Toshimasa Haneyoshi

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. >

Deadbeat control of PWM inverter with modified pulse patterns for uninterruptible power supply

A modified algorithm of pulse-width-modulation (PWM) inverter deadbeat control suitable for uninterruptible-power-supply (UPS) systems is presented. Two state variables are measured at each sampling interval, then, using the data, the pulse width is computed in real time in order to force the output voltage equal to the reference at each sampling instant which is called the deadbeat control. Two kinds of PWM pulse patterns are used to increase the fundamental component of the output voltage, considering the microprocessor computation time. Experimentation and simulation has verified that the proposed control scheme increased the output-voltage amplitude, providing an excellent transient response and accurate phase positioning for various load conditions. This algorithm is suitable for applications of high-power UPS systems, in which the switching frequency is in the range of a few kHz and the precise control of power flow is required. >

A predictive instantaneous-current PWM controlled rectifier with AC-side harmonic current reduction

A new single-phase bridge rectifier controlled by a predictive instantaneous-current PWM control scheme for reducing AC-side harmonic currents and improving power factor is proposed. The rectifier can operate at the unity displacement power factor and has fast response to an input signal as a current reference. The effect of the DC-side voltage ripples is taken into account. The paper describes three digital control schemes for such rectifiers and presents experimental and simulation studies on steady-state and dynamic performances of the rectifier. The effectiveness of the control schemes is confirmed by experiments and simulations. The proposed rectifier can be used for applications such as UPS systems and static VAr compensators.

Development of externally powered lower limb orthosis with bilateral-servo actuator

The externally powered orthosis is one of the necessary devices for rehabilitation of paraplegia patients and hemiplegia patients and spinal-cord-injury victims. However, the main problems of speed, noise, and weight and so on make the morale of the training lower. Then, we thought that there were problems in the actuator. To overcome these problems, we have developed the orthosis externally powered by bi-articular muscle mechanism with a bilateral-servo actuator. Our study suggests such a system as the physically disabled can train with the externally powered orthosis and ambulation device in smooth action.

A new method for digital PLL control using estimated quadrature two phase frequency detection

In the electric power utility system, PLL control is used to synchronize the inverter voltage to the interconnection voltage. Generally for the single phase system, the PLL control system is constructed with the zero crossing point detection method. In this paper, an estimated quadrature two phase frequency detection method based on the digital controller is proposed which detects the phase and frequency of the utility faster than the zero crossing point detection method. The proposed method is verified by simulation and experiment. In the proposed method, a quadrature two phase signal is estimated from the interconnection waveform. In the simulation, steady-state characteristics and influences of disturbance and harmonics are discussed. In the experiments, the actual performance of the proposed method is investigated.

Deadbeat controlled PWM inverter with parameter estimation using only voltage sensor

A new control technique based on deadbeat control theory is proposed to obtain a nearly sinusoidal PWM inverter output voltage using only a voltage sensor. The closed-loop sampled-data feedback scheme inherently results in very fast response to load disturbance and nonlinear load, producing low total harmonic distortion. Parameter estimation of the plant provides a type of self-tuning of the proposed controller. A theoretical analysis and simulation and experimental re- sults are presented for a single-phase PWM inverter controlled by an Intel 8086 microprocessor.

Predictive instantaneous value controlled PWM inverter for UPS

A microprocessor-based pulse-width modulation (PWM) inverter (UPS) that obtains high-quality sinusoidal output voltage even under a rectifier load is proposed for uninterruptible power supplies. The proposed PWM inverter system uses a closed-loop digital feedback with a sinusoidal reference, and the PWM pattern is determined at every sampling instant. A modification that increases the maximum pulse width, which is limited by the computation time in conventional digital approaches, to provide larger output voltage and a repetitive control technique are applied to the proposed control system. A larger maximum pulse width, stable operation, high output voltage accuracy, very low output voltage distortion, and very fast response are realized.<<ETX>>

High power factor PWM rectifiers with an analog pulsewidth prediction controller

A single-phase PWM bridge rectifier controlled by a pulsewidth prediction (PWP) method to operate switching devices to realize a high power factor and to reduce the AC-side current harmonics is proposed. The PWP controller provides instantaneous current control with either a constant frequency carrier or a piecewisely fixed multiple-frequency carrier in one source-voltage cycle. The paper describes the control methods and implementation of analog PWP controllers, and performance characteristics of the rectifier. Unity displacement power factor was obtained and the AC-side current harmonics were reduced. Experimental results show the usefulness of the proposed method and applicability to rectifiers in UPS systems, etc.

The rigidity of the bi-articular robotic arm with a planetary gear

This paper describes the motor drive system which is applied a planetary to the power distribution mechanism. This motor drive system can realize the function of Bi-articular muscles peculiar to an animal. The relation between the motor drive and force is considered. The rigidity of the arm tip with bi-articlar muscles is shown.

A study of instantaneous value control with voltage variation compensation for UPS inverters

A new approach for real time digital feedback control of PWM inverter is proposed, in which an instantaneous value control with voltage variation compensation is achieved. In this scheme, the sampling frequency of the inverter becomes half of the carrier frequency, and it is suitable to implement for higher carrier frequency. In this paper, the output characteristics of the inverter for various LC filter components are evaluated. Also the influence of the capacitor current feedback signal for the output characteristics are verified. From the view point of UPS applications, the advantages and disadvantages are discussed though simulations and experiments, the superiority of the proposed control law is verified.