JP2011172298A - Gate drive technique for bidirectional switch, and power converter that uses the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-loss gate drive technique by preventing overcurrent and overvoltage incidences in various components in unintended transient periods, when a bidirectional device is applied as a semiconductor device applied to an inverter or the like. <P>SOLUTION: There is provided the gate drive technique that controls a bidirectional switch 1 which is equipped with a first gate terminal 2, a second gate terminal 3, a drain terminal 4, and a source terminal 5, and possesses four operating modes in which the first gate terminal 2 and second gate terminal 3 are variously ON and/or OFF. The gate drive technique uses a control module for controlling so that the bidirectional switch 1 does not shift directly when shifting from a bidirectionally OFF state to a bidirectional ON state. The gate drive technique operates the bidirectional switch 1 mainly in an operation mode without bidirectional intervention of a diode, and can operate the bidirectional switch 1 with intervention of the diode in the transient periods, thereby obtaining effects of preventing overcurrent and overvoltage incidences in the various components. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gate driving method for a bidirectional switch having four states by controlling a gate signal.

  In recent years, the spread of electronic devices has tended to expand further. At the same time, however, the power consumption of electronic devices has increased, and global warming has occurred, which is recognized as a social problem. Due to this social background, there is an increasing demand for low power consumption of electronic devices. Standby power, such as actuators for realizing the main functions of the main power supply circuit or electronic devices, and power for operation Any power consumption is expected to be reduced by technological innovation.

  Conventionally, as a technology for reducing the power consumption of this type, there is a power conversion circuit using a bidirectional switch as a new semiconductor device, depending on a voltage to be used. Proposed. Hereinafter, a method for driving the bidirectional switch will be described with reference to FIG. 12 as an example.

  FIG. 12 shows driving of the gate electrode when the potential of the main electrode corresponding to the low voltage side is lower than the potential of the main electrode corresponding to the high voltage side, and the initial state is that the element is non-conductive and the gate electrode The potential VG1 is equal to or lower than the gate threshold, and the potential VG2 of the gate electrode is equal to or higher than the gate threshold. Here, VG1 is set to the gate threshold value or more, and after the delay time τ1, VG2 is set to the gate threshold value or less to conduct the element. Next, VG2 is set to the gate threshold value or more, and after the delay time τ2, VG1 is set to the gate threshold value or less to put the element in the blocking state. In addition, when the potential of the main electrode corresponding to the low voltage side is higher than the potential of the main electrode corresponding to the high voltage side, the operation is performed in the same way by blocking the VG1 and VG2 of the gate electrode. The control which switches is performed.

Other than Patent Document 1, a general power conversion circuit (for example, an inverter device) in which a unidirectional switch and a diode are combined can be considered.
Japanese Patent No. 3183555

  In the gate driving method in such a conventional element configuration, when a forward / reverse voltage is applied to the main electrode when incorporated in a device, the logic needs to be reversed, and the power applied to the element configuration and the gate driving method is applied. The conversion circuit has a problem in that overcurrent and overvoltage occur in each part during the transition period.

  Further, when a load having an inductance component (for example, a motor) is connected to the output side of the power conversion circuit, it is difficult to form a closed loop for flowing a reflux current. That is, when the bidirectional switch is arranged on the upper and lower arms, it is necessary to provide a dead time for preventing a short circuit current due to an arm short circuit as a typical example of the unintended current loop described above. This is because there is a period in which are simultaneously turned off.

  Further, in general power conversion circuits (for example, inverter devices) other than Patent Document 1, since a unidirectional switch is combined, it can be realized by a simple gate driving method, while a motor or the like When a load having an inductance component is connected, since the return current flows through the diode and returns, there is a problem that the loss in the conversion circuit becomes large, so that a device such as a cooling fin or a cooling fan becomes large.

  The present invention solves such a conventional problem, and provides a gate drive method of a low-loss bidirectional switch while preventing unintentional overcurrent and overvoltage from occurring in control. It is aimed.

  In order to achieve the above object, the bidirectional switch gate driving method according to the present invention is formed with a semiconductor layer stack having a channel formed on a substrate and a gap between the semiconductor layer stack and the semiconductor layer stack. A first gate formed in order from the first ohmic electrode side between the first ohmic electrode and the second ohmic electrode, and between the first ohmic electrode and the second ohmic electrode An electrode, a second gate electrode, a first p-type semiconductor layer formed between the semiconductor layer stack and the first gate electrode, and between the semiconductor layer stack and the second gate electrode. A first gate terminal that inputs a gate drive signal between the first ohmic electrode and the first gate electrode, and the second ohmic electrode. And the second gate electrode A second gate terminal for inputting a gate driving signal, a drain terminal connected to the first ohmic electrode, and a source terminal connected to the second ohmic electrode, and only the first gate terminal When turning on only the second gate terminal, the first mode operates as a semiconductor in which a bidirectional device and a reverse diode are connected in series from the drain terminal toward the source terminal. A second mode in which a forward diode and an on-state bidirectional device operate as a semiconductor connected in series from the terminal to the source terminal, and when the first gate terminal and the second gate terminal are turned on, the drain terminal A first mode, wherein the first gate operates in a bidirectional manner without a diode between the source terminal and the source terminal. A gate driving method applied to a bidirectional switch having a fourth mode that cuts off current in forward and reverse directions when the child and the second gate terminal are turned off, wherein the control means is configured to control the third mode to the third mode. Alternatively, the gate drive method of the bidirectional switch is controlled so as not to directly shift from the third mode to at least one of the fourth modes.

  By this method, variation in on / off time between chips due to signal circuit or feedback capacitance to bidirectional switch with four operation modes and response of mutual gate drive circuit driving first gate terminal and second gate terminal Due to variations in characteristics, when the mode is shifted from the third mode to the fourth mode or from the fourth mode to the third mode, an unintended current flow mode (for example, either the second mode or the third mode) is passed. Thus, even if there is a delay in signal conveyance, control can be performed so as to pass through one of the intended other modes.

  Further, the control means passes through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction in the state transition from the fourth mode to the third mode. To control.

  With this method, the current between the drain terminal and the source terminal can be controlled to be in the intended flow direction when transitioning from the bi-directional off state to the bi-directional on state. Even when the is connected, power conversion can be performed with a simple circuit configuration without requiring a clamp circuit or the like.

  Further, the control means passes through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. To control.

  With this method, the current between the drain terminal and the source terminal can be controlled to be in the intended flow direction when transitioning from the bi-directional on state to the bi-directional off state. Even if is connected, power conversion can be performed with a simple circuit configuration without interrupting the current.

  Further, the control means passes through the first mode or the second mode in which a reverse diode is formed so as to cut off the intended conduction direction at the time of the state transition from the fourth mode to the third mode. The loss due to the forward current of the forward diode is reduced.

  With this method, when switching from a bi-directionally off state to a bi-directional on state, the entire circuit is low-loss without interposing a mode through which a diode that exists equivalently in the first or second mode flows. The power conversion can be performed with a smaller circuit configuration.

