Soft Start Control Research Articles

Optimization and Improvement of Three-phase Asynchronous Motor Soft Starter Control Circuit

Abstract The soft starters of ABB company are used in a pumped storage power station. Sometimes, a phase absent fault was reported during the process of the motor starting and then led to starting failure. To solve this problem, this article first explained the working principle of the device, and then analyzed the design of the control circuit and the characteristics of the components. Combined with the actual inspection results to find the crux of the problem, It proposed optimization and improvement methods for the soft starter control circuit, and achieved the desired results.

Research on a soft-start method for LCC-LCC compensated bidirectional wireless power transfer system

The increased popularity of electric vehicles and the pursuit of user convenience makes bidirectional wireless power transfer (BWPT) an attractive technology for charging batteries. To improve the transmission efficiency of BWPT and limit the external radiated magnetic field, it is necessary to ensure the zero-voltage switching (ZVS) operation of the converter on the transmitter-side and limit the transient start-up current of the inverter when the system is working. To solve this problem, this paper proposes a soft-start modulation strategy based on an H-bridge inverter on the transmitter-side. First, the circular characteristics of dual LCC compensation topology are analysed based on an equivalent circuit. Secondly, according to the characteristics of the input impedance angle and current of the transmitter-side, a soft-start control method combining frequency and phase shift control is proposed. Finally, the feasibility of the proposed soft-start modulation strategy is verified on a prototype.

Maximum power point tracking control strategy based on frequency and amplitude control for the wave energy conversion system

This paper presents a pendulum-type wave energy conversion (WEC) system, which can change its natural frequency by a center of gravity adjustment mechanism. Based on this characteristic, a frequency and amplitude control (FAC) strategy is proposed to realize the maximum power point tracking (MPPT) of the WEC system. Firstly, the natural frequency of the WEC system is adjusted according to the peak frequency of the wave spectrum to make the device resonate with the waves, which is the frequency control (FC) method. The essence of the FC method is to change the position of the mass block inside the pendulum by controlling the angular displacement of the motor, so as to change the moment of inertia and recovery stiffness of the device. Secondly, the load of the mass block is very large, which brings a great challenge to the motor starting, so this paper proposes a soft-start control strategy to solve this problem. Thirdly, a weighted average method is proposed to calculate the intrinsic impedance of the WEC system under irregular waves, and then make the mechanical resistance of the power take-off (PTO) system equal to the intrinsic impedance of the WEC system by controlling the damping torque of the generator, which is the amplitude control (AC) method. By combining the FC method and AC method, the amplitude and phase conditions can be satisfied simultaneously to realize the MPPT of the WEC system. Finally, the feasibility and accuracy of the proposed control strategies are verified by simulation results.

The Phase Shifting Soft Startup of L-LLC Resonant Bidirectional DC-DC Converter Based on Current-Limiting Curve

The new L-LLC resonant bidirectional DC-DC converter (L-LLC-BDC) will produce a large resonance current and voltage inrush during the startup, posing a threat to the safe operation of the power device. Although a very high starting frequency can effectively suppress the inrush, it will also increase the output current demand of the driving ICs. This paper proposes a phase-shifting soft-start control strategy based on the current-limiting curve. Using operating mode analysis, the peak value of the resonant current is limited according to the output voltage and the phase shift angle of the switch, with the limit current curve at the startup stage drawn. By this current curve, a one-to-one correspondence between the output voltage and the phase shift angle of the switch is obtained. The phase-shifted soft-start control strategy can quickly establish the output voltage on the basis of a resonant frequency and can effectively suppress the resonance current inrush. An experimental prototype with a power of 6 kW and an input of 760 V and an output of 380 V is built. The experimental results prove the correctness and effectiveness of the soft start control strategy proposed in this paper.

Research on Intelligent Control System of High Power Soft Starter Based on Discrete Frequency Conversion Technology

Thyristor soft starter can effectively solve the three-phase asynchronous motor starting current problem, but its reduced starting current is achieved by reducing the output voltage and inevitably reducing the motor starting torque, it is difficult to use for heavy start of the occasion. A kind of soft starter based on discrete frequency conversion method is designed for the problem that the starting torque is small, the starting current is large, and the overloading cannot start. Based on the analysis of the working principle of the thyristor soft starter, this paper makes a deep research on the soft start control mode and realization method of the discrete frequency conversion without changing the main circuit structure of the original thyristor soft starter. Firstly, the soft starter hardware based on the three-phase anti-parallel thyristor main circuit and the current effective value is calculated by using high-speed A/D. Then, the soft start control strategy based on discrete frequency conversion is analyzed, with a 3kW/380V three-phase asynchronous motor for the test motor, respectively, the motor started a different way to simulate and test.

