Power converter

Abstract

To provide a power converter that can drive a motor with a coil of an open-end structure while stably controlling the secondary-side voltage of a GND-sharing dual inverter.SOLUTION: An primary-side inverter is connected to a DC power source, a secondary-side inverter is connected to a capacitor, and the negative power source lines of the primary-side inverter and the secondary-side inverter are shared. The power converter includes a controller 6 which controls a secondary-side voltage Vdc2, which is the charge voltage of the capacitor. The controller 6 has a secondary-side voltage control unit 23 for generating a zero-phase voltage command value vzref for flowing a zero-phase current iz necessary to control a secondary-side voltage Vdc2 to a secondary-side voltage instruction value Vdc2ref.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power conversion device that applies an AC output to a motor having a winding with an open-end structure that is open at both ends, using two inverters, a primary-side inverter and a secondary-side inverter.

Background Art

[0002] For example, when driving an electric compressor used in an air conditioner of an electric vehicle such as an electric vehicle or a hybrid vehicle, a three-phase permanent magnet synchronous motor is used. However, in an existing motor control method using an inverter, as shown in FIG. 7, d-axis current i d and q-axis current i q vector control for controlling is common.

[0003] By modeling a controller and a control target (plant model) as shown in FIG. 7, the design of the controller becomes possible. That is, it is important that the control target is modeled in order to design the controller.

[0004] On the other hand, in a motor driven by an inverter, when the input voltage decreases, the drivable rotational speed decreases, or the outputable torque decreases at a high rotational speed, so the drivable range at high speed tends to narrow. In the above-described in-vehicle electric compressor that drives a compression mechanism with a motor housed in a housing, the required range of the input voltage has not been wide conventionally, but in recent years, the requirement for the drivable region with respect to changes in the input voltage has become stricter even for electric compressors.

[0005] However, in an in-vehicle electric compressor, since the battery of the electric vehicle is used as a DC power source, the input voltage may decrease. When the input voltage decreases, the outputable torque becomes low in the region where the rotational speed is high.

[0006] Therefore, as a method of increasing the output voltage to the motor with respect to the input voltage, a so-called open-end winding structure motor having a plurality of stator windings with both ends open (a motor with the neutral point of the motor taken out to the outside without connection) is sandwiched between two inverters on the primary side and the secondary side, and a dual inverter type power conversion device that applies the differential voltage between the primary side inverter and the secondary side inverter to the motor for driving has been variously proposed (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In a dual inverter type power conversion device for driving a motor having an open-end winding structure, since there are two inverters on the primary side and the secondary side, there is a degree of freedom in how to distribute the voltage command value to the two inverters.

[0009] And the conventional dual inverter type power conversion devices are roughly classified into three types shown in FIGS. 8 to 10. FIG. 8 is a power conversion device of a general power supply common type dual inverter. In FIG. 8, M is a motor having the winding of the above open-end structure, INV1 is a primary side inverter, and INV2 is a secondary side inverter, and the stator winding of the motor M is sandwiched between these.

[0010] The power - common - type dual inverter is the simplest method, which makes the power supplies on the primary side and the secondary side common. Since there is only one power supply, the breakdown voltages of all the semiconductor devices and passive devices (such as capacitors) on the primary side and the secondary side need to be set according to the power - supply voltage. Also, since there is a path through which zero - phase current flows, it is necessary to take measures against zero - phase current. However, both the primary side and the secondary side can output active power and reactive power.

[0011] In addition, in the case of this method, since a common power supply is used on the primary side and the secondary side, 1 / 2 of the voltage command value will be output by each of the inverters INV1 and INV2.

[0012] Next, Fig. 9 shows a power - conversion device of an isolated - power - type dual inverter. Also in Fig. 9, M is a motor equipped with a winding of open - end structure, INV1 is a primary - side inverter, and INV2 is a secondary - side inverter. These sandwich the stator winding of the motor M. In the case of this method, two isolated power supplies are arranged on the primary side and the secondary side respectively. Since it is necessary to prepare two isolated power supplies, there is a concern about increased size. However, there are advantages that zero - phase current does not flow and both the primary side and the secondary side can output active power and reactive power.

[0013] In addition, in the case of this method, since the primary side and the secondary side are driven by separate power supplies (voltages), the output will be according to the ratio of the voltages. For example, if the voltage V dc1 of the power supply on the primary side is 1 / 2 of the voltage V dc2 of the power supply on the secondary side, the primary - side inverter INV1 will output 1 / 3 of the voltage command value and the secondary - side inverter INV2 will output 2 / 3 of the voltage command value.

