Power conversion device

Abstract

The present invention provides a power conversion device. The power conversion device (10) includes: two lower arm switching elements (11ya, 11yb) connected in parallel to each other, and a lower arm drive circuit (12y) that drives the two lower arm switching elements (11ya, 11yb). The two lower arm switching elements (11ya, 11yb) include gate terminals (21a, 21b) and detection terminals (24a, 24b) for detecting back electromotive force (Vb1, Vb2). Here, the power conversion device (10) includes a common connection line (43) that connects the two detection terminals (24a, 24b) to each other and connects the two detection terminals (24a, 24b) to an adding circuit (60) of the lower arm drive circuit (12y), and transmits a synthetic electromotive force (Vss).

Description

Technical Field

[0001] The present invention relates to a power conversion device. Background Art

[0002] For example, Patent Document 1 describes a drive circuit for driving an IGBT, which serves as a switching element. To simultaneously reduce switching losses and surge voltage or surge current, the drive circuit described in Patent Document 1 performs active gate control by feeding back an induced voltage, which is a back electromotive force generated by the inductance of the emitter wiring.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-48843

[0004] Here, in a power conversion device having switching elements, for example, in order to flow a relatively large current, the switching elements may be connected in parallel, and a drive circuit may be used to operate the two switching elements in synchronization.

[0005] In the above structure, the inventors of the present application found that even when the same voltage is used to control two switching elements, the operation of the switching elements will deviate due to element deviation. Due to this deviation, an obstacle will occur in the feedback based on the back electromotive force, and there may be a situation where it is impossible to simultaneously achieve the reduction of power loss and the suppression of surges. Summary of the Invention

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power conversion device capable of simultaneously reducing power loss and suppressing surges even when deviation occurs in the operation of two switching elements connected in parallel.

[0007] The power conversion device for achieving the above-mentioned purpose comprises: a first switching element, which flows a first applied current when it is in an on state; a second switching element, which is connected in parallel with the first switching element and flows a second applied current when it is in an on state; and a drive circuit, which drives the two switching elements, the first switching element comprising: a first control terminal; a first parasitic inductance, which flows the first applied current; and a first detection terminal, which is used to detect a first back electromotive force generated by a first inductance component including the first parasitic inductance, the second switching element comprising: a second control terminal; a second parasitic inductance, which flows the second applied current; and a second detection terminal, which is used to detect a first back electromotive force generated by a first inductance component including the first parasitic inductance. The second back electromotive force generated by the second inductance component of the second parasitic inductance, the above-mentioned driving circuit comprises: an external input terminal for inputting an external command voltage; an adding circuit for outputting a summed voltage; and an adding output terminal for outputting the above-mentioned summed voltage, the above-mentioned power conversion device comprises: a control line for connecting the above-mentioned summed output terminal with the above-mentioned two control terminals; and a common connecting line for connecting the above-mentioned two detection terminals to each other and connecting the above-mentioned two detection terminals to the above-mentioned adding circuit, and transmitting the synthetic electromotive force of the above-mentioned two back electromotive forces, the above-mentioned adding circuit is input with the above-mentioned synthetic electromotive force and the above-mentioned external command voltage, and outputs the above-mentioned summed voltage by adding the above-mentioned synthetic electromotive force and the above-mentioned external command voltage.

[0008] According to the above structure, the two switching elements connected in parallel operate based on the added voltage. As a result, the two switching elements operate synchronously. Therefore, a current equal to the sum of the two applied currents can flow, allowing a larger current to flow than when using only one switching element.

[0009] Here, according to this configuration, the two detection terminals are connected to each other via a common connection line and are also connected to the adding circuit. This allows the combined electromotive force of the two back electromotive forces to be input as the voltage fed back to the adding circuit. Therefore, even if there is a deviation in the operation of the two switching elements, feedback based on the two back electromotive forces can be applied to the two switching elements, achieving both reduced power loss and surge suppression.

[0010] Regarding the above-mentioned power conversion device, the above-mentioned drive circuit may also have a feedback input terminal for inputting the above-mentioned synthetic electromotive force, and the above-mentioned common connecting line may also have: a first local line, which connects the above-mentioned two detection terminals to each other and connects the above-mentioned two detection terminals to the above-mentioned feedback input terminal; and a second local line, which is arranged in the above-mentioned drive circuit and connects the above-mentioned feedback input terminal to the above-mentioned adding circuit.

[0011] According to the above configuration, the two back electromotive forces are combined via the first local line and input to the feedback input terminal. Furthermore, the combined electromotive force is transmitted via the second local line and input to the adder circuit. This achieves the aforementioned effect. Furthermore, according to this configuration, the drive circuit does not need to have two feedback input terminals corresponding to the two back electromotive forces, thus simplifying the drive circuit structure.

[0012] The power conversion device may further include a voltage amplifier circuit provided on the second local line and configured to amplify the resultant electromotive force.

[0013] According to the above configuration, the combined electromotive force is amplified by the voltage amplifier circuit and then input to the adding circuit. Thus, even when the voltage generated by the two inductance components is small, a combined electromotive force of a desired magnitude can be input to the adding circuit.

[0014] Regarding the above-mentioned power conversion device, the above-mentioned first switching element and the above-mentioned second switching element may also include: a first upper arm switching element and a second upper arm switching element connected in parallel with each other; and a first lower arm switching element and a second lower arm switching element connected in parallel with each other, and the parallel connection body of the above-mentioned first upper arm switching element and the above-mentioned second upper arm switching element and the parallel connection body of the above-mentioned first lower arm switching element and the above-mentioned second lower arm switching element may also be connected in series. The above-mentioned power conversion device may also include: a positive bus bar connecting the above-mentioned two upper arm switching elements; a negative bus bar connecting the above-mentioned two lower arm switching elements and connected to a reference potential; and an upper arm driving circuit driving the above-mentioned two upper arm switching elements as the above-mentioned driving circuit, and a negative bus bar driving the above-mentioned two lower arm switching elements. The lower arm driving circuit of the arm switching element may also apply the first back electromotive force of a negative voltage to the first detection terminal of the first lower arm switching element and apply the second back electromotive force of a negative voltage to the second detection terminal of the second lower arm switching element when the first lower arm switching element and the second lower arm switching element are disconnected. The common connecting line may also connect the two detection terminals of the two lower arm switching elements to each other and connect the two detection terminals to the adding circuit of the lower arm driving circuit. The power conversion device may also have an inverting circuit arranged on the common connecting line and inverting the synthetic electromotive force, and may also input the synthetic electromotive force inverted by the inverting circuit into the adding circuit.

[0015] According to the above structure, the negative bus is connected to the reference potential, and under the conditions of detecting the back electromotive force of the positive voltage when the two lower arm switching elements are turned on and detecting the back electromotive force of the negative voltage when the two lower arm switching elements are turned off, feedback using the back electromotive force can be performed on the two lower arm switching elements.

[0016] To achieve the above-mentioned purpose, a power conversion device comprises: a first switching element, which, when in an on state, allows a first applied current to flow; a second switching element, which is connected in parallel with the first switching element and, when in an on state, allows a second applied current to flow; and a drive circuit, which drives the two switching elements, the first switching element comprising: a first control terminal; and a first output terminal, the second switching element comprising: a second control terminal; and a second output terminal, the drive circuit comprising: an external input terminal for inputting an external command voltage; an adding circuit for outputting a summed voltage; and an adding output terminal for outputting the summed voltage, the power conversion device comprising: a control line connecting the summed output terminal to the two control terminals; and a detection line having an inductance, connecting the two output terminals to each other and connecting the output terminal to the adding circuit in a manner that a back electromotive force generated by the inductance is input to the adding circuit, the adding circuit receiving the back electromotive force and the external command voltage and outputting the summed voltage by adding the back electromotive force and the external command voltage.

