**5. Results and Discussion**

obtain the result [39,40].

#### *5.1. Simulation Results*

In the simulation studies, several experiments were carried out to confirm the effectiveness of the suggested VOC system. The DG capacities of the MG test system taken into consideration in this work are as follows. The SPV system has a 400 V output voltage rating with a 1 kW capacity. The load being considered is a three-phase, 1 hp squirrel cage IM connected at 415 V and 50 Hz.

The voltage control has been set up to satisfy each of the following requirements:


Each controller must successfully uphold the three requirements mentioned earlier and offer reliable control inside its application domain. The software platform MAT-LAB/Simulink has been used to implement the entire system. The SVM method is used to evaluate whether a PV system connected to a grid can improve power quality at the consumer terminals. Figure 7 depicts the creation of the SVM signal. The voltage waveforms and the current waveform share some phase and are both sinusoidal, as shown in Figure 8. Figure 9 illustrates how the speed of 1425 rpm was achieved while the load torque remained constant at 3.0 N-m, as shown in Figure 10. In accordance with carrier frequencies of 1 kHz and an MI of 0.9 (Figure 11), Figure 12 displays an FFT analysis of the current and voltage in the system under consideration. The THD<sup>i</sup> and THD<sup>v</sup> values were, respectively, 1.10% and 1.22%. Figure 13 depicts the voltage in the dc-link capacitor.

**5. Results and Discussion** 

IM connected at 415 V and 50 Hz.

(1) Decentralized control is achieved normally;

*5.1. Simulation Results* 

vides.

**Figure 8.** (**a**) Current and (**b**) Voltage waveform of the IM with the VOC-based SVM Controller. **Figure 8.** (**a**) Current and (**b**) Voltage waveform of the IM with the VOC-based SVM Controller. *Energies* **2022**, *15*, x FOR PEER REVIEW 12 of 22

In the simulation studies, several experiments were carried out to confirm the effectiveness of the suggested VOC system. The DG capacities of the MG test system taken into consideration in this work are as follows. The SPV system has a 400 V output voltage rating with a 1 kW capacity. The load being considered is a three-phase, 1 hp squirrel cage

The voltage control has been set up to satisfy each of the following requirements:

(3) All of the associated DGs follow the reference signal that the SVM algorithm pro-

Each controller must successfully uphold the three requirements mentioned earlier and offer reliable control inside its application domain. The software platform MATLAB/Simulink has been used to implement the entire system. The SVM method is used to evaluate whether a PV system connected to a grid can improve power quality at the consumer terminals. Figure 7 depicts the creation of the SVM signal. The voltage waveforms and the current waveform share some phase and are both sinusoidal, as shown in Figure 8. Figure 9 illustrates how the speed of 1425 rpm was achieved while the load torque remained constant at 3.0 N-m, as shown in Figure 10. In accordance with carrier frequencies of 1 kHz and an MI of 0.9 (Figure 11), Figure 12 displays an FFT analysis of the current and voltage in the system under consideration. The THDi and THDv values were, respectively, 1.10% and 1.22%. Figure 13 depicts the voltage in the dc-link capacitor.

(2) Under diverse system situations, the whole MG closed-loop model is stable;

**Figure 10.** Torque of the Induction Motor. **Figure 10.** Torque of the Induction Motor. **Figure 10.** Torque of the Induction Motor.

**Figure 11.** Modulation Index.

**Figure 11.** Modulation Index.

**Figure 12.** FFT analysis of the voltage and current of the Induction Motor.

**Figure 12.** FFT analysis of the voltage and current of the Induction Motor.

**Figure 9.** Speed of the Induction Motor when MI = 0.9.

**Figure 9.** Speed of the Induction Motor when MI = 0.9.

*Energies* **2022**, *15*, x FOR PEER REVIEW 12 of 22

**Figure 10.** Torque of the Induction Motor.

**Figure 10.** Torque of the Induction Motor.

**Figure 11.** Modulation Index. **Figure 11.** Modulation Index. **Figure 11.** Modulation Index.

**Figure 12.** FFT analysis of the voltage and current of the Induction Motor. **Figure 12.** FFT analysis of the voltage and current of the Induction Motor. **Figure 12.** FFT analysis of the voltage and current of the Induction Motor.

