JP7563334B2 - Power Conversion Equipment - Google Patents

Description

The present invention relates to a power conversion device.

Patent document 1 describes a driver circuit that drives an IGBT as a switching element. The driver circuit described in patent document 1 performs active gate control that feeds back the back electromotive force generated by the inductance component of the emitter wiring in order to achieve both a reduction in switching loss and a reduction in surge voltage or surge current.

JP 2004-48843 A

Here, when performing active gate control, the inductance component must have an inductance value that can generate at least a level of reverse voltage that can be used for active gate control.

In a power conversion device having multiple switching elements connected in series with each other, if an inductance component having an inductance value capable of generating a reverse voltage at a level that can be used for active gate control is provided for each switching element, the surge voltage and surge current may increase due to an increase in wiring inductance, or the device may become larger.

The power conversion device that achieves the above object includes a first switching element through which a first applied current flows, a second switching element that is connected in series with the first switching element and through which a second applied current flows, an inductance component that generates a back electromotive voltage in response to a change in the first applied current or a change in the second applied current, a first feedback circuit that converts the back electromotive voltage into a first feedback voltage, a second feedback circuit that converts an input voltage into a second feedback voltage, a current suppression unit that suppresses the first applied current and the second applied current from flowing into the second feedback circuit and outputs a voltage based on the back electromotive voltage to the second feedback circuit, a first driver circuit that drives the first switching element based on a first external command voltage, and a second driver circuit that drives the second switching element based on a second external command voltage, When the inductance component generates the back electromotive voltage due to a change in the first applied current, the first driver circuit adds the first external command voltage and the first feedback voltage and outputs the added sum voltage to the first switching element, the second driver circuit adds the second external command voltage and the second feedback voltage and outputs the added sum voltage to the second switching element, when the inductance component generates the back electromotive voltage due to a change in the second applied current, the first driver circuit adds the first external command voltage and the second feedback voltage and outputs the added sum voltage to the first switching element, and the second driver circuit adds the second external command voltage and the first feedback voltage and outputs the added sum voltage to the second switching element.

With this configuration, the power conversion device performs feedback control using a common inductance component on the first switching element and the second switching element, which are connected in series with each other. This allows the power conversion device to be miniaturized while simultaneously achieving a reduction in switching loss and a reduction in surge voltage or surge current.

In the above power conversion device, the inductance component may be realized by a parasitic inductance of wiring connected to the first switching element and/or the second switching element.

According to this configuration, the power conversion device can be made smaller by using the parasitic inductance, compared to a case in which a separate inductance is provided.
In a power conversion device that achieves the above-mentioned objective, the current suppression unit may include an inductor magnetically coupled to the inductance component, the inductor generating an electromotive voltage due to the back electromotive voltage generated by the inductance component, and the second feedback circuit may convert the electromotive voltage generated by the inductor into the second feedback voltage.

In a power conversion device that achieves the above object, the current suppression unit may include a differential amplifier circuit, the differential amplifier circuit receives the back electromotive force voltage at a pair of input terminals, amplifies the potential difference between the pair of input terminals, and outputs the amplified potential difference, and the second feedback circuit may convert the voltage output by the differential amplifier circuit into the second feedback voltage.

The present invention makes it possible to reduce the size of a power conversion device while simultaneously reducing switching losses and surge voltages or surge currents.

FIG. 1 is a diagram illustrating an example of a configuration of a power conversion device. FIG. 2 is a diagram showing details of various connections. FIG. 11 is a diagram showing other examples of various connections. FIG. 1 is a diagram illustrating an example of a differential amplifier circuit. FIG. 13 is a diagram illustrating another example of a differential amplifier circuit.

<Embodiment>
[Configuration of power conversion device 10]
An embodiment of a power conversion device will be described below. A 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.

In detail, 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 has three-phase coils 202u, 202v, and 202w. The three-phase coils 202u, 202v, and 202w are, for example, Y-connected. The electric motor 201 rotates when the three-phase coils 202u, 202v, and 202w are energized in a predetermined pattern. Note that the connection mode of the three-phase coils 202u, 202v, and 202w is not limited to Y-connection and may be any other connection, for example, a delta connection.

As shown in FIG. 1, the vehicle 200 has a power storage device 203. The power conversion device 10 of this embodiment is an inverter device that converts DC power from the power storage device 203 into AC power that can drive the electric motor 201. In other words, the power conversion device 10 can be said to be a drive device that drives the electric motor 201 using the power storage device 203.

The power conversion device 10 of this embodiment has configurations related to the three-phase coils 202u, 202v, and 202w of the electric motor 201. In the following explanation, of the various configurations provided in the power conversion device 10, the configurations related to the upper arm will be described with "a" added to the end of the reference numerals, and the configurations related to the lower arm will be described with "b" added to the end of the reference numerals. In addition, of the various configurations provided in the power conversion device 10, the configurations related to the u phase will be described with "u" added to the end of the reference numerals, the configurations related to the v phase will be described with "v" added to the end of the reference numerals, and the configurations related to the w phase will be described with "w" added to the end of the reference numerals.

