JP2014233161A - Load controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small size load controller.SOLUTION: The load controller 1a includes: a diode bridge circuit 3 in which a first AC input terminal 31 is connected to a first source electrode S1 of a bidirectional switch element 2, and a second AC input terminal 32 is connected to a second source electrode S2 of the bidirectional switch element 2; a power supply circuit 4 that outputs a constant voltage across a plus terminal 33 of the diode bridge circuit 3 and a minus terminal 34 of the diode bridge circuit 3; a level convert circuit 5a that conducts between the plus terminal 33 and the minus terminal 34 with a predetermined impedance; and a gate drive circuit 6a that supplies the predetermined voltage from the power supply circuit 4 to the first gate electrode G1 and the second gate electrode G2. The gate drive circuit 6a supplies the predetermined voltage from the power supply circuit 4 to the first gate electrode G1 and the second gate electrode G2 when the control signal CS is high level. In the level convert circuit 5a, a bipolar transistor Q5 turns ON when the control signal CS is high level.

Description

  The present invention relates to a load control device.

  As a load control device, for example, a two-wire AC switch 100a configured as shown in FIG. 10 is known (Patent Document 1).

  The two-wire AC switch 100a is an AC switch that is connected and used between a commercial AC power source 101 and a load 102 such as a lighting fixture. The two-wire AC switch 100a includes a bidirectional switch element 103, a full-wave rectifier 104, a power supply circuit 105, a drive circuit (a first gate drive circuit 107 and a second gate drive circuit 108), and a control circuit. 106.

  The bidirectional switch element 103 is a double-gate switch element made of a group III nitride semiconductor that has a configuration in which a current flows in both directions and turns the current flow on or off. The bidirectional switch element 103 includes a switch terminal S11 and a switch terminal S12 to be switched (conducting / non-conducting), a control terminal G11 connected to two gates for controlling on and off of a current flow, and It has a control terminal G12 and a substrate terminal SUB electrically connected to the substrate on which the bidirectional switch element 103 is formed. Here, the commercial AC power supply 101, the load 102, and the bidirectional switch element 103 (its switch terminal S11 and switch terminal S12) are connected in series so as to form a closed circuit.

  The full-wave rectifier 104 is a bridge diode or the like that is connected between the switch terminal S11 and the switch terminal S12 and that full-wave rectifies the AC power supplied from the commercial AC power supply 101.

  The power supply circuit 105 is a circuit that smoothes the voltage after full-wave rectification output from the full-wave rectifier 104 and supplies DC power. Power necessary for the first gate drive circuit 107, the second gate drive circuit 108, and the control circuit 106 is supplied from the power supply circuit 105.

  When supplying power from the commercial AC power supply 101 to the load 102, the control circuit 106 turns on the bidirectional switch element 103. In this case, in the control circuit 106, the first gate drive circuit 107 and the second gate drive circuit 108 are connected to the control terminal G11 and the control terminal G12 of the bidirectional switch element 103, respectively. The first gate circuit 107 and the second gate drive circuit 108 are controlled so as to output a control signal having a voltage higher than the threshold voltage of the gate corresponding to G12. As a result, the control circuit 106 turns on the bidirectional switch element 103.

  On the other hand, the control circuit 106 turns off the bidirectional switch element 103 when the supply of power from the commercial AC power supply 101 to the load 102 is interrupted. In this case, in the control circuit 106, the first gate drive circuit 107 and the second gate drive circuit 108 are connected to the control terminal G11 and the control terminal G12 of the bidirectional switch element 103, respectively. The first gate drive circuit 107 and the second gate drive circuit 108 are controlled so as to output a control signal having a voltage lower than the threshold voltage of the gate corresponding to G12. As a result, the control circuit 106 turns off the bidirectional switch element 103.

  The control circuit 106 is a circuit that controls the first gate driving circuit 107 and the second gate driving circuit 108 as described above.

  More specifically, a signal indicating whether or not power is supplied from the commercial AC power supply 101 to the load 102 is transmitted from the external setting unit 109 to the control circuit 106. Based on the transmitted signal, the control circuit 106 outputs a control signal to the input terminal SIN1 of the first gate drive circuit 107 and the input terminal SIN2 of the second gate drive circuit 108.

  The first gate drive circuit 107 and the second gate drive circuit 108 control the output terminals OUT1 and OUT2 from the output terminals OUT1 and OUT2 to the control terminals G11 and G12 of the bidirectional switch element 103, respectively, based on the control signal from the control circuit 106. By outputting a signal, the switching operation of the bidirectional switch element 103 is controlled.

JP 2011-103729 A

  In Patent Document 1, specific circuit configurations of the first gate driving circuit 107 and the second gate driving circuit 108 in the two-wire AC switch 100a are not specified.