[0017] According to the above configuration, even when there is a deviation in the operation of the two switching elements, feedback can be applied to the two switching elements, thereby achieving both reduction in power loss and suppression of surges. In addition, there is no need to provide detection terminals on the switching elements.

[0018] In the above-mentioned power conversion device, the detection line may be a wiring pattern provided on a substrate.

[0019] According to the present invention, even when a deviation occurs in the operation of two switching elements connected in parallel, it is possible to simultaneously achieve reduction in power loss and suppression of surges. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a circuit diagram schematically showing the electrical configuration of the power conversion device according to the first embodiment.

[0021] Figure 2 This is a block circuit diagram showing the electrical configuration of a lower-arm drive circuit and two lower-arm switching elements.

[0022] Figure 3 This is the circuit diagram of the lower arm drive circuit.

[0023] Figure 4 (a) is a waveform of the external command voltage when the device is turned on, (b) is a graph schematically showing changes in the synthetic electromotive force, (c) is a graph schematically showing changes in the first drain current, and (d) is a graph schematically showing changes in the second drain current.

[0024] Figure 5This is a block circuit diagram showing the electrical configuration of a lower arm drive circuit and two lower arm switching elements of the power conversion device according to the second embodiment.

[0025] Figure 6 This is a block circuit diagram showing another example of common connection lines. DETAILED DESCRIPTION

[0026] (First embodiment)

[0027] Hereinafter, an embodiment of a power conversion device will be described.

[0028] The power conversion device 10 of the present embodiment is mounted on, for example, a vehicle 200 , and is used to drive an electric motor 201 provided in the vehicle 200 .

[0029] Specifically, the electric motor 201 of this embodiment is a driving motor for rotating the wheels of the vehicle 200. The electric motor 201 of this embodiment includes three-phase coils 202u, 202v, and 202w. The three-phase coils 202u, 202v, and 202w are, for example, Y-connected. Electricity is supplied to the three-phase coils 202u, 202v, and 202w in a predetermined pattern, thereby rotating the electric motor 201. The connection method of the three-phase coils 202u, 202v, and 202w is not limited to a Y connection but can be any connection method, such as a delta connection.

[0030] like Figure 1 As shown, vehicle 200 includes a power storage device 203. The power conversion device 10 of this embodiment is an inverter device that converts the DC power of the power storage device 203 into AC power capable of driving the electric motor 201. In other words, the power conversion device 10 can also be said to be a drive device that uses the power storage device 203 to drive the electric motor 201.

[0031] The power conversion device 10 includes a switching element 11. The switching element 11 is, for example, a power switching element, such as a power MOSFET. The switching element 11 includes a freewheeling diode connected in antiparallel. The freewheeling diode is, for example, a parasitic diode within the switching element 11. However, the present invention is not limited to this, and the freewheeling diode may be provided separately from the switching element 11.

[0032] The power conversion device 10 of this embodiment has a plurality of switching elements 11. Specifically, the power conversion device 10 has, as switching elements 11, u-phase upper arm switching elements 11uua and 11uub corresponding to the u-phase coil 202u, and u-phase lower arm switching elements 11uda and 11udb. The two u-phase upper arm switching elements 11uua and 11uub are connected in parallel with each other. The two u-phase lower arm switching elements 11uda and 11udb are connected in parallel with each other. The parallel connection of the two u-phase upper arm switching elements 11uua and 11uub and the parallel connection of the two u-phase lower arm switching elements 11uda and 11udb are connected in series via a u-connecting wiring LNu, and the u-connecting wiring LNu is connected to the u-phase coil 202u.

[0033] Similarly, the power conversion device 10 includes, as switching elements 11, v-phase upper arm switching elements 11vua and 11vub, and v-phase lower arm switching elements 11vda and 11vdb, corresponding to the v-phase coil 202v. The two v-phase upper arm switching elements 11vua and 11vub are connected in parallel with each other. The two v-phase lower arm switching elements 11vda and 11vdb are connected in parallel with each other. The parallel connection of the two v-phase upper arm switching elements 11vua and 11vub and the parallel connection of the two v-phase lower arm switching elements 11vda and 11vdb are connected in series via a v-connecting wiring LNv, which is connected to the v-phase coil 202v.

[0034] The power conversion device 10 includes, as the switching element 11, w-phase upper arm switching elements 11wua and 11wub, and w-phase lower arm switching elements 11wda and 11wdb, corresponding to the w-phase coil 202w. The two w-phase upper arm switching elements 11wua and 11wub are connected in parallel with each other. The two w-phase lower arm switching elements 11wda and 11wdb are connected in parallel with each other. The parallel connection of the two w-phase upper arm switching elements 11wua and 11wub and the parallel connection of the two w-phase lower arm switching elements 11wda and 11wdb are connected in series via a w-connecting wiring LNw, which is connected to the w-phase coil 202w.

[0035] For ease of explanation, in the following description, the u-phase upper arm switching elements 11uua, 11uub, the v-phase upper arm switching elements 11vua, 11vub, and the w-phase upper arm switching elements 11wua, 11wub are also referred to simply as upper arm switching elements 11xa, 11xb. Furthermore, the u-phase lower arm switching elements 11uda, 11udb, the v-phase lower arm switching elements 11vda, 11vdb, and the w-phase lower arm switching elements 11wda, 11wdb are also referred to simply as lower arm switching elements 11ya, 11yb.

[0036] The power conversion device 10 includes a positive busbar LN1 to which two upper arm switching elements 11xa and 11xb are connected, and a negative busbar LN2 to which two lower arm switching elements 11ya and 11yb are connected. Positive busbar LN1 is connected to the positive terminal (+ terminal) on the high-voltage side of the power storage device 203, and negative busbar LN2 is connected to the negative terminal (- terminal) on the low-voltage side of the power storage device 203. In other words, a series connection of the upper arm switching elements 11xa and 11xb and the lower arm switching elements 11ya and 11yb is connected to the positive busbar LN1 and the negative busbar LN2, supplying DC power from the power storage device 203. In this embodiment, the negative busbar LN2 is connected to a reference potential V0. Therefore, the lower arm switching elements 11ya and 11yb are also connected to the reference potential V0.

[0037] like Figure 1 as well as Figure 2 As shown, the power conversion device 10 includes a drive circuit 12 that drives a switching element 11 .

[0038] The drive circuit 12 of this embodiment is a so-called gate drive circuit. The power conversion device 10 of this embodiment is provided with multiple drive circuits 12 corresponding to the multiple switching elements 11. Specifically, the power conversion device 10 includes a u-phase upper arm drive circuit 12uu that drives the u-phase upper arm switching elements 11uua and 11uub, and a u-phase lower arm drive circuit 12ud that drives the u-phase lower arm switching elements 11uda and 11udb.

[0039] The u-phase upper arm drive circuit 12uu is connected to the gates of the two u-phase upper arm switching elements 11uua and 11uub, and controls the gate voltage to turn the two u-phase upper arm switching elements 11uua and 11uub on and off. In this embodiment, the u-phase upper arm drive circuit 12uu outputs the same gate voltage to the two u-phase upper arm switching elements 11uua and 11uub. As a result, the two u-phase upper arm switching elements 11uua and 11uub are synchronized.

[0040] Similarly, the u-phase lower arm drive circuit 12ud is connected to the gates of the two u-phase lower arm switching elements 11uda and 11udb, and outputs the same gate voltage to the two u-phase lower arm switching elements 11uda and 11udb, thereby performing switching operations in a synchronized state.