The power conversion device 10 of this embodiment has a plurality of switching elements 11. In detail, the power conversion device 10 includes an upper arm switching element 11au and a lower arm switching element 11bu corresponding to the u-phase coil 202u, an upper arm switching element 11av and a lower arm switching element 11bv corresponding to the v-phase coil 202v, and an upper arm switching element 11aw and a lower arm switching element 11bw corresponding to the w-phase coil 202w.

In the following description, when the upper arm switching element 11au, the upper arm switching element 11av, and the upper arm switching element 11aw are not distinguished from one another, they will simply be referred to as "upper arm switching element 11a." When the lower arm switching element 11bu, the lower arm switching element 11bv, and the lower arm switching element 11bw are not distinguished from one another, they will simply be referred to as "lower arm switching element 11b." The upper arm switching element 11a is an example of a "first switching element," and the lower arm switching element 11b is an example of a "second switching element."

Each switching element 11 is, for example, a power switching element, and one example is a MOSFET. The switching element 11 has a freewheel diode D. In detail, the upper arm switching element 11au has a freewheel diode Dau, the upper arm switching element 11av has a freewheel diode Dav, and the upper arm switching element 11aw has a freewheel diode Daw. The lower arm switching element 11bu has a freewheel diode Dbu, the lower arm switching element 11bv has a freewheel diode Dbv, and the lower arm switching element 11bw has a freewheel diode Dbw. The anode of the freewheel diode D is connected to the source terminal of the switching element 11, and the cathode of the freewheel diode D is connected to the drain terminal of the switching element 11.

The upper arm switching element 11a and the lower arm switching element 11b are connected in series with each other. In particular, the source terminal of the upper arm switching element 11au and the drain terminal of the lower arm switching element 11bu are connected via intermediate wiring LC1u and LC2u. In particular, the intermediate wiring LC1u and the intermediate wiring LC2u each have a first end and a second end. The first end of the intermediate wiring LC1u is connected to the source terminal of the upper arm switching element 11au. The second end of the intermediate wiring LC2u is connected to the drain terminal of the lower arm switching element 11bu. The intermediate wiring LC3u connected to the u-phase coil 202u is connected to the intermediate wiring LC2u. The source terminal of the upper arm switching element 11av and the drain terminal of the lower arm switching element 11bv are connected via intermediate wiring LC1v and LC2v. In particular, the intermediate wiring LC1v and the intermediate wiring LC2v each have a first end and a second end. A first end of the intermediate wiring LC1v is connected to a source terminal of the upper arm switching element 11av. A second end of the intermediate wiring LC1v and a first end of the intermediate wiring LC2v are connected. A second end of the intermediate wiring LC2v and a drain terminal of the lower arm switching element 11bv are connected. A connection point of the intermediate wirings LC1v and LC2v and the v-phase coil 202v are connected by an intermediate wiring LC3v. A source terminal of the upper arm switching element 11aw and a drain terminal of the lower arm switching element 11bw are connected via intermediate wirings LC1w and LC2w. In detail, the intermediate wiring LC1w and the intermediate wiring LC2w each have a first end and a second end. A first end of the intermediate wiring LC1w is connected to a source terminal of the upper arm switching element 11aw. A second end of the intermediate wiring LC1w and a first end of the intermediate wiring LC2w are connected. A second end of the intermediate wiring LC2w and a drain terminal of the lower arm switching element 11bw are connected. The connection point between the intermediate wiring LC1w and LC2w and the w-phase coil 202w are connected by the intermediate wiring LC3w.

In the following description, when intermediate wiring LC1u, intermediate wiring LC1v, and intermediate wiring LC1w are not distinguished from one another, they are simply referred to as "intermediate wiring LC1." Furthermore, when intermediate wiring LC2u, intermediate wiring LC2v, and intermediate wiring LC2w are not distinguished from one another, they are simply referred to as "intermediate wiring LC2." Furthermore, when intermediate wiring LC3u, intermediate wiring LC3v, and intermediate wiring LC3w are not distinguished from one another, they are simply referred to as "intermediate wiring LC3."

The drain terminal of the upper arm switching element 11a is connected to the positive bus LN1, and the source terminal of the lower arm switching element 11b is connected to the negative bus LN2. The positive bus LN1 is connected to the positive terminal (+ terminal) which is the high voltage side of the storage device 203, and the negative bus LN2 is connected to the negative terminal (- terminal) which is the low voltage side of the storage device 203. This causes the DC voltage Vdc of the storage device 203 to be applied to the series connection of the upper arm switching element 11a and the lower arm switching element 11b.

