Modified Phase-Shifted PWM Scheme for Improved Reliability in CHB MI

modified phase-shifted pwm scheme for reliability improvement in cascaded h-bridge multilevel inverters

ABSTRACT:

The cascaded H-bridge multilevel inverter (CHMI) is a modular structure that consists of many power semiconductor switches.With this increase in the number of power semiconductor switches, it is hard to predict and handle the failure of the devices, and hence reliability of CHMI decreases. The major cause of power semiconductor switch failure is junction temperature that is produced by power losses. The study proposes a multi-carrier pulse-width modulation (PWM) scheme for reduction in switching losses of CHMI.

PWM

One leg conducts switching operation with high frequency, while the other leg conducts switching operation with fundamental frequency. The switching operations with different frequencies cause unbalanced switching loss to each leg. Additionally, the switching frequency of the two legs is alternated to evenly distribute switching losses and junction temperature. Simulation and experimental results verify the performance of the proposed PWM scheme.

KEYWORDS:

  1. Cascaded H-bridge multilevel inverter
  2.  Phase-shifted pulse-width modulation scheme
  3. Reliability of power semiconductor switch
  4. Switching loss reduction

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Circuit Configuration of Three-Phase CHMI.

EXPECTED SIMULATION RESULTS:

Figure 2. Simulation of Conventional PS-PWM Scheme.

Figure 3. Simulation of Proposed PS-PWM Scheme In 5-Level CHMI.

Figure 4. Simulation of Proposed PS-PWM Scheme In 9-Level CHMI.

CONCLUSION:

This paper proposes a modulation method for a 5-level three phase CHMI to extend the life-time and improve reliability of power semiconductor switches. The proposed method is based on the PS-PWM scheme and decreased power losses via the clamped modulation period. The clamped signal reduces power loss, and other signal is reconfigured to maintain the quality of output waveforms such as the level of output voltage.

CHMI

Reduced power losses decrease the temperature of the power semiconductor switch, and thus the expected life-time of the power semiconductor switch is extended by using the proposed modulation method.

SWITCHING

The rotation method with 1/4 period is applied to proposed scheme for even switching loss and temperature among switches. The performance of the proposed method is verified via simulation and experimental results.

REFERENCES:

[1] B.Wu, High-Power Converter and AC Drives. Hoboken, NJ, USA:Wiley, 2006.

[2] D. Karwatzki and A. Mertens, “Generalized control approach for a class of modular multilevel converter topologies,” IEEE Trans. Power Electron., vol. 33, no. 4, pp. 2888_2900, Apr. 2018.

[3] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B.Wu, J. Rodriguez, M. A. Pérez, and J. I. Leon, “Recent advances and industrial applications of multilevel converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553_2580, Aug. 2010.

[4] J. Rodriguez, S. Bernet, B. Wu, J. O. Pontt, and S. Kouro, “Multilevel Voltage-Source-Converter topologies for industrial medium-voltage drives,” IEEE Trans. Ind. Electron., vol. 54, no. 6, pp. 2930_2945, Dec. 2007.

[5] G. P. Adam, I. A. Abdelsalam, K. H. Ahmed, and B.W.Williams, “Hybrid multilevel converter with cascaded H-bridge cells for HVDC applications: Operating principle and scalability,” IEEE Trans. Power Electron., vol. 30, no. 1, pp. 65_77, Jan. 2015.

The Study of Single-phase PWM Rectifier Based on PR Control Strategy

ABSTRACT:

Synchronous PI controller is usually used to track current in three-phase PWM rectifier with zero steady-state error which is difficult to achieve in the single-phase system. A novel proportional-resonant (PR) control scheme for single-phase PWM rectifier is proposed in the paper. Compared with traditional PI control and current hystereis control (CHC) methods

DC VOLTAGE

The PR control structure is simple and can reduce control time delay Significantly. The simulation results verify the feasibility of the proposed control scheme in the disturbance rejection. PWM Rectifier In addition, sinusoidal current zero static error control can be achieved without a coordinate transformation and the DC voltage can automatically adjust to changes of grid voltage, load value and frequency which contributes to energy conversion and bidirectional flow of electricity.

KEYWORDS:

  1. Single-phase rectifiers
  2. CHC control
  3. PR-based control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

(a) The topological structure

(b) The current control dynamic block diagram

Fig 1. The topological structure and the current control dynamic block diagram of PWM rectifiers.

EXPECTED SIMULATION RESULTS:

(a) The value of DC voltage.

(b) The value of AC current.

(c) Comparison between the feedback current and the referent current

Fig.2. The simulation waves based on CHC control scheme.

(a) The value of DC voltage.

(b) The value of grid voltage and AC current

(c) The value of actual voltage and predictive error.

(d) Comparison between the feedback current and the referent current

Fig 3.The simulation waves based on PR control scheme.

(a) Current Hystereis Control(CHC)

(b) Proportional-Resonant (PR) based control.

Fig 4. The AC current spectrum.