  Further, the control means passes through the first mode or the second mode in which the reverse diode is formed so as to be cut off with respect to the intended conduction direction in the state transition from the third mode to the fourth mode. The loss due to the forward current of the forward diode is reduced.

  With this method, when switching from bi-directional on to bi-directional off, the entire circuit is low-loss without intervening the mode of passing the diode that exists equivalently in the first or second mode. The power conversion can be performed with a smaller circuit configuration.

  Further, the drive signal for the first gate terminal and the drive signal for the second gate terminal are shared, and the first gate terminal and the second gate terminal are controlled to be turned on / off by a single gate drive signal via the control means.

  According to this method, it is not necessary to output two signals per one element as a gate driving signal from the microprocessor, which can be simplified and can be configured at a lower cost.

  Furthermore, a bridge circuit is configured using a bidirectional switch, and a reverse diode is formed so that the control means cuts off the intended conduction direction at the time of the state transition from the third mode to the fourth mode. By controlling to pass through the first mode or the second mode, the loss due to the forward current of the forward diode is reduced, and in the state transition from the fourth mode to the third mode, the intended conduction direction is reduced. On the other hand, the loss of the bidirectional switch is averaged by controlling to pass through the first mode or the second mode in which the forward diode is formed so as to be conducted.

  With this method, when bidirectional switches are connected in series or in parallel, the amount of heat generated is equalized, eliminating the need to select heat sinks based on bidirectional switches that generate a large amount of heat. A simple power conversion device can be configured.

  In addition, a bridge circuit is configured using a bidirectional switch, and a forward diode is formed so that the control means conducts in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. The first diode or the second mode is controlled, and a reverse diode is formed so as to cut off the intended conduction direction during the state transition from the fourth mode to the third mode. By controlling to pass through the one mode or the second mode, the loss due to the forward current of the forward diode is reduced, and the loss of the bidirectional switch is averaged.

  With this method, when bidirectional switches are connected in series or in parallel, the amount of heat generated is equalized, eliminating the need to select heat sinks based on bidirectional switches that generate a large amount of heat. A simple power conversion device can be configured.

  Further, the control means includes a delay generation means, and the first gate terminal and the second gate terminal are switched from OFF to ON or from ON to OFF at different timings.

  By this method, since the signal is switched with a delay time, the bidirectional switch can be prevented from directly shifting from the third mode to the fourth mode or from the fourth mode to the third mode with a simpler configuration.

  Further, the delay time of the delay generation means is at least 1 ns or more.

  With this method, there are four operation modes due to variations in on / off time between chips due to semiconductor input / output or feedback capacitance, and variations in responsiveness of the gate drive circuits for driving the first gate terminal and the second gate terminal. It is possible to prevent the operation mode transition of the bidirectional switch from passing through an unintended operation mode.

  Furthermore, the delay generation means generates a delay time using the response speed of the logic circuit.

  By this method, the generation of the delay time can be realized with a simple and inexpensive circuit.

  Moreover, the power converter device (for example, inverter device) which uses the gate drive method of a bidirectional switch is comprised.

  By this means, the bidirectional switch can be applied to the power conversion device with a simpler configuration, and a low-loss and inexpensive device can be configured.

  According to the present invention, a semiconductor layer stack having a channel formed on a substrate, and a first ohmic electrode and a second ohmic electrode formed on the semiconductor layer stack at a distance from each other; A first gate electrode and a second gate electrode formed in order from the first ohmic electrode side between the first ohmic electrode and the second ohmic electrode, and the semiconductor layer stack And a first p-type semiconductor layer formed between the semiconductor layer stack and the second gate electrode. , A first gate terminal for inputting a gate drive signal between the first ohmic electrode and the first gate electrode, and a gate drive signal between the second ohmic electrode and the second gate electrode. Input the second gate terminal and the front A drain terminal connected to the first ohmic electrode; and a source terminal connected to the second ohmic electrode; when only the first gate terminal is turned on, the drain terminal is turned on between the source terminals. The first mode in which the bidirectional device in the state and the reverse diode operate as a semiconductor connected in series, when only the second gate terminal is turned on, the forward diode and the on-state are turned from the drain terminal to the source terminal A second mode in which the bidirectional device operates as a semiconductor connected in series, and when the first gate terminal and the second gate terminal are turned on, the bidirectional connection is established between the drain terminal and the source terminal without a diode. The third mode that operates in the forward and reverse directions when the first gate terminal and the second gate terminal are turned off A gate driving method applied to a bidirectional switch having a fourth mode for cutting off a flow, wherein the control means directly changes from the fourth mode to at least one of the third mode and the third mode to the fourth mode. This is a gate drive method for a bidirectional switch that is controlled so as not to make a transition. The signal gate to the bidirectional switch having four operation modes or the variation in the on / off time between chips due to the feedback capacitance, and the first gate terminal When the transition from the third mode to the fourth mode or from the fourth mode to the third mode occurs due to variations in responsiveness of the gate drive circuits that drive the second gate terminal, an unintended current flow mode (for example, the first mode) Avoids passing through either the second mode or the third mode), and the other mode is intended even if there is a delay in signal transmission It is possible to provide a gate drive method for a bidirectional switch that can be controlled so as to pass through.

  Further, the control means passes through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction in the state transition from the fourth mode to the third mode. Can be controlled so that the current between the drain terminal and the source terminal is in the intended flow direction when transitioning from the bidirectional off state to the bidirectional on state. Even when an inductive load is connected, it is possible to provide a bidirectional switch gate driving method capable of performing power conversion with a simple circuit configuration without requiring a clamp circuit or the like.

  Further, the control means passes through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. Can be controlled so that the current between the drain terminal and the source terminal is in the intended flow direction when transitioning from the bi-directional on state to the bi-directional off state. Even when an inductive load is connected, it is possible to provide a bidirectional switch gate driving method capable of performing power conversion with a simple circuit configuration without interrupting the current.

  Further, the control means passes through the first mode or the second mode in which a reverse diode is formed so as to cut off the intended conduction direction at the time of the state transition from the fourth mode to the third mode. This is a diode that exists equivalently in the first or second mode when switching from the bi-directional off state to the bi-directional on state by reducing the loss due to the forward current of the forward diode. It is possible to provide a gate drive method for a bidirectional switch that can configure the entire circuit with low loss without involving a flow mode and can perform power conversion with a smaller circuit configuration.

  Further, the control means passes through the first mode or the second mode in which the reverse diode is formed so as to be cut off with respect to the intended conduction direction in the state transition from the third mode to the fourth mode. Therefore, when switching from the bi-directional on state to the bi-directional off state, the entire circuit can be controlled without intervening a mode through which an equivalent diode exists in the first or second mode. It is possible to provide a gate drive method for a bidirectional switch that can be configured with low loss and can perform power conversion with a smaller circuit configuration.

