Speed regulation of PV fed 8/6 switched reluctance motor using optimized controller

: Due to their low manufacturing costs and straightforward design, Switched Reluctance Motors (SRMs) and drives have recently seen an increase in demand. In addition to the SRM's double salient structure, the enhanced nonlinearity in the magnetization properties and torque output makes mathematical modeling of the SRM challenging. Therefore, new methods must be developed to increase steady state performance while also achieving greater speed control and precise dynamic reaction. This work presents an innovative, optimized controller for controlling the speed of PV-fed 8/6 SRM. The DC-DC Interleaved KY converter boosts the PV system's output, and the DC-link voltage is controlled by a PI controller. To transfer the enhanced DC to 8/6 SRM, a BR ((n+1) Diode and (n+1) Semiconductor) converter is employed. The speed of SRM is additionally managed using a Grey Wolf Optimized (GWO) PI controller. Using a multiport battery converter, the surplus power generated by the PV system is then stored in a battery. MATLAB/Simulink is used to complete the suggested tasks, and a prototype is run through simulation to measure performance.


Introduction
Switched Reluctance Motors (SRMs) have attracted a lot of research attention over the past years [1][2].The simple, rugged, and inexpensive structure perfectly describes the SRM.The rotor is neither wound nor is there a permanent magnet (PM).The SRM's cost is decreased by this structure, which also gives the motor the ability to operate at high speeds.
Due to the high-level centrifugal force, the SRM can operate at high speeds without mechanical issues.Additionally, the SRM drive's inverter features a dependable topology.Stator windings and upper and lower switches of the inverter are connected in series.By utilizing this architecture, the shoot-through issue that affects induction and permanent motor drive inverters can be eliminated [3][4].
Recently, Solar Photovoltaic (PV) technologies have become one of the most significant sources of new renewable energy.Based on the data on existing PV systems and anticipated future expansion, this relevance has emerged.Electrical network integration of PV systems presents numerous difficulties.These issues include reliability, stability, and nonlinearities in the power electronics (converters and inverters) and PV characteristics.Another problem is the variance in PV power generated as a result of environmental changes (temperature and irradiance).In addition to grid problems, other technological difficulties also surface under unusual operation conditions [6].
When a current flows through any one of the stages in an SRM, torque is created as the rotor lines up with the energized stator pole.Depending on how the rotor moves relative to the excited stage, the generating torque changes direction.It does not depend on the phase winding current flow.Each phase needs to be activated according to the position of the rotor in order to generate torque.The motor winding's excitation current is controlled by power electronic equipment [7][8].The effectiveness and estimation of the motor drive will differ depending on the type of converters being used.SR motors can run at higher speeds using the bridgeless resonance (asymmetric) power converter, which provides a faster rate of fall for phase current than other types of converters.Other converter topologies include Bridgeless Resonance (BR) converters, C-dump, C-dump with a freewheeling transistor.
The authors' classification of all SR motor problems and their suggestions for theoretical fixes were the basis for the analysis of the literature that followed in this study.This analysis was inspired by the papers [9-11], which they offered.The short circuit problems remedy only works when the motors are working under full charge and at a low speed.The authors recommended operating the motor with open diodes to fix the open circuit problem.Contrary to the common practice of disabling the impacted phase technique, the suggested alternatives were ineffective.
Using HMM-based statistical models, the authors of [12][13][14][15] examined the autonomous categorization of SR motor defects.By using the proposed methods, which are effective in all working modes, the modelling complexity of SR motors was reduced.In order to classify faults, the motor's loading was not constrained.The results of the experimental investigation demonstrate how effective the suggested approach is.Because there is a big training database, the classifier's reaction time is slow.
Permanent magnets are absent from the SRM, and its stator resembles that of a brushless DC motor.Besides, the double salient structure of SRM, also the mathematical modelling of SRM becomes complicated, due to the increased non-linearity, existing in the magnetization characteristics and the torque output.In order to manage the speed of the PV (Photovoltaic) fed 8/6 SRM, a novel optimized controller is provided in this work.The BR ((n+1) Diode and (n+1) Semiconductor) converter is used for transferring the improved DC to the 8/6 SRM.Furthermore, in order to regulate the speed of SRM, a Grey Wolf Optimized (GWO) PI controller is employed.Then, the excess energy generated from the PV system is stored in a Battery using a Multiport Battery converter.The following is the organizational structure of the paper: The suggested GWO-optimized PI controller is detailed in Section 2 of the system specifications; Section 3 describes the results with simulation outputs and with section 4, the study ends, by giving a conclusion.

