Yasuhiko Neba

Model for a Three-Phase Contactless Power Transfer System

This paper studies the model for the three-phase contactless power transfer system. A phase winding in the three-phase contactless power transformer has the magnetic couplings with all of the other phase windings. Moreover, the magnetic couplings depend on the displacement of the secondary armature with respect to the primary armature. The equivalent model of the three-phase system with the complicated mutual inductances due to such magnetic couplings is presented. The model is transformed into the single-phase model that is similar to the model for the conventional system. The simplified model allows the easy consideration of the operation of the three-phase system. By using the model, the resonant capacitances for the three-phase system are available. The model is confirmed to successfully simulate the performance of the actual system. In addition, the experimental and theoretical results confirm that the three-phase system has the stable performance of the power transfer independently of the displacement of the secondary.

New GTO Current Source Inverter with Pulsewidth Modulation Control Techniques

A new GTO current source inverter in which two auxiliary GTOs are added to the basic inverter circuit, which consists of six GTOs and three capacitors, is presented. One of the auxiliary GTOs is connected between the positive line of the inverter and the neutral of three Y-connected capacitors; another is connected between the negative line and the neutral. In the proposed inverter, the charges of three capacitors are controlled at the same time by means of pulsewidth modulation (PWM) to main GTOs and auxiliary GTOs. This inverter can supply both the sinusoidal current and voltage to the motor. The PWM control technique, the operating principle, and the experimental results for 2.2-kW induction motor drives are described. The output current waveform of this inverter is closely sinusoidal, as opposed to trapezoidal in the basic inverter circuit. The steady-state characteristics of the GTO-CSI induction motor drive system are analyzed by the state-variable methods, and a close agreement between the analyzed and the experimental results is obtained. Smooth and noiseless drive of induction motor over a wide range of speed is observed.

A PWM GTO current source converter-inverter system with sinusoidal inputs and outputs

A current-source-type GTO converter-inverter system with pulsewidth modulation (PWM) techniques is presented. The inverter circuit consists of six main GTOs, two auxiliary GTOs, and three shunt-filter capacitors, and the converter circuit has the same arrangement as the inverter. The system realizes sinusoidal input and output voltage/current by a simple PWM strategy. Two auxiliary GTOs contribute to shaping the inverter output current into the sinusoidal wave, controlling the DC link voltage, and shaping the converter input current into the sinusoidal wave. The PWM pattern in the inverter, the PWM methods, and the DC link voltage control for the converter are explained in detail. The experimental waveforms of the input and output voltage/current are shown when a 2.2 kW induction motor is driven. The input and output characteristics in the DC link voltage control of the converter are given. >

A simple method for suppression of resonance oscillation in PWM current source converter

This paper deals with a suppression method for the resonance oscillation in the ac side of a pulse-width modulation (PWM) current source converter. The converter is operated with the PWM switching pattern which is generated by the full digital control of computer software. The resonance current, caused by the LC low pass filter at the step change of the pattern, can be effectively suppressed by one pulse control of the pattern. The proposed method does not need to have the feedback loop of the current/voltage and does not offer the switching stress of the devices. The switching timing of the control is determined by pre-calculation of the off-line in consideration of the circuit constants. The experimental and the simulated results in the single-phase and the three-phase PWM converters are given, compared with those without the control, and show good response of the supply current.

Analysis of PWM GTO Current Source Inverter-Fed Induction Motor Drive System

A GTO current source inverter which consists of six main GTOs, two auxiliary GTOs, and three capacitors is presented. This inverter can supply both the sinusoidal voltage and current to the motor by pulsewidth modulation (PWM) techniques. The normal PWM pattern produced by two control signals with the carrier and the modulating waves and the optimal PWM pattern determined by the harmonic analysis are described. The experimental waveforms for 2.2-kW induction motor drives are given and the circuit operation of this inverter in the PWM technique is clearly shown. In addition, the steady-state characteristics of this inverter-induction motor drive system are analyzed by the state-variable methods, and a close agreement between the analyzed and the experimental waveforms is obtained. It is shown that the harmonic components are eliminated or reduced by using the optimal PWM pattern, and the new inverter with sinusoidal current and voltage is very excellent for ac motor drive.

Comparison of Characteristics on Planar Contactless Power Transfer Systems

This paper reports the characteristics of planar contactless power transfer systems, which are classified into the following types: single-phase primary and single-phase secondary system (SS system), three-phase primary and single-phase secondary system (TS system), and three-phase primary and three-phase secondary system (TT system). The SS system is used in conventional contactless power transfer. On the other hand, in the last few years, the TS system has been studied more. As a novel system, the TT system is here proposed. The characteristics of all three systems are measured by using a common experimental prototype made of printed circuit board. The comparison confirms that the TT system has higher efficiency and can output uniform power independent of the secondary position, as compared to the other systems.

Quick regulation of sinusoidal output current in PWM converter-inverter system

An induction motor drive system composed of a current-output-type converter and a current-source inverter with sinusoidal input and output voltage/current is presented. Pulse-width modulation (PWM) strategies with gate turnoffs were applied to the converter and the inverter sections in order to reduce the current harmonics and suppress the motor torque pulsation. A method for quick regulation of the AC output current amplitude that was applied to the PWM inverter section is presented. To demonstrate the improvement in the current response of the inverter, the slip frequency/current regulation of an induction motor is considered. The experimental results obtained for steady-state and dynamic operations of the motor are shown. The merits and demerits of this control method are discussed.<<ETX>>

A PWM current source type converter-inverter system for bidirectional power flow

The experimental results for indication machine drives and the bidirectional power conversion using a pulsewidth-modulated GTO (gate-turn-off) type converter-inverter system are presented. The system has sinusoidal voltage and current at both the input and the output terminals. The PWM method is explained in detail, and the harmonic components contained in the PWM pattern are analyzed. The AC output current regulation by the PWM inverter with constant DC current is also discussed. The voltage and the current waveforms when this system is applied for the power conversion between 60 Hz and 50 Hz power sources are given. The experiment shows that this system can be used for various purposes.<<ETX>>

Trifoliate Three-Phase Contactless Power Transformer in Case of Winding-Alignment

This paper proposes a trifoliate three-phase contactless power transformer. This transformer can achieve balanced electrical behavior between three phases at winding alignment. For this transformer, models are presented with accompanying detailed explanations. The models reproduce the electrical behavior more precisely than conventional models. A contactless power transfer system using a prototype of the proposed transformer and the resonant capacitances estimated by the models works effectively and attains good performance levels. In addition, in winding misalignments with slight displacements, the system is able to maintain these high-performance levels.

Current regulated PWM-CSI induction motor drive system without a speed sensor

A current source inverter (CSI)-induction motor drive system without a speed sensor is considered. An input DC link current which is kept constant by a pulse-width-modulated converter with sinusoidal input current is supplied in the PWM inverter. The inverter output current with sinusoidal wave is directly regulated by employing the modulation index control of the PWM strategy. Experiments show that high-performance steady-state behavior and acceleration/deceleration characteristics with smooth drives and low noise of the motor have been obtained. It is demonstrated that the system with only the current sensor has the same steady-state and transient characteristics as the system with the voltage and the current sensors.<<ETX>>