  In addition, the gate signal by sharing the drive signal of the first gate terminal and the drive signal of the second gate terminal, and controlling the first gate terminal and the second gate terminal with a single gate drive signal through the control means, the gate As a driving signal, it is not necessary to output two signals per one element from the microprocessor, and it is possible to provide a bidirectional switch gate driving method that can be simplified and can be configured at a lower cost.

  Furthermore, a bridge circuit is configured using a bidirectional switch, and a reverse diode is formed so that the control means cuts off the intended conduction direction at the time of the state transition from the third mode to the fourth mode. By controlling to pass through the first mode or the second mode, the loss due to the forward current of the forward diode is reduced, and in the state transition from the fourth mode to the third mode, the intended conduction direction is reduced. The bidirectional switch is connected in series or parallel by averaging the loss of the bidirectional switch by controlling to pass through the first mode or the second mode in which the forward diode is formed so as to be conductive. When connecting to a power converter, each heat generation amount is equalized, and there is no need to select a heat sink based on a bidirectional switch with a large heat generation amount. Possible to provide a gate driving method of the bidirectional switch that can be formed.

  In addition, a bridge circuit is configured using a bidirectional switch, and a forward diode is formed so that the control means conducts in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. The first diode or the second mode is controlled, and a reverse diode is formed so as to cut off the intended conduction direction during the state transition from the fourth mode to the third mode. By controlling to pass through one mode or the second mode, the loss due to the forward current of the forward diode is reduced, and by averaging the loss of the bidirectional switch, the bidirectional switch is connected in series or in parallel. In this case, each heat generation amount is equalized, and there is no need to select a heat sink based on a bidirectional switch that generates a large amount of heat generation. Possible to provide a gate driving method of the bidirectional switch that can.

  Further, the control means includes a delay generation means, and makes the signal have a delay time by setting the first gate terminal and the second gate terminal from off to on or from on to off at different timings. Therefore, it is possible to provide a gate drive method for a bidirectional switch that can prevent a direct switch from the third mode to the fourth mode or from the fourth mode to the third mode with a simpler configuration.

  Also, by setting the delay time of the delay generating means to at least 1 ns or more, variation in on / off time between chips due to semiconductor input / output or feedback capacitance, and mutual gates for driving the first gate terminal and the second gate terminal It is possible to provide a gate drive method for a bidirectional switch that can prevent the operation mode transition of the bidirectional switch having four operation modes from passing through an unintended operation mode due to variation in response of the drive circuit.

  Furthermore, the delay generation means generates a delay time using the response speed of the logic circuit, and can provide a gate drive method for a bidirectional switch that can be realized with a simple and inexpensive circuit. .

  In addition, by configuring a power conversion device (for example, an inverter device) using a bidirectional switch gate driving method, it is possible to provide a power conversion device with a simple configuration, low loss, and low cost.

  According to a first aspect of the present invention, there is provided a semiconductor layer stack having a channel formed on a substrate, a first ohmic electrode and a first ohmic electrode formed on the semiconductor layer stack at a distance from each other. A first gate electrode and a second gate electrode formed in order from the first ohmic electrode side between the two ohmic electrodes, the first ohmic electrode, and the second ohmic electrode; A first p-type semiconductor layer formed between the semiconductor layer stack and a first gate electrode; and a second p-type formed between the semiconductor layer stack and a second gate electrode. A first gate terminal that inputs a gate drive signal between the first ohmic electrode and the first gate electrode, and the second ohmic electrode and the second gate electrode. The second gate that inputs the gate drive signal between A drain terminal connected to the first ohmic electrode, and a source terminal connected to the second ohmic electrode, when only the first gate terminal is turned on, the drain terminal to the source terminal A first mode in which a bidirectional device that is in an on state and a reverse diode operate as a semiconductor connected in series, and when only the second gate terminal is turned on, forward direction from the drain terminal to the source terminal A second mode in which a diode and an on-state bidirectional device operate as a semiconductor connected in series, and when both the first gate terminal and the second gate terminal are turned on, no diode is interposed between the drain terminal and the source terminal The third mode operating to conduct in the direction, turning off the first gate terminal and the second gate terminal A gate driving method applied to a bidirectional switch having a fourth mode that cuts off current in both forward and reverse directions, wherein the control means is configured to switch from the fourth mode to the third mode or from the third mode to the fourth mode. It is a gate drive method of a bidirectional switch that is controlled so that it does not shift directly to at least one, variation of on / off time between chips due to a signal circuit or feedback capacitance to a bidirectional switch having four operation modes, Unintentional current flow when switching from the third mode to the fourth mode or from the fourth mode to the third mode due to variations in the response of the gate drive circuits that drive the first and second gate terminals. Avoid passing through a mode (for example, either the second mode or the third mode), and even if there is a delay in signal transport It has the effect that it can be controlled to go through the other mode.

  Further, the control means passes through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction in the state transition from the fourth mode to the third mode. It can be controlled so that the current between the drain terminal and the source terminal becomes the intended flow direction when transitioning from the bidirectional off state to the bidirectional on state. Even when an inductive load is connected to the power source, the power conversion can be performed with a simple circuit configuration without requiring a clamp circuit or the like.

  Further, the control means passes through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. When switching from the bi-directional on state to the bi-directional off state, it can be controlled so that the current between the drain terminal and the source terminal is in the intended flow direction. Even when an inductive load is connected, power conversion can be performed with a simple circuit configuration without interrupting the current.

  Further, the control means passes through the first mode or the second mode in which a reverse diode is formed so as to cut off the intended conduction direction at the time of the state transition from the fourth mode to the third mode. To reduce loss due to the forward current of the forward diode, and is equivalent to the first or second mode when switching from the bi-directional off state to the bi-directional on state. The entire circuit can be configured with low loss without interposing a mode through which a diode flows, and power conversion can be performed with a smaller circuit configuration.

  Further, the control means passes through the first mode or the second mode in which the reverse diode is formed so as to be cut off with respect to the intended conduction direction in the state transition from the third mode to the fourth mode. To reduce the loss due to the forward current of the forward diode, and is equivalent to the first or second mode when switching from the bi-directional on state to the bi-directional off state. The entire circuit can be configured with low loss without interposing a mode through which a diode flows, and power conversion can be performed with a smaller circuit configuration.

  Further, the drive signal for the first gate terminal and the drive signal for the second gate terminal are shared, and the first gate terminal and the second gate terminal are controlled to be turned on and off with a single gate drive signal through the control means, It is not necessary to output two signals per one element from the microprocessor as gate driving signals, so that the operation can be simplified and the structure can be reduced.