[0041] The power conversion device 10 includes a v-phase upper arm drive circuit 12vu that drives the v-phase upper arm switching elements 11vua and 11vub, and a v-phase lower arm drive circuit 12vd that drives the v-phase lower arm switching elements 11vda and 11vdb. The power conversion device 10 includes a w-phase upper arm drive circuit 12wu that drives the w-phase upper arm switching elements 11wua and 11wub, and a w-phase lower arm drive circuit 12wd that drives the w-phase lower arm switching elements 11wda and 11wdb. This structure is identical to that of the u-phase upper arm drive circuit 12uu and the u-phase lower arm drive circuit 12ud, and therefore a detailed description thereof will be omitted.

[0042] For convenience of explanation, in the following description, the upper arm drive circuits 12uu, 12vu, and 12wu are simply referred to as upper arm drive circuits 12x, and the lower arm drive circuits 12ud, 12vd, and 12wd are simply referred to as lower arm drive circuits 12y.

[0043] like Figure 1 As shown, vehicle 200 includes a conversion control device 13 that controls power conversion device 10. In this embodiment, conversion control device 13 is an inverter control device. Based on an external command (e.g., a required rotational speed), conversion control device 13 determines a target current flowing to electric motor 201 and derives an external command voltage Vp for flowing this target current. Conversion control device 13 then outputs external command voltage Vp to drive circuit 12.

[0044] In this embodiment, the switching control device 13 derives an external command voltage Vp for each of the drive circuits 12uu to 12wd and outputs the external command voltage Vp to each of the drive circuits 12uu to 12wd, thereby controlling the upper arm switching elements 11xa and 11xb and the lower arm switching elements 11ya and 11yb of each phase.

[0045] Next, use Figure 2 as well as Figure 3 The switching element 11 and the drive circuit 12 will be described in detail. Since the upper arm and the lower arm have basically the same structure, for ease of description, the lower arm switching elements 11ya and 11yb and the lower arm drive circuit 12y will be described in detail below.

[0046] like Figure 2 As shown, the first lower arm switching element 11ya is a switching element through which a first drain current Id1 as a first applied current flows when the first lower arm switching element 11ya is in an on state. The first drain current Id1 is a current flowing between the source and the drain of the first lower arm switching element 11ya.

[0047] The first lower arm switching element 11ya includes a first gate terminal 21a as a first control terminal to which a gate voltage is input, a first drain terminal 22a through which a first drain current Id1 flows when in an on state, and a first source terminal 23a. The first source terminal 23a is also called an apply terminal through which an apply current flows.

[0048] In this embodiment, first drain terminal 22a of first lower arm switching element 11ya is connected to the source terminals of upper arm switching elements 11xa and 11xb, and first source terminal 23a is connected to negative bus LN2. In this embodiment, negative bus LN2 is connected to reference potential V0, so reference potential V0 is applied to first source terminal 23a.

[0049] In this embodiment, the first lower arm switching element 11ya has a first parasitic inductance Ls1, through which the first drain current Id1 flows. The first parasitic inductance Ls1 is formed, for example, by the wiring pattern, wires, and first source terminal 23a within the switching element 11. The first parasitic inductance Ls1 is equivalently provided in the current path through which the first drain current Id1 flows. Specifically, the first parasitic inductance Ls1 is provided between the main body of the first lower arm switching element 11ya and the first source terminal 23a, and is connected in series with the main body of the first lower arm switching element 11ya.

[0050] Here, the first lower arm switching element 11 ya includes a first detection terminal 24 a for detecting a first counter electromotive force Vb1 generated by a first inductance component L1 including a first parasitic inductance Ls1 .

[0051] The first inductance component L1 is a component that generates the first back electromotive force Vb1 due to changes in the first drain current Id1. The first inductance component L1 may or may not include other inductances, such as parasitic inductance contained in wiring (patterns) outside the first lower arm switching element 11ya. Furthermore, changes in the first drain current Id1 include both when the first drain current Id1 begins to flow and when the first drain current Id1 stops flowing.

[0052] The first detection terminal 24a is a terminal through which the first drain current Id1 is less likely to flow. Although details will be described later, the first detection terminal 24a is connected to the input terminal of the feedback operational amplifier 101 via the feedback input terminal 33 provided in the lower arm drive circuit 12y. Therefore, the impedance of the first detection terminal 24a, as viewed from within the first lower arm switching element 11ya, is higher than that of the first source terminal 23a, making it less likely for the first drain current Id1 to flow into the first detection terminal 24a. Therefore, the first detection terminal 24a can be considered to be equivalently connected between the main body of the first lower arm switching element 11ya and the first parasitic inductance Ls1.

[0053] With the above configuration, when the first drain current Id1 changes, the first inductance component L1 including the first parasitic inductance Ls1 generates a first back electromotive force Vb1, which is applied to the first detection terminal 24a. Thus, the first back electromotive force Vb1 can be detected by detecting the voltage applied to the first detection terminal 24a.

[0054] Furthermore, the first back electromotive force Vb1 generated by the first inductance component L1 is a positive voltage when the first drain current Id1 increases, and a negative voltage when the first drain current Id1 decreases. Specifically, when the first lower arm switching element 11ya is on, a positive first back electromotive force Vb1 is applied to the first detection terminal 24a. On the other hand, when the first lower arm switching element 11ya is off, a negative first back electromotive force Vb1 is applied to the first detection terminal 24a.

[0055] The specific structure of the first detection terminal 24a is arbitrary. For example, if the first lower arm switching element 11ya has multiple first source terminals 23a, it may be a portion of the multiple first source terminals 23a. Furthermore, for example, if the first lower arm switching element 11ya has a gate drive terminal separate from the first source terminal 23a, the gate drive terminal may be used as the first detection terminal 24a. The gate drive terminal, also known as a Kelvin terminal or a Kelvin source terminal, is a source terminal through which the first drain current Id1 does not flow. The gate drive terminal may, for example, be a terminal having a smaller first parasitic inductance Ls1 than the first source terminal 23a.

[0056] The second lower arm switching element 11yb is similar to the first lower arm switching element 11ya. Specifically, when in the on state, the second lower arm switching element 11yb allows a second drain current Id2 to flow as a second applied current. The second drain current Id2 flows between the source and drain of the second lower arm switching element 11yb.

[0057] The second lower-arm switching element 11yb includes a second gate terminal 21b serving as a second control terminal, a second drain terminal 22b through which a second drain current Id2 flows when in the on state, and a second source terminal 23b. Furthermore, the second lower-arm switching element 11yb includes a second parasitic inductance Ls2 and a second detection terminal 24b for detecting a second back electromotive force Vb2 generated by a second inductance component L2 including the second parasitic inductance Ls2. When the second lower-arm switching element 11yb is on, a positive second back electromotive force Vb2 is applied to the second detection terminal 24b. When the second lower-arm switching element 11yb is off, a negative second back electromotive force Vb2 is applied to the second detection terminal 24b. Since this structure is identical to the corresponding structure of the first lower-arm switching element 11ya, a detailed description will be omitted.

[0058] Next, the connection between the lower arm drive circuit 12y and the two lower arm switching elements 11ya and 11yb and the lower arm drive circuit 12y will be described.

[0059] like Figure 2 as well as Figure 3 As shown, the lower arm drive circuit 12 y includes an external input terminal 31 , an addition output terminal 32 , a feedback input terminal 33 , a filter circuit 50 , an addition circuit 60 , a current amplifier circuit 70 , a voltage divider circuit 90 , and a voltage amplifier circuit 100 .

