JP2011090890A - Direct current switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC switch capable of two-wire wiring in an indoor wiring of an embodiment in which a load and the DC switch are separated in remote positions. <P>SOLUTION: The DC switch SW is equipped with a semiconductor switching element Q1 which is connected in series to a load L to the DC power source DC, a charging circuit CH which is connected in parallel to the semiconductor switching element, a charging part CE which is connected to the charging circuit and is charged at the time of switching off of the semiconductor switching element, a driving circuit DR which is energized by the charging part and turns on the semiconductor switching element, and an operating switch OP which controls action of the driving circuit to the semiconductor switching element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a DC switch that opens and closes a load connected to a DC power source via a DC line.

  A DC switch that opens and closes a load connected to a DC power source using a DC switch circuit made of a MOSFET is known (see Patent Documents 1 and 2).

  As shown in FIG. 8, the first DC switch described in Patent Document 1 is the first plug of the plug behind the first contact 14 connected to the positive electrode side of the DC power source of the outlet 1. A third contact 16 is provided at a position where the terminal 21 contacts, and the outlet second contact 15 is connected to the negative side of the DC power supply via the MOSFET 11, and this MOSFET is connected between the third contact 16 and the negative side potential. The voltage is controlled by applying a potential by a voltage dividing resistor connected to the gate electrode to the gate electrode.

  As shown in FIG. 9, the second DC switch described in Patent Document 2 is provided with a power MOSFET Q1 in the middle of a negative electrode wire L2 that supplies DC power, and the source S of the power MOSFET Q1 is on the power supply side. The drain D is connected to the electric equipment side, and the connection point of the resistors R1 and R2 is connected to the gate G and the source S of the power MOSFET Q1, respectively, and between the connection point of each resistor and the source S of the power MOSFET Q1. The switch SW is interposed, and the switch SW is applied from the state in which the divided voltage of the resistor R1 and the resistor R2 can be applied to the gate G of the power MOSFET Q1 by the opening and closing operation of the switch SW by the switch operation unit 5a. Thus, a state in which the divided voltage of the resistor R1 and the resistor R2 is applied to the gate G of the power MOSFET Q1 by the operation of the switch SW from the opening to the closing by the switch operation unit 5a. It is configured to be ready for al application.

JP 2003-203721 A JP 2005-293317 A

  However, the first and second DC switches in the prior art have the following problems. That is, the conventional first DC switch is built in the outlet, and cannot be directly opened or closed unless a user or the like removes the plug. Further, since the MOSFET of the semiconductor switch has a parasitic capacitance, there is a problem that when the plug is inserted into the outlet for supplying electric power to the electric device, the MOSFET is turned on due to noise and an arc is generated in the outlet.

  On the other hand, the conventional second DC switch is applied to an operation switch connected in the middle of a cord with a plug attached to a load device to be plugged into an outlet, and is difficult to apply to an indoor wall switch. There is. That is, in the second DC switch, a gate circuit including a series circuit of resistors R1 and R2 and a capacitor C connected in parallel to the resistor R2 is connected between the positive line L1 and the negative line L2. . For this reason, there is a problem that the two-wire wiring cannot be performed in the indoor wiring in a mode in which the load and the DC switch are separated at a remote position.

  An object of the present invention is to provide a DC switch capable of two-wire wiring.

  In order to solve the above problems, a DC switch according to the present invention includes a semiconductor switch element connected in series to a load with respect to a DC power source; a charging circuit connected in parallel to the semiconductor switch element; and a semiconductor connected to the charging circuit. A charging unit that is charged when the switch element is turned off; a drive circuit that is energized by the charging unit to turn on the semiconductor switch element; and an operation switch that controls the action of the drive circuit on the semiconductor switch element.

