Power conversion device

Abstract

A power conversion device 1 comprises: a switching element 11ula; a first current terminal T1 which is connected to the drain of the switching element 11ula and has an inductance component Ld; a second current terminal T2 which is connected to the source of the switching element 11ula and has an inductance component Ls; a coil part 23a which is a conductive wire provided so as to magnetically couple with both a first current path 29 from the first current terminal T1 to the drain and a second current path 30 from the source to the second current terminal T2 and is disposed between the first current terminal T1 and the second current terminal T2; and a driver circuit 13ul having a drive circuit 25 which generates a drive signal Vg and supplies the drive signal Vg to the gate of the switching element 11ula and an adjustment circuit 27 which adjusts the drive signal Vg on the basis of a voltage generated between both ends of the coil part 23a.

Description

Power Conversion Equipment The present disclosure relates to a power conversion device. A driving circuit is used to drive a switching element built into an inverter circuit or the like. The following Patent Document 1 discloses a semiconductor device having a switching element, a first inductance component through which a drain current flows, and a second inductance component magnetically coupled to the first inductance component. In this semiconductor device, a feedback voltage is generated in the second inductance component in accordance with a change in the drain current in the first inductance component. Then, the feedback voltage is added to a conversion command voltage and then applied to a gate terminal of the switching element. JP 2022-61798 A In the semiconductor device described above, it is desirable to increase the detection voltage generated by the second inductance component in order to sufficiently reduce the switching loss. If the inductance of the first inductance component is increased in order to increase the detection voltage, the surge voltage between the drain and source of the switching element tends to increase. Furthermore, if the inductance of the second inductance component is increased in order to increase the detection voltage, the inductance that affects the current flowing through the gate of the switching element increases, which may affect the control of the switching operation of the switching element. Therefore, one aspect of an embodiment has been made in consideration of such problems, and an object of the invention is to provide a power conversion device that can achieve a reduction in surge voltage and switching loss while maintaining a switching speed. A power conversion device according to one aspect of the present disclosure includes a switching element accommodated in an element package, the switching element having a control terminal, a first current terminal into which a main current flows, and a second current terminal from which the main current flows out, a first wiring portion connected to the first current terminal of the switching element and having an inductance component, a second wiring portion connected to the second current terminal of the switching element and having an inductance component, a coil portion which is a conductor arranged to be magnetically coupled to both the first current path from the first wiring portion to the first current terminal and the second current path from the second current terminal to the second wiring portion, a drive circuit which generates a drive signal and supplies it to the control terminal of the switching element, and an adjustment circuit which adjusts the drive signal based on the voltage generated across both ends of the coil portion. In this power conversion device, the coil section is provided so as to be magnetically coupled to both the first current path through which the main current flows into the switching element and the second current path through which the main current flows out of the switching element, and is therefore efficiently magnetically coupled to the inductance component through which the main current flows. This makes it possible to increase the detection voltage, which is the voltage generated by the coil section due to the time change in the main current, without increasing the inductance through which the main current flows and the inductance of the coil section magnetically coupled thereto. As a result, it is possible to reduce the surge voltage and the switching loss while maintaining the switching speed of the switching element. According to the present disclosure, it is possible to achieve a reduction in surge voltage and switching loss while maintaining switching speed. Fig. 1 is a circuit diagram showing a schematic configuration of a power conversion device according to an embodiment. Fig. 2 is a circuit diagram showing a schematic configuration of a switching circuit section and a driver circuit shown in Fig. 1. Fig. 3 is a plan view showing the arrangement of the switching elements and the coil section shown in Fig. 2. Fig. 4(a) is a perspective view showing an example of mounting the switching elements and the coil section, and Fig. 4(b) is a circuit diagram of the switching elements shown in Fig. 4(a). Fig. 5 is a diagram showing the configuration of a switching circuit section and a driver circuit according to a first modified example. Fig. 6 is a diagram showing the configuration of a switching circuit section and a driver circuit according to a second modified example. Hereinafter, a power conversion device according to an embodiment will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicated description will be omitted. A circuit configuration of a power conversion device according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the circuit configuration of a power conversion device according to an embodiment. The power conversion device 1 shown in Fig. 1 is an inverter device that converts DC power supplied from an external power source 2 into AC power capable of driving a motor 3. The power conversion device 1 is mounted on, for example, a vehicle. The external power supply 2 is a DC power supply, for example, a storage battery. The power conversion device 1 has an input terminal 1a and an input terminal 1b. The input terminal 1a is connected to a positive terminal of the external power supply 2, and the input terminal 1b is connected to a negative terminal of the external power supply 2 and a reference potential V0. The motor 3 has three-phase coils 3u, 3v, and 3w. The coils 3u, 3v, and 3w are connected, for example, in a Y-connection. The motor 3 rotates when a current flows through the coils 3u, 3v, and 3w in a predetermined pattern. The connection of the coils 3u, 3v, and 3w is not limited to a Y-connection, and may be a delta connection. The power conversion device 1 includes switching circuit units 11uh, 11ul, 11vh, 11vl, 11wh, and 11wl (hereinafter referred to as "switching circuit units 11uh to 11wl"), driver circuits (circuit units) 13uh, 13ul, 13vh, 13vl, 13wh, and 13wl (hereinafter referred to as "driver circuits 13uh to 13wl"), a capacitor 14, and a control device 15. Each of the switching circuit units 11uh to 11wl includes a plurality of built-in switching elements. In this embodiment, an n-channel metal oxide semiconductor field effect transistor (MOSFET) is exemplified as the switching element included in each of the switching circuit units 11uh to 11wl. For example, the switching element is a SiC MOSFET. The switching element may be a p-channel MOSFET. The switching element may be an insulated gate bipolar transistor (IGBT) or a GaN HEMT. The switching circuit unit 11uh is a switching circuit unit of the upper arm of the U phase. The switching circuit unit 11ul is a switching circuit unit of the lower arm of the U phase. The switching circuit unit 11uh and the switching circuit unit 11ul are connected in series between the input terminal 1a and the input terminal 1b, and each has a first current terminal (drain terminal) T1 and a second current terminal (power source terminal) T2. Specifically, the first current terminal T1 of the switching element included in the switching circuit unit 11uh is connected to the input terminal 1a. The second current terminal T2 of the switching element included in the switching circuit unit 11uh and the first current terminal T1 of the switching element included in the switching circuit unit 11ul are connected to each other and connected to the coil 3u. The second current terminal T2 of the switching element included in the switching circuit unit 11ul is connected to the input terminal 1b. The switching circuit unit 11vh is a switching circuit unit of an upper arm of the V phase. The switching circuit unit 11vl is a switching circuit unit of a lower arm of the V phase. The switching circuit unit 11vh and the switching circuit unit 11vl are connected in series between the input terminal 1a and the input terminal 1b, and each has a first current terminal (drain terminal) T1 and a second current terminal (power source terminal) T2. Specifically, the first current terminal T1 of the switching element included in the switching circuit unit 11vh is connected to the input terminal 1a. The second current terminal T2 of the switching element included in the switching circuit unit 11vh and the first current terminal T1 of the switching element included in the switching circuit unit 11vl are connected to each other and connected to the coil 3v. The second current terminal T2 of the switching element included in the switching circuit unit 11vl is connected to the input terminal 1b. The switching circuit unit 11wh is a switching circuit unit of an upper arm of the W phase. The switching circuit unit 11wl is a switching circuit unit of a lower arm of the W phase. The switching circuit unit 11wh and the switching circuit unit 11wl are connected in series between the input terminal 1a and the input terminal 1b, and each has a first current terminal (drain terminal) T1 and a second current terminal (power source terminal) T2. Specifically, the first current terminal T1 of the switching element included in the switching circuit unit 11wh is connected to the input terminal 1a. The second current terminal T2 of the switching element included in the switching circuit unit 11wh and the first current terminal T1 of the switching element included in the switching circuit unit 11wl are connected to each other and connected to the coil 3w. The second current terminal T2 of the switching element included in the switching circuit unit 11wl is connected to the input terminal 1b. A gate voltage (drive signal) Vg is applied from the driver circuits 13uh to 13wl to the gates (control terminals) of the switching elements included in the switching circuit units 11uh to 11wl. When the gate voltage Vg is applied to the gates, a main current (source current) Is flows between the first current terminal T1 and the second current terminal T2 in each switching element. Specifically, when the gate-source voltage becomes larger than the threshold voltage of the switching element, the switching element turns on, and a main current Is corresponding to the difference between the gate-source voltage and the threshold voltage flows between the first current terminal T1 and the second current terminal T2. Each of the driver circuits 13uh to 13wl is an active gate driver circuit, and changes the gate voltage Vg based on an external command voltage Vref input from the control device 15 and a detection voltage that is a voltage generated by a change in the main current Is. The details of the driver circuits will be described later. The capacitor 14 is charged by the external power supply 2 and is used to suppress voltage fluctuations that occur when the power conversion device 1 operates. The capacitor 14 is connected in parallel to the external power supply 2. Specifically, one end of the capacitor 14 is connected to the input terminal 1a, and the other end of the capacitor 14 is connected to the input terminal 1b. As the capacitor 14, for example, a capacitor bank including a plurality of electrolytic capacitors is used. The control device 15 is a circuit that generates an external command voltage Vref for driving the switching circuit units 11uh to 11wl. The control device 15 determines a target current to flow through the motor 3 based on an external command (e.g., a required rotation speed), and derives an external command voltage Vref for flowing the target current. In this embodiment, the control device 15 derives the external command voltage Vref for each of the switching circuit units 11uh to 11wl, and supplies the external command voltage Vref to each of the driver circuits 13uh to 13wl. Next, the driver circuits 13uh to 13wl will be described in detail with reference to Fig. 2. Fig. 2 is a circuit diagram that shows a schematic diagram of the switching circuit section and the driver circuit shown in Fig. 1. Here, each of the driver circuits 13uh to 13wl has basically the same configuration, and each of the switching circuit sections 11uh to 11wl has basically the same configuration. Therefore, the driver circuit 13ul and the switching circuit section 11ul will be described in detail. As shown in FIG. 2, the switching circuit unit 11ul includes two switching elements, a switching element 11ula and a switching element 11ulb. The switching element 11ula has a first wiring portion 21a into which the main current flows and a second wiring portion 22a from which the main current flows. A part of one end of the first wiring portion 21a constitutes the first current terminal T1 of the switching element 11ula, and the other end is connected to the input terminal 1a via the switching circuit unit 11uh. A part of one end of the second wiring portion 22a constitutes the second current terminal T2 of the switching element 11ula, and the other end is connected to the input terminal 1b. The first wiring portion 21a has an inductance component (floating inductance) Ld, and the second wiring portion 22a has an inductance component (floating inductance) Ls. The switching element 11ula also has a freewheeling diode Dula connected in parallel therewith. The cathode of the freewheeling diode Dula is connected to the first current terminal T1 of the switching element 11ula, and the anode of the freewheeling diode Dula is connected to the second current terminal T2 of the switching element 11ula. The switching element 11ulb is connected in parallel with the switching element 11ula. The switching element 11ulb has a first wiring portion 21b, a second wiring portion 22b, and a free wheel diode Dulb, similar to the switching element 11ula. In this manner, the switching circuit portion 11ul is formed by the two switching elements 11ula and 11ulb connected in parallel, thereby reducing the conduction loss in the MOSFET. The driver circuit 13ul includes an adjustment circuit 27 having coils 23a and 23b, resistors 24a and 24b, and a wiring section 26, and a drive circuit 25. The drive circuit 25 generates a drive signal Vg for driving the switching elements 11ula and 11ulb based on an external command voltage Vref, and supplies the drive signal Vg to the gates of the switching elements 11ula and 11ulb. The adjustment circuit 27 is a circuit for adjusting the drive signal Vg supplied to the gates of the two switching elements 11ula and 11ulb to suppress imbalance of the main current (source current Is) flowing through each of the switching elements 11ula and 11ulb. The coil portion 23a is an element that is magnetically coupled to the inductance component Ld of the first wiring portion 21a and the inductance component Ls of the second wiring portion 22a, and generates a voltage at both ends thereof according to the change in the main current Is in the inductance component Ld and the change in the main current Is in the inductance component Ls. One end of the coil portion 23a is connected to the gate of the switching element 11ula, and the other end is connected to an output terminal 25a for outputting a drive signal Vg of the drive circuit 25 via a resistor 24a. One end of the wiring portion 26 is connected to the source of the switching element 11ula, and the other end is connected to a reference potential terminal 25b for applying a reference potential of the drive circuit 25. That is, the driver circuit 13ul has a configuration in which the coil portion 23a and the drive circuit 25 are connected in series between the gate and source of the switching element 11ula. Similarly, the coil portion 23b is magnetically coupled to the inductance component Ld of the first wiring portion 21b and the inductance component Ls of the second wiring portion 22b. One end of the coil portion 23b is connected to the gate of the switching element 11ulb, and the other end is connected to an output terminal 25a for outputting a drive signal Vg of the drive circuit 25 via a resistor 24b. One end of the wiring portion 26 is also connected to the source of the switching element 11ulb. That is, the driver