JP2009268239A - Semiconductor module and power unit equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor module, which effectively absorbs a surge caused by the operation of a switching element constituting a PFC circuit and eliminates the sudden rise of its cost, and a power unit, which is equipped with the semiconductor module. <P>SOLUTION: A semiconductor module Ms is composed of a switching element Tq, a diode DP, a surge suppressing capacitor Cn, and an inverter circuit Inv, and further it is provided properly with terminals a-b for capacitors, a terminal to be connected with a rectifier circuit DB, a terminal to be connected with a control motor M, etc. Then, a surge suppressing capacitor Cn is connected in parallel with a switching element Tq and to accommodate it inside the semiconductor module Ms, and a wiring path from the switching element Tq to the surge suppressing capacitor Cn is shortened. Accordingly, in the surge suppressing capacitor Cn, reactance components parasitic on a wiring board reduce, and surge components, which are generated according to the drive operation of the switching element Tq, are absorbed effectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor module and a power supply device including the semiconductor module, and is particularly suitable for use in effectively absorbing a surge generated in a circuit.

  A control motor used for home appliances is connected to a power supply device including a PFC circuit and an inverter circuit, and is driven by electric power converted into an appropriate state by the power supply device. In such a power supply device, the power factor and voltage value of the commercial power supply are improved by the PFC circuit, and further converted into desired AC power by the inverter circuit.

  Japanese Patent Laying-Open No. 2006-197729 (Patent Document 1) introduces an example of such a power supply device. The motor drive device described as a power supply device includes a first rectifier circuit (rectifier circuit in claims), a reactor (reactor in claims), and a second rectifier circuit (diode in claims). ), A switching element, a surge protection component (surge suppression capacitor in claims), an electrolytic capacitor, an inverter device (inverter circuit in claims), and various control circuits, and a circuit board It is laid out inside and outside. At this time, the PFC circuit is configured by the reactor, the second rectifier circuit, the switching element, and the electrolytic capacitor. In such a motor drive device, since the first rectifier circuit, the second rectifier circuit, the switching element, and the inverter device are constituted by semiconductor elements, a semiconductor module in which these semiconductor elements are integrated is used. And as shown in FIG. 4 of patent document 1, since an electrolytic capacitor, a varistor, and a reactor are made into a big physique compared with a semiconductor element, they will be arrange | positioned outside a semiconductor module.

JP 2006-197729 A

  In the switching element constituting the PFC circuit, when the switching element is driven by the control circuit, when the switching element is turned on, a sudden change in the current value occurs according to the switching speed, and a surge is generated in the current waveform in the vicinity of the turn-on time. appear.

  On the other hand, when the switching element is turned off, the collector-emitter voltage Vce increases according to the switching speed, and a surge voltage is generated in the voltage Vce at the end of the turn-off operation.

  Therefore, in the technique of Patent Document 1, since the surge protection unit is arranged outside the semiconductor module in the technique of Patent Document 1, there is a wiring path from the switching element of the PFC circuit, which is one of the surge generation sources, to the smoothing capacitor. Accordingly, the smoothing capacitor is greatly affected by the reactance component parasitic on the substrate wiring, and the problem that the surge component generated due to the operation of the switching element cannot be sufficiently absorbed occurs. . Moreover, it is difficult to improve the waveform in the frequency region where it is desired to suppress the surge in an electrolytic capacitor that is widely used as a smoothing capacitor.

  In addition, in such a semiconductor module, it is conceivable to reduce the switching speed when operating the switching element in order to suppress the surge component. However, in this case, since the amount of heat generated in the switching element increases, Therefore, measures must be taken to improve heat dissipation or heat resistance. Here, when the heat dissipation is improved, the heat dissipation mechanism is enlarged, and when the heat resistance is improved, it is necessary to increase the element size of the switching element. As a result, the cost is increased. Occurs.

  Furthermore, in the power supply device including the semiconductor module, when a surge is generated by the switching element constituting the PFC circuit, the surge is also superimposed on the current flowing through the inverter circuit. Therefore, depending on the magnitude of the surge, the inverter circuit This causes a problem that the control circuit for driving is shifted to the stop mode and the control motor is not driven properly.

  Therefore, in view of the above-described problems, the present invention effectively absorbs surges caused by the operation of the switching elements constituting the PFC circuit and eliminates the increase in cost, and a power supply device including the semiconductor module. For the purpose of provision.

