RC Snubber Circuit Research Articles

IMPROVEMENT OF VOLTAGE STRESS ON MOTOR CONTROL HARDWARE VIA OPTIMAL LOCATION OF RC SNUBBER CIRCUIT

While the increase in the customer failure rate in the consumer electronics sector affects the manufacturers negatively in terms of cost. It has also become one of the issues that cause customer loss and customer satisfaction. In addition to the economic losses, during the production and distribution of the spare parts and products that are changed at the customer's home due to the reliability problems experienced in the field, extra carbon emissions are released to the nature for this operation. For these reasons, it has become important to reduce the rate of customer failure. 
 With the increase in electronic components, the quality and reliability precautions that may occur in the electronic circuits, have become the subject of study today. As in many white goods products, it is advantageous to have variable speed motors in refrigerators due to energy efficiency and energy regulation issues. For this reason, the compressor of refrigerator comes to the forefront as the component that dissipates the highest power proportionally. With the use of variable speed compressors, the need for an electronic board with including power conversion and motor driving capability has arisen.
 In this paper, RC Snubber circuits have been studied in order to prevent quality problems that may occur due to high switching frequency in flyback converter topology, which is one of the DC-DC converters that provide isolation. The methods in the literature based on the location of the RC Snubber in the circuit and the determination of its related values were examined and experiments were made on the simulation program. At the same time, a test mechanism was set up on the variable speed compressor motor control card of the refrigerator and measurements were taken with the help of an oscilloscope. The measurements taken in the simulation program and the experimental environment were compared.

Modeling of High-Voltage Nonpunch-Through PIN Diode Snappy Reverse Recovery and Its Optimal Suppression Method Based on RC Snubber Circuit

The snappy reverse recovery (SRR) and failure of high-voltage nonpunch-through (NPT) PIN diodes under extreme working conditions are of great significance to the reliability evaluation of operating diodes in actual power electronic devices. In this article, the analysis of the physical mechanism of the diode SRR and the restrictions of the traditional PT-PIN diode model are made. Then, the traditional model for soft recovery is improved in order to accurately describe the diode SRR characteristics. Simulations of key dynamic performances of the established model agree well with the experimental results. Furthermore, a suppression method for diode SRR based on the optimal RC snubber circuit is proposed. A high-voltage NPT-PIN diode used in the dc−dc converter with different RC snubber circuits is simulated using the proposed diode snappy model and tested. The comparison results show good consistency between the simulated and measured voltage and current peaks and the diode SRR are suppressed effectively. The developed model and results are of much importance to the prediction of the safe operation area of the diode and to the reliability improvement of power electronic device.

Analysis and Design of an RC Snubber Circuit to Suppress False Triggering Oscillation for GaN Devices in Half-Bridge Circuits

Wide bandgap devices such as gallium nitride (GaN) devices are being widely used due to their low on -resistance and parasitic parameters that can improve system performance compared to Si mosfet s. However, these advantages mentioned above can sometimes lead to unexpected behavior in practical systems, such as false triggering oscillation. False triggering oscillation may cause overshoot, electromagnetic interference, shoot-through, and even device damage, which seriously affects the performance of the system. In this paper, an RC snubber circuit is proposed to suppress false triggering oscillation in a half-bridge circuit, and the design method of the RC parameters is proposed. The proposed oscillation suppression method is simpler, easier to implement, and more effective than the active gate driver. In addition, it can provide guidance for oscillation suppression design in high-order systems. First, the double pulse circuit is used as an example to analyze false triggering oscillation and its high-frequency equivalent circuit is obtained. Then, the RC region is established by scrutinizing the characteristic equations via a root locus method. The RC snubber circuit has better oscillation suppression effect when the RC parameters are within the region rather than outside the region. Finally, the RC region designed by the proposed method is verified by simulation and experiment results, and the proposed method indicates a substantial improvement of the switching characteristics of the controlled device at turn- off .

A Method for Optimally Designing Snubber Circuits for Buck Converter Circuits to Damp LC Resonance

A method for optimally designing RL and RC snubber circuits is presented to reduce the electromagnetic interference caused by parasitic LC resonance. The Q factor of the resonance is used as the design criteria. Optimum snubber parameters are determined analytically and uniquely by using a simplified equivalent circuit of the resonant loop and deriving an analytical formula for the Q factor as a function of the snubber parameters. The optimally designed snubbers can adequately adjust the Q factor to any design target. They can also minimize the increases in the negative effects of the snubbers, i.e., overshoot and power loss. The method was applied to RL and RC snubbers to be added to a synchronous buck converter. The effects of the snubbers were reproduced by simulation program with integrated circuit emphasis (SPICE) simulation to validate the method from the perspective of resonance damping, overshoot, and power loss. The results showed that the damping effects obtained with the optimized snubbers met the Q factor design targets. They also demonstrate that the parameters are optimum in terms of suppressing overshoot and power loss. These results indicate that the method is suitable for optimizing RL and RC snubbers to damp parasitic LC resonance.