RETRACTED: Intelligent control for new topological structure of Z-Source inverter based on ARM

Due to the defects of Z-source inverter topology, an intelligent method to control topological structure of Z-source inverter based on ARM was put forward. Firstly, the double Z-source networks were connected in series, and then new topology structure of the series double Z-source inverter was designed. The steady-state working principle of the new topology structure was analyzed. Based on the steady-state working principle, ArmCortex-m3 processor and digital single-cycle control strategy were used to control the straight-through duty ratio, so that the soft start control and the intelligent control of Z-source inverter topology were realized. Simulation results show that the ratio between capacitor voltage and input voltage is low when the straight-through duty ratio is small. When the command value of DC-link voltage is 50 V, its command voltage value can be accurately tracked. Therefore, the proposed method has high control performance.

Inrush current reduction technology of DAB converter for low‐voltage battery systems and DC bus connections in DC microgrids

Low-voltage battery energy storage system and dual active bridge (DAB) converter control method for DC bus connection in DC microgrid. To use power efficiently in a DC microgrid, power must be easily transferred in both directions. DAB converters can easily transfer power in both directions using only the phase shift of the gate at 50% fixed duty on the primary and secondary sides. In the transient state, however, an overcurrent occurs to charge the output capacitor. A soft start algorithm is used to overcome this overcurrent problem. In the conventional method, the control complexity and response characteristics are slow because the duty control is included and the algorithm is performed in several stages. In this study, a gate drive circuit is constructed using a pulse transformer for 50% fixed duty control and short circuit protection. A soft start control algorithm is proposed, including a first-order phase shift scheme for the stable soft start at 50% fixed duty. The 3 kW prototype DAB converter is designed and implemented for bidirectional power conversion testing. The experimental results show that stable power transfer is achieved in the initial transient state through bidirectional output control and soft start.

Wide Input Voltage DC Electronic Load Architecture With SiC MOSFETs for High Efficiency Energy Recycling

A SiC three-stage converter architecture of energy recycling dc electronic load with high frequency isolation is proposed. With interleaving boost converters and a LLC-DCX using 1200-V SiC MOSFETs as high frequency isolation pre-regulation stage, the proposed architecture can adapt to wide input voltage of 150-750 V with high efficiency. As the bus voltage is 780 V, a T-type three-level inverter is accepted as grid-connected stage for low leakage current, small grid current harmonics and high conversion efficiency. The transfer mechanism of second harmonic component of the input current ripple is analyzed and is well suppressed by proposed current program control. An overshoot-free soft-start control is proposed to minimize resonant current peak using the inverter reverse operation. The switching frequency reduction modulation control is proposed to solve the extremely low duty-cycle problem under high input voltage and low load condition. A seamless mode transition digital control of three-stage load is proposed with smoothly switched capability between the input current loop and input voltage loop to solve the duty-cycle mutation problem during mode transition. A 5-kW, 300-kHz SiC prototype with 150-750 V input was built. The peak full-load efficiency of three-stage architecture is 95% at 750 V input. The power density is 12.6 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

A Triple-cycloconverter-based Soft-start Control Strategy Zh

Objective: The use of multiple-stage cycloconverters is suitable for variable-frequency speed control of high-voltage, large-capacity motors, for which it is sometimes necessary to establish separate controls for variable-frequency operation and the start-up phase. This approach effectively limits the starting current of the large-capacity motor by switching the phase relationship of the triple circuit’s output voltages to control the overall output voltage. Methods: We analyze a triple circuit using voltage vector analysis and simulation analysis with MATLAB modeling. Results: We find that our triple soft-start control strategy can be applied to large-capacity motors, as this strategy results in a pure sine wave output voltage and current, and maintains balance in the three-phase voltage during startup. Conclusion: In order to further decrease these types of effects, we will conduct more research on a cycloconverter that has six stages of the converter circuit, rather than the three stages mentioned before. Furthermore, the sextuple cycloconverter, which can be used to practically drive high capacity pumps or fans, will be developed by combining the “phase hopping” method and the soft-start method mentioned in this paper.

