Chopper Circuit Research Articles

Variable-Form Carrier-Based PWM for Boost-Voltage Motor Driver With a Charge-Pump Circuit

A boost-voltage motor driver with a charge pump (CP) circuit has higher efficiency than the conventional boost-voltage motor driver with a chopper circuit. This paper presents a variable-form carrier-based (VFCB) pulsewidth modulation (PWM) technique for the driver with the CP circuit. This technique has two triangular carriers and a variable-form carrier that is dependent on the voltage command signals. The technique is compared with the space vector modulation (SVM) technique in terms of the number of switching cycles, harmonics in the output voltage, linear modulation range, input power to the CP capacitor, processing time, and efficiency. The VFCB PWM technique is confirmed to operate the driver with the CP circuit at the same performance level as the SVM technique, with shortened processing time.

Device Performance and Switching Characteristics of 16 kV Ultrahigh-Voltage SiC Flip-Type n-Channel IE-IGBTs

Ultrahigh-voltage SiC flip-type n-channel implantation and epitaxial (IE)-IGBTs were developed, and the static and dynamic performance was investigated. A large device (8 mm × 8mm) with a blocking voltage greater than 16 kV was achieved, and an on-state current of 20 A was obtained at the low on-state voltage (Von) of 4.8 V. RonAdiff was 23 mΩ·cm2 at Von = 4.8 V. In order to evaluate the switching characteristics of the IE-IGBT, ultrahigh-voltage power modules were assembled. A chopper circuit configuration was used to evaluate the switching characteristics of the IE-IGBT. Smooth turn-off waveforms were successfully obtained at VCE = 6.5 kV and ICE = 60 A in the temperature range from room temperature to 250°C.

Electromagnetic interference caused by electric load of more electric aircraft

As an increasing number of power electronic converters are used in the electrical system of more electric aircraft( MEA),electro-magnetic interference( EMI) problems are becoming more and more severe both within the electrical systems and between different systems. Based on the electrical load characteristics of MEA,electrical load was classified into rectification,chopping and inverter. The conduction EMI current of the three major electrical load during the stable operation and the load surge of electrical loads were studied by modeling and simulations. EMI characteristics caused by the inverter load obtained was verified by experiments. The research results show that the conducted EMI to the power line is concentrated in the switch frequency of the power electronic device and the multiple frequency or so; the step change of the high power electrical load after the Buck chopper circuit makes the conduction EMI characteristics change significantly,which reflected in the frequencies of local maximum of amplitude spectrum. The study results provide the guidance for the EMI identification and the filter design of an independent electrical system.

A Modified Switching Control Strategy for Low-Voltage Faults in a Permanent-Magnet Synchronous Generator Wind Turbine System

Grid-connected wind turbines are developing rapidly nowadays, and thus their interactions with the power grid are becoming increasingly important. Grid-friendly wind turbines should possess stable output power, fast dynamic responses, and perfect fault-ride-through capability. This paper focuses on the low-voltage ride-through (LVRT) of a permanent-magnet synchronous generator (PMSG) wind turbine system equipped with fully rated neutral-point-clamped (NPC) converters. We propose a modified control strategy based on rotor-energy storage and the coordinated control of active and reactive power to meet grid interconnection standards. In addition, a dc chopper circuit works as a coordinated protection device for avoiding overspeed. The correctness and feasibility of the proposed control strategy are demonstrated through simulations. The large inertia link of the drive chain could be used to stabilize turbine operation under conditions of power dynamic mutation by taking advantage of its suitability for energy storage, which avoids the wind energy loss.

Real-Time Electrochemical Impedance Diagnosis for Fuel Cells Using a DC–DC Converter

A multiport bidirectional dc–dc converter with a diagnosis function for fuel cells that employs electrochemical impedance analysis was developed. The proposed converter, which is connected to electric double layer capacitors, can freely adjust the fuel cell voltage without fluctuation of the load voltage. A signal that consists of multiple frequency sinusoidal waves is superimposed as a duty ratio signal of the chopper circuit connected to the fuel cell, which enables simultaneous impedance measurement for these frequencies. The voltage and current values of the fuel cell are acquired by a digital signal processor to conduct fast Fourier transform calculations that give voltage and current spectra. The fraction of the spectra yields the electrochemical impedance. Experiments were conducted to validate the proposed method using a polymer electrolyte membrane fuel cell. The sinusoidal waves in the imposed signal have multiple frequencies to reduce the measuring time. The impedance characteristics determined using the proposed method are in good agreement with those obtained with an electrochemical instrument. To demonstrate the proposed method, the Nyquist plots when the fuel cell current, the operation temperature, and the stoichiometric ratios were changed and produced using the proposed method.