**Figure 13.** DC-Link voltage. **Figure 13.** DC-Link voltage.

#### *5.2. Experimental Verification of the Control Scheme 5.2. Experimental Verification of the Control Scheme*

The efficiency of the suggested VOC-SVM control-based PI controller, shown in Figure 3, has been tested using a suitable configuration. Its primary components are a Fluke power quality analyzer, three-phase inverter, dSPACE kit, power analyzer, and PV simulator. A PVS1010 PV emulator with dc programming is used to determine the panel properties. A real-time dSPACE DS1104 controller interface controls the system by conditioning each field signal. A dSPACE platform, shown in Figure 14, is used to integrate the Simulink model with the external hardware. A D/A converter is used to interface the inverter gating signals with dSPACE. A dSPACE DS1104 board is used to run Simulink, which has been used to implement the simulated design modelling. The suggested control's main benefit is the ability to precisely adjust the THD and dc-link voltage. The testing was carried out using the MATLAB/Simulink interfaced dSPACE platform to realize the adequate performance of a VOC-SVM control-based grid-connected PV system. The efficiency of the suggested VOC-SVM control-based PI controller, shown in Figure 3, has been tested using a suitable configuration. Its primary components are a Fluke power quality analyzer, three-phase inverter, dSPACE kit, power analyzer, and PV simulator. A PVS1010 PV emulator with dc programming is used to determine the panel properties. A real-time dSPACE DS1104 controller interface controls the system by conditioning each field signal. A dSPACE platform, shown in Figure 14, is used to integrate the Simulink model with the external hardware. A D/A converter is used to interface the inverter gating signals with dSPACE. A dSPACE DS1104 board is used to run Simulink, which has been used to implement the simulated design modelling. The suggested control's main benefit is the ability to precisely adjust the THD and dc-link voltage. The testing was carried out using the MATLAB/Simulink interfaced dSPACE platform to realize the adequate performance of a VOC-SVM control-based grid-connected PV system.

For this reason, it was assumed that the grid phase voltage was 415 V with a frequency of 50 Hz and dc-link voltages of 250 V. The practical response to a dc-link voltage For this reason, it was assumed that the grid phase voltage was 415 V with a frequency of 50 Hz and dc-link voltages of 250 V. The practical response to a dc-link voltage and SVM

and SVM switching pulse is illustrated in Figure 15. The test results clearly show that the

**Figure 14.** Experimental Setup of the three-phase inverter with VOC control using dSpace.

switching pulse is illustrated in Figure 15. The test results clearly show that the SVM-based VOC controller optimizes the dc-link voltage. and SVM switching pulse is illustrated in Figure 15. The test results clearly show that the SVM-based VOC controller optimizes the dc-link voltage.

*Energies* **2022**, *15*, x FOR PEER REVIEW 13 of 22

**Figure 13.** DC-Link voltage.

*5.2. Experimental Verification of the Control Scheme* 

The efficiency of the suggested VOC-SVM control-based PI controller, shown in Figure 3, has been tested using a suitable configuration. Its primary components are a Fluke power quality analyzer, three-phase inverter, dSPACE kit, power analyzer, and PV simulator. A PVS1010 PV emulator with dc programming is used to determine the panel properties. A real-time dSPACE DS1104 controller interface controls the system by conditioning each field signal. A dSPACE platform, shown in Figure 14, is used to integrate the Simulink model with the external hardware. A D/A converter is used to interface the inverter gating signals with dSPACE. A dSPACE DS1104 board is used to run Simulink, which has been used to implement the simulated design modelling. The suggested control's main benefit is the ability to precisely adjust the THD and dc-link voltage. The testing was carried out using the MATLAB/Simulink interfaced dSPACE platform to realize the adequate performance of a VOC-SVM control-based grid-connected PV system.

