Switching Surge Voltage Research Articles

Slew rate control of switching transient for SiC MOSFET in boost converter using digital active gate driver

This paper experimentally validates a fully digitalized active gate driver for suppressing the switching surge voltage of SiC MOSFETs in a boost converter. High-voltage power conversion systems are expected to adopt SiC unipolar power devices utilizing their high-speed switching capability. The high-speed switching operation causes the switching surge voltage in its switching transient. Active gate driving is a key technology for suppressing it. A fully digitalized active gate driver is particularly focused upon, which freely shaped the output gate-source voltage waveform by a multi-bit gate control signal. This driver achieves the dynamical control of the voltage/current behaviours of MOSFET in the switching transient by taking the Miller effect into account. It contributes to suppressing the switching surge voltage. This paper applies this digital active gate driver to a high voltage power conversion circuit. The switching surge voltage is experimentally suppressed by slew rate control with the digital active gate driver for various operating conditions. The results clarify the control strategy of the digital active gate driver for SiC MOSFET in a power conversion circuit.

Photo electric properties during streamer-to-leader transition in a long positive sphere–plane gap

In this work, a combined photoelectric detecting system is established using devices such as a photomultiplier, an electric field sensor based on optoelectronic integration, and a high-speed camera. The system is used to measure the instantaneous optical power, spatial electric field strength, and optical image during discharge of a 3-m-long sphere–plane gap under standard switching surge voltage of positive polarity. The test results show that the initial streamer of the 3-m-long sphere–plane gap can be divided into strong and weak ionization according to the rate of rise of optical power and electric field strength. Within the dark discharge period in the sphere–plane air gap, the intensity of the spatial electric field slightly jumps when the streamer-to-leader transition is completed, with an increase of about 162.59 kV/m. It is proposed to take the time when the intensity of the spatial electric field jumps in the dark discharge period as the criterion for the streamer-to-leader transition. The measured duration ta of the streamer-to-leader transition is calculated according to instantaneous optical power and spatial electric field strength. Based on the thermodynamic equilibrium equation, a Gallimberti simulation model for this streamer-to-leader transition is established. The duration ts for completing the streamer-to-leader transition is obtained according to the quantity Q of injected electric charges. By comparing the measured duration ta with the calculated duration ts of the streamer-to-leader transition, the rationality of the criterion is verified. The research results provide a basis for establishing an improved model for the inception of a leader in a long air gap.

Mechanism Clarification of Switching Loss and Surge Voltage / Current Reduction with Active Gate Drive for System Reliability Improvement

The active gate drive (AGD) technique is payed attention as a switching technique which can reduced both of switching loss and surge voltage. So far, only switching loss and surge voltage of main switch have been discussed, and the reverse recovery characteristic of rectification diode has not been discussed. In addition, the mechanism of loss and surge reduction has not been clarified. In this paper, the influence of AGD on reverse recovery characteristics, and the mechanism of loss and surge reduction are discussed for system reliability improvement. As a result, the mechanism of loss and surge reduction is clarified.

Development of High Temperature Operation SiC Power Module

We have developed a Silicon Carbide (SiC) power module that can operate at high temperatures up to 250 °C. Figure 1 shows the overview of the developed power module. The withstand voltage of the power module is 1200 V, two SiC - MOSFETs are built in, and it is a circuit composition of one phase of the power inverter. The two-layer SiC-Active Metal Brazed Copper(AMC) not only reduces the area of the power module but also reduces circuit inductance. In addition, this power module has a built-in snubber circuit that reduces the switching surge voltage of the SiC-MOSFET during high-speed switching. Generally, when the power module is operated at a high temperature, the reliability such as occurrence of lowering of the main bonding strength of the power module is significantly reduced due to thermal deformation. In this power module, the main components of the module are joined using eutectic solder with a solidus line above 350 °C. Copper-tungsten (CuW) was selected as the base plate material. Since the Coefficient of Thermal Expansion (CTE) values of CuW and SiN - AMC are close, it is possible to reduce the stress applied to these joints when the temperature changes. In addition, CuW has excellent thermal conductivity and heat capacity and suppresses heat generation of SiC-MOSFET. To evaluate the performance of this module, a switching test at 100 A was performed at 250 °C. The switching waveform is shown in Fig.2. The turn-off switching time tf was about 10 ns, and the switching surge voltage at that time was about 150 V. The turn-off switching waveform was almost the same from room temperature to 250 °C. As a result, it was shown that this power module can operate at 250 °C and the built-in snubber circuit works effectively at all temperatures. Acknowledgement This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation power electronics / Consistent R&D of next-generation SiC power electronics" (funding agency: NEDO). Figure 1

