JP2010068606A - Single phase-three phase matrix converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems of a matrix converter which employs a bi-directional switch and converts single phase directly into three phase that a clamp circuit, and the like, are required for conducting the circulation current from an inductive load, that the apparatus is enlarged, the control is complicated and the cost is increased because a high performance microprocessor is required for gate drive. <P>SOLUTION: A single phase-three phase matrix converter is constituted by applying a bi-directional switch 1 including a first gate terminal 2, a second gate terminal 3, a drain terminal 4 and a source terminal 5 and having four operation modes by turning the first gate terminal 2 and second gate terminal 3 on/off, respectively, wherein the first gate terminal 2 and second gate terminal 3 are driven optimally so that the number of gate signals is decreased by performing gate drive partially while ensuring a route for feeding a circulation current to the bi-directional switch 1 thus attaining simple circuitry at a low cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a single-phase to three-phase matrix converter that employs 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, a matrix converter has been proposed as a power conversion method for reducing power consumption of this type.

  Hereinafter, the matrix converter will be described using Patent Document 1 as an example.

  FIG. 12 shows a three-phase to three-phase matrix converter 102 that converts the three-phase AC power source 101 into three-phase power having different frequencies or voltage amplitudes. In the three-phase to three-phase matrix converter 102, since the input potential of each phase is different, a gate drive pulse that generates a commutation pattern is generated according to the magnitude relationship of each phase voltage, the load side is not opened, Even when an inductive load is connected, an event of applying an excessive surge voltage to the switch does not occur.

  Patent Document 2 will be described as an example of a three-phase to three-phase matrix converter that employs a snubber circuit that can also be applied to secure a path for flowing a return current of a single-phase to three-phase matrix converter.

FIG. 13 shows a three-phase to three-phase matrix converter 103, to which a snubber capacitor 104, a discharge means 105, and a full-wave rectifier circuit 106 are added. When an inductive load is connected to the load side of the three-phase to three-phase matrix converter 103, the snubber capacitor 104 is charged via the full-wave rectifier circuit 105. In this configuration, during the dead time period provided for the bidirectional switches 107 to 115 of the three-phase to three-phase matrix converter 103 to prevent a power supply short circuit, the return current is passed through the full-wave rectifier circuit 106 and the snubber capacitor 104. Is charged. Further, the electric charge charged in the snubber capacitor is discharged by the discharging means 105.
JP 2004-312912 A JP 2004-274906 A

  In such a conventional matrix converter return current processing method, when a single-phase power supply is used as an input, each phase of the output has only one phase input, so a commutation pattern is generated by comparing the magnitude relationship. Since the gate drive pulse to be generated cannot be generated, the method as in Patent Document 1 cannot be applied to a single-phase to three-phase matrix converter, and avoids a power supply short-circuit due to simultaneous turning-on of switches of the half-bridge circuit Therefore, during the dead time period, each phase on the load side is in an open state, and there is a problem that a path for flowing a reflux current cannot be secured.

  Further, in the method as in Patent Document 2 using a snubber circuit for generating a path for flowing a reflux current, it is necessary to provide a circuit for consuming by connecting a diode to each phase and connecting to a capacitor or a discharging means. There is a problem that the number of components increases and the cost increases.

  Furthermore, in a single-phase to three-phase matrix converter using a bidirectional switch in which unidirectional switches are connected in series, the forward current when supplying to the load side passes through a diode paired with the IGBT or MOSFET. There is a problem that the loss increases and the apparatus becomes large.

  In addition, in the driving of each bidirectional switch of the single-phase to three-phase matrix converter, six bidirectional switches are required for the three-phase load. It is necessary to output signals, and because the processing inside the microcomputer is large, complex, and high speed, it is necessary to select a high-performance microprocessor or to provide an external IC for driving the gate. There was a problem of high costs.

  The present invention solves such a conventional problem, secures a path for the return current to flow while avoiding a power supply short circuit, and reduces the forward current when supplying to the load side with a low loss. It is also an object of the present invention to provide a single-phase to three-phase matrix converter that can reduce the number of gate signals for driving and does not require selection of a high-performance microcomputer.

  The single-phase to three-phase matrix converter of the present invention includes a semiconductor layer stack having a channel formed on a substrate, a first ohmic electrode formed on the semiconductor layer stack and spaced from each other, and A first ohmic electrode, and a first gate electrode and a second gate electrode, which are sequentially formed from the first ohmic electrode side between the first ohmic electrode and the second ohmic electrode; A first p-type semiconductor layer formed between the semiconductor layer stack and the first gate electrode, and a second p formed 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, the second ohmic electrode, and the second gate electrode. Gate drive signal during A drain terminal connected to the first ohmic electrode, a source terminal connected to the second ohmic electrode, and when only the first gate terminal is turned on, the drain terminal A first mode in which a bidirectional device and a reverse diode that are in an ON state are connected in series from the source terminal to the source terminal and operate as a semiconductor connected in series, and when only the second gate terminal is turned ON, between the drain terminal and the source terminal A forward mode diode and an on-state bidirectional device operate as a semiconductor connected in series. When the first gate terminal and the second gate terminal are turned on, a diode is connected between the drain terminal and the source terminal. A third mode which operates to conduct in both directions without passing through the first gate terminal and the second gate A half-bridge circuit is formed by connecting a bidirectional switch having a fourth mode that cuts off current in both forward and reverse directions when the child is turned off to form a half-bridge circuit, and this half-bridge circuit is arranged in parallel. The matrix converter is configured to control the return current from the load connected to the output to flow through the bidirectional switch.

