A Simple Two-Stage AC-AC Circuit Topology Employed as High-Frequency Controller for Domestic Induction Heating System

Ashraf, Naveed; Abbas, Ghulam; Ullah, Nasim; Alahmadi, Ahmad; Awan, Ahmed Bilal; Zubair, Muhammad; Farooq, Umar

doi:10.3390/app11188325

Cited by 6 publications

(2 citation statements)

References 20 publications

(36 reference statements)

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“…The created circuit capable of governing the output frequency and voltage is shown in Figure 2. This circuit is obtained by adding two more high switching transistors to the converter we developed in [22]. Six transistors and four diodes are used as switching devices along with one filtering inductor and two capacitors in its construction.…”

Section: Developed Circuit and Operationmentioning

confidence: 99%

“…Non-z-source power converting approaches are gaining more attention nowadays as they have no such issues [17][18][19]. These techniques are further classified as frequency regulation with and without voltage regulation features [20][21][22]. The frequency stabilization schemes stated in [19] have voltage regulation features, but their control strategies are non-identical to obtain the non-inverted and inverted forms of the input voltage at the output.…”

Section: Introductionmentioning

confidence: 99%

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A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output

et al. 2022

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Variable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into AC with an inverter circuit. The power quality concerns of both conversion stages are tackled by selecting high switching frequency PWM control and harmonics mitigation filters. Also, using a bulky DC-link capacitor is one of the big sources of low system reliability, so this approach increases the conversion losses, circuit, and control complications. The frequency step-down conversion is very attractive with direct AC-AC converters as it has a simple control and circuit structure, but these converters face poor power quality challenges once the output frequency is decreased with respect to an input. In these converters, the total harmonic distortion (THD) of the output voltage becomes very poor once the output frequency is reduced. The problem of high THD of the output is addressed in the power converting circuits implemented with line frequency multi-winding transformers. The required number of output winding and switching devices (diodes and thyristors) increases once the value of the output frequency is decreased. This will increase the overall volume, cost, and losses. The use of a bulky and costly line frequency transformer may be eliminated if AC voltage controllers have non-inverted and inverted voltage buck capabilities, such existing topologies either have complex control schemes or require a large number of operating devices. Therefore, in this research article, a new transformerless frequency step-down converter employing fewer devices is proposed. This approach is realized with a high-frequency controlled rectifier for the required voltage stabilization and a low-frequency inverter bridge for frequency control. Its validation is supported by the results attained from Simulink and practical-based prototypes.

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Section: Developed Circuit and Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output

et al. 2022

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A Bipolar Voltage Gain Boost AC-AC Converter Based on Four Switching Transistors

et al. 2021

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In numerous applications, such as the correction of grid voltage during voltage sag or swell events caused by system faults, it is necessary to ensure the stabilization of the output voltage with in-phase and out-phase features. This feature can also be employed in high-voltage-gain AC to DC conversion. AC voltage control schemes with one-stage conversion are viable approaches in this regard as only voltage regulation is needed. This conversion approach has strong potential for such applications as it is simple to realize. The voltage-correcting compensators are connected in series with the lines. The inputs of the AC voltage controllers employed in the voltage-correcting compensators may be connected to the faulty phase or other healthy phases. The number of AC voltage controllers used in a voltage compensator are one and two if its input power is drawn from the faulty and non-faulty phases, respectively. In the latter case, voltage gains and phase adjustment are major problems. There is no such issue in the first approach, where the voltage-correcting controller is connected to the line where the voltage variation is to be corrected. A high voltage gain more than the unity of both voltage polarities is required if the depth level of the correcting voltage is around 50% or more. The size and cost of a voltage-correcting controller depend on the number of switching transistors, as an isolated DC source with a gate-controlling circuit is a mandatory requirement for the switching operation of each transistor. Therefore, in the suggested research, an AC voltage controller having bipolar voltage gain is realized only with four switching transistors and six diodes, which reduces the overall size and cost significantly. The verification of the suggested topology is ensured by obtaining the simulation and real results from Simulink-based and practical-based platforms, respectively.

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Investigation of the Power Quality Concerns of Input Current in Single-Phase Frequency Step-Down Converter

et al. 2022

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Single-phase direct frequency converters are gaining attraction at the research and academic level as they are rapidly getting space over conventional multistage converters. The converters developed with a rectification and inversion process using a DC-link level are examples of multistage converters with some serious concerns such as an increase in the overall weight, losses, and cost. They also suffer from the low-reliability issue due to the issues involved with DC-link capacitors and problems linked with electromagnetic interference (EMI) caused by high-frequency pulse width modulation (PWM) switching. These problems are addressed with line frequency switching cycloconverters. In these converters, the power quality of the output voltage is improved by governing the amplitude of some selected output pulses or half-cycles. For this purpose, a low-frequency multiple tapping transformer may be used to obtain various voltage levels. However, its use is the main source of increased overall weight, losses, cost, and volume. In transformer eliminated topologies, high-frequency PWM control can be employed to control the magnitude of some selected half cycles of the output voltage. However, this approach may arise some problems related to EMI. In both control techniques, the attention is focused on the power quality of the output voltage only. The concern for the input current is ignored and not yet analyzed. This is one of the critical power quality concerns and requires further investigation. The magnitude control of the output half-cycles causes the variation in the amplitude of some half cycles of the input currents. As a result, all half cycles of the input current become non-symmetric. It generates harmonics that are always of low frequency and cannot be easily filtered out. It results in a high value of the harmonic factor (HF) of the input current. The improvement in the power quality of the output voltages severally degrades the power quality of the input currents. In this research, this problem is investigated with mathematically computed harmonic coefficients with a pulse selective approach. Also, a simple single-phase cycloconverter is introduced to improve the power quality index of the input current. The overall analysis is supported by the results obtained from a Simulink-based environment and a practically constructed prototype.

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A Simple Two-Stage AC-AC Circuit Topology Employed as High-Frequency Controller for Domestic Induction Heating System

Cited by 6 publications

References 20 publications

A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output

A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output

A Bipolar Voltage Gain Boost AC-AC Converter Based on Four Switching Transistors

Investigation of the Power Quality Concerns of Input Current in Single-Phase Frequency Step-Down Converter

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