System Description
Figures and tables, as originals of good quality and well contrasted, are to be in their final form, ready for reproduction, pasted in the appropriate place in the text.Try to ensure that the size of the text in your figures is approximately the same size as the main text (10 point).Try to ensure that lines are no thinner than 0.25 point.Recently, there is an increased demand for Switched Reluctance Motors (SRMs) and drives, due to their reduced manufacturing cost and simple structure.Permanent magnets are eliminated from the SRM, and its stator resembles that of a brushless DC motor.Besides, the double salient structure of SRM, also the mathematical modelling of SRM becomes complicated, due to the increased non-linearity, existing in the magnetization characteristics and the torque output.Thus, a novel optimized controller is presented for regulating the speed of PV (Photovoltaic) fed 8/6 SRM.
As part of the system under consideration, a PV system provides voltage to a connected SRM. Figure 1 shows a general representation of the system under investigation.DC-DC interleaved KY converters are used to boost the PV system's output at first, and PI/Cascaded ANN controllers are used to regulate the DC-link voltage.Furthermore, a PWM (Pulse Width Modulation) generator is used to deliver the obtained reference signal to the DC-DC converter.To transmit the enhanced DC to the 8/6 SRM, a BR ((n+1) Diode and (n+1) Semiconductor) converter is employed.The speed of SRM is additionally managed using a Grey Wolf Optimized (GWO) PI controller.Using a multiport battery converter, the surplus power generated by the PV system is then stored in a battery.In addition, a PI controller-based closed-loop approach is used to maintain stable DC output across the battery converter.The module output power can be determined simply from ...........( 7)

DC-DC Interleaved KY converter
The output from the PV system has been enhanced with the DC-DC interleaved KY converter.Due to their significantly lower size, losses, and cost when compared to other kinds of high step-up DC-DC converters, non-isolated converters have gained a lot of attention.Similar to buck converter behaviour, KY converters have a very quick transient load response.Additionally, these converters' output current doesn't pulsate.These converters' voltage gain can be improved, but it is currently low.
In this system, a DC-DC interleaved KY converter increases conversion voltage gain.The KY converter's voltage conversion ratio is higher than that of conventional DC-DC interleaved converters.Interleaved DC-DC converters are characterized by a high voltage conversion ratio, high conversion efficiency, low voltage stress on semiconductors, low input current ripple, and low conduction and switching losses.These steps are taken to determine this converter's voltage gain: ..........(8)

PI controller
For controlling the DC-link voltage, the PI controller has been utilized.Additionally, a PWM (Pulse Width Modulation) generator delivers the acquired reference signal to the DC-DC converter.With any changes in the operating conditions, the DC link voltage ( ) is changed rather than the voltage reference ( ).This modification will affect the inverter's power, current, and voltage.The PI controller for the DC link voltage is used to control unanticipated variations in the DC link voltage, like alterations in the environment, short circuit occurrences, voltage sags, or voltage swells.When compared to a conventional control strategy, this PI controller successfully makes sure that the DC link voltage returns to normal operation with less overshoot.If this DC link voltage is maintained effectively, the system's performance will improve.The reference power (P_ref), which is contrasted with the output PV power, is updated and stimulated by the recommended PI controller, which also controls the error signal between the DC link voltage and the intended reference.
Since that power was removed from the motor to maintain the variations in the DC connection voltage, these two powers are being compared.

Modelling of SRM
An 8/6 (8 stator poles, 6 rotor poles) pole SRM is constructed in a way that is twice as significant.Compared to other types of motors, the SRM's windings are simpler.They are only present on the stator poles and are simply coiled on those poles, with no winding on the rotor poles.When opposite poles are wound in series or parallel to produce a total number of phases equal to exactly half the number of stator poles, two stator poles are excited when a single phase is activated.Simple laminations serve as the salient poles' winding-free structure in the rotor.The benefit of SRMs is that they minimise copper losses during rotor winding.Silicon steel is preferred for its stampings, particularly in applications that require greater efficiency.Figure 2 depicts the construction of an 8/6 SRM.The static torque lookup table and 2 nd order interpolation technique can be used to compute the developed torque value between the present value and θ.The following mechanical equations can be used to determine the actual speed: .......... (11) where the difference between the rotor and reference speeds is the speed error.The following expression can be used to figure out the angular displacement θ of the rotor: The angle corresponding to the displacement of phase A in relation to another phase is given by: .......... (13) The equation below determines the positive period of phase: ......... (14) where, .............. (15) The length of negative current pulses depends on the amount of energy stored in the phase winding.The PI controller modifies the algorithm while it is executing.

BR converter
Each phase switch in SR motor drives with BR converters is connected in series to the phase windings.An SR motor's phases are independent of one another, therefore a winding failure in one phase has no bearing on the other phases.As a result, decreased output power ensures the motor will operate without interruption.The asymmetric bridge converter is the converter that is most frequently used in SR motors.The half-bridges of the asymmetric converter are each individually connected to the phases of the SR motor.During the hardchopping stage, the phases are powered on and off using the entire DC voltage.The winding phase of a switching pair receives power from the DC supply when it is turned on.Since the commutation current flows from the switch to the diode when both switches are off, the voltage across the phases has a negative potential.These asymmetric half-bridges enable soft switching in addition to zero-voltage freewheeling, allowing the creation of the phases from the positive potential and commutation at zero potential.