The power conversion device 10 includes a driver circuit 12 that drives the switching element 11. The driver circuit 12 in this embodiment is a so-called gate driver circuit. The power conversion device 10 in this embodiment includes a plurality of driver circuits 12 corresponding to the plurality of switching elements 11. In detail, the upper arm switching element 11au includes a driver circuit 12au, and the lower arm switching element 11bu includes a driver circuit 12bu. The upper arm switching element 11av includes a driver circuit 12av, and the lower arm switching element 11bv includes a driver circuit 12bv. The upper arm switching element 11aw includes a driver circuit 12aw, and the lower arm switching element 11bw includes a driver circuit 12bw. In the following description, when the driver circuits 12au, 12av, and 12aw are not to be distinguished from one another, they are simply referred to as "upper arm driver circuit 12a". Furthermore, when the driver circuits 12bu, 12bv, and 12bw are not to be distinguished from one another, they will simply be referred to as the "lower arm driver circuit 12b." The upper arm driver circuit 12a is an example of a "first driver circuit," and the lower arm driver circuit 12b is an example of a "second driver circuit."

The power conversion device 10 includes a conversion control device 14 that controls each driver circuit 12. In this embodiment, the conversion control device 14 is an inverter control device. The conversion control device 14 determines a target current that flows through the electric motor 201 based on an external command (e.g., a required rotation speed), and derives an external command voltage for the target current to flow. The conversion control device 14 then outputs the external command voltage to the driver circuit 12.

In this embodiment, the conversion control device 14 derives an external command voltage for each driver circuit 12 and outputs the external command voltage to each driver circuit. This allows the switching elements 11 to be individually controlled. In the following description, the external command voltage that the conversion control device 14 outputs to the upper arm driver circuit 12a is also referred to as the "first external command voltage," and the external command voltage that the conversion control device 14 outputs to the lower arm driver circuit 12b is also referred to as the "second external command voltage."

The power conversion device 10 includes a first feedback circuit 15 that feedback controls the upper arm switching element 11a, and an inductance component 16 for each phase. More specifically, the power conversion device 10 includes first feedback circuits 15u, 15v, and 15w, and inductance components 16u, 16v, and 16w. In the following description, when the first feedback circuits 15u, 15v, and 15w are not distinguished from one another, they are simply referred to as "first feedback circuit 15," and when the inductance components 16u, 16v, and 16w are not distinguished from one another, they are simply referred to as "inductance component 16."

The inductance component 16 generates a back electromotive voltage in response to changes in the applied current flowing through the switching element 11, and has an inductance value that can generate a back voltage at least at a level that can be used for feedback control. In this embodiment, the inductance component 16 is an inductor.

The power conversion device 10 also includes a current suppression unit 17 and a second feedback circuit 18 for feedback control of the lower arm switching element 11b for each phase. The current suppression unit 17 includes, for example, an inductor 19 magnetically coupled to the inductance component 16 and connection lines LJ3 and LJ4 connecting the second feedback circuit 18. In the inductor 19, an electromotive voltage Vd' is generated by a back electromotive voltage Vd generated by a change in the applied current flowing through the inductance component 16. The electromotive voltage Vd' generated in the inductor 19 is output to the second feedback circuit 18 via the connection lines LJ3 and LJ4. Details of the connection lines LJ3 and LJ4 connecting the second feedback circuit 18 and the inductor 19 will be described later.

The electromotive voltage Vd' generated in the inductor 19 is input to the second feedback circuit 18. The second feedback circuit 18 converts the input electromotive voltage Vd' into a second feedback voltage and outputs it to the lower arm driver circuit 12b. In detail, the power conversion device 10 includes current suppression units 17u, 17v, and 17w. The current suppression unit 17u includes an inductor 19u, the current suppression unit 17v includes an inductor 19v, and the current suppression unit 17w includes an inductor 19w. The power conversion device 10 also includes second feedback circuits 18u, 18v, and 18w. In the following description, when the current suppression units 17u, 17v, and 17w are not distinguished from one another, they are simply referred to as "current suppression unit 17". When the second feedback circuits 18u, 18v, and 18w are not distinguished from one another, they are simply referred to as "second feedback circuit 18". Furthermore, when inductors 19u, 19v, and 19w are not to be distinguished from one another, they will simply be referred to as "inductor 19."

[Details of various connections]
2, detailed descriptions will be given of connections among the upper arm driver circuit 12a, the lower arm driver circuit 12b, the first feedback circuit 15, the inductance component 16, the current suppression unit 17, and the second feedback circuit 18. Since these connections are similar for each phase, in the following description, the suffixes corresponding to each phase will be omitted.

As shown in FIG. 2, the upper arm switching element 11a is a switching element through which a first drain current Id1 flows when in the ON state. The first drain current Id1 is a current that flows between the source and drain of the upper arm switching element 11a. The upper arm switching element 11a has a gate terminal to which a gate voltage is input, and a drain terminal and a source terminal through which the first drain current Id1 flows when in the ON state.