[0060] The power conversion device 10 includes: an external input line 41 connecting the external input terminal 31 and the adding circuit 60; a control line 42 connecting the adding output terminal 32 and the two gate terminals 21a and 21b; and a common connection line 43 connecting the two detection terminals 24a and 24b to each other and connecting the two detection terminals 24a and 24b to the adding circuit 60.

[0061] External input terminal 31 is electrically connected to switching control device 13 . External command voltage Vp from switching control device 13 is input to external input terminal 31 . External command voltage Vp input to external input terminal 31 is transmitted through external input line 41 and input to adding circuit 60 .

[0062] The addition output terminal 32 is a terminal for outputting a gate voltage (in other words, a gate current) from the lower arm drive circuit 12y. The added voltage Vad, which is the gate voltage output from the addition output terminal 32, is input to the two gate terminals 21a and 21b via the control line 42.

[0063] The feedback input terminal 33 in this embodiment is a terminal for inputting the combined electromotive force Vss of the two back electromotive forces Vb1 and Vb2. Specifically, the common connection line 43 includes a first local line 43a that connects the two detection terminals 24a and 24b to each other and connects the two detection terminals 24a and 24b to the feedback input terminal 33. In this embodiment, the first local line 43a is, for example, a wiring pattern formed on the circuit board on which the two lower-arm switching elements 11ya and 11yb and the lower-arm drive circuit 12y are mounted. However, this is not limiting, and the specific structure of the first local line 43a is arbitrary, and may also be a conductive wire, etc.

[0064] Here, the two detection terminals 24a, 24b are connected to each other through the first local line 43a, thereby Figure 2 As shown by the two-dot chain line, the first parasitic inductance Ls1 and the second parasitic inductance Ls2 can be equivalently considered to be connected in parallel. As a result, the combined electromotive force Vss of the first back electromotive force Vb1 and the second back electromotive force Vb2 is input to the feedback input terminal 33. Specifically, the combined electromotive force Vss is the average value of the two back electromotive forces Vb1 and Vb2.

[0065] When the first detection terminal 24a and the second detection terminal 24b are short-circuited, the first back electromotive force Vb1 and the second back electromotive force Vb2 become the same voltage, and the combined electromotive force Vss becomes the same voltage as the first back electromotive force Vb1 and the second back electromotive force Vb2 (Vss=Vb1=Vb2).

[0066] The filter circuit 50 is provided on the external input line 41. The filter circuit 50 is a circuit that reduces noise included in the external command voltage Vp input from the external input terminal 31. The filter circuit 50 is, for example, a low-pass filter circuit.

[0067] like Figure 3 As shown, the filter circuit 50 includes, for example, a filter operational amplifier 51 , a first filter resistor 52 , a second filter resistor 53 , and a filter capacitor 54 .

[0068] The external input terminal 31 is connected to the + terminal (non-inverting input terminal) of the filter operational amplifier 51 through the external input line 41 , and the output terminal of the filter operational amplifier 51 is connected to the adding circuit 60 .

[0069] The negative terminal (inverting input terminal) and the output terminal of the filter operational amplifier 51 are connected via a first filter resistor 52. A filter capacitor 54 is connected in parallel with the first filter resistor 52. A second filter resistor 53 is connected in series with the first filter resistor 52 and the filter capacitor 54 and is connected to a reference potential V0.

[0070] According to the above configuration, the external command voltage Vp is output from the filter circuit 50, specifically, from the output terminal of the filter operational amplifier 51, and is input to the adder circuit 60. This external command voltage Vp is amplified by the RC circuit formed by the first filter resistor 52 and the filter capacitor 54, thereby reducing (in other words, removing) noise above the cutoff frequency and amplifying it at an amplification factor corresponding to the ratio of the resistance values ​​of the two filter resistors 52 and 53. The specific configuration of the filter circuit 50 is arbitrary.

[0071] like Figure 3 As shown, the adding circuit 60 is configured to input the external command voltage Vp and the combined electromotive force Vss output from the filter circuit 50 .

[0072] Specifically, the common connection line 43 includes a second local line 43b that connects the feedback input terminal 33 to the adding circuit 60. The second local line 43b is provided within the lower arm drive circuit 12y and transmits the combined electromotive force Vss. The combined electromotive force Vss input to the feedback input terminal 33 is input to the adding circuit 60 via the second local line 43b.

[0073] The adding circuit 60 adds the external command voltage Vp and the combined electromotive force Vss, and outputs the added voltage Vad to both gate terminals 21 a and 21 b .

[0074] Specifically, the adding circuit 60 of the present embodiment includes, for example, an adding operational amplifier 61 , a first adding resistor 62 , a second adding resistor 63 , and an adding capacitor 64 .

[0075] The external input line 41 in this embodiment includes a portion connecting the output terminal of the filter operational amplifier 51 to the + terminal (non-inverting input terminal) of the adding operational amplifier 61. Furthermore, the second local line 43b in this embodiment connects the feedback input terminal 33 to the external input line 41. In other words, the adding circuit 60 has a connection point between the external input line 41 and the second local line 43b. Consequently, a voltage resulting from the sum of the external command voltage Vp and the resultant electromotive force Vss is input to the + terminal of the adding operational amplifier 61.

[0076] The negative terminal (inverting input terminal) and the output terminal of the adding operational amplifier 61 are connected via a first adding resistor 62, and an adding capacitor 64 is connected in parallel with the first adding resistor 62. A second adding resistor 63 is connected in series with the first adding resistor 62 and the adding capacitor 64 and is connected to a reference potential V0.

[0077] With the above configuration, a summed voltage Vad, which is the sum of the external command voltage Vp and the resultant electromotive force Vss, is output from the output terminal of the adding operational amplifier 61. This summed voltage Vad is amplified by an RC circuit formed by the first adding resistor 62 and the adding capacitor 64, whereby noise above the cutoff frequency is reduced (in other words, removed) and amplified at an amplification factor corresponding to the ratio of the resistance values ​​of the two adding resistors 62 and 63. The specific configuration of the adding circuit 60 is arbitrary.

[0078] The current amplifier circuit 70 is a circuit for maintaining the waveform of the added voltage Vad and supplying a current required to drive the switching element 11 .

[0079] like Figure 3 As shown, the current amplifier circuit 70 of this embodiment includes, for example, a first amplifying switch element 71 and a second amplifying switch element 72. The first amplifying switch element 71 and the second amplifying switch element 72 are, for example, n-type MOSFETs.

[0080] The drain of the first amplifying switching element 71 is connected to a first supply source E1 that applies a first supply voltage V1. The source of the second amplifying switching element 72 is connected to a second supply source E2 that applies a second supply voltage V2. The first supply voltage V1 is, for example, a positive voltage, and the second supply voltage V2 is, for example, a negative voltage. The source of the first amplifying switching element 71 and the drain of the second amplifying switching element 72 are connected via a connecting line 75. Furthermore, two diodes 73 and 74 are provided on the connecting line 75, connected in opposite directions to each other.

[0081] The gates of the two amplifying switching elements 71 and 72 are connected to the adding circuit 60 (specifically, the output terminal of the adding operational amplifier 61). A first Zener diode 76 is provided between the gate of the first amplifying switching element 71 and the adding circuit 60. The anode of the first Zener diode 76 is connected to the adding circuit 60, and the cathode of the first Zener diode 76 is connected to the gate of the first amplifying switching element 71.