Grey wolf optimization
In order to regulate the speed of SRM, a Grey Wolf Optimized (GWO) PI controller is employed.In this method, the grey wolf optimization technique has been applied to improve the speed control parameters of the PI controller.The social structure and hunting habits of grey wolves are emulated in the new meta-heuristic optimization method known as "grey wolf optimization."This algorithm searches for prey and uses their hunting technique.In this algorithm, "four groups-Alpha (α), Beta (β), Delta (δ), and Omega (ω)"-are defined in a manner similar to the social structure of grey wolves (which live in groups).The wolf social structure is modelled throughout the design phase.The best The value of "a" is minimised from 2 to 0 to emphasize exploration and exploitation, accordingly.The positioning of the grey wolf is influenced by the location of its prey.The currently known three best solutions (α, β, δ) in this method are used to produce the desired result (prey).The following formulas are applied to modify their positions at the subsequent iteration.The position of the prey is the final position of Alpha as the wolves converge towards the prey.

Multiport battery converter
The excess energy generated from the PV system has been stored in the battery through a multiport battery converter, which is a bi-directional converter.Each port can be both an input and output port, and the multiport converter acts as the DC-DC converter.In such a way, the multiport converter transfer the received PWM signals to the BR converter.In addition, the excess energy generated from the PV system has been received from the interleaved KY converter shown in figure 1, then stores the energy in the battery for future use.Three bi-directional switches are connected in series and parallel to make up the multiport charger.The buck function is carried out via the series configuration of switches.The boost action is carried out by the parallel combination of switches.This multi-port charger charges when the solar panel is operational and also supplies output voltage when the solar panel is not available.We have an enabling option in this multiport charger that allows us to toggle the multi-port system on and off.The system will power the battery if the enable port is set to 1.The multi-port is unplugged from the battery if the enable port is set to 0. In addition, for retaining stable DC output across the battery converter, a PI controller-based closed loop technique is employed.

Result and Discussion
The PV-fed 8/6 switched reluctance motor using an optimized controller has been modelled.MATLAB/Simulink programming is utilized for simulation.Power electronic converters play a significant role between the source and the load as a result of advancements in the use of battery and solar energy.Initially, the KY converter receives the output from the solar panel as input.To maintain the necessary output voltage from the input, the two KY converters are interconnected.The interleaved KY converter is used to obtain both a high gain and a high output voltage.The output of the KY converter is fed into the SRM motor converter.The voltage waveform of a solar panel is depicted in figure 3.This is the PV panel voltage (92V) we feed into the KY converter from the PV panel.We receive a PV panel current of nearly 1.7 amps, which is depicted in figure 4 and also output current that receives 1.0 amps from the KY converter is depicted in figure 5.The output voltage (150V) from the KY converter is depicted in figure 6.For motor functioning, the SRM converter receives the 150V output from the KY converter.Using a PI controller, we may modify the output of the KY converter.We can attain the desired converter output by adjusting the reference voltage.

Fig. 7. Input voltage waveform
Before moving on to the SRM motor, the primary operation of the multi-port charger is described below.Figure 7 represents the PV panel voltage (92V) that is fed as an input to the multiport charger circuit.

Fig. 8. Output voltage waveform
Figure 8 represents the bidirectional multiport charger output (-700).The negative sign indicates that it is in the discharging condition.The multi-port charger is made up of three bi-directional switches that are connected in series and parallel.Switches configured in a sequence perform the buck function.Switches are used in parallel to perform the boost action.When the solar panel is active, this multi-port charger charges devices and also provides output electricity when a solar panel is not accessible.This multiport charger has an enabling option that we may use to turn the multi-port system on and off.If the enable port is set to 1, the system will supply power to the battery.If the enable port is set to 0, the multi-port is disconnected from the battery.There is a battery source like a multiport charger.A battery voltage current and soc waveform are present in the battery.11 represents the battery State of Charge (SoC) of the battery connected with the multi-port battery converter, which is nearly 92%.The SRM motor employed in this system is a four-phase, eight-pole machine, and to give it a pulse, we employed a vector control technique.In this vector control, the converter is given three inputs: a reference speed, a flux value, and the motor's actual speed.We are using a PI controller in this to estimate speed.The motor speed waveform, flux waveform, and current waveform are finally attained.

Conclusion
This paper proposes a unique, optimized grey wolf-optimized controller for the speed management of SRM (8/6 poles).Since the design problem for the suggested controllers is framed as an optimization process, GWO is utilized to find the best PI controller values.The interleaved KY converter for DC-DC.The extra power generated by the PV system is converted to battery storage using a Multiport Battery converter.The suggested work is executed in MATLAB/Simulink and a prototype is simulated to assess how well it performs.The proposed work provides high voltage gain, better DC-link voltage maintenance, efficient speed control and uninterruptible power supply to the SRM.

Figure
Figure11represents the battery State of Charge (SoC) of the battery connected with the multi-port battery converter, which is nearly 92%.The SRM motor employed in this system is a four-phase, eight-pole machine, and to give it a pulse, we employed a vector control technique.In this vector control, the converter is given three inputs: a reference speed, a flux value, and the motor's actual speed.We are using a PI controller in this to estimate speed.The motor speed waveform, flux waveform, and current waveform are finally attained.