  In the present invention, a semiconductor switch element is used as a means for opening and closing the load, and the line voltage connected to the DC power supply appears between both ends when the semiconductor switch element is turned off. The charging unit for energizing the drive circuit of the semiconductor switch element is charged in advance. In particular, when the semiconductor switch element is a voltage drive type such as a MOSFET, the power required to drive the semiconductor switch element is very small, and a secondary battery, an electrolytic capacitor or an electric double layer capacitor is provided in the charging part. Since the selection can be made as appropriate, the semiconductor switch element can be turned off at a desired time even if the semiconductor switch element is kept on for a certain long period of time. It should be noted that the present invention is allowed to be an embodiment in which the following configuration is selectively added in addition to the above essential configuration. This is advantageous because the function is further improved.

  In the first aspect of the present invention, a voltage drop is generated at both ends of the semiconductor switch element while maintaining the semiconductor switch element substantially in an ON state, and charging is performed by applying a voltage to the charging circuit using the voltage drop. On-time charging means for charging the unit is provided.

  In the first aspect, even if the semiconductor switch element continues to be in an ON state for a long period exceeding a certain level, the charging unit can be charged during that period. In this aspect, maintaining the semiconductor switch element substantially in an on state means that a load composed of general electric equipment connected to a DC power source via a DC switch can operate almost normally. Within the range, a drop in voltage supplied to the load for a short time and a power supply voltage interruption for a very short time are allowed. In other words, a general electric device continues to operate even if the DC power supply voltage drops from the rated value to some extent, for example, about 10%, or even if the instantaneous interruption compensation time is cut off, for example, about several tens of milliseconds. Since it is configured, it can be said that there is no problem as long as the voltage drop or the short interruption is performed.

  In the first aspect of the present invention, a preferable standard for maintaining the semiconductor switch element substantially in the on state is as follows. That is, the voltage applied to the load via the semiconductor switch element is in a state where the voltage supplied to the load is reduced by 5 to 10% in a steady state or a rated value, or the voltage supplied to the load is generally several milliseconds or less More preferably, it is in a state of instantaneous interruption for about 100 μsec. In addition, the time during which the voltage supplied to the load decreases is not particularly limited, but it is preferable that the time is as short as possible within a range where the required charging can be performed.

  In order to reduce the load applied voltage, the drive signal of the semiconductor switch element may be controlled to increase the impedance across the semiconductor switch element. Then, although the voltage applied to the load is slightly reduced, the semiconductor switch element can be substantially maintained in the on state. At the same time, when the impedance of the semiconductor switch element is increased, a load current flows there, so that a voltage drop is generated by subtracting the load voltage between both ends of the semiconductor switch element. The charging unit can be charged by this voltage drop.

  Further, the semiconductor switch element can be substantially maintained in the ON state by turning off the semiconductor switch element for a very short time instead of the above. Since at least the entire line voltage is applied across the semiconductor switch element during the off period, the charging unit can be charged using this period even for a short time.

  Note that the charging unit can be charged by intermittently providing a plurality of occasions for maintaining the semiconductor switch element substantially in an ON state as necessary.

  The trigger for starting charging of the charging unit may be either confirmation or prediction of the voltage drop of the charging unit. In order to confirm the voltage drop, the voltage detecting means is provided in the charging unit so that the semiconductor switch element is substantially maintained in the ON state when the voltage falls below a predetermined value. On the other hand, in order to predict a voltage drop, a timer that starts timing when the DC switch is turned on is provided, and the semiconductor switch element is substantially kept on every time a predetermined time elapses. To be configured.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, there is provided a charging unit voltage detecting unit that detects the voltage of the charging unit and operates the on-time charging unit when the detected voltage falls below a predetermined value. It has.

  The second aspect is configured such that charging is performed when the voltage of the charging unit drops to a level that requires charging, for example, when the ON state is continued for a considerably long period of time.

  According to a third aspect of the present invention, in addition to the configuration of any one of the present invention, the first and second aspects, a semiconductor switch element voltage detecting means for detecting a voltage across the semiconductor switch element; and a semiconductor switch element The normal line voltage when the semiconductor switch element is off is measured in advance by the semiconductor switch element voltage detecting means, and the semiconductor switch when the line voltage when the semiconductor switch element voltage detecting means is turned off from the on state exceeds the normal line voltage. Semiconductor switch element impedance control means for controlling the impedance of the element.