Adaptive soft starter for a three‐phase induction‐motor driving device using a multifunctional series compensator

This study proposes an adaptive soft starter control for induction motors using a multifunctional series compensator (MFSC). The proposed MFSC can operate in two modes: (i) the compensation mode for voltage sags and (ii) the virtual impedance mode for soft starting. Various MFSC functions are obtained by controlling the output characteristics of the series inverter. In the voltage sag compensation mode, a voltage is injected in series with the fault phase; as a result, the terminal voltage of the motor remains constant. In the soft-starter mode, the proposed converter injects adjustable virtual impedance in each phase; as a result, the starting current can be limited to the desired value. A novel control scheme and the optimal parameter selection of the MFSC are also presented. The design methodology of the proposed MFSC is verified using simulations conducted in MATLAB/Simulink software. Experimental results prove the capability and effectiveness of the proposed MFSC.

Cosine-Trapezoidal Soft-Starting Control Strategy for a Belt Conveyor

To improve the soft-starting performance of a belt conveyor, a cosine-trapezoidal soft-starting control strategy is proposed. With this strategy, the speed curve for soft-starting is S-shaped, continuous, and smooth. The acceleration and jerk are also continuous and smooth without discontinuities. The time-interval ratio of the horizontal and cosine curves can be changed via a single parameter setting, so that the strategy can be modified to meet different practical needs. In this paper, the soft-starting control strategy of cosine trapezoid is analyzed and simulated based on current international and domestic standards. The results show that compared with the classical soft-starting control strategy, the cosine-trapezoidal soft-starting control strategy enables the belt conveyor to start at its highest efficiency. Moreover, the energy savings are obvious, the safety performance is good, and the controllable performance is excellent.

Digital Soft Start Implementation for Minimizing Start Up Transients in High Power DAB-IBDC Converter

The dual active bridge isolated bidirectional DC-DC converter (DAB-IBDC) is one of the prime converters used in dual active bridge renewable energy storage system (RESS) applications, particularly where a high-power density is required. The digital DSP (Digital Signal Processer) control technique also provides intelligence to applications and achieves a super compact elegant system by reducing the complicated control hardware. All power converters, including the DAB-IBDC converter, often draw an inrush current, which is many times higher than their steady state current. The inrush current is the maximum current drawn by a converter for a very few milliseconds while being freshly energized. Although it appears for only a very few milliseconds, it can cause severe damage to the entire energy storage system, including the sources and loads. To save the RESS system from the starting inrush current and peak overshoot voltages, this paper proposes a five-phase digital soft-start control algorithm for a high-power DAB-IBDC converter that was implemented at a renewable energy storage system aimed at developing an intelligent self-powered energy zone. The proposed five phase digital soft-start algorithm can alone solve the startup transients without the use of any additional hardware. First, it prevents the output current and voltages from transients, such as the inrush current and peak overshoot voltages, by ensuring that the output current does not increase too rapidly while starting up. Second, it also eliminates the large backflow inrush current released by a partially discharged energy storage device at the starting period. Third, it helps achieve a simple super compact size DAB-IBDC converter with a simple elegant design by ensuring the control and soft-start in digital technology.

Research and Simulation of Electromagnetic Voltage-Regulated Soft Starter Based on Predictive Control

Aiming at the problems of large starting current and unsmooth starting of asynchronous motor, an electromagnetic voltage-regulated soft start control method based on predictive control is proposed. The model of motor soft starter based on predictive control algorithm is established. The control principle of predictive control algorithm is analyzed. The CARIMA model is used to adjust the parameters of motor starting process. With the help of MATLAB, the motor direct start model, the electromagnetic control soft starter model based on PID control algorithm and predictive control algorithm are simulated. The results show that the starting current waveform of the electromagnetic voltage regulator soft starter based on the predictive control algorithm is relatively flat, and the control algorithm can achieve a smooth start of the motor.