진공차단기 다중 재발호시의 서지 특성 해석

Vacuum circuit breakers are widely used as power switches for high voltage motors. This breaker generates a high switching surge voltage at the time of opening under lower power factor conditions such as start-up or no-load. When the breakdown voltage of the vacuum interrupter is lower than the transient recovery voltage, high frequency current flows and multiple reignition phenomena occur. Especially, the steep-fronted surge voltage which occurs in multiple re-ignition can act as electrical stress to the motor winding. Therefore, it is necessary to identify the causes and measures to reduce the electric stress.BR In this paper, we analyzed the effect of steep surge voltage and its reduction method when multiple reignition and high frequency quenching current occurred under the condition that the high voltage induction motor is shut off immediately.

Design and implementation of fast current releasing DC circuit breaker

Interruption of DC fault current in a DC system is more complex as compared to the AC one due to the high rate of rise of fault current and absence of natural zero crossing. Fast and hard switching action in DC current interruption causes excessive voltage across the circuit breaker. This paper investigates a new type of solid-state DC circuit breaker namely current releasing DC circuit breaker. The mechanism of current interruption in the current releasing DC circuit breaker is analyzed through an aggregated model. The design procedure is defined and simulation results are presented. In addition, a sensitivity analysis is carried out. Finally, the experimental results from a lab-scale prototype as a proof of concept are demonstrated. This study confirms that the current interruption time of the current releasing DC circuit breaker is remarkably less than the typical solid-state DC circuit breakers and it requires less number of semiconductors in its main breaking branch. Although the current releasing DC circuit breaker does not have any surge arrester in its structure, its switching surge voltage is significantly limited.

A Study on the New Active Clamp Snubber Applied Quasi Resonant Flyback Converter

In this paper, active clamp snubber method was proposed to reduce effectively the switching surge voltage of the conventional quasi resonant(QR) flyback converter. The usefulness and practicality of the proposed method in QR flyback converter were verified through steady state analysis and its experimental results. The performance of the proposed circuit was compared with the RCD snubber method. It was verified from the experimental results that the switch peak voltage of the proposed method was limited below 5% while the switch peak voltage of the RCD snubber was continuously increasing accordingly with the load current. Furthermore, this new active clamp snubber method could be applied to QR flyback and its power conversion efficiency was superior to the RCD snubber one.

Switching surge voltage suppression in SiC half-bridge module with double side conducting ceramic substrate and snubber capacitor

Switching surge voltage suppression in SiC half-bridge module with double side conducting ceramic substrate and snubber capacitor

Electrolytic Capacitor-Less Single-Power-Conversion On-Board Charger With High Efficiency

This paper presents an electrolytic capacitor-less single-power-conversion on-board charger with high efficiency. The proposed on-board charger is composed of a step-up ac–dc converter which includes an active-clamp circuit and a series-resonant circuit. The active-clamp circuit provides a zero-voltage switching of switches and recycles the energy stored in the leakage inductance of the transformer. Also, this circuit clamps the surge voltage of switches. The series-resonant circuit reduces reverse-recovery problem of output diodes by providing a zero-current switching. Especially, the control algorithm is developed to achieve high power factor under the universal input voltage without the help of the any auxiliary circuit. Thus, due to these characteristics, the proposed charger can achieve high power efficiency and high power factor. In addition, the structure of single-power-conversion is very beneficial to the on-board charger that is installed in the vehicle. To confirm the theoretical analysis and validity of the proposed on-board charger, a 2-kW prototype is implemented under the universal input voltage.

A Novel Control Algorithm for Conversion ofAC-DC with Improved Power Factor andEfficiency

A Single power-conversion ac–dc converter with high power factor and high efficiency. The proposed converter is derived by integrating a full-bridge diode rectifier and a series-resonant active-clamp dc–dc converter. To obtain a high power factor without a power factor correction circuit, this paper proposes a novel control algorithm. The proposed converter provides single power-conversion by using the novel control algorithm for both power factor correction and output control. Also, the active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. Moreover, it provides zero-voltage turn-on switching of the switches. Also, a series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the output diodes. The proposed converter provides maximum power factor 0.995 and maximum efficiency of 95.1% at the full load.