  By the way, in the load control device, further downsizing is desired. However, when the gate driving circuit has a level shift circuit for changing the voltage level, further downsizing tends to be difficult. In the load control device, when the gate drive circuit is configured to drive the bidirectional switch element with a transformer, miniaturization tends to be difficult.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a load control device that can be reduced in size.

  The load control device of the present invention is a load control device including a bidirectional switch element provided in a power supply path from an AC power supply to a load, wherein the bidirectional switch element includes a first gate electrode, a second gate electrode, A first source electrode and a second source electrode, and applying a predetermined voltage between the first gate electrode and the first source electrode and between the second gate electrode and the second source electrode. The first source electrode and the second source electrode are turned on, and a first AC input terminal is connected to the first source electrode, and a second AC input terminal is connected to the second source electrode. A connected diode bridge circuit, a power supply circuit for making the output voltage between the plus terminal of the diode bridge circuit and the minus terminal of the diode bridge circuit constant, and the plus terminal; A level conversion circuit that conducts between the negative terminal with a predetermined impedance, and the predetermined switch for turning on the bidirectional switch from the power supply circuit to the first gate electrode and the second gate electrode of the bidirectional switch element. A gate driving circuit that supplies a voltage or a predetermined current, and the gate driving circuit is configured to receive a control signal for controlling on / off of the bidirectional switch element, and the control signal The predetermined voltage or the predetermined current is supplied from the power supply circuit to the first gate electrode and the second gate electrode when the level is high, the level conversion circuit includes a bipolar transistor, and a collector terminal of the bipolar transistor is Connected to the positive terminal, the emitter terminal is connected to the negative terminal, the base terminal, It is configured to control signal is input, the control signal and wherein said that the bipolar transistor is turned on when the high level.

  In this load control device, it is preferable that the level conversion circuit includes a first resistor connected between an emitter terminal of the bipolar transistor and the negative terminal.

  In the load control device, the gate driving circuit applies a current larger than the predetermined current to the first gate electrode and the second gate electrode for a specified time when the control signal changes from a low level to a high level. It is preferable to supply.

  In this load control device, the gate drive circuit includes an npn transistor, and a current mirror circuit having a first pnp transistor, a second pnp transistor, and a second resistor, and the npn transistor has an emitter terminal as the emitter terminal. The first pnp transistor is connected to the output terminal on the high potential side of the power supply circuit, connected to the negative terminal and grounded, and the control signal is input to the base terminal. A terminal is connected between the collector terminal, the second pnp transistor has an emitter terminal connected to the output terminal of the power supply circuit, and a collector terminal connected to the first gate electrode via a first diode. And connected to the second gate electrode through a second diode, and the second resistor is connected to the np A capacitor is connected between the collector terminal of the transistor and the collector terminal of the first pnp transistor, and a capacitor is connected in parallel between both ends of the second resistor, and the specified time includes the second resistor and the capacitor. It is preferable to be determined by the time constant of the parallel circuit.

  In this load control device, it is preferable that the gate driving circuit includes two current sources corresponding to the first gate electrode and the second gate electrode on a one-to-one basis.

  The load control device according to the present invention can be downsized.

FIG. 1 is a circuit diagram of the load control apparatus according to the first embodiment. FIG. 2 is an operation explanatory diagram of the load control device according to the first embodiment. FIG. 3 is an operation explanatory diagram of the load control device according to the first embodiment. FIG. 4 is a circuit diagram of a modification of the load control device according to the first embodiment. FIG. 5 is a circuit diagram of the load control apparatus according to the second embodiment. FIG. 6 is an operation explanatory diagram of the load control device of the second embodiment. FIG. 7 is a schematic operation explanatory diagram of the load control device according to the second embodiment. FIG. 8 is a circuit diagram of a comparative example of the load control device of the second embodiment. FIG. 9 is a circuit diagram of the load control device according to the third embodiment. FIG. 10 is a circuit diagram of a conventional two-wire AC switch.

(Embodiment 1)
Below, the load control apparatus 1a of this embodiment is demonstrated based on FIG.

  The load control device 1 a is a load control device including a bidirectional switch element 2 provided in a power supply path from the AC power supply 8 to the load 9.

  The bidirectional switch element 2 includes a first gate electrode G1, a second gate electrode G2, a first source electrode S1, and a second source electrode S2. A second switch element 2 is provided between the first gate electrode G1 and the first source electrode S1. By applying a predetermined voltage between the gate electrode G2 and the second source electrode S2, the first source electrode S1 and the second source electrode S2 are turned on so as to be conductive.

