Atsuo Kawamura

Dead Beat Microprocessor Control of PWM Inverter for Sinusoidal Output Waveform Synthesis

A new control technique based on dead beat control theory to obtain a nearly sinusoidal PWM inverter output voltage is described. The closed loop digital feedback system measures the output and controls the inverter switches to generate the required PWM pattern to produce low total harmonic distortion (THD) sinusoidal output voltage. This scheme inherently provides very good voltage regulation, phase positioning and compensation for load disturbances and nonlinear loads. This paper presents a theoretical analysis, computer simulation and experimental results for a single-phase bridge inverter controlled by an Intel 8086 microprocessor based system.

Waveform compensation of PWM inverter with cyclic fluctuating loads

A repetitive voltage compensation technique that generates a high-quality sinusoidal output voltage from a single-phase pulse width modulation (PWM) inverter used for uninterruptible power supplies is described. A repetitive control technique eliminates the steady-state error in the distorted output voltage caused by cyclic loads. The proposed PWM inverter system uses microprocessor-based closed-loop digital feedback with a sinusoidal reference. The PWM pattern is determined at every sampling instant by the proposed algorithm, implemented by a microprocessor using a set of detected output voltages and the reference signals through one cycle. The system has low distortion and very fast response for AC phase-controlled loads. >

Perfect tracking control based on multirate feedforward control with generalized sampling periods

In this paper, a novel perfect tracking control method based on multirate feedforward control is proposed. The advantages of the proposed method are that: (1) the proposed multirate feedforward controller eliminates the notorious unstable zero problem in designing the discrete-time inverse system; (2) the states of the plant match the desired trajectories at every sampling point of reference input; and (3) the proposed controller is completely independent of the feedback characteristics. Thus, highly robust performance is assured by the robust feedback controller. Moreover, by generalizing the relationship between the sampling period of plant output and the control period of plant input, the proposed method can be applied to various systems with hardware restrictions of these periods, which leads to higher performance. Next, it is shown that the structure of the proposed perfect tracking controller is very simple and clear. Illustrative examples of position control using a DC servomotor are presented, and simulations and experiments demonstrate the advantages of this approach.

Wireless transmission of power and information and information for cableless linear motor drive

In previous papers, the authors introduced the wireless transmission of power and information (WTPI) for realizing a future manufacturing system which is free from the complexity of wiring for the power supply or control. In extension from these studies, the authors have attempted to apply the linear-type WTPI for realizing the maintenance-free drive and the multimover operation of a moving coil-type linear motor. This paper describes the basic concept of the WTPI and the analysis on the performance of the WTPI configured in the linear shape, thereafter introducing the preliminary test result on a prototype of the cableless linear pulse motor (CLLPM) which was constructed by integrating a linear pulse motor (LPM) with the associated driver and the linear WTPI for noncontact motion transfer.

Wireless transmission of power and information through one high-frequency resonant AC link inverter for robot manipulator applications

A contactless decentralized power supply is proposed with communication capability through only one transformer. A prototype of a wireless transmission system of power and information (WTPI system) was built, and the two-axis position controls of servo motors were achieved by transferring the power and signal through one rotatable high-frequency transformer. The proposed concept can be applied for robotics and numerical control (NC) machines.

Simulation of an autonomous biped walking robot including environmental force interaction

This autonomous biped walking control system is based on reactive force interaction at the foothold. The precise 3D dynamic simulation presented includes: 1) a posture controller which accommodates the physical constraints of the reactive force/torque on the foot with quadratic programming; 2) a real-time COM (center of mass) tracking controller for foot placement, with a discrete inverted pendulum model; and 3) a 3D dynamic simulation scheme with precise contact with the environment. The proposed approach realizes robust biped locomotion because environmental interaction is directly controlled. The proposed method is applied to a 20 axes simulation model, and stable biped locomotion with velocity of 0.25 m/sec and a stepping time of 0.5 sec/step is realized.

Instantaneous Feedback Controlled PWM Inverter with Adaptive Hysteresis

A new control strategy for a PWM inverter controlled through adaptive hysteresis in an instantaneous feedback loop is theoretically analyzed and verified through simulations and a low-power experimental circuit. This control gives excellent performance under various load conditions, and it is especially effective in reducing load injected harmonics.

Practical study on wireless transmission of power and information for autonomous decentralized manufacturing system

In previous papers, the authors have already introduced the idea of an autonomous decentralized manufacturing system (ADMS), in which machines receive electrical energy through wireless power transmission and also are decentrally controlled through wireless transmission of the control and feedback data. With this idea, the degree of freedom in motion control is enlarged, and the system has the capability of adaptive reconfiguration to product variation as a result. In this paper, the practical problems for realization of wireless transmission of power and information (WTPI) needed for the proposed ADMS are clarified, and the practical solutions to these problems are presented. Several industrial applications of the WTPI are also introduced.

Integral motor with driver and wireless transmission of power and information for autonomous subspindle drive

This paper describes the novel technology of an integral motor with the associated driver and wireless transmission of power and information (WTPI), which is effectively applied to autonomous spindle drive for the sophisticated workpiece machining. The power supply to the integral motor is made by way of a separable WTPI coupling. In addition, calculation for variable voltage and variable frequency (VVVF) control is done at the primary side of the coupling, and then the frequency command is transmitted to the secondary side by an overlapped transmission of the data on the power transmission through the WTPI coupling. At the secondary side, direct power conversion from the induced high-frequency voltage to the motor terminal voltage is conducted using a bidirectionally controllable power switch. The amplitude of the terminal voltage is adjusted by changing the inverter voltage at the primary side. In this way, the VVVF drive is made through the WTPI coupling, thus providing the integral subspindle with the autonomy for sophisticated machining.

Disturbance observer based fully digital controlled PWM inverter for CVCF operation

A new approach for digital feedback control of a PWM inverter is proposed, in which an output DB (deadbeat) control is achieved combined with a disturbance observer. In the proposed scheme, the pole placements of the state observer and the disturbance observer are chosen separately. When the two observers employed the same pole placements, the experimental setup had a tendency to become unstable due to the detection error. By selection of the different pole placements, the disturbance observer quickly estimates the disturbance and feedforward disturbance cancellation is achieved. Then the state observer estimates the state variables at the next sampling instant, and the deadbeat controller is applied to the nominal system. This scheme has advantages in robustness in the practical application. From the view point of UPS applications, the advantages and disadvantages are discussed through simulations and experiments. Compared with other digital control laws, the superiority of the proposed control law is verified. >