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Volume 51,Issue 12,2024 Table of Contents
2024, 51(12):1-12.
DOI: 10.12177/emca.2024.133
Abstract:
[Objective] Power devices composed of first- and second-generation semiconductor materials have reached their performance limits, making them unsuitable for more complex circuit topologies. Silicon carbide (SiC), the third-generation semiconductor material, has gradually become a research focus, and corresponding SiC devices are now at the forefront of research. Compared to traditional silicon (Si)-based devices, silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) offer superior characteristics and are widely used in high-voltage, high-frequency, and high-power-density applications. However, due to the limited current-carrying capacity of a single device, multiple devices are often used in parallel. Immature manufacturing processes and asymmetric circuit layouts cause differences in device parameters and external circuit parameters, leading to unbalanced current issues. To address this problem, this paper proposes a current-sharing control strategy. [Methods] This paper first analyzed and summarized the factors affecting parallel current sharing and determined the influence of each parameter. Based on the devices’ switching characteristics, theoretical formulas were derived to summarize the current variation patterns. Then, a corresponding current detection circuit was designed to accurately capture current differences. Finally, a current-sharing control strategy based on adjusting multi-level driving resistance was proposed to gradually regulate unbalanced currents. [Results] Simulation results validated the effectiveness of the proposed control strategy, significantly reducing current imbalance. [Conclusion] The results show that by setting an appropriate driving resistance, the proposed control strategy can effectively achieve current sharing in dual-device parallel configurations.
[Objective] Power devices composed of first- and second-generation semiconductor materials have reached their performance limits, making them unsuitable for more complex circuit topologies. Silicon carbide (SiC), the third-generation semiconductor material, has gradually become a research focus, and corresponding SiC devices are now at the forefront of research. Compared to traditional silicon (Si)-based devices, silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) offer superior characteristics and are widely used in high-voltage, high-frequency, and high-power-density applications. However, due to the limited current-carrying capacity of a single device, multiple devices are often used in parallel. Immature manufacturing processes and asymmetric circuit layouts cause differences in device parameters and external circuit parameters, leading to unbalanced current issues. To address this problem, this paper proposes a current-sharing control strategy. [Methods] This paper first analyzed and summarized the factors affecting parallel current sharing and determined the influence of each parameter. Based on the devices’ switching characteristics, theoretical formulas were derived to summarize the current variation patterns. Then, a corresponding current detection circuit was designed to accurately capture current differences. Finally, a current-sharing control strategy based on adjusting multi-level driving resistance was proposed to gradually regulate unbalanced currents. [Results] Simulation results validated the effectiveness of the proposed control strategy, significantly reducing current imbalance. [Conclusion] The results show that by setting an appropriate driving resistance, the proposed control strategy can effectively achieve current sharing in dual-device parallel configurations.
2024, 51(12):13-25.
DOI: 10.12177/emca.2024.142
Abstract:
[Objective] Since the introduction of the dual carbon goals, the rapid development of renewable energy has led to an increasing application of inverters in power systems. Hysteresis current control offers advantages such as fast response and simple control, and it has been widely used in inverter control. However, traditional hysteresis current control requires high accuracy of the reference voltage vector sector, and sector switching can easily lead to uncontrollable error currents due to sector misjudgment. To address this, a hysteresis current control strategy based on fixed switch state switching is proposed. [Methods] In the three-level hysteresis current control method, there are various ways to divide the sectors. By combining different sector division methods in the hysteresis control of three-level inverters, the disadvantage of traditional hysteresis control, where both the sector and the control strategy should be updated at sector boundaries, was effectively avoided. This method allowed for errors in sector judgement of the reference voltage vector while ensuring the error current was controlled throughout the entire cycle. With a fixed loop width, the switching frequency was variable, leading to increased switching losses. Therefore, a frequency-fixed control strategy was studied under this approach. By obtaining the error current data from the previous cycle, the hysteresis width for the current cycle was updated to achieve fixed frequency control, and the calculation formula for the next cycle’s hysteresis width was provided. [Results] The method was validated through Matlab/Simulink simulations. The simulation results showed that the proposed method ensured the error current was controlled throughout the entire cycle, even when the reference voltage vector was at the boundaries of sector switching, and the switching frequency remained around 20 kHz. [Conclusion] The proposed frequency-fixed hysteresis current control strategy based on fixed switch state switching aligns well with the theoretical results and demonstrats accuracy.