  The load control device 1a includes a diode bridge circuit 3 in which a first AC input terminal 31 is connected to the first source electrode S1 and a second AC input terminal 32 is connected to the second source electrode S2, and a diode bridge circuit 3 A power supply circuit 4 that makes the output voltage between the plus terminal 33 and the minus terminal 34 of the diode bridge circuit 3 constant, a level conversion circuit 5a that makes the plus terminal 33 and the minus terminal 34 conductive with a predetermined impedance, A gate drive circuit 6a for supplying the predetermined voltage from the power supply circuit 4 to the first gate electrode G1 and the second gate electrode G2 of the bidirectional switch element 2;

  The gate drive circuit 6a is configured to receive a control signal CS for controlling on / off of the bidirectional switch element 2, and when the control signal CS is at a high level, the power supply circuit 4 supplies the first gate electrode G1. The predetermined voltage is supplied to the second gate electrode G2. The level conversion circuit 5a includes a bipolar transistor Q5. The collector terminal of the bipolar transistor Q5 is connected to the plus terminal 33, the emitter terminal is connected to the minus terminal 34, and the control signal CS is input to the base terminal. When the control signal CS is at a high level, the bipolar transistor Q5 is turned on. Thereby, the load control device 1a can be downsized.

  Each component of the load control device 1a will be described in detail below.

  The load control device 1a is used by connecting a series circuit of an AC power supply 8 and a load 9 between the first source electrode S1 and the second source electrode S2 of the bidirectional switch element 2. For this reason, the load control device 1a includes a first main terminal 21 and a second main terminal 22 to which the first source electrode S1 and the second source electrode S2 of the bidirectional switch element 2 are connected, respectively. A series circuit of the AC power supply 8 and the load 9 can be connected between the terminal 21 and the second main terminal 22.

  In the load control device 1 a, the bidirectional switch element 2 is connected in series between the AC power supply 8 and the load 9 between the AC power supply 8 and the load 9. Thereby, the load control apparatus 1a can control on and off of the load 9. The AC power supply 8 is a commercial power supply, for example. The load 9 is, for example, an illumination load.

  The bidirectional switch element 2 can take two stable states of ON (ON state) and OFF (OFF state) in any bias direction between the first source electrode S1 and the second source electrode S2. AC switch element that can be used. The bidirectional switch element 2 includes a normally-off type heterojunction field effect transistor (HFET) including a first gate electrode G1, a second gate electrode G2, a first source electrode S1, and a second source electrode S2. ). In this case, in the bidirectional switch element 2, the first source electrode S1 constitutes the first main electrode, and the second source electrode S2 constitutes the second main electrode.

  As the HFET, for example, an AlGaN / GaN HFET can be employed. In the bidirectional switch element 2, the first source electrode S 1 is connected to the first main terminal 21 and the second source electrode S 2 is connected to the second main terminal 22.

  As the bidirectional switch element 2, the bidirectional switch element 103 in the two-wire AC switch of FIG. 10 can also be adopted.

  The bidirectional switch element 2 may be configured by connecting two metal oxide semiconductor field effect transistors (MOSFETs) in reverse series. The bidirectional switch element 2 may employ, for example, an enhancement type (normally off type) n-channel MOSFET as each MOSFET and connect the drain electrodes of both MOSFETs. Each MOSFET includes a built-in diode (also called “body diode” or “parasitic diode”). Each built-in diode functions as a rectifying diode.

  For example, a Si-based MOSFET can be employed as the MOSFET. The MOSFET is not limited to a Si-based MOSFET, and, for example, a SiC-based MOSFET, a GaN-based MOSFET, or the like can be employed.

  The diode bridge circuit 3 is a full-wave rectifier circuit in which four diodes D01, D02, D03, and D04 are bridge-connected as shown in FIGS.

  The diode bridge circuit 3 bridges four diodes D01, D02, D03, and D04 by connecting in parallel a series circuit of two diodes D01 and D02 and a series circuit of two diodes D03 and D04. It is connected. In the diode bridge circuit 3, a connection point between the two diodes D01 and D02 forms a first AC input terminal 31, and a connection point between the two diodes D03 and D04 forms a second AC input terminal 32. In the diode bridge circuit 3, the connection point between the two diodes D02 and D04 constitutes a plus terminal 33, and the connection point between the two diodes D01 and D03 constitutes a minus terminal 34.

  In short, the diode bridge circuit 3 includes a first AC input terminal 31, a second AC input terminal 32, a plus terminal 33, and a minus terminal 34. In the diode bridge circuit 3, the first AC input terminal 31 is connected to the first source electrode S 1 via the first main terminal 21, and the second AC input terminal 32 is connected to the second source electrode S 2 via the second main terminal 22. It is connected to the.

  The diode bridge circuit 3 has a function of full-wave rectifying the AC voltage from the AC power supply 8 connected between the first source electrode S1 and the second source electrode S2 of the bidirectional switch element 2 into a DC voltage. In short, the diode bridge circuit 3 is configured to output a DC voltage obtained by full-wave rectifying the AC voltage from the AC power supply 8 between the plus terminal 33 and the minus terminal 34.