circuit 13ul has a configuration in which the coil portion 23b and the drive circuit 25 are connected in series between the gate and source of the switching element 11ulb. In the driver circuit 13ul having the above configuration, when the source current Is in the inductance component Ld of the first wiring portion 21a and the inductance component Ls of the second wiring portion 22a is large, the detection voltage becomes large, so the driver circuit 13ul applies the drive signal Vg from which the large detection voltage is subtracted to the gate of the switching element 11ula. On the other hand, when the source current Is in the inductance component Ld of the first wiring portion 21a and the inductance component Ls of the second wiring portion 22a is small, the detection voltage becomes small, so the driver circuit 13ul applies the drive signal Vg from which the small detection voltage is subtracted, that is, the gate voltage (drive signal Vg) with a relatively small subtraction to the gate of the switching element 11ula. By such an operation, the driver circuit 13ul adjusts the gate voltage applied to the gate of the switching element 11ula. Similarly, the driver circuit 13ul adjusts the gate voltage applied to the gate of the switching element 11ulb in response to fluctuations in the source current Is in the first wiring portion 21b and the second wiring portion 22b. In the switching elements 11ula and 11ulb, when the gate voltage is lowered, the source current Is is reduced. In addition, when the source current Is of one of the switching elements 11ula and 11ulb connected in parallel is reduced, the source current Is of the other element increases accordingly. Therefore, with the above configuration, it is possible to suppress imbalance in the source current Is flowing through the switching elements 11ula and 11ulb. The positional relationship between the switching element 11ula and the coil portion 23a will be described in detail with reference to Figures 3 and 4. Figure 3 is a plan view showing the positional relationship between the switching element 11ula and the coil portion 23a. Figure 4(a) is a perspective view showing an example of mounting the switching element 11ula and the coil portion 23a, and Figure 4(b) is a circuit diagram of the switching element 11ula shown in Figure 4(a). The positional relationship between the switching element 11ulb and the coil portion 23b is similar to that between the switching element 11ula and the coil portion 23a, so a description thereof will be omitted. As shown in FIG. 3, in this embodiment, a four-terminal package in which a switching element body 28a is accommodated in an element package PKG is used as the switching element 11ula. That is, the switching element 11ula has a first current terminal (drain terminal) T1, a second current terminal (power source terminal) T2, a driver source terminal T3, and a gate terminal T4, which are long conductive terminals extending in one direction from an end of the element package PKG. The first current terminal T1 is connected to the drain of the switching element body 28a in the element package PKG, and also constitutes a first wiring part 21a having an inductance component. The second current terminal T2 is connected to the source of the switching element body 28a in the element package PKG, and also constitutes a second wiring part 22a. The gate terminal T4 is connected to the gate of the switching element body 28a in the element package PKG. The driver source terminal T3 is connected to the source of the switching element body 28a in the element package PKG. In the switching element 11ula, a first current path 29 is formed from the first wiring portion 21a to the first current terminal T1, through which the main current flows. That is, the first current path 29 includes both the wiring portion (inductance component) of the first current terminal T1 and the first wiring portion 21a in the element package PKG other than the wiring portion. In addition, in the switching element 11ula, a second current path 30 is formed from the second current terminal T2 to the second wiring portion 22a, through which the main current flows. That is, the second current path 30 includes both the wiring portion (inductance component) of the second current terminal T2 and the second wiring portion 22a other than the wiring portion. As shown in FIG. 4A, the switching element 11ula is mounted on the circuit board 10 on which the driver circuits 13uh-13wl are mounted so that the element package PKG stands upright while being supported by the terminals T1-T4. With the switching element 11ula mounted on the circuit board 10, the first current terminal T1 is connected to the wiring pattern P1 on the circuit board 10. The second current terminal T2 is connected to the wiring pattern P2 on the circuit board 10 and is connected to the input terminal 1b via the wiring pattern P2. The gate terminal T4 is connected to the wiring pattern P4 on the circuit board 10 and is connected to the coil portion 23a via the wiring pattern P4. The driver source terminal T3 is connected to the wiring pattern P3 on the circuit board 10 and is connected to the reference potential terminal 25b of the drive circuit 25 via the wiring pattern P3. 