Seven-Level Inverter with Reduced Switches for PV System Supporting Home-Grid and EV Charger

ABSTRACT:

This paper proposes a simple single-phase new pulse-width modulated seven-level inverter architecture for photovoltaic (PV) systems supporting home-grid with electric vehicle (EV) charging port. The proposed inverter includes a reduced number of power components and passive elements size, while showing less output-voltage total harmonic distortion (THD), and unity power factor operation. In addition, the proposed inverter requires simple control and switching strategies compared to recently published topologies. A comparative study was performed to compare the proposed inverter structure with the recent inverter topologies based on the number of components in the inverter circuit, number of components per output-voltage level, average number of active switches, THD, and operating efficiency as effective parameters for inverter performance evaluation. For design and validation purposes, numerical and analytical models for a grid-tied solar PV system driven by the proposed seven-level inverter were developed in MATLAB/Simulink environment. The inverter performance was evaluated considering grid-integration and stand-alone home with level-2 AC EV charger (3–6 kW). Compared with recently published topologies, the proposed inverter utilizes a reduced number of power components (7 switches) for seven-level terminal voltage synthesis. An experimental prototype for proposed inverter with the associated controller was built and tested for a stand-alone and grid-integrated system. Due to the lower number of ON-switches, the inverter operating efficiency was enhanced to 92.86% with load current THD of 3.43% that follows the IEEE standards for DER applications.

KEYWORDS:

1.      DC-AC converter

2.      Electric vehicles

3.      Home grid

4.      Maximum power point tracking (MPPT)

5.      Multilevel inverter

6.      Photovoltaic (PV) system

7.      Seven-level inverter

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:  

Figure 1. Circuit configuration of solar PV system in integrated with the grid and EV loads via the proposed 7level-inverter.

 EXPECTED SIMULATION SYSTEM:

(a) Solar irradiation

(b) PV current

(c) PV voltage

Figure 2. Cont

time(s)

(d)PV power

Figure 3. the pv panel current, voltage, and power.

 Figure 4. multi- Level inverter output voltage.

Figure 5. the injected current, voltage, and power variation. (a) Grid voltage and current; (b) Grid injected power.

 

Figure 6. The reference and actual injected currents of the seven-level inverter at irradiance variation.

 

Figure 7. Simulation results of the proposed 7-level inverter as level-2 EV charger (240 V, 3:6 kW); (a) loading profile, (b) multilevel output voltage, and (c) inverter voltage/pulsating current

Figure 8. Simulation results of the proposed 7-level inverter for house loads voltage control (2 kW). (a) Load reference and actual voltages, (b) Load voltage and current

CONCLUSION:

 This paper has presented a new topology of a single-phase seven-level inverter as an interface for grid-integrated and stand-alone solar PV systems. The circuit configuration This paper has presented a new topology of a single-phase seven-level inverter as an interface for grid-integrated and stand-alone solar PV systems. The circuit configuration This paper has presented a new topology of a single-phase seven-level inverter as an interface for grid-integrated and stand-alone solar PV systems. The circuit configuration and operation principle of the proposed inverter have been presented in detail a long with    the switching patterns and control strategy. A comparative study between the proposed inverter structure and the recent MLI topologies is enriched to reveal the features of the proposed inverter. The proposed MLI structure considers a reduced number of power switches, NC/L, and NAVG/Pole, which enhances the inverter operating efficiency and decreases its cost. Only seven switches have been utilized to synthesis voltage waveform of seven levels at the output terminals. The performance of the proposed inverter and associated control was investigated for grid-integrated and stand-alone PV systems based on simulation and experimental tests. The test platform includes a boost converter with MPPT control, which feeds the front-end of the proposed MLI. The results show that the proposed inverter exhibits an improved steady state response, and minimum settling time (i.e., 5 ms). THD of both voltage and current waveforms during grid-integration and stand-alone operations is 3.43%, which follows the IEEE-1547 harmonic standards for DER applications. In addition, the inverter offers a high operating efficiency of 92.86%, compared to most of the recently published topologies surveyed in this paper.

