Power conversion device

Abstract

To suppress power loss when driving an open-winding motor in a Y-connection configuration.SOLUTION: First semiconductor switching elements are used to configure three switching elements of an upper arm and three switching elements of a lower arm of the first inverter, three switching elements of an upper arm of a second inverter, and a line-connection switching element. Second semiconductor switching elements different from the first semiconductor switching elements are used to configure three switching elements of the lower arm of the second inverter. Semiconductor switching elements with superior conduction characteristics compared to the second semiconductor switching elements are used as the first semiconductor switching elements.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power conversion device, and more particularly to a power conversion device having two inverters that drives an open winding motor. [Background technology]

[0002] A conventional power conversion device of this type includes a first inverter connected to a power line connected to a battery and connected to each phase of an open-winding motor, a second inverter connected to the power line and connected to each phase of the open-winding motor, and two switches attached to the positive and negative sides of the power line between the first and second inverters (see, for example, Patent Document 1). This power conversion device switches between Y-connection drive, which performs Y control when the two switches are open, and Δ-connection drive, which performs Δ control when the two switches are closed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-014829 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned power conversion device, when the Y-connection is driven, the switch or the upper arm or lower arm of the second inverter is always on, which causes inconveniences such as power loss due to current resistance of the switching elements that are always on and overheating of the switching elements.

[0005] The main object of the power conversion device of the present disclosure is to suppress power loss when driving an open winding motor with a Y connection. [Means for solving the problem]

[0006] The power conversion device of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The power conversion device of the present disclosure includes: A power conversion device connected to a power storage device and a three-phase open winding motor, a first inverter connected to a power line connected to the power storage device and connected to each phase of the open winding motor; a second inverter connected to the power line and to each phase of the open winding motor; a line connection switching element attached to a positive side line of the power line between the first inverter and the second inverter; Equipped with the three switching elements of the upper arm and the three switching elements of the lower arm of the first inverter, the three switching elements of the upper arm of the second inverter, and the line connection switching elements are configured as first semiconductor switching elements; Three switching elements of a lower arm of the second inverter are configured by second semiconductor switching elements different from the first semiconductor switching elements, The first semiconductor switching element is a semiconductor switching element having a superior conduction characteristic to the second semiconductor switching element. It is characterized by:

[0008] The power conversion device of the present disclosure includes a first inverter connected to a power line connected to a power storage device and connected to each phase of an open-winding motor, a second inverter connected to the power line and connected to each phase of the open-winding motor, and a line-connecting switching element attached to a positive-side line of the power line between the first inverter and the second inverter.The three switching elements of the upper arm and the three switching elements of the lower arm of the first inverter and the three switching elements of the upper arm and the line-connecting switching element are configured with first semiconductor switching elements, and the three switching elements of the lower arm of the second inverter are configured with second semiconductor switching elements different from the first semiconductor switching elements, and the first semiconductor switching elements are semiconductor switching elements having superior conduction characteristics to the second semiconductor switching elements. As a result, when an open winding motor is driven in a Y-connection by controlling the switching elements of the first inverter while keeping the line connection switching element off and the three switching elements of the upper arm of the second inverter on and the three switching elements of the lower arm of the second inverter off, by using first semiconductor switching elements having excellent conduction characteristics as the three switching elements of the upper arm of the second inverter, power loss can be suppressed compared to using second semiconductor switching elements as the three switching elements of the upper arm of the second inverter. Also, when an open winding motor is driven in a Δ-connection by controlling the switching elements of the first inverter and the switching elements of the second inverter while keeping the line connection switching element on, by using the first semiconductor switching elements having excellent conduction characteristics as the line connection switching elements, power loss can be suppressed compared to using the second semiconductor switching elements as the line connection switching elements.In addition, since the second semiconductor switching elements are generally cheaper than the first semiconductor switching elements, which have excellent conduction characteristics, by constructing the three switching elements of the lower arm of the second inverter from the second semiconductor switching elements, the power conversion device can be made cheaper than one in which the three switching elements of the lower arm of the second inverter are also constructed from the first semiconductor switching elements.