  By this means, it is possible to secure a path for flowing a return current from a load connected to the output, and to connect a diode to each phase, and to provide a capacitor or a circuit that consumes the diode, thereby reducing components. Thus, the cost can be reduced and the size can be reduced.

  In addition, when two bidirectional switches are connected in series and a half bridge circuit is connected, the gate terminals are arranged from the positive pole side when the voltage phase of the single-phase AC power supply has a positive polarity. The first gate terminal and the second gate terminal are arranged in this order.

  By this means, it is possible to secure a path for flowing a return current from a load connected to the output, and to connect a diode to each phase, and to provide a capacitor or a circuit that consumes the diode, thereby reducing components. Thus, the cost can be reduced and the size can be reduced.

  In addition, when the voltage phase of the single-phase AC power supply has a positive polarity, the first gate terminal of each bidirectional switch is always turned on.

  By this means, it is possible to avoid a power supply short circuit while ensuring a path for flowing a return current from a load connected to the output.

  Furthermore, when the voltage phase of the single-phase AC power supply has a negative polarity, the second gate terminal of each bidirectional switch is always turned on.

  By this means, it is possible to avoid a power supply short circuit while ensuring a path for flowing a return current from a load connected to the output.

  Also, PWM control of each bidirectional switch is such that it outputs only to either the first gate terminal or the second gate terminal of each bidirectional switch according to the positive / negative polarity of the voltage phase of the single-phase AC power supply. It is a configuration.

  By this means, it is not necessary to generate 12 gate signals, the processing amount inside the microprocessor can be reduced, and a large-capacity, complicated and high-speed processing is eliminated, so that an inexpensive microprocessor can be obtained. Can be driven, and cost reduction can be achieved.

  Furthermore, when the single-phase AC power supply has a positive polarity voltage phase, the first gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and the off-state The configuration is as follows.

  By this means, even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, the first gate terminal is always turned on intentionally according to the polarity. A power supply short circuit can be avoided.

  In addition, when the single-phase AC power supply has a negative polarity voltage phase, the second gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and the off-state The configuration is as follows.

  By this means, even if an error occurs in voltage detection of the single-phase AC power supply or a minute vibration occurs in the zero cross, the second gate terminal is always turned on intentionally according to the polarity. A power supply short circuit can be avoided.

  Further, when the voltage of the single-phase AC power supply has a positive polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is not more than a predetermined value, the first gate terminal of each bidirectional switch is always on. The configuration is such that the state is canceled and turned off.

  By this means, even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, the first gate terminal is always turned on intentionally according to the polarity. A power supply short circuit can be avoided.

  In addition, when the voltage of the single-phase AC power supply has a negative polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is not more than a predetermined value, the second gate terminal of each bidirectional switch is always on. The configuration is such that the state is canceled and turned off.

  By this means, even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, the first gate terminal is always turned on intentionally according to the polarity. A power supply short circuit can be avoided.

  Furthermore, the bidirectional switch for canceling the normally-on state of the first gate terminal is configured to be either one of the bidirectional switches connected in series in each half bridge circuit.

  By this means, even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, the first gate terminal is always turned on intentionally according to the polarity. Loss can be reduced while avoiding a power supply short circuit.

  Further, the bidirectional switch for canceling the always-on state of the second gate terminal is configured to be either one of the bidirectional switches connected in series in each half bridge circuit.

  By this means, even if an error occurs in voltage detection of the single-phase AC power supply or a minute vibration occurs in the zero cross, the second gate terminal is always turned on intentionally according to the polarity. Loss can be reduced while avoiding a power supply short circuit.

  Furthermore, the bidirectional switch for canceling the normally-on state of the first gate terminal is configured such that bidirectional switches connected in series are alternately performed.

  By this means, even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, the first gate terminal is always turned on intentionally according to the polarity. While avoiding a power supply short circuit, the loss can be reduced, and the loss can be distributed without concentrating on a specific bidirectional switch, and the radiator can be further downsized.

  In addition, the bidirectional switch for canceling the always-on state of the second gate terminal is configured such that bidirectional switches connected in series are alternately performed.

  By this means, even if an error occurs in voltage detection of the single-phase AC power supply or a minute vibration occurs in the zero cross, the second gate terminal is always turned on intentionally according to the polarity. While avoiding a power supply short circuit, the loss can be reduced, and the loss can be distributed without concentrating on a specific bidirectional switch, and the radiator can be further downsized.

  Furthermore, one of the two-way switches connected in series in each half-bridge circuit corresponding to the path of the return current from the load side is always kept on, and the other always-on state is released. It is what.

  By this means, it is possible to avoid a power supply short circuit on the bidirectional switch side not corresponding to the path while reducing the loss of the part corresponding to the return current path.