  In order to solve the above problems, the present invention has the following semiconductor module configuration. That is, a switching element that interrupts input power at high speed, a surge suppression capacitor that is connected in parallel to the switching element and absorbs high-frequency surge, an anode side is connected to an input terminal of the switching element, and a cathode side is the surge suppression capacitor A diode connected to the capacitor, a capacitor terminal connected in parallel to the switching element at the subsequent stage of the diode, and a direct current supplied from the smoothing capacitor connected to the subsequent stage of the surge suppression capacitor An inverter circuit that converts electric power into AC power is used.

  At this time, it is preferable that the semiconductor module is further provided with a rectifier circuit connected in parallel to the previous stage of the switching element and rectifying the AC power supplied from the power source.

  At this time, the surge suppression capacitor is preferably a ceramic capacitor.

  In the present invention, the power supply device has the following configuration. That is, at least the semiconductor module according to any one of the above-described inventions, a reactor and the smoothing capacitor arranged outside the semiconductor module are provided.

  At this time, it is preferable that a surge countermeasure component is mounted between the smoothing capacitor and the capacitor terminal.

  According to the semiconductor module of the present invention, since the surge suppression capacitor is stored inside the semiconductor module, the wiring of the wiring from the switching element, which is a surge source, to the surge suppression capacitor is shortened. The parasitic reactance component is reduced, thereby effectively absorbing the surge component generated in accordance with the driving operation of the switching element.

  Further, according to such a semiconductor module, since the switching speed can be set at a high speed, heat generation of the switching element can be suppressed, and thereby the size of the element of the switching element can be reduced and the cost can be reduced. Is done.

  Further, in the power supply device including such a semiconductor module, the surge component generated due to the operation of the switching element is absorbed by the surge suppression capacitor, so that the DC power output from the PFC circuit is attributed to the operation of the switching element. The surge is eliminated, and thus the inverter circuit can stably output the AC power supply.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the power supply device according to the present embodiment. In the power supply device X, the rectifier circuit DB, the reactor L, the smoothing capacitor C0, and the semiconductor module Ms are mounted on the circuit board Bp.

  As shown in the figure, the rectifier circuit DB includes four diodes in a bridge shape, and a commercial power source is connected to a pair of terminals. The high side line LH is connected to the output side of the other pair of terminals, and the high side line LH is connected to the semiconductor module Ms via the reactor L. Furthermore, the return side of the other pair of terminals is connected to the semiconductor module Ms via the low side line LL. In such a rectifier circuit DB, AC power supplied from the commercial power source E is converted into a full-wave waveform.

  Reactor L accumulates energy obtained from AC power and boosts smoothing capacitor C0 according to the operation of switching element Tq. The reactor L is mounted outside the semiconductor module Ms and on the surface of the circuit board Bp.

  As with the reactor L, the smoothing capacitor C0 is mounted outside the semiconductor module Ms and on the surface of the circuit board Bp. Such a smoothing capacitor C0 requires a relatively large electric capacity of several hundred μF to several thousand μF, and an element having a large outer dimension such as an electrolytic capacitor is selected, so that it is laid out outside the semiconductor module Ms. Is done.

  The semiconductor module Ms includes a switching element Tq, a diode DP, a surge suppression capacitor Cn, and an inverter circuit Inv. The semiconductor module Ms is appropriately provided with capacitor terminals a and b, terminals connected to the rectifier circuit DB, terminals connected to the control motor M, and the like.

  Each terminal connected to the rectifier circuit DB is laid out at a position where it can be electrically connected to the outside of the semiconductor module Ms, and one is connected to the high side line LH and the other is connected to the low side line LL.

  As the switching element Tq, a power semiconductor element such as IGBT or MOSFET is used. The input terminal of the switching element Tq is connected at a contact point between the reactor L and the diode DP, and the output terminal of the switching element Tq is connected to the low side line LL immediately after the other terminal connected to the rectifier circuit DB. Is done. Specifically, for example, when an IGBT is used as the switching element Tq, the IGBT has a collector terminal connected to the high side line LH, an emitter terminal connected to the low side line LL, and a gate terminal connected to a control circuit (not shown). Is done. Such an IGBT receives an appropriately calculated drive signal from the control circuit and intermittently powers input from a terminal connected to the rectifier circuit DB.

  The diode DP is arranged on the high side line LH side, the anode side is connected to the input terminal of the switching element Tq, and the cathode side is connected to the surge suppression capacitor. The rectifying element DP supplies the electric power converted by the reactor L to a subsequent circuit, and prevents the electric charge accumulated in the smoothing capacitor C0 from flowing backward to the anode side of the high side line LH.