The lower arm switching element 11b is a switching element through which a second drain current Id2 flows when in the ON state. The second drain current Id2 is a current that flows between the source and drain of the lower arm switching element 11b. The lower arm switching element 11b has a gate terminal to which a gate voltage is input, and a drain terminal and a source terminal through which the second drain current Id2 flows when in the ON state.

The upper arm driver circuit 12a is connected to the gate terminal of the upper arm switching element 11a. The upper arm driver circuit 12a outputs a gate voltage to the upper arm switching element 11a based on a first external command voltage, and controls the upper arm switching element 11a to an ON state or an OFF state. The lower arm driver circuit 12b is connected to the gate terminal of the lower arm switching element 11b. The lower arm driver circuit 12b outputs a gate voltage to the lower arm switching element 11b based on a second external command voltage, and controls the lower arm switching element 11b to an ON state or an OFF state.

The first feedback circuit 15 and the inductance component 16 are connected. The first feedback circuit 15 has a pair of input terminals, and the inductance component 16 has a pair of connection terminals. More specifically, the first feedback circuit 15 has a first input terminal tc1 and a second input terminal tc2. The inductance component 16 has a first connection terminal t1 and a second connection terminal t2. The first input terminal tc1 and the first connection terminal t1 are connected by a connection line LJ1. The second input terminal tc2 and the second connection terminal t2 are connected by a connection line LJ2.

The inductance component 16 is provided between the upper arm switching element 11a and the lower arm switching element 11b so that the first drain current Id1 flows. In detail, the first connection terminal t1 of the inductance component 16 is connected to the source terminal of the upper arm switching element 11a via the first intermediate wiring LC1, and the second connection terminal t2 of the inductance component 16 is connected to the drain terminal of the lower arm switching element 11b via the second intermediate wiring LC2. The third intermediate wiring LC3, which is connected to any one of the three-phase coils 202u, 202v, 202w, is connected to the second intermediate wiring LC2.

In this embodiment, the inductance component 16 generates a back electromotive voltage Vd across the connection terminals t1 and t2 in response to a change in the first drain current Id1. A change in the first drain current Id1 includes a case where the first drain current Id1 starts to flow through the inductance component 16 and a case where the first drain current Id1 that had been flowing through the inductance component 16 stops. The back electromotive voltage Vd is generated in a direction in which the potential of the first connection terminal t1 becomes higher than the potential of the second connection terminal t2. The first drain current Id1 is an example of a "first applied current."

The back electromotive voltage Vd generated by the inductance component 16 due to a change in the first drain current Id1 is input to the input terminals tc1 and tc2 of the first feedback circuit 15. The first feedback circuit 15 and the upper arm driver circuit 12a are connected. The first feedback circuit 15 converts the back electromotive voltage Vd into a first feedback voltage and outputs it to the upper arm driver circuit 12a.

The first feedback circuit 15 may be composed of wiring only. In this case, the first feedback circuit 15 converts the back electromotive voltage Vd into a voltage that is slightly lower than the back electromotive voltage Vd due to wiring resistance or the like, and outputs the voltage to the upper arm driver circuit 12a.

In this embodiment, the upper arm driver circuit 12a adds the first external command voltage and the first feedback voltage, and outputs the resulting sum voltage as the gate voltage to the upper arm switching element 11a.

The second feedback circuit 18 and the inductor 19 are connected. The second feedback circuit 18 has a pair of input terminals, and the inductor 19 has a pair of connection terminals. More specifically, the second feedback circuit 18 has a first input terminal td1 and a second input terminal td2. The inductor 19 has a first connection terminal t3 and a second connection terminal t4. The first input terminal td1 and the first connection terminal t3 are connected by a connection line LJ3. The second input terminal td2 and the second connection terminal t4 are connected by a connection line LJ4.

In this embodiment, as described above, the inductor 19 of the current suppression unit 17 is magnetically coupled to the inductance component 16. The inductance component 16 and the inductor 19 function as an insulating transformer. Therefore, the first drain current Id1 flowing through the inductance component 16 does not flow into the second feedback circuit 18. That is, the current suppression unit 17 blocks the first drain current Id1 from flowing into the second feedback circuit 18 and suppresses the first drain current Id1 from flowing into the second feedback circuit 18. In addition, the inductor 19 generates an electromotive voltage Vd' due to the back electromotive voltage Vd generated by the inductance component 16, and the electromotive voltage Vd' is output to the second feedback circuit 18 via the connection lines LJ3 and LJ4. That is, the current suppression unit 17 outputs a voltage based on the back electromotive voltage (electromotive voltage Vd' in this embodiment) to the second feedback circuit 18. For example, the electromotive voltage Vd' is generated in a direction such that the potential of the first connection terminal t3 is higher than the potential of the second connection terminal t4.