  Further, the PWM signal is generated by an individual signal from the microprocessor.

  By this means, the circuit components necessary for generating the PWM signal can be reduced, which can be realized at low cost.

  Further, the PWM signal is generated by comparing the modulation rate output from the microprocessor with the carrier signal output from the external circuit.

  By this means, control other than the control of each bidirectional switch can be realized by one microprocessor in parallel, reducing the processing load on the microprocessor and at the same time ensuring simultaneity in each processing. Therefore, it is not necessary to input the signals of the respective detectors to a plurality of microprocessors, and the cost can be reduced.

  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 single-phase to three-phase matrix converter in which a half-bridge circuit is configured by connecting two-way switches having a fourth mode for interrupting a flow in series, and the half-bridge circuits are arranged in parallel, By adopting a configuration that controls the return current from the connected load to flow through the bidirectional switch, a path for the return current from the load connected to the output is secured, and a diode is connected to each phase. Thus, it is not necessary to provide a circuit that is consumed by a capacitor or a diode, the number of components can be reduced, and a single-phase to three-phase matrix converter that can be reduced in cost and size can be provided.

  In addition, when two bidirectional switches are connected in series and a half bridge circuit is connected, the gate terminals are arranged from the positive pole side when the voltage phase of the single-phase AC power supply has a positive polarity. A single-phase to three-phase matrix converter arranged in the order of one gate terminal and second gate terminal, and configured to control the return current from the load connected to the output to flow through the bidirectional switch As a result, it is not necessary to secure a path for the return current from the load connected to the output to flow, connect the diode to each phase, and use a capacitor or diode to reduce the number of components. Thus, it is possible to provide a single-phase to three-phase matrix converter that can be reduced in cost and size.

  In addition, when the voltage phase of the single-phase AC power supply is positive, the first gate terminal of each bidirectional switch is always turned on so that the return current from the load connected to the output flows. A single-phase to three-phase matrix converter that can avoid a power supply short circuit while securing a route can be provided.

  In addition, when the voltage phase of the single-phase AC power supply is negative, the second gate terminal of each bidirectional switch is always turned on, so that a path for flowing the return current from the load connected to the output is provided. It is possible to provide a single-phase to three-phase matrix converter capable of avoiding a power supply short circuit while ensuring.

  Also, PWM control of each bidirectional switch is such that it outputs only to either the first gate terminal or the second gate terminal of each bidirectional switch according to the positive / negative polarity of the voltage phase of the single-phase AC power supply. With this configuration, it is not necessary to generate 12 gate signals, the amount of processing inside the microprocessor can be reduced, and it is inexpensive because it does not require large capacity, complexity, and high-speed processing. A single-phase to three-phase matrix converter that can be driven by a microprocessor and can be reduced in cost can be provided.

  Furthermore, when the single-phase AC power supply has a positive polarity voltage phase, the first gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and the off-state Even if an error occurs in the voltage detection of a single-phase AC power supply or a minute vibration at the zero cross occurs, the first gate terminal is always intentionally set according to the polarity. It is possible to provide a single-phase to three-phase matrix converter that can avoid a power supply short-circuit due to turning on.

  In addition, when the single-phase AC power supply has a negative polarity voltage phase, the second gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and the off-state Even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, the second gate terminal is always intentionally set according to the polarity. It is possible to provide a single-phase to three-phase matrix converter that can avoid a power supply short-circuit due to turning on.

  Further, when the voltage of the single-phase AC power supply has a positive polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is not more than a predetermined value, the first gate terminal of each bidirectional switch is always on. Even if an error occurs in the voltage detection of a single-phase AC power supply or a minute vibration occurs in the zero crossing, it is intentional depending on the polarity. In addition, it is possible to provide a single-phase to three-phase matrix converter capable of avoiding a power supply short circuit caused by always turning on the first gate terminal.

  In addition, when the voltage of the single-phase AC power supply has a negative polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is not more than a predetermined value, the second gate terminal of each bidirectional switch is always on. Even if an error occurs in the voltage detection of a single-phase AC power supply or a minute vibration occurs in the zero crossing, it is intentional depending on the polarity. In addition, it is possible to provide a single-phase to three-phase matrix converter capable of avoiding a power supply short circuit caused by always turning on the first gate terminal.

  Furthermore, the bidirectional switch for releasing the normally-on state of the first gate terminal is configured to be one of the bidirectional switches connected in series in each half-bridge circuit, thereby detecting the voltage of the single-phase AC power supply. Even if there is an error in the case or when a minute vibration occurs at the zero crossing, the loss is reduced while avoiding a power short-circuit caused by always turning on the first gate terminal intentionally according to the polarity. A single-phase to three-phase matrix converter can be provided.

  In addition, the bidirectional switch for canceling the normally-on state of the second gate terminal is configured to be one of the bidirectional switches connected in series in each half-bridge circuit, thereby detecting the voltage of the single-phase AC power supply. Even if there is an error in the case or when a minute vibration occurs at the zero crossing, the loss is reduced while avoiding a power supply short-circuit by always turning on the second gate terminal intentionally according to the polarity. A single-phase to three-phase matrix converter can be provided.