Optimal design of RC snubber circuit for mitigating transient overvoltage on VCB via hybrid FFT/Wavelet Genetic approach

This paper presents a new approach to the analysis of the transient overvoltage (TOV) generated during switching of vacuum circuit breaker (VCB). The new technique overlaps the merits of both Fast Fourier Transform (FFT) and Wavelet Transform (WT). The new approach was applied on a real case study of a pumping station of a wastewater treatment plant located at Abu Rawash, Egypt. The pumping station is driven by induction motors. Alternative transients program (ATP) is used to simulate the selected case study. The Referential Integrity between FFT and WT analyses (RI-FFT/WT) is employed to choose the RC snubber circuit parameters (R and C). The optimal snubber circuit parameters design was determined from the hybridization between genetic algorithm (GA) and RI-FFT/WT. It is evident from the simulation results that the new hybrid GA-FFT/WT approach succeeded in the selection of the most optimal RC-snubber circuits required for the mitigation of the TOV.

RC Snubber Circuit Design for ITER PF Converter Module

The proper RC snubber circuit is of great importance to protect the thyristor against overvoltage during the turn-off process. This paper mainly presents the design of commutating over-voltage RC snubber circuit for ITER poloidal field (PF) converter module. Based on the reverse recovery transient model of the multi-parallel thyristors and commutating overvoltage circuit model, the RC snubber parameters of PF converter module are obtained by the detailed theoretical calculations, and then the simulation analysis and the commutating overvoltage test of the prototype are done to verify the RC snubber components selection, the simulation and test results show that the design of RC snubber circuit can meet the commutating overvoltage protection requirement.

Physical Model Analysis During Transient for Series-Connected HVIGBTs

Obvious differences are observed between simulation and experimental results for series-connected insulated-gate bipolar transistors (IGBTs) using current IGBT models. Here, the cause of these errors is analyzed in detail. A physical model based on more effective assumptions for a 2-D structure is proposed in this paper. The relationship between carrier concentration and lifetime is considered in the model in order to achieve an accurate description for excess carrier distribution. Testing was performed in a buck converter using series-connected non-punch-through (NPT) planar-gate 6500 V/600 A high-voltage IGBTs (HVIGBTs) at various bus voltages using an asynchronous control signal. The accuracy of HVIGBT transient model is verified by comparing experimental and simulation results in buck converters using two and three series-connected IGBTs. The function of the RC snubber circuit is also evaluated using the proposed model.

넓은 충전 범위를 갖는 전기 자동차용 급속 충전기의 고효율 운전을 위한 손실 분석

Power losses of a 1-stage DC-DC converter and 2-stage DC-DC converter are compared in this paper. A phase-shift full-bridge DC-DC converter is considered as 1-stage topology. This topology has disadvantages in the stress of rectifier diodes because of the resonance between the leakage inductor of the transformer and the junction capacitor of the rectifier diode. 2-stage topology is composed of an LLC resonant full-bridge DC-DC converter and buck converter. The LLC resonant full-bridge DC-DC converter does not need an RC snubber circuit of the rectifier diode. However, there is the drawback that the switching loss of the buck converter is large due to the hard switching operation. To reduce the switching loss of the buck converter, SiC MOSFET is used. This paper analyzes and compares power losses of two topologies considering temperature condition. The validity of the power loss analysis and calculation is verified by a PSIM simulation model.

Study of Snubber Circuits in the Voltage Source Converter Based on Series-Connected IGBTs

The DC voltage of the VSC is very high and it is necessary to connect several IGBT in series. Some snubber circuits have to be used to restrain the over-voltage of IGBTs so as to avoid its damage and the snubber circuit will increase the current stress too. The over-voltage of IGBT in the converters is studied in the paper firstly. Then, the common snubber circuits used in series-connected IGBTs are discussed and compared. A simulated model is set up in Saber to study the snubber circuit at last, the results show that the RC snubber circuit is more suitable for series-connected IGBTs.

Research on Commutating Over-Voltage Protection for High Power Converter

In the course of converter normal operation, large transient surges called commutating over-voltage may be generated internally during the commutating process of thyristor. The commutating voltage can effectively be reduced by the RC snubber circuit parallel to thyristor. In the RC snubber circuit design of high power thyristor, the reverse recovery process of thyristor must be considered in detail. Based on the analysis about reverse recovery transient of thyristor, the mathematical model of the converter thyristor reverse recovery current is created. Through the equivalent transformation of converter circuit during thyristor reverse recovery period, the analytical expressions about the relationship between commutating over-voltage and RC value are derived based on the Kirchhoff’s equation. Utilizing the analysis results, the optimal resistance and capacitance value can be selected by considering the reduction of peak over-voltage value and snubber power loss. It turns out that the proposed approach is available through the commutating over-voltage simulation and experiment results of high power converter.