[0014] Next, FIG. 10 shows a power conversion device of a floating capacitor type dual inverter. Also in FIG. 10, M is a motor having a winding with an open end structure, INV1 is a primary side inverter, and INV2 is a secondary side inverter. The stator winding of the motor M is sandwiched between these. In this method, a floating capacitor C is arranged in the secondary side inverter, and the secondary side voltage is controlled by charging and discharging the capacitor from the motor side.

[0015] The floating capacitor method has the characteristics that the secondary side voltage can be controlled and zero-phase current does not flow. On the other hand, in order to drive the switching element of the secondary side inverter, it is necessary to separately prepare an additional power supply for driving.

[0016] Also, since the power supply of the secondary side inverter is a capacitor, it can supply only reactive power. Therefore, the primary side inverter INV1 outputs the active voltage of the voltage command value, and the secondary side inverter INV2 outputs the reactive voltage. Also, the primary side inverter INV1 also bears the reactive voltage that cannot be output by the secondary side inverter INV2.

[0017] Here, let the active power be P, the reactive power be Q, the active voltage be V real , and the reactive voltage be V imag . Then, their relationship is as shown in the vector diagram of FIG. 11 and is defined by the following mathematical formulas (I) to (III). That is, the apparent power S is defined as the product (the outer product in the vector) of the motor current I m and the motor applied voltage V m .

[0018] Also, the active power P is the product of the active voltage V m that is in the same phase as the motor current I m of the motor applied voltage V real and the motor current I m . Further, the reactive power Q is the product of the reactive voltage V m that is in the direction orthogonal to the motor current I m of the motor applied voltage V imag and the motor current Im It is defined by the product of

[0019]

Number

[0020] In the power conversion device of the floating capacitor type dual inverter shown in FIG. 10, as described above, the primary inverter INV1 can output active power P and reactive power Q, and the secondary inverter INV2 can output only reactive power Q. Therefore, with the control as shown in the block diagram of FIG. 12, the voltage command values of the primary inverter INV1 and the secondary inverter INV2 are distributed according to the following mathematical formulas (IV) and (V) to drive the motor M.

[0021]

Number

[0022] In addition, in FIGS. 12, (IV), and (V), v d ref is the d-axis voltage command value, v q ref is the q-axis voltage command value, i d is the d-axis current, i q is the q-axis current, θ Im is the motor current phase, v d1 ref is the d-axis voltage command value of the primary inverter INV1, v q1 ref is the q-axis voltage command value of the primary inverter INV1, v d2 ref is the d-axis voltage command value of the secondary inverter INV2, v q2 ref is the q-axis voltage command value of the secondary inverter INV2.

[0023] Furthermore, in the power conversion device of the floating capacitor type dual inverter, in addition to driving the motor M, it is necessary to control the DC link voltage of the secondary inverter INV2, that is, the secondary voltage Vdc2, and the components of the voltage vector required for charging the capacitor C will be added.

[0024] In this case, in the power conversion device of the floating capacitor type dual inverter, since no zero-phase current flows, the motor current I m and the voltage vector are used to control the secondary-side voltage V dc2 . That is, as shown in FIG. 13, by controlling the phase difference of the voltage vector between the primary-side inverter INV1 and the secondary-side inverter INV2, etc., the charging mode and the discharging mode of the secondary-side voltage V dc2 are controlled.

[0025] Specifically, the output voltage vector V2 of the secondary-side inverter INV2 is brought closer to the current phase while being advanced by 90 deg with respect to the current phase (+β) for the charging mode, and further advanced in phase (-β) for the discharging mode. In addition to this method, there are various ways of setting the phase difference and distributing the vectors. In such a power conversion device of a floating capacitor type dual inverter, since the motor M can be driven while boosting the capacitor C provided in the secondary-side inverter INV2, there is an advantage that the voltage that can be applied to the motor M can be made higher than that of the power supply common type.

[0026] However, all of the conventional dual inverter type power conversion devices described above have an increased number of components, making it difficult to reduce costs and size. In particular, in the power conversion device of a floating capacitor type dual inverter, since the secondary-side inverter INV2 has a floating potential, in addition to the gate drive power supply for the switching element of the primary-side inverter INV1, it is necessary to create a gate drive power supply (insulated power supply) for the switching element of the secondary-side inverter INV2 with a different reference potential. In a device with limited board area, such as an in-vehicle electric compressor, it has been difficult to adopt it in terms of component mounting area and cost.