  Furthermore, the bidirectional switch for canceling the normally-on state of the first gate terminal is configured such that the bidirectional switches connected in series are alternately arranged, so that an error occurs in voltage detection of the single-phase AC power supply or Even if a minute vibration occurs at the zero cross, both the loss is reduced while avoiding a power short by intentionally turning on the first gate terminal according to the polarity. It is possible to provide a single-phase to three-phase matrix converter that can be distributed without concentrating on the direction switch and that can further reduce the size of the radiator.

  In addition, the bidirectional switch that releases the always-on state of the second gate terminal is configured such that bidirectional switches that are connected in series are alternately performed, so that an error occurs in voltage detection of the single-phase AC power supply or Even if a minute vibration occurs at the zero cross, both the loss is reduced and the loss is specified while avoiding a power short circuit by always turning on the second gate terminal intentionally according to the polarity. It is possible to provide a single-phase to three-phase matrix converter that can be distributed without concentrating on the direction switch and that can further reduce the size of the radiator.

  Furthermore, one of the two-way switches connected in series in each half-bridge circuit corresponding to the path of the return current from the load side is always kept on, and the other always-on state is released. By doing so, it is possible to provide a single-phase to three-phase matrix converter capable of avoiding a power supply short circuit on the bidirectional switch side not corresponding to the path while reducing the loss of the part corresponding to the path of the return current.

  In addition, by adopting a configuration in which the PWM signal is generated by an individual signal from the microprocessor, the circuit components necessary for generating the PWM signal can be reduced, and the single phase can be realized at low cost. A three-phase matrix converter can be provided.

  Further, the PWM signal is generated by comparing the modulation rate output from the microprocessor and the carrier signal output from the external circuit, so that other control than the control of each bidirectional switch is performed in parallel. Since it can be realized with one microprocessor, the processing burden on the microprocessor can be reduced, and at the same time, the simultaneity in each process can be secured, so there is no need to input the signal of each detector to multiple microprocessors, A single-phase to three-phase matrix converter capable of reducing the cost can be provided.

  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 This is a single-phase to three-phase matrix converter in which a half-bridge circuit is configured by connecting a bidirectional switch having a fourth mode that cuts off current in both forward and reverse directions in series to form a half-bridge circuit. And configured to control the flow of the return current from the load connected to the output to the bidirectional switch, ensuring a path for flowing the return current from the load connected to the output, and a diode. It is not necessary to provide a circuit that is consumed by a capacitor or a diode by connecting to each phase, so that the number of components can be reduced, and the cost and size can be reduced.

  In addition, when two bidirectional switches are connected in series and a half bridge circuit is connected, the gate terminals are arranged from the positive pole side when the voltage phase of the single-phase AC power supply has a positive polarity. 2. The single-phase to three-phase matrix converter according to claim 1, wherein a one-gate terminal and a second-gate terminal are arranged in this order so that a return current from a load connected to an output is passed through the bidirectional switch. It is necessary to provide a circuit that consumes the capacitor and the diode by connecting the diode to each phase by securing the path for the return current from the load connected to the output. Therefore, it is possible to reduce the number of components and to reduce the cost and size.

  In addition, when the voltage phase of the single-phase AC power supply is positive polarity, the first gate terminal of each bidirectional switch is always on, and the return current from the load connected to the output is It has the effect that a power supply short circuit can be avoided while securing a flow path.

  Furthermore, when the voltage phase of the single-phase AC power supply has a negative polarity, the second gate terminal of each bidirectional switch is always turned on, and the flow path for the return current from the load connected to the output It is possible to avoid a power supply short circuit while ensuring the above.

  Also, PWM control of each bidirectional switch is such that it outputs only to either the first gate terminal or the second gate terminal of each bidirectional switch according to the positive / negative polarity of the voltage phase of the single-phase AC power supply. It is configured, and it is not necessary to generate 12 gate signals, the amount of processing inside the microprocessor can be reduced, and it is inexpensive because it does not require large capacity, complexity, and high-speed processing. It can be driven by a simple microprocessor and has the effect of reducing the cost.

  Furthermore, when the single-phase AC power supply has a positive polarity voltage phase, the first gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and the off-state Even if an error occurs in the voltage detection of a single-phase AC power supply or a minute vibration occurs at the zero cross, the first gate terminal is intentionally set according to the polarity. It has the effect that it is possible to avoid a power supply short-circuit caused by always turning on.

  In addition, when the single-phase AC power supply has a negative polarity voltage phase, the second gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and the off-state Even if there is an error in the voltage detection of a single-phase AC power supply or a minute vibration at the zero cross occurs, the second gate terminal is intentionally set according to the polarity. It has the effect that it is possible to avoid a power supply short-circuit caused by always turning on.

  Further, when the voltage of the single-phase AC power supply has a positive polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is not more than a predetermined value, the first gate terminal of each bidirectional switch is always on. It is configured to release the state and turn off, and even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, it is intended according to the polarity. Therefore, it is possible to avoid a power supply short circuit caused by always turning on the first gate terminal.