CONCLUSION:

From the above conducted studies, one can conclude that PR-based Control strategy for single-phase PWM rectifier presents better steady-state and can successfully achieve accurate regulation with fast dynamic response with minimum harmonic distortions. The simulation results show that sinusoidal current zero static error control can be achieved without a coordinate transformation and the DC voltage could automatically adjust to changes of grid voltage

AC

load value and frequency which contributes to energy conversion and bidirectional flow of electricity. The control algorithm is easy to be realized while the robustness and power quality is improved. The highlight of paper lies in applying PR regulator to the adjustment of sinusoidal AC current zero static error , building the system model of single-phase PWM rectifier in MATLAB/Simulink with CHC and PR control scheme respectively and giving proper comparisons to some degree.

REFERENCES:

[1] Song H.S, Nam K, Instantaneous Phase-angle Estimation Algorithm Under Unbalanced Voltage-sag Condition, IEEE Proc Generation, Transmission, and Distribution, Vol.147, No.6, 409-415, 2000.

[2] Zmood D.N, Holmes D.G, Stationary Frame Current Regulation of PWM Inverters with Zero Steady-state Error, IEEE Transactions on Power Electronics, Vol.18, No.3, 814-822, 2003.

[3] Yuan X, Merk W, Stemmler H, Stationary-frame Generalized Integrators for Current Control of Active Power Filters with Zero Steady-state Error for Current Harmonics of Concern Under Unbalance and Distorted Operating Conditions, IEEE Trans on Industry Applications, Vol.38, No.2, 523-532, 2002.

[4] ZHAO Qinglin, GUO Xiaoqiang, WU Weiyang, Research on Control Strategy for Single-phase Grid-connected Inverter, Proceedings of the CSEE, 60-64, 2007.

[5] JIANG Jun-feng, LIU Hui-jin, CHEN Yun-ping, A Novel Double Hystersis Current Control Method of Active Power Filter with Voltage Space Vector. Proceedings of the CSEE, Vol.24, No.10, 82-86, 2004.

Sensorless Start-Up Strategy for a 315 kW High-Speed Brushless DC Motor with Small Inductance and Non-ideal Back-EMF

ABSTRACT:

This paper presented a novel sensorless start-up strategy for a 315kW high-speed magnetic suspension brushless DC (BLDC) motor with small inductance and non-ideal back electromotive force (back-EMF). Two key strategies on the sensorless start-up strategy of BLDC motor were presented: (1) small current start-up strategy for the high-speed BLDC motor with small inductance, and (2) self-adaption control strategy to compensate the commutation error for the BLDC motor with non-ideal back-EMF in the start-up stage.

PWM

A hybrid pulse width modulation (PWM) strategy based on the load torque was proposed to limit the start-up current. An optimal motor start-up curve based on the system parameters was presented, and a self-adaption control strategy was proposed to solve the synchronous switching problem. The effectiveness and feasibility of the proposed method were verified by a series of experiments on the 315 kW-20000 rpm magnetic suspension blower platform.

KEYWORDS:

  1. BLDC motor
  2. Small inductance
  3. Non-ideal back-EMF
  4. Sensorless
  5. Start-up strategy
  6. Self-adaption control strategy

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. The block diagram of novel sensorless start-up strategy.

EXPECTED SIMULATION RESULTS:

Fig. 2. The comparisons experiment results of sensorless start-up strategy. (a) The start-up stage based on traditional sensorless “three-step” start-up method. (b) The start-up stage based on the sensorless start-up strategy proposed in this paper.

Fig. 3. The phase current and line-to-line voltages in the start-up stage without commutation compensation. (a) The synchronous error angle caused the waveform distortion in the start-up stage. (b) The synchronous error angle caused the motor out of step in the start-up stage.

Fig. 4. The comparisons experiment results of sensorless strategy under heavy load. (a) The start-up stage based on traditional sensorless “three step” start-up strategy. (b) The start-up stage based on the sensorless start-up strategy proposed in this paper

Fig.5. The curves of electromagnetic torque and the motor speed when the load torque changed in the start-up stage. (a) The curves under traditional sensorless start-up strategies. (b) The curves under sensorless start-up strategies proposed in this paper.

CONCLUSION:

This paper analyzed the main factors that influence the sensorless start-up performance of the high-power high-speed BLDC motor with small inductance and non-ideal back-EMF. A reliable start-up strategy was proposed by improving the detection of the initial rotor position, the closed-loop acceleration, and the synchronous switching process. The important conclusions were listed as follows.

(1) The rotor initial position can be positioned by the “two step” detection strategy. The start-up current can be adjusted according to the load torque in real time. Therefore, the method proposed in this paper ensured that the motor can start-up successfully under the load condition.

(2) The speed-up curve in the external-synchronization stage was optimized by analyzing the relationship between the motor speed and the terminal voltage. The rotor rotating time from the stationary position to a specify position was obtained by analyzing the average torque in 1/6 cycle and the rotor inherent characteristic.

