Power converter
The use of high-conductivity semiconductor switching elements in power conversion devices for open-winding motors reduces power loss and overheating, achieving efficient and cost-effective operation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-10-18
- Publication Date
- 2026-05-15
AI Technical Summary
Conventional power conversion devices for open-winding motors experience power loss and overheating due to the conduction resistance of always-on switching elements during Y-connection driving.
Employing semiconductor switching elements with superior conductivity characteristics, such as SiC-MOSFETs, for the upper arms of both inverters and using cheaper Si-IGBTs for the lower arms, along with a line connection switching element, to minimize power loss during Y- and Δ-connection driving.
Suppresses power loss and overheating by utilizing high-conductivity switching elements, while maintaining cost-effectiveness by incorporating less expensive elements where possible.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a power conversion device, and more particularly to a power conversion device having two inverters for driving an open-winding motor.
Background Art
[0002] Conventionally, as this type of power conversion device, there has been proposed one including 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 inverter and the second inverter (see, for example, Patent Document 1). This power conversion device switches between Y-connection driving in which Y control is performed with the two switches in an open state and Δ-connection driving in which Δ control is performed with the two switches in a closed state.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, in the above-described power conversion device, during Y-connection driving, since the switches and the upper or lower arm of the second inverter are always in an on state, there are disadvantages such as power loss due to the conduction resistance of the always-on switching element and overheating of the switching element.
[0005] The main object of the power conversion device of the present disclosure is to suppress power loss when driving an open-winding motor in Y-connection.
Means for Solving the Problems
[0006] The power conversion device of this disclosure employs the following means to achieve the main objective described above.
[0007] The power conversion device of this disclosure, A power conversion device connected to an energy storage device and a three-phase open-wound motor, A first inverter is connected to the power line connected to the energy storage device and to each phase of the open-winding motor, A second inverter is connected to the aforementioned power line and to each phase of the open-winding motor, A line connection switching element attached to the positive terminal side line of the power line between the first inverter and the second inverter, Equipped with, The three switching elements on the upper arm and the three switching elements on the lower arm of the first inverter, the three switching elements on the upper arm of the second inverter, and the line connection switching element are all composed of first semiconductor switching elements. The three switching elements of the lower arm of the second inverter are composed of second semiconductor switching elements that are different from the first semiconductor switching elements. As the first semiconductor switching element, a semiconductor switching element having superior conductivity characteristics compared to the second semiconductor switching element is used. It is characterized by the following:
[0008] The power conversion device of this disclosure comprises a first inverter connected to a power line connected to an energy storage device and connected to each phase of an open-winding motor, a second inverter connected to a power line and connected to each phase of an open-winding motor, and a line connection switching element attached to the positive electrode side line of the power line between the first inverter and the second inverter. The three switching elements on the upper arm and the three switching elements on the lower arm of the first inverter, the three switching elements on the upper arm of the second inverter, and the line connection switching element are made of first semiconductor switching elements, the three switching elements on the lower arm of the second inverter are made of second semiconductor switching elements different from the first semiconductor switching elements, and a semiconductor switching element with superior conductivity characteristics compared to the second semiconductor switching element is used as the first semiconductor switching element. As a result, when driving an open-winding motor in a Y-connection by switching control of each switching element of the first inverter with the line connection switching element turned off, the three switching elements on the upper arm of the second inverter turned on, and the three switching elements on the lower arm of the second inverter turned off, using the first semiconductor switching element with excellent conductivity as the three switching elements of the upper arm of the second inverter can suppress power loss compared to using the second semiconductor switching element as the three switching elements of the upper arm of the second inverter. Furthermore, when driving an open-winding motor in a Δ-connection by switching control of each switching element of the first inverter with the line connection switching element turned on, and switching control of each switching element of the second inverter, using the first semiconductor switching element with excellent conductivity as the line connection switching element can suppress power loss compared to using the second semiconductor switching element as the line connection switching element.Furthermore, since the second semiconductor switching element is generally cheaper than the first semiconductor switching element, which has superior conductivity characteristics, by using the second semiconductor switching element for the three switching elements in the lower arm of the second inverter, the power conversion device can be made cheaper compared to one in which the three switching elements in the lower arm of the second inverter are also made of the first semiconductor switching element.