[Objective] Since the introduction of the dual carbon goals, the rapid development of renewable energy has led to an increasing application of inverters in power systems. Hysteresis current control offers advantages such as fast response and simple control, and it has been widely used in inverter control. However, traditional hysteresis current control requires high accuracy of the reference voltage vector sector, and sector switching can easily lead to uncontrollable error currents due to sector misjudgment. To address this, a hysteresis current control strategy based on fixed switch state switching is proposed. [Methods] In the three-level hysteresis current control method, there are various ways to divide the sectors. By combining different sector division methods in the hysteresis control of three-level inverters, the disadvantage of traditional hysteresis control, where both the sector and the control strategy should be updated at sector boundaries, was effectively avoided. This method allowed for errors in sector judgement of the reference voltage vector while ensuring the error current was controlled throughout the entire cycle. With a fixed loop width, the switching frequency was variable, leading to increased switching losses. Therefore, a frequency-fixed control strategy was studied under this approach. By obtaining the error current data from the previous cycle, the hysteresis width for the current cycle was updated to achieve fixed frequency control, and the calculation formula for the next cycle’s hysteresis width was provided. [Results] The method was validated through Matlab/Simulink simulations. The simulation results showed that the proposed method ensured the error current was controlled throughout the entire cycle, even when the reference voltage vector was at the boundaries of sector switching, and the switching frequency remained around 20 kHz. [Conclusion] The proposed frequency-fixed hysteresis current control strategy based on fixed switch state switching aligns well with the theoretical results and demonstrats accuracy.
2024, 51(12):26-38.
DOI: 10.12177/emca.2024.137
Abstract:
[Objective] As the proportion of renewable energy in the power system continues to rise, grid-forming converters have garnered significant attention and research interest due to their superior voltage support capabilities. However, in remote low-voltage distribution networks, the ratio of line resistance-inductance is relatively high. This can lead to power coupling issues in grid-forming converters, adversely impacting their fundamental voltage support and power transmission capabilities. This paper addresses the power coupling issues in grid-forming converters, considering changes in the resistance-inductance ratio in distribution networks. A control strategy employing feedforward decoupling is proposed. [Methods] The robustness of the system was improved by adding low-pass filter (LPF) into the decoupling channel. The impact of different LPF bandwidths on system stability was analyzed using the small signal method. [Results] Upon implementing feedforward decoupling, the coupling between the active and reactive power control loops was significantly reduced, effectively resolving the power coupling issues caused by the high resistance-inductance ratio of the distribution network. [Conclusion] The proposed method can achieve effective decoupling and provides a highly robust control strategy for power transmission in grid-forming converters.
[Objective] As the proportion of renewable energy in the power system continues to rise, grid-forming converters have garnered significant attention and research interest due to their superior voltage support capabilities. However, in remote low-voltage distribution networks, the ratio of line resistance-inductance is relatively high. This can lead to power coupling issues in grid-forming converters, adversely impacting their fundamental voltage support and power transmission capabilities. This paper addresses the power coupling issues in grid-forming converters, considering changes in the resistance-inductance ratio in distribution networks. A control strategy employing feedforward decoupling is proposed. [Methods] The robustness of the system was improved by adding low-pass filter (LPF) into the decoupling channel. The impact of different LPF bandwidths on system stability was analyzed using the small signal method. [Results] Upon implementing feedforward decoupling, the coupling between the active and reactive power control loops was significantly reduced, effectively resolving the power coupling issues caused by the high resistance-inductance ratio of the distribution network. [Conclusion] The proposed method can achieve effective decoupling and provides a highly robust control strategy for power transmission in grid-forming converters.
LI Yaohua
,
CHONG Guochen
,
LIU Zikun
,
ZHANG Xinquan
,
GUO Weichao
,
GAO Sai
,
WANG Qinzheng
,
WANG Zichen
,
XU Zhixiong
,
DONG Guoqing
2024, 51(12):39-50.