  Furthermore, a bridge circuit is configured using a bidirectional switch, and a reverse diode is formed so that the control means cuts off the intended conduction direction at the time of the state transition from the third mode to the fourth mode. By controlling to pass through the first mode or the second mode, the loss due to the forward current of the forward diode is reduced, and in the state transition from the fourth mode to the third mode, the intended conduction direction is reduced. The loss of the bidirectional switch is averaged by controlling to pass through the first mode or the second mode in which the forward diode is formed so as to be conductive with the bidirectional switch. When connected in parallel, the amount of heat generated is equalized, eliminating the need to select a heat sink based on a bidirectional switch that generates a large amount of heat. An effect that can be configured.

  In addition, a bridge circuit is configured using a bidirectional switch, and a forward diode is formed so that the control means conducts in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. The first diode or the second mode is controlled, and a reverse diode is formed so as to cut off the intended conduction direction during the state transition from the fourth mode to the third mode. By controlling to pass through one mode or the second mode, the loss due to the forward current of the forward diode is reduced, and the loss of the bidirectional switch is averaged. The bidirectional switch is connected in series or in parallel. When connected, the amount of heat generated is equalized, and there is no need to select a heat sink based on a bidirectional switch that generates a large amount of heat. It has the effect that it is possible.

  Further, the control means includes a delay generation means, and the timing of switching the first gate terminal and the second gate terminal from off to on, or from on to off is different, so that the signal has a delay time. Therefore, the bidirectional switch can be prevented from directly shifting from the third mode to the fourth mode or from the fourth mode to the third mode with a simpler configuration.

  Further, the delay time of the delay generating means is at least 1 ns or more, the variation in the on / off time between the chips due to the input / output of the semiconductor or the feedback capacitance, and the mutual driving of the first gate terminal and the second gate terminal. Due to the responsiveness variation of the gate drive circuit, the operation of the bidirectional switch having the four operation modes can be prevented from passing through an unintended operation mode.

  Furthermore, the delay generation means generates a delay time using the response speed of the logic circuit, and has an effect that the generation of the delay time can be realized with a simple and inexpensive circuit.

  Further, the power conversion device (for example, an inverter device) using the bidirectional switch gate drive method is configured, and has an effect that a simple configuration, a low loss, and an inexpensive power conversion device can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The configuration of the bidirectional switch 1 will be described with reference to FIG. As shown in FIG. 1, the bidirectional switch 1 includes a first gate terminal 2, a second gate terminal 3, a drain terminal 4, and a source terminal 5. The bidirectional switch 1 has a thickness of 1 μm formed by alternately laminating 10 nm thick aluminum nitride (AlN) and 10 nm thick gallium nitride (GaN) on a substrate 6 made of silicon (Si). A buffer layer 7 is formed, and a semiconductor layer stack 8 is formed thereon. In the semiconductor layer stacked body 8, a first semiconductor layer and a second semiconductor layer having a band gap larger than that of the first semiconductor layer are sequentially stacked from the substrate side. The first semiconductor layer is a GaN (undoped gallium nitride) layer 9 having a thickness of 2 μm, and the second semiconductor layer is an n-type AlGaN (aluminum gallium nitride) layer 10 having a thickness of 20 nm. In the vicinity of the hetero interface between the GaN layer 9 and the AlGaN layer 10, charges are generated due to spontaneous polarization and piezoelectric polarization. Accordingly, and mobility 1 × 1013cm- ² or sheet carrier concentration channel region is generated a 1000 cm ² V / sec or more two-dimensional electron gas (2DEG) layer. On the semiconductor layer stacked body 8, a first ohmic electrode 11A and a second ohmic electrode 11B are formed at a distance from each other. The first ohmic electrode 11A and the second ohmic electrode 11B are formed by stacking titanium (Ti) and aluminum (Al), and form an ohmic junction with the channel region. Further, in order to reduce the contact resistance, a part of the AlGaN layer 10 is removed and the GaN layer 9 is dug down by about 40 nm, so that the first ohmic electrode 11A and the second ohmic electrode 11B become the AlGaN layer 10 and the GaN layer 9. The example formed so that it may contact | connect an interface with is shown. Note that the first ohmic electrode 11 </ b> A and the second ohmic electrode 11 </ b> B may be formed on the AlGaN layer 10. In the region between the first ohmic electrode 11A and the second ohmic electrode 11B on the n-type AlGaN layer 10, the first p-type semiconductor layer 12A and the second p-type semiconductor layer 12B are spaced from each other. And selectively formed. A first gate electrode 13A is formed on the first p-type semiconductor layer 12A, and a second gate electrode 13B is formed on the second p-type semiconductor layer 12B. The first gate electrode 13A and the second gate electrode 13B are each formed by stacking palladium (Pd) and gold (Au), and the first p-type semiconductor layer 12A and the second p-type semiconductor layer 12B. Ohmic contact. A protective film 14 made of silicon nitride (SiN) is formed so as to cover the AlGaN layer 10, the first p-type semiconductor layer 12A, and the second p-type semiconductor layer 12B. By forming the protective film 14, it is possible to ensure a defect that causes so-called current collapse and to improve current collapse. The first p-type semiconductor layer 12A and the second p-type semiconductor layer 12B each have a thickness of 300 nm and are made of p-type GaN doped with magnesium (Mg). The first p-type semiconductor layer 12A, the second p-type semiconductor layer 12B, and the AlGaN layer 10 form PN junctions. As a result, when the voltage between the first ohmic electrode 11A and the first gate electrode 13A is 0 V, for example, the depletion layer spreads from the first p-type GaN layer into the channel region, so that the current flowing through the channel is cut off. Similarly, when the voltage between the second ohmic electrode 11B and the second gate electrode 13B is, for example, 0 V or less, a depletion layer spreads from the second p-type GaN layer into the channel region. Thus, a semiconductor element capable of interrupting a current flowing through the channel and performing a so-called normally-off operation is realized. The potential of the first ohmic electrode 11A is V1, the potential of the first gate electrode 13A is V2, the potential of the second gate electrode 13B is V3, and the potential of the second ohmic electrode 11B is V4. In this case, if V2 is higher than V1 by 1.5V or more, the depletion layer extending from the first p-type semiconductor layer 12A into the channel region is reduced, so that a current can flow in the channel region. Similarly, if V3 is higher than V4 by 1.5V or more, the depletion layer extending from the second p-type semiconductor layer 12B into the channel region is reduced, and current can flow through the channel region. That is, the so-called threshold voltage of the first gate electrode 13A and the so-called threshold voltage of the second gate electrode 13B are both 1.5V. In the following, the threshold voltage of the first gate electrode 13A at which the depletion layer extending in the channel region below the first gate electrode 13A is reduced and current can flow through the channel region is set to the first threshold voltage. The threshold voltage is set to the second gate electrode 13B so that the depletion layer extending in the channel region on the lower side of the second gate electrode 13B is reduced and current can flow in the channel region. The threshold voltage is used. The distance between the first p-type semiconductor layer 12A and the second p-type semiconductor layer 12B can withstand the maximum voltage applied to the first ohmic electrode 11A and the second ohmic electrode 11B. Constitute. A gate drive signal (that is, a control signal to the first gate terminal 2) is input between the first ohmic electrode 11A and the first gate electrode 13A. Similarly, a gate drive signal (that is, a control signal to the second gate terminal 3) is input between the second ohmic electrode 11B and the second gate electrode 13B. The source terminal 5 is connected to the first ohmic electrode 11A, the drain terminal 4 is connected to the second ohmic electrode 11B, the first gate terminal 2 is connected to the first gate electrode 13A, and the second gate terminal. 3 is connected to the second gate electrode 13B.