A Switched Inductor Quasi Z source-H-bridge Multilevel Inverter for Soft starting Control of Induction Motor using Direct Torque and Flux Control

An impedance source multilevel inverter schemes applied for traction and industrial drives application. Because it has unique merits ofharmonics less, transformer less drives control application and also soft start capability of induction drives. This paper proposed a reduced source z source Hbridge multilevel inverter and it is applied for induction motor drive control. In order to improving performance of induction motor performance, the torque and speed control is achieved using Direct Torque and Flux Control (DTFC)via phase voltage and current magnitude control. The proposed control scheme of Direct Torque and Flux Control (DTFC) is calculated through phase voltage and phase current sensing and then stator torque and flux is to be calculated byseparate estimation scheme. In reduced source Z source H-bridge multilevel inverter schemes, z source circuit gives a soft start capability across induction motor drive by controlling power magnitude across DC-Link. Reduced source is achieved using capacitor balancing circuit using a common DC-source. A single carrier and multi-reference of Phase Opposition and Disposition (POD) pulse width modulation topology is uses for proposed reduced source z source Multilevel Inverter for soft start control of induction motor.

Soft‐start control strategy for the three‐phase grid‐connected inverter with LCL filter

To solve the start-up inrush current existing in the three-phase grid-connected inverter, a soft-start control strategy for the three-phase grid-connected inverter with LCL filter is proposed. The analysis of start-up inrush current is illustrated in detail. The capacitor current of the LCL filter is used to detect the closure of the grid-connected switch, so the closing time of the grid-connected switch does not need to be known. The detailed procedure and flowchart of the proposed soft-start control method are provided. Finally, experimental results of a LCL-type three-phase grid-connected inverter verify the theoretical analysis. The control strategy is easy to implement. The start-up inrush current does not exist in the grid-connected inverter.

ARM Based Intelligent Soft Starter for Consumer Applications

The main objective of this project is to design a soft starter for consumer application, Gsm technology is used to get the voltage readings through mobile, The power theft also identified here by means of voltage measurement is presented in this paper. Here thyristor is used as soft switch. Three soft switches are used in three phases which is Star, Delta and Main phase. With the help of Gsm technology the motor is controlled through the mobile. The performance resulted from the past fault-tolerant soft starter control has demonstrated reduced motor starting transient torque pulsations as well as reduced motor inrush current magnitude. The present are soft starter for consumer application presented here to demonstrate the soundness and effectiveness of the soft starter for consumer approach and motor can be controlled from remote location.

The Evaluation of Teaching Quality Based on Fuzzy Method

For the problems that the street running state and information was difficult to feedback and reasonable control, we apply the topology model to the street lighting management system, and complete the optimization control in this paper. Using the fuzzy control theory to handle the road signals, the intelligent lighting region controller integrates the thyristor chopper with the autotransformer technology, carries out the soft start and slow slope control to the street light, and realizes automatic voltage and energy saving. At finally, the system can realize the energy-saving control and intelligent, networked management of city street lamp.

Study on Delay Synchronizing Rectification Control Method of Bi-Directional DC-DC Converter for Photovoltaic System

A novel photovoltaic (PV) system is proposed, which exhibits the advantages of better protection and more efficient control on charge/discharge of the battery. Furthermore, it can realize power management of the system. The key point of power management is how to control the bi-directional converter effectively. Considering traditional soft start strategy would be ineffective for bi-directional converter in the double sources application for the possibility of damaging the power device, a new soft start control method named delay synchronizing rectification control method is proposed. A 500W prototype converter is built to verify the theoretical analysis and the control method.

Novel Multilevel Hybrid Cascaded Inverter for High Power Motion Control Systems

The paper presents an analysis of a novel multilevel inverter that can be used in the power modules of motion control systems for soft starting and speed control of high power medium voltage synchronous and induction motors. The inverter is constructed from hybrid cascaded H-bridge cells. The advantages of the proposed inverter upon standard topologies are significant reduction of electrical components and as a result, smaller size and weight. The proposed approach can be extended to any desired number of voltage levels. Extensive simulation results validate the practicability of the proposed inverter. Several aspects, such as Total Harmonic Distortion Factor of the inverter output currents and voltages, harmonic content, and frequency spectrum distribution are studied.

An Energy-Saving Control System to Street Lamp Based on Sensor Networks

For the problems that the street running state and information was difficult to feedback and reasonable control, we apply the topology model to the street lighting management system, and complete the optimization control in this paper. Using the fuzzy control theory to handle the road signals, the intelligent lighting region controller integrates the thyristor chopper with the autotransformer technology, carries out the soft start and slow slope control to the street light, and realizes automatic voltage and energy saving. At finally, the system can realize the energy-saving control and intelligent, networked management of city street lamp.