Sensing Power MOSFET Junction Temperature Using Circuit Output Current Ringing Decay

Junction temperature $(T_{j})$ sensing requirements for fast MOSFET junction temperature control and high-power fast switching power converter protection are not easily met with nonintrusive techniques. This paper presents a noninvasive circuit-model-based sensing method suitable for a high-bandwidth hard-switching converter power MOSFET junction temperature estimation without any additional temperature detector. For the purpose of demonstrating MOSFET junction temperature sensing, a chopper circuit is used. The ringing superimposed with a circuit load current is used for MOSFET junction temperature estimation. A “gate drive- $R_{\rm DS-on}{-}L{-}C$ ” resonant model is implemented, indicating the mechanism of power MOSFET turn-on dynamics. Modeling includes the gate-drive output parasitics, power MOSFET intrinsic parameters, PCB parasitics, and load parasitics. To evaluate the methodology, LTspice simulation and experimental results are studied.

Experimental Assessment with Wind Turbine Emulator of Variable-Speed Wind Power Generation System using Boost Chopper Circuit of Permanent Magnet Synchronous Generator

This paper presents experimental results and its assessment of a variable-speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG) and boost chopper circuit (BCC). Experimental results are obtained by a test bench with a wind turbine emulator (WTE). WTE reproduces the behaviors of a windmill by using servo motor drives. The mechanical torque references to drive the servo motor are calculated from the windmill wing profile, wind velocity, and windmill rotational speed. VSWPGS using PMSG and BCC has three speed control modes for the level of wind velocity to control the rotational speed of the wind turbine. The control mode for low wind velocity regulates an armature current of generator with BCC. The control mode for middle wind velocity regulates a DC link voltage with a vector-controlled inverter. The control mode for high wind velocity regulates a pitch angle of the wind turbine with a pitch angle control system. The hybrid of three control modes extends the variable-speed range. BCC simplifies the maintenance of VSWPGS while improving reliability. In addition, VSWPGS using PMSG and BCC saves cost compared with VSWPGS using a PWM converter.

Speed sensor‐less maximum power point tracking and constant output power operation of wind‐driven wound rotor induction generators

A simple control strategy has been proposed for maximum power point tracking (MPPT) mode and constant output power mode operation of variable speed wind turbine system employing wound rotor induction generators (WRIGs). The control strategy proposed in this paper has been implemented using TMS320LF2407A real time digital signal processor (DSP) and detailed procedure for such implementation is given. The salient feature of the proposed controller is that it employs only a single switch, which is an IGBT chopper and does not require any mechanical sensors or machine parameters. This makes the overall controller simple, flexible and robust. Further, space heating and battery loads are connected at rotor side of the machine through a diode bridge rectifier and the IGBT chopper. A method has been developed for the analysis of such grid connected WRIGs with variable external resistance at the chopper circuit. The successful working of the proposed controller has been amply demonstrated through extensive simulation and experimental results on the WRIG system for MPPT and constant output power operation.

Performance Comparison of Conventional Controller with Fuzzy Logic Controller using Chopper Circuit and Fuzzy Tuned PID Controller

It is often difficult to develop an accurate mathematical model of DC motor due to unknown load variation, unknown and unavoidable parameter variations or nonlinearities due to saturation temperature variations and system disturbances. Fuzzy logic application can handle such nonlinearities so that the controller design is fundamentally robust which is not possible in conventional controllers. The knowledge base of a fuzzy logic controller (FLC) encapsulates expert knowledge and consists of the Data base (membership functions) and Rule-Base of the controller. Optimization of both these knowledge base components is critical to the performance of the controller and has traditionally been achieved through a process of trial and error. Such an approach is convenient for FLCs having low numbers of input variables however for greater numbers of inputs, more formal methods of knowledge base optimization are required. In this work, we study the challenging task of controlling the speed of DC motor. The feasibility of such controller design is evaluated by simulation in the MATLAB/Simulink environment. In this study Conventional Proportional Integral Derivative controller, Fuzzy logic controller using a chopper circuit and Fuzzy tuned PID controller are analyzed and compared. Simulation software like MATLAB with Simulink has been used for modeling and simulation purpose. The performance comparison of conventional controller with Fuzzy logic controller using chopper circuit and Fuzzy tuned PID controller has been done in terms of several performance measures Such as Settling time, Rise time and Overshoot.