  Next, the operation of the bidirectional switch 1 will be described. For explanation, the potential of the first ohmic electrode 11A is set to 0V, the voltage applied to the first gate terminal 2 is Vg1, the voltage applied to the second gate terminal 3 is Vg2, and the second ohmic electrode 11B and the first The voltage between the ohmic electrode 11A is Vs2s1, and the current flowing between the second ohmic electrode 11B and the first ohmic electrode 11A is Is2s1.

  When V4 is higher than V1, for example, when V4 is + 100V and V1 is 0V, the input voltages Vg1 and Vg2 of the first gate terminal 2 and the second gate terminal 3 are set to the first threshold voltage and the first threshold voltage, respectively. A voltage equal to or lower than a threshold voltage of 2, for example, 0V. As a result, the depletion layer extending from the first p-type semiconductor layer 12A extends in the channel region toward the second p-type GaN layer, so that the current flowing through the channel can be blocked. Therefore, even when V4 is a positive high voltage, it is possible to realize a cut-off state in which a current flowing from the second ohmic electrode 11B to the first ohmic electrode 11A is cut off. On the other hand, when V4 is lower than V1, for example, even when V4 is −100 V and V1 is 0 V, the depletion layer extending from the second p-type semiconductor layer 12B is in the channel region in the first p-type semiconductor layer. The current spreads in the direction of 12A and can flow through the channel. For this reason, even when a negative high voltage is applied to the second ohmic electrode 11B, the current flowing from the first ohmic electrode 11A to the second ohmic electrode 11B can be blocked. That is, the bidirectional current of the bidirectional switch 1 can be cut off.

  In the structure and operation as described above, the first gate electrode 13A and the second gate electrode 13B share a channel region for ensuring a withstand voltage. In this device, the bidirectional switch 1 can be realized with the area of the channel region for one device. Considering the entire bidirectional switch 1, two diodes and two normally-off type AlGaN / GaN-HFETs are provided. The chip area can be reduced as compared with the case where it is used, and the bidirectional switch 1 can be reduced in cost and size.

  Next, when the input voltages Vg1 and Vg2 of the first gate terminal 2 and the second gate terminal 3 are higher than the first threshold voltage and the second threshold voltage, respectively, for example, 5V, the first voltage Both of the voltages applied to the gate electrode 13A and the second gate electrode 13B are higher than the threshold voltage. Accordingly, since the depletion layer does not extend from the first p-type semiconductor layer 12A and the second p-type semiconductor layer 12B to the channel region, the channel region is also formed below the first gate electrode 13A. It is not pinched off on the lower side of 13B. As a result, it is possible to realize a conductive state in which a current flows bidirectionally between the first ohmic electrode 11A and the second ohmic electrode 11B.

  Next, the operation when Vg1 is higher than the first threshold voltage and Vg2 is equal to or lower than the second threshold voltage will be described. When the bidirectional switch 1 having the first gate terminal 2 and the second gate terminal 3 is represented by an equivalent circuit, a first transistor 15 and a second transistor 16 are connected in series as shown in FIG. It can be regarded as a circuit. In this case, the source (S) of the first transistor 15 corresponds to the first ohmic electrode 11A, the gate (G) of the first transistor 15 corresponds to the first gate electrode 13A, and the source ( S) corresponds to the second ohmic electrode 11B, and the gate (G) of the second transistor 16 corresponds to the second gate electrode 13B. In such a circuit, for example, when Vg1 is 5V and Vg2 is 0V, the fact that Vg2 is 0V is equivalent to the state where the gate and the source of the second transistor 16 are short-circuited. Can be regarded as a circuit as shown in FIG.

  Further, description will be made assuming that the source (S) of the second transistor 16 shown in FIG. 2B is the A terminal, the drain (D) is the B terminal, and the gate (G) is the C terminal. When the potential of the B terminal shown in the figure is higher than the potential of the A terminal, it can be regarded as a transistor in which the A terminal is a source and the B terminal is a drain. In such a case, the C terminal (gate) and the A terminal Since the voltage between the source and the source is 0 V and is equal to or lower than the threshold voltage, no current flows from the B terminal (drain) to the A terminal (source). On the other hand, when the potential of the A terminal is higher than the potential of the B terminal, the transistor can be regarded as a transistor in which the B terminal is a source and the A terminal is a drain. In such a case, since the potentials of the C terminal (gate) and the A terminal (drain) are the same, when the potential of the A terminal is equal to or lower than the threshold voltage with respect to the B terminal, the A terminal (drain) to the B terminal Do not supply current to the (source). When the potential of the A terminal becomes equal to or higher than the threshold voltage with reference to the B terminal, a voltage higher than the threshold voltage is applied to the gate with reference to the B terminal (source), and current flows from the A terminal (drain) to the B terminal (source). be able to. That is, when the gate and the source of the transistor are short-circuited, the transistor functions as a diode having a drain as a cathode and a source as an anode, and the forward rising voltage becomes the threshold voltage of the transistor. Therefore, the portion of the second transistor 16 shown in FIG. 2A can be regarded as a diode, and an equivalent circuit as shown in FIG. In the equivalent circuit shown in FIG. 2C, when the potential of the drain terminal 4 of the bidirectional switch 1 is higher than the potential of the source terminal 5, 5 V is applied to the first gate terminal 2 of the first transistor 15. In this case, the first transistor 15 is in an on state, and a current can flow from S2 to S1. However, an on-voltage is generated due to the forward rising voltage of the diode. Further, when the potential of S1 of the bidirectional switch 1 is higher than the potential of S2, the voltage is carried by the diode composed of the second transistor 16, and the current flowing from S1 to S2 of the bidirectional switch 1 is blocked. That is, by applying a voltage equal to or higher than the threshold voltage to the first gate terminal 2 and applying a voltage equal to or lower than the threshold voltage to the second gate terminal 3, a so-called bidirectional device is turned on and the cathode side of the diode is connected in series to the drain side. A switch capable of connected operation can be realized.