[0009] In addition, the power conversion device of the present disclosure is A power conversion device connected to a power storage device and a three-phase open winding motor, a first inverter connected to a power line connected to the power storage device and connected to each phase of the open winding motor; a second inverter connected to the power line and to each phase of the open winding motor; a line connection switching element attached to a negative side line of the power line between the first inverter and the second inverter; Equipped with the three switching elements of the upper arm and the three switching elements of the lower arm of the first inverter, the three switching elements of the lower arm of the second inverter, and the line connection switching elements are configured as first semiconductor switching elements; Three switching elements of an upper arm of the second inverter are configured by second semiconductor switching elements different from the first semiconductor switching elements, The first semiconductor switching element is a semiconductor switching element having a superior conduction characteristic to the second semiconductor switching element. It is characterized by:

[0010] The power conversion device of the present disclosure includes a first inverter connected to a power line connected to a power storage device and connected to each phase of an open-winding motor, a second inverter connected to the power line and connected to each phase of the open-winding motor, and a line-connecting switching element attached to a positive-side line of the power line between the first inverter and the second inverter.The three switching elements of the upper arm and the three switching elements of the lower arm of the first inverter and the three switching elements of the lower arm of the second inverter are configured with first semiconductor switching elements, the three switching elements of the upper arm of the second inverter are configured with second semiconductor switching elements different from the first semiconductor switching elements, and the first semiconductor switching elements are semiconductor switching elements having superior conduction characteristics to the second semiconductor switching elements. As a result, when the open winding motor is driven in a Y-connection by controlling the switching elements of the first inverter while the line connection switching element is turned off and the three switching elements of the lower arm of the second inverter are turned on and the three switching elements of the upper arm of the second inverter are turned off, by using the first semiconductor switching elements having excellent conduction characteristics as the three switching elements of the lower arm of the second inverter, power loss can be suppressed compared to using the second semiconductor switching elements as the three switching elements of the lower arm of the second inverter. Also, when the open winding motor is driven in a Δ-connection by controlling the switching elements of the first inverter and the switching elements of the second inverter while the line connection switching element is turned on, by using the first semiconductor switching elements having excellent conduction characteristics as the line connection switching elements, power loss can be suppressed compared to using the second semiconductor switching elements as the line connection switching elements.Even in this case, since the second semiconductor switching elements are generally cheaper than the first semiconductor switching elements, which have superior conduction characteristics, by forming the three switching elements of the lower arm of the second inverter from the second semiconductor switching elements, the power conversion device can be made less expensive than a power conversion device in which the three switching elements of the lower arm of the second inverter are also formed from the first semiconductor switching elements.

[0011] In the power conversion device of the present disclosure, the first semiconductor switching element may be a switching element made of a wide band gap semiconductor using gallium nitride (GaN) or silicon carbide (SiC), and the second semiconductor switching element may be a switching element made of a semiconductor using silicon (Si). In this case, the first semiconductor switching element may be a SiC-MOSFET (SiC-Metal Oxide Semiconductor Field Effect Transistor), and the second semiconductor switching element may be a Si-IGBT (Si-Insulated Gate Bipolar Transistor). [Brief description of the drawings]

[0012] [Figure 1] 1 is a configuration diagram showing an outline of the configuration of a drive device 20 including a power conversion device 30 according to an embodiment of the present disclosure. [Diagram 2] 2 is an explanatory diagram showing an example of the on / off states of switching elements and current flows when an open winding motor 40 is Y-connection driven by a power conversion device 30. FIG. [Diagram 3] FIG. 13 is a configuration diagram showing an outline of the configuration of a drive device 20B including a power conversion device 30B of a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of a drive device 20 including a power conversion device 30 as one embodiment of the present disclosure. The drive device 20 includes a battery 22, the power conversion device 30, and an open winding motor 40.

[0014] The battery 22 is configured as, for example, a lithium ion secondary battery or a nickel-hydrogen secondary battery, and has a positive terminal and a negative terminal connected to a positive power line 24p and a negative power line 24n. A smoothing capacitor 26 is attached to the positive power line 24p and the negative power line 24n.

[0015] The power conversion device 30 includes a first inverter 32, a second inverter 34, and a connection switch 36.

[0016] The first inverter 32 is connected to the positive power line 24p and the negative power line 24n to which the battery 22 is connected, and includes six transistors T11 to T16 as switching elements and six diodes D11 to D16 connected in parallel to the six transistors T11 to T16, respectively. The transistors T11 to T16 are all configured with SiC-MOSFETs (SiC-Metal Oxide Semiconductor Field Effect Transistors). Among the transistors T11 to T16, pairs of two transistors (transistors T11 and T14, transistors T12 and T15, and transistors T13 and T16) are arranged so as to be on the source side and sink side with respect to the positive power line 24p and the negative power line 24n. In addition, each of the connection points of the pair of transistors T11 to T16 is connected to one end side of the three-phase coils (u-phase, v-phase, and w-phase coils) of the open-winding motor 40.