DOI: 10.12177/emca.2024.141
Abstract:
[Objective] One-step and two-step model-free predictive current control (MFPCC) for permanent magnet synchronous motor (PMSM) system is established to address the strong parameter dependence issue in model predictive current control (MPCC). [Method] Based on the ultralocal model, one-step and two-step MFPCC for PMSM was implemented. The differential algebraic method was used to estimate uncertain parts of the first-order and second-order ultralocal models. The effect of the window sequence length of the ultralocal model on control performance was analyzed, along with the parameter robustness of the ultralocal model-based one-step and two-step MFPCC for PMSM with parameter variations. Real-time experiments were conducted to verify the results. [Results] Simulation and real-time experimental results showed that the window sequence length of the first-order ultralocal model significantly impacted the control performance. Increasing the window sequence length improved control performance until saturation. The window sequence length of the second-order ultralocal model had a smaller effect on control performance. The ultralocal model-based one-step and two-step MFPCC for PMSM showed strong parameter robustness with parameter variations. With the increase in window sequence length, the computational time for the ultralocal model increased slightly, but the overall real-time performance was minimally affected. [Conclusion] The ultralocal model-based one-step and two-step MFPCC for PMSM is feasible and demonstrates strong parameter robustness. The real-time performance of the ultralocal model-based one-step MFPCC is comparable to that of the conventional one-step MPCC. The ultralocal model-based two-step MFPCC exhibits slightly better real-time performance than the conventional two-step MPCC.
[Objective] One-step and two-step model-free predictive current control (MFPCC) for permanent magnet synchronous motor (PMSM) system is established to address the strong parameter dependence issue in model predictive current control (MPCC). [Method] Based on the ultralocal model, one-step and two-step MFPCC for PMSM was implemented. The differential algebraic method was used to estimate uncertain parts of the first-order and second-order ultralocal models. The effect of the window sequence length of the ultralocal model on control performance was analyzed, along with the parameter robustness of the ultralocal model-based one-step and two-step MFPCC for PMSM with parameter variations. Real-time experiments were conducted to verify the results. [Results] Simulation and real-time experimental results showed that the window sequence length of the first-order ultralocal model significantly impacted the control performance. Increasing the window sequence length improved control performance until saturation. The window sequence length of the second-order ultralocal model had a smaller effect on control performance. The ultralocal model-based one-step and two-step MFPCC for PMSM showed strong parameter robustness with parameter variations. With the increase in window sequence length, the computational time for the ultralocal model increased slightly, but the overall real-time performance was minimally affected. [Conclusion] The ultralocal model-based one-step and two-step MFPCC for PMSM is feasible and demonstrates strong parameter robustness. The real-time performance of the ultralocal model-based one-step MFPCC is comparable to that of the conventional one-step MPCC. The ultralocal model-based two-step MFPCC exhibits slightly better real-time performance than the conventional two-step MPCC.
2024, 51(12):51-59.
DOI: 10.12177/emca.2024.129
Abstract:
[Objective] To address the issues of slow response speed, low observation accuracy, and poor anti-disturbance capability in trajectory observation for permanent magnet synchronous motor (PMSM) position and speed estimation using traditional extended state observers (ESO), an improved ESO trajectory observer based on adaptive acceleration compensation is proposed. [Methods] Adaptive acceleration feedforward compensation was introduced into the traditional ESO, enabling online adaptive adjustment of the feedforward acceleration based on position observation errors. This enhancement improved the dynamic accuracy and response speed of trajectory observation under strong disturbance and transient operating conditions. [Results] Simulation results showed that the proposed improved ESO trajectory observer reduced the position observation error by 61.53% and the angular velocity observation error by 58.6% compared to the traditional ESO-based observation method under strong disturbance and transient conditions. [Conclusion] The proposed improved ESO trajectory observer effectively enhances response speed, dynamic accuracy, and anti-disturbance capability in trajectory observation. With excellent observation performance, it offers significant engineering application value.
[Objective] To address the issues of slow response speed, low observation accuracy, and poor anti-disturbance capability in trajectory observation for permanent magnet synchronous motor (PMSM) position and speed estimation using traditional extended state observers (ESO), an improved ESO trajectory observer based on adaptive acceleration compensation is proposed. [Methods] Adaptive acceleration feedforward compensation was introduced into the traditional ESO, enabling online adaptive adjustment of the feedforward acceleration based on position observation errors. This enhancement improved the dynamic accuracy and response speed of trajectory observation under strong disturbance and transient operating conditions. [Results] Simulation results showed that the proposed improved ESO trajectory observer reduced the position observation error by 61.53% and the angular velocity observation error by 58.6% compared to the traditional ESO-based observation method under strong disturbance and transient conditions. [Conclusion] The proposed improved ESO trajectory observer effectively enhances response speed, dynamic accuracy, and anti-disturbance capability in trajectory observation. With excellent observation performance, it offers significant engineering application value.