  The surge suppression capacitor Cn is connected in parallel to the switching element Tq, and a small capacitance element of about several pF to several tens of μF is used. As described above, since a small-capacitance element is used, the element size can be reduced and stored in the semiconductor module Ms. Here, it is preferable to employ a ceramic capacitor as the surge suppression capacitor Cn. As a result, the surge control capacitor Cn achieves a reduction in the element size and contributes to the miniaturization of the semiconductor module Ms. Further, since the surge control capacitor Cn is also improved in frequency characteristics, surge absorption performance in a high frequency region is improved.

  The capacitor terminal a is electrically connected to the high side line LH. The capacitor terminal b is connected to the low side line LL. The terminals a and b are laid out so as to be electrically connected to the outside of the semiconductor module Ms, and are connected in parallel to the smoothing capacitor C0 mounted on the circuit board Bp. As shown in the figure, the conduction point of the capacitor terminals a and b may be immediately after the surge suppression capacitor Cn. The conduction point is connected to the capacitor terminal a immediately after the cathode of the rectifying element DP. The capacitor terminal b may be connected immediately after the output terminal of the switching element Tq.

  In the inverter circuit Inv, a set of transistors Ti is connected in series, and three sets of such series circuits are connected in parallel. As the switching element Ti, a semiconductor element such as IGBT or MOSFET is appropriately employed. Each series circuit has a high side line LH connected to the upper end and a low side line LL connected to the lower end. Then, power supply lines U, V, and W are drawn out from the contacts of each series circuit, and are connected to terminals laid out so as to be connected to the control motor M. As shown in the figure, the inverter circuit Inv is connected to the subsequent stage of the surge suppression capacitor Cn. Based on the control command of the inverter control circuit (not shown), the inverter circuit Inv converts the DC power supplied from the smoothing capacitor C0 provided outside into AC power. Convert it.

  In the semiconductor module Ms having such a configuration, when the switching element Tq is driven by the control circuit, a surge is generated in the current waveform according to the switching speed when the switching element Tq is turned on. At this time, since the surge suppression capacitor Cn is laid out in the semiconductor module Ms and in the immediate vicinity of the switching element Tq, the substrate wiring from the switching element Tq to the surge suppression capacitor Cn is remarkably shortened. . Therefore, in the substrate wiring, since the parasitic reactance component is suppressed to a very low value, the impedance leading to the surge suppression capacitor Cn is set to a low value, so that when the surge component is superimposed on the current at turn-on, The surge component is accumulated as a charge amount in the surge suppression capacitor Cn, and is effectively attenuated accordingly.

  On the other hand, when the switching element Tq is turned off, the collector-emitter voltage Vce increases according to the switching speed, and a surge voltage is generated in the voltage Vce at the end of the turn-off operation. The surge voltage is proportional to the reactance and the temporal change in current. In the semiconductor module Ms of this embodiment, the parasitic reactance component from the switching element Tq to the surge suppression capacitor Cn has a low value. As a result, the fluctuation range related to the surge voltage is suppressed as a result.

  That is, even if the switching speed of the switching element Tq is increased and the time required for turn-on or turn-off is shortened, the surge component of the current or voltage generated thereby is disposed by the surge suppression capacitor Cn. It will be effectively suppressed.

  In the power supply device X including the semiconductor module Ms, the rectifier circuit DB is arranged after the terminal connected to the commercial power supply E, and in the subsequent stage, the reactor L and the smoothing capacitor C0 mounted on the circuit board Bp The PFC circuit is configured by the switching element Tq, the diode DP, and the surge suppression capacitor Cn stored in the semiconductor module Ms, and the inverter Inv circuit stored in the semiconductor module Ms is arranged in the subsequent stage of the PFC circuit. The The power supply lines U, V, W wired to the inverter Inv circuit are electrically connected to the control motor M.

  In such a power supply device X, when AC power is supplied from a commercial power supply, the rectifier circuit DB converts the AC power into a full-wave waveform and outputs the full-wave power to the PFC circuit. In such a PFC circuit, the switching element Tq is appropriately driven to supply the energy accumulated in the reactor L to the smoothing capacitor C0, and the smoothing capacitor C0 supplies the smoothed and boosted DC power to the inverter circuit Inv. To output. At this time, in the PFC circuit, a surge current or a surge voltage is generated according to the operation of the switching element Tq, but the surge current or the surge voltage is effectively absorbed by the surge suppression capacitor Cn. Therefore, since the surge component is eliminated as much as possible in the DC power output from the smoothing capacitor C0, the inverter circuit Inv outputs a stable drive signal without shifting the inverter control circuit to the emergency stop mode. The plurality of transistors Ti constituting the inverter circuit Inv are appropriately driven. Therefore, in the inverter circuit Inv, the DC power source is converted into a three-phase AC power source, and the control motor M disposed in the subsequent stage is appropriately controlled by the three-phase AC power source.