  The third aspect is configured to suppress the occurrence of transient vibration due to kickback caused by the wiring length of the line when the semiconductor switch element is turned off.

  According to the present invention, when the semiconductor switch element is turned off, the charging unit is charged by the charging circuit connected in parallel to the semiconductor switch element, and the driving circuit is operated by using the electric energy charged in the charging unit to thereby operate the semiconductor switch element. Therefore, even if the load and the DC switch are separated from each other, only two wires are required between them, and the internal wiring is simplified so that the size can be reduced. No contactless DC switch can be provided.

According to the aspect of the present invention, in addition to the above-described effects of the present invention, the following effects are provided.
1. According to the first aspect, even when the semiconductor switch element is kept on for a long time and the voltage of the charging unit is lowered, the semiconductor switch element is substantially turned on by operating the on-time charging means. A voltage that can be used for charging appears across the semiconductor switch element. And since a charging part is charged with the said voltage, even if the ON state of a semiconductor switch element continues for a long period of time, it does not have a substantial influence on the load during conduction, and the switching function of the DC switch is impaired There is nothing.
2. According to the second aspect, the charging unit voltage detection means monitors the voltage of the charging unit. As a result, when the voltage of the charging unit falls below a predetermined value, the charging unit is operated, so that the charging unit is automatically charged when necessary.
3. According to the third aspect, when the line voltage detected by the semiconductor switch element voltage detecting means when the semiconductor switch element is turned off due to the line inductance caused by the wiring length exceeds the normal line voltage, the impedance of the semiconductor switch element Is controlled in the decreasing direction from the shut-off state. This increases the resistance of the line. As a result, since transient vibration is suppressed, it is possible to protect the load by reducing or preventing an overvoltage from being applied to the load without using a special surge absorber. In addition, when transient vibration does not occur when the semiconductor switch element is turned off, the semiconductor switch element maintains the cutoff state, so that the impedance is not controlled in a decreasing direction. It is possible to avoid wasteful power consumption in the transition period when the conventional technology for suppressing the generation of voltage is adopted.

1 is a block circuit diagram conceptually showing the present invention. It is an electrical wiring diagram of room lighting as one example of use of the DC switch of the present invention. It is a circuit diagram showing the 1st form for carrying out the present invention. It is a circuit diagram which shows the 2nd form for implementing this invention. It is a circuit diagram which shows the 3rd form for implementing this invention. It is a circuit diagram which shows the 4th form for implementing this invention. It is a circuit diagram which shows the 5th form for implementing this invention. It is a circuit diagram which shows the conventional 1st DC switch. It is a circuit diagram which shows the 2nd conventional DC switch.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, the present invention will be described with reference to FIG.

  That is, the DC switch SW of the present invention includes a semiconductor switch element Q1, a control circuit CC, a charging unit CE, and an operation switch OP. The control circuit CC is a circuit that includes the charging circuit CH and the driving circuit DR.

  The semiconductor switch element Q1 is connected in series with a load L to a direct current line l extending from the direct current power source DC. Further, the specific configuration of the semiconductor switch element Q1 is not particularly limited. For example, a semiconductor element such as a MOSFET, a transistor, or a GTO can be used. In particular, since the MOSFET can be turned on by voltage driving, it is suitable for the demand for downsizing and cost reduction of the charging unit CE.

  Among the control circuits CC, the charging circuit CH is connected in parallel to the semiconductor switch element Q1, and operates while the semiconductor switch element Q is off to charge the charging element CE. In addition, the drive circuit DR operates using the charging unit CE as a power source to turn on the semiconductor switch element Q.

  The charging unit CE is connected to the circuit portion of the charging circuit CH in the control circuit CC and is charged when the semiconductor switch element Q1 is turned off. Further, the specific configuration of the charging unit CE is not particularly limited. For example, an electrolytic capacitor, an electric double layer capacitor, a secondary battery, and the like can be used. When a MOSFET is used for the semiconductor switch element Q1 and the DC switch SW is turned on and off on a daily basis, there is no practical problem even if an electrolytic capacitor is used as the charging unit CE.