(3) The synchronous switching process was improved by estimating the commutation error angle and the free decelerating. The influence of the back-EMF shape was analyzed by Eq. (28) and (29). The problems of high frequency noise and the rotor position error were solved by the free decelerating.

REFERENCES:

[1] A. Boglietti, C. Gerada, A. Cavagnino, “High-speed electrical machines and drives,” IEEE Trans. Ind. Electron., vol. 61, no. 6, pp. 2943-2945, Jun. 2014.

[2] W. Li, J. Fang, H. Li, J. Tang, “Position sensorless control without phase shifter for high–speed BLDC motors with low inductance and non-ideal back EMF,” IEEE Trans. Power Electron., vol. 31, no. 2, pp. 1354–1366, Feb. 2016.

[3] S. Chen, G. Liu, S. Zheng, “Sensorless control of BLDCM drive for a High-Speed maglev blower using a low pass filter,” IEEE Trans. Power Electron., vol. 32, no. 11, pp. 8845–8856, Nov. 2017.

[4] S. Shinnaka, “New “D-state-observer”-based vector control for sensorless drive of permanent-magnet synchronous motors,” IEEE Trans. Ind. Appl., vol. 41, no. 3, pp. 825–833, Jun. 2005.

[5] G. Liu, C. Cui, K. Wang, B. Han, S. Zheng, “Sensorless control for high–speed brushless DC motor based on the line–to–line back EMF,” IEEE Trans. Power Electron., vol. 31, no. 7, pp. 4669–4683, Jul. 2016.

Sensor-Less Five-Level Packed U-Cell (PUC5) Inverter Operating in Stand-Alone and Grid-Connected Modes

ABSTRACT:

In this paper a new mode of operation has been introduced for Packed U-Cell (PUC) inverter. A sensor-less voltage control based on redundant switching states is designed for the PUC5 inverter which is integrated into switching process. The sensor-less voltage control is in charge of fixing the DC capacitor voltage at half of the DC source value results in generating symmetric five-level voltage waveform at the output with low harmonic distortion. The sensor-less voltage regulator reduces the complexity of the control system which makes the proposed converter appealing for industrial applications.

GRID

An external current controller has been applied for grid-connected application of the introduced sensor-less PUC5 to inject active and reactive power from inverter to the grid with arbitrary power factor while the PUC auxiliary DC bus is regulated only by sensor-less controller combined with new switching pattern. Experimental results obtained in stand-alone and grid-connected operating modes of proposed PUC5 inverter prove the fast response and good dynamic performance of the designed sensorless voltage control in balancing the DC capacitor voltage at desired level.

KEYWORDS:

  1. Multilevel Inverter
  2. Packed U-Cell
  3. Sensor-Less Voltage Regulator
  4. PUC5
  5. 5-Level Inverter
  6. Power Quality

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1: PUC inverter topology

EXPECTED SIMULATION RESULTS:

Fig. 2: start-up capacitor charging, 5-level voltage generating and FFT Analysis

Fig 3: adding single-phase rectifier (as nonlinear load) paralleled with the RL load to the output of PUC5

Fig. 4: DC source voltage changes and capacitor voltage is tracking the reference value

Fig. 5: switches gate pulses

Fig. 6: grid-connected PUC5 with change in current reference amplitude

Fig. 7: THD, and Crest factor computation of injected grid current

Fig. 8: PUC5 inverter operation at different power factors a) PF = 0.86, _ = 30° b) PF = 0.86, _ = 60°

CONCLUSION:

The PUC5 inverter has been proposed in this paper while the capacitor voltage is balanced without involving any external controller and voltage feedback sensors. The proposed sensor-less voltage controller has been integrated into switching technique to work as open-loop system with reliable results. Moreover, another controller has been designed for the PUC5 inverter to work as unity power factor grid-connected inverter.

CURRENT

Low harmonics components in both voltage and current waveforms generated by PUC5, no need to bulky output filters, reliable and good dynamic performance in variable conditions (including change in DC source, load, power amount injected to the grid), requiring no voltage/current sensor in stand-alone mode

PUC5

low manufacturing costs and miniaturized package due to using less components and etc are interesting advantages of the introduced PUC5 topology which have been proved by experimental results in both stand-alone and grid-connected modes. The presented PUC5 inverter can be a challenging candidate for conventional photovoltaic application inverters.

REFERENCES:

[1] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[2] L. G. Franquelo, J. Rodriguez, J. I. Leon, S. Kouro, R. Portillo, and M. A. M. Prats, “The age of multilevel converters arrives,” IEEE Ind. Electron. Mag., vol. 2, no. 2, pp. 28-39, 2008.

[3] C. Cecati, F. Ciancetta, and P. Siano, “A multilevel inverter for photovoltaic systems with fuzzy logic control,” IEEE Trans. Ind. Electron., vol. 57, no. 12, pp. 4115-4125, 2010.

[4] M. Seyedmahmoudian, S. Mekhilef, R. Rahmani, R. Yusof, and E. T. Renani, “Analytical modeling of partially shaded photovoltaic systems,” Energies, vol. 6, no. 1, pp. 128-144, 2013.