  In the load control device 1 a, the power supply circuit 4 is connected between the plus terminal 33 and the minus terminal 34 of the diode bridge circuit 3.

  The power supply circuit 4 is a constant voltage circuit that converts the output voltage of the diode bridge circuit 3 into a predetermined DC voltage.

  The power supply circuit 4 is a constant voltage circuit including an npn transistor Q4, a Zener diode ZD4, a resistor R4, and a smoothing capacitor C4. This constant voltage circuit is a series type constant voltage circuit in which an npn transistor 4 is interposed between a plus terminal 33 of the diode bridge circuit 3 and an output terminal on the high potential side of the power supply circuit 4.

  In the power supply circuit 4, a series circuit of a resistor R 4 and a Zener diode ZD 4 is connected between a plus terminal 33 and a minus terminal 34 of the diode bridge circuit 3. In the power supply circuit 4, one end of the resistor R 4 is connected to the plus terminal 33 of the diode bridge circuit 3, the other end of the resistor R 4 is connected to the cathode of the Zener diode ZD 4, and the anode of the Zener diode ZD 4 is connected to the diode bridge circuit 3. Is connected to the minus terminal 34. In the power supply circuit 4, the collector terminal of the npn transistor Q4 is connected to one end of the resistor R4, and the base terminal is connected to the connection point between the resistor R4 and the Zener diode ZD4. In the power supply circuit 4, a smoothing capacitor C4 is connected in parallel between the emitter terminal of the npn transistor Q4 and the anode of the Zener diode ZD4. The smoothing capacitor C4 is composed of a polar capacitor such as an aluminum electrolytic capacitor.

  The output voltage VDD of the power supply circuit 4 is the voltage across the smoothing capacitor C4. The power supply circuit 4 is configured so that the output voltage VDD is kept constant. The output voltage VDD of the power supply circuit 4 is a value obtained by subtracting the voltage between the base terminal and the emitter terminal of the npn transistor Q4 from the Zener voltage of the Zener diode ZD4. The circuit configuration of the power supply circuit 4 is an example, and the circuit configuration is not particularly limited as long as it is a constant voltage circuit.

  The load control device 1a includes a terminal 7 to which a control signal CS generated by a control circuit (not shown) is input. The control circuit is a circuit that controls the gate driving circuit 6a. The control circuit outputs a control signal CS to the terminal 7. The terminal 7 may be an output terminal that outputs a control signal CS in the control circuit. Further, the control circuit can be constituted by, for example, a microcomputer equipped with an appropriate program.

  The control circuit turns on the bidirectional switch element 2 when power is supplied from the AC power supply 8 to the load 9. In this case, in the control circuit, the gate drive circuit 6a is arranged between the first gate electrode G1 and the first source electrode S1 with respect to the first gate electrode G1 and the second gate electrode G2 of the bidirectional switch element 2. The gate driving circuit 6a is controlled so as to output the predetermined voltage higher than the first gate threshold voltage and the second gate threshold voltage between the second gate electrode G2 and the second source electrode S2. As a result, the control circuit turns on the bidirectional switch element 2. The bidirectional switch element 2 preferably has the same first gate threshold voltage and second gate threshold voltage.

  The control circuit turns off the bidirectional switch element 2 when the power supply from the AC power supply 8 to the load 9 is cut off. In this case, the control circuit is configured such that the gate drive circuit 6a is lower than the first gate threshold voltage and the second gate threshold voltage with respect to the first gate electrode G1 and the second gate electrode G2 of the bidirectional switch element 2. To control the gate drive circuit 6a. Thereby, the control circuit turns off the bidirectional switch element 2.

  The control circuit receives a signal instructing whether to supply power from the AC power supply 8 to the load 9 from an external setting unit (not shown). The control circuit outputs a control signal CS based on the signal transmitted from the setting unit. Specifically, the control circuit sets the control signal CS to a high level when the signal for instructing the supply of power from the AC power supply 8 to the load 9 is transmitted from the setting unit. When a signal instructing not to supply power to the load 9 (cut off the power supply from the AC power supply 8 to the load 9) is transmitted, the control signal CS is set to a low level. The gate drive circuit 6a controls the switching operation of the bidirectional switch element 2 based on the control signal CS.

  The gate drive circuit 6a is configured to have a function of supplying the predetermined voltage for turning on the bidirectional switch element 2 from the power supply circuit 4 to the first gate electrode G1 and the second gate electrode G2 of the bidirectional switch element 2. Has been.

  The gate drive circuit 6a includes a MOSFET 61, an inverter 62, a first diode D1, a second diode D2, and two resistors R61 and R62.