  The operation switch OP is a means that is connected to the semiconductor switch element Q1 and the circuit portion of the drive circuit DR, and causes the drive circuit DR to act on or inactivate the semiconductor switch element Q1. That is, in FIG. 1, when the operation switch OP is turned on, the functional portion of the drive circuit is connected to the semiconductor switch element Q1, so that the semiconductor switch element Q1 is turned on. When the operation switch OP is turned off, the semiconductor switch element Q1 is turned off.

  Next, a usage example of the DC switch of the present invention will be described with reference to FIG. In FIG. 2, the same parts as those in FIG. In the figure, R is a room, LM is a lighting fixture, and WS is a wall switch.

  The luminaire LM is installed on the ceiling of the room R and embedded and wired so that the wall switch WS can be blinked. The wall switch WS includes the DC switch SW of the present invention shown in FIG.

  Thus, the wiring between the DC power source DC, the luminaire LM, and the wall switch WS is wired in two lines, and the wall switch WS is contactless by the semiconductor switch element Q1, but the operability is Can be configured to be operated by a push button, a seesaw-type handle or the like in the same manner as a generally used mechanical wall switch.

  Next, a first embodiment for carrying out the present invention will be described with reference to FIG. In the figure, the same parts as those in FIG.

  In the first embodiment, the semiconductor switch element Q1 is made of a MOSFET. Among the control circuits CC, the charging circuit CH is configured by a series circuit of a diode D1 and a resistor R1 which are forward in the illustrated polarity, that is, charging. The charging unit CE is composed of a secondary battery. In addition, as a secondary battery, a lithium ion battery etc. can be used, for example.

  The drive circuit DR has a configuration in which a resistor R2 is connected in parallel between the source and gate of a MOSFET, and a secondary battery of the charging unit CE is connected to both ends of the resistor R2 via an operation switch OP.

  Then, when the secondary battery of the charging unit CE is charged, when the operation switch OP is operated and turned off, the voltage of the secondary battery is connected between the gate and source of the MOSFET via the operation switch OP. Since it is applied as a drive voltage, the MOSFET is turned on. As a result, the load L operates. The diode D1 of the charging circuit CH prevents the secondary battery from discharging in the closed circuit of the resistor R1 and the MOSFET when the MOSFET is turned on.

  Next, when the operation switch OP is operated and opened, the drive voltage is not applied to the MOSFET, so that the MOSFET is turned off and the load L is deactivated. As a result, the voltage of the DC power supply DC appears between the drain and source of the MOSFET, so that the charging circuit CH is activated to charge the secondary battery of the charging unit CE, and then the operation switch OP is turned off. .

  Hereinafter, other embodiments for carrying out the present invention will be described with reference to FIGS. In addition, in each figure, the same part as FIG. 1 thru | or FIG. 3 is attached | subjected, and description is abbreviate | omitted.

  FIG. 4 shows a second embodiment of the present invention. In the present embodiment, in contrast to the first embodiment, the charging circuit CH is configured by a series circuit of a resistor R1 and one fixed contact and a movable contact located above in the figure of the switching operation switch OP. ing. The charging unit CE is configured by an electrolytic capacitor or an electric double layer capacitor. The drive circuit DR is connected to the positive electrode of the charging element CE through the other fixed contact and the movable contact located below the switch-type operation switch OP in the connection point of the resistor R2 and the gate. This is different from the first embodiment.

  Thus, when the operation switch OP is operated to the position shown in the drawing, the drive circuit DR is opened and no drive voltage is applied to the MOSFET of the semiconductor switch element Q1, so that the MOSFET is turned off and the load L is ineffective. It becomes operation. At the same time, since the drain-source voltage of the MOSFET increases to the voltage of the DC power supply DC, the charging circuit CH is activated to charge the charging unit CE.

