AC Chopper Circuit Research Articles

AC CHOPPER DESIGN AS UNIVERSAL MOTOR DRIVER BASED ON FUZZY LOGIC CONTROLLER

The electric motor has the function is converting electrical energy into mechanical energy. Based on supply, the electric motor is divided into two kinds of supply that are alternating current and direct current. The universal motor is an alternating current motor, the construction, and characteristics of a universal motor are the same as a direct current motor. Fuzzy Logic Controller is combined with AC Chopper circuit as a universal motor driver to control the motor universal speed at the stability of 1000 RPM and uses LM393 Optical Encoder sensor that will give a feedback signal to the fuzzy system as input. This research purpose is to implement AC Chopper as a universal motor driver to get more stable speed control combined with Fuzzy Logic Controller as feedback. In this study, the author uses the experimental method. With variable control are setpoint at 50% duty cycle and 1000 RPM speed reference of motor universal. Which is using 10 types of duty cycle values to get the average of driver efficiency and then using 2 kinds of load conditions for the controller test. The result of the driver test is to get speed control while without load condition has a period of 3 – 5 seconds to reach 1000 RPM. Then, when the load shedding condition has an overshoot value of up to 1193.33 RPM and reaches 1000 RPM in the range of 2 - 3 seconds. In this study, got the result of average driver efficiency is 85.41%.

SYNCHRONOUS AC CHOPPER FOR UNIVERSAL MOTOR SPEED CONTROL USING FUZZY LOGIC

The use of Universal type motors is very commonly used, both in daily life and in research activities. The universal motor can be used as prime mover generator PMSG (Permanent Magnet Synchronous Generator), which in its application there are obstacles, namely the difficulty of stabilizing the speed due to the influence of changes in the load connected to the PMSG, this affects the output voltage generated by the system. In this case, a speed stabilizer system is needed to stabilize the output voltage generated based on the load given to the system. AC Chopper is one of the circuits that can be applied in a speed control system that functions as an AC-AC voltage regulator which is the input of the Universal motor. Synchronous AC Chopper is one type of AC Chopper circuit which according to previous research has better performance in terms of efficiency than Basic AC Chopper. As for this control system, Fuzzy Mamdani logic is flexible and has a tolerance on existing data with control results having a settling time of ±15 seconds and an average efficiency of 84.99%.

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.

Direct AC-AC Step-Down Single-Phase Converter with Improved Performances

The paper presents two high-performance single-phase AC chopper circuits which perform AC-AC bidirectional direct conversion;one of them contains resistive loads and the other one is for inductive loads. It includes useful equations for chopper design. The correctfunctioning is tested by simulation.DOI: http://dx.doi.org/10.5755/j01.eee.18.10.1305

Interphase AC–AC Topology for Voltage Sag Supporter

A new topology is proposed in this paper to compensate voltage sags in power distribution systems. Voltage sag is one of the major power quality problems encountered by industries. The traditional voltage sag compensator, which is a dynamic voltage restorer based on energy storage device with a series-connected voltage-source inverter, is not adequate for compensating deep and long-duration voltage sags. As per the sensitive load concern, deep and long-duration sags are more vulnerable than shallow and short-duration sags. To compensate the voltage sag, a new interphase ac-ac topology is proposed that needs no storage device. The compensator of each phase is connected on the other two phases and the power is tapped from them. A single-phase compensator is realized with two ac chopper circuits and two transformers. By controlling the duty cycle of each ac chopper, the required voltage is realized to compensate the voltage sag. Analysis, simulation, and experimental results are presented to demonstrate the proposed concept.

Characteristic of an AC chopper circuit with LC filters in the input and output side

AbstractLC filters are connected to both the input and output side of the AC chopper circuit in order to remove the switching ripple and harmonics. Characteristics of THD and input power factor are examined by simulation and experiments. When the load is resistive, characteristics are minimally influenced by the filters. In the case of an inductive load, since two poles exist owing to the input and output filters, waveform distortion becomes large. This paper shows that THD can be improved by reducing input filter capacitance. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(2): 45–52, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20304

交流チョッパを結合した3レグ単相PWM電流形コンバータ

A single-phase PWM current source converter with three legs is proposed in this paper. The converter consists of main bridge circuit and ac chopper circuit, and a leg is commonly used for both circuits that are connected in parallel. The ac chopper with the PWM operation outputs the double-frequency ac voltage in the dc side, which cancels the dc pulsation of the main bridge. The pulsation-free dc voltage of the converter leads to the smooth dc current and the sinusoidal utility current. This allows the dc inductor to be greatly reduced. The experiments prove that the converter has good waveforms in small dc inductance. Moreover, the harmonic components of the currents are derived from the PWM switching pattern and are compared with measured ones. Theoretical results can be utilized for the determination of the circuit parameters in values.

