摘要:
It is an object of the invention to provide a magnetic sensor and a current sensor that exhibit high performance at low costs. A magnetic sensor has a magnetic core (1) having a magnetic saturation property and a sensor coil (2) wound around the magnetic core (1). An end of a detection coil (20) is connected to an end of the sensor coil (2). The other end of the detection coil (20) is grounded. The magnetic sensor further comprises a drive circuit (3) and a detection circuit (4). The drive circuit (3) has a series resonance circuit part of which is made up of the sensor coil (2). To the sensor coil (2) the drive circuit (3) supplies a resonance current flowing into the series resonance circuit as an alternating current that allows the magnetic core (1) to reach a saturation region. The detection circuit (4) detects a magnetic field to be measured by detecting variations in resonance current flowing through the sensor coil (2).
摘要:
A magnetic sensor apparatus comprises a magnetic detector (101) that outputs a signal responsive to a magnetic field and a magnetic substance (110) having a cavity (111) in which the magnetic detector (101) is placed. The magnetic detector (101) is placed in the cavity (111) of the magnetic substance (110). The ratio between a magnetic field (H) to be measured and a magnetic field applied to the magnetic detector (101) is set to a specific value, based on at least one of a first demagnetizing factor depending on the shape of the magnetic substance (110) and a second demagnetizing factor depending on the shape of the cavity (111). The magnetic sensor apparatus further comprises a feedback coil (112) that applies a negative feedback magnetic field to the magnetic detector (101) and a reference magnetic field coil (113) that applies a reference alternating magnetic filed to the magnetic detector (101) for controlling the property of the magnetic detector (101).
摘要:
This PWM inverter apparatus includes a first and second current control type semiconductor switching elements connected in series which are connected in parallel to a DC power supply. An output is generated by alternately switching the first and second semiconductor switching elements. Resistive semiconductor switching elements having a higher switching speed than the first and second semiconductor switching elements and a resistance-to-current characteristics producing a voltage drop are respectively connected in parallel to respective the first and second semiconductor switching elements. In a half cycle of an alternating output current, while the output current is higher than a predetermined rate with respect to a peak current, a switching timing is controlled to produce a switching control signal to the resistive semiconductor switching elements ahead of a switching control signal to the first and second semiconductor switching elements, and to terminate the switching control signal to the resistive semiconductor switching elements at a time when a predetermined period passes after the switching control signal given to the first and second semiconductor switching elements has been terminated. In the half cycle of the alternating output current, while the output current is lower than the predetermined rate with respect to the peak current, the switching timing is controlled to generate the output by the switching operation only of the resistive semiconductor switching elements.
摘要:
The present invention discloses a power conversion apparatus comprising a control circuit for generating a switching signal at the timing allowing soft-switching to be achieved, and free from any occurrence of ripple. The power conversion apparatus includes a first main switch (Q1) and a second main switch (Q2) which are connected in series with each other. One of the ends of the first main switch is connected with the positive side of a DC power supply, and one of the ends of the second main switch is connected to the negative side of the DC power supply. A diode (D1, D2) is connected in parallel with each of the main switches so as to become reverse biased with respect to the DC power supply. A main-switch snubber capacitor (C1, C2) is connected in parallel with each of the main switches. A load is connected with the junction between the pair of main switches, and the main switches are controllably switched according a switching signal from a control circuit to generate an output. A first auxiliary resonant circuit including serial-connected first and second auxiliary switches (Q3, Q4, Q5, Q6) and a resonant inductor (L1) connected in series with the second auxiliary switch is connected with each of the positive side of the DC power supply and the junction between the two main switches. A diode is connected to each of the first and second auxiliary switches so as to become reverse biased with respect to the DC power supply. The control circuit provides a turn-on signal to the first and second auxiliary switches according to a voltage signal as an input representing the voltage across each of the main switches and auxiliary switches from voltage detecting means before a turn-on signal as the switching signal is provided to the first main switch.
摘要:
In a power conversion apparatus using a semiconductor switching element, a collector-emitter voltage detecting device is provided to detect the collector-emitter voltage in the semiconductor switching element in the power conversion apparatus in order to comprehensively reduce switching loss and conduction loss arising in a switching element. A base current supplied to the switching element is controlled based on the detected collector-emitter voltage so as to control the collector-emitter voltage or control a regenerative power to be transmitted from a switching element driving power supply to an external auxiliary power supply or the like. This provides an optimum driving in consideration of factors including dispersion in a specific current amplification factor (hfe) of the switching element, variance in the hfe caused by temperature, and variance in the hfe to a current flowing through the switching element, for reducing a sum of conduction loss and driving power of the switching element.