Performance Improvement of Hall Thrusters Using a Pulse-Synchronous Driver System

A new pulse-synchronous driver system is proposed for Hall thrusters. By applying a pulsating drive voltage with a frequency close to that of the discharge oscillation, the stable and synchronized operation of a Hall thruster can be realized. A pulsating boost chopper circuit is also proposed that is suitable for use as a pulse-synchronous drive and has many attractive features as the driver circuit for Hall thrusters. Moreover, it is demonstrated that the thrust performance is improved approximately 30% at 200 W input power by using the driver circuit. Pulse-synchronous driving is a new driving method optimized for thruster operation, and it is expected to become an essential technology for high-power Hall thrusters.

Maximum Power Control with a Boost Chopper and Grid Connection of PMSG Based Wind Turbine

The paper focuses mainly on the maximum control method of boost chopper circuit based PMSG wind turbine. It includes a full bridge rectifier, boost chopper circuit, and a two-level voltage converter. Therefore, this PMSG system can directly connect with the gird; and the active power and reactive power can directly control by the grid voltage oriented vector control. The maximum power control method of the boost chopper based PMSG was studied to charge a constant resistance. In this study, the maximum power control is improved to apply in gird connection system.

End user voltage regulation to ease urban low‐voltage distribution congestion

Owing to the increasing demand in the urban areas for new technologies such as heat pumps and electric vehicles (EVs), greater power capacity in low voltage (LV) distribution networks is becoming increasingly important. This study will investigate how to improve the power capacity through the implementation of point of use voltage regulation (PUVR). PUVR relies on a power electronics converter at each end-user. Most LV network cabling has a voltage limit of 1 kV, PUVR exploits this voltage rating to increase the network capacity. This study will describe and discuss the results from a viability study using data from a utility company, which shows that the capacity in the LV network could be increased by an additional 500 kVA. However, it was also found that PUVR using present off-the-shelf converters is not as cost-effective as replacing the LV network cables. Two power electronics topologies have been investigated in the simulation studies to date: the AC chopper circuit and the back-to-back inverter circuit. These two topologies were compared and the AC chopper was found to be a cheaper, more efficient topology. Therefore the AC chopper is more suitable for this application and may increase the viability of the PUVR.

Incremental Learning on a Budget and its Application to Quick Maximum Power Point Tracking of Photovoltaic Systems

Recent improvements in embedded systems has enabled learning algorithms to provide realistic solutions for system identification problems. Existing learning algorithms, however, continue to have limitations in learning on embedded systems, where physical memory space is constrained. To overcome this problem, we propose a Limited General Regression Neural Network (LGRNN), which is a variation of general regression neural network proposed by Specht or of simplified fuzzy inference systems. The LGRNN continues incremental learning even if the number of instances exceeds the maximum number of kernels in the LGRNN. We demonstrate LGRNN advantages by comparing it to other kernel-based perceptron learning methods. We also propose a light-weighted LGRNN algorithm, -LGRNNLight- for reducing computational complexity. As an example of its application, we present a Maximum Power Point Tracking (MPPT) microconverter for photovoltaic power generation systems. MPPT is essential for improving the efficiency of renewable energy systems. Although various techniques exist that can realize MPPT, few techniques are able to realize quick control using conventional circuit design. The LGRNN enables the MPPT converter to be constructed at low cost using the conventional combination of a chopper circuit and microcomputer control. The LGRNN learns the Maximum Power Point (MPP) found by Perturb and Observe (P&O), and immediately sets the converter reference voltage after a sudden irradiation change. By using this strategy, the MPPT quickly responds without a predetermination of parameters. The experimental results suggest that, after learning, the proposed converter controls a chopper circuit within 14 ms after a sudden irradiation change. This rapid response property is suitable for efficient power generation, even under shadow flicker conditions that often occur in solar panels located near large wind turbines.

Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

This paper presents a fast coordinated control scheme of the rotor side converter (RSC), the Direct Current (DC) chopper and the grid side converter (GSC) of doubly fed induction generator (DFIG) wind turbine generators (WTGs) to improve the low voltage ride through (LVRT) and high voltage ride through (HVRT) capability of the DFIG WTGs. The characteristics of DFIG WTGs under voltage sags and swells were studied focusing on the DFIG WTG stator flux and rotor voltages during the transient periods of grid voltage changes. The protection schemes of the rotor crowbar circuit and the DC chopper circuit were proposed considering the characteristics of the DFIG WTGs during voltage changes. The fast coordinated control of RSC and GSC were developed based on the characteristic analysis in order to realize efficient LVRT and HVRT of the DFIG WTGs. The proposed fast coordinated control schemes were verified by time domain simulations using Matlab-Simulink.

