JP5169373B2 - Semiconductor switching device and method of using the same - Google Patents

Description

  The present invention relates to a semiconductor switching device and a method for using the semiconductor switching device, and more particularly to a semiconductor switching device including a freewheeling diode for discharging energy stored in an inductive load and a method for using the semiconductor switching device.

  A semiconductor switching device switches on and off an inductive load by using a switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET, performs step-up / step-down or generates an alternating current. Examples of the semiconductor switching device include a device including a chopper circuit and a device including an inverter such as an H-bridge circuit and a three-phase inverter. (Other examples of the semiconductor switching device are described in Patent Documents 1 to 3).

Special table 2003-536363 gazette JP 2002-199699 A Japanese Patent Laid-Open No. 04-354156

  Here, a chopper circuit will be described with reference to FIG. 10 as an example of a commonly used semiconductor switching device. In this chopper circuit, the emitter of the switching element 106 is connected to the low potential side of the DC power supply 100. Furthermore, the cathode of the freewheel diode 102 is connected to the high potential side of the DC power supply 100 and one end of the inductive load 104. The collector of the switching element 106 and the other end of the inductive load 104 are connected. Further, the anode of the freewheel diode 102 is connected to the collector of the switching element 106 and the other end of the inductive load 104.

  In such a chopper circuit, when the switching element 106 is turned on, a current flows through the path of the DC power supply 100, the inductive load 104, the switching element 106, and the DC power supply 100. Next, when the switching element 106 is turned off, the energy stored in the inductive load 104 is released through the path of the inductive load 104 and the free wheel diode 102. This current is called a reflux current and flows in the direction indicated by the arrow in FIG.

  Next, when the switching element 106 is turned on again, a current flows through the path of the DC power supply 100, the inductive load 104, the switching element 106, and the DC power supply 100 as described above.

  As described above, when the switching element 106 transitions from the off state to the on state, the freewheeling diode 102 transitions from a state in which the reflux current flows (a state in which a forward current flows) to a state in which a reverse voltage is applied. When a reverse voltage is applied immediately after a forward current is passed through the freewheeling diode 102, a current called a reverse recovery current flows in a direction opposite to the above-described reflux current. This reverse recovery current is instantaneous, and generally becomes large if the return current is large.

  Such a reverse recovery current causes high dv / dt at the timing of the transition described above. Therefore, there is a problem that switching loss and noise occur due to the reverse recovery current.

  Here, in order to solve the above-mentioned problem, it is conceivable to reduce the current capacity of the free wheel diode. For example, if the current capacity of the freewheeling diode is reduced to, for example, about 1 ampere, the reverse recovery current can be reduced, so that the above-described problem can be solved. From the viewpoint of reducing the reverse recovery current, the free wheel diode has a lower current capacity. However, in the state where the freewheeling current flows through the freewheeling diode, a sufficient current capacity of the freewheeling diode is preferable because a sufficient current needs to flow through the freewheeling diode. Therefore, it is preferable that the current capacity of the freewheel diode is large in order to sufficiently flow the return current, and it is preferable that the current capacity of the freewheel diode is small in order to suppress the reverse recovery current. Therefore, since the relationship between the two is a trade-off, there is a problem in that the return current cannot be sufficiently passed and the reverse recovery current cannot be suppressed.

  The above-described problem does not occur only in the chopper circuit shown in FIG. That is, the above-mentioned problem is a problem that appears in a semiconductor switching device including a freewheel diode in which a forward current flows through the freewheel diode and a reverse bias is applied to the freewheel diode immediately thereafter.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor switching device capable of sufficiently flowing a reflux current and suppressing a reverse recovery current and a method of using the semiconductor switching device. .

A semiconductor switching device according to the present invention is a semiconductor switching device that supplies current to an inductive load, wherein a switching element connected between a low potential side of a DC power source and one end of the inductive load, and a cathode A freewheeling diode connected to the other end of the inductive load and the high potential side of the DC power supply, and a connection between a predetermined position on the wiring to which the switching element and the inductive load are connected and the anode of the freewheeling diode A freewheeling diode whose cathode is connected to the cathode of the freewheeling diode and whose anode is connected to one end of the inductive load, and the current capacity of the freewheeling diode is the freewheeling diode. It is characterized by being larger than the current capacity of the diode .