  In addition, when the voltage of the single-phase AC power supply has a negative polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is not more than a predetermined value, the second gate terminal of each bidirectional switch is always on. It is configured to release the state and turn off, and even if an error occurs in the voltage detection of the single-phase AC power supply or a minute vibration at the zero cross occurs, it is intended according to the polarity. Therefore, it is possible to avoid a power supply short circuit caused by always turning on the first gate terminal.

  Further, the bidirectional switch for releasing the normally-on state of the first gate terminal is configured to be one of the bidirectional switches connected in series in each half bridge circuit, and the voltage of the single-phase AC power supply. Loss is reduced while avoiding power supply short-circuits by always turning on the first gate terminal intentionally according to the polarity, even when errors occur in detection or when minute vibrations occur at the zero cross. It has the effect of being able to.

  In addition, the bidirectional switch for releasing the normally-on state of the second gate terminal is configured as one of the serially connected bidirectional switches of each half-bridge circuit, and the voltage of the single-phase AC power supply Loss is reduced while avoiding a power short-circuit by always turning on the second gate terminal intentionally according to the polarity, even if an error occurs in detection or a minute vibration occurs at the zero cross. It has the effect of being able to.

  In addition, the bidirectional switch that releases the always-on state of the first gate terminal is configured to alternately perform bidirectional switches connected in series, and when an error occurs in voltage detection of a single-phase AC power supply. Even if a minute vibration occurs at the zero crossing, the loss is reduced while avoiding a power short by intentionally always turning on the first gate terminal according to the polarity. Dispersion can be achieved without concentrating on the bidirectional switch, and the radiator can be further downsized.

  In addition, the bidirectional switch that releases the always-on state of the second gate terminal is configured to alternately perform bidirectional switches connected in series, and when an error occurs in the voltage detection of the single-phase AC power supply. Even when a minute vibration occurs at the zero cross, the loss is reduced while the power supply short circuit caused by always turning on the second gate terminal intentionally according to the polarity is avoided, and the loss is specified. Dispersion can be achieved without concentrating on the bidirectional switch, and the radiator can be further downsized.

  Furthermore, one of the two-way switches connected in series in each half-bridge circuit corresponding to the path of the return current from the load side is always kept on, and the other always-on state is released. Thus, it is possible to avoid a power supply short circuit on the bidirectional switch side not corresponding to the path while reducing the loss of the part corresponding to the path of the return current.

  In addition, the PWM signal is generated by an individual signal from the microprocessor, and circuit components necessary for generating the PWM signal can be reduced, which can be realized at low cost. Have

  Further, the PWM signal is generated by comparing the modulation factor output from the microprocessor and the carrier signal output from the external circuit, and in parallel with other controls other than the control of each bidirectional switch. Since it can be realized by one microprocessor, the processing burden on the microprocessor can be reduced, and at the same time, the simultaneity in each processing can be secured, so there is no need to input the signals of each detector to a plurality of microprocessors. , It has the effect of reducing the cost.

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

(Embodiment 1)
First, 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. The voltage is equal to or lower than the 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 horizontal axis S2-S1 voltage (Vs2s1) is a voltage based on the first ohmic electrode 11A, and the vertical axis S2-S1 current (Is2s1) is the second ohmic voltage. 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. When Vg1 is set to 0 V 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 can also switch the direction in which the current of the diode is energized. 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 with a large operating current.

  Next, a single-phase to three-phase matrix converter 17 using the bidirectional switch 1 will be described with reference to FIG. As shown in the figure, the single-phase to three-phase matrix converter 17 connects the bidirectional switch 1 shown in FIGS. 1 and 2 in series as bidirectional switches 1a, 1b, 1c, 1d, 1e, and 1f. The gate terminals are arranged in the order of the first bridge terminal and the second gate terminal from one side of the single-phase AC power source, and the half-bridge circuits 18a, 18b, and 18c, and the bidirectional switches 1a to 1f. A drive control unit 19 that performs on / off control of each of the first gate terminals 2a to 2f and each of the second gate terminals 3a to 3f, and a microprocessor 20 that outputs only six systems of PWM signals to the drive control unit 19 are provided. Further, the microprocessor 20 outputs a polarity flag of the AC power supply voltage for selecting whether the PWM signal is output to the first gate terminals 2a to 2f or the second gate terminals 3a to 3f.