  FIG. 3 shows the relationship between Vs2s1 and Is2s1 of the bidirectional switch 1. FIG. 3A shows a case where Vg1 and Vg2 are changed simultaneously, and FIG. 3B shows a case where Vg2 is 0 V that is equal to or lower than the second threshold voltage. (C) shows a case where Vg2 is changed with Vg1 being 0 V which is equal to or lower than the first threshold voltage. In FIG. 3, the voltage between S2 and S1 (Vs2s1), which is the horizontal axis in FIG. 3, is a voltage based on the first ohmic electrode 11A, and the current between S2 and S1 (Is2s1), which is the vertical axis, is the second ohmic. The current flowing from the electrode 11B to the first ohmic electrode 11A is positive. As shown in FIG. 3A, when Vg1 and Vg2 are 0 V and 1 V, Is2s1 does not flow regardless of whether Vs2s1 is positive or negative, and the bidirectional switch 1 is cut off. . Further, when both Vg1 and Vg2 become higher than the threshold voltage, a conductive state in which Is2s1 flows bidirectionally according to Vs2s1 is established. On the other hand, as shown in FIG. 3B, when Vg2 is set to 0 V that is equal to or lower than the second threshold voltage and Vg1 is set to 0 V that is equal to or lower than the first threshold voltage, Is2s1 is blocked in both directions. However, when Vg1 is 2V to 5V that is equal to or higher than the first threshold voltage, Is2s1 does not flow when Vs2s1 is less than 1.5V, but Is2s1 flows when Vs2s1 becomes 1.5V or higher. That is, a reverse blocking state is reached in which current flows only from the second ohmic electrode 11B to the first ohmic electrode 11A, and no current flows from the first ohmic electrode 11A to the second ohmic electrode 11B. Further, when Vg1 is set to 0V and Vg2 is changed, as shown in FIG. 3C, a current flows only from the first ohmic electrode 11A to the second ohmic electrode 11B, and the second ohmic electrode A reverse blocking state in which no current flows from 11B to the first ohmic electrode 11A is obtained.

  As described above, the bidirectional switch 1 has a function of interrupting and energizing the bidirectional current according to the gate bias condition, and can also operate as a diode, and the direction in which the current of the diode is energized can be switched. As described above, the operation can be performed in the four operation modes shown in FIG. 4 according to the ON or OFF condition of the first gate terminal 2 and the second gate terminal 3 of the bidirectional switch 1. That is, when only the first gate terminal 2 is turned on, the first mode operates as a semiconductor in which a bidirectional device and a reverse diode are connected in series from the drain terminal 4 to the source terminal 5; When only the second gate terminal 3 is turned on, the first gate operates as a semiconductor in which a forward diode and an on-state bidirectional device operate in series from the drain terminal 4 to the source terminal 5. When the terminal 2 and the second gate terminal 3 are turned on, the third mode operates so as to conduct in a bidirectional manner without a diode between the drain terminal 4 and the source terminal 5, the first gate terminal 2 and the first gate terminal 3. When the two-gate terminal 3 is turned off, it has a fourth mode in which current is cut off in both forward and reverse directions. This structure is similar to a JFET, but operates on a completely different operating principle from a JFET that performs carrier modulation in a channel region by a gate electric field in that carrier injection is intentionally performed. Specifically, it operates as a JFET up to a gate voltage of 3V. However, when a gate voltage of 3V or more exceeding the built-in potential of the pn junction is applied, holes are injected into the gate, and the current flows through the mechanism described above. Increases, and a large current and low on-resistance operation becomes possible.

  In the bidirectional switch 1, the first gate electrode 13A is formed on the first p-type semiconductor layer 12A having p-type conductivity, and the second gate electrode 13B has p-type conductivity. It is formed on the second p-type semiconductor layer 12B. For this reason, a forward bias is applied from the first gate electrode 13A and the second gate electrode 13B to the channel region generated in the interface region between the first semiconductor layer and the second semiconductor layer. Thus, holes can be injected into the channel region. In a nitride semiconductor, the mobility of holes is much lower than the mobility of electrons, so that holes injected into the channel region hardly contribute as carriers for passing current. For this reason, holes injected from the first gate electrode 13A and the second gate electrode 13B generate the same amount of electrons in the channel region, so that the effect of generating electrons in the channel region is increased, and the donor is increased. It functions like an ion. That is, since the carrier concentration can be modulated in the channel region, it is possible to realize a normally-off type nitride semiconductor layer bidirectional switch having a large operating current.

  Next, the control means 17 for driving the gate of the bidirectional switch 1 will be described with reference to FIG.

  As shown in the figure, the control means 17 is disposed on the first gate terminal 2 and the second gate terminal 3 via a gate drive circuit. The internal structure of the control means 17 was created in correspondence with the four operation modes shown in FIG. 4 so as not to directly shift between the fourth mode that is bidirectionally off and the third mode that is bidirectionally on. It is configured to output with reference to the on / off table shown in FIG. Hereinafter, an inverter device 18 as a power conversion device when output with reference to this on / off table will be described with reference to FIG. In FIG. 7, the main circuit is composed of the bidirectional switches 1a to 1f. The bidirectional switches 1a to 1f output four drive modes referring to the on / off table to the first gate terminals 2a to 2f and the second gate terminals 3a to 3f, respectively, by controlling the four modes. Transition. That is, when shifting from the fourth mode to the third mode, until the transition from the bidirectionally shut-off state of the fourth mode of the table to the energized state of the third mode bidirectionally or when performing the reverse operation For example, if the intended current flow direction is from the drain terminal 4 to the source terminal 5, the second mode is interposed. In the second mode, a diode is formed in the forward direction with respect to the intended conduction direction, and the bidirectional switch 1 forms a conduction path having a diode that is turned on only in the forward direction. . When the lower arm of each of the bidirectional switches 1a to 1f is turned off, the current can be supplied in the intended direction until the moment when both the first gate terminal 2 and the second gate terminal 3 are turned off. To do. Next, when the control unit 17 shifts from the fourth mode in which current is cut off in both directions to the third mode in which current is supplied in both directions, the control unit 17 changes from the state in which the table is cut off in both directions in the fourth mode. Mode in which a reverse diode is formed with respect to the intended conduction direction (for example, if the intended current flow direction is the direction from the drain terminal 4 to the source terminal 5). Control to shift to the third mode with the first mode) interposed. Conversely, when shifting from the third mode in which current is passed in both directions to the fourth mode in which current is cut off in both directions, the mode is similarly shifted from the third mode to the fourth mode via the first mode. To control. However, in this control, for example, when an inductive load is connected to the load side of the inverter device 18 as shown in FIG. 7, the mode of the bidirectional switch 1 a of the first arm 18 a is changed. Refer to the second mode so that the bidirectional switch 1b can make a mode transition so that a return current can flow from the negative side of the DC section and the bidirectional switch 1a and the bidirectional switch 1b do not cause a short circuit between the upper and lower arms. Control to change mode. In this case, the bidirectional switch 1b operates with a diode interposed therebetween, and the bidirectional switch 1a does not generate an energizing operation with a diode interposed.