  Next, when the operation switch OP is operated and the movable contact comes into contact with the other fixed contact located below the illustrated position, the charging unit CE is connected to the drive circuit DR, so that the MOSFET of the semiconductor switch element Q1 is turned on. The load L is activated. Accordingly, since the charging circuit CH is opened by the operation switch OP, the charging unit CE does not undesirably discharge the charging circuit CH and the closed circuit of the MOSFET.

  FIG. 5 shows a third embodiment of the present invention. In the present embodiment, the on-time charging means OC is provided. The on-time charging unit OC includes a charge command unit CI and a substantially on-state switching unit SOC.

  In this embodiment, the charging command means CI is constituted by a charging unit voltage detecting means. The charging unit voltage detecting means can be constituted by a voltage comparator, for example, and sends a detection signal as a charging command when the voltage of the charging unit CE falls below a predetermined value set in advance. The predetermined value is preferably set to be equal to or higher than the lower limit value of the value at which the output voltage of the charging unit CE can reliably turn on the semiconductor switch element Q1 with the required high conductivity.

  In addition, the charging unit voltage detection means is charged only when the semiconductor switch element Q1 is on by detecting the voltage across the charging unit CE via the operation switch OP as desired instead of the connection mode shown in FIG. The voltage detection operation of the part CE can be performed. Moreover, a hysteresis characteristic can be provided to the detection voltage as desired. Thereby, it is allowed to be configured to stop the transmission of the detection signal when the voltage of the charging unit becomes higher to the second detection voltage that is higher than the first detection voltage when the detection signal is transmitted. . According to this modification, the stability of the charging operation and the reliability of charging can be improved.

  The substantially on-state switching means SOC receives the command from the charge command means CI and turns off the semiconductor switch element Q1 turned on by the operation of the operation switch OP for a very short time or between both ends of the semiconductor switch element Q1. This is means for changing the impedance to an on-state substantially by increasing the impedance within an allowable range. For example, as shown in the figure, the substantially on-state switching means SOC can be configured using the monostable multivibrator SMB and the switch element Q2. The monostable multivibrator SMB outputs a pulse voltage having a predetermined time width in response to the detection signal of the charge command means CI. If desired, the time width of the output voltage pulse of the monostable multivibrator SMB can be variably configured. The switch element Q2 is inserted in series between the operation switch OP and the semiconductor switch element Q, and is turned off in synchronization with the pulse voltage output of the monostable multivibrator SMB.

  Next, the circuit operation in the third embodiment will be described. If the voltage of the charging unit CE falls below a predetermined value while the operation switch OP is turned off and the semiconductor switch element Q1 is kept on, the charge command means CI detects this and outputs a charge command consisting of a detection signal.

  When the charge command is output, the substantially on-state switching means SOC responds to the pulse voltage having a predetermined time width generated from the monostable multivibrator SMB. Since the switching element Q2 is turned off for a short time by the control in response to the pulse voltage, the gate potential of the semiconductor switching element Q1 becomes equal to the source potential, so that the semiconductor switching element Q1 shifts to a substantially on state in which it is turned off for a very short time. .

  When the semiconductor switch element Q1 is turned off for a very short time, since the voltage across the semiconductor switch element Q1 is at least equal to the line voltage, the charging circuit CH is activated and the charging unit CE is charged. With this charging operation, the voltage of the charging unit CE is recovered. When inductance is present in the load circuit due to the wiring length or the like, a transient oscillation voltage higher than the power supply voltage is generated across the semiconductor switch element Q1 by kickback when the semiconductor switch element Q1 is turned off. Therefore, charging of the charging unit CE is further promoted.

  In addition, when the circuit is configured so that the continuity of the switch element Q2 is lowered for a short time corresponding to the pulse output voltage of the monostable multivibrator SMB, the gate and source of the semiconductor switch element Q1 are connected. Since the applied voltage is lowered, the impedance between both ends of the semiconductor switch element Q1 is increased for a short time. Accordingly, the voltage drop across the semiconductor switch element Q1 becomes, for example, about 5 to 10% at a DC power supply voltage of about 50 to 100 V, for example, and the drive voltage of the semiconductor switch element Q1 is about several to tens of volts. Therefore, it is possible to operate the charging circuit CH with the voltage between both ends and to generate a drive signal for the semiconductor switch element Q1 using the charging unit CE as a power source.