In addition, the inductor 19 in this embodiment has a number of turns set so as to output an electromotive voltage Vd' having a voltage value different from the back electromotive voltage Vd to the second feedback circuit 18, but this is not limited to this. The inductor 19 may have a number of turns set so as to output an electromotive voltage having the same voltage value as the back electromotive voltage Vd to the second feedback circuit 18.

The electromotive voltage Vd' is input to the input terminals tc1 and tc2 of the second feedback circuit 18. The second feedback circuit 18 and the lower arm driver circuit 12b are connected. The second feedback circuit 18 converts the input electromotive voltage Vd' into a second feedback voltage and outputs it to the lower arm driver circuit 12b. Here, the second feedback voltage may be the same voltage value as the first feedback voltage, or may be a different voltage value.

The second feedback circuit 18 may be composed of wiring only. In this case, the inductor 19 converts the back electromotive force Vd to a voltage slightly higher than the second feedback voltage and outputs it to the second feedback circuit 18. The second feedback circuit 18 converts the input voltage slightly higher than the second feedback voltage into the second feedback voltage using wiring resistance or the like and outputs it to the lower arm driver circuit 12b.

In this embodiment, the lower arm driver circuit 12b adds the second external command voltage and the second feedback voltage, and outputs the resulting sum voltage as the gate voltage to the lower arm switching element 11b.

[Effects of the power conversion device 10]
(1) In the power conversion device 10, the first feedback circuit 15 converts the back electromotive voltage Vd generated by the inductance component 16 into a first feedback voltage. The current suppression unit 17 suppresses (more specifically, blocks) the first drain current Id1 from flowing into the second feedback circuit 18, and outputs a voltage based on the back electromotive voltage Vd (electromotive voltage Vd' in this embodiment) to the second feedback circuit 18. The second feedback circuit 18 converts the input electromotive voltage Vd' into a second feedback voltage. The upper arm driver circuit 12a adds the first external command voltage and the first feedback voltage, and outputs the added voltage to the upper arm switching element 11a. The lower arm driver circuit 12b adds the second external command voltage and the second feedback voltage, and outputs the added voltage to the lower arm driver circuit 12b.

Here, the feedback control of the first feedback circuit 15 and the feedback control of the second feedback circuit 18 are synchronized. For example, in response to a change in the first drain current Id1, the first feedback circuit 15 may perform feedback control to lower the gate voltage of the upper arm switching element 11a by a predetermined voltage for a predetermined period. In this case, it is preferable that the second feedback circuit 18 performs feedback control to lower the gate voltage of the lower arm switching element 11b by a predetermined voltage for a predetermined period at the same timing as the first feedback circuit 15. Also, the first feedback circuit 15 may perform feedback control to raise the gate voltage of the upper arm switching element 11a by a predetermined voltage for a predetermined period. In this case, it is preferable that the second feedback circuit 18 performs feedback control to raise the gate voltage of the lower arm switching element 11b by a predetermined voltage for a predetermined period at the same timing as the first feedback circuit 15.

On the other hand, if the first drain current Id1 is input to the second feedback circuit 18 without being suppressed, the second feedback circuit 18 may be damaged. In the power conversion device 10 configured as described above, the first feedback circuit 15 converts the back electromotive voltage Vd generated by the inductance component 16 into a first feedback voltage. The current suppression unit 17 also outputs the electromotive voltage Vd' generated in the inductor 19 magnetically coupled to the inductance component 16 to the second feedback circuit 18, and the second feedback circuit 18 converts the input electromotive voltage Vd' into a second feedback voltage. This allows the power conversion device 10 to perform synchronous feedback control based on changes in the back electromotive voltage Vd using the common inductance component 16 for the upper arm switching element 11a and the lower arm switching element 11b that are connected in series with each other.

In addition, the power conversion device 10 can reduce wiring inductance compared to a case in which the upper arm switching element 11a has an inductance component having an inductance value that generates a reverse voltage at a level that can be used for feedback control, and the lower arm switching element 11b has an inductance component having an inductance value that generates a reverse voltage at a level that can be used for feedback control. Therefore, the power conversion device 10 can achieve both reduced switching loss and reduced surge voltage or surge current compared to a case in which an inductance component is provided for each switching element 11.

(2) The power conversion device 10 can be made smaller than when it has an inductance component having an inductance value that generates a reverse voltage in the upper arm switching element 11a at a level that can be used for feedback control, and an inductance component having an inductance value that generates a reverse voltage in the lower arm switching element 11b at a level that can be used for feedback control.

The above-described embodiments may be modified as follows: The above-described embodiments and the following examples may be combined with each other as long as they are not technically inconsistent.
In the above embodiment, the inductance component 16 generates the back electromotive force Vd in response to a change in the first drain current Id1. However, the present invention is not limited to this. For example, the inductance component 16 may generate the back electromotive force Vd in response to a change in the second drain current Id2.