  As described above, the first gate terminal 2, the second gate terminal 3, the drain terminal 4, and the source terminal 5 are provided, and when only the first gate terminal 2 is turned on, the drain terminal 4 and the source terminal 5 are bidirectionally connected. When the device ON state and the cathode side of the reverse diode operate as a semiconductor connected in series and only the second gate terminal 3 is turned ON, the forward diode and the cathode of the forward diode are connected between the drain terminal 4 and the source terminal 5. When the first gate terminal 2 and the second gate terminal 3 are turned on, they operate so as to conduct in a bidirectional manner without a diode between the drain terminal 4 and the source terminal 5, When the first gate terminal 2 and the second gate terminal 3 are turned off, the gate drive of the bidirectional switch 1 having the characteristic of interrupting the current in both forward and reverse directions By turning on only one direction, either forward or reverse, that allows current to flow in the intended direction, so that the transition from the bi-directional off state to the bi-directional on state or the reverse transition does not directly shift. Due to variations in on / off time between chips due to a signal circuit or feedback capacitance to a bidirectional switch having two operation modes, and variations in responsiveness of mutual gate drive circuits for driving the first gate terminal 2 and the second gate terminal 3 , Avoiding going through an unintended current flow mode (for example, either the second mode or the third mode) during the transition from the third mode to the fourth mode or from the fourth mode to the third mode. Even if there is a delay in signal conveyance, the gate of the bidirectional switch 1 can be controlled so that it can be controlled to pass through one of the other modes. To become. In the example of the inverter device 18, when the bidirectional switch 1 b makes a state transition from the fourth mode to the third mode, it passes through the first mode in which a forward diode is formed with respect to the intended conduction direction. In the transition from the bidirectional off state to the bidirectional on state, the current between the drain terminal 4 and the source terminal 5 can be controlled to be in the intended flow direction. Even when an inductive load such as a motor is connected to the output side as in this embodiment, the power conversion can be performed with a simple circuit configuration without requiring a clamp circuit or the like.

  Note that the number and arrangement of the bidirectional switches 1 may be changed according to the modulation method of the inverter device 18.

  In addition, the on / off table has a logic circuit or the like as shown in FIG. 8 for any one of the output terminals of the control means 17 (for example, a signal propagation time of 10 ns for realizing a signal propagation time of 1 ns or more). The logic IC) may be added, and the circuit may be driven by a signal delayed by the delay time of the logic circuit without shifting directly.

  In addition, the drive signal for the first gate terminal 2 and the drive signal for the second gate terminal 3 are shared, and the first gate terminal 2 and the second gate terminal 3 are controlled to be turned on and off with a single gate drive signal via the control means 17. It is good also as a structure like FIG.

(Embodiment 2)
Hereinafter, the gate driving method of the bidirectional switch 1 will be described in the second embodiment with reference to FIG.

  In addition, what has the same function as Embodiment 1 attaches | subjects the same code | symbol, and abbreviate | omits detailed description.

  As shown in FIG. 9A, when the control unit 17 shifts the bidirectional switch 1a from the fourth mode in which current is cut off in both directions to the third mode in which current is supplied in both directions, the intended conduction direction. On the other hand, a mode in which a reverse diode is formed is interposed to control to shift to the third mode. The on / off table at this time corresponds by controlling to move from the table (1) to the table (4) via the table (3). On the contrary, when shifting from the third mode in which current is supplied in both directions to the fourth mode in which current is cut off in both directions, as shown in FIG. 9B, the table (4) to the table (3) Control is performed so as to shift to the table (1) via. However, in this control, when an inductive load is connected to the load side of the inverter device 18, for example, when the mode of the bidirectional switch 1a of the first arm 18a is changed, the mode of the bidirectional switch 1b of the first arm 18a is changed. In order to allow a reflux current to flow from the N side of the DC section and to prevent the bidirectional switch 1a and the bidirectional switch 1b from causing an upper and lower arm short circuit, the table (3) is also provided to the bidirectional switch 1b. Control to perform mode transition with reference. In this case, the bidirectional switch 1b operates with a diode, and the bidirectional switch 1a does not generate an energizing operation with a diode.

  As described above, the control means 17 shifts from the fourth mode in which current is cut off in both directions to the third mode in which current is supplied in both directions. Or, when shifting from the third mode in which current is passed in both directions to the fourth mode in which current is cut off in both directions, a mode in which a reverse diode is formed with respect to the intended conduction direction is interposed, and the third mode Even when the bidirectional switch 1b passes through the first or second mode, no current is generated at that time, and loss due to the forward voltage of the diode is prevented. can do.

(Embodiment 3)
Hereinafter, the gate driving method of the bidirectional switch 1 will be described in the third embodiment with reference to FIG.

  In addition, what has the same function as Embodiment 1 or 2 attaches | subjects the same code | symbol, and abbreviate | omits detailed description.

  As shown in FIG. 10, the control means 17 forms a reverse diode with respect to the intended conduction direction when the bidirectional switch 1a in the inverter device 18 undergoes a state transition from the third mode to the fourth mode. By controlling to pass through the first mode, the loss due to the forward current of the forward diode is reduced, and the intended conduction direction (direction of the return current) during the state transition from the fourth mode to the third mode In contrast, the first gate terminal 2a and the second gate terminal 3a are controlled so as to pass through a second mode in which a forward diode is formed. On the other hand, the bidirectional switch 1b of the first arm 18a performs control so as to secure a current route at the timing when the bidirectional switch 1a enters the current cutoff state with respect to the intended current direction. For example, in the case of the combination (2), the second gate terminal 3b is turned on. Conversely, control is also performed for the state transition of the bidirectional switch 1b so as to ensure a current route in the bidirectional switch 1a. The bidirectional switch 1a and the bidirectional switch 1b go through the mode in which current flows through the diode once by combination (2) and (4). Since the bidirectional switch 1a and the bidirectional switch 1b go through the timing of passing the diode once as shown by the arrows in the figure, the losses are averaged with each other.

  As described above, the time ratio for forming the current route between the bidirectional switches 1a and 1b through the diodes can be made equal, and the loss of the mutual bidirectional switches 1a and 1b when the bridge circuit is formed can be reduced. There is no need to design heat dissipation according to the bidirectional switch 1a or 1b which can be averaged and has a large loss, and a small and light power converter can be configured.

(Embodiment 4)
Hereinafter, the gate driving method of the bidirectional switch 1 will be described in the fourth embodiment with reference to FIG.

  In addition, what has the same function as Embodiments 1-3 attaches | subjects the same code | symbol, and abbreviate | omits detailed description.

  As shown in FIG. 11, the control means 17 forms a forward diode with respect to the intended conduction direction when the bidirectional switch 1a in the inverter device 18 undergoes a state transition from the third mode to the fourth mode. Control is performed via the first mode or the second mode, and a reverse diode is formed with respect to the intended conduction direction at the time of the state transition from the fourth mode to the third mode. By controlling so as to pass through the mode, the loss due to the forward current of the forward diode is reduced, and the loss of the bidirectional switches 1a and 1b when the bridge circuit is formed is averaged. Specifically, the first gate terminals 2a and 2b and the second gate terminals 3a and 3b are sequentially turned on and off as in combination (5) to combination (8). In the bidirectional switch 1a of the combination (6), the current direction indicated by the broken line does not flow, but the bidirectional switch 1b does not flow through the bidirectional switch 1a in the transition period at the moment when the combination shifts. However, the direction in which a cross mark is given to the broken line means that the path of the other bidirectional switch 1a or bidirectional switch 1b is given priority. Therefore, the bidirectional switch 1a and the bidirectional switch 1b generate a path that passes through the forward diode with respect to each other mainly once. In addition, control is performed so that the number of times is the same for the bidirectional on state and the bidirectional off state.