REFERENCES:

1. Solangi, K.; Islam, M.; Saidur, R.; Rahim, N.; Fayaz, H. A review on global solar energy policy. Renew. Sustain. Energy Rev. 2011, 15, 2149–2163. [CrossRef]

2. Ali, A.I.; Sayed, M.A.; Mohamed, E.E. Modified efficient perturb and observe maximum power point tracking technique for grid-tied PV system. Int. J. Electr. Power Energy Syst. 2018, 99, 192–202. [CrossRef]

3. Sayed, M.A.; Mohamed, E.; Ali, A. Maximum Power Point Tracking Technique for Grid tie PV System. In Proceedings of the 7th International Middle-East Power System Conference, (MEPCON’15), Mansoura University, Dakahlia Governorate, Egypt, 15–17 December 2015.

4. Ali, A.I.; Mohamed, E.E.; Sayed, M.A.; Saeed, M.S. Novel single-phase nine-level PWM inverter for grid connected solar PV farms. In Proceedings of the 2018 International Conference on Innovative Trends in Computer Eng. (ITCE), Aswan, Egypt, 19–21 February 2018; IEEE: Piscataway, NJ, USA, 2018; pp. 345–440.

5. Youssef, A.-R.; Ali, A.I.; Saeed, M.S.; Mohamed, E.E. Advanced multi-sector P&O maximum power point tracking technique for wind energy conversion system. Int. J. Electr. Power Energy Syst. 2019, 107, 89–97.

 

Improvement of PMSM Sensorless Control Based on Synergetic and Sliding Mode Controllers Using a Reinforcement Learning Deep Deterministic Policy Gradient Agent +

ABSTRACT:

The field‐oriented control (FOC) strategy of a permanent magnet synchronous motor (PMSM) in a simplified form is based on PI‐type controllers. In addition to their low complexity (an advantage for real‐time implementation), these controllers also provide limited performance due to the nonlinear character of the description equations of the PMSM model under the usual conditions of a relatively wide variation in the load torque and the high dynamics of the PMSM speed reference. Moreover, a number of significant improvements in the performance of PMSM control systems, also based on the FOC control strategy, are obtained if the controller of the speed control loop uses sliding mode control (SMC), and if the controllers for the inner control loops of id and iq currents are of the synergetic type. Furthermore, using such a control structure, very good performance of the PMSM control system is also obtained under conditions of parametric uncertainties and significant variations in the combined rotor‐load moment of inertia and the load resistance. To improve the performance of the PMSM control system without using controllers having a more complicated mathematical description, the advantages provided by reinforcement learning (RL) for process control can also be used. This technique does not require the exact knowledge of the mathematical model of the controlled system or the type of uncertainties. The improvement in the performance of the PMSM control system based on the FOC‐type strategy, both when using simple PI‐type controllers or in the case of complex SMC or synergetic‐type controllers, is achieved using the RL based on the Deep Deterministic Policy Gradient (DDPG). This improvement is obtained by using the correction signals provided by a trained reinforcement learning agent, which is added to the control signals ud, uq, and iqref. A speed observer is also implemented for estimating the PMSM rotor speed. The PMSM control structures are presented using the FOC‐type strategy, both in the case of simple PI‐type controllers and complex SMC or synergetic‐type controllers, and numerical simulations performed in the MATLAB/Simulink environment show the improvements in the performance of the PMSM control system, even under conditions of parametric uncertainties, by using the RL‐DDPG.

KEYWORDS:

1.      Permanent magnet synchronous motor

2.      Sliding mode control

3.      Synergetic control

4.      Reinforcement learning

5.      Deep neural networks

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Figure 1. Block diagram for FOC‐type control of the PMSM based on PI‐type controllers using RL.

EXPECTED SIMULATION RESULTS:

 

 

Figure 2. Time evolution for the numerical simulation of the PMSM control system based on the FOC‐type strategy.

Figure 3. Time evolution for the numerical simulation of the PMSM control system based on the RL‐TD3 agent for the correction of iqref.

Figure 4. Time evolution for the numerical simulation of the PMSM control system based on the

RL‐TD3 agent for the correction of udref and uqref.

Figure 5. Time evolution for the numerical simulation of the PMSM control system based on the

RL‐TD3 agent for the correction of udref, uqref, and iqref.

Figure 6. Time evolution for the numerical simulation of the PMSM control system based on control

using SMC and synergetic controllers.

Figure 7. Time evolution for the numerical simulation of the PMSM control system based on control

using SMC and synergetic controllers using an RL‐TD3 agent for the correction of iqref.