Single Power-Conversion AC--DC Converter With High Power Factor and High Efficiency

This paper proposes a single power-conversion ac-dc converter with high power factor and high efficiency. The proposed converter is derived by integrating a full-bridge diode rectifier and a series-resonant active-clamp dc-dc converter. To obtain a high power factor without a power factor correction circuit, this paper proposes a novel control algorithm. The proposed converter provides single power-conversion by using the novel control algorithm for both power factor correction and output control. Also, the active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. Moreover, it provides zero-voltage turn-on switching of the switches. Also, a series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the output diodes. The proposed converter provides maximum power factor 0.995 and maximum efficiency of 95.1% at the full load. The operation principle of the converter is analyzed and verified. Experimental results for a 400 W ac-dc converter at a constant switching frequency of 50 kHz are obtained to show the performance of the proposed converter.

고역률을 갖는 단일 전력변환 AC-DC 컨버터

This paper proposes a single power-conversion ac-dc converter with a dc-link capacitor-less and high power factor. The proposed converter is derived by integrating a full-bridge diode rectifier and a series-resonant active-clamp dc-dc converter. To obtain a high power factor without a power factor correction circuit, this paper proposes a suitable control algorithm for the proposed converter. The proposed converter provides single power-conversion by using the proposed control algorithm for both power factor correction and output control. Also, the active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. Moreover, it provides zero-voltage turn-on switching of the switches. Also, a series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the output diodes. The proposed converter provides maximum power factor of 0.995 and maximum efficiency of 95.1% at the full-load. The operation principle of the converter is analyzed and verified. Experimental results for a 400W ac-dc converter at a constant switching frequency of 50kHz are obtained to show the performance of the proposed converter.

지락고장에 의해 금속제 유연전선관에 유도된 개폐서지전압의 특성

This paper presents the transient behavior of the switching surge voltages generated by interruption of DC ground fault currents flowing through metal flexible conduits. All fault circuits consist of line parameters such as resistance, inductance, capacitance and conductance. The use of nonmagnetic metal conduits should be taken into account in order to reduce the inductance of battery charger distribution circuits. The frequency-dependent circuit parameters of metal flexible conduits were measured. The switching surge voltages generated at the ground fault circuit consisted of steel-galvanized alloy and aluminium conduits were investigated. As a result, the impedances of metal flexible conduits are significantly increased over the range of the frequency above 10 kHz and the switching surge voltages generated along aluminium flexible conduit are lower than those along steel-galvanized alloy conduit when DC fault current is interrupted.

Evaluation of Switching Surge Risks on the Low-Voltage Auxiliary System of Frequent Start-Stop Plant

In this paper, the switching surge risks on the low-voltage auxiliary system of the frequent start-stop plant are evaluated based on switching surge simulations, field measurements, and the investigation of a heavy damage case. First of all, modeling and switching surge voltage simulations by the Alternative Transient Program (ATP) of the Electromagnetic Transient Program for an actual plant are presented, where the switching surge voltages produced by the operation of load switches and source breakers of the low-voltage auxiliary system are simulated with respect to switch-close and switch-open operations with different switching modes, and different power-supply sources are considered. Then, the field measurement of switching surge voltages for a load circuit of an auxiliary system is implemented by the fast transient recorder; therefore, the ATP simulation correctness is verified. Finally, the affections of the switching surge voltages on insulation failure of equipment and the extended risks are evaluated by the comparisons between the results of simulation and measurement and the recommendations of the IEEE standard, and the investigation result of an actual heavy damage case. With the conduction of the evaluation, the enhanced measures for switching surge protection are proposed.

Converter-Switching Surges: Railroad Vehicle Power Converter Impact Studies

The application of new power electronics equipment to the rolling stocks of electrified railroad vehicles in recent years brought about the benefits of smooth acceleration and braking, higher efficient of propulsion systems, improved power quality, easy-and-simple maintenance of propulsion motor, and even lower procurement and service costs. Hence, they are generally regarded as a blessing and progress for the rail industry. The switching techniques and new power modules with fast response times are key components to make the above functions possible. If a railroad system is built with vehicles and traction power substations are designed for new equipment, then all power components should be designed to withstand the transient dynamic behavior, especially, the switching surge voltage and current. This is usually the responsibility of the general consultant or the turn-key contractor. Unfortunately, the situation in most electrified railroad systems is new, and renovated trains equipped with new converters and new IGBT power modules join service together with old trains and existing traction networks designed and commissioned decades ago. The impact of the switching surge voltage and current will become an issue of great concern, as illustrated by the two cases presented in this article. The problems presented in the two cases were eventually solved by some sort of soft-switching schemes as a remedy or correction solution. Yet, this problem should be addressed and examined in front of the commission phase to avoid impacts. In conclusion, clear specification of surge transients or permissible impacts need to be included in the procurement documents, and field tests are recommended to verify the compatibility of new power converters with the existing equipment in the entire system.