  As described above, the time ratio for forming the current route between the bidirectional switches 1a and 1b through the diodes can be made equal, and the loss of the mutual bidirectional switches 1a and 1b when the bridge circuit is formed can be reduced. It is possible to average, and it is not necessary to perform a heat radiation design in accordance with the lossy bidirectional switch 1a or 1b, and a small and lightweight power conversion device can be configured.

  The present invention can be applied to a gate driving method when a bidirectional switch having four states is used in a DC-DC converter device, an AC-DC converter device, an inverter device, or the like.

Configuration diagram of bidirectional switch according to Embodiment 1 of the present invention Equivalent circuit diagram of the bidirectional switch ((a) Equivalent circuit diagram composed of first and second transistors, (b) Equivalent circuit diagram of the second transistor, (c) The second transistor is regarded as a diode. Equivalent circuit diagram) Correlation diagram of voltage and current of the bidirectional switch Diagram showing the operation mode of the bidirectional switch Explanatory drawing of the control means that performs the gate drive The same on / off table Configuration diagram of the inverter device The figure which shows the generation circuit of the same signal delay Mode transition diagram of bidirectional switch in embodiment 2 of the present invention ((a) transition diagram from fourth mode to third mode, (b) transition diagram from third mode to fourth mode) Mode transition diagram of bidirectional switch in embodiment 3 of the present invention Mode transition diagram of bidirectional switch in embodiment 4 of the present invention Explanatory drawing of the drive method of the bidirectional switch in the conventional patent document 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bidirectional switch 1a-1f Bidirectional switch 2 1st gate terminal 2a-2f 1st gate terminal 3 2nd gate terminal 3a-3f 2nd gate terminal 4 Drain terminal 5 Source terminal 6 Substrate 7 Buffer layer 8 Semiconductor layer laminated body 9 GaN layer 10 AlGaN layer 11A 1st ohmic electrode 11B 2nd ohmic electrode 12A 1st p-type semiconductor layer 12B 2nd p-type semiconductor layer 13A 1st gate electrode 13B 2nd gate electrode 14 Protective film 15 First transistor 16 Second transistor 17 Control means 18 Inverter device 18a First arm

Claims (12)

A semiconductor layer stack having a channel formed on a substrate; a first ohmic electrode and a second ohmic electrode formed on the semiconductor layer stack spaced apart from each other; and the first ohmic electrode. A first gate electrode, a second gate electrode, and the semiconductor layer stack and the first gate electrode, which are sequentially formed from the first ohmic electrode side between the electrode and the second ohmic electrode; A first p-type semiconductor layer formed between the semiconductor layer stack and a second gate electrode, and the first ohmic contact. A first gate terminal for inputting a gate drive signal between an electrode and the first gate electrode; and a second gate for inputting a gate drive signal between the second ohmic electrode and the second gate electrode A terminal and the first ohmic A drain terminal connected to the electrode and a source terminal connected to the second ohmic electrode, and when only the first gate terminal is turned on, the bidirectional state is turned on between the drain terminal and the source terminal A first mode in which a device and a reverse diode operate as a semiconductor connected in series, when only the second gate terminal is turned on, a forward diode and an on-state bidirectional device from the drain terminal to the source terminal A second mode that operates as a semiconductor connected in series, and when the first gate terminal and the second gate terminal are turned on, the second mode operates to conduct in both directions without a diode between the drain terminal and the source terminal. When the three-mode, the first gate terminal and the second gate terminal are turned off, the current is cut off in both forward and reverse directions. A gate driving method applied to a bidirectional switch having a mode, wherein the control means controls so as not to directly shift from the fourth mode to at least one of the third mode and the third mode to the fourth mode. Bidirectional switch gate drive method. The control means controls to pass through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction at the time of the state transition from the fourth mode to the third mode. The gate drive method of the bidirectional switch according to claim 1. The control means is controlled to pass through the first mode or the second mode in which the forward diode is formed so as to conduct in the intended conduction direction at the time of the state transition from the third mode to the fourth mode. The gate drive method of the bidirectional switch according to claim 1. The control means controls to pass through the first mode or the second mode in which a reverse diode is formed so as to cut off the intended conduction direction at the time of the state transition from the fourth mode to the third mode. 2. The gate drive method for a bidirectional switch according to claim 1, wherein a loss due to a current flowing through the forward diode is reduced. The control means controls to pass through the first mode or the second mode in which a reverse diode is formed so as to cut off the intended conduction direction at the time of the state transition from the third mode to the fourth mode. 2. The gate drive method for a bidirectional switch according to claim 1, wherein a loss due to a current flowing through the forward diode is reduced. 8. The driving signal for the first gate terminal and the driving signal for the second gate terminal are shared, and the first gate terminal and the second gate terminal are controlled to be turned on and off only by the control means. The gate drive method of the bidirectional switch as described in 2. A bridge circuit is configured using a bidirectional switch, and the control means includes a reverse diode formed so as to cut off the intended conduction direction at the time of the state transition from the third mode to the fourth mode. By controlling to go through one mode or the second mode, the loss due to the forward current of the forward diode is reduced, and in the state transition from the fourth mode to the third mode, the intended conduction direction is reduced. 2. The bidirectional switch gate drive method according to claim 1, wherein the loss of the bidirectional switch is averaged by controlling to pass through a first mode or a second mode in which a forward diode is formed to be conductive. . A bridge circuit is configured using a bidirectional switch, and the control means includes a forward diode formed so as to conduct in the intended conduction direction during the state transition from the third mode to the fourth mode. A first mode in which a reverse diode is formed so as to be cut off with respect to the intended conduction direction during the state transition from the fourth mode to the third mode, controlled to pass through one mode or the second mode. 2. The bidirectional switch gate drive method according to claim 1, wherein the loss caused by the forward current of the forward diode is reduced by controlling to pass through the second mode, and the loss of the bidirectional switch is averaged. 2. The bidirectional switch gate drive method according to claim 1, wherein the control means includes delay generation means, and the first gate terminal and the second gate terminal are switched from OFF to ON or from ON to OFF at different timings. 10. The bidirectional switch gate drive method according to claim 9, wherein the delay time of the delay generation means is at least 1 ns. 10. The bidirectional switch gate driving method according to claim 9, wherein the delay generation means generates a delay time by using a response speed of the logic circuit. The power converter device using the gate drive method of the bidirectional | two-way switch in any one of Claim 1 to 11.

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