  According to the present invention, it is possible to sufficiently flow the return current of the semiconductor switching device and to suppress the reverse recovery current.

Embodiment 1
The present embodiment relates to a chopper circuit capable of sufficiently flowing a reflux current and suppressing a reverse recovery current. FIG. 1 is a circuit diagram of a semiconductor switching device according to this embodiment. Hereinafter, FIG. 1 will be described. The switching element 16 is an IGBT (Insulated Gate Bipolar Transistor) having an emitter, a collector, and a gate. The emitter of the switching element 16 is connected to the low potential side of the DC power supply 10. On the other hand, the collector of the switching element 16 is connected to one end of the inductive load 18. The inductive load 18 is, for example, a load having a coil component such as a solenoid or a motor.

  Furthermore, the chopper circuit of this embodiment includes a freewheeling diode 12 and a freewheeling switching element 14. The freewheeling diode 12 has a current capacity of 100 amperes and a relatively large chip size. Further, like the switching element 16, the reflux switching element 14 is configured by an IGBT including an emitter, a collector, and a gate. The cathode of the dedicated reflux diode 12 is connected to the other end of the inductive load 18 and the high potential side of the DC power supply 10. On the other hand, the anode of the return diode 12 is connected to the emitter of the return switching element 14, and the collector of the return switching element 14 is connected to the collector of the switching element 16 and one end of the inductive load 18.

  The use of such a chopper circuit is to adjust the average value of the current value or voltage value of the inductive load 18. And in order to perform the above-mentioned adjustment, the switching element 16 repeats on-off with arbitrary cycles. Hereinafter, the operation (usage method) of the chopper circuit of this embodiment will be described. Here, a description will be given of a case where the switching element 16 transitions to an on state, an off state, and an on state with respect to the on / off operation repeated at an arbitrary cycle as described above.

  First, the description starts from a state where both the switching element 16 and the reflux switching element 14 are in the on state. In this state, current flows through a current path between the high potential side of the DC power supply 10, the inductive load 18, the switching element 16, and the low potential side of the DC power supply 10.

  Next, the switching element 16 is transitioned to an off state. Even when the switching element 16 transitions from the on state to the off state, the reflux switching element 14 maintains the on state. In this state, the aforementioned current path is interrupted. The energy stored in the inductive load 18 is released by returning through a closed circuit including the inductive load 18, the return switching element 14, and the return dedicated diode 12. The current flowing at this time is called a reflux current. As indicated by arrows in FIG. 1, the return current flows in the forward direction of the return dedicated diode 12.

  Next, the switching element 16 transitions from the off state to the on state. In addition, immediately before the switching element 16 transitions from the off state to the on state, the reflux switching element 14 transitions to the off state. Here, the switching element 16 is turned off at least before the reverse recovery current of the freewheeling diode 12 is generated. Then, the reflux switching element 14 once turned off is changed to the on state again after a predetermined period. The predetermined period is set to a time longer than the period during which the reverse recovery current of the freewheeling diode 12 may adversely affect the switching element 16. FIG. 2 shows a timing chart for explaining waveforms of control signals transmitted to the reflux switching element 14 and the switching element 16 in order to perform the above-described on / off switching. As shown in FIG. 2, at the timing when the switching element 16 transitions from the off state to the on state, that is, the timing when the collector current (Ic) of the switching element 16 rises, the control signal is set so that the return switching element 14 is turned off. Is transmitted.

  In FIG. 2, the off period is a period during which the switching element 14 for reflux is kept off and corresponds to the predetermined period described above. This OFF period is set so as to include the timing of the transition of the switching element 16 from the OFF state to the ON state (shown by A in FIG. 2).