[0082] A second Zener diode 77 is provided between the gate of the second amplifying switch element 72 and the adding circuit 60. The cathode of the second Zener diode 77 is connected to the adding circuit 60, and the anode of the second Zener diode 77 is connected to the gate of the second amplifying switch element 72. The added voltage Vad output by the adding circuit 60 is input to the gate of the second amplifying switch element 72 via the second Zener diode 77.

[0083] According to the above configuration, the sum voltage Vad is output from the connection line 75 connecting the two diodes 73 and 74 , and the gate current required to drive the switching element 11 is supplied from the two supply sources E1 and E2 .

[0084] The output of the current amplifier circuit 70 (specifically, the connection line 75) is connected to the summing output terminal 32. Consequently, the summed voltage Vad is output from the summing output terminal 32 and input to the two gate terminals 21a and 21b via the control line 42. That is, in this embodiment, the summed voltage Vad serves as the gate voltage. The specific configuration of the current amplifier circuit 70 is arbitrary.

[0085] like Figure 3 As shown, the lower arm drive circuit 12y includes a gate resistor 80 provided on a line connecting the current amplifier circuit 70 and the addition output terminal 32. The gate resistor 80 adjusts the gate current.

[0086] like Figure 2 as well as Figure 3 As shown, the power conversion device 10 of this embodiment includes a voltage divider circuit 90 and a voltage amplifier circuit 100 provided on the common connection line 43. In this embodiment, the voltage divider circuit 90 and the voltage amplifier circuit 100 are provided on the second local line 43b.

[0087] like Figure 3 As shown, voltage divider circuit 90 divides the combined electromotive force Vss. Specifically, voltage divider circuit 90 includes, for example, voltage divider resistors 91 and 92 for dividing the combined electromotive force Vss, and a resistor 93 and capacitor 94 connected in parallel with first voltage divider resistor 91. Resistor 93 and capacitor 94 form a filter circuit that reduces noise contained in the combined electromotive force Vss.

[0088] The voltage amplifier circuit 100 includes a feedback operational amplifier 101 , a first amplifying resistor 102 , and a second amplifying resistor 103 .

[0089] The feedback operational amplifier 101 is provided on the second local line 43b. The + terminal of the feedback operational amplifier 101 is connected to the voltage divider circuit 90 via the second local line 43b. The combined electromotive force Vss divided by the voltage divider circuit 90 is input to the + terminal of the feedback operational amplifier 101.

[0090] The output terminal of the feedback operational amplifier 101 is connected to the adding circuit 60 (specifically, the external input line 41 ) via the second local line 43 b . The resultant electromotive force Vss output from the output terminal of the feedback operational amplifier 101 is transmitted through the second local line 43 b and input to the adding circuit 60 .

[0091] The output terminal of the feedback operational amplifier 101 is connected to the -terminal (inverting input terminal) of the feedback operational amplifier 101 via the first amplifying resistor 102. Furthermore, the second amplifying resistor 103 is connected to the connection line between the first amplifying resistor 102 and the -terminal of the feedback operational amplifier 101 and is connected to the reference potential V0. In other words, the voltage amplifier circuit 100 of this embodiment is a non-inverting amplifier circuit.

[0092] According to the above configuration, the combined electromotive force Vss input to the feedback input terminal 33 is divided by the voltage divider circuit 90 and amplified by the voltage amplifier circuit 100. The amplification factor of the voltage amplifier circuit 100 is arbitrary and may be 1, greater than 1, or less than 1.

[0093] In this embodiment, impedance conversion is performed by the voltage amplifier circuit 100. Specifically, the impedance on the input side of the feedback operational amplifier 101 is higher than the impedance on the output side of the feedback operational amplifier 101. This limits the flow of a portion of the first drain current Id1 into the two detection terminals 24a and 24b, the feedback input terminal 33, and the common connection line 43.

[0094] The power conversion device 10 includes an inverter circuit 110 that inverts the combined electromotive force Vss. The inverter circuit 110 is provided in, for example, the lower arm drive circuit 12y, and more specifically, is provided on the second local line 43b.

[0095] The inverting circuit 110 reverses the polarity of the resultant electromotive force Vss. Specifically, the inverting circuit 110 converts the resultant electromotive force Vss to a negative voltage (-) when it is positive (+), and to a positive voltage when it is negative. In this embodiment, the absolute value of the resultant electromotive force Vss is not changed by the inverting circuit 110. The specific configuration of the inverting circuit 110 is arbitrary.

[0096] The lower arm drive circuit 12y includes an external input resistor 111 provided on the external input line 41, and a feedback input resistor 112 provided on the common connection line 43. The external input resistor 111 is provided at the portion of the external input line 41 that connects the filter circuit 50 and the adder circuit 60. The feedback input resistor 112 is provided at the portion of the second local line 43b of the common connection line 43 that connects the voltage amplifier circuit 100 and the adder circuit 60.

[0097] use Figure 4 The operation of this embodiment will be described using the turning-on of the lower arm switching elements 11ya and 11yb as an example. Figure 4 (a) is a timing diagram showing the change of the external command voltage Vp. Figure 4 (b) schematically shows the waveform of the synthetic electromotive force Vss. Figure 4 (c) is a graph showing the waveform of the first drain current Id1. Figure 4 (d) is a graph showing the waveform of the second drain current Id2. In this embodiment, a case where the timings of the peaks of the first drain current Id1 and the second drain current Id2 are different will be described.

[0098] like Figure 4 As shown in (a) of FIG. 1 , at time t1 , the external command voltage Vp increases. As a result, the increase in the external command voltage Vp is input to both lower arm switching elements 11 ya and 11 yb at the same time.

[0099] Here, the two lower arm switching elements 11ya and 11yb may have individual element characteristics. Therefore, even if the external command voltage Vp rises simultaneously in both lower arm switching elements 11ya and 11yb, the rising timings of the two drain currents Id1 and Id2 may differ.

[0100] For example, Figure 4 (c) and Figure 4 As shown in (d), at time t2, the first drain current Id1 starts to flow before the second drain current Id2. In this case, the first back electromotive force Vb1 is generated by the start of the flow of the first drain current Id1. Figure 4 As shown in (b) of FIG. 6 , a composite electromotive force Vss is generated, and the composite electromotive force Vss is fed back to the adding circuit 60 .

[0101] Furthermore, the first back electromotive force Vb1 generated by the start of the flow of the first drain current Id1 becomes a positive voltage. The resultant electromotive force Vss, after being divided by the voltage divider circuit 90 and amplified by the voltage amplifier circuit 100, is then inverted in polarity by the inverter circuit 110 and input to the adder circuit 60. This input of the negative resultant electromotive force Vss to the adder circuit 60 reduces the slope of the first drain current Id1 and slows its rise. Furthermore, the resultant electromotive force Vss in this situation is approximately half the value of the first back electromotive force Vb1.

[0102] Then, if Figure 4 As shown in (d), at time t3, the second drain current Id2 begins to flow. The start of the flow of the second drain current Id2 generates a second back electromotive force Vb2. Furthermore, the combined electromotive force Vss of the first back electromotive force Vb1 and the second back electromotive force Vb2 is fed back, thereby slowing the rise of both drain currents Id1 and Id2. Specifically, the slopes of the two drain currents Id1 and Id2 are smaller than when only the first drain current Id1 flows. More specifically, the slopes of the two drain currents Id1 and Id2 are approximately half the slope of the first drain current Id1 during the period t2-t3.

[0103] like Figure 4 As shown in (c) of FIG. 3 , at time t4 , when the first drain current Id1 reaches its peak, the first drain current Id1 starts to decrease, thereby generating a first back electromotive force Vb1 in the opposite direction to that in the period t2 - t4 .

[0104] On the other hand, at time t4, since the second drain current Id2 is rising, the second back electromotive force Vb2 is generated. Figure 4 As shown in (b), the combined electromotive force Vss cancels each other and becomes "0" or a value close to "0".

[0105] Then, if Figure 4 As shown in (c), at time t5, the first drain current Id1 reaches the saturation current and is maintained at the saturation current. The saturation current can also be said to be the current that stably flows when the first lower arm switching element 11ya is in the on state.

[0106] Here, the first drain current Id1 becomes a saturated current and the first back electromotive force Vb1 becomes "0". Figure 4 As shown in (b), the synthetic electromotive force Vss corresponding to the second counter electromotive force Vb2 is fed back. Therefore, the surge suppression effect caused by the feedback of the synthetic electromotive force Vss continues. Figure 4 The excessive increase of the second drain current Id2 as indicated by the two-dot chain line in (d) is suppressed.

[0107] For the sake of caution, the actual period from t4 to t5 is a very short period, and therefore the influence of the resultant electromotive force Vss becoming "0" is negligibly small.

[0108] Moreover, if Figure 4 As shown in (d) of FIG. 3 , at time t6, when the second drain current Id2 reaches its peak, the second drain current Id2 begins to decrease. As a result, a second back electromotive force Vb2 is generated that is opposite to that during the period t3-t6. Figure 4 As shown in (b) of FIG. 1 , a reverse-direction combined electromotive force Vss is generated. Then, at time t7, the second drain current Id2 becomes a saturation current, and the combined electromotive force Vss becomes "0".

[0109] As described above, in this embodiment, even when the rising timing of the two lower arm switching elements 11ya and 11yb (specifically, the timing at which the drain currents Id1 and Id2 start to flow) is different due to element deviation, etc., feedback based on the synthetic electromotive force Vss is performed throughout the period from when the two drain currents Id1 and Id2 reach their peak values.

[0110] The same applies when lower arm switching elements 11ya and 11yb are off. Specifically, when lower arm switching elements 11ya and 11yb are off, drain currents Id1 and Id2 begin to decrease, generating negative back electromotive forces Vb1 and Vb2 via inductance components L1 and L2. The combined electromotive force Vss of the two back electromotive forces Vb1 and Vb2 is divided by voltage divider circuit 90, amplified by voltage amplifier circuit 100, and then input to adder circuit 60 after its polarity is reversed by inverter circuit 110. In this case, even if there is a deviation in the decreasing patterns of drain currents Id1 and Id2, the combined electromotive force Vss is fed back until both drain currents Id1 and Id2 reach "0."

[0111] The turning on and off of the upper arm switching elements 11xa and 11xb are similar to the turning on and off of the lower arm switching elements 11ya and 11yb, and therefore, detailed description of their operations will be omitted.

[0112] The present embodiment described above achieves the following effects. For ease of explanation, the first switching elements 11uua, 11uda, 11vua, 11vda, 11wua, and 11wda are referred to as first switching elements 11a, and the second switching elements 11uub, 11udb, 11vub, 11vdb, 11wub, and 11wdb are referred to as second switching elements 11b.

[0113] (1) A power conversion device 10 includes a first switching element 11a, which flows a first drain current Id1 as a first applied current when in an on state; and a second switching element 11b, which is connected in parallel with the first switching element 11a and flows a second drain current Id2 as a second applied current when in an on state. The power conversion device 10 includes a drive circuit 12 for driving the two switching elements 11a and 11b.

[0114] Switching elements 11a and 11b include gate terminals 21a and 21b serving as control terminals, and detection terminals 24a and 24b for detecting back electromotive forces Vb1 and Vb2 generated by inductance components L1 and L2, including parasitic inductances Ls1 and Ls2. Drive circuit 12 includes an external input terminal 31 for inputting an external command voltage Vp, an adding circuit 60 for outputting a summed voltage Vad, and an adding output terminal 32 for outputting this summed voltage.

[0115] In the above-described configuration, power converter 10 includes a control line 42 connecting summing output terminal 32 to gate terminals 21a and 21b, and a common connection line 43 connecting detection terminals 24a and 24b to each other and to summing circuit 60, transmitting a combined electromotive force Vss of the two back electromotive forces Vb1 and Vb2. Adding circuit 60 receives an external command voltage Vp, which is an input of combined electromotive force Vss, and outputs a summed voltage Vad by adding the combined electromotive force Vss to the external command voltage Vp.

[0116] According to the above configuration, the two switching elements 11a and 11b connected in parallel operate based on the summed voltage Vad. Thus, the two switching elements 11a and 11b operate synchronously, allowing a current to flow that is the sum of the two drain currents Id1 and Id2. Consequently, a larger current can flow compared to a case where a single switching element is used. Furthermore, according to this configuration, since the two switching elements 11a and 11b operate based on the summed voltage Vad, which is fed back as the combined electromotive force Vss, both power loss and surge suppression can be achieved.

[0117] In particular, according to this configuration, the two detection terminals 24a and 24b are connected to each other via a common connection line 43, and the two detection terminals 24a and 24b are also connected to the adding circuit 60. Consequently, the combined electromotive force Vss of the two back electromotive forces Vb1 and Vb2 is used as the voltage fed back to the adding circuit 60. Therefore, even if there is a deviation in the operation of the two switching elements 11a and 11b, feedback can be applied to the two switching elements 11a and 11b, achieving both reduction in power loss and suppression of surges.

[0118] As described in detail below, for example, when feeding back the back electromotive force while controlling two switching elements 11a and 11b connected in parallel with each other with the same added voltage Vad, it is sufficient to feed back the back electromotive force generated by either of the two switching elements 11a and 11b. Therefore, it is generally considered that the voltage fed back to the adding circuit 60 is not the resultant electromotive force Vss, but rather one of the two back electromotive forces Vb1 and Vb2.

[0119] Here, there is a possibility that the two switching elements 11a and 11b may have element variations. Therefore, even if the same added voltage Vad is input to the two gate terminals 21a and 21b, there may be variations in the operation of the two switching elements 11a and 11b.

[0120] The inventors of the present application have discovered that, when such a deviation occurs, if the back electromotive force generated by one of the two switching elements 11a and 11b is fed back, the effect of the feedback may not be obtained in either switching element 11a or 11b.

[0121] For example, when the first back electromotive force Vb1 is used as the voltage fed back to the adding circuit 60, Figure 4 As shown by the double-dashed line in (b), at time t4, the fed-back voltage becomes in the opposite direction and then becomes "0" at time t5. Then, the feedback based on the back electromotive force disappears, so Figure 4 As shown by the two-dot chain line in (d), the second drain current Id2 increases excessively. In this case, there is a possibility that the operation of the second switching element 11b is hindered.

[0122] Regarding this point, according to this configuration, the voltage fed back to the adding circuit 60 becomes the resultant electromotive force Vss. Therefore, as described above, even if there is a deviation in the operation of the two switching elements 11a and 11b, feedback based on the back electromotive force can be provided to both switching elements 11a and 11b. This can thus suppress the aforementioned disadvantages. Therefore, in a configuration in which the two switching elements 11a and 11b are connected in parallel, it is possible to simultaneously achieve reduced power loss and surge suppression.

[0123] (2) The drive circuit 12 includes a feedback input terminal 33 for inputting the resultant electromotive force Vss. The common connection line 43 includes a first local line 43a that connects the two detection terminals 24a and 24b and connects the two detection terminals 24a and 24b to the feedback input terminal 33; and a second local line 43b that is provided within the drive circuit 12 and connects the feedback input terminal 33 to the adding circuit 60.