  The gate drive circuit 6 a employs an enhancement type p-channel MOSFET as the MOSFET 61. The MOSFET 61 has a source terminal connected to the output terminal on the high potential side of the power supply circuit 4, a drain terminal connected to a connection point between the anodes of the first diode D1 and the second diode D2, and a gate terminal The output terminal of the inverter 62 is connected. The cathodes of the first diode D1 and the second diode D2 are connected to the first gate electrode G1 and the second gate electrode G2, respectively. The inverter 62 has an input terminal connected to the terminal 7. In short, the inverter 62 inverts the control signal CS from the terminal 7 and inputs it to the gate terminal of the MOSFET 61. Therefore, in the gate drive circuit 6a, when the control signal CS is at a low level, the output of the inverter 62 is at a high level and the MOSFET 61 is turned off. On the other hand, in the gate drive circuit 6a, when the control signal CS is at a high level, the output of the inverter 62 is at a low level and the MOSFET 61 is turned on.

  The level conversion circuit 5 a is provided between the diode bridge circuit 3 and the power supply circuit 4. The level conversion circuit 5a is configured to have a function of conducting between the positive terminal 33 and the negative terminal 34 of the diode bridge circuit 3 with the predetermined impedance. The level conversion circuit 5a includes a bipolar transistor Q5. The collector terminal of the bipolar transistor Q5 is connected to the plus terminal 33, the emitter terminal is connected to the minus terminal 34, and the control signal CS is input to the base terminal. Has been. The level conversion circuit 5a includes a resistor R51, and the base terminal of the bipolar transistor Q5 is connected to the terminal 7 via the resistor R51.

  In the level conversion circuit 5a, when the control signal CS is at a low level, the bipolar transistor Q5 is turned off, and the plus terminal 33 and the minus terminal 34 of the diode bridge circuit 3 are made non-conductive.

  In the level conversion circuit 5a, when the control signal CS is at a high level, the bipolar transistor Q5 is turned on, and the positive terminal 33 and the negative terminal 34 of the diode bridge circuit 3 are made conductive with a predetermined impedance. Here, the predetermined impedance is the on-resistance of the bipolar transistor Q5 and is substantially zero.

  2 and 3 are operation explanatory diagrams of the load control device 1a when the control signal CS is at a high level.

  When the control signal CS is at a high level, the load control device 1a is supplied from the smoothing capacitor C4 of the power supply circuit 4 so that the bidirectional switch element 2 is maintained in an on state and power is supplied from the AC power supply 8 to the load 9. A current path for supplying a gate current to the first gate electrode G1 and the second gate electrode G2 is formed. 2 and 3, this current path is indicated by a one-dot chain line.

  2 shows a current path (hereinafter referred to as “first current”) formed in a period in which the polarity of the AC voltage of the AC power supply 8 is indicated by an arrow B1 in FIG. 2 (hereinafter, this direction is referred to as “positive polarity”). The route is referred to as an alternate long and short dash line. The first current path is the smoothing capacitor C4 of the power supply circuit 4 → the MOSFET 61 of the gate drive circuit 6a → the first diode D1 and the second diode D2 of the gate drive circuit 6a → the second source electrode S2 of the bidirectional switch element 2 → the diode bridge. This is a path of the diode D04 of the circuit 3 → the bipolar transistor Q5 of the level conversion circuit 5 → the smoothing capacitor C4.

  3 shows a current path (hereinafter referred to as “second current”) formed during a period in which the polarity of the AC voltage of the AC power supply 8 is indicated by an arrow B2 in FIG. 2 (hereinafter, this direction is referred to as “negative polarity”). The route is referred to as an alternate long and short dash line. The second current path consists of the smoothing capacitor C4 of the power supply circuit 4 → the MOSFET 61 of the gate drive circuit 6a → the first diode D1 and the second diode D2 of the gate drive circuit 6a → the first source electrode S1 of the bidirectional switch element 2 → the diode bridge. This is a path of the diode D02 of the circuit 3 → the bipolar transistor Q5 of the level conversion circuit 5 → the smoothing capacitor C4.

  In short, in the load control device 1a, the first current path and the second current path for supplying a gate current from the smoothing capacitor C4 of the power supply circuit 4 to both the first gate electrode G1 and the second gate electrode G2 of the bidirectional switch element 2. A part of each can be formed by the level conversion circuit 5. Therefore, the load control device 1a includes the diode bridge circuit 3 without providing the gate drive circuit 6a with a level shift circuit for generating potentials based on the first source electrode S1 and the second source electrode S2, respectively. The bidirectional switch element 2 can be driven by a voltage with reference to the negative terminal 34 of the negative terminal 34. Thereby, the load control device 1a can be downsized.

  Below, the load control apparatus 1b of the modification of the load control apparatus 1a of this embodiment is demonstrated based on FIG. The load control device 1b of the modification is different from the load control device 1a of the first embodiment in that a level conversion circuit 5b is provided instead of the level conversion circuit 5a in the load control device 1a of the first embodiment. In addition, about the component similar to the load control apparatus 1a of Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The level conversion circuit 5b has substantially the same circuit configuration as the level conversion circuit 5a, and includes a first resistor R52 connected between the emitter terminal of the bipolar transistor Q5 and the negative terminal 34 of the diode bridge circuit 3. Is different.