As shown in FIG. 3, in this case, the first connection terminal t1 of the inductance component 16 is connected to the source terminal of the lower arm switching element 11b, and the second connection terminal t2 of the inductance component 16 is connected to the negative bus LN2. The inductance component 16 generates a back electromotive voltage Vd across both connection terminals t1 and t2 due to a change in the second drain current Id2. The change in the second drain current Id2 includes a case where the second drain current Id2 starts to flow through the inductance component 16 and a case where the second drain current Id2 that had been flowing through the inductance component 16 stops. The second drain current Id2 is an example of a "second applied current."

In this case, the lower arm driver circuit 12b is connected to the first feedback circuit 15. The upper arm driver circuit 12a is connected to the second feedback circuit 18 and the current suppression unit 17. The upper arm driver circuit 12a adds the first external command voltage and the second feedback voltage, and outputs the added voltage to the upper arm switching element 11a as a gate voltage. The lower arm driver circuit 12b adds the second external command voltage and the first feedback voltage, and outputs the added voltage to the lower arm driver circuit 12b. With this configuration, the power conversion device 10 can obtain the same effects as (1) and (2).

In the above embodiment, the current suppressing unit 17 includes the inductor 19. However, the present invention is not limited to this. The current suppressing unit 17 may include a differential amplifier circuit 20.
As shown in FIG. 4, the differential amplifier circuit 20 includes a pair of input terminals. More specifically, the differential amplifier circuit 20 includes a first input terminal te1 and a second input terminal te2. The first input terminal te1 is connected to the first connection terminal t1, and the second input terminal te2 is connected to the second connection terminal t2. The differential amplifier circuit 20 includes voltage-dividing resistors 21, 22, 23, and 24, and an operational amplifier 25. The voltage-dividing resistor 21 and the voltage-dividing resistor 22 are connected in series to each other, and the voltage-dividing resistor 23 and the voltage-dividing resistor 24 are connected in series to each other. Of both ends of the voltage-dividing resistor 23, the end other than the end connected to the voltage-dividing resistor 24 is connected to the first input terminal te1. Also, of both ends of the voltage-dividing resistor 21, the end other than the end connected to the voltage-dividing resistor 22 is connected to the second input terminal te2. One of the two ends of voltage-dividing resistor 22, which is different from the end connected to voltage-dividing resistor 21, and one of the two ends of voltage-dividing resistor 24, which is different from the end connected to voltage-dividing resistor 23, are connected together, and the connection point is connected to the second input terminal td2.

The + terminal of the operational amplifier 25 is connected to the connection point between the voltage-dividing resistors 21 and 22. The - terminal of the operational amplifier 25 is connected to the connection point between the voltage-dividing resistors 23 and 24. The output terminal of the operational amplifier 25 is connected to the first input terminal td1.

With this configuration, a back electromotive voltage Vd is input to a pair of input terminals te1, te2 of the differential amplifier circuit 20, and the differential amplifier circuit 20 outputs a voltage Vd'' obtained by amplifying the potential difference between the pair of input terminals te1, te2 from the output terminal. Here, the resistance values of voltage-dividing resistors 21 and 23 match, and the resistance values of voltage-dividing resistors 22 and 24 match. In other words, the voltage-dividing ratio of voltage-dividing resistors 21 and 22 matches the voltage-dividing ratio of voltage-dividing resistors 23 and 24.

The voltage division ratio of the voltage division resistors 21 and 22, the voltage division ratio of the voltage division resistors 23 and 24, and the amplification factor of the operational amplifier 25 may be set to a voltage division ratio and amplification factor such that the voltage Vd'', which is the potential difference between the output terminal of the operational amplifier 25 and the second input terminal td2, matches the back electromotive voltage Vd, or may be set to a voltage division ratio and amplification factor such that the potential Vd'' is different from the back electromotive voltage Vd.

With this configuration, the current suppression unit 17a suppresses the first drain current Id1 from flowing into the second feedback circuit 18, and outputs a voltage (potential difference Vd'' in this embodiment) based on the back electromotive voltage Vd generated by the inductance component 16 to the second feedback circuit 18. This allows the power conversion device 10 to obtain the same effect as (1).

In the example shown in FIG. 4, the inductance component 16 may generate a back electromotive voltage Vd, for example, by a change in the second drain current Id2. In this case, the first connection terminal t1 of the inductance component 16 is connected to the source terminal of the lower arm switching element 11b, and the second connection terminal t2 of the inductance component 16 is connected to the negative bus LN2. The upper arm driver circuit 12a is connected to a current suppression unit 17a having a second feedback circuit 18 and a differential amplifier circuit 20, and the lower arm driver circuit 12b is connected to a first feedback circuit 15a. The operation of the power conversion device 10 in this configuration is the same as that of the above-mentioned embodiment and modified example, so a description thereof will be omitted.