  As described above, when a reverse bias (reverse voltage) is applied to the freewheel diode 102 immediately after the forward current flows to the freewheel diode 102 in FIG. 10, the reverse direction of the forward direction of the freewheel diode is reversed. A recovery current flows. The reverse recovery current instantaneously becomes a large current and is a cause of switching loss and noise. Therefore, it is desirable to suppress the reverse recovery current. Since this reverse recovery current is generally proportional to the current capacity of the freewheel diode 102, it is preferable that the current capacity of the freewheel diode 102 is low in order to suppress the reverse recovery current. On the other hand, it is preferable that the current capacity of the free wheel diode 102 is high in order to release the energy of the inductive load 104 by allowing the return current to flow easily when the switching element 16 is in the OFF state. Therefore, the chopper circuit having the configuration shown in FIG. 10 has a problem that a sufficient return current flows and a reverse recovery current cannot be suppressed.

  According to this embodiment, the above-mentioned problem can be solved. When the switching element 16 is turned off and the return current indicated by the arrow in FIG. 1 flows, the return switching element 14 is turned on. The freewheeling diode 12 of this embodiment has a large chip size and a current capacity of 100 amps, so that the energy of the inductive load 18 is sufficiently discharged. Thereafter, when the switching element 16 is turned on again, the reflux switching element 14 is turned off in order to suppress the reverse recovery current of the reflux dedicated diode 12. Therefore, the reverse recovery current, which is a harmful effect of a large current flowing instantaneously, does not flow to the switching element 16, and the adverse effects of energy loss and noise can be avoided.

  Here, especially in a chopper circuit that handles a large current, a free wheel diode having a large current capacity and a relatively large chip size is used. In such a case, the reverse recovery current of the freewheel diode was large, and problems of overvoltage surge and noise, and a problem of a decrease in energy efficiency due to energy loss were remarkable. According to this embodiment, the current capacity of the freewheeling diode is reduced. Even if it is increased, these problems can be solved since there is no concern about reverse recovery current.

  In this embodiment, an example of a chopper circuit has been described, but the present invention is not limited to this. That is, it is considered that a problem caused by the reverse recovery current occurs in a circuit having a configuration in which a forward current flows through the freewheeling diode and then a reverse bias can be applied. In addition, since the switching element for reflux is arranged between the anode side of the dedicated diode for reflux and the switching element and the above-described usage method is performed, the reverse recovery current can be suppressed in any circuit configuration. The subject of the invention is not limited to chopper circuits.

  Since the effects of the present invention can be obtained by implementing the above-described arrangement and usage of the switching elements, the switching elements 16 may be switching elements other than IGBTs. Further, the reflux switching element 14 is not limited to the IGBT. The switching element 16 and the reflux switching element 14 may be appropriately determined according to the current conducted to the circuit and the voltage applied to each element.

  Similarly, the description that the current capacity of the freewheeling diode 12 of this embodiment is 100 amperes is not limited to this. The effect of the present invention can be obtained if the current capacity of the freewheeling diode 12 is appropriately determined so as to satisfy a value necessary for the freewheeling current to flow.

  In the present embodiment, the reflux switching element 14 is turned off immediately before the switching element 16 transitions from the off state to the on state, but the present invention is not limited to this. That is, when the switching element 16 is transitioned from the off state to the on state, the reflux switching element needs to be surely in the off state. Here, for example, when a MOSFET capable of high-speed switching is used as the reflux switching element 14 as in the present embodiment, the switching element 16 is switched from the OFF state to the ON state, and at the same time, the reflux switching element 14 is turned off. Even in the state, the effect of suppressing the reverse recovery current can be obtained. Therefore, the effect of the present invention can be obtained if the timing at which the return switching element is turned off is appropriately determined so that the reverse recovery current can be suppressed in consideration of the response speed of the return switching element 16 and the like.

  Further, the control signal transmitted to the reflux switching element 14 for switching on and off the reflux switching element 14 of the present embodiment may be determined from the control signal to the switching element 16. More specifically, it is conceivable to detect that the switching element 16 has been switched from the off state to the on state and simultaneously transmit a control command to be turned off to the reflux switching element 14.

