In 2014, the South Korean government initiated the “Nutria Eradication Project” to actively manage and control populations of nutria, an invasive alien species that threatens national biodiversity. In the present study, we examined domestic nutria habitats in 2014 to 2018 and analyzed spatial shifts in habitat distribution to develop management policies and eradication strategies for the South Korean Ministry of Environment. A total of 27,487 nutria individuals were captured over five years upon the initiation of the eradication project. We found that the number of habitat tracks decreased from 1510 in 19 administrative districts in 2014 to 176 in 14 districts in 2018. We examined the distribution of nutria habitat tracks and found a northwestward shift at an average angle of 313.9° and 46,656.9 m. This distribution shift prompted improvements in control policies focused on nutria capture to suppress rodent movement and shifting distributions. We redefined the spatial scope of our control regions accordingly and established isolated environments in each region to prevent further spread. Additionally, resource management was focused in areas showing habitat expansion. Overall, we observed an estimated 54% decrease in nutria habitat tracks from 2016 to 2017. Our results have since been enacted in government policies and provide a basis for establishing flexible strategies for effectively controlling nutria habitats and populations. In 2017, the South Korean government allocated additional funds for research and for the development of further control strategies working toward the project’s goals.
-The control method of the bidirectional DC/DC converter for instantaneous regenerative current control is described in this paper. The general method to control the DC/DC converter is the output voltage control. However, the regenerative current cannot be controlled to be constant with this control method. To improve the performance of the conventional control method, the DC-link voltage of the inverter is controlled within the tolerance range by the instantaneous boost and buck operations of the bidirectional DC/DC converter. By the proposed control method, the battery current can be controlled to be constant regardless of the motor speed variation. The improved performance of the DC/DC converter controlled by the proposed control method is verified by the experiment and simulation of the system with the inverter and IPMSM(Interior Permanent Magnet Synchronous Motor) which is operated by the reduced practical speed profile.
This study proposes a field weakening control method with interpolation error compensation of the look-up table based permanent-magnet synchronous machine (PMSM) method. The look-up table (LUT) based control method has robust control characteristics compared to other control methods that use linear controllers for current reference generation. However, it is impossible to store all current references under all circumstances for torque commands. General LUT based control methods use two input parameters. In order to mitigate the effect of discretely stored data, two-dimensional interpolation is used to linearly interpolate values between discontinuous data. However, because the current trajectories of PMSMs are generally ellipsoidal, an error occurs between the linearly interpolated and controllable current references. This study proposes a method to compensate for this interpolation error using a feedforward controller for rapid compensation. The improvement using the proposed method is verified by experiment and simulation.
-This paper shows the design and control methods of the bidirectional DC-DC converter to generate the proper DC-link voltage of a PMSM drive. Conventionally, because the controllable power of the PWM based voltage source inverter is limited by its DC-link voltage, the DC-DC converter is used for boosted DC-link voltage if the inverter source cannot generate enough operating voltage for the PMSM drive. In this paper, to obtain more utilization of this DC-DC converter, optimal DC-link voltage control for PMSM drive will be explained. First, the process and current path of the DC-DC converter will be illustrated, and a control method of this converter for variable DC-link voltage will then be explained. Finally, an improvement analysis of the optimal DC-link voltage control method, especially on the deadtime effect, will be explained. The DC-DC converter of the proposed control method is verified by the experiments by comparing with the conventional constant voltage control method.
-In this paper, a battery charging system for Plug-in Hybrid Electric Vehicle (PHEV) and Electric Vehicle (EV), and operation algorithm of charging system are introduced. Also, the proposed charging system uses commercial electricity in order to charge the battery of parked PHEV and 48V battery charging system with power factor controllable single phase converter for PHEV is investigated in this paper. This research verifies the power factor control of input and the converter output controlled by the charge control algorithm through simulation and experiment.
This paper proposes a compensation method for interpolation error of the maximum power control of a PMSM control system that generates current commands through a look-up table. A torque control system using a look-up table created through experiments has superior characteristics, such as control stability and torque accuracy, compared to a system that executes torque control via a linear controller based on modeling. However, it is impossible to generate information on all the currents for the output torque in the table. Therefore, because the data stored in the look-up table have a discrete characteristic, they are linearly interpolated to generate a current command for the torque command. However, the PMSM current trajectory is generally elliptical, which causes an error owing to linear interpolation, reducing the maximum output power. In particular, when the table data are insufficient, such as in the high-speed operation range, the reduced maximum output cannot be ignored. This paper proposes a compensation method for the interpolation error using two feedforward compensators and a PI controller, which was verified through experiments.
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