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-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.

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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.

This paper proposes a space vector modulation (SVM)-based common-mode (CM) currents reduction method of an H8 inverter for permanent magnet synchronous motor (PMSM) drives. There are power quality issues in the PMSM drive systems, such as current distortions and CM electromagnetic interference (EMI) due to the fast-switching operation of the inverter. These issues are related to CM voltage (CMV) and CM current (CMC). Although several studies have been conducted to reduce the CMV and CMC, some CMV variations and CMCs are still generated in the real implementation. Unlike conventional methods, the proposed method selects the voltage vectors with similar CMV levels and arranges them considering the series-connected switch operation of the H8 inverter in a voltage vector modulation sequence. At a low modulation index (MI), the proposed method completely restricts the CMV variations into six times. At high MI, the proposed method synthesizes the reference voltage vector differently, depending on the position of the reference vector, to reduce both current distortions and CMCs. The validity of the proposed method is verified through simulations and experimental results.

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