  In the level conversion circuit 5b, when the control signal CS is at a high level, the bipolar transistor Q5 is turned on, and the positive terminal 33 and the negative terminal 34 of the diode bridge circuit 3 are made conductive with the predetermined impedance. Here, the predetermined impedance is a combined resistance value of the ON resistance of the bipolar transistor Q5 and the resistance value of the first resistor R52. Since the on-resistance value of the bipolar transistor Q5 is substantially zero, the predetermined impedance can be regarded as the resistance value of the first resistor R52.

  In the load control device 1b, since the level conversion circuit 5b includes the first resistor R52, the current flowing through the level conversion circuit 5b can be made constant, and the first gate electrode of the bidirectional switch element 2 can be made constant. It becomes possible to limit the gate current flowing through each of G1 and the second gate electrode G2. Therefore, in the load control device 1b, the first resistor R52 functions as a current limiting resistor, and the current consumption of the gate drive circuit 6a can be reduced compared to the load control device 1a.

(Embodiment 2)
Below, the load control apparatus 1c of this embodiment is demonstrated based on FIG. In addition, about the component similar to the load control apparatus 1a of Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  The load control device 1c of the present embodiment is different in that a gate drive circuit 6c is provided instead of the gate drive circuit 6a of the load control device 1a of the first embodiment.

  The gate drive circuit 6c supplies a predetermined current for turning on the bidirectional switch element 2 from the power supply circuit 4 to the first gate electrode G1 and the second gate electrode G2 of the bidirectional switch element 2.

  As shown in FIG. 6, when the control signal CS changes from a low level to a high level, the gate drive circuit 6c generates a current larger than the predetermined current as the gate current for the specified time T1 and the first gate electrode G1 The two gate electrodes G2 can be supplied. The gate drive circuit 6c supplies a current larger than the predetermined current to the first gate electrode G1 and the second gate electrode G2 for a specified time T1, and then continues to the predetermined signal until the control signal CS changes from a high level to a low level. The current continues to be supplied to the first gate electrode G1 and the second gate electrode G2.

  The gate driving circuit 6c includes an npn transistor Q1, a current mirror circuit 60c having a first pnp transistor Q2, a second pnp transistor Q3, and a second resistor R1.

  The npn transistor Q1 is configured such that the emitter terminal is connected to the minus terminal 34 of the diode bridge circuit 3 and grounded, and the control signal CS is input to the base terminal. The base terminal of the npn transistor Q1 is preferably connected to the terminal 7 via the resistor R63. In short, the gate drive circuit 6c preferably includes a resistor R63.

  The first pnp transistor Q2 has an emitter terminal connected to the output terminal on the high potential side of the power supply circuit 4, and a base terminal and a collector terminal connected to each other.

  The second pnp transistor Q3 has an emitter terminal connected to the output terminal on the high potential side of the power supply circuit 4, a collector terminal connected to the first gate electrode G1 via the first diode D1, and a second It is connected to the second gate electrode G2 via the diode D2.

  The second resistor R1 is connected between the collector terminal of the npn transistor Q1 and the collector terminal of the first pnp transistor Q2. The gate drive circuit 6c includes a capacitor C1 connected in parallel between both ends of the second resistor R1. Thus, the specified time T1 is determined by the time constant of the parallel circuit of the second resistor R1 and the capacitor C1.

  The current mirror circuit 60c is a circuit that allows a current equal to the current flowing through the second resistor R1 to flow through the second pnp transistor Q3. In the current mirror circuit 60c, the second pnp transistor Q3 constitutes an output transistor.

  Here, in the load control device having a basic configuration in which the gate drive circuit 6c does not include the capacitor C1, the current mirror circuit 60c forms a constant current circuit (also referred to as “constant current source”), and the first gate electrode G1. A constant gate current is output to each of the second gate electrode G2. An operation example of the bidirectional switch element 2 of the load control device having the basic configuration will be described based on equivalent circuits shown in FIGS. 7A and 7B are operation examples when the polarity of the AC voltage of the AC power supply 8 is positive. 7A and 7B, “+ V” is the potential (> 0) of the first main terminal 21 (see FIG. 5), and “0V” is the second main terminal 22 (see FIG. 5). Potential. 7A and 7B, the current mirror circuit 60c is represented by a graphic symbol of a constant current source. 7A and 7B, the bidirectional switch element 2 includes a first transistor Tr1 including a first gate electrode G1 and a first source electrode S1, a second gate electrode G2, and a second source electrode. It is represented by a circuit in which the drain electrodes of the transistor Tr2 having S2 are connected to each other.