[5] H. Mortazavi, H. Mehrjerdi, M. Saad, S. Lefebvre, D. Asber, and L. Lenoir, “A Monitoring Technique for Reversed Power Flow Detection With High PV Penetration Level,” IEEE Trans. Smart Grid, vol. 6, no. 5, pp. 2221-2232, 2015.

Sensorless BLDC Motor Commutation Point Detection and Phase Deviatio

ABSTRACT:

 Phase-to-neutral voltage or neutral-to-virtual neutral voltage zero-crossing points (ZCPs) detection method is usually used for sensorless BLDC motor commutation control. Unfortunately, neither of them can be realized in lower speed range.

DC

In this paper, a simple commutation point detection method is proposed based on detecting inactive phase terminal to dc-link midpoint voltage.

EMF

It eliminates the requirement of neutral wire or virtual neutral voltage and provides an amplified version of back electromotive force (EMF) at the ZCPs which makes the lower speed range detection possible. Sensorless BLDC Motor As the speed increasing, commutation point error is enlarged due to the low pass filter (LPF) et al. Utilizing the symmetry of the terminal to midpoint voltage the phase error can be corrected.

FNN

Sensorless BLDC Motor However, due to the nonlinear relationship between the detected voltage difference and phase error, it is difficult to regulate the error fast and robustly. Therefore, a novel phase regulator based on fuzzy neural network (FNN) is proposed

ZCP

in this paper with simple structure and learning ability. The validity of the proposed ZCPs detection method and commutation instant shift correction method are verified through experimental results.

KEYWORDS:

  1. Brushless dc (BLDC) motor
  2. Commutation signal
  3. Fuzzy neural network
  4. Sensorless motor
  5. Zero-crossing points (ZCPs) detection

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1Buck converter based BLDC motor drive system topology

EXPECTED SIMULATION RESULTS:

Fig. 2 Three kinds of ZCPs detection methods comparison.

Fig. 3 Convergence speed comparison between PI controller and FNN-based controller at 18000rpm.

Fig. 4 Performance comparisons between PI controller and FNN-based controller during 10000rpm~13000rpm.

Fig. 5 Performance comparisons between PI controller and FNN-based controller during 3000rpm~7000rpm.

Fig. 6 Performance comparisons between direct calculation method and FNN-based controller at 5000rpm.

Fig. 7 Speed range tests for the terminal to virtual neutral voltage-based method and the proposed method.

Fig. 8 Transient performances of the proposed method.

CONCLUSION:

Sensorless BLDC Motor In this paper, a novel commutation point detection method is proposed. It is realized based on detecting the ZCPs of inactive phase terminal to dc-link midpoint voltage. Since it provides an amplified version of back-EMF at the ZCPs

TERMINAL

this method makes the sensorless driving in lower speed range possible. Then, the relationship between the phase shift and the sampled terminal to midpoint voltage difference is derived, and its influencing factors are analyzed in detail.

FNN CONTROLLER

Sensorless BLDC Motor Based on this relationship, a robust and fast commutation point phase deviation correction method is proposed based on the FNN controller. The experiments show that the proposed controller is effective in both steady-speed control and variable-speed control.

PI CONTROLLER

It exhibits fast convergence behavior in the whole speed range compared with the PI controller, and it presents strong robustness compared with the direct calculation method even if motor parameters have large fluctuations.

REFERENCES:

[1] W. Jiang, H. Huang, J. Wang, et al, “Commutation Analysis of Brushless DC Motor and Reducing Commutation Torque Ripple in the Two-Phase Stationary Frame,” IEEE Trans. Power Electron., vol. 32, no. 6, pp. 4675–4682, Jun. 2017.

[2] W. Chen, Y. Liu, X. Li, et al, “A Novel Method of Reducing Commutation Torque Ripple for Brushless DC Motor Based on Cuk Converter,” IEEE Trans. Power Electron., vol. 32, no. 7, pp. 5497–5508, Jul. 2017.

[3] S.Zheng, B.Han, L.Guo. Composite Hierarchical Antidisturbance Control for Magnetic Bearing System Subject to Multiple External Disturbances [J]. IEEE Transactions on Industrial Electronics, 2014, 61(12): 7004-7012.

[4] S.Zheng, H.Li, B.Han, J.Yang. Power Consumption Reduction for Magnetic Bearing Systems during Torque Output of Control Moment Gyros [J]. IEEE Transactions on Power Electronics, 2017, 32(7): 5752-5759.

[5] T. Chun, Q. Tran, H. Lee, “Sensorless Control of BLDC Motor Drive for an Automotive Fuel Pump Using a Hysteresis Comparator,” IEEE Trans. Power Electron., vol. 29, no. 3, pp. 1382–1391, Mar. 2014.

Novel Single Stage Power Factor Corrected LED Driver Topology

ABSTRACT:

Single Stage Power Factor This paper proposes a novel converter topology based on a single stage LED driver with Power Factor Correction (PFC) which is optimized for weight, volume and cost, for space constrained environments such as Aerospace exterior lighting product. The proposed topology utilizes a single switch to harmonize the input current as well as control the intensity of lighting system.

PFP

Single Stage Power Factor A typical Power Factor Pre-regulator (PFP) uses a bulk energy storage capacitor, which is subjected to wear out at higher altitudes due to low pressure conditions and freezes at negative temperatures, resulting in poor reliability converter for Aerospace applications. Unlike a regular Power Factor Pre-regulator (PFP), the proposed topology avoids the use of bulk energy storage capacitor which results in a fast transient response with enhanced reliability, reduced board real estate and weight.

LED

Single Stage Power Factor The proposed LED driver topology can control the LED current with both Buck and Boost mode of control, making it a good choice for applications with wide input voltage variation. A 110 W prototype based on proposed converter was built to verify the operation of proposed topology. The experimental results are in line with the predicted performance. The proposed converter is able to achieve a power factor of 0.988 with an input current THD of < 10%.

SOFTWARE: MATLAB/SIMULINK

CONVENTIONAL DIAGRAM:

Figure 1. Single Stage Power Factor Conventional two stage active PFC based LED driver topology

EXPECTED SIMULATION RESULTS:

Figure 2. Single Stage Power Factor Measured waveforms at 90V AC input (a) Input Voltage (Red) (b) Input current (Blue) (c) Average Voltage drop across LED current sense resistor (green) (Equivalent to LED average current as the sense resistor value is 1ohm.

Figure 3. Single Stage Power Factor Measured Linear FFT of input current

Figure 4. Single Stage Power Factor Start-up transient at 90V AC input (a) Input Voltage (Red) (b) Input current (Blue) (c)  Average Voltage drop across LED current sense  resistor (Green)(Equivalent to LED average current  as the sense resistor value is 1ohm.

Figure 5. Single Stage Power Factor Current profiles through various power circuit components (a) LED Current (Green) (b) Current through MOSFET M1 (Red) (c) Current through inductor L2 (Blue) (d) Current through Inductor L1 (Purple)

Figure 6. Single Stage Power Factor Current profiles through various power circuit components (a) LED Current (Green) (b) Current through MOSFET M1 (Red) (c) Current through inductor L2 (Blue) (d) Current through Inductor L1 (Purple)

Figure 7. Single Stage Power Factor Measured waveforms at 132V AC input (a) Input Voltage (Light Blue) (b) Input current (Blue) (c) Average Voltage drop across LED current sense resistor (Red).

CONCLUSION:

Single Stage Power Factor This paper presents a novel LED driver topology, capable of input power factor correction, for space constrained applications, such as Aerospace exterior lighting product line. Due to the compact design of the proposed LED driver topology, it can be of great advantage for an integrated power supply solution for Aerospace exterior lighting product offerings.

LED

Single Stage Power Factor The proposed LED driver topology can control the LED current with both Buck and Boost mode of control, making it a good choice for applications with wide input voltage variation. The proposed LED driver topology has been verified by mathematical analysis, circuit simulation and performance has been demonstrated experimentally as well.

The proposed LED driver topology promises an appreciable amount of savings in term of real estate, power loss, and heat sink requirements while enhancing the power density of the converter and its reliability.

BOOST

Single Stage Power Factor Typically, it’s the bulk output capacitor that wears out with pressure variation (wear out phenomenon accelerates at altitudes more than 8000m due to the reduced pressures); which can be avoided with the proposed topology. Depending upon the load (number of LEDs) and input voltage; in order to protect LEDs.

A reverse blocking diode may be required during the Buck operation. For Boost application, reverse blocking diode will not be required even with today’s technology. Authors have been granted a U.S. Patent 9363291 [8] against the proposed novel LED driver topology.

REFERENCES:

[1] L. H. Dixon, “High Power Factor Preregulators for Off- Line Power Supplies,” Unitrode Power Supply Design Seminar Manual SEM600, 1988. (Republished in subsequent Manuals)

[2] Spiazzi, G., and Mattavelli, P. (1994) “Design criteria for power factor preregulators based on SEPIC and Cuk converters in continuous conduction mode,” IEEE IAS Conference Record, 1994, 1084-1089.

[3] Z. Ye, F. Greenfeld, and Z. Liang, “Single-stage offline SEPIC converter with power factor correction to drive high brightness LEDs,” in Proc. IEEE Appl. Power Electron. Conf., 2009, pp. 546–553.

[4] C.Zhou and M.Jovanovic, “Design Trade-offs in Continuous Current-Mode Controlled Boost Power-Factor Correction Circuits”, HFPC Cod. Proc., 1992, pp. 209-220

[5] L. H. Dixon, “Average Current Mode Control of Switching Power Supplies,” Unitrode Power Supply Design Seminar Manual SEM700, 1990

Initial Rotor Position Detection for Brushless DC Motors Based on Coupling Injection of High-Frequency Signal

ABSTRACT:

In applications where motor inversion is forbidden, it is important to detect the initial rotor position of the motor. For this reason, based on coupling injection of high-frequency signal, a novel method of initial rotor position detection for brushless DC motors (BLDCM) is proposed in this paper.