  FIG. 6 shows a fourth embodiment of the present invention. In the present embodiment, the charge command means CI ′ is different from that in the third embodiment.

  That is, the charging command means CI ′ of the present embodiment is constituted by a timer, and automatically charges the charging unit CE when a predetermined time set in advance elapses. For this reason, the charging command means CI ′ is connected to the charging unit CE serving as a power source via the operation switch OP, and is configured to perform the time measuring operation only when the semiconductor switch element Q1 is in the ON state. . The predetermined time of the timer is preferably set as follows. That is, when the voltage of the charging unit CE is in the continuous ON state of the semiconductor switch element Q1, the electric energy stored in the charging unit CE is consumed by continuously driving the semiconductor switch element Q1, and the semiconductor switch element In consideration of the passage of time that may cause the voltage to fall below the required voltage for normally driving Q1, a slightly shorter time can be set.

  Thus, in the fourth embodiment, when the operation switch OP is operated to switch the semiconductor switch element Q1 to the on state and the load L is energized, the charge command means CI ′ comprising a timer starts operating simultaneously. To do. When the semiconductor switch element Q1 continues to be in the on state, the charge command means CI ′ eventually issues a charge command after a predetermined time has elapsed. As a result, the charging unit CE is charged while the substantial ON state switching means SOC operates in the same manner as in the third embodiment and energizes the load L. For this reason, even if the semiconductor switch element Q1 is kept on for a long period of time, the semiconductor switch element Q1 can be reliably turned off when desired.

  FIG. 7 shows a fifth embodiment of the present invention. This embodiment is configured to suppress the occurrence of transient vibration due to kickback when the semiconductor switch element Q1 is turned off from the on state. That is, in the figure, symbol SVD is a semiconductor switch element voltage detection means, and SIC is a semiconductor switch element impedance control means.

  The semiconductor switch element voltage detection means SVD detects the voltage across the semiconductor switch element Q1. That is, when the semiconductor switch element Q1 is in the OFF state, a line voltage appears at both ends of the semiconductor switch element Q1, and this can be detected. Accordingly, the semiconductor switch element voltage detecting means SVD is configured so that the normal line voltage during normal operation and the line voltage when transient vibration due to the inductance accompanying the wiring length occurs in the line when the semiconductor switch element Q1 is turned off. Can be detected.

  The semiconductor switch element voltage impedance control means SIC controls the impedance of the semiconductor switch element Q1. For example, when the conductivity between both ends of the semiconductor switch element Q1 is changed by controlling the drive signal of the semiconductor switch element Q1, the impedance between both ends changes.

  Further, since the semiconductor switch element impedance control means SIC can reduce the impedance of the semiconductor switch element Q1 from the cut-off state to such an extent that it can act as a braking resistance for transient vibration, the impedance is controlled by performing the following procedure. Reduce or prevent the occurrence of vibration.

  That is, the semiconductor switch element impedance control means SIC first measures the normal line voltage in advance. In order to store the normal line voltage and read it out when desired, it is possible to provide a storage and reading unit comprising a microcomputer or an IC. Second, the line voltage, which is the voltage across the semiconductor switch element Q1 when the semiconductor switch element Q1 is turned off from the on state, is measured. Thirdly, the first and second line voltages are compared. As a result, when the second line voltage exceeds the first normal line voltage, the impedance of the semiconductor switch element Q1 is controlled from the cutoff state to the decreasing direction so that it can act as a braking resistor.

  Further, as a result of the comparison, when the second line voltage does not exceed the first normal line voltage, the impedance of the semiconductor switch element Q1 is maintained in the cutoff state. Furthermore, after controlling the impedance of the semiconductor switch element Q1, the transient vibration is suppressed or after the timing when the reduced transient vibration ends, the impedance of the semiconductor switch element Q1 is returned to the cutoff state.

