This paper proposes a mode switching bilateral control for the extension of motion areas. Conventionally, a bilateral control with a dynamical matrix has been used to achieve haptic transmission with different motion ranges between the master and slave systems. However, this approach still does not allow operators to enhance operability, especially when the slave system is in contact with environment. Taking the contact motion in the bilateral control into consideration, a basic bilateral control with an Hadamard matrix for the same motion areas is suitable for immediate and fine haptic transmission. To solve the contact motion problem, the proposed control structure switches the dynamical and the Hadamard matrices between free and contact motion. The characteristic of the proposed method is that the structure of the disturbance observer is applied to the modal space in order to solve the initial-value problem. With this method, smooth switching of the modal transformation matrix is achieved in both soft and hard environments. As a result, the operability of the different motion areas will be enhanced.
This paper discusses a damping control that is applied to multi-modular matrix converters in order to suppress the oscillation due to the LC resonance of the input filter. The multi-modular matrix converter connects a multiple winding transformer and several modules. The module consists of a three-phase to single-phase matrix converter and filter capacitors. It is found that the multi-modular matrix converter has a resonance problem between the leakage inductance of the transformer and the filter capacitors in the modules. In this paper, a damping control combined with the output current control of the multi-modular matrix converter is proposed to suppress the resonance and to achieve better input current quality. The proposed damping control can divert the output current sensors for an ACR (auto current regulator), which is generally used in the adjustable speed drive system of a motor. Therefore, the proposed damping control does not require additional sensors, which is an advantage over the conventional damping control applied to the input stage of the multi-modular matrix converter. From the experimental results, the proposed damping control improves the input current THD (total harmonic distortion) by 75.5%. In addition, the proposed damping control obtains a higher damping performance than the conventional damping control.
The multi-phase method is effective in downsizing the power converter system. Because of the multi-phase boost chopper circuit, the output capacitor and the cooling system can be downsized in the case of the boost chopper circuit. Furthermore, the volume of the inductor can be reduced using the transformer-linked method. However, there is little comparative data available on the output capacitor in the boost chopper of the conventional multi-phase method and the transformer-linked method. The purpose of my work was to examine the characteristics of the output capacitor in both the multi-phase method and the transformer-linked method. To evaluate the performance of the downsized capacitor, a voltage ripple analysis has been successfully employed as the index of the volume of the output capacitor. From the experimental results, it was found that there is little difference between the multi-phase method and the transformer-linked method in regard to the voltage ripple of the output capacitor. The experimental results indicate that the performance of the downsized capacitor is the same for the multi-phase method and the transformer-linked method.