Firstly, the proposed method detects the relationship between three-phase winding inductances by injecting the high-frequency detection signal into motor windings in a coupling way, and the initial rotor position is determined into two sectors with 180 degrees electric angle difference.

Then, the polarity of the permanent magnet rotor is determined by applying two opposite voltage vectors to motor windings, so that the initial rotor position is determined into a unique sector, and the positioning accuracy is 30 degrees electric angle.

The proposed method significantly reduces the amplitude of the detection signal while increases its frequency by the way of coupling injection, thus reducing the response current and electromagnetic torque generated by the high-frequency signal and reducing the possibility of rotor inversion. Finally, the effectiveness of the proposed method is verified by experimental results.

KEYWORDS:

  1. Brushless DC motor
  2.  Initial rotor position
  3. High-frequency signal
  4. Coupling injection

SOFTWARE: MATLAB/SIMULINK

BLOCK DOAGRAM:

Figure 1 Equivalent Circuit Of System When The High-Frequency Detection Signal Is Injected Into Phase A And B.

EXPECTED SIMULATION RESULTS:

Figure 2. Experimental Waveforms With The Rotor Located At 195 Degree. (A) Step I. (B) Step Ii.

Figure 3. Experimental Waveforms With The Rotor Located At 52 Degree. (A) Step I. (B) Step Ii.

Figure 4. Result Of Rotor Position Detection Based On The Proposed Method.

Figure 5. Electromagnetic Torque Of Two Methods When The Rotor Locates At 195 Degree. (A) Method In [13]. (B) Proposed Method.

Figure 6. Electromagnetic Torque Of Two Methods When The Rotor Locates At 52 Degree. (A) Method In [13]. (B) Proposed Method.

Figure 7. Maximum Electromagnetic Torque Of Two Methods When The Rotor Locates At Different Positions.

CONCLUSION:

Initial Rotor Position Detection In this paper, the relationship between winding inductances and the rotor position of BLDCM is analyzed in detail, and a novel method of initial rotor position detection based on high-frequency signal coupling injection is proposed. The initial rotor position can be determined into a sector with 30 degrees electric angle.

Initial Rotor Position Detection The proposed method overcomes the limitations of fixed DC-link voltage and limited switching frequency of the inverter by the way of coupling injection, and significantly reduces the amplitude of the detection signal while increases its frequency. Experimental results show that, compared with traditional methods

Initial Rotor Position Detection the method proposed in this paper can accurately detect the initial rotor position and effectively reduce the electromagnetic torque, thus reducing the possibility of rotor inversion in the process of initial position detection.

REFERENCES:

[1] K. Liu, Z. Zhou, and W. Hua, “A novel region-re_nement pulse width modulation method for torque ripple reduction of brushless DC motors,” IEEE Access, vol. 7, pp. 5333_5342, 2019. doi: 10.1109/ACCESS.2018.2888630.

[2] C. Xia, G. Jiang,W. Chen, and T. Shi, “Switching-gain adaptation current control for brushless DC motors,” IEEE Trans. Ind. Electron., vol. 63, no. 4, pp. 2044_2052, Apr. 2016. doi: 10.1109/TIE.2015.2506144.

[3] C. Xia, Y. Wang, and T. Shi, “Implementation of _nite-state model predictive control for commutation torque ripple minimization of permanent- magnet brushless DC motor,” IEEE Trans. Ind. Electron., vol. 60, no. 3, pp. 896_905, Mar. 2013. doi: 10.1109/TIE.2012.2189536.

[4] B. Tan, X. Wang, D. Zhao, K. Shen, J. Zhao, and X. Ding, “A lag angle compensation strategy of phase current for high- speed BLDC motors,” IEEE Access, vol. 7, pp. 9566_9574, 2019. doi: 10.1109/ACCESS.2018.2887106.

[5] J. Shao, “An improved microcontroller-based sensorless brushless DC (BLDC) motor drive for automotive applications,” IEEE Trans. Ind. Appl.,vol. 42, no. 5, pp. 1216_1221, Sep. 2006. doi: 10.1109/TIA.2006.880888.

Front-End Buck Rectifier With Reduced Filter Size and Single-Loop Control

ABSTRACT:

Buck Rectifier a transformerless solution for front-end rectification, which is particularly suitable for traction applications, requiring high voltages to be stepped down to appropriate dc voltage. The proposed topology is based on pulse width modulation buck rectifier (current source inverter topology) and is capable of rectification and stepping down of single-phase ac supply, in a single stage.

DC INDUCTOR

Buck Rectifier A new control scheme is proposed to achieve constant dc output voltage and sinusoidal source current, irrespective of large ripples in the dc inductor current. Buck Rectifier The proposed scheme is configured in single-loop voltage control mode. The relevant small-signal model is derived from the large-signal model using multi order decomposition.