Dual Analysis of DC Chopper Circuit with LC Input Filter

The Buck circuit has been widely used in DC drive, charging and storage circuit, switching power supply and other power electronic devices. There exists very strong duality in the Buck circuit with input LC filter, especially in the structure of circuit, the equivalent circuits and the waveforms of input and output parts. On the basis of a theoretical model established in our work, an experiment is conducted to validate the equivalent circuits of both input and output parts, as well as the waveforms of associated capacitors and inductors. By choosing appropriate component parameters, the experimental results confirm the predictions of the theoretical model proposed.

Parallel switch‐based chopper circuit for DC capacitor voltage balancing in diode‐clamped multilevel inverter

In recent years, the multilevel inverters have become a practical solution for high-voltage application and power quality issues. In all multilevel topologies with several DC links, the voltage balancing of DC capacitors is known as a key problem. In this study, a novel topology of chopper circuit for DC capacitor voltage balancing in diode-clamped multilevel inverters (DCMLIs) is proposed. Presented topology has less number of switches with respect to other proposed topologies in literatures. Suggested topology is modular and has high reliability. Based on the presented control system for chopper switches, only one switch is turned on at each interval. Therefore the conduction and switching losses of the chopper circuit are reduced. Referring to the simulation results, fast dynamic response of suggested chopper and reduction in voltage stress on switches can be seen clearly. Computer-aided simulations are performed through MATLAB Simulink software. A prototype chopper circuit has been implemented and tested. The experimental results are also presented to verify the performance of the proposed chopper circuit and its control system for DC capacitors voltage balancing in DCMLIs.

A Compact Capacitor Charger using Single Chopper for Pulsed Power

In this paper, we miniaturize the capacitor charger for pulsed power applications. The capacitor charger circuit is constructed by a single chopper circuit using a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). A single chopper circuit has many advantages. However, due to operate by single switching device, operating power per switching device is higher than other topology. Then, a SiC (Silicon Carbide)-MOSFET is used for switching device, and compared to a single chopper circuit using a Si (Silicon)-MOSFET. In this research, we simulated a single chopper circuit concisely and developed the miniature capacitor charger for repetitive pulsed power generator. Charging time of Si-MOSFET charger and SiC-MOSFET charger are 310µs and 300µs respectively.

The Study of Optimal Structure and Value of Dump Resistance in Direct-Drive Permanent Magnet Synchronous Generators

This paper studied the direct-drive permanent magnet synchronous machine (permanent magnet synchronous generator, PMSG) Chopper optimal topology and resistance value. Compared the different Chopper circuit low voltage ride-through capability in the same grid fault conditions in simulation. This paper computes the dump resistance ceiling according to the power electronic devices and over-current capability. Obtaining the dump resistance low limit according to the temperature resistance allows, and calculating the optimal value by drop voltage in the DC-Bus during the fault. The feasibility of the proposed algorithm is verified by simulation results.

Laminated Bus Bar Design for Power Converter Circuit Considering Structural and Electrical Limitations

In order to improve the reliability of a power converter circuit, it is important to analyze the DC-side stray inductance between the DC capacitor and the power devices because this may affect the switching losses, lead to the occurrence of over-voltages in power devices, and increase the short-circuit current. As such, a number of studies have investigated these effects through calculations, experiments, and circuit simulations. However, thus far, no paper has discussed a design of the stray inductance. In this paper, the authors propose a design procedure for the stray inductance of the laminated bus bar for a high-speed switching circuit using SiC power devices. The relationship among the bus bar inductance, the over-voltage, and the short-circuit current is clarified using an analytical MOSFET model. In order to verify the analysis results, an experiment using SiC-MOSFET and SiC-SBD rated at 1,200V is conducted. From these results, the upper and lower limitations of the bus bar inductance for the buck chopper circuit are found, and the design procedure for the wiring structure considering the stray inductance is discussed using the inductance map.

高電力密度昇圧コンバータにおける最大許容電力と小型化性能

The DC-DC converter using integrated magnetic components that may achieve high power density has gained attention in environmentally-friendly cars such as electric vehicles (EV) and plug-in hybrid electric vehicle (PHEV). This paper focused on this circuit types using coupled indictors and close-coupled inductors that are the integrated magnetic components. In order to realize further high power density, calculation methods for the allowable power of the coupled indictors and close-coupled inductors are presented. The calculation method is based on detailed analysis of the characteristics of ripple current and magnetic flux. From the allowable power viewpoint, the volumes of the inductors are compared to a conventional interleaved boost chopper circuit in the same conditions. As a result, CCM operation is effective for downsizing of the magnetic components in case of the interleaved boost chopper circuit using coupled inductors. On the other hand, the interleaved boost converter using close-coupled inductors is effective for downsizing of the magnetic components with CRM operation.