Embodiment 2
The present embodiment relates to a chopper circuit capable of sufficiently flowing a return current and suppressing a reverse recovery current, and more particularly to a chopper circuit including a plurality of diodes in a path through which the return current flows.

  The configuration of this embodiment will be described with reference to FIG. In FIG. 3, the same reference numerals as those in FIG. 1 are assigned to the same components as those in FIG. Hereinafter, the difference when compared with FIG. 1 of FIG. 3 will be described. The chopper circuit shown in FIG. 3 includes a free wheel diode 20, and the return switching element 15 includes an IGBT including an emitter, a collector, and a gate. The cathode of the freewheel diode 20 is connected to the cathode of the freewheeling diode 12 and the other end of the inductive load 18. On the other hand, the anode of the freewheel diode 20 is connected to the collector of the switching element 16 and one end of the inductive load 18 and the collector of the return switching element 15, and the emitter of the return switching element 15 is connected to the anode of the return dedicated diode 12. The

  The free wheel diode 20 has a current capacity of 1 ampere, which is a small chip compared to the freewheeling diode 12 which is a large chip of 100 amperes.

  The freewheeling diode 12, the freewheeling switching element 15, and the freewheel diode 20 are circuits that flow (circulate) the freewheeling current, and are therefore referred to as the freewheeling circuit 24.

  The switching element 16 and the reflux switching element 15 of the present embodiment perform switching similar to the switching element 16 and the reflux switching element 14 of the first embodiment, respectively. In the present embodiment, the return current flows through two paths of the return dedicated diode 12 and the freewheel diode 20. In FIG. 3, the reflux current passing through the reflux diode 12 is represented as the reflux current 28. Further, the reflux current passing through the free wheel diode 20 is represented as a reflux current 26.

  After the return current flows, the return dedicated diode 12 is turned off and the switching element 16 is turned on as in the first embodiment. At this time, a reverse recovery current is generated from the freewheel diode 20. The reverse recovery current is shown as reverse recovery current 30 in FIG. However, since the current capacity of the freewheel diode 20 is 1 ampere, the reverse recovery current is negligible or negligible. Therefore, even if it is a chopper circuit provided with the structure of this embodiment, the switching element 16 does not receive the bad influence of switching loss or noise.

  The feature of this embodiment is the reflux circuit 24. That is, when a plurality of diodes are arranged on the path through which the return current flows as in the present embodiment, the return switching element 15 is provided for the return-only diode 12 that exclusively carries the return current by increasing the current capacity. Deploy. The reflux switching element 15 is connected between the anode of the reflux diode 12 and the switching element 16. This suppresses reverse recovery current. On the other hand, since the freewheeling diode 20 on the path through which the return current flows is not provided with the switching element for switching between the freewheeling diode 20 and the switching element 16, the current capacity is reduced and the reverse recovery current is suppressed. By doing in this way, it is possible to make both the return current flow sufficiently and to suppress the reverse recovery current.

  In the present embodiment, the current capacity of the freewheeling diode 12 is 100 amperes and the current capacity of the freewheel diode 20 is 1 ampere, but the present invention is not limited to this. That is, the current capacity of the freewheeling diode 12 is high enough to allow the freewheeling current to flow sufficiently, and if the current capacity of the freewheeling diode is low enough to allow the reverse recovery current, the current capacity can be obtained. It is not limited to the above values. An essential requirement for obtaining the effect of the present embodiment is that the current capacity of the freewheeling diode 12 is larger than the current capacity of the freewheel diode 20. That is, if the current capacity of the freewheeling diode 12 is made larger than the current capacity of the freewheel diode 20, the freewheeling diode can sufficiently flow the freewheeling current, and the reverse diode side is cut off during reverse recovery. The recovery current can be effectively reduced.

  In addition, the cathode of the freewheel diode 20 in this embodiment is connected to the cathode of the freewheeling diode 12, but the connection destination is the anode of the freewheeling diode 12 (the emitter of the freewheeling switching element 15) side. May be replaced. That is, even if the freewheel diode is connected in parallel with the freewheeling switching element 15 and in series with the freewheeling diode 12, the same effect as in the present embodiment can be obtained. It is possible to use a voltage-resistant element.

  Since the freewheeling diode 20 may be used as the freewheeling switching element 15, a low withstand voltage element may be used. In this embodiment, as the freewheeling switching element 15, a MOSFET (Metal-Oxide-Semiconductor-FET) is used instead of the IGBT. May be used, and thereby the on-voltage characteristics can be lowered. Since the MOSFET can perform high-speed switching, it is preferable for accurately setting the off-period of the above-described reflux switching element 14. Furthermore, since the reverse recovery current does not occur in the freewheeling diode 12, the generated loss can be reduced even in the series connection by lowering the on-voltage characteristics. Thus, by using MOSFET, the loss of a semiconductor switching device can be reduced.

  The reflux circuit 24 described with reference to FIG. 3 in the present embodiment can be replaced with the reflux circuit 40 shown in FIG. The chopper circuit of FIG. 4 is the same as the configuration of FIG. 3 except that the reflux circuit 24 of FIG. The reflux circuit 40 includes a reverse blocking switching element 44. The reverse blocking switching element 44 has an emitter connected to the high potential side of the DC power supply 10 and the other end of the inductive load 18. The collector of the reverse blocking switching element 44 is connected to one end of the inductive load 18 and the collector of the switching element 16. Here, the structure of the reverse blocking switching element adopts a well-known structure, and detailed description thereof is omitted.

  The reverse blocking switching element 44 is equivalent to a switching element and a diode connected in series. That is, the reverse blocking switching element 44 of the present embodiment can be regarded as a combination of the freewheeling diode 12 and the freewheeling switching element 15 in FIG. Therefore, compared with the case where the switching element and the diode are manufactured on separate chips, the element can be made into one chip and the apparatus can be downsized.

  Here, after the reverse blocking switching element 44 of the chopper circuit shown in FIG. 4 is always turned on, the waveform (current-time) of the reflux circuit 40 when the switching element 16 is repeatedly turned on and off from the off state to the on state. FIG. 5 shows a graph in which characteristics) are recorded. On the other hand, FIG. 6 shows the same waveform when the reverse blocking switching element 44 is turned off during the transition of the switching element 16 from the off state to the on state.

  In FIG. 5, the reverse recovery current can be confirmed, and there is a concern about switching loss and noise. However, it can be confirmed in FIG. 6 that the reverse recovery current is suppressed. Such an effect is commonly obtained in the semiconductor switching device of the present invention. As described above, the reflux circuit which is a characteristic part of the present embodiment can be variously modified while obtaining the effects of the present invention.

Embodiment 3
The present embodiment relates to an inverter that can sufficiently flow a return current and suppress a reverse recovery current, and more particularly to a bridge circuit, and relates to a bridge circuit that includes a plurality of diodes in a path through which the return current flows. Hereinafter, the bridge circuit of the present embodiment will be described with reference to FIG.

  The bridge circuit of this embodiment includes an IGBT 52 whose collector is connected to the high potential side of the DC power supply 50. The IGBT 52 is a switching element that constitutes the upper arm, and is connected at its emitter to the collector of the IGBT 54 that constitutes the lower arm. The emitter of the IGBT 54 is connected to the low potential side of the DC power supply 50. Furthermore, an arm (referred to as a second arm) different from the above-described arm (referred to as a first arm) includes an IGBT 56 and an IGBT 58. The collector of IGBT 56 is connected to the collector of IGBT 52 and the high voltage side of DC power supply 50. Further, the emitter of the IGBT 56 and the collector of the IGBT 58 are connected. The emitter of the IGBT 58 is connected to the emitter of the IGBT 54 and the low potential side of the DC power supply 50.