2024, 51(12):60-70.
DOI: 10.12177/emca.2024.138
Abstract:
[Objective] Under the dual-carbon target, coal-fired units are transitioning from operating under long-term stable loads to flexible operation. The deep peak shaving capability has become a critical indicator of the flexibility of coal-fired power units. However, deep peak shaving operations lead to rapid changes in the generator's hotspot temperatures, causing faults such as winding deformation, insulation wear, delamination, and wedge loosening. This paper investigates the operating state of the stator end of generators under deep peak shaving conditions. [Methods] Using COMSOL Multiphysics finite element analysis software, a multi-physics field coupling model for the stator winding was established, integrating electrical, magnetic, and mechanical fields. The vibration displacement of conductor bars and wedges was analyzed under two deep peak shaving conditions: rapid load variation and ultra-low load. Furthermore, to accelerate the adaptability of generators to deep peak shaving operation, two stator end structure optimization schemes were proposed. [Results] Simulation results showed that when the load changed at a rate of 5%/min, the vibration amplitudes of the straight section conductor bars, wedges, and slot exit conductor bars decreased by 21.19%, 99.7%, and 59.05%, respectively, compared to the original structure under rated conditions. When the generator operated at 30% load, the displacement reductions were 72.46%, 99.997%, and 53.85%, respectively. [Conclusion] After structural optimization, the displacement amplitudes of the straight section conductor bars, wedges and slot exit conductor bars under extreme rapid load variation conditions are significantly reduced, confirming the effectiveness of the optimized structure.
[Objective] Under the dual-carbon target, coal-fired units are transitioning from operating under long-term stable loads to flexible operation. The deep peak shaving capability has become a critical indicator of the flexibility of coal-fired power units. However, deep peak shaving operations lead to rapid changes in the generator's hotspot temperatures, causing faults such as winding deformation, insulation wear, delamination, and wedge loosening. This paper investigates the operating state of the stator end of generators under deep peak shaving conditions. [Methods] Using COMSOL Multiphysics finite element analysis software, a multi-physics field coupling model for the stator winding was established, integrating electrical, magnetic, and mechanical fields. The vibration displacement of conductor bars and wedges was analyzed under two deep peak shaving conditions: rapid load variation and ultra-low load. Furthermore, to accelerate the adaptability of generators to deep peak shaving operation, two stator end structure optimization schemes were proposed. [Results] Simulation results showed that when the load changed at a rate of 5%/min, the vibration amplitudes of the straight section conductor bars, wedges, and slot exit conductor bars decreased by 21.19%, 99.7%, and 59.05%, respectively, compared to the original structure under rated conditions. When the generator operated at 30% load, the displacement reductions were 72.46%, 99.997%, and 53.85%, respectively. [Conclusion] After structural optimization, the displacement amplitudes of the straight section conductor bars, wedges and slot exit conductor bars under extreme rapid load variation conditions are significantly reduced, confirming the effectiveness of the optimized structure.
2024, 51(12):71-80.
DOI: 10.12177/emca.2024.131
Abstract:
[Objective] To address the issue of metaheuristic algorithms being prone to falling into local optima during the parameter identification process of permanent magnet synchronous motor (PMSM), an improved Spider Monkey optimization (SMO) algorithm based on Tent chaotic mapping and nonlinear dynamic adaptive weights is proposed. This algorithm aims to achieve accurate identification of internal parameters of PMSM. [Methods] By introducing Tent chaotic mapping in the initialization phase of the algorithm, the probability of finding the optimal solution in the early stage was increased. In the local leader stage, dynamic adaptive weights were introduced based on the population’s fitness values in the current iteration to meet the next generation population’s needs for global exploration and local optimization. [Results] Simulation results showed that the improved SMO algorithm based on Tent chaotic mapping and nonlinear dynamic adaptive weights had improved convergence speed and identification accuracy during the identification process, with errors controlled within approximately 0.5%. [Conclusion] The proposed improved SMO algorithm exhibits faster identification speed, higher accuracy, and good convergence characteristics.