[0027] Therefore, the applicant previously proposed a power conversion device as shown in Fig. 1. In this method, the positive power supply line of the power supply common type shown in Fig. 8 is separated by the primary inverter INV1 and the secondary inverter INV2, and only the negative power supply line is shared. A capacitor is arranged on the secondary side like the floating capacitor type shown in Fig. 10. Hereinafter, the power conversion device of this method is referred to as a GND common type dual inverter. In this method, the secondary side voltage can be controlled in the same manner as the control of the power conversion device of the floating capacitor type dual inverter described with reference to Figs. 11 to 13.

[0028] Also, in the power conversion device of the GND common type dual inverter, it is possible to share the power supply of the drive circuit of the secondary inverter INV2 in the same manner as the power supply common type. And it is possible to configure the primary inverter INV1 on the power supply side with high withstand voltage components and the controllable secondary inverter INV2 with low withstand voltage components. The GND common type in which the power supply of the drive circuit of the secondary inverter INV2 can be shared with the primary inverter INV1 has great advantages in applications where the power supply voltage fluctuates greatly.

[0029] However, in such a power conversion device of the GND common type dual inverter, a zero-phase current flows, so it is necessary to perform zero-phase current control. That is, due to the property that a zero-phase current flows in the secondary side voltage control, there is a problem that the same control as the floating capacitor type cannot be applied. Also, it is necessary to simultaneously control the secondary side voltage and the motor control, and complex control is required. Furthermore, similar to the floating capacitor type, the primary inverter INV1 can output the active voltage and the reactive voltage of the voltage command value, and the secondary inverter INV2 can only output the reactive voltage. However, until now, a control theory for the GND common type that drives a motor with an open-end winding structure while stably controlling the secondary side voltage has not been established.

[0030] The present invention is made to solve such a conventional technical problem, and while stably controlling the secondary-side voltage of the above GND common type dual inverter, it provides a power conversion device capable of driving a motor having a winding with an open-end structure.

Means for Solving the Problem

[0031] In order to stably control the power conversion device of the above GND common type dual inverter, for the control of the secondary-side voltage, the existing vector control of dq-axis current as shown in FIG. 7 is applied and modeled.

[0032] That is, the power conversion device of the present invention includes a primary-side inverter connected to one end of a winding with an open-end structure that the motor has, and a secondary-side inverter connected to the other end of the winding, and applies the differential voltage between the primary-side inverter and the secondary-side inverter to the motor. The primary-side inverter is connected to a DC power supply, the secondary-side inverter is connected to a capacitor, the negative power supply lines of the primary-side inverter and the secondary-side inverter are commonized, and the secondary-side voltage V which is the charging voltage of the capacitor dc2 is provided with a control device for controlling it. This control device has a secondary-side voltage control system that generates a zero-phase voltage command value v dc2 for flowing a secondary-side DC link current necessary for controlling the secondary-side voltage V dc2 ref to a secondary-side voltage command value V z ref and is characterized by this.

[0033] The power conversion device according to the invention of claim 2 is characterized in that, in the above invention, the primary side inverter and the secondary side inverter are each composed of a plurality of switching elements. The positive input terminal of the primary side inverter is connected to the positive power supply line of the DC power supply, the negative input terminal of the primary side inverter is connected to the negative power supply line of the DC power supply, the output terminal of the primary side inverter is connected to one end of the winding, the output terminal of the secondary side inverter is connected to the other end of the winding, a capacitor is connected between the positive input terminal and the negative input terminal of the secondary side inverter, the positive input terminal of the secondary side inverter is not connected to the positive power supply line of the DC power supply, the negative input terminal of the secondary side inverter is connected to the negative power supply line of the DC power supply, and an AC output is generated from the DC power supply by switching each switching element by a control device.

[0034] The power conversion device according to the invention of claim 3 is characterized in that, in the invention of claim 1, the control device adopts the capacitor current flowing through the capacitor as the secondary side DC link current, or adopts the zero-phase current i as an index indicating the secondary side DC link current. z as a feature.