[0009] Furthermore, the power conversion device of this disclosure is A power conversion device connected to an energy storage device and a three-phase open-wound motor, A first inverter is connected to the power line connected to the energy storage device and to each phase of the open-winding motor, A second inverter is connected to the aforementioned power line and to each phase of the open-winding motor, A line connection switching element attached to the negative electrode line of the power line between the first inverter and the second inverter, Equipped with, The three switching elements on the upper arm and the three switching elements on the lower arm of the first inverter, the three switching elements on the lower arm of the second inverter, and the line connection switching element are all composed of first semiconductor switching elements. The three switching elements of the upper arm of the second inverter are composed of second semiconductor switching elements that are different from the first semiconductor switching elements. As the first semiconductor switching element, a semiconductor switching element having superior conductivity characteristics compared to the second semiconductor switching element is used. It is characterized by the following:
[0010] Furthermore, the power conversion device of this disclosure includes a first inverter connected to a power line connected to an energy storage device and connected to each phase of an open-winding motor, a second inverter connected to a power line and connected to each phase of an open-winding motor, and a line connection switching element attached to the positive electrode side line of the power line between the first inverter and the second inverter. The three switching elements on the upper arm and the three switching elements on the lower arm of the first inverter, the three switching elements on the lower arm of the second inverter, and the line connection switching element are made of first semiconductor switching elements, the three switching elements on the upper arm of the second inverter are made of second semiconductor switching elements different from the first semiconductor switching elements, and a semiconductor switching element with superior conductivity characteristics compared to the second semiconductor switching element is used as the first semiconductor switching element. As a result, when driving an open-winding motor in a Y-connection by switching control each switching element of the first inverter with the line connection switching element turned off, the three switching elements on the lower arm of the second inverter turned on, and the three switching elements on the upper arm of the second inverter turned off, using the first semiconductor switching element with excellent conductivity as the three switching elements of the lower arm of the second inverter can suppress power loss compared to using the second semiconductor switching element as the three switching elements of the lower arm of the second inverter. Furthermore, when driving an open-winding motor in a Δ-connection by switching control each switching element of the first inverter with the line connection switching element turned on, and switching control each switching element of the second inverter, using the first semiconductor switching element with excellent conductivity as the line connection switching element can suppress power loss compared to using the second semiconductor switching element as the line connection switching element.In this case as well, since the second semiconductor switching element is generally cheaper than the first semiconductor switching element which has superior conductivity characteristics, by using the second semiconductor switching element to configure the three switching elements in the lower arm of the second inverter, the power conversion device can be made cheaper compared to one in which the three switching elements in the lower arm of the second inverter are also configured using the first semiconductor switching element.
[0011] In the power conversion device of this disclosure, the first semiconductor switching element may be a switching element made of a wide-bandgap 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 explanation of the drawing]
[0012] [Figure 1] This diagram shows a schematic configuration of a drive unit 20 including a power converter 30 as one embodiment of the present disclosure. [Figure 2] This is an explanatory diagram showing an example of the on / off state of the switching element and the current flow when an open-winding motor 40 is driven in a Y-connection by a power conversion device 30. [Figure 3] This is a schematic diagram showing the configuration of the drive unit 20B, including the modified power converter 30B. [Modes for carrying out the invention]
[0013] Next, a mode (embodiment) for implementing 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 an embodiment of the present disclosure. The drive device 20 includes a battery 22, a 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-metal hydride secondary battery, and its positive and negative terminals are connected to the positive-side power line 24p and the negative-side power line 24n. A smoothing capacitor 26 is attached to the positive-side power line 24p and the negative-side 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-side power line 24p and the negative-side power line 24n to which the battery 22 is connected, and has six transistors T11 to T16 as switching elements and six diodes D11 to D16 connected in parallel to each of the six transistors T11 to T16. The transistors T11 to T16 are all composed of SiC-MOSFETs (SiC - Metal Oxide Semiconductor Field Effect Transistors). Among the transistors T11 to T16, two transistors in pairs (transistor T11 and transistor T14, transistor T12 and transistor