3 and 4A, the coil portion 23a is disposed between the first current path 29 on the first current terminal T1 and the second current path 30 on the second current terminal T2, and is configured to be magnetically coupled to both the first current path 29 and the second current path 30, and to be magnetically coupled to the inductance component Ld of the first current terminal T1 and the inductance component Ls of the second current terminal T2. Here, "disposed between the first current path 29 on the first current terminal T1 and the second current path 30 on the second current terminal T2" has the following meaning. When the direction in which the first current terminal T1 and the second current terminal T2 extend is defined as the X-axis direction, and the direction perpendicular to the X-axis direction connecting the center of the first current terminal T1 and the center of the second current terminal T2 is defined as the Y-axis direction, at least a part of the coil portion 23a is disposed so as to overlap the gap between the first current terminal T1 and the second current terminal T2 when viewed from a direction perpendicular to the XY plane. In detail, the coil portion 23a is composed of a winding (conductor) 32a wound in a circular shape and an iron core 31a inserted inside the winding 32a. The winding 32a and the iron core 31a are fixed to both the first current terminal T1 and the second current terminal T2 using an insulating adhesive or an insulating member (e.g., a resin molded member). One end of the winding 32a is connected to a wiring pattern P5 on the circuit board 10 and is connected to the resistor 24a via the wiring pattern P5. The other end of the winding 32a is connected to a wiring pattern P6 on the circuit board 10 and is connected to the gate terminal T4 via the wiring pattern P6. In the power conversion device 1 described above, the coil section 23a is provided so as to be magnetically coupled to both the first current path 29 through which the main current flows into the switching element 11ula and the second current path 30 through which the main current flows out from the switching element 11ula, so that the coil section 23a is efficiently magnetically coupled to the inductance components Ld and Ls through which the main current flows. This makes it possible to increase the detection voltage, which is the voltage generated by the coil section 23a due to the time change of the main current, without increasing the inductance through which the main current flows and the inductance of the coil section 23a that is magnetically coupled thereto. As a result, it is possible to reduce the surge voltage and the switching loss while maintaining the switching speed of the switching element 11ula. In other words, if the inductance of the path through which the main current Is flows is increased, the surge voltage between the drain and source of the switching element will increase. Also, if the inductance of the coil section 23a is increased, the leakage inductance increases and the operation of the driver circuit 13ul will become slower. In the power conversion device 1, it is possible to suppress imbalance of main currents among a plurality of switching elements without causing a decrease in surge voltage and a decrease in the operating speed of the driver circuit 13ul. In this embodiment, the coil portion 23a is fixed to both the first current terminal T1 and the second current terminal T2. In this case, the first current path 29 and the second current path 30 through which the main current flows can be stably brought close to the coil portion 23a, and the distance between the first current path 29 and the second current path 30 and the coil portion 23a can be stabilized. As a result, the inductance components Ld and Ls through which the main current flows and the coil portion 23a are efficiently and stably magnetically coupled. Specifically, since the coil portion 23a is integrated with the first current terminal T1 and the second current terminal T2, it is not necessary to adjust the positional relationship between the coil portion 23a and the first current path 29 and the second current path 30, compared to a case in which the coil portion 23a is not fixed to the first current terminal T1 and the second current terminal T2, and the coil portion 23a can be easily provided at a position where it is magnetically coupled to the first current path 29 and the second current path 30. As a result, it is possible to further reduce switching loss. In this embodiment, the coil portion 23a is a winding 32a, which is a conductor wound in a circular shape, and has an iron core 31a inserted inside the winding 32a. In this case, the iron core 31a reduces the magnetic resistance and increases the coupling coefficient, so that the inductance components Ld and Ls through which the main current flows and the coil portion 23a are magnetically coupled even stronger. The stronger magnetic coupling can increase the detection voltage generated in the coil portion 23a due to the time change of the main current. As a result, it is possible to further reduce switching loss. In this embodiment, the coil portion 23a is connected in series between the drive circuit 25 and the gate of the switching element 11ula to form an adjustment circuit 27. In this case, it is possible to reduce switching loss while maintaining the switching speed. Although one embodiment of the present disclosure has been described in detail above, the power conversion device according to the present disclosure is not limited to the above embodiment. In the present embodiment, each of the switching circuit units 11uh to 11wl includes two switching elements connected in parallel, but may include three or more switching elements connected in parallel, in which case a coil unit is provided corresponding to each switching element. In the present embodiment, the coil portion 23a has a circular winding 32a, but may have a winding of another shape, such as a rectangular shape. Furthermore, the coil portion 23 a in this embodiment may be fixed to the element package PKG so as to be adjacent to the first current path 29 and the second