[0017] The second inverter 34 is connected to the positive power line 24p and the negative power line 24n to which the battery 22 is connected, so as to sandwich the first inverter 32 by the battery 22, and has six transistors T21 to T26 as switching elements, and six diodes D21 to D26 connected in parallel to each of the six transistors T21 to T26. The transistors T21 to T23 constituting the upper arm of the second inverter 34 are composed of SiC-MOSFETs like the transistors T11 to T16 of the first inverter 32, and the transistors T24 to T26 constituting the lower arm of the second inverter 34 are composed of Si-IGBTs (Si-insulated gate bipolar transistors). The transistors T21 to T26 are paired in pairs (transistors T21 and T24, transistors T22 and T25, transistors T23 and T26) and are arranged so as to be the source side and the sink side with respect to the positive power line 24p and the negative power line 24n. The connection points of two pairs of transistors T21 to T26 are connected to the other ends of the three-phase coils (u-phase, v-phase, and w-phase coils) of the open winding motor 40, respectively.

[0018] The connection switch 36 is attached to the positive power line 24p between the first inverter 32 and the second inverter 34. The connection switch 36 is made of a SiC-MOSFET, like the transistors T11 to T16 of the first inverter 32 and the transistors T21 to T23 that form the upper arm of the second inverter 34.

[0019] The open winding motor 40 is a generator motor in which both ends of each of the three-phase windings (u-phase, v-phase, and w-phase) are configured as connection terminals, and three connection points of two paired transistors of the first inverter 32 are connected to one end of each of the three-phase windings (u-phase, v-phase, and w-phase), and three connection points of two paired transistors of the second inverter 34 are connected to the other end of each of the three-phase windings (u-phase, v-phase, and w-phase).

[0020] In the power conversion device 30 of the embodiment, the open winding motor 40 can be driven in a Y-connection by controlling the switching of the transistors T11 to T16 of the first inverter 32 while the connection switch 36 is turned off, the transistors T21 to T23 of the upper arm of the second inverter 34 are turned on, and the transistors T24 to T26 of the lower arm are turned off. That is, by turning off the connection switch 36 and turning on the transistors T21 to T23 of the upper arm of the second inverter 34, the u-phase, v-phase, and w-phase of the open winding motor 40 are set as a neutral point by the turned-on transistors T21 to T23, and the open winding motor 40 is driven by the first inverter 32 as a Y-connection type motor. As an example of driving the open winding motor 40 as a Y-connection type motor by the first inverter 32, the state of the current flowing through the drive device 20 when the transistors T11 and T16 are turned on and the transistors T12, T13, T14, and T15 are turned off is shown in FIG. 2. In Fig. 2, the current flow is indicated by thick solid arrows. During this Y-connection drive, the transistors T21 to T23 of the upper arm of the second inverter 34 are always on, but because the transistors T21 to T23 are made of SiC-MOSFETs, which have superior conduction characteristics compared to Si-IGBTs, power loss during Y-connection drive can be suppressed compared to when the transistors T21 to T23 are made of Si-IGBTs.

[0021] In the power conversion device 30 of the embodiment, the open winding motor 40 can be driven in a Δ connection by controlling the switching of the transistors T11 to T16 of the first inverter 32 and the switching of the transistors T21 to T26 of the second inverter 34 while the connection switch 36 is on. At this time, the connection switch 36 is always in an on state, but because the connection switch 36 is made of a SiC-MOSFET with excellent conduction characteristics, power loss during Δ connection driving can be suppressed.

[0022] In the power conversion device 30 of the embodiment described above, the six transistors T11-T16 of the first inverter 32, the connection switch 36, and the transistors T21-T23 constituting the upper arm of the second inverter 34 are made of SiC-MOSFETs with excellent conduction characteristics, thereby making it possible to suppress power loss during Y-connection driving and power loss during Δ-connection driving. Furthermore, since Si-IGBTs and SiC-MOSFETs are generally inexpensive, the power conversion device 30 can be made less expensive than one in which the transistors T24-T26 constituting the lower arm of the second inverter 34 are made of SiC-MOSFETs.