Buck Rectifier An elaborate procedure of dc filter design is discussed, for circuit operation with minimum energy storage. All analytical results are validated by numerical simulation for sinusoidal and distorted source voltage. Experimental verification is achieved through a 1.2-kW grid-connected laboratory prototype.

KEYWORDS:

  1. Buck rectifier (BR)
  2. Single-loop control
  3. Single phase
  4. Traction
  5. Transformerless

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Basic BR circuit.

EXPECTED SIMULATION RESULTS:

Fig. 2. (a) Simulation results: Steady-state operation. vs (160 V/div); is (5 A/div); idc (5 A/div); vo (160 V/div); time (5 ms/div). (b) Harmonic spectrum of is (percentage of fundamental).

Fig. 3. (a) Simulation results: Steady-state operation at boundary condition. vs (160 V/div); is (5 A/div); idc (5 A/div); is1 (5 A/div); time (5 ms/div). (b) Harmonic spectrum of is (percentage of rated fundamental).

Fig. 4. Simulation results: Dynamic performance with step change in vo reference. idc (8 A/div); vo (25 V/div); vo (25 V/div); time (40 ms/div).

Fig. 5. Simulation results: Dynamic performance with step change in vs. vs (200 V/div); is (10 A/div); idc (5 A/div); vo (100 V/div); time (20 ms/div).

Fig. 6. Simulation results with distorted source. (a) vs (120 V/div); is (5 A/div); time (5 ms/div). (b) Harmonic spectrum of is (percentage of fundamental).

CONCLUSION:

Buck Rectifier a single-loop control scheme for single-phase BR has been presented. A nonlinear modulation scheme is proposed, and its effect is analyzed using a multi order system decomposition. The effectiveness of the proposed scheme is proved by simulation and experimental results.

UPF OPERATION

Buck Rectifier From experimental results, it is clear that the proposed control scheme is capable of maintaining sinusoidal source current and near-UPF operation with optimum filter volume, even under distorted grid conditions. Generalized design of the dc inductor, which is the most critical element, is presented in detail.

Buck Rectifier Since source current wave shape is maintained despite ripples in dc current, requirement of an inner current loop is rendered superfluous. Apart from justifying the single-loop control scheme, this also entails greatly simplified controller design and realization.

REFERENCES:

[1] M. Brenna, F. Foiadelli, and D. Zaninelli, “New stability analysis for tuning PI controller of power converters in railway application,” IEEE Trans. Ind. Electron., vol. 58, no. 2, pp. 553–543, Feb. 2011.

[2] M. Carpita, M. Marchesoni, M. Pellerin, and D. Moser, “Multilevel converter for traction applications: Small-scale prototype test results,” IEEE Trans. Ind. Electron., vol. 55, no. 5, pp. 2203–2212,May 2008.

[3] P. Drabek, Z. Peroutka, M. Pitterman, and M. Cedl, “New configuration of traction converter with medium-frequency transformer using matrix converters,” IEEE Trans. Ind. Electron., vol. 58, no. 11, pp. 5041–5048, Nov. 2011.

[4] A. Rufer, N. Schibli, C. Chabert, and C. Zimmermann, “Configurable front-end converters for multicurrent locomotives operated on 16 2/3 Hz and 3 kV DC systems,” IEEE Trans. Power Electron., vol. 18, no. 5, pp. 1186–1193, Sep. 2003.

[5] S. Dieckerhoff, S. Bernet, and D. Krug, “Power loss-oriented evaluation of high voltage IGBTs and multilevel converters in transformerless traction applications,” IEEE Trans. Power Electron., vol. 20, no. 6, pp. 1328–1336,Nov. 2005.

Low Switching Frequency based Asymmetrical Multilevel Inverter Topology with Reduced Switch Count

ABSTRACT:

Multilevel inverters (MLI) since its inception have caught the attention of researchers for medium and high power application. However, there has always been a need for a topology with a lower number of device count for higher efficiency and reliability. A new single phase MLI topology has been proposed in this paper to reduce the number of switches in the circuit and obtain higher voltage level at the output. The basic unit of the proposed topology produces 13 level at the output with three dc voltage sources and eight switches. Three extention of the basic unit have been proposed in this paper. A detailed analysis of the proposed topology has been carried out to show the superiority of the proposed converter with respect to the other existing MLI topologies. Power loss analysis has been done using PLECS software, results in maximum efficiency of 98.5%. Nearest level control (NLC) pulse width modulation technique has been used to produce gate pulses for the switches to achieve better output voltage waveform. The various simulation results have been performed in the PLECS software and a laboratory setup has been used to shows the feasibility of the proposed MLI topology.

KEYWORDS:

  1. DC-AC converter
  2. Multilevel inverter
  3. Reduce switch count
  4. Nearest level control (NLC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Basic unit of the proposed topology

EXPECTED SIMULATION RESULTS:

Figure 2. Simulation results with (a) dynamic change of modulation index (b) FFT of 13 level output voltage and current with Z=10Ω+100mH and (c) output voltage and current waveforms with change of load from Z=50Ω to Z=50Ω+100Mh

CONCLUSION:

The paper presents a novel MLI topology with multiple extension capabilities. The basic unit of the proposed topology produces 13 levels using eight unidirectional switches and three dc voltage sources. Three different extension of the basic unit has been proposed. The performance analysis of the basic unit of the proposed topology has been done and the comparative results with some recently proposed topologies in literature have been presented in the paper. Further, a power loss analysis of the dynamic losses (switching and conduction) in the MLI has also been presented, which gives the maximum efficicnecy of the basic unit as 98.5%. The power loss distribution in all the switches for different combination of loads have also been demonstrated in the paper. The performance of the proposed topology has been simulated with dynamic modulation indexes and different combination of loads using PLECS sorftware. A prototype of the basic unit has been developed in the laboratory and the simulation results have been validated using the different expriemntal results considering different modulation indexes.

REFERENCES:

[1] S. Kouro et al., “Recent Advances and Industrial Applications of Multilevel Converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553–2580, 2010.

[2] H. Abu-Rub, J. Holtz, J. Rodriguez, and Ge Baoming, “Medium-Voltage Multilevel Converters—State of the Art, Challenges, and Requirements in Industrial Applications,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2581–2596, Aug. 2010.

[3] H. Akagi, “Multilevel Converters: Fundamental Circuits and Systems,” Proc. IEEE, vol. 105, no. 11, pp. 2048–2065, Nov. 2017.

[4] J. I. Leon, S. Vazquez, and L. G. Franquelo, “Multilevel Converters: Control and Modulation Techniques for Their Operation and Industrial Applications,” Proc. IEEE, vol. 105, no. 11, pp. 2066–2081, Nov. 2017.

[5] J. Venkataramanaiah, Y. Suresh, and A. K. Panda, “A review on symmetric, asymmetric, hybrid and single DC sources based multilevel inverter topologies,” Renew. Sustain. Energy Rev., vol. 76, pp. 788–812, Sep. 2017.

Intelligent Energy Control Center for Distributed Generators Using Multi-Agent System

ABSTRACT:

This paper presents the modeling of intelligent energy control center (ECC) controlling distributed generators (DGs) using multi- agent system. Multi-agent system has been proposed to provide intelligent energy control and management in grids because of their benefits of extensibility, autonomy, reduced maintenance, etc. The multi -agent system constituting the smart grid and agents such as user agent, control agent, database agent, distributed energy resources (DER) agent work in collaboration to perform assigned tasks. The wind power generator connected with local load, the solar power connected with local load and the ECC controlled by fuzzy logic controller (FLC) are simulated in MATLAB/SIMULINK. The DER model is created in client and ECC is created in server. Communication between the server and the client is established using transmission control protocol/internet protocol (TCP/IP). The results indicate that the controlling of DER agent can be achieved both from server and client.

KEYWORDS:

  1. Distributed energy resources (DER) and trans-mission control protocol/internet protocol (TCP/IP)
  2. Distributed generators (DGs)
  3. Energy control center (ECC)
  4. Fuzzy logic controller (FLC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of ECC.

EXPECTED SIMULATION RESULTS:

Fig. 2. Voltage waveform of wind and solar power – circuit breaker (CB-1) closed after 0.1 s and circuit breaker (CB-2) closed after 0.3 s to interconnect solar power to wind.

Fig. 3. Voltage waveform of wind and solar power circuit breaker (CB-1) closed after 0.1 s and circuit breaker (CB-2) closed after 0.3 s to interconnect solar power to wind observed up to 0.6 s.

Fig. 4. Three-phase voltage waveform of the power system.

Fig. 5. Three-phase current waveform of the power system.

Fig. 6. System frequency waveform of the power system.

CONCLUSION:

The simulation model of ECC, controlling the solar power generation and wind power generation interconnected with grid using multi-agent system is described in this paper. The voltage of wind and solar power are stored in a excel sheet as a database agent. Intelligent controller the switch provided in the solar panel to add/remove depending upon the voltage requirements. This excel sheet acting as a monitoring tool to access the simulation results, provides the visualization of the grid. The results prove that the multi-agent component controls the Distributed Energy Resources.

REFERENCES:

[1] T. Nagata and H. Sasaki, “A multi-agent approach to power system restoration,” IEEE Trans. Power Syst., vol. 17, no. 2, pp. 457–462, May 2002.

[2] T. A. Dimeas and N. D. Hatziargyriou, “Operation of a multiagent system for microgrid control,” IEEE Trans. Power Syst., vol. 20, no. 3, pp. 1447–1455, Aug. 2005.

[3] S. G. Ankaliki, “Energy control center functions for power system,” Int. J. Math. Sci., Technol., Humanities, vol. 2, no. 1, pp. 205– 212, 2012

[4] R. L. Krutz, Securing SCADA Systems. New York, NY, USA: Wiley, 2006.

[5] O. Castillo and P. melin, Studies in Fuzziness and Soft Computing Type2 Fuzzy Logic : Theory and Applications. New York, NY, USA: Springer-Verlag, 2008.