current path 30 . In the present embodiment, the switching element 11ula has an element package PKG mounted upright on the circuit board 10, but may be a surface-mount switching element in which the element package PKG is mounted along the circuit board 10. In this case as well, the coil portion 23a is fixed adjacent to the first current terminal T1 and the second current terminal T2 extending from the element package PKG. In addition, the switching element 11ula in this embodiment may be a three-terminal package having a drain terminal, a source terminal, and a gate terminal. For example, the switching element 11ula may have a configuration in which the gate terminal, the drain terminal, and the source terminal are arranged in this order at an end of the element package PKG. In this case, too, the coil portion 23a is fixed close to the drain terminal and the source terminal extending from the element package PKG. Further, the switching circuit unit 11ul and the driver circuit 13ul in this embodiment may have other circuit configurations. Figures 5 and 6 are diagrams showing the configurations of the switching circuit unit 11ul and the driver circuit 13ul according to first and second modified examples. 5, the switching circuit unit 11ul is configured with one switching element 11ula and a free wheel diode Dula connected in parallel thereto. The driver circuit 13ul includes a coil unit 23a, a command conversion circuit 40, a feedback conversion circuit 41, and an adder circuit 42. The command conversion circuit 40 amplifies the external command voltage Vref input from the control device 15 to a drive signal Vg at a predetermined amplification factor and outputs the drive signal Vg to the adder circuit 42. The feedback conversion circuit 41 amplifies the voltage Vf generated across the coil portion 23a at a predetermined amplification factor to convert it into a converted feedback voltage Vft, and outputs the converted feedback voltage Vft to the adder circuit 42. The adder circuit 42 adds the drive signal Vg and the converted feedback voltage Vft to generate a sum voltage Vad, and applies the sum voltage Vad to the gate of the switching element 11ula. With this first modification, it is possible to reduce the surge voltage and the switching loss while maintaining the switching speed of the switching element 11ula. In the second modified example shown in Fig. 6, the connection position of the coil portion 23a in the driver circuit 13ul is different from that of the above-mentioned embodiment. That is, the coil portion 23a is connected between the source of the switching element 11ula and the reference potential terminal 25b of the drive circuit 25. In detail, one end of the coil portion 23a is connected to the driver source terminal T3 via the wiring pattern P5 (Fig. 4(a)) on the circuit board 10, and the other end of the coil portion 23a is connected to the reference potential terminal 25b via the wiring pattern P6 (Fig. 4(a)) on the circuit board 10. Even with such a second modified example, it is possible to reduce the surge voltage and the switching loss while maintaining the switching speed of the switching element 11ula. In the above embodiment, the coil portion 23a is fixed to both the first current terminal T1 and the second current terminal T2. As another modification, the coil portion 23a may be fixed to the circuit board 10. For example, a hole may be formed on the circuit board 10, and the tip of the coil portion 23a may be inserted into the hole, thereby fixing the coil portion 23a to the circuit board 10. As another modification, the coil portion 23a may be fixed to the element package PKG, or may be fixed across the element package PKG and at least one of the first current terminal T1 and the second current terminal T2. As yet another modification, the coil portion 23a may be fixed to at least one of the first current terminal T1 and the second current terminal T2. In the above embodiment, the coil portion 23a is disposed between the first current path 29 on the first current terminal T1 and the second current path 30 on the second current terminal T2. As a modified embodiment, when viewed from a direction perpendicular to the XY plane, at least a part of the coil portion 23a may be disposed so as to overlap the first wiring portion 21a or the second wiring portion 22a in the element package PKG. Alternatively, as another modified embodiment, when viewed from a direction perpendicular to the XY plane, at least a part of the coil portion 23a may be disposed so as to overlap the first current terminal T1 or the second current terminal T2. In one aspect of the above embodiment, the coil section may be fixed to the element package or at least one of the first current terminal and the second current terminal. In this case, the current path through which the main current flows and the coil section can be stably brought close to each other, and the inductance component through which the main current flows and the coil section are efficiently and stably magnetically coupled. Specifically, since the coil section is integrated with the terminal or the package, it is not necessary to adjust the positional relationship between the coil section and the first and second current paths, as compared with the case in which the coil section is not fixed to the terminal or the package, and the coil section can be easily provided at a position where it is magnetically coupled to the first and second current paths. As a result, it is possible to further reduce switching loss. In the above aspect, the coil portion may be a conductor wound in a ring shape and may have an iron core inserted inside the conductor. In this case, the inductance