  FIG. 7A is an equivalent circuit of a main part immediately after the control signal CS changes from the low level to the high level. When the supply of the gate current from the constant current source 60c of the gate drive circuit 6c to the bidirectional switch element 2 is started, the load controller having the basic configuration starts to connect the gate electrode G2 of the second transistor Tr2 on the low potential side. A gate current flows through the two diodes D2, and the second transistor Tr2 is turned on. On the other hand, in the load control device having the basic configuration, since the first diode D1 connected to the gate electrode G1 of the first transistor Tr1 is reverse-biased, no gate current flows to the first transistor Tr1.

  FIG. 7B is an equivalent circuit of the main part immediately after the second transistor Tr2 is turned on. In the load control device of the basic configuration, when the second transistor Tr2 is turned on, the first diode D2 is forward biased, the first transistor Tr1 on the high potential side is also turned on, and the bidirectional switch element 2 is turned on.

  On the other hand, in the load control device 1c of the present embodiment, when the control signal CS changes from the low level to the high level, a current larger than the predetermined current as the gate current is set for the specified time T1 for the first gate electrode G1. And it is comprised so that it can supply to 2nd gate electrode G2. As a result, in the load control device 1c, the current in the transient state is increased until the bidirectional switch element 2 is turned on so that the bidirectional switch element 2 is turned on more quickly and reliably. By keeping the current at constant, the current consumption can be reduced. The period of the transient state is usually about several ns to several μs. Therefore, the load control device 1c can reduce the current consumption if the high-level period of the control signal CS is sufficiently longer than the transient period. Therefore, the specified period T1 may be set in a range of about 2 to 10 times the period of the transient state, for example.

  FIG. 8 shows a modified gate drive circuit in the load control device 1c of the present embodiment. This gate drive circuit is different from the gate drive circuit 6c in that it includes a third resistor R2 and an npn transistor Q8 instead of providing the capacitor C1 of the gate drive circuit 6c. The third resistor R2 has one end connected to the connection point between the collector terminal of the first pnp transistor Q2 and the second resistor R1, and the other end connected to the collector terminal of the npn transistor Q8. The npn transistor Q8 has an emitter terminal connected to the minus terminal 34 of the diode bridge circuit 3, and a base terminal connected to the terminal 7 to which a control signal CS (hereinafter also referred to as “first control signal CS”) is input. It is connected to a terminal 8 provided separately. The terminal 8 receives a second control signal CS2 for turning on / off the npn transistor Q8. The second control signal CS2 rises from the low level to the high level in synchronization with the first control signal CS and rises, and maintains the high level only for the specified period T1, and then rises to the low level. It is a signal that goes down. The second control signal CS2 input to the terminal 8 is preferably generated and output by the control circuit, for example.

  In the configuration of FIG. 8, a current larger than the predetermined current when no current flows through the third resistor R2 can be passed only for a specified time T1 when the second resistor R1 and the third resistor R2 are connected in parallel. . Therefore, in the gate drive circuit according to the modified example, the current in the transient state is increased until the bidirectional switch element 2 is turned on so that the bidirectional switch element 2 is turned on more quickly and reliably. By keeping the current in the state constant, the current consumption can be reduced.

  In the load control device 1c of the present embodiment, by providing the gate drive circuit 6c, the specified time T1 is determined by the time constant of the parallel circuit of the second resistor R1 and the capacitor C1, and thus the modified gate drive circuit is adopted. The circuit configuration can be simplified as compared with the case of doing so.

  The load control device 1c according to the present embodiment includes, for example, a level conversion circuit 5b in a load control device 1b (see FIG. 4) as a modification of the load control device 1a according to the first embodiment, instead of the level conversion circuit 5a. May be.

(Embodiment 3)
Below, the load control apparatus 1d of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected about the component similar to the load control apparatus 1c of Embodiment 2, and description is abbreviate | omitted suitably.

  The load control device 1d of the present embodiment is different in that a gate drive circuit 6d is provided instead of the gate drive circuit 6c of the load control device 1c of the second embodiment.

  The gate drive circuit 6d includes a current mirror circuit 60d in which a second pnp transistor Q31 and a third pnp transistor Q32 are provided instead of the second pnp transistor Q3. The current mirror circuit 60d connects the base terminal and the collector terminal of the first pnp transistor Q21. In the gate drive circuit 6d, the collector terminal of the second pnp transistor Q31 is connected to the anode of the second diode D2, and the collector terminal of the third pnp transistor Q32 is connected to the anode of the first diode D1.