Investigation of Conducted EMI in SiC JFET Inverters Using Separated Heat Sinks

This paper systematically investigates the conducted electromagnetic interference (EMI) using separated heat sinks for a silicon carbide (SiC) JFET inverter for motor drives. The inverter circuit layout is implemented with discrete SiC JFETs attached on top of the heat sink, which creates extensive capacitive couplings and moreover increases parasitic oscillations. To minimize the influence, the solution of using separated heat sinks is proposed. For better common mode performance, the high-side heat sink is grounded to avoid fast dv/dts that occur between the drain of the lower switch and the low-side heat sink. For better differential mode performance, the RC snubber circuit and ferrite beads are used to damp parasitic oscillations. Two 2.2 kW inverter prototypes, with six discrete SiC JFETs on one common heat sink and separated heat sinks, respectively, are built using the same circuit layout. Their EMI spectra are compared under unfiltered and filtered conditions. The experiments show that the separate heat sinks inverter system exhibits significantly reduced EMI. Last, three improved solutions are proposed, which effectively suppresses the emitted EMI to the target level.

Research on Commutating Over-Voltage Protection for ITER Poloidal Field Converter

This paper presents the commutating over-voltage snubber circuit design method of a thyristor converter that is applied to the International Thermonuclear Experimental Reactor poloidal field-converter module. In the course of poloidal field ac/dc converter normal operation, large transient surges called commutating over-voltages may be generated internally during the commutating process of thyristor, which poses a severe threat to system reliability and needs to be suppressed. In this paper, based on the analysis of reverse recovery transient of the parallel thyristors, the turn-off model of the PF converter thyristor is created and analytical expressions are derived, including the over-voltage crest value and the maximum over-voltage rise rate. Utilizing the analysis results, a systematic approach to the RC snubber circuit design is described.

RC Snubber Circuit of Large Gap Magnetic Driven System

Based on the single chip microcomputer (SCM) control theory, the control circuit of magnetic driving system of axial flow blood pump is designed. For the easy damage of TIP 122, which is used as the power switch of control circuit, RC snubber circuit is designed by analysis and experiments. And then an optimal matching of the key parameters is obtained to solve the security problem of the TIP 122. The experimental results show that the RC snubber circuit can improve the reliability and stability of the driving system, and to provide an experimental foundation for the further studies.

Solid-state fault isolation devices: application to future power electronics-based distribution systems

This study addresses the timely issues of modelling, and defining selection criteria for, a solid-state fault isolation device (FID) intended for use in power electronics-based distribution systems (PEDS). This work subsequently derives the FID parameters by mapping the characteristics of a conventional medium-voltage distribution system onto that of the PEDS envisioned under a new multi-university Engineering Research Centre. When conventional circuit breakers are used in distribution systems, they have a relatively long clearing time, causing the voltage to collapse for a significant time. A semiconductor circuit breaker, however, is expected to be able to switch fast enough to keep a voltage disturbance within acceptable limits. The main focus of this study is to address the operational issues of the interaction between the power electronic converters and the solid-state FID. The utilisation of rate of current decrease (di/dt) control during turn-off in conjunction with passive clamping devices to manage the overvoltage that results from very fast circuit breaker operation is introduced. In contrast to a simple conventional RC-snubber circuit, the proposed overvoltage management avoids high leakage current, which is the undesirable drawback of RC-snubber circuits. The presented prototype is experimentally verified with low and medium-voltage test circuits.

An Economical Auxiliary Commutated Thyristor Three-Phase Inverter Suitable for Pulse Frequency Modulation

A new economical auxiliary impulse commutated thyristor inverter is described that is capable of providing a wide range of output ac voltage and output frequency which is useful in variable speed ac drive applications. Output voltage control is provided by a pulse frequency modulation technique, and input dc voltage to the inverter is constant and can be provided by a diode rectifier bridge. The parameters for the various circuit elements, such as commutating inductances and capacitances, di/dt limiting series thyristor inductances, and dv/dt limiting RC snubber circuits are all calculated from a dynamic simulation of a single-phase version of the inverter circuit using a software named ATOSEC I developed at the Universitedu Quebec for a CDC 6400/IBM-370 computer. Experimental results obtained on a practical single-phase inverter are compared with those predicted from computer simulation and performance characteristics obtained in the case of a practical three-phase pulse frequency modulated inverter providing variable output voltage and variable output frequency are reported.