This paper presents an improved voltage flux-weakening strategy of a permanent magnet synchronous motor (PMSM) in a high-speed operation. The speed control performance using voltage flux-weakening control is not affected by the motor parameters, so it is used in various motors for high-speed operations. In general, the voltage flux-weakening control uses voltage references to generate a flux axis current reference. However, there may be errors between the voltage reference and the actual voltage flowing into the motor. This causes an error in the current reference generation and reduces the efficiency of the inverter and motor due to the use of more current. In this paper, the problems that can occur due to voltage errors were analyzed through theoretical approaches and simulations, and improved voltage flux-weakening control to resolve these problems was presented. This method’s advantage is that the error between the voltage reference and the voltage applied to the motor can be minimized, and the target speed can be reached with minimum current. As a result, it was possible to increase the energy efficiency by reducing the amount of current flowing through the motor. The effect of the improved voltage-based flux-weakening control method was verified through simulations and experiments. As a result, the voltage errors were reduced by approximately 2.16% compared to the general method. Moreover, the current used in the field-weakening control region was reduced by up to 27.17% under the same torque condition.
This study presents a method for monitoring the voltage across the AC capacitor in a gridconnected hybrid active power filter without the use of additional voltage sensors. In the case of an AC capacitor used in a hybrid, active power filter, there is a risk of burnout caused by exceeding the allowable voltage owing to the harmonic current and voltage generated by the inverter. Therefore, this study presents a method to monitor the voltage of the AC capacitor using the current from which the DC component has been removed without any additional voltage sensors to prevent the burn-out of the AC capacitor. The proposed sensorless AC capacitor voltage monitoring method is verified through simulations and experiments. The difference between the magnitude of the voltage measured in the simulations and experiments and the magnitude of the voltage predicted with the proposed method was approximately 0.526[%] on average.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.