A mapping system for electric power distribution system draws the facility symbol of an electric power supply on the topographical map, and also writes a character string of facility name close to the corresponding facility. However, in the concentrated area of the facilities, it is difficult to place character string without overlapping with other figures. Therefore we will propose a method of placing character string close to the facility symbol automatically for the mapping system of electric power distribution system. Also we will propose a method of drawing comment line automatically when the character string were placed far from the corresponding facility. Our testing showed more than 99% of success rate for the method of placing character string, and also more than 93% of success rate for the method of drawing comment line. The processing time for both methods were fast enough to be used in the practical use. This paper will define the problem of mapping system for the electric power distribution system and will discuss about the solution of solving the problem. Furthermore, we will introduce the testing result which were done by using the real mapping system data, and show the validity of these methods.
In recent years, along with the increase of the power converter used in home information equipments and home electric appliances, the harmonic current in the single-phase utility line generated from the converter causes a problem to electronic equipments. An active filter is one of the effective solutions for this problem. But the conventional type active filters utilize voltage source PWM inverter, which requires high switching frequency in order to compensate high order harmonic current in general. Using high switching frequency, this type inverter generates the electromagnetic noise and gives interference to other electronic equipments. So we propose the new type active filter using linear power amplifier with no switching operation. We have already reported that this type of active filter is useful for suppressing the higher harmonic current effectively. However the efficiency of this type active filter is very low. So we study on the reduction of the capacity of linear power amplifier by using combined type active filter in this paper. By combining the active filter that used linear power amplifier, and a partial-switching type active filter operating at low switching frequency, we show by theoretical and experimental results that the proposed active filter is effect to suppress the higher harmonic current in a single-phase utility line.
In recent years, parallel-operation of inverters is employed to increase reliability and capacity in an uninterruptible power supply (UPS) system. A phase error in PWM carrier-signals of each inverter causes high frequency loop current between inverters. Therefore, the PWM carrier-signal of each inverter should be adjusted in phase. This paper proposes a detection method of phase error in PWM carrier-signal and its application to synchronization control for parallel-connected inverters. A simple definite-integral circuit achieves the detection of carrier phase error from high frequency loop current using no signal line between inverters. The detected carrier phase error is applied to synchronize the PWM carrier-signal through a PI-compensator, and then the high frequency loop current can be suppressed. Several experimental test-results show the validity of the proposed detection method and synchronization control.
This paper proposes a novel control method based on the virtual AC/DC/AC conversion for the matrix converter. The virtual AC/DC/AC conversion method is a very simple strategy to control the input current and the output voltage for the matrix converter. There are two new topics proposed in this paper. Firstly, this paper proposes the minimum switching loss modulation on the virtual rectifier. In case of the proposed modulation, only two arms switching in the virtual rectifier using dc link current control by the virtual inverter can obtain clean sinusoidal input current. Secondly, a novel lean controlled carrier modulation on the virtual inverter is proposed. The leans of the triangle carrier are controlled by the duty ratio of the rectifier side pulse. The lean controlled carrier reduces harmonic distortion of the input current by avoiding interference between the rectifier control and the inverter control. These new proposals are confirmed by simulation and experimental results.
This paper deals with the high-frequency equivalent circuits of permanent magnet synchronous motor (PMSM) driven by a PWM inverter. The leakage current (common-mode current) flows through stray capacitance among stator windings and iron core (frame) of an synchronous motor at the switching instants of inverter transistors. A high-frequency equivalent circuits of PMSM are derived based on the frequency characteristics of the high-frequency zero-phase-impedance and line-to-line-impedance of synchronous motor. The validity of the proposed equivalent circuit is confirmed by simulation considering parasitic capacitance of the inverter.
In high performance active vibration control for a flexible structure, it is requirement to establish an accurate model identified not only 1st but also 2nd and 3rd vibration modes of the flexible structure. This paper presents the derivation method of a modal model of flexible structures based on the advanced system identification theory. In this identification, multi-decimation (MD) operation is applied to identify wide frequency region in a short vibration time accurately. By using circle curve fitting on each identified mode, one modal model can be derived from MD identified models. We apply the proposed identification method to the three-story structure, and we show the effectiveness of the proposed method through both the identification and the vibration control experiments.
This paper proposes a new inverter drive system for an interior permanent magnet (IPM) synchronous motor and an inverter control strategy to obtain the unity power factor operation of the single-phase diode rectifier. The motor drive system for home appliances requires improving the input power factor without a reactor, an electrolytic capacitor and a switching device. This paper can achieve to improve the input power factor without a reactor, a current control-switching converter and an electrolytic capacitor. The proposed system consists of only single-phase diode rectifier, small film capacitor (10uF/kW) across the dc-bus, three-phase inverter and IPM motor. Source side energy provides directly to the motor without smoothing the dc-bus voltage. There are many ripple voltages across the dc-bus. A principle of unity-power-factor operation is that the inverter makes the waveform of input current sinusoidal. The unity power factor operation is achieved by dither effect. For IPM motor, the inverter control scheme in this paper is based on direct torque control (DTC). The proposed system is constructed by the input current controller based on DTC. The additional current controller improves its input current waveform. This paper describes that the proposed method achieves the power factor 98.8% by experimental tests.