Experimental Investigation of High Step-Up DC-DC Converter for Fuel Cell System

This work aims to present experimental investigation of a high step-up DC-DC converter for fuel cell system. The proposed converter comprises of an input-current doubler, an output-voltage doubler, and an active-clamp circuit. The input-current doubler and the output-voltage doubler both provide much higher voltage conversion ratio by using a low turn ratio transformer. The low turn ratio increases the overall efficiency. A series resonant circuit of the output voltage doubler removes the reverse recovery problem of the rectifying diodes. The active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. Simulation has been carried out for the proposed converter with the help of OrCAD software. Experimental results show that the better performance of the converter is achieved at an input voltage of 30V.

Simulation analysis on high step-up DC-DC converter for fuel cell system

This paper presents a high step-up DC-DC converter for fuel cell system. The proposed converter comprises of an input-current doubler, an output-voltage doubler, and an active-clamp circuit. The input-current doubler and the output-voltage doubler both provide much higher voltage conversion ratio by using a low turn ratio transformer. The low turns ratio increases the overall efficiency. A series resonant circuit of the output voltage doubler removes the reverse recovery problem of the rectifying diodes. The active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. The proposed converter has been simulated in OrCAD software. Simulation results proved that based on the transformer design, better performance of the converter can be achieved for any value of input voltage. Key words: Series resonant circuit, active clamp circuit, input-current doubler, output-voltage doubler.

High Step-Up Active-Clamp Converter With Input-Current Doubler and Output-Voltage Doubler for Fuel Cell Power Systems

A high-efficiency high step-up DC-DC converter is proposed for fuel cell power systems. The proposed system consists of an input-current doubler, an output-voltage doubler, and an active-clamp circuit. The input-current doubler and the output-voltage doubler provide a much higher voltage conversion ratio without using a high turns ratio in the transformer and increase the overall efficiency. A series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the rectifying diodes. The active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. The operation principle of the converter is analyzed and verified. A 1 kW prototype is implemented to show the performance of the proposed converter. The prototype achieved a European efficiency of 96% at an input voltage of 30 V.

EMTP를 이용한 멀티레벨 인버터 구동 고압유도전동기에서 발생하는 과도과전압 저감필터의 효과분석

본 논문에서는 인버터 구동 고압유도전동기 운전시 스위칭 서지로 인하여 고압유도 전동기 단자에서 발생하는 과도과전압을 저감하기 위한 필터로 인버터 출력단자에서 dv/dt를 저감하는 LCR 필터와 전동기 입력단자에서 케이블과 유도전동기 특성임피던스를 매칭시키는 RC필터에 대한 과도과전압 저감특성을 분석하였다. 이 필터를 고압에 대용량 유도전동기에 적합하도록 EMTP(ElectroMagnetic Transients Program)를 이용하여 모델링 및 케이블 영향에 의한 필터의 과도과전압 저감효과를 전압파형과 고조파 스펙트럼으로 비교분석하고, 이를 토대로 고압 대용량 유도전동기에 사용될 필터를 제시하였다. 인버터 스위칭 서지에 의한 과도과전압은 유도전동기 고정자 권선에 심각한 전압 스트레스를 발생시켜 절연파괴를 일으키는 주요원인이 된다. 이러한 과도과전압을 저감위한 필터설계는 고압유도전동기 시스템에서 필수적인 요소임을 보였다. 또한 제시된 필터는 과도과전압을 효과적으로 저감시키는 것을 EMTP 시뮬레이션을 통하여 입증하였다.

A simplified method of calculating busbar inductance and its application for stray resonance analysis in an inverter dc link

Sinusoidal PWM control is widely applied to power electronic converters. The carrier frequency of recent converter products is gradually being raised in order to decrease current harmonics as much as possible. However, in the dc filter circuits of large capacity converters, the capacitance of a unit capacitor is relatively large, and the busbars are relatively long. Therefore, the resonant frequency is lower than those of small capacity converters. Consequently, there is a concern that the carrier frequency will become close to the resonant frequency, which will cause trouble. On the other hand, it is often necessary to decrease the inductance of the loop circuit consisting of a switching device and its by-pass circuit, in order to suppress the switching surge voltage. In both cases described above, it is important to be sure of the exact busbar inductance for reliable design. In this paper, a simplified method of calculating busbar inductance is proposed. This method is based on the partial inductance theory. In particular, the characteristics of a pair of busbars, and the use of the method are described. Finally, an application to stray resonance analysis in the dc filter circuit of a three level inverter is described in comparison with experimental data. From these results, we confirmed that the proposed method is usable to estimate busbar inductance quickly and accurately. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 49–63, 1999