  The gate drive circuit 6d is designed so that the first pnp transistor Q21, the second pnp transistor Q31, and the third pnp transistor Q32 have the same characteristics. As a result, the gate drive circuit 6d can pass a current having the same magnitude as the current flowing through the first pnp transistor Q21 to the second pnp transistor Q31 and the third pnp transistor Q32. Therefore, in the gate drive circuit 6d, each of the second pnp transistor Q31 and the third pnp transistor Q32 constitutes a current source. That is, the gate drive circuit 6d includes two current sources that correspond one-to-one to the first gate electrode G1 and the second gate electrode G2.

  By the way, the characteristics of the bidirectional switch element 2 include, for example, the first transistor Tr1 (see FIG. 7A) including the first gate electrode G1 and the first source electrode S1, the second gate electrode G2, and the second source. Variations may occur due to variations in transistor characteristics with the second transistor Tr2 (see FIG. 7A) including the electrode S2.

  On the other hand, in the load control device 1d, since the gate drive circuit 6d includes two current sources corresponding to the first gate electrode G1 and the second gate electrode G2, respectively, the bidirectional switch element 2 It is possible to cancel the variation in driving performance caused by the variation in characteristics.

  The load control device 1d of the present embodiment includes, for example, a level conversion circuit 5b in a load control device 1b (see FIG. 4) of a modification of the load control device 1a of the first embodiment, instead of the level conversion circuit 5a. May be.

  As mentioned above, although the structure of this invention was demonstrated based on Embodiment 1-3, this invention is not restricted to the structure of Embodiment 1-3, for example, For example, partial structure of Embodiment 1-3 These may be combined as appropriate. In addition, the present invention can be modified as appropriate without departing from the scope of its technical idea.

1a, 1b, 1c, 1d Load control device 2 Bidirectional switch element 3 Diode bridge circuit 4 Power supply circuit 5a, 5b Level conversion circuit 6a, 6c, 6d Gate drive circuit 31 1st alternating current input terminal 32 2nd alternating current input terminal 33 plus Terminal 34 Negative terminal C1 Capacitor CS Control signal G1 First gate electrode G2 Second gate electrode S1 First source electrode S2 Second source electrode Q1 npn transistor Q2 First pnp transistor Q3 Second pnp transistor Q5 Bipolar transistor R1 Second Resistor R52 1st resistor

Claims (5)

A load control device including a bidirectional switch element provided in a power supply path from an AC power supply to a load,
The bidirectional switch element includes a first gate electrode, a second gate electrode, a first source electrode, and a second source electrode, and the second gate electrode is disposed between the first gate electrode and the first source electrode. The first source electrode and the second source electrode are turned on by applying a predetermined voltage between the second source electrode and the second source electrode.
A diode bridge circuit having a first AC input terminal connected to the first source electrode and a second AC input terminal connected to the second source electrode; a positive terminal of the diode bridge circuit; and a negative terminal of the diode bridge circuit; A power supply circuit that makes the output voltage between the positive terminal and the negative terminal conductive with a predetermined impedance; and a first gate electrode of the bidirectional switch element from the power supply circuit And a gate driving circuit for supplying the predetermined voltage or the predetermined current for turning on the bidirectional switch to the second gate electrode,
The gate driving circuit is configured to receive a control signal for controlling on / off of the bidirectional switch element, and when the control signal is at a high level, the power supply circuit supplies the first gate electrode and Supplying the predetermined voltage or the predetermined current to the second gate electrode;
The level conversion circuit includes a bipolar transistor, and is configured such that a collector terminal of the bipolar transistor is connected to the plus terminal, an emitter terminal is connected to the minus terminal, and the control signal is input to a base terminal. The bipolar transistor is turned on when the control signal is at a high level.   2. The load control device according to claim 1, wherein the level conversion circuit includes a first resistor connected between an emitter terminal of the bipolar transistor and the negative terminal.   The gate driving circuit supplies a current larger than the predetermined current to the first gate electrode and the second gate electrode for a specified time when the control signal changes from a low level to a high level. The load control device according to claim 1 or 2. The gate drive circuit includes an npn transistor, a current mirror circuit having a first pnp transistor, a second pnp transistor, and a second resistor,
The npn transistor is configured such that an emitter terminal is connected to the minus terminal and grounded, and the control signal is input to a base terminal.
In the first pnp transistor, an emitter terminal is connected to an output terminal on the high potential side of the power supply circuit, and a base terminal and a collector terminal are connected,
The second pnp transistor has an emitter terminal connected to the output terminal of the power supply circuit, a collector terminal connected to the first gate electrode via a first diode, and the second diode via the second diode. Connected to the second gate electrode;
The second resistor is connected between a collector terminal of the npn transistor and a collector terminal of the first pnp transistor;
A capacitor is connected in parallel between both ends of the second resistor;
4. The load control device according to claim 3, wherein the specified time is determined by a time constant of a parallel circuit of the second resistor and the capacitor.   4. The load according to claim 1, wherein the gate driving circuit includes two current sources corresponding to the first gate electrode and the second gate electrode on a one-to-one basis. 5. Control device.

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