 

CONCLUSION:

This paper presents the FOC‐type control structure of a PMSM, which is improved in terms of performance by using a RL technique. Thus, the comparative results are presented for the case where the RL‐TD3 agent is properly trained and provides correction signals that are added to the control signals ud, uq, and iqref. The FOC‐type control structure for the PMSM control based on an SMC speed controller and synergetic current controller is also presented. To improve the performance of the PMSM control system without using controllers having a more complicated mathematical description, the advantages provided by the RL on process control can also be used. This improvement is obtained using the correction signals provided by a trained RL‐TD3 agent, which is added to the control signals ud, uq, and iqref. A speed observer is also implemented for estimating the PMSM rotor speed. The parametric robustness of the proposed PMSM control system is proved by very good control performances achieved even when the uniformly distributed noise is added to the load torque TL, and under high variations in the load torque TL and the moment of inertia J. Numerical simulations are used to prove the superiority of the control system that uses the RL‐TD3 agent.

REFERENCES:

1. Eriksson, S. Design of Permanent‐Magnet Linear Generators with Constant‐Torque‐Angle Control for Wave Power. Energies 2019, 12, 1312.

2. Ouyang, P.R.; Tang, J.; Pano, V. Position domain nonlinear PD control for contour tracking of robotic manipulator. Robot. Comput. Integr. Manuf. 2018, 51, 14–24.

3. Baek, S.W.; Lee, S.W. Design Optimization and Experimental Verification of Permanent Magnet Synchronous Motor Used in Electric Compressors in Electric Vehicles. Appl. Sci. 2020, 10, 3235.

4. Amin, F.; Sulaiman, E.B.; Utomo, W.M.; Soomro, H.A.; Jenal, M.; Kumar, R. Modelling and Simulation of Field Oriented Control based Permanent Magnet Synchronous Motor Drive System. Indones. J. Electr. Eng. Comput. Sci. 2017, 6, 387.

5. Mohd Zaihidee, F.; Mekhilef, S.; Mubin, M. Robust Speed Control of PMSM Using Sliding Mode Control (SMC)—A Review. Energies 2019, 12, 1669.

Improvement of PMSM Control Using Reinforcement Learning Deep Deterministic Policy Gradient Agent

ABSTRACT:

Based on the advantage of using the reinforcement learning on process control, provided by the fact that it is not necessary to know the exact mathematical model and the structure of its uncertainties, this article approaches the possibility of improving the performances of the Permanent Magnet Synchronous Motor (PMSM) control system based on the Field Oriented Control (FOC) type control strategy, by using the correction signals provided by a trained reinforcement learning agent, which will be added to the control signals ud, uq, and iqref . The type of reinforcement learning used is the Deep Deterministic Policy Gradient (DDPG). The combination possibilities of these control structures are presented, and their superiority over the FOC type control strategy is validated by numerical simulations.

KEYWORDS:

1.      Permanent magnet motors

2.      Field oriented control

3.      Reinforcement learning

4.      Intelligent agent

5.      Deep neural networks

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. Block diagram for FOC-type control of the PMSM based on reinforcement learning.

EXPECTED SIMULATION RESULTS:

Fig. 2. Time evolution for the numerical simulation of the PMSM control system based on the FOC-type strategy.

 

Fig. 3. Time evolution for the numerical simulation of the PMSM control system based on TD3 agent for the correction of udref and uqref .

 

Fig. 4. Time evolution for the numerical simulation of the PMSM control system based on TD3 agent for the correction of iqref.

 

Fig. 5. Time evolution for the numerical simulation of the PMSM control system based on TD3 agent for the correction of udref, uqref and iqref.

 

CONCLUSION:

This article presents the FOC-type control structure of a PMSM, which is improved in terms of performance by using a reinforcement learning technique. Thus, the comparative results are presented for the case where the reinforcement learning agent is properly trained and provides correction signals that will be added to the control signals ud, uq, and iqref. Numerical simulations are used to demonstrate the superiority of the control system that uses the reinforcement learning, and the following papers will study the possibilities for optimization in terms of the implementation of the reinforcement learning in the PMSM control.           

REFERENCES:

[1] B. Wu and M. Narimani, Control of Synchronous Motor Drives, in High-Power Converters and AC Drives , Wiley-IEEE Press, 2017, pp.353-391.

[2] B. K. Bose, Modern power electronics and AC drives, Prentice Hall, Knoxville, Tennessee, USA, 2002.

[3] H. Wang and J. Leng, “Summary on development of permanent magnet synchronous motor,” Chinese Control And Decision Conference (CCDC), Shenyang, China, 2018, pp. 689-693.