  Further, the semiconductor switch element impedance control means SIC includes, for example, a control circuit CC having a storage / calculation function mainly including a microcomputer and a control signal generation function mainly including an oscillation circuit such as a monostable multivibrator, and a switch element Q3. And an impedance reduction circuit IDC having a series circuit of the resistor R3. More specifically, the control circuit CC operates upon receiving a control input of the detection output of the semiconductor switch element voltage detection means SVD, and when an overvoltage due to transient vibration is applied to both ends of the semiconductor switch element Q1, Arranged to generate a control signal for element Q3.

  In the impedance reduction circuit IDC, a series circuit of a switch element Q3 and a resistor R3 is connected in parallel to the operation switch OP. The switch element Q3 is composed of a transistor, and is turned on when the output of the control signal generation function of the monostable multivibrator is applied to the base thereof.

  Next, circuit operation will be described. When the operation switch OP in the on state is operated to switch it off, the semiconductor switch element Q1 is turned off, and a line voltage appears between both ends thereof, so that the semiconductor switch element voltage detection means SVD detects the voltage. Then, the line voltage in the normal state is measured and stored, and when the line voltage due to transient vibration starts to rise when the semiconductor switch element Q1 is turned off from the on state, the detection signal of the line voltage is sent to the semiconductor. A control input is made to the control circuit CC of the switch element impedance control means SIC.

  Therefore, when the semiconductor switch element Q1 is turned off, if kickback occurs due to the inductance due to the wiring length and the voltage across the semiconductor switch element Q1 starts to become higher than the normal circuit voltage, the control circuit CC causes the line to pass. Compare the voltage with the normal line voltage. As a result, when the occurrence of transient vibration is determined, the control circuit CC generates an impedance reduction signal.

  The impedance reduction signal is supplied to the base of the switch element Q3 of the impedance reduction circuit IDC, and the switch element Q3 is turned on. Thus, the voltage of the charging unit CE is divided by the resistor R3 and the resistor R2, and the divided voltage on the resistor R2 side is applied between the gate and the source of the semiconductor switch element Q1.

  Since the semiconductor switch element Q1 is preset so that the impedance becomes an effective value as a braking resistance against the transient vibration by the application of the gate voltage, the semiconductor switch element Q1 brakes the transient vibration. As a result, an overvoltage is not applied to the load L or even if it is applied.

  CC ... control circuit, CE ... charging unit, CH ... charging circuit, D1 ... diode, DR ... drive circuit, L ... load, l ... DC line, OP ... operation switch, Q ... semiconductor switch element, R1, R2 ... resistor , SW ... DC switch

Claims (4)

A semiconductor switch element connected in series with a load to a DC power supply;
A charging circuit connected in parallel to the semiconductor switch element;
A charging unit connected to the charging circuit and charged when the semiconductor switch element is off;
A drive circuit energized by the charging unit to turn on the semiconductor switch element;
An operation switch for controlling the action of the drive circuit on the semiconductor switch element;
The DC switch characterized by comprising.   An on-time charging means for charging the charging unit by applying a voltage to the charging circuit using the voltage drop while causing the semiconductor switch element to be substantially turned on while causing a voltage drop across the semiconductor switch element. The DC switch according to claim 1, further comprising:   3. The DC switch according to claim 2, further comprising charging section voltage detecting means for detecting the voltage of the charging section and operating the charging means when on when the detected voltage falls below a predetermined value. A semiconductor switch element voltage detecting means for detecting a voltage across the semiconductor switch element;
The normal line voltage when the semiconductor switch element is off is measured in advance by the semiconductor switch element voltage detection means, and the line voltage when the semiconductor switch element voltage detection means is turned off from the on state exceeds the normal line voltage. A semiconductor switch element impedance control means for controlling the impedance of the semiconductor switch element;
The DC switch according to any one of claims 1 to 3, further comprising:

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