Alternatively, the differential amplifier circuit 20 may be realized by a differential amplifier circuit 20a that detects the back electromotive voltage Vd with higher accuracy. As shown in Fig. 5, the differential amplifier circuit 20a includes voltage dividing resistors 21, 22, 23, 24, 28, and 29, and operational amplifiers 26, 27, and 30. The connections of the voltage dividing resistors 21, 22, 23, and 24 are the same as those in Fig. 4 described above, and therefore will not be described here.

The + terminal of the operational amplifier 27 is connected to the connection point between the voltage-dividing resistors 21 and 22. The - terminal of the operational amplifier 27 is connected to the output terminal of the operational amplifier 27. The + terminal of the operational amplifier 26 is connected to the connection point between the voltage-dividing resistors 23 and 24. The - terminal of the operational amplifier 26 is connected to the output terminal of the operational amplifier 26. As a result, the operational amplifiers 26 and 27 operate as a voltage follower circuit.

The output terminal of the operational amplifier 26 is connected to the negative terminal of the operational amplifier 30, and the output terminal of the operational amplifier 27 is connected to one end of the voltage-dividing resistor 28. The other end of the voltage-dividing resistor 28 is connected to one end of the voltage-dividing resistor 29. The other end of the voltage-dividing resistor 29 is connected to the second input terminal td2. In other words, the voltage-dividing resistor 28 and the voltage-dividing resistor 29 are connected in series with each other between the output terminal of the operational amplifier 27 and the second input terminal td2. The connection point between the voltage-dividing resistor 28 and the voltage-dividing resistor 29 is connected to the positive terminal of the operational amplifier 30. The output terminal of the operational amplifier 30 is connected to the first input terminal td1.

With this configuration, a back electromotive voltage Vd is input to a pair of input terminals te1 and te2 of the differential amplifier circuit 20a, and the differential amplifier circuit 20a outputs a voltage Vd', which is an amplified potential difference between the pair of input terminals te1 and te2, from the output terminal.

The voltage division ratio of the voltage division resistors 21 and 22, the voltage division ratio of the voltage division resistors 23 and 24, the voltage division ratio of the voltage division resistors 28 and 29, and the amplification factor of the operational amplifier 30 may be set to a voltage division ratio and amplification factor such that the voltage Vd', which is the potential difference between the output terminal of the operational amplifier 30 and the second input terminal td2, matches the back electromotive voltage Vd, or may be set to a voltage division ratio and amplification factor such that the voltage Vd' is different from the back electromotive voltage Vd.

As described above, the operational amplifiers 26 and 27 operate as voltage follower circuits. Therefore, the input bias voltage does not flow to the input terminals of the operational amplifiers 26, 27, and 30. Therefore, the voltage input to the input terminals of the operational amplifiers 26, 27, and 30 does not experience an offset voltage drop due to the input bias current. Therefore, the differential amplifier circuit 20a can detect the back electromotive force Vd with higher accuracy than the differential amplifier circuit 20.

With this configuration, the differential amplifier circuit 20a can transmit the back electromotive force Vd to the operational amplifier 30 with greater precision. This allows the power conversion device 10 to achieve the same effect as (1).

In the example shown in FIG. 5, the inductance component 16 may generate a back electromotive voltage Vd, for example, by a change in the second drain current Id2. In this case, the first connection terminal t1 of the inductance component 16 is connected to the source terminal of the lower arm switching element 11b, and the second connection terminal t2 of the inductance component 16 is connected to the negative bus LN2. The upper arm driver circuit 12a is connected to a current suppression unit 17b having a second feedback circuit 18 and a differential amplifier circuit 20a, and the lower arm driver circuit 12b is connected to a first feedback circuit 15a. The operation of the power conversion device 10 in this configuration is the same as that of the above-mentioned embodiment and modified example, so a description thereof will be omitted.

○The switching element 11 is not limited to a MOSFET and may be any type, for example an IGBT. In this case, the gate terminal of the switching element 11 corresponds to the "control terminal." Also, the collector current flowing between the collector and emitter of the upper arm switching element 11a corresponds to the "first applied current." Also, the collector current flowing between the collector and emitter of the lower arm switching element 11b corresponds to the "second applied current."

〇 When an inductance component 16 is provided between the upper arm switching element 11a and the lower arm switching element 11b, that is, when the first drain current Id1 flowing through the upper arm switching element 11a flows through the inductance component 16, the intermediate wiring LC3 may be connected between both ends of the inductance component 16. In particular, when the inductance component 16 is an inductor having a first connection terminal t1 and a second connection terminal t2 as in the above embodiment, the intermediate wiring LC3 is connected between the first connection terminal t1 and the second connection terminal t2. Also, when the inductance component 16 is a parasitic inductance, the intermediate wiring LC3 is connected between the first end of the intermediate wiring LC1 connected to the upper arm switching element 11a and the second end of the intermediate wiring LC2 connected to the lower arm switching element 11b.