A free wheel diode is connected to each of the IGBTs described above. For example, the emitter of the IGBT 52 and the anode of the free wheel diode 62 are connected, and the collector of the IGBT 52 and the cathode of the free wheel diode 62 are connected. The same applies to the freewheel diodes 64, 66, and 68 in FIG. Furthermore, a freewheeling diode 70 and a freewheeling switching element 72 are connected to the upper arm (IGBT 52) of the first arm of this embodiment. That is, the cathode of the freewheeling diode 70 is connected to the collector of the IGBT 52. The anode of the dedicated reflux diode 70 is connected to the emitter of the reflux switching element 72. The collector of the reflux switching element 72 is connected to the emitter of the IGBT 52. In the present embodiment, the reflux switching element 72 is an IGBT, but may be a MOSFET or the like.
As for the IGBTs 54, 56, and 58, similarly to the IGBT 52, a freewheeling diode and a freewheeling switching element are connected.

  Here, the current capacity of the freewheeling diode 70 is 100 amperes, and the current capacity of the freewheel diode 62 is 1 ampere.

  One end of the inductive load 60 is connected to the collector of the return switching element 72, the emitter of the IGBT 52, and the collector of the IGBT 54. The other end of the inductive load 60 is connected to the emitter of the IGBT 56 and the collector of the IGBT 58.

  Hereinafter, a method of using the bridge circuit of the present embodiment will be described. First, the IGBT 56 and the IGBT 54 are turned on so that a current flows from the other end of the inductive load 60 toward the one end. At this time, both the IGBT 52 and the IGBT 58 are in an off state, but the reflux switching element 72 is in an on state. Next, the IGBT 54 is switched to an off state. The energy of the inductive load 60 is released through the path of the inductive load 60, the switching element 72 for reflux, the dedicated diode 70 for reflux, and the IGBT 56. In addition, although the current capacity is as small as 1 ampere, the freewheel diode 62 also serves as a return current path (indicated by an arrow in FIG. 7).

  Next, the IGBT 54 is turned on again. At this time, the control command is transmitted so that the reflux switching element 72 is in the OFF state. Therefore, the reverse recovery current from the freewheeling diode 70 is not generated and the IGBT 54 is not adversely affected. Further, although a reverse recovery current can flow from the free wheel diode 62, the current capacity of the free wheel diode 62 is determined to be as low as 1 ampere. Therefore, the reverse recovery current is weak and has no harmful effect. As described above, according to the configuration and the usage method of the present embodiment, it is possible to sufficiently flow the reflux current and suppress the reverse recovery current.

The feature of the present embodiment is that the return current can be passed by a diode having a large current capacity (100 amperes in this embodiment), and the reverse recovery current is suppressed by separating the diode having the large current capacity from the circuit. . Therefore, the switching element for reflux is not limited to the MOSFET, and the IGBTs 52, 54, 56, and 58 are not limited to the IGBT and may be other switching elements.

  Similarly, the current capacity of the freewheeling diode is 100 amperes, and the current capacity of the freewheeling diode is 1 ampere. The above-described current capacity is an example, and may be determined as appropriate in consideration of the electrical characteristics of the semiconductor switching device. However, it is an essential requirement for obtaining the effect of the present invention that the current capacity of the freewheeling diode is larger than the current capacity of the freewheel diode.

  The present invention can be applied to various switching devices. For example, the present invention can be applied to a three-phase inverter that drives a motor 98 as shown in FIG. In FIG. 8, free wheel diodes 79, 80, 81, 82, 83, 84 are connected in parallel to the IGBTs 73, 74, 75, 76, 77, 78. The above-described IGBTs are connected to switching elements 85, 87, 89, 91, 93, 95 for reflux and dedicated diodes 86, 88, 90, 92, 94, 96 for reflux. The current capacity of the freewheeling diode is larger than that of the freewheel diode. Also for such a three-phase inverter, the effect of the present invention can be obtained by allowing the return current to flow through the return-only diode and turning off the return switching element during the period in which the reverse recovery current can occur.

  In the three-phase inverter shown in FIG. 8 described above, a freewheeling diode and a freewheeling switching element (both are collectively referred to as a freewheeling circuit) are incorporated in the same package as the inverter portion. However, for example, as shown in FIG. 9, the effect of the present invention is not lost even if the reflux circuit 99 is formed in a separate package from the inverter unit 101. The connection at this time is as shown in FIG. In this case, the inverter unit 101 that does not have the freewheeling diode remains small, and the degree of freedom in layout is improved. The freewheeling diode is provided on the freewheeling circuit 99 side in addition to the freewheeling switching element and the freewheeling diode. However, when the wiring between the freewheeling circuit 99 and the inverter unit 101 can be made sufficiently short, When the switching element for reflux is employed, it is not always necessary to incorporate it.

2A and 2B illustrate a semiconductor switching device in Embodiment 1 and a method for using the semiconductor switching device. 3A and 3B illustrate a method for using the semiconductor switching device of Embodiment 1. 3A and 3B illustrate a semiconductor switching device according to Embodiment 2 and a method for using the semiconductor switching device. 3A and 3B illustrate a semiconductor switching device according to Embodiment 2 and a method for using the semiconductor switching device. The figure explaining the bad effect of a reverse recovery current. The figure explaining the effect of reverse recovery current suppression. 4A and 4B illustrate a semiconductor switching device according to Embodiment 3 and a method for using the semiconductor switching device. The figure explaining the example which applied this invention to the three-phase inverter. The figure explaining the structure which used the return circuit as the external attachment of the inverter part. The figure for demonstrating a subject.

Explanation of symbols

12 Diode for exclusive use of reflux 14 Switching element for reflux 16 Switching element 18 Inductive load 10 DC power supply 44 Reverse blocking switching element

Claims (8)

A semiconductor switching device for supplying current to an inductive load,
A switching element connected between a low potential side of a DC power source and one end of the inductive load;
A freewheeling diode whose cathode is connected to the other end of the inductive load and the high potential side of the DC power supply;
A switching element for return connected between a predetermined position on the wiring to which the switching element and the inductive load are connected and an anode of the return dedicated diode ;
A free wheel diode having a cathode connected to the cathode of the freewheeling diode and an anode connected to one end of the inductive load ;
The semiconductor switching device according to claim 1, wherein a current capacity of the freewheeling diode is larger than a current capacity of the freewheel diode .   The semiconductor switching device according to claim 1, wherein the return dedicated diode and the return switching element are formed of reverse blocking switching elements. A semiconductor switching device for supplying current to an inductive load,
An upper arm switching element whose collector is connected to the high potential side of the DC power supply and one end of the inductive load;
A lower arm switching element having a collector connected to an emitter of the upper arm switching element and the other end of the inductive load, and an emitter connected to a low potential side of the DC power supply;
A free-wheeling diode whose cathode is connected to the collector of the upper arm switching element and the one end of the inductive load;
A switching element for return connected between a predetermined position on the wiring to which the other end of the inductive load and the collector of the lower arm switching element are connected, and an anode of the return dedicated diode;
A freewheeling diode having a cathode connected to the collector of the upper arm switching element and an anode connected to the emitter of the upper arm switching element,
The semiconductor switching device according to claim 1, wherein a current capacity of the freewheeling diode is larger than a current capacity of the freewheel diode . Semiconductor switching device according to any one of claims 1 to 3, characterized in that the current capacity of the freewheeling diode is 1 amperes. The semiconductor switching device according to claim 1, wherein the reflux switching element is a MOS field effect transistor. The reflux dedicated diode and the freewheeling switching element is a semiconductor switching device according to any one of claims 1 to 5, characterized in that mounted on the switching element and the same package. The reflux dedicated diode and the freewheeling switching element is a semiconductor switching device according to any one of claims 1 to 5, characterized in that it is formed on a substrate different from the switching element. A method of using the semiconductor switching device according to claim 1,
Wherein after energizing the inductive load switching elements as one, and the flow of the return current in the return-only diode and the freewheeling diode of the switching element off Toshikatsu the wheeling switching element as one,
A method of using a semiconductor switching device in which the switching element for reflux is turned off simultaneously with or before the switching element is turned on again .

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