For this reason, it was assumed that the grid phase voltage was 415 V with a frequency of 50 Hz and dc-link voltages of 250 V. The practical response to a dc-link voltage

**Figure 14.** Experimental Setup of the three-phase inverter with VOC control using dSpace. **Figure 14.** Experimental Setup of the three-phase inverter with VOC control using dSpace.

**Figure 15.** SVM Switching Pulse and DC-Link Voltage. **Figure 15.** SVM Switching Pulse and DC-Link Voltage.

According to the IEEE 519 standard and Figure 14, an SVM based on ripple control was used to achieve reduced THD and described with the FFT spectrum of grid current under steady-state and dynamic operating circumstances. The waveforms were observed using a Fluke-43 spectrum analyzer with online numerical value illustration. The experimental voltage and current waveform of an inverter with a THDi and THDv for a modulation index of 0.3 are shown in Figure 16a–d. According to the IEEE 519 standard and Figure 14, an SVM based on ripple control was used to achieve reduced THD and described with the FFT spectrum of grid current under steady-state and dynamic operating circumstances. The waveforms were observed using a Fluke-43 spectrum analyzer with online numerical value illustration. The experimental voltage and current waveform of an inverter with a THD<sup>i</sup> and THD<sup>v</sup> for a modulation index of 0.3 are shown in Figure 16a–d.

Figure 17 depicts the voltage and current waveform with an FFT analysis with an MI of 0.6. Similarly, Figures 18 and 19 illustrate the voltage and current waveforms with FFT analysis for an MI of 0.9 using SPWM and SVM inverters. Figure 17 depicts the voltage and current waveform with an FFT analysis with an MI of 0.6. Similarly, Figures 18 and 19 illustrate the voltage and current waveforms with FFT analysis for an MI of 0.9 using SPWM and SVM inverters.

Figures 16–19 illustrate output current waveforms with various modulation indices for comparison. It can be seen that when the MI is fixed at 0.9, the output current waveform is more sinusoidal. THDi and THDv results for various modulation indices are similarly displayed. The optimum output signal is created by increasing the MI with the SVM technique, as can be seen in Figure 20. It is also evident that increasing the MI results in a decrease in current and voltage harmonics. Figure 21 shows the change in speed with MI. The comparative analysis of the hybrid system with THDs with different modulation indices is shown in Table 1. Figures 16–19 illustrate output current waveforms with various modulation indices for comparison. It can be seen that when the MI is fixed at 0.9, the output current waveform is more sinusoidal. THD<sup>i</sup> and THD<sup>v</sup> results for various modulation indices are similarly displayed. The optimum output signal is created by increasing the MI with the SVM technique, as can be seen in Figure 20. It is also evident that increasing the MI results in a decrease in current and voltage harmonics. Figure 21 shows the change in speed with MI. The comparative analysis of the hybrid system with THDs with different modulation indices is shown in Table 1.

(**a**) (**b**)

**Figure 15.** SVM Switching Pulse and DC-Link Voltage.

lation index of 0.3 are shown in Figure 16a–d.

dices is shown in Table 1.

analysis for an MI of 0.9 using SPWM and SVM inverters.

According to the IEEE 519 standard and Figure 14, an SVM based on ripple control was used to achieve reduced THD and described with the FFT spectrum of grid current under steady-state and dynamic operating circumstances. The waveforms were observed using a Fluke-43 spectrum analyzer with online numerical value illustration. The experimental voltage and current waveform of an inverter with a THDi and THDv for a modu-

Figure 17 depicts the voltage and current waveform with an FFT analysis with an MI of 0.6. Similarly, Figures 18 and 19 illustrate the voltage and current waveforms with FFT

Figures 16–19 illustrate output current waveforms with various modulation indices for comparison. It can be seen that when the MI is fixed at 0.9, the output current waveform is more sinusoidal. THDi and THDv results for various modulation indices are similarly displayed. The optimum output signal is created by increasing the MI with the SVM technique, as can be seen in Figure 20. It is also evident that increasing the MI results in a decrease in current and voltage harmonics. Figure 21 shows the change in speed with MI. The comparative analysis of the hybrid system with THDs with different modulation in-

**Figure 16.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter (**MI = 0.3**). **Figure 16.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter (**MI = 0.3**). **Figure 16.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter (**MI = 0.3**).

