse Width Modulation (RPWM) has become a viable alternative to Deterministic PWM (DPWM). Indeed by spreading the power spectrum as a continuous noise, this new technique complies better with Electro-Magnetic Compatibility (EMC) standards for conducted Electro-Magnetic Interferences (EMI) and allows reducing the emitted acoustic noise in Variable Speed Drives (VSDs). The most popular RPWM schemes are Randomized Pulse Position Modulation (RPPM) and Randomized Carrier Frequency Modulation (RCFM). A combination of these two schemes (RCFM-RPPM) or Dual RPWM (DRPWM) has also been proposed. In this paper, we propose an Optimized Dual RPWM (ODRPWM) for the three-phase inverter. First, a modulating principle is proposed. Then, a mathematical model of Power Spectral Density (PSD) of the output voltage is developed. PSD analysis shows that the proposed scheme is more effective on spreading PSD. Moreover, this analysis reveals optimal parameters of randomization for a maximum spread of the PSD. The optimization problem is then modeled and solved using two powerful nonlinear methods: the trust region method and the simplex algorith

Enhanced complex wire fault diagnosis via integration of time domain reflectometry and particle swarm optimization with least square support vector machine

Urban power systems rely on intricate wire networks, known as the power grid, which form the essential electric infrastructure in cities. While these networks transmit electricity from power plants to consumers, they are vulnerable to faults caused by manufacturing errors and improper installation, posing risks to system integrity. Thus, accurate identification and assessment of these faults are crucial to prevent damage and maintain system reliability. The objective of this research is to present an innovative and efficient methodology for diagnosing complex wire networks through the application of time domain reflectometry (TDR) combined with the particle swarm optimization (PSO) and least squares support vector machine (LSSVM) algorithm. This research addresses the imperative need to accurately locate and assess breakage faults within wire networks, emphasizing their role in both power transmission and communication infrastructure. To model the TDR answer of a specific complex wire network, a forward model is established utilizing resistance, inductance, capacitance and conductance (RLCG) parameters and the finite difference time domain (FDTD) method. Subsequently, the PSO‐LSSVM approach is used to solve the inverse problem of localizing faults in complex wire networks. The experimental results validate the practicality of this approach in real‐world systems