[0124] According to the above configuration, the two back electromotive forces Vb1 and Vb2 are synthesized via the first local line 43a, and this synthesized electromotive force Vss is input to the feedback input terminal 33. Furthermore, the synthesized electromotive force Vss is transmitted via the second local line 43b and input to the adder circuit 60. This achieves the above-described effects. Furthermore, according to this configuration, the drive circuit 12 does not need to have two feedback input terminals corresponding to the two back electromotive forces Vb1 and Vb2, thereby simplifying the structure of the drive circuit 12.

[0125] (3) The power conversion device 10 includes the voltage amplifier circuit 100 provided on the second local line 43 b and amplifying the combined electromotive force Vss.

[0126] According to the above configuration, the combined electromotive force Vss is amplified by the voltage amplifier circuit 100 and then input to the adding circuit 60. Thus, even when the voltage generated by the two inductance components L1 and L2 is small, a combined electromotive force Vss of a desired magnitude can be input to the adding circuit 60.

[0127] (4) The power conversion device 10 includes a first upper arm switching element 11xa and a second upper arm switching element 11xb, and a first lower arm switching element 11ya and a second lower arm switching element 11yb as the first switching element 11a and the second switching element 11b. The parallel connection of the two upper arm switching elements 11xa and 11xb and the parallel connection of the two lower arm switching elements 11ya and 11yb are connected in series.

[0128] The power conversion device 10 includes a positive bus LN1 connecting two upper arm switching elements 11xa and 11xb, and a negative bus LN2 connecting two lower arm switching elements 11ya and 11yb. Negative bus LN2 is connected to a reference potential V0. The power conversion device 10 includes an upper arm drive circuit 12x that drives the two upper arm switching elements 11xa and 11xb, and a lower arm drive circuit 12y that drives the two lower arm switching elements 11ya and 11yb as a drive circuit 12. A common connection line 43 connects the detection terminals 24a and 24b of the two lower arm switching elements 11ya and 11yb to each other and connects the two detection terminals 24a and 24b to the lower arm drive circuit 12y.

[0129] Here, the back electromotive forces Vb1 and Vb2 applied to the detection terminals 24a and 24b of the lower arm switching elements 11ya and 11yb are positive voltages when the lower arm switching elements 11ya and 11yb are on, and are negative voltages when the lower arm switching elements 11ya and 11yb are off. Specifically, the detection terminals 24a and 24b of the lower arm switching elements 11ya and 11yb are connected between the main bodies of the lower arm switching elements 11ya and 11yb and the parasitic inductances Ls1 and Ls2.

[0130] The power conversion device 10 includes an inverter circuit 110 provided on the common connection line 43 and configured to invert the combined electromotive force Vss. The combined electromotive force Vss inverted by the inverter circuit 110 is input to the adding circuit 60 .

[0131] According to the above structure, under the conditions that the negative bus LN2 is connected to the reference potential V0, and positive voltage back electromotive force Vb1, Vb2 is applied when connected and negative voltage back electromotive force Vb1, Vb2 is applied when disconnected, feedback using back electromotive force Vb1, Vb2 can be performed on the two lower arm switching elements 11ya, 11yb.

[0132] (Second embodiment)

[0133] In this embodiment, the structure of the switching element 11 of the power conversion device 10 and the connection method of the feedback input terminal 33 of the power conversion device 10 and the drive circuit 12 are different from those of the first embodiment. Figure 5 The differences from the first embodiment will be described.

[0134] like Figure 5 As shown, the switching element 11 of the power conversion device 10 of the present embodiment has the same structure as the switching element 11 of the first embodiment except that it does not include a detection terminal.

[0135] The first source terminal 23 a of the first lower arm switching element 11 ya and the second source terminal 23 b of the second lower arm switching element 11 yb function as output terminals.

[0136] Hereinafter, description will be given assuming that the first source terminal 23 a of the first lower arm switching element 11 ya is a first output terminal, and the second source terminal 23 b of the second lower arm switching element 11 yb is a second output terminal.

[0137] The power conversion device 10 includes a detection line 43A having an inductance L and connecting the first output terminal of the first lower arm switching element 11 ya and the second output terminal of the second lower arm switching element 11 yb .

[0138] The inductor L is an inductor that generates a counter electromotive force Vb due to the change in the combined current of the first drain current Id1 and the second drain current Id2 , and may be formed by a coil or a parasitic inductor Ls.

[0139] The detection line 43A connects two output terminals (a first output terminal and a second output terminal) to the adding circuit 60 so that the back electromotive force Vb generated by the inductance L is input to the adding circuit 60 .

[0140] The detection line 43A of this embodiment is a wiring pattern formed on the circuit board and is connected to the feedback input terminal 33 of the drive circuit 12. The detection line 43A is connected to the reference potential V0 similarly to the negative bus LN2.

[0141] According to the present embodiment described in detail above, in addition to the same effects as those of the first embodiment, the following effects are also achieved.

[0142] (5) The power conversion device 10 includes: a detection line 43A having an inductance L, connecting the first output terminal of the first lower arm switching element 11ya and the second output terminal of the second lower arm switching element 11yb, and connecting the two output terminals (the first output terminal and the second output terminal) to the adding circuit 60 in a manner that inputs the back electromotive force Vb generated by the inductance L to the adding circuit 60.

[0143] According to the above configuration, similar to the first embodiment, even if there is a deviation in the operation of the two switching elements 11a and 11b, feedback can be applied to the two switching elements 11a and 11b, thereby achieving both reduction in power loss and suppression of surges. In addition, there is no need to provide a detection terminal on the switching element 11.

[0144] (6) The power conversion device 10 includes the voltage amplifier circuit 100 that amplifies the back electromotive force Vb.

[0145] According to the above configuration, the counter electromotive force Vb is amplified by the voltage amplifier circuit 100 and then input to the adding circuit 60. Thus, even when the voltage generated by the inductor L is small, a counter electromotive force Vb of a desired magnitude can be input to the adding circuit 60.

[0146] (Other examples)

[0147] Furthermore, the above-described embodiments may be modified as follows: Furthermore, the above-described embodiments and the following other examples may be appropriately combined within a range that does not technically conflict.

[0148] ○ Such as Figure 6 As shown, the lower arm drive circuit 12y may also have a structure including a first feedback input terminal 33a for inputting the first back electromotive force Vb1, and a second feedback input terminal 33b for inputting the second back electromotive force Vb2. In this case, the common connection line 43 may also include a first line 121 connecting the first detection terminal 24a and the first feedback input terminal 33a, and a second line 122 connecting the second detection terminal 24b and the second feedback input terminal 33b. Furthermore, the common connection line 43 may include a third line 123 provided in the lower arm drive circuit 12y, connecting the two feedback input terminals 33a and 33b to each other and connecting the two feedback input terminals 33a and 33b to the adding circuit 60. According to this structure, effects such as (1) are also achieved.

[0149] The location of the inverter circuit 110 is arbitrary. For example, the inverter circuit 110 can be located at the connection between the feedback input terminal 33 of the second local line 43b and the voltage divider circuit 90, or it can be located on the first local line 43a. Furthermore, the inverter circuit 110 can be located on the common connection line 43, either upstream (on the input side) or downstream (on the output side) of the voltage amplifier circuit 100.

[0150] In the above embodiment, two switching elements 11a and 11b are connected in parallel, but the present invention is not limited thereto and three or more switching elements may be connected in parallel. In this case as well, the power converter 10 includes the first switching element 11a and the second switching element 11b.

[0151] Switching element 11 is not limited to a MOSFET; it can also be an IGBT, for example. In this case, the gate terminal of switching element 11 corresponds to the "control terminal," and the collector current flowing between the collector and emitter of switching element 11 corresponds to the "applied current." Furthermore, the emitter terminal can also be considered the applied terminal through which the applied current flows.