Recently, the sinusoidal drive of a permanent magnet synchronous motor has been actively researched because of its low noise and low vibration. Moreover, the sinusoidal drive system which uses only a low-resolution position sensor without utilizing the current sensor is researched. This paper proposes the method for deciding the lead angle of the impressed voltage by an easy expression for current sensor-less sinusoidal drive system of a permanent magnet synchronous motor with a low-resolution position sensor. The method is a technique for indirectly controlling the current phase without the dq axis transformation. First, the control method of adjusting the current of d axis to almost 0 and the control method of the weakening magnetic flux were shown. And, the methods were examined in numerical analyses. Next, the effectiveness of the proposed phase control method was verified using an actual motor. In the control method of adjusting the d-axis current to almost 0, the locus of the current vector was confirmed and an excellent transient response for controlling the current of d axis was obtained. Moreover, it was confirmed that the increase of applied voltage was controlled and the range of the drive had expanded in the method of the flux-weakening control.
This paper deals with a hybrid shunt active filter for harmonic compensation of a three-phase diode rectifier in a 480-V adjustable-speed motor drive system. The hybrid filter is formed by a three-phase LC filter tuned around the 7-th harmonic frequency and a small-rated three-phase voltage-source PWM inverter. The LC filter and PWM inverter are directly connected in series. As a result, the dc capacitor voltage of the PWM inverter in the hybrid filter is much lower than that of a conventional pure shunt active filter. This results in higher efficiency, less switching ripple and less EMI emission. Computer simulation is carried out to compare the hybrid filter with the pure filter in terms of circuit configuration and filtering performance. Simulation results indicate that the hybrid filter is superior in effectiveness and viability to the pure filter. In addition, theoretical analysis based on vector loci confirms the validity of the simulation results.
In this paper, a 3-phase series-connected hybrid converter system is introduced. The converter system is constructed by a GTO converter and an IGBT converter connected in series by two output transformers aiming at a high voltage high efficiency converter. The GTO converter operates in a square-wave switching mode at the same switching rate as a reference output voltage in order to minimize the device switching losses. The IGBT converter is built in an NPC (neutral-point-clamped) arrangement and operates in a PWM switching mode at a high switching rate. The former produces a base part of the total output voltage. The latter not only produces an additional part of the total output, but also offsets the harmonic components generated by the GTO converter. The control strategy for the system is proposed, and the experiment on an inverter, rectifier and STATCOM operation is demonstrated using the proposed hybrid converter. The experimental results verified the validity of the proposed hybrid configuration and its control strategy.
This paper proposes a new control method of matrix converter to obtain the unity power factor operation. Source side of the matrix converter is single-phase voltage, and the load side is three-phase ac motor. The number of switching device is six, and the converter does not require a reactor or an electrolytic capacitor. Generally, it is difficult for matrix converter to control both its input current waveform and the output voltage waveform, because the switching devices are connected to both source side and load side. In this paper, applying an algebraic transfer matrix, the control method of single-phase to three-phase matrix converter applies the indirect modulation model. The indirect modulation model treats a matrix converter as a two-stage transformation converter. The rectifier of proposed model consists only diode and small L-C filter. Hence, the switching frequency is lower than the conventional model one. The inverter of the proposed model regulates both the input current waveform and the motor speed. The inverter control scheme for IPM motor is based on direct torque control (DTC). The additional current controller improves its input current waveform. Hence, an optimum switching pattern of the matrix converter realizes quick torque response and unity power factor operation. This paper describes that the proposed method achieves the power factor 97.6% by experimental tests. The experimental results confirm the feasibility of the proposed method for matrix converter.
This paper deals with a maximum power point tracking (MPPT) control of the photovoltaic generation with the single-phase utility interactive inverter. The photovoltaic arrays are connected by employing the PWM current source inverter to the utility. The use of the pulsating dc current and voltage allows the maximum power point to be searched. The inverter can regulate the array voltage and keep the arrays to the maximum power. This paper gives the control method and the experimental results.
The authors suggest a new technique for damping of natural oscillation in full-step drive of a stepping motor. In this technique, the torque equilibrium position is produced at any point and moved smoothly by adjustment of the order and the intervals of the pulse train command, without modification in the hardware. The advantage of this method is confirmed by the experiment.
The single-phase buck rectifier has several advantages, such as the controllability of lower dc output voltages, and negligible inrush input-current at start-up. However, the rectifier requires an LC-filter connected on the input side of the switching device to absorb the harmonics caused by the on and off behavior. The LC-filter involves an LC resonance in transient states. To solve this problem, a suppression approach using only a series RLC circuit, which selectively acts as a damping at around the resonant frequency, is proposed. Simulation and experimental results confirm the validity of this method.
This paper presents a novel circuit topology to attain soft switching operation of a high frequency inverter. Its output power is regulated over a wide range using a PWM control technique by connecting an auxiliary resonant circuit to the conventional single ended push pull (SEPP) high frequency inverter for induction heating. All switching devices in the proposed inverter are operated soft switching mode. This paper describes its circuit constitution and obtained experimental results from a practical point of view.