  Next, the drive control unit 19 that performs on / off control of the first gate terminals 2a to 2f and the second gate terminals 3a to 3f of the bidirectional switches 1a to 1f will be described with reference to FIG. As shown in the figure, the instantaneous target voltages of the U-phase, V-phase, and W-phase on the output side are Vu *, Vv *, and Vw *, and the input voltage of the single-phase AC power supply is Vac. The carrier signal is carry and the dead time setting is tdead. The control of the bidirectional switches 1a to 1f is different only in the instantaneous target voltage of each phase, and since the logic circuit is the same, only one phase is described in detail, and detailed description of the other phases is omitted. First, the single-phase to three-phase matrix converter 17 using the bidirectional switches 1a to 1f has a positive polarity on one side of the single-phase AC power supply according to the polarity of the input voltage of the single-phase AC power supply. The first gate terminals 2a to 2f are always turned on, and the second gate terminals 3a to 3f are PWM-controlled. If the polarity is negative, the second gate terminals 3a to 3f are always turned on, and the first gate terminals 2a to 2f are PWM-controlled. The output from the drive control unit 19 is supplied to the first gate terminals 2a to 2f and the second gate terminals 3a to 3f via the amplifier circuit. This operation will be described in order from the left input side in FIG. 6. In order to calculate the modulation factor for the U-phase instantaneous target voltage Vu *, the instantaneous voltage value Vac of the single-phase AC power supply is input. Considering as an instantaneous DC power supply, Vu * is divided by the absolute value ABS of the instantaneous voltage value of the single-phase AC power supply (ABS shown in FIG. 6 is an absolute value calculation logic). The further divided value is input to the limiter and limited by the upper and lower limit values. Here, since there is a moment when the absolute value of the instantaneous voltage value of the single-phase AC power supply becomes zero, the ABS is configured to add a minute voltage. The calculated modulation rate is compared with the carrier signal carry, and then the ON signal when the second gate terminal 3a has a positive polarity is limited only when the voltage Vac of the single-phase AC power supply has a positive polarity. Generate. Since the ON signal when the second gate terminal 3a has a positive polarity cannot be turned ON simultaneously with the ON signal when the second gate terminal 3b has a positive polarity, the time from the turn-off of the second gate terminal 3b to the dead time tdead It passes through the AND circuit 20a so as to turn on after a lapse. Further, the OR circuit 20b adds in the subsequent stage so that the negative polarity voltage is always turned on. Further, the second gate terminal 3b paired with the second gate terminal 3a in a half-bridge circuit has a dead time tdead when the second gate terminal 3a is turned on and when the second gate terminal 3a is turned off as an off time, Set other times as on-time.

  As described above, the PWM control of the bidirectional switches 1a to 1f is performed only on one of the first gate terminals 2a to 2f or the second gate terminals 3a to 3f according to the positive / negative polarity of the voltage phase of the single-phase AC power supply. When the PWM control is not performed, the output is always on.

  Next, with respect to an example of the operation by the drive signal supplied to the first gate terminals 2a to 2f and the second gate terminals 3a to 3f, the case where the input voltage of the single-phase AC power supply has a positive polarity will be described with reference to FIG. . As shown in the figure, when the input voltage of the single-phase AC power supply is positive, the bidirectional switches 1a to 1f are always on, so that the bidirectional switches 1a to 1f are Either state (1) or state (3) shown in FIG. In the state (1), the forward current can be cut off and the reverse current can be made to flow. In the state (3), since the current can be made to flow in both the forward and reverse directions, the bidirectional switch 1a is turned on ( At the time of transition to 3), the phase voltage of the U phase becomes substantially equal to the input voltage of the single-phase AC power supply.

  When the second gate terminal 3a of the bidirectional switch 1a is turned off while the current is flowing to the motor as shown in FIG. 7, the state transitions from the state (3) to the state (1), and the forward current is cut off. However, since the bidirectional switch 1b is in the state (1) at that time, the path of the return current circulates from the bidirectional switch 1b to the bidirectional switch 1d via the motor as a load. Is formed. Then, after the first gate terminal 2a of the bidirectional switch 1a is turned off, the bidirectional switch 1b is changed from the state (1) to the state (3), so that the forward voltage of the diode is maintained while maintaining the path of the return current. Therefore, the loss of the bidirectional switch 1b is reduced. Further, for example, by setting the other bidirectional switch 1d through which the reflux current flows at that time to the state (3), a path through the bidirectional switches 1a to 1f is formed as a path of the reflux current. In the figure, an equivalent circuit when the second gate terminals 3a, 3d, and 3f are turned on is shown. When the polarity of the input voltage of the single-phase AC power supply is inverted, that is, when the input voltage of the single-phase AC power supply is negative, the bidirectional switches 1a to 1f are always on for the second gate terminals 3a to 3b. Each of the bidirectional switches 1a to 1f is in a state (1) or a state (3) shown in FIG. As described above, the bidirectional switches 1a, 1c, and 1e and the bidirectional switches 1b, 1d, and 1f are similarly controlled by performing the reverse control with respect to the control of the first gate terminals 2a to 2f and the second gate terminals 3a to 3b. Can be controlled.

  As described above, in the single-phase to three-phase matrix converter 17 employing the bidirectional switches 1a to 1f, a path for flowing the return current from the load connected to the output is secured, a diode is connected to each phase, and the capacitor In addition, it is not necessary to provide a circuit that is consumed by a diode or a diode, the number of components can be reduced, and a power supply short circuit can be avoided. Further, it is not necessary to generate 12 gate signals, the amount of processing inside the microprocessor can be reduced, and the necessity for processing with a large capacity, complexity, and high speed can be eliminated. Furthermore, since the PWM signal is generated by an individual signal from the microprocessor, the circuit components necessary for generating the PWM signal can be reduced, and can be realized at low cost.

(Embodiment 2)
Hereinafter, the drive control unit 19 according to the second embodiment will be described 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.