(**c**) (**d**)

(**MI = 0.6**).

(**MI = 0.6**).

(**c**) (**d**)

(**c**) (**d**)

**Figure 17.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter

**Figure 17.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter

**Figure 17.** *Cont.*

(**c**) (**d**)

(**MI = 0.3**).

**Figure 16.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter

**Figure 17.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter (**MI = 0.6**). **Figure 17.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SVM inverter (**MI = 0.6**). *Energies* **2022**, *15*, x FOR PEER REVIEW 16 of 22

**Figure 18.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SPWM inverter (**MI = 0.9**). **Figure 18.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SPWM inverter (**MI = 0.9**).

(**a**) (**b**)

(**a**) (**b**)

(**c**) (**d**)

(**MI = 0.9**).

**Figure 18.** (**a**) Voltage THD (**b**) Current THD (**c**) Voltage (**d**) Current of a three-phase SPWM inverter

**Figure 19.** (**a**) Voltage (**b**) Current (**c**) Voltage THD (**d**) Current THD (**e**) Voltage and (**f**) Current Phasor Diagrams of a three-phase SVM inverter (**MI = 0.9**). **Figure 19.** (**a**) Voltage (**b**) Current (**c**) Voltage THD (**d**) Current THD (**e**) Voltage and (**f**) Current Phasor Diagrams of a three-phase SVM inverter (**MI = 0.9**).

**Figure 20.** Comparison of Current THDs for the SPWM and SVM techniques.

**Figure 19.** (**a**) Voltage (**b**) Current (**c**) Voltage THD (**d**) Current THD (**e**) Voltage and (**f**) Current

**Figure 20. Figure 20.**  Comparison of Current THDs for the SPWM and SVM techniques. Comparison of Current THDs for the SPWM and SVM techniques.

(**c**) (**d**)

(**e**) (**f**)

Phasor Diagrams of a three-phase SVM inverter (**MI = 0.9**).

**Figure 21.** Change in speed vs. MI. **Figure 21.** Change in speed vs. MI.

**Table 1.** Comparative analysis of THD with different modulation indices. **Table 1.** Comparative analysis of THD with different modulation indices.


#### *5.3. Power-Loss Analysis 5.3. Power-Loss Analysis*

5.3.1. Conduction Losses

Power loss is the most crucial factor when calculating an inverter's efficiency. The most power is lost at the power switches. Knowing the power loss and heat dissipation, in addition to the inverter efficiency, is critical for constructing the proper heat sink. Total power losses in semiconductor power switches are often classified as static or dynamic. Power loss is the most crucial factor when calculating an inverter's efficiency. The most power is lost at the power switches. Knowing the power loss and heat dissipation, in addition to the inverter efficiency, is critical for constructing the proper heat sink. Total power losses in semiconductor power switches are often classified as static or dynamic.

The static loss includes conversion loss (on-state power losses) and cut-off loss. Failure to switch on and turn off makes up for the dynamic loss. The switching loss (*Psw*), conduction

switches. The blocking losses caused by leakage currents must be noted, though they are usually overlooked. However, switching losses are insignificant. The huge reduction in switching losses in VSI devices is the consequence of the on-and-off switch procedure during one fundamental period [41]. The switching device used in the VSI is Si-MOSFET.

The conduction power losses (*Pcond*) of MOSFETs may be calculated using a MOSFET

where *VDS*, *iD* = root mean square of the drain-to-source voltage and the drain current. *RDSon* can be determined by reference to the MOSFET datasheet because it depends on the gate-

to-source voltage, the junction temperature (*Tj*), and the drain current (*VGS*). Equation (42) provides the instantaneous MOSFET conduction power.

௦௦ = ௌ௪ + ௗ + (40)

ௌ()=ௌ(). (41)

approximation of the drain-to-source resistance (*RDSon*) [42].