[4] Z. Liu, Y. Li, and Z. Zheng, “A review of drive techniques for multiphase machines,” in CES Transactions on Electrical Machines and Systems, vol. 2, pp. 243-251, June 2018.

[5] S. Sakunthala, R. Kiranmayi, and P. N. Mandadi, “A Review on Speed Control of Permanent Magnet Synchronous Motor Drive Using Different Control Techniques,”International Conference on Power, Energy, Control and Transmission Systems (ICPECTS), Chennai, China , 2018, pp. 97-102.

Research on Anti DC Bias and High Order Harmonics of Fifth Order Flux Observer for IPMSM Sensorless Drive

ABSTRACT:

Due to various nonideal factors, including the motor parameter mismatches, detection errors, converter nonlinearities, noise, etc. DC bias and high order harmonics exist in flux model, which make the traditional flux observer estimation inaccurate. In order to suppress DC bias and high order harmonics, an interior permanent magnet synchronous motors (IPMSM) sensorless drive method based on a fifth order flux observer (FOFO) is proposed in this paper. The proposed FOFO can completely remove DC bias and has strong filtering ability for high order harmonics. Additionally, the parameters of the FOFO are set through s-domain analysis. Then, the discrete FOFO is obtained to better implementation in digital systems. The proposed FOFO is verified by experiments on a 2.0-kW IPMSM drive platform.

KEYWORDS:

1.      Interior permanent magnet synchronous motors

2.       Fifth order flux observer

3.      Sensorless drive

4.      DC bias

5.      High order harmonics

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. The block diagram of IPMSM sensorless drive based on the FOFO.

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. Estimated rotor flux and position estimation error at 1000 r/min. (a) SOFO. (b) FOFO.

 

Fig. 3. Eestimated rotor flux and position estimation error at 1800 r/min. (a) SOFO. (b) FOFO.

 

Fig. 4. Estimated rotor flux and position estimation error at 50 r/min. (a) SOFO. (b) FOFO.

 

CONCLUSION:

In this paper, to further improve the performance of the flux observer to suppress DC bias and high order harmonics, a FOFO is proposed. Theoretical analysis shows that proposed FOFO has strong attenuation ability against the DC bias and harmonics, and motor parameters mismatch and additional interference can be avoided. Additionally, the parameters of FOFO are set through s-domain analysis. Moreover, for better implementation in digital systems, the structure of discrete FOFO is obtained. The effectiveness of the proposed FOFO has been verified at a 2.0-kW IPMSM sensorless drive. Compared with the SOFO sensorless drive, the proposed FOFO method has strong performance of suppressing stator voltage DC bias and stator current DC bias, and the proposed method has better suppression of stator resistance mismatch and q-axis inductance mismatch under the condition of stator current DC bias. The main advantages of the proposed FOFO are: 1) it is insensitive to DC bias; 2) it has strong suppression ability to high order harmonics; 3) it has high rotor position estimation accuracy. Our future research work will further study the application of FOFO in synchronous reluctance motors.

REFERENCES:

[1] S. Kim, J. Im, E. Song, and R. Kim, “A new rotor position estimation method of IPMSM using all-pass filter on high-frequency rotating voltage signal injection,” IEEE Trans. Ind. Electron., vol. 63, no. 10, pp. 6499-6509, Oct. 2016.

[2] H, Zhang, W. Liu, Z. Chen, S. Mao, T. Meng, J. Peng, and N. Jiao, “A time-delay compensation method for IPMSM hybrid sensorless drives in rail transit applications,” IEEE Trans. Ind. Electron., vol.66, no. 9, pp. 6715-6726, Sept. 2019.

[3] R. Antonello, L. Ortombina, F. Tinazzi, and M. Zigliotto, “Enhanced low-speed operations for sensorless anisotropic PM synchronous motor drives by a modified back-EKF observer,” IEEE Trans. Ind. Electron., vol. 65, no. 4, pp. 3069-3076, Apr. 2018.

[4] C. Li, G.Wang, G. Zhang, N. Zhao, and D. Xu, “Adaptive pseudorandom high-frequency square-wave voltage injection based sensorless control for SynRM drives,” IEEE Trans. Power Electron., vol. 36, no. 3, pp. 3200-3210, Mar. 2021.

[5] G. Zhang, G. Wang, H. Zhang, H. Wang, G. Bi, X. Zhang, and D. Xu, “Pseudo-random-frequency sinusoidal injection for position sensorless IPMSM drives considering sample and hold effect,” IEEE Trans. Power Electron., vol. 34, no. 10, pp. 9929-9941, Oct. 2019.