  In FIG. 8, when the single-phase AC power supply has a positive polarity voltage phase, not all the first gate terminals 2 a to 2 f during a predetermined time (for example, 200 μs) immediately before the phase when the voltage becomes zero, When only the first gate terminals 2a, 2c, and 2e are always released from the on state and turned off, and the single-phase AC power supply has a negative polarity voltage phase, a predetermined time immediately before the phase when the voltage becomes zero (for example, 200 μs) ), Only the second gate terminals 3b, 3d, and 3f are always released from the on state and turned off, not all the second gate terminals 3a to 3f.

  Specifically, a zero-cross synchronization signal is input from the PLL circuit 20d to the off-timing generator 20c, and the off-timing generator 20c determines a predetermined time (for example, 200 μs) based on the cycle of the single-phase AC power supply from the counter value between zero crosses. ) Is subtracted from the counter value. Then, the off-timing generator 20c decrements from the subtracted counter value at each zero cross timing, and when the counter value becomes zero, if the detected value of the single-phase AC power supply voltage is positive, the off-timing generator 20c is controlled to be always on. The first gate terminals 2a, 2c, and 2e that have been released are always turned off (that is, the logic output is shifted from 1 to 0), and the detected value of the single-phase AC power supply voltage is negative, The always-on state of the controlled second gate terminals 3b, 3d, and 3f is released.

  As described above, the first gate terminal 2 is always turned on intentionally according to the polarity even when an error occurs in the voltage detection of the single-phase AC power supply or when a minute vibration at the zero cross occurs. The power supply short circuit can be avoided, and only one of the first gate terminals 2a, 2c, 2e or the second gate terminals 3b, 3d, 3f is always released from the on state, thereby reducing loss. Can be planned.

  Although the predetermined time is 200 μs, there is no difference in operational effects even if the time is changed according to the power supply environment of the single-phase AC power supply or the voltage detection accuracy on the device side.

(Embodiment 3)
Hereinafter, the drive control unit 19 according to Embodiment 3 will be described 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.

  In FIG. 9, when the single-phase AC power supply has a positive polarity voltage phase, the off-timing generator 20e determines that the first gate terminal 2a, when the absolute value of the voltage is a predetermined value (eg, 3V) or less. 2c, 2e, when the always-on state is canceled and the single-phase AC power supply is in the negative polarity voltage phase, the absolute value is greater than or equal to a predetermined value (for example, -3V), the second gate The terminals 3b, 3d, and 3f are released from the always-on state and turned off. Further, the bidirectional switches 1a, 1c, 1e or the bidirectional switches 1b, 1d, 1f that have been released from the always-on state last time are stored, and the next-time always-on states of the first gate terminal 2 and the second gate terminal 3 are released. The bidirectional switch 1 is configured to release the first gate terminal 2 and the second gate terminal 3 of the bidirectional switch 1 that do not match the previous switch.

  As described above, the second gate terminal should always be turned on intentionally according to the polarity even when there is an error in the voltage detection of the single-phase AC power supply or when there is a minute vibration at the zero cross. In addition, it is possible to avoid a power supply short circuit due to the above, and it is possible to reduce the loss because only one of the first gate terminals 2a, 2c, 2e or the second gate terminals 3b, 3d, 3f is always released. be able to.

(Embodiment 4)
Hereinafter, an example of gate drive control of the single-phase to three-phase matrix converter 17 in the fourth embodiment will be described 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.

  In FIG. 10, the second gate terminal 3d of the bidirectional switch 1d is always kept on after the serially connected bidirectional switch 1a of the half bridge circuit 18a corresponding to the path of the return current from the load side is turned off.

  As described above, one of the bidirectional switches 1a to 1f corresponding to the path of the return current from the load side can be kept in the always-on state, and the other always-on state can be released. The power supply short circuit can be avoided on the bidirectional switch side not corresponding to the path while reducing the loss of the part corresponding to the path.

(Embodiment 5)
Hereinafter, the drive control unit 19 according to the fifth embodiment will be described with reference to FIG.

  In addition, what has the same function as Embodiments 1-4 attaches | subjects the same code | symbol, and abbreviate | omits detailed description.

  In the drive control unit 19 shown in FIG. 11, the microprocessor 20 calculates and outputs a modulation factor, generates a carrier signal carry in an external circuit, compares it with the carrier signal carry in an external circuit, and a single-phase AC power source in a logic circuit Only when the voltage Vac is a positive polarity voltage, an ON signal is generated when the second gate terminal 3a has a positive polarity. Since the ON signal when the second gate terminal 3a has a positive polarity cannot be turned ON simultaneously with the ON signal when the second gate terminal 3b has a positive polarity, the time from the turn-off of the second gate terminal 3b to the dead time tdead After the elapse of time, an AND circuit 20a is passed through an external circuit so as to turn on. In addition, an addition is performed in the OR circuit 20b of the external circuit in the subsequent stage so that the negative polarity voltage is always turned on. Further, the second gate terminal 3b paired with the second gate terminal 3a in a half-bridge circuit has a dead time tdead when the second gate terminal 3a is turned on and when the second gate terminal 3a is turned off as an off time, Set other times as on-time.

