Abstract: A control for controlling the DC output voltage of a boosting active filter constant. When a load changes from a rated condition to a light load or a no-load condition and the output voltage rises, a conventional active filter control device externally forces the active filter to stop and restart to suppress the voltage rise. In this process, an excessive inrush current occurs and the reactor produces abnormal sound. In addition, the conventional technique cannot be adapted to the PAM control. Accordingly, in the disclosed control of an active filter, first and second resistors and a control power supply are provided between an output terminal of a main circuit and ground, and the voltage at a node is input to one input end of a first differential amplifier and one input end of a hysteresis comparator. The output of the comparator is connected to an output end of a second differential amplifier through a signal line.

Abstract: In order to obtain a miniature unit having a simple structure which can operate at a high speed at a low cost, a copper pattern (225) provided on a power substrate (221) having a DBC substrate structure is exposed on an outer surface of the unit. Thus, it is possible to discharge heat which is generated in a main circuit of the unit to the exterior without providing a copper base plate by mounting the unit so that the pattern (225) is directly in contact with an external heat slinger or the like. The power substrate (221) is not deformed following its temperature change, since no copper base plate is required. Thus, no S-bent structure is required for a terminal which is connected with the circuit or the like, whereby speed increase and miniaturization are enabled, while the structure is simplified since no silicone gel is required.

Abstract: An insulating metallic board 160 mounting IGBTs which control an electrical power and other circuit elements and an insulating board 170 mounting semiconductor elements which control the IGBTs and the other circuit elements are arranged adjacent to or closely parallel to each other, and combined by a frame 180 into one integral circuit board to define a composite board 150. Wiring patterns 161 and 171 on which the respective circuit elements are to be disposed are formed on major surfaces of the same side. Since the composite board 150 which includes the two different types of circuit boards can be treated simply as one board, it is possible to mount the circuit elements onto the two different types of boards at the same time in one fabrication step. Thus, the number of fabrication steps and a manufacturing cost are reduced.

Abstract: In a semiconductor power module, a surge voltage on a power source line of a semiconductor element for electric power control is restrained. A power source terminal PS(NP) is comprised of power source terminals PS(P) and PS(N) which are arranged adjacent each other through an insulative sheet INS1 made of insulative synthetic resin or the like. The power source terminals PS(P) and PS(N) are each formed by a conductive plate and respectively transmit a positive and negative power source potentials. The thickness of the insulative sheet INS1 is 0.5 mm to 1.5 mm, for instance. A reduction is made in a parasitic inductance which is present in the power source line which extends from the power source terminal PS(P) to the power source terminal PS(N) through the semiconductor element for electric power control, thereby suppressing a surge voltage which is developed between the power source terminal PS(P) and the power source terminal PS(N).

Abstract: In a circuit board having four-layered conductive pattern on which a control circuit is arranged, wiring sub-patterns 133a in the first layer are divided into four areas A1-A3 and A8, for respective sets of circuit parts having same power potentials. Respective sub-patterns belonging to the areas A1-A3 are partially or fully surrounded by wiring sub-patterns PEa1 PEa3 connected to negative power potentials of circuit parts belonging to respective areas, respectively. Similarly, at least part of a wiring patten Pa2 for transmitting an input signal to a semiconductor active element is surrounded by a wiring pattern PEa4. Penetration of electric noises to the wiring patterns for the control circuit, in particular to the wiring pattern for transmitting the input signal to semiconductor element, is decreased to thereby prevent misoperation due to electric noises.

Abstract: A multilayer substrate (18) has two ceramic plates (111, 114) and a shielding metal layer (113) provided between the ceramic plates. An electronic circuit having a TRIAC (7) and a photocoupler (5) is provided on the multilayer substrate. The shielding metal layer and a second main electrode (T.sub.2) of the TRIAC are connected with each other by solder filled in a through hole 116. External noise is captured by the shielding metal layer, to be propagated to the second main electrode.

Abstract: A starting control apparatus for an AC load includes a bidirectional triode thyristor switching device connected in series between an AC power source and the load, a rectifying circuit connected in parallel to the bidirectional triode thyristor switching device, a first time constant circuit connected between output terminals of the rectifying circuit which discharges to turn on the bidirectional triode thyristor switching device when the charged potential reaches a predetermined potential, a second time constant circuit connected between the output terminals of the rectifying circuit and having a time constant larger than the time constant of the first time constant circuit and maintaining the charged potential in the ON state of the bidirectional triode thyristor switching device, and a speedy charging device which rapidly increases the charged potential to the sustaining potential of the second time constant circuit during the recharging period for the first time constant circuit while recovering the contr