Characteristic of an AC Chopper Circuit with LC Filters in the Input and Output Side

LC filters are connected both input and output side of the AC chopper circuit in order to remove the switching ripple and harmonics. Characteristics of THD and input-power-factor are examined by simulation and experiments. When the load is resistive, characteristics are little influenced by the filters. In case of the inductive load, since two poles exist owing to the input and output filters, waveform distortion becomes large. It is shown that THD can be improved by reducing input filter capacitance.

PWM Controlled ac Power Supply based on ac Chopper Technology and Its Applications

Many studies of the ac power supply have been reported. There are ac chopper circuits in these reports. The ac chopper circuits are effective method for ac power control. But, the ac chopper does not apply to practical use because it has some problems that needs bi-directional switch and ac snubber.In this paper, I propose the novel PWM controlled ac power supply based on ac chopper technology. Proposed PWM controlled ac power supply can solve problems of devices and snubber circuits because this circuit uses bilateral switch circuit instead of bi-directional switch. This paper describes circuit configuration and operation of PWM controlled ac power supply, and explains ac voltage regulator and series voltage compensator for application example through experimental results.

Time Ratio Controlled Three-phase AC Chopper

A general switching method suitable to control three-phase AC chopper circuit is presented. Such a method can be used with different circuit configurations of the AC chopper. Detailed harmonic analysis of the AC chopper when controlled by the time ratio control (TRC) strategy is given. TRC has the advantages of linear control of the fundamental component of the output voltage and elimination of all harmonics of order less than the frequency ratio by two. Also, the control signal can be generated easily. Experimental results verifying the analysis are presented.

A single-phase PWM current source type converter coupled with an ac chopper

A current source type converter can easily generate a sinusoidal current on the ac side by employing a PWM strategy. In the converter system for a single-phase supply, however, the dc current pulsates because the dc output voltage of the converter contains an ac component with twice the ac supply frequency. The dc current pulsations cause the ac current waveform to be distorted. Although the use of a dc reactor with large inductance reduces the dc current pulsations, the size and the weight of converter equipment including a dc reactor is large. Two-phase rectification using two full-bridge converters and a converter system with an ac chopper circuit has been proposed for elimination of the dc pulsations. In these converters, the number of switching devices comprising the circuit will unavoidably increase. To solve this problem, we propose a novel single-phase current source type converter coupled with an ac chopper circuit and the PWM method. In this circuit, two switching devices in the main bridge are used to form an ac chopper bridge with two added devices and a capacitor. This paper gives the experimental and theoretical waveforms and the steady-state characteristics. The results prove that a smooth dc current and a sinusoidal ac current are obtained, and that a great reduction of the dc inductance can be achieved by using the proposed converter. © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 36–45, 1998

A Single-Phase PWM Current Source Type Converter Coupling with AC Chopper.

A current source type converter can easily generate a sinusoidal current in the ac side by employing a PWM strategy. In the converter system for a single-phase supply, however, the dc current is pulsated because the dc output voltage of the converter contains the ac component with twice the ac supply frequency. The dc current pulsation causes the ac current waveform to be distorted. Although the use of the dc reactor with large inductance allows the dc current pulsation to decrease, the size and the weight of the converter equipment including the dc reactor become larger. A two-phase rectification by using two full-bridge converters and a converter system with ac chopper circuit have been proposed for the purpose of elimination of the dc pulsation. In these converters, the number of the switching devices which consist of the circuit can not avoid increasing.To solve such a problem, this paper proposes a novel single-phase current source type converter coupling with ac chopper circuit and the PWM method. In this circuit, two switching devices in the main bridge are used to form the ac chopper bridge with two added devices and a capacitor. This paper gives the experimental and the theoretical waveforms and the steady-state characteristics. The results prove that the smoothing dc current and the sinusoidal ac current are obtained, and the great reduction of the dc inductance can be achieved in the proposed converter.

Symmetrically Pulse Width Modulated AC Chopper

Output voltage, output current and line current waveforms in a symmetrically pulse width modulated (SPWM) ac chopper are analyzed for harmonic content, displacement factor, distortion factor, power factor and efficiency. The results are compared with those of phase controlled ac chopper circuit to assess the superiority of SPWM ac chopper. A novel SPWM ac chopper with minimum number of active components is presented. The circuit operation and the design considerations are discussed.