  As described above, the control other than the gate drive control of the bidirectional switches 1a to 1f can be realized by one microprocessor 20 in parallel, and the processing load on the microprocessor 20 can be reduced. It is possible to ensure simultaneity in each process.

  The present invention provides an AC-AC direct conversion circuit mainly composed of a high-efficiency and low-cost motor inverter as a single-phase to three-phase matrix converter circuit using a bidirectional switch having four states by controlling a gate signal. Applicable.

Configuration diagram of bidirectional switch according to Embodiment 1 of the present invention Equivalent circuit diagram of the bidirectional switch Correlation diagram of voltage and current of the bidirectional switch Diagram showing the operation mode of the bidirectional switch Configuration diagram of the single-phase to three-phase matrix converter 17 Explanatory drawing of the drive control unit 19 The figure which shows the operation example of the same drive signal Explanatory drawing of the drive control part 19 in Embodiment 2 of this invention. Explanatory drawing of the drive control part 19 in Embodiment 3 of this invention. Operational explanatory diagram of the single-phase to three-phase matrix converter in Embodiment 4 of the present invention Explanatory drawing of the drive control part 19 in Embodiment 5 of this invention Configuration diagram of matrix converter in conventional Patent Document 1 Configuration diagram of matrix converter in conventional Patent Document 2

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 Single-phase to three-phase matrix converter 18a to 18c Half bridge circuit 19 Drive controller 20 Microprocessor

Claims (16)

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; And a first p-type semiconductor layer formed between the semiconductor layer stack and the 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. This is a single-phase to three-phase matrix converter in which half-bridge circuits are configured by connecting bidirectional switches with modes in series, and the half-bridge circuits are arranged in parallel, and the return from the load connected to the output A single-phase to three-phase matrix converter, wherein current is controlled to flow through the bidirectional switch. The first bidirectional switch and the second bidirectional switch are connected in series and the half bridge circuit is connected. The gate terminals are arranged in the case where the bidirectional switch is a positive polarity of the voltage phase of the single-phase AC power supply. 2. The single-phase to three-phase matrix converter according to claim 1, wherein the first gate terminal and the second gate terminal are arranged in this order from the positive pole side. 3. The single-phase to three-phase matrix converter according to claim 1, wherein when the voltage phase of the single-phase AC power supply is positive, the first gate terminal of each bidirectional switch is always turned on. The single-phase-3 according to any one of claims 1 to 3, wherein when the voltage phase of the single-phase AC power supply has a negative polarity, the second gate terminal of each bidirectional switch is always on. Phase matrix converter. The PWM control of each bidirectional switch outputs only to one of the first gate terminal and the second gate terminal of each bidirectional switch according to the positive / negative polarity of the voltage phase of the single-phase AC power supply. The matrix converter according to any one of claims 1 to 4. When the single-phase AC power supply has a positive polarity voltage phase, the first gate terminal of each bidirectional switch is released from the normally-on state for a predetermined time immediately before the phase when the voltage becomes zero, and is turned off. The single-phase to three-phase matrix converter according to claim 3. When the single-phase AC power supply has a negative polarity voltage phase, the second gate terminal of each bidirectional switch is released from the always-on state for a predetermined time immediately before the phase when the voltage becomes zero, and is turned off. The single-phase to three-phase matrix converter according to claim 4. When the voltage of the single-phase AC power supply has a positive polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is equal to or less than a predetermined value, the first gate terminal of each bidirectional switch is always turned on. The single-phase to three-phase matrix converter according to claim 3, wherein the single-phase to three-phase matrix converter is released to be in an off state. When the voltage of the single-phase AC power supply has a negative polarity voltage phase and the absolute value of the voltage of the single-phase AC power supply is equal to or less than a predetermined value, the second gate terminal of each bidirectional switch is always turned on. The single-phase to three-phase matrix converter according to claim 4, wherein the single-phase to three-phase matrix converter is released. The bidirectional switch for releasing the normally-on state of the first gate terminal is any one of bidirectional switches connected in series in each half bridge circuit. Single-phase to three-phase matrix converter. The bidirectional switch for releasing the normally-on state of the second gate terminal is any one of bidirectional switches connected in series in each half bridge circuit. Single-phase to three-phase matrix converter. 11. The single-phase to three-phase matrix converter according to claim 10, wherein the bidirectional switch for canceling the normally-on state of the first gate terminal alternately performs bidirectional switches connected in series. 12. The single-phase to three-phase matrix converter according to claim 11, wherein the bidirectional switch for releasing the normally-on state of the second gate terminal alternately performs bidirectional switches connected in series. Any one of the bidirectional switches connected in series of the half-bridge circuits corresponding to the path of the return current from the load side is always kept on, and the other always-on state is released. The single-phase to three-phase matrix converter according to claim 10 or 11. 15. The single-phase to three-phase matrix converter according to claim 5, wherein the PWM control signal is generated by an individual signal from a microprocessor. 15. The single-phase to three-phase matrix according to claim 5, wherein the PWM control signal is generated by comparing a modulation factor output from a microprocessor and a carrier signal output from an external circuit. converter.

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