T15, transistor T13 and transistor T16) are arranged so as to be on the source side and the sink side with respect to the positive-side power line 24p and the negative-side power line 24n. Also, each of the connection points of the two transistors that form a pair among the 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 with the battery 22, and includes 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 formed of SiC-MOSFETs, similar to 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 formed of Si-IGBT (Si - Insulated Gate Bipolar Transistor). Among the transistors T21 to T26, two transistors paired (transistor T21 and transistor T24, transistor T22 and transistor T25, transistor T23 and transistor T26) are arranged so as to be on the source side and the sink side with respect to the positive power line 24p and the negative power line 24n. Further, each connection point of the two paired transistors of the transistors T21 to T26 is connected to the other end side 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 between the first inverter 32 and the second inverter 34 on the positive power line 24p. The connection switch 36 is formed of SiC-MOSFET, similar to the transistors T11 to T16 of the first inverter 32 and the transistors T21 to T23 constituting 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 of the u-phase, v-phase, and w-phase are configured as connection terminals. At one end side of each of the three-phase windings of the u-phase, v-phase, and w-phase, three connection points of two paired transistors of the first inverter 32 are connected, and at the other end side of each of the three-phase windings of the u-phase, v-phase, and w-phase, three connection points of two paired transistors of the second inverter 34 are connected.
[0020] In the power conversion device 30 of this embodiment, the open-wound motor 40 can be driven in a Y-connection by switching control of transistors T11 to T16 of the first inverter 32 with the connection switch 36 turned off, and transistors T21 to T23 on the upper arm of the second inverter 34 turned on while transistors T24 to T26 on the lower arm turned off. That is, by turning off the connection switch 36 and turning on transistors T21 to T23 on the upper arm of the second inverter 34, the u-phase, v-phase, and w-phase of the open-wound motor 40 are neutralized by the turned-on transistors T21 to T23, and the open-wound motor 40 is driven by the first inverter 32 as a Y-connection type motor. As an example when the open-wound motor 40 is driven by the first inverter 32 as a Y-connection type motor, Figure 2 shows the current flowing through the drive device 20 when transistors T11 and T16 are on and transistors T12, T13, T14, and T15 are off. Figure 2 shows the flow of current indicated by the thick solid arrows. In this Y-connection drive, transistors T21 to T23 on the upper arm of the second inverter 34 are always on. However, since transistors T21 to T23 are made of SiC-MOSFETs, which have superior conductivity characteristics compared to Si-IGBTs, power loss during Y-connection drive can be suppressed compared to a configuration in which transistors T21 to T23 are made of Si-IGBTs.
[0021] In the power conversion device 30 of this embodiment, the open-wound motor 40 can be driven in a delta connection by switching control of transistors T11 to T16 of the first inverter 32 and transistors T21 to T26 of the second inverter 34 while the connection switch 36 is turned ON. At this time, the connection switch 36 is always ON, but since the connection switch 36 is made of a SiC-MOSFET with excellent conductivity characteristics, power loss during delta connection driving can be suppressed.
[0022] In the power converter 30 of the embodiment described above, the six transistors T11 to T16 of the first inverter 32, the connecting switch 36, and the transistors T21 to T23 that constitute the upper arm of the second inverter 34 are made of SiC-MOSFETs with excellent conductivity characteristics, thereby suppressing 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 converter 30 can be made less expensive compared to one in which the transistors T24 to T26 that constitute 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 to T16 of the first inverter 32, the connecting switch 36 attached to the positive-side power line 24p, and the transistors T21 to T23 constituting the upper arm of the second inverter 34 are made of SiC-MOSFETs with excellent conductivity, while the transistors T24 to T26 constituting the lower arm of the second inverter 34 are made of Si-IGBTs, which have inferior conductivity compared to SiC-MOSFETs. However, as shown in the power converter 30B of the modified drive device 20B in Figure 3, the six transistors T11 to T16 of the first inverter 32, the connecting switch 36B attached to the negative-side power line 24n, and the transistors T34 to T36 constituting the lower arm of the second inverter 34B may be made of SiC-MOSFETs with excellent conductivity, while the transistors T31 to T33 constituting the upper arm of the second inverter 34B may be made of Si-IGBTs, which have inferior conductivity compared to SiC-MOSFETs. In this case, the open-wound motor 40 can be driven in a Y-connection by switching control of transistors T11 to T16 of the first inverter 32 while the connection switch 36B is turned off, and transistors T34 to T36 of the lower arm of the second inverter 34 are turned on and transistors T31 to T33 of the upper arm are turned off. Alternatively, the open-wound motor 40 can be driven in a delta-connection by switching control of transistors T11 to T16 of the first inverter 32 and transistors T31 to T36 of the second inverter 34B while the connection switch 36 is turned on. This modified power converter 30 can also suppress power loss during Y-connection driving and power loss during delta-connection driving.