The static loss includes conversion loss (on-state power losses) and cut-off loss. Failure to switch on and turn off makes up for the dynamic loss. The switching loss (*Psw*), conduction loss (*Pcond*), and blocking loss (*Pblocking*) are the three primary losses to calculate in power switches. The blocking losses caused by leakage currents must be noted, though they are usually overlooked. However, switching losses are insignificant. The huge reduction in switching losses in VSI devices is the consequence of the on-and-off switch procedure during one fundamental period [41]. The switching device used in the VSI is Si-MOSFET.

$$P\_{Loss} = P\_{Sw} + P\_{Conl} + P\_{blocking} \tag{40}$$

5.3.1. Conduction Losses

The conduction power losses (*Pcond*) of MOSFETs may be calculated using a MOSFET approximation of the drain-to-source resistance (*RDSon*) [42].

$$V\_{DS}(i\_D) = R\_{DSon}(i\_D).i\_D \tag{41}$$

where *VDS*, *i<sup>D</sup>* = root mean square of the drain-to-source voltage and the drain current. *RDSon* can be determined by reference to the MOSFET datasheet because it depends on the gate-to-source voltage, the junction temperature (*T<sup>j</sup>* ), and the drain current (*VGS*).

Equation (42) provides the instantaneous MOSFET conduction power.

$$P\_{\mathbb{C}, \text{MOSFET}}(t) = V\_{\text{DS}}(t)i\_{\text{D}}(t) = R\_{\text{DSon}}i\_{\text{D}}^2(t) \tag{42}$$

The following is an expression for the average conduction losses.

$$P\_{\text{C,MOSFET}} = \frac{1}{T\_{SW}} \int\_{0+\mathcal{Q}}^{T\_{on}} P\_{\text{C,MOSFET}}(t)dt\tag{43}$$

*Ton* = on-state period and ϕ = the phase angle.

$$R\_{\text{C,MOSFET}} = R\_{\text{DSoon}} i\_{\text{Drms}}^2 \tag{44}$$

It is also possible to determine a body diode's (*Pcond*,*diode*) conduction loss using its resistance dynamics (*Ron*,*diode*) and diode threshold voltage (*VT*), as demonstrated below:

$$P\_{\text{Con},diode} = V\_T I\_{\text{avg}} + R\_{on,diode} I\_{rms}^2 \tag{45}$$

#### 5.3.2. Switching Losses

Switching losses occur due to the slow transition from the on-state to the off-state and vice versa. Significant instantaneous power losses arise due to current flow and voltage via the switch becoming much more important than zero during the transition time [43].

During the turn-on interval, the energy dissipated.

$$E\_{SW,MOSFET(on)} = \left(V\_{dc}I\_{dc}\frac{t\_{c(on)}}{6}\right) - (V\_{dc} - V\_{on})I\_{dc}\frac{t\_{c(on)}}{3} \tag{46}$$

where *tc*(*on*) = the turn-on crossover interval and *ESw*(*on*) = energy dissipated during the turn-on interval.

When the MOSFET was turned off, the energy dissipated.

$$E\_{SW,MOSTET(off)} = \left(V\_{dc}I\_{dc}\frac{t\_{c(off)}}{6}\right) - V\_{on}I\_{dc}\frac{t\_{c(on)}}{3} \tag{47}$$

The total energy during turn-on and -off is:

$$E\_{SW,MOSFT} = E\_{SW,MOSFT(on)} + E\_{SW,MOSFT(off)}\tag{48}$$

**References** 

The switching losses had linear relations to the switching frequency and the switching current. The general average losses from swapping can be expressed as follows.

$$P\_{\rm SW,MOSFET} = \frac{1}{T\_{\rm SW}} \int\_{0+\mathcal{Q}}^{T\_{\rm off}} E\_{\rm SW,MOSFET} dt \tag{49}$$

Figure 22 shows the power-loss analysis of the MOSFET-fed three-phase inverter.