[Objective] To address the issue of metaheuristic algorithms being prone to falling into local optima during the parameter identification process of permanent magnet synchronous motor (PMSM), an improved Spider Monkey optimization (SMO) algorithm based on Tent chaotic mapping and nonlinear dynamic adaptive weights is proposed. This algorithm aims to achieve accurate identification of internal parameters of PMSM. [Methods] By introducing Tent chaotic mapping in the initialization phase of the algorithm, the probability of finding the optimal solution in the early stage was increased. In the local leader stage, dynamic adaptive weights were introduced based on the population’s fitness values in the current iteration to meet the next generation population’s needs for global exploration and local optimization. [Results] Simulation results showed that the improved SMO algorithm based on Tent chaotic mapping and nonlinear dynamic adaptive weights had improved convergence speed and identification accuracy during the identification process, with errors controlled within approximately 0.5%. [Conclusion] The proposed improved SMO algorithm exhibits faster identification speed, higher accuracy, and good convergence characteristics.
2024, 51(12):81-92.
DOI: 10.12177/emca.2024.139
Abstract:
[Objective] To solve the problems of reduced control accuracy in permanent magnet synchronous motor (PMSM) speed control systems due to variations in motor parameters and external disturbances, a model-free sliding mode control method for the PMSM speed loop based on adaptive gain is investigated. [Methods] The mathematical model of PMSM under internal parameter changes and load disturbance was constructed. The adaptive gain power reaching law was selected and combined with the model-free control concept to design a model-free sliding mode controller containing a disturbance term. The total motor disturbance was observed using a novel adaptive gain super-twisting sliding mode observer. [Results] With the help of Matlab/Simulink software and dSPACE platform for simulation and experimental comparison, the results demonstrated that the proposed method reduced the dynamic response time of the PMSM system, decreased the rotational speed fluctuation and the system chattering, and improved disturbance rejection ability and stability. [Conclusion] The proposed method can effectively improve the control accuracy of the PMSM speed loop, enhance the dynamic response of the system, inhibit chattering, and improve robustness.
[Objective] To solve the problems of reduced control accuracy in permanent magnet synchronous motor (PMSM) speed control systems due to variations in motor parameters and external disturbances, a model-free sliding mode control method for the PMSM speed loop based on adaptive gain is investigated. [Methods] The mathematical model of PMSM under internal parameter changes and load disturbance was constructed. The adaptive gain power reaching law was selected and combined with the model-free control concept to design a model-free sliding mode controller containing a disturbance term. The total motor disturbance was observed using a novel adaptive gain super-twisting sliding mode observer. [Results] With the help of Matlab/Simulink software and dSPACE platform for simulation and experimental comparison, the results demonstrated that the proposed method reduced the dynamic response time of the PMSM system, decreased the rotational speed fluctuation and the system chattering, and improved disturbance rejection ability and stability. [Conclusion] The proposed method can effectively improve the control accuracy of the PMSM speed loop, enhance the dynamic response of the system, inhibit chattering, and improve robustness.
2024, 51(12):93-102.
DOI: 10.12177/emca.2024.130
Abstract:
[Objective] Fractional slot concentrated winding (FSCW) has the advantages of high torque density and low copper consumption, but its rich harmonic magnetic field and high proportion of low-order harmonics can cause torque ripple, affecting motor stability. This study focuses on FSCW induction motors. [Methods] Based on the initial rotor position, the expressions for each harmonic magnetic density in the air gap were deduced; the influence of each harmonic magnetic density on the total torque was qualitatively analyzed; and Maxwell variant was applied to calculate the electromagnetic torque of the motor. Secondly, through mathematical analysis and finite element simulation, the effects of the initial rotor position on the harmonic magnetic flux density in the air gap and the electromagnetic torque of the motor were analyzed. Finally, the prototype locked-rotor test was carried out. [Results] The correctness of the theoretical analysis of the magnetic flux density in the air gap and electromagnetic torque of the FSCW induction motor was verified based on theory, simulation, and experiment. [Conclusion] Starting the motor with different rotor initial positions can result in varying electromagnetic torque.