[0024] In the power conversion device 30 of this embodiment, the six transistors T11 to T16 of the first inverter 32, the connecting switch 36, and the transistors T21 to T23 that constitute the upper arm of the second inverter 34 are made of SiC-MOSFETs with excellent conductivity. However, any semiconductor element with excellent conductivity is acceptable, so the six transistors T11 to T16 of the first inverter 32, the connecting switch 36, and the transistors T21 to T23 that constitute the upper arm of the second inverter 34 may be made of wide-bandgap semiconductor switching elements, for example, wide-bandgap semiconductor switching elements 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 problem will be explained. In the embodiment, the battery 22 corresponds to the "energy 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 connecting switch 36 corresponds to the "line connection switching element".
[0026] Furthermore, 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 problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.
[0027] Although the present disclosure has been described above using embodiments, the present disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of the present disclosure. [Industrial applicability]
[0028] This disclosure can be used in industries such as the manufacturing of power conversion equipment. [Explanation of Symbols]
[0029] 20 Drive unit, 22 Battery, 24p Positive power line, 24n Negative power line, 26 Capacitor, 30 Power converter, 32 First inverter, 34 Second inverter, 36 Connection switch, 40 Open-wound motor, T11~T16, T21~T26 Transistors, D11~D16, D21~D26 Diodes.
Claims
1. A power conversion device connected to an energy storage device and a three-phase open-wound motor, A first inverter is connected to the power line connected to the energy storage device and to each phase of the open-winding motor, A second inverter connected to the aforementioned power line and connected to each phase of the open-winding motor, A line connection switching element attached to the positive terminal side line of the power line between the first inverter and the second inverter, Equipped with, The three switching elements on the upper arm and the three switching elements on the lower arm of the first inverter, the three switching elements on the upper arm of the second inverter, and the line connection switching element are all composed of first semiconductor switching elements. The three switching elements of the lower arm of the second inverter are composed of second semiconductor switching elements that are different from the first semiconductor switching elements. As the first semiconductor switching element, a semiconductor switching element having superior conductivity characteristics compared to the second semiconductor switching element is used. A power conversion device characterized by the following features.
2. A power conversion device connected to an energy storage device and a three-phase open-wound motor, A first inverter is connected to the power line connected to the energy storage device and to each phase of the open-winding motor, A second inverter connected to the aforementioned power line and connected to each phase of the open-winding motor, A line connection switching element attached to the negative electrode side line of the power line between the first inverter and the second inverter, Equipped with, The three switching elements on the upper arm and the three switching elements on the lower arm of the first inverter, the three switching elements on the lower arm of the second inverter, and the line connection switching element are all composed of first semiconductor switching elements. The three switching elements of the upper arm of the second inverter are composed of second semiconductor switching elements that are different from the first semiconductor switching elements. As the first semiconductor switching element, a semiconductor switching element having superior conductivity characteristics compared to the second semiconductor switching element is used. A power conversion device characterized by the following features.
3. A power conversion device according to claim 1 or 2, The first semiconductor switching element is a switching element made of a wide-bandgap 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 converter.
4. A power conversion device according to claim 3, The aforementioned first semiconductor switching element is a SiC-MOSFET, The second semiconductor switching element is a Si-IGBT. Power converter.