The intermediate wiring LC needs to be connected to one of the three-phase coils 202u, 202v, and 202w, so the upper arm switching element 11a and the lower arm switching element 11b need to be arranged sufficiently apart. Therefore, the length of the intermediate wiring LC provided between the upper arm switching element 11a and the lower arm switching element 11b also becomes long. Therefore, by connecting the intermediate wiring LC that is connected to one of the three-phase coils 202u, 202v, and 202w between both ends of the inductance component 16, it is possible to prevent the intermediate wiring LC provided between the upper arm switching element 11a and the lower arm switching element 11b from becoming long.

The inductor 19 may generate an electromotive voltage Vd' of opposite polarity to the back electromotive voltage Vd. In this case, the second feedback circuit 18 inverts and amplifies the electromotive voltage Vd' and outputs it to the driver circuit 12.

The combination of the voltage dividing resistors 21, 22, 23, 24, 28, 29, the amplification factor of the operational amplifier 25, and the amplification factor of the operational amplifier 30 may be an amplification factor that takes into account the conversion loss and the voltage drops of the driver circuit 12, the second feedback circuit 18, and the operational amplifiers 25, 26, 27, 30. In more detail, the combination of the voltage dividing resistors 21, 22, 23, 24, 28, 29, the amplification factor of the operational amplifier 25, and the amplification factor of the operational amplifier 30 may be an amplification factor that amplifies the back electromotive force Vd' so that the voltage drops of the driver circuit 12, the second feedback circuit 18, and the operational amplifiers 25, 26, 27, 30 are restored.

Although each switching element 11 constitutes an inverter, this is not limited to this and may be any other type, such as a DC/DC converter that converts the DC power of the 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, 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.

The load is not limited to the electric motor 201 and may be any load.
The power conversion device 10 may be mounted on a device other than the vehicle 200. That is, the power conversion device 10 may drive a load other than the load provided on the vehicle 200.

The inductance component 16 may be realized by the parasitic inductance of the wiring on which the inductance component 16 is provided. In this case, the inductance component 16 does not have a connection terminal. With this configuration, the power conversion device 10 can be made smaller by using the parasitic inductance compared to a case in which a separate inductance is provided.

The first feedback circuit 15 and the second feedback circuit 18 may have the same configuration or different configurations.

10...power conversion device, 15, 15a, 15u, 15v, 15w...first feedback circuit, 16, 16u, 16v, 16w...inductance component, 17, 17a, 17b, 17u, 17v, 17w...current suppression section, 18, 18u, 18v, 18w...second feedback circuit, 19, 19u, 19v, 19w...inductor, 20, 20a...differential amplifier circuit, Vd...back electromotive force.

Claims (4)

a first switching element through which a first applied current flows;
a second switching element connected in series with the first switching element and through which a second applied current flows;
an inductance component that generates a back electromotive voltage in response to a change in the first applied current or a change in the second applied current;
a first feedback circuit that converts the back electromotive voltage into a first feedback voltage;
a second feedback circuit that converts the input voltage into a second feedback voltage;
a current suppression unit that suppresses the first applied current and the second applied current from flowing into the second feedback circuit and outputs a voltage based on the back electromotive voltage to the second feedback circuit;
a first driver circuit that drives the first switching element based on a first external command voltage;
a second driver circuit that drives the second switching element based on a second external command voltage;
when the inductance component generates the back electromotive voltage due to a change in the first applied current, the first driver circuit adds the first external command voltage and the first feedback voltage and outputs the added voltage to the first switching element, and the second driver circuit adds the second external command voltage and the second feedback voltage and outputs the added voltage to the second switching element,
When the inductance component generates the back electromotive voltage due to a change in the second applied current, the first driver circuit adds the first external command voltage and the second feedback voltage and outputs the added voltage to the first switching element, and the second driver circuit adds the second external command voltage and the first feedback voltage and outputs the added voltage to the second switching element.
Power conversion equipment. the inductance component is realized by a parasitic inductance of a wiring connected to the first switching element and/or the second switching element;
The power conversion device according to claim 1 . the current suppression unit includes an inductor magnetically coupled to the inductance component,
The inductor generates an electromotive voltage by the counter electromotive voltage generated by the inductance component,
The second feedback circuit converts the electromotive voltage generated by the inductor into the second feedback voltage.
The power conversion device according to claim 1 or 2. the current suppression unit includes a differential amplifier circuit,
the differential amplifier circuit receives the back electromotive voltage at a pair of input terminals, amplifies a potential difference between the pair of input terminals, and outputs the amplified potential difference;
The second feedback circuit converts the voltage output by the differential amplifier circuit into the second feedback voltage.
The power conversion device according to claim 1 or 2.

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