[0152] ○ The current amplifier circuit 70 may be omitted.

[0153] ○ The filter circuit 50 may be omitted.

[0154] The voltage divider circuit 90 may be omitted. That is, the combined electromotive force Vss input to the adding circuit 60 may be a divided electromotive force or an undivided electromotive force.

[0155] The voltage amplifier circuit 100 can be an inverting amplifier circuit. In this case, the voltage amplifier circuit 100 constitutes an "inverting circuit." Therefore, the inverting circuit 110 can be omitted. In other words, the "inverting circuit" can be provided separately from the "voltage amplifier circuit," or the inverting amplifier circuit can also have an amplification function.

[0156] The voltage amplifier circuit 100 may be omitted. In other words, the combined electromotive force Vss input to the adding circuit 60 may be amplified or not.

[0157] Each switching element 11 constitutes an inverter, but this is not limiting. Any type of device is acceptable. For example, it may constitute a DC / DC converter that converts the DC power from the power storage device 203 into DC power of a different voltage. In other words, the power conversion device 10 is not limited to an inverter and may be any type of device, such as a DC / DC converter, an AC / AC converter, or an AC / DC inverter. In other words, the power conversion device 10 may convert DC power or AC power into DC power or AC power.

[0158] The load is not limited to the electric motor 201 and can be any load.

[0159] The power conversion device 10 may be mounted on a device other than the vehicle 200 . In other words, the power conversion device 10 may be a device that drives a load other than the load installed on the vehicle 200 .

[0160] Next, a preferred example that can be grasped from the above-mentioned embodiment and other examples will be described below.

[0161] (A) The power conversion device may include a voltage amplifier circuit provided on the common connection line, and the inverter circuit may be provided before or after the voltage amplifier circuit on the common connection line.

[0162] (B) The above-mentioned inverting circuit may be an inverting amplifier circuit.

[0163] Description of Reference Signs

[0164] 10…Power conversion device, 11…Switching element, 11a…First switching element, 11b…Second switching element, 11xa…First upper-arm switching element, 11xb…Second upper-arm switching element, 11ya…First lower-arm switching element, 11yb…Second lower-arm switching element, 12…Drive circuit, 12x…Upper-arm drive circuit, 12y…Lower-arm drive circuit, 21a…First gate terminal (first control terminal), 21b…Second gate terminal (second control terminal), 24a…First detection terminal, 24b…Second detection terminal, 31…External input terminal, 32…Addition output terminal, 33, 33a, 33b…Feedback input terminal, 42…Control line, 43…Common connection line, 43a…First local Line, 43b…second local line, 43A…detection line, 60…adding circuit, 70…current amplifying circuit, 90…voltage dividing circuit, 100…voltage amplifying circuit, 110…inverting circuit, 200…vehicle, 201…electric motor (load), 203…power storage device, Vp…external command voltage, Vb1…first back electromotive force, Vb2…second back electromotive force, Vss…synthetic electromotive force, Vad…added voltage, V0…reference potential, Ls1…first parasitic inductance, Ls2…second parasitic inductance, Ls…parasitic inductance, L1…first inductance component, L2…second inductance component, L…inductance, Id1…first drain current, Id2…second drain current, LN1…positive bus, LN2…negative bus

Claims

1. A power conversion device comprising: a first switching element, which, when in an on state, allows a first applied current to flow; a second switching element connected in parallel with the first switching element and allowing a second applied current to flow when in an on state; and a driving circuit for driving the first switching element and the second switching element, The power conversion device is characterized in that: The first switching element includes: a first control terminal; a first parasitic inductance through which the first applied current flows; and a first detection terminal for detecting a first back electromotive force generated by a first inductance component including a first parasitic inductance; The second switching element includes: a second control terminal; a second parasitic inductance through which the second applied current flows; and a second detection terminal for detecting a second back electromotive force generated by a second inductance component including the second parasitic inductance; The above-mentioned driving circuit has: External input terminal, for external command voltage input; an adding circuit that outputs a summed voltage; and The summing output terminal is used to output the summing voltage. The power conversion device includes: a control line connecting the addition output terminal to the first control terminal and the second control terminal; and a common connection line that connects the first detection terminal and the second detection terminal to each other and connects the first detection terminal and the second detection terminal to the adding circuit, and transmits a resultant electromotive force of the first back electromotive force and the second back electromotive force; The adding circuit receives the combined electromotive force and the external command voltage as inputs, and outputs the added voltage by adding the combined electromotive force and the external command voltage.

2. The power conversion device according to claim 1, wherein: The drive circuit includes a feedback input terminal for inputting the synthetic electromotive force. The above-mentioned common connection line has: a first local line connecting the first detection terminal and the second detection terminal to each other and connecting the first detection terminal and the second detection terminal to the feedback input terminal; and The second local line is provided in the driving circuit and connects the feedback input terminal to the adding circuit.

3. The power conversion device according to claim 2, comprising: The voltage amplifying circuit is provided on the second local line and amplifies the synthetic electromotive force.

4. The power conversion device according to any one of claims 1 to 3, wherein: As the first switching element and the second switching element, there are provided: a first upper arm switching element and a second upper arm switching element connected in parallel to each other; and a first lower arm switching element and a second lower arm switching element connected in parallel to each other, The parallel connection body of the first upper arm switching element and the second upper arm switching element and the parallel connection body of the first lower arm switching element and the second lower arm switching element are connected in series. The power conversion device includes: a positive bus bar connecting the first upper arm switching element and the second upper arm switching element; a negative bus bar connecting the first lower arm switching element and the second lower arm switching element and connected to a reference potential; and As the driving circuit, an upper arm driving circuit driving the first upper arm switching element and the second upper arm switching element, and a lower arm driving circuit driving the first lower arm switching element and the second lower arm switching element, When the first lower arm switching element and the second lower arm switching element are off, the first back electromotive force having a negative voltage is applied to the first detection terminal of the first lower arm switching element, and the second back electromotive force having a negative voltage is applied to the second detection terminal of the second lower arm switching element. The common connection line connects the first detection terminal and the second detection terminal of the first lower arm switching element and the second lower arm switching element to each other and connects the first detection terminal and the second detection terminal to the adding circuit of the lower arm driving circuit. The power conversion device includes an inverter circuit provided on the common connection line and configured to invert the synthetic electromotive force. The synthetic electromotive force inverted by the inverter circuit is input to the adding circuit.

5. A power conversion device comprising: a first switching element, which, when in an on state, allows a first applied current to flow; a second switching element connected in parallel with the first switching element and allowing a second applied current to flow when in an on state; and a driving circuit for driving the first switching element and the second switching element, The power conversion device is characterized in that: The first switching element includes: a first control terminal; and The first output terminal, The second switching element includes: a second control terminal; and The second output terminal, The above-mentioned driving circuit has: External input terminal, for external command voltage input; an adding circuit that outputs a summed voltage; and The summing output terminal is used to output the summing voltage. The power conversion device includes: a control line connecting the addition output terminal to the first control terminal and the second control terminal; and a detection line having an inductance, connecting the first output terminal and the second output terminal to each other and connecting the first output terminal and the second output terminal to the adding circuit so that a back electromotive force generated by the inductance is input to the adding circuit; The adding circuit receives the counter electromotive force and the external command voltage as inputs, and outputs the added voltage by adding the counter electromotive force and the external command voltage.

6. The power conversion device according to claim 5, characterized in that The detection line is a wiring pattern provided on the substrate.

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