Reduced-Order Feedback Linearization for Independent Torque Control of a Dual Parallel-PMSM System

 ABSTRACT:

Connecting two PMSMs in parallel to a 2-level 3-leg inverter gives a way to build up a high power-density driving system using existing electronic devices. But this type of system has a nature of nonlinearity that creates an obstacle in high performance control and the original system cannot be feedback-linearized directly. This article presents a reduced-order feedback-linearization method. In the first place, an extra order-reducing step that separates the system as a main system and an auxiliary system is applied. Then a feedback-linearization method is applied to the reduced-order system. With these effort, the original system can be converted into a linear time-invariant system bringing the controller design problem into the linear domain. In the last step, a linear robust state-feedback controller is used to achieve the speed control as well as compensate the unmeasurable external load torque. An extensive experiment is given to verify the feasibility and good performance in a highly unbalanced load torque situation of the designed controller.

KEYWORDS:

1.      Parallel PMSM

2.       Robust control

3.       Feedback-linearization

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Proposed Controller Scheme.

EXPECTED SIMULATION RESULTS:

 

Figure 2. Speed And _D Response Of Speed Command Experiment.

 

Figure 3. Current Response Of Speed Command Experiment.

 

Figure 4. Speed And _D Response Of _D Command Experiment.

Figure 5. Current Response Of _D Command Experiment.

 CONCLUSION:

In this article, we have presented a two-step state-feedback controller for the MIDPMSM system such that the two machines are carried out in closed-loop systems for handling the highly unbalanced load torque situation. This article proposes a new way to linearize a nonlinear system if feedback-linearization cannot be applied directly. The major contribution can be summarized in three aspects. First of all, a state-space description for the MIDPMSM system is set up, and it is an affine nonlinear system with unknown inputs. And then, the original affine nonlinear system is linearized through two steps: order reducing and state-feedback linearization. With these two steps, the controller design problem is brought into the LTI system domain. Secondly, in the state-feedback linearization stage, the stability of the constrained two-dimensional subsystem (7) is fully considered and dealt with. Indeed, in order to keep its stability, the calculation of the disturbance compensation gain k is given by analyzing eigenvalue constraints through solving its characteristic polynomial. Thirdly, based on the reduced-order linearized system, a state feedback controller together with an integrator is designed. In this way, both goals, closed-loop stability and reference tracking, are reached. The experiment also proves that an open-loop machine can have the risk of becoming unstable when the "master-slave" method is used. The proposed controller can avoid this situation by putting both machines under closed-loop control. Although the proposed controller design method has shown its great advantages, at least one drawback of the controller is also left. This controller can hardly handle the singularity point of the system, which creates an obstacle. How to overcome the drawback becomes one of our next considerations.

 REFERENCES:

 [1] Z. Deng and X. Nian, ``Robust control of two parallel-connected permanent magnet synchronous motors fed by a single inverter,'' IET Power Electron., vol. 9, no. 15, pp. 2833_2845, Dec. 2016.

[2] J. M. Lazi, Z. Ibrahim, M. H. N. Talib, and R. Mustafa, ``Dual motor drives for PMSM using average phase current technique,'' in Proc. IEEE Int. Conf. Power Energy, Kuala Lumpur, Malaysia, Nov. 2010, pp. 786_790.

[3] A. A. A. Samat, D. Ishak, P. Saedin, and S. Iqbal, ``Speed-sensorless control of parallel-connected PMSM fed by a single inverter using MRAS,'' in Proc. IEEE Int. Power Eng. Optim. Conf., Melaka, Malaysia, Jun. 2012, pp. 35_39.

[4] A. Del Pizzo, D. Iannuzzi, and I. Spina, ``High performance control technique for unbalanced operations of single-vsi dual-PM brushles motor drives,'' in Proc. IEEE Int. Symp. Ind. Electron., Bari, Italy, Jul. 2010, pp. 1302_1307.

[5] J. M. Lazi, Z. Ibrahim, M. Sulaiman, I. W. Jamaludin, and M. Y. Lada, ``Performance comparison of SVPWM and hysteresis current control for dual motor drives,'' in Proc. IEEE Appl. Power Electron. Colloq. (IAPEC), Johor Bahru, Malaysia, Apr. 2011, pp. 75_80.