  As described above, in the semiconductor module Ms according to the present embodiment, since the surge suppression capacitor Cn is stored inside the semiconductor module Ms, wiring from the switching element Tq, which is a surge generation source, to the surge suppression capacitor Cn. Along with the shortening of the path, the reactance component parasitic on the substrate wiring is reduced, thereby effectively absorbing the surge component generated according to the driving operation of the switching element Tq.

  Further, in such a semiconductor module Ms, since the switching speed can be set at a high speed, the heat generation of the switching element Tq can be suppressed, whereby the element size of the switching element Tq can be reduced and the cost can be reduced. It becomes possible.

  Furthermore, in the power supply device Bp including the semiconductor module Ms, the surge component generated due to the operation of the switching element Tq is absorbed by the surge suppression capacitor Cn, so that the DC power output from the PFC circuit is the current of the switching element Tq. Surge due to the operation is eliminated, and thus the inverter circuit Inv can stably output the AC power supply.

  FIG. 2 shows another configuration example of the smoothing capacitor C0 mounted outside the semiconductor module Ms. The smoothing capacitor C0 is connected in parallel with a snubber circuit (a surge countermeasure component in the claims) comprising a resistor R and a capacitor Cs connected in series. When a surge component is superimposed on the current flowing into the smoothing capacitor C0, the snubber circuit temporarily absorbs the surge component and then slowly discharges the direct current power output from the smoothing capacitor C0. Stabilize. A ferrite core (surge countermeasure component in claims) Ln is provided between the snubber circuit and the smoothing capacitor C0. The ferrite core Ln reduces a radiation surge that is generated when a current flows through the substrate wiring.

  In such a case, since the surge due to the operation of the switching element Tq has already been reduced in the semiconductor module Ms, the selection of the snubber circuit or the ferrite core Ln can be changed to a small element physics. A circuit board can be reduced in size and cost can be reduced.

  The semiconductor module according to the present invention is not limited to the above-described configuration, and various modifications can be made. For example, the semiconductor module Ms described in the present embodiment includes the switching element Tq, the diode DP, the surge suppression capacitor Cn, and the inverter circuit Inv. However, the configuration is changed, and the rectifier circuit DB and the switching element are changed. A new semiconductor module including Tq, diode DP, surge suppression capacitor Cn, and inverter circuit Inv may be used. In such a new semiconductor module, all the semiconductor chips such as the diode constituting the rectifier circuit DB, the switching element Tq, the diode DB, and the transistor Ti constituting the inverter circuit are integrated inside the semiconductor module. The mounting process is unified, thereby simplifying the manufacturing process in the power supply device.

The figure which shows the structure of the power supply device which concerns on embodiment Diagram showing the configuration of the circuit connected to the capacitor terminal

Explanation of symbols

Ms Semiconductor module Tq Switching element Cn Surge suppression capacitor Dp Diode C0 Smoothing capacitor
a Capacitor terminal
b Capacitor terminal Inv Inverter circuit Bp Power supply DB Rectifier circuit
L reactor

Claims (5)

  A switching element that intermittently cuts input power at high speed, a surge suppression capacitor that is connected in parallel to the switching element to absorb high-frequency surges, an anode side is connected to the input terminal of the switching element, and a cathode side is connected to the surge suppression capacitor A diode terminal, a capacitor terminal for connecting a smoothing capacitor arranged outside to the switching element in parallel at the subsequent stage of the diode, and a DC power supplied from the smoothing capacitor connected to the subsequent stage of the surge suppression capacitor. A semiconductor module comprising an inverter circuit for converting to AC power.   A semiconductor module, further comprising a rectifier circuit connected in parallel to the previous stage of the switching element and rectifying AC power supplied from a power source.   The semiconductor module according to claim 1, wherein the surge suppression capacitor is a ceramic capacitor.   A power supply apparatus comprising: at least the semiconductor module according to claim 1; a reactor disposed outside the semiconductor module; and the smoothing capacitor.   The power supply device according to claim 4, wherein a surge countermeasure component is mounted between the smoothing capacitor and the capacitor terminal.

Images