[Objective] Fractional slot concentrated winding (FSCW) has the advantages of high torque density and low copper consumption, but its rich harmonic magnetic field and high proportion of low-order harmonics can cause torque ripple, affecting motor stability. This study focuses on FSCW induction motors. [Methods] Based on the initial rotor position, the expressions for each harmonic magnetic density in the air gap were deduced; the influence of each harmonic magnetic density on the total torque was qualitatively analyzed; and Maxwell variant was applied to calculate the electromagnetic torque of the motor. Secondly, through mathematical analysis and finite element simulation, the effects of the initial rotor position on the harmonic magnetic flux density in the air gap and the electromagnetic torque of the motor were analyzed. Finally, the prototype locked-rotor test was carried out. [Results] The correctness of the theoretical analysis of the magnetic flux density in the air gap and electromagnetic torque of the FSCW induction motor was verified based on theory, simulation, and experiment. [Conclusion] Starting the motor with different rotor initial positions can result in varying electromagnetic torque.
2024, 51(12):103-112.
DOI: 10.12177/emca.2024.135
Abstract:
[Objective] The air-gap magnetic field of permanent magnet generators is non-adjustable, resulting in a limited output voltage regulation range. To achieve an adjustable air-gap magnetic field, this paper studies a hybrid excitation DC generator with a tangential flux-concentrating parallel structure. [Methods] A Maxwell 2D and Simplorer field-circuit coupling model was built. The no-load characteristics and no-load air-gap flux density were simulated by finite element method. The parameter selection of related components in the filter circuit was discussed. The external characteristics were calculated, and the air-gap flux density and adjustment characteristics under armature reaction were analyzed. [Results] The simulation results showed that, under a constant external characteristic load, when the excitation current increased from -12 A to 0 A, the terminal voltage rose by 3.02 V. Further increasing the excitation current from 0 A to 12 A resulted in a terminal voltage increase of 24.66 V. Under armature reaction conditions, the amplitudes of the fundamental wave, 5P and 7P harmonics components of the air-gap flux density decreased by 0.05 T, 0.02 T, and 0.01 T, respectively, while the amplitudes of the 3P and 9P harmonics increased by 0.09 T and 0.03 T, respectively. The air-gap flux density curve exhibited a trend where one half was strengthened while the other half was weakened. [Conclusion] The no-load characteristics indicate that applying positive excitation to the generator is more effective than negative excitation, making it suitable for low-speed and high-torque applications. The output voltage increases with higher rotational speeds. The external characteristic curve shows that, under negative excitation current, the variation in the generator's phase voltage root mean square value is relatively small, whereas under positive excitation current, the variation is significantly larger. In the adjustment characteristics, to maintain a constant generator terminal voltage, the excitation current must be increased as the load current increases.
[Objective] The air-gap magnetic field of permanent magnet generators is non-adjustable, resulting in a limited output voltage regulation range. To achieve an adjustable air-gap magnetic field, this paper studies a hybrid excitation DC generator with a tangential flux-concentrating parallel structure. [Methods] A Maxwell 2D and Simplorer field-circuit coupling model was built. The no-load characteristics and no-load air-gap flux density were simulated by finite element method. The parameter selection of related components in the filter circuit was discussed. The external characteristics were calculated, and the air-gap flux density and adjustment characteristics under armature reaction were analyzed. [Results] The simulation results showed that, under a constant external characteristic load, when the excitation current increased from -12 A to 0 A, the terminal voltage rose by 3.02 V. Further increasing the excitation current from 0 A to 12 A resulted in a terminal voltage increase of 24.66 V. Under armature reaction conditions, the amplitudes of the fundamental wave, 5P and 7P harmonics components of the air-gap flux density decreased by 0.05 T, 0.02 T, and 0.01 T, respectively, while the amplitudes of the 3P and 9P harmonics increased by 0.09 T and 0.03 T, respectively. The air-gap flux density curve exhibited a trend where one half was strengthened while the other half was weakened. [Conclusion] The no-load characteristics indicate that applying positive excitation to the generator is more effective than negative excitation, making it suitable for low-speed and high-torque applications. The output voltage increases with higher rotational speeds. The external characteristic curve shows that, under negative excitation current, the variation in the generator's phase voltage root mean square value is relatively small, whereas under positive excitation current, the variation is significantly larger. In the adjustment characteristics, to maintain a constant generator terminal voltage, the excitation current must be increased as the load current increases.
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Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
沪ICP备16038578号-3
Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