[0023] In the power converter 30 of the embodiment, the six transistors T11-T16 of the first inverter 32, the connection switch 36 attached to the positive power line 24p, and the transistors T21-T23 constituting the upper arm of the second inverter 34 are made of SiC-MOSFETs with excellent conduction characteristics, and the transistors T24-T26 constituting the lower arm of the second inverter 34 are made of Si-IGBTs with poorer conduction characteristics than SiC-MOSFETs. However, as shown in the power converter 30B of the drive device 20B of the modified example of FIG. 3, the six transistors T11-T16 of the first inverter 32, the connection switch 36B attached to the negative power line 24n, and the transistors T34-T36 constituting the lower arm of the second inverter 34B may be made of SiC-MOSFETs with excellent conduction characteristics, and the transistors T31-T33 constituting the upper arm of the second inverter 34B may be made of Si-IGBTs with poorer conduction characteristics than SiC-MOSFETs. In this case, the open winding motor 40 can be driven in a Y-connection by controlling the switching of the transistors T11-T16 of the first inverter 32 while the connection switch 36B is turned off and the transistors T34-T36 of the lower arm of the second inverter 34 are turned on and the transistors T31-T33 of the upper arm are turned off. Also, the open winding motor 40 can be driven in a Δ-connection by controlling the switching of the transistors T11-T16 of the first inverter 32 and the transistors T31-T36 of the second inverter 34B while the connection switch 36 is turned on. With the power conversion device 30 of this modified example, it is possible to suppress power loss during Y-connection driving and power loss during Δ-connection driving.

[0024] In the power conversion device 30 of the embodiment, the six transistors T11 to T16 of the first inverter 32, the connection switch 36, and the transistors T21 to T23 constituting the upper arm of the second inverter 34 are configured with SiC-MOSFETs having excellent conduction characteristics. However, since any semiconductor element having excellent conduction characteristics will do, the six transistors T11 to T16 of the first inverter 32, the connection switch 36, and the transistors T21 to T23 constituting the upper arm of the second inverter 34 may be configured with switching elements made of wide bandgap semiconductors, for example, switching elements made of wide bandgap semiconductors using gallium nitride (GaN).

[0025] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problems will be described below. In the embodiment, the battery 22 corresponds to the "electricity storage device", the open winding motor 40 corresponds to the "open winding motor", the first inverter 32 corresponds to the "first inverter", the second inverter 34 corresponds to the "second inverter", and the connection switch 36 corresponds to the "line connection switching element".

[0026] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the Means for Solving the Problem column.

[0027] The present disclosure has been described above using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be embodied in various forms without departing from the gist of the present disclosure. [Industrial Applicability]

[0028] The present disclosure is applicable to the power conversion device manufacturing industry and the like. [Explanation of symbols]

[0029] 20 drive device, 22 battery, 24p positive power line, 24n negative power line, 26 capacitor, 30 power conversion device, 32 first inverter, 34 second inverter, 36 connection switch, 40 open winding motor, T11 to T16, T21 to T26 transistors, D11 to D16, D21 to D26 diodes.

Claims

1. A power conversion device connected to a power storage device and a three-phase open winding motor, a first inverter connected to a power line connected to the power storage device and connected to each phase of the open winding motor; a second inverter connected to the power line and to each phase of the open winding motor; a line connection switching element attached to a positive side line of the power line between the first inverter and the second inverter; Equipped with the three switching elements of the upper arm and the three switching elements of the lower arm of the first inverter, the three switching elements of the upper arm of the second inverter, and the line connection switching elements are configured by first semiconductor switching elements; Three switching elements of a lower arm of the second inverter are configured by second semiconductor switching elements different from the first semiconductor switching elements, The first semiconductor switching element is a semiconductor switching element having a superior conduction characteristic to the second semiconductor switching element. A power conversion device comprising:

2. A power conversion device connected to a power storage device and a three-phase open winding motor, a first inverter connected to a power line connected to the power storage device and connected to each phase of the open winding motor; a second inverter connected to the power line and to each phase of the open winding motor; a line connection switching element attached to a negative side line of the power line between the first inverter and the second inverter; Equipped with the three switching elements of the upper arm and the three switching elements of the lower arm of the first inverter, the three switching elements of the lower arm of the second inverter, and the line connection switching elements are configured by first semiconductor switching elements; Three switching elements of an upper arm of the second inverter are configured by second semiconductor switching elements different from the first semiconductor switching elements, The first semiconductor switching element is a semiconductor switching element having a superior conduction characteristic to the second semiconductor switching element. A power conversion device comprising:

3. 3. The power conversion device according to claim 1, The first semiconductor switching element is a switching element made of a wide band gap semiconductor using gallium nitride (GaN) or silicon carbide (SiC), The second semiconductor switching element is a switching element made of a semiconductor using silicon (Si). Power conversion equipment.

4. 4. The power conversion device according to claim 3, the first semiconductor switching element is a SiC-MOSFET, The second semiconductor switching element is a Si-IGBT. Power conversion equipment.

Images