**Figure 22.** Power-Loss Analysis of Inverter. **Figure 22.** Power-Loss Analysis of Inverter.

#### **6. Conclusions 6. Conclusions**

In this study, SVM employing a PI controller was evaluated after considering the negative impacts of harmonics in a power system network. An SVM control technique was devised to reduce current harmonics and increase power quality. Pollution-free electricity generation via PV systems was prioritized along with improving power quality. This research paper focused on the harmonic analysis of a three-phase PWM inverter that supplies an IM using a variety of modulation indices. However, the work was limited, since losses were higher at high switching frequencies. The motor's speed can be controlled by creating suitable controls and switching methods. Since it can reduce switching losses and harmonic output signals, SVM is the ideal method for switching and regulating the inverter. In MATLAB, the three-phase PWM inverter that supplies the IM was modelled. An experimental setup was also created to validate the outcomes of the simulation. The results indicated that the IEEE Standard 519 limit of 5% for harmonic content in volt-In this study, SVM employing a PI controller was evaluated after considering the negative impacts of harmonics in a power system network. An SVM control technique was devised to reduce current harmonics and increase power quality. Pollution-free electricity generation via PV systems was prioritized along with improving power quality. This research paper focused on the harmonic analysis of a three-phase PWM inverter that supplies an IM using a variety of modulation indices. However, the work was limited, since losses were higher at high switching frequencies. The motor's speed can be controlled by creating suitable controls and switching methods. Since it can reduce switching losses and harmonic output signals, SVM is the ideal method for switching and regulating the inverter. In MATLAB, the three-phase PWM inverter that supplies the IM was modelled. An experimental setup was also created to validate the outcomes of the simulation. The results indicated that the IEEE Standard 519 limit of 5% for harmonic content in voltage and current was exceeded.

age and current was exceeded. Additionally, it was found that THD declined as the MI rose. Future research could use various PWM techniques to reduce harmonics while maintaining constant MIs. Finally, the system was evaluated using a real-time scaled-down prototype based on dSPACE, and the simulation results were confirmed. Each scenario's harmonic analysis was adequately adjusted to the IEEE-519 Standard's limitations. Additionally, it was found that THD declined as the MI rose. Future research could use various PWM techniques to reduce harmonics while maintaining constant MIs. Finally, the system was evaluated using a real-time scaled-down prototype based on dSPACE, and the simulation results were confirmed. Each scenario's harmonic analysis was adequately adjusted to the IEEE-519 Standard's limitations.

**Author Contributions:** Conceptualization. S.V., V.I., B.A. and M.B; Methodology. S.V., V.I and M.B.; Software. S.V., Formal Analysis. S.V., V.I., and B.A.; Investigation. S.V.; Resources. S.V., and M.B.; Data Curation. S.V., V.I., and M.B..; Writing–original draft preparation. S.V., V.I.; Writing—reviewing and editing. S.V., V.I., B.A.; Visualization. V.I.; Supervision. B.A., V.I. All authors provided critical feedback and collaborated in the paper. All authors have read and agreed to the published version of the manuscript. **Author Contributions:** Conceptualization. S.V., V.I., B.A. and M.B; Methodology. S.V., V.I. and M.B.; Software. S.V., Formal Analysis. S.V., V.I. and B.A.; Investigation. S.V.; Resources. S.V. and M.B.; Data Curation. S.V., V.I. and M.B.; Writing–original draft preparation. S.V. and V.I.; Writing—reviewing and editing. S.V., V.I. and B.A.; Visualization. V.I.; Supervision. B.A. and V.I. All authors provided critical feedback and collaborated in the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding. **Funding:** This research received no external funding.

**Informed Consent Statement:** Not Applicable.

**Institutional Review Board Statement:** Not Applicable. **Institutional Review Board Statement:** Not Applicable.

1. Lu, S.-M. A review of high-efficiency motors: Specification, policy, and technology. *Renew. Sustain. Energy Rev.* **2016**, *59*, 1–12.

**Informed Consent Statement:** Not Applicable.

**Data Availability Statement:** Not Applicable.

**Conflicts of Interest:** The authors declare no conflict of Interest.