component through which the main current flows and the coil portion are magnetically coupled even stronger. By increasing the magnetic coupling, it is possible to increase the detection voltage generated in the coil portion due to the time change of the main current. As a result, it is possible to further reduce switching loss. In the above aspect, the coil unit may be connected in series between the drive circuit and the control terminal to form an adjustment circuit, whereby it is possible to reduce switching loss while maintaining the switching speed. In the above aspect, the coil portion may be connected between the second current terminal and a reference potential terminal of the drive circuit to form an adjustment circuit, whereby it is possible to reduce switching loss while maintaining the switching speed. The power conversion device of the embodiment is a power conversion device comprising: [1] "a switching element accommodated in an element package, the switching element having a control terminal, a first current terminal into which a main current flows, and a second current terminal from which the main current flows out; a first wiring portion connected to the first current terminal of the switching element and having an inductance component; a second wiring portion connected to the second current terminal of the switching element and having an inductance component; a coil portion which is a conductor arranged to be magnetically coupled to both a first current path from the first wiring portion to the first current terminal and a second current path from the second current terminal to the second wiring portion; a drive circuit which generates a drive signal and supplies the drive signal to the control terminal of the switching element; and an adjustment circuit which adjusts the drive signal based on the voltage generated across the coil portion." The power conversion device of the embodiment has the following features: [2] "The coil unit is fixed to the element package or to at least one of the first current terminal and the second current terminal; The power conversion device may be the power conversion device described in [1] above. The power conversion device of the embodiment has a configuration in which: [3] "the coil portion is a conductor wound in a ring shape and has an iron core inserted inside the conductor; The power conversion device may be the power conversion device according to the above [1] or [2]. The power conversion device of the embodiment has the following features: [4] "The coil unit is connected in series between the drive circuit and the control terminal to form the adjustment circuit; The power conversion device may be the power conversion device according to any one of the above items [1] to [3]. The power conversion device of the embodiment is, [5] "the coil unit is connected between the second current terminal and a reference potential terminal of the drive circuit to form the adjustment circuit, The power conversion device may be the power conversion device according to any one of the above items [1] to [3]. Reference Signs List 1... Power conversion device, 11uh, 11ul, 11vh, 11vl, 11wh, 11wl... Switching circuit section, 11ula, 11ulb... Switching elements, 13uh, 13ul, 13vh, 13vl, 13wh, 13wl... Driver circuit (circuit section), 21a, 21b... First wiring section, 22a, 22b... Second wiring section, 23a, 23b... Coil section, 25... Drive circuit, 25b... Reference potential terminal, 27...adjustment circuit, 29...first current path, 30...second current path, 31a...iron core, 32a...winding (conductor), Is...main current (source current), Ld, Ls...inductance components (stray inductance), PKG...element package, T1...first current terminal (drain terminal), T2...second current terminal (power source terminal), Vf...voltage, Vg...gate voltage (drive signal).

Claims

1. A power conversion device comprising: a switching element accommodated in an element package, the switching element having a control terminal, a first current terminal into which a main current flows, and a second current terminal from which the main current flows out; a first wiring section connected to the first current terminal of the switching element and having an inductance component; a second wiring section connected to the second current terminal of the switching element and having an inductance component; a coil section which is a conductor arranged to be magnetically coupled to both a first current path from the first wiring section to the first current terminal and a second current path from the second current terminal to the second wiring section; a drive circuit which generates a drive signal and supplies the drive signal to the control terminal of the switching element; and an adjustment circuit which adjusts the drive signal based on the voltage generated across both ends of the coil section.

2. The power conversion device according to claim 1, wherein the coil section is fixed to at least one of the element package and the first current terminal and the second current terminal.

3. A power conversion device as described in claim 1 or 2, wherein the coil portion is a conductor wound in a ring shape and has an iron core inserted inside the conductor.

4. A power conversion device according to any one of claims 1 to 3, wherein the coil section is connected in series between the drive circuit and the control terminal to form the adjustment circuit.

5. A power conversion device according to any one of claims 1 to 3, wherein the coil section is connected between the second current terminal and a reference potential terminal of the drive circuit to form the adjustment circuit.

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