摘要:
A switching circuit for a power conversion apparatus capable of reducing conduction loss to provide a higher efficiency, and achieving downsizing and weight-reduction and higher driving frequency based on the improved efficiency is disclosed. A driving transistor is connected to a switching main transistor to supply a driving power for ON-OFF driving thereto, and an auxiliary power source composed of a current transformer is provided between the main transistor and the driving transistor. An auxiliary transistor having a lower switching loss than that of the main transistor is connected in parallel with the main transistor to form a main switch in combination with the main transistor. A current-driven type transistor serves as the main transistor, and voltage-driven type transistors serve as both of the driving transistor and the auxiliary transistor. The auxiliary transistor is adapted to be driven at a higher speed than that of the main transistor when the main transistor is turned on, and adapted to be driven at a lower speed than that of the main transistor when the main transistor is turned off.
摘要:
A power conversion apparatus capable of reducing the conduction loss to achieve high efficiency yielding a downsized and weight-reduced apparatus and a method for driving such a power conversion apparatus is disclosed. A power conversion apparatus comprising a switching-element driving circuit which includes a current transformer having a primary coil connected to an current control type switching element, and a driving-current generating circuit formed of a secondary coil of the current transformer and a rectifying circuit connected to the secondary coil, wherein an output current generated in the driving-current generating circuit is supplied to the switching element as a driving current of the switching element, and a method for driving the switching element of such a power conversion apparatus are disclosed. This method comprises the steps of detecting an output current of the switching element, and extracting a part of the output current of the driving-current generating circuit out of the switching-element driving circuit so as to variably controlling the driving current of the switching element in response to the output current of the switching element. Preferably, the output current of the driving-current generating circuit extracted out of the switching-element driving circuit is supplied to any other auxiliary power supply as a regenerative power.
摘要:
In method of fabricating a bipolar transistor on a semiconductor substrate, the emitter pattern is formed using the horizontal etching effect and filling-in effect of the RF-bias sputtering method, so a fine, self-aligned emitter pattern can be created that is disposed entirely in the center of the active base region without the use of photoetching. In addition, the passive base layer and the emitter layer can approach each other to any desired degree as long as they do not touch, so no high-concentration base layer is necessary, the base resistance is reduced, and the passive base region is reduced to a very small size. Furthermore, after the formation of the base region, the only heat treatment step that alters the diffusion layer profile is the formation of the emitter layer, so the use of a thin epitaxial layer to reduce the collector resistance does not result in proximity of the buried collector layer and the passive base layer.
摘要:
In a process of fabricating a semiconductor IC having a plurality of metal wiring conductor layers on a semiconductor substrate and an insulation layer between the metal wiring conductor layers, the insulation layer being formed of a silicon oxide film is formed by means of RF bias-sputtering, a silicon oxide film is formed by means of RF bias sputtering under such a condition that the deposition rate and the etching rate on a pattern surface 45.degree. inclined with respect to the reference surface of the semiconductor substrate are equal, part of the silicon oxide film over the underlying metal wiring conductor layer being protruded; a trench is formed in part of the silicon oxide film covering the metal wiring conductor layer, and the silicon oxide is etched by RF bias sputtering under such a condition that the deposition rate and etching rate on a pattern surface parallel to the reference surface of the semiconductor substrate are equal, until the protrusion of the silicon oxide film over the metal wiring conductor is removed so that the entire silicon oxide film is planarized.
摘要:
A bi-polar transistor structure in a superhigh speed logic integrated circuit, and a process for producing the same are disclosed. The transistor has a substantially coaxial symmetric structure. Single crystal active layers as base and collector regions have peripheries surrounded wholly or partially by respective polycrystalline electrode layers. The polysilicon electrodes have lateral portions and downward depending portions that connect to single crystal layers. The polycrystalline electrode layers are separated from each other by insulation. One process for producing the structure uses only thin film forming techniques and etching techniques to dispose the active layers, an emitter electrode layer, parts of the other electrode layers and parts of the insulating layers inside a recess formed in an insulating layer formed on a substrate. Another process uses a photoetching technique by which polycrystalline layers for base and collector electrodes are patterned. Around the patterned polycrystalline electrode, side wall insulating layers are formed in the respective later steps.