[0035] The power conversion device according to the invention of claim 4 is characterized in that, in the invention of claim 1, the secondary side voltage control system includes a secondary side voltage control unit that generates a secondary side DC link current command value necessary for controlling the secondary side voltage V, a secondary side DC link current control unit that controls the secondary side DC link current to the secondary side DC link current command value to generate a zero-phase voltage command value v, and an output voltage command generation unit that generates a primary side output voltage command value v for switching the primary side inverter and a secondary side output voltage command value v for switching the secondary side inverter based on the zero-phase voltage command value v. dc2 and a secondary side DC link current control unit for controlling the secondary side DC link current to the secondary side DC link current command value to generate a zero-phase voltage command value v, and an output voltage command generation unit that generates a primary side output voltage command value v for switching the primary side inverter and a secondary side output voltage command value v for switching the secondary side inverter based on the zero-phase voltage command value v. z ref and an output voltage command generation unit that generates a primary side output voltage command value v for switching the primary side inverter and a secondary side output voltage command value v for switching the secondary side inverter based on the zero-phase voltage command value v. z ref Based on the zero-phase voltage command value v, a primary side output voltage command value v for switching the primary side inverter and a secondary side output voltage command value v for switching the secondary side inverter are generated. uvw1 ref and a secondary side output voltage command value v for switching the secondary side inverter. uvw2 ref The power conversion device according to the invention of claim 5 is characterized in that, in the above invention, the control device has a zero-phase current i.

[0036] The power conversion device according to the invention of claim 5 is characterized in that, in the above invention, the control device has a zero-phase current i. zis adopted as an index indicating the secondary-side DC link current, and the secondary-side voltage control unit controls the secondary-side voltage command value V dc2 ref to generate a zero-phase current command value i z ref based on it. The secondary-side DC link current control unit generates a zero-phase voltage command value v z ref based on the zero-phase current command value i z ref The output voltage command generation unit generates a primary-side output voltage vector command value and a secondary-side output voltage vector command value from the dq-axis voltage command value v dq ref and generates a primary-side output voltage command value v uvw1 ref from the primary-side output voltage vector command value and a secondary-side output voltage command value v uvw2 ref from the secondary-side output voltage vector command value, which is characterized by this.

[0037] In the power conversion device according to the invention of claim 6, in the above invention, the output voltage command generation unit adds the zero-phase voltage command value v z ref to the primary-side output voltage vector command value and / or the secondary-side output voltage vector command value to generate the primary-side output voltage command value v uvw1 ref and the secondary-side output voltage command value v uvw2 ref which is characterized by this.

[0038] In the power conversion device according to the invention of claim 7, in the above invention, the output voltage command generation unit has a zero-phase voltage distribution unit that distributes the zero-phase voltage command value v z ref to the primary-side output voltage vector command value and the secondary-side output voltage vector command value, which is characterized by this.

[0039] In the power conversion device according to the invention of claim 8, in the above invention, the zero-phase voltage distribution unit has a case where the gain M1 for distributing to the primary-side output voltage vector command value is 1 and the gain M2 for distributing to the secondary-side output voltage vector command value is 0, which is characterized by this.

[0040] The power conversion device according to the invention of claim 9 is characterized in that, in the invention of claim 7, the zero-phase voltage distribution unit has a case where the gain M1 distributed to the primary-side output voltage vector command value is 0 and the gain M2 distributed to the secondary-side output voltage vector command value is 1.

[0041] The power conversion device according to the invention of claim 10 is such that, in the invention of claim 5, the output voltage command generation unit decomposes the dq-axis voltage command value v dq ref into the effective voltage V real as the primary-side output voltage vector command value and the reactive voltage V imag as the secondary-side output voltage vector command value, generates the primary-side output voltage command value v real from the effective voltage V uvw1 ref , and generates the secondary-side output voltage command value v imag from the reactive voltage V uvw2 ref .

[0042] The power conversion device according to the invention of claim 11 is such that, in the above invention, the output voltage command generation unit generates the primary-side output voltage command value v real and / or the secondary-side output voltage command value v imag by adding the zero-phase voltage command value v z ref to the effective voltage V uvw1 ref and the reactive voltage V uvw2 ref .

[0043] The power conversion device according to the invention of claim 12 is such that, in the above invention, the output voltage command generation unit has a zero-phase voltage distribution unit that distributes the zero-phase voltage command value v real to the effective voltage V imag and the reactive voltage V z ref .

[0044] The power conversion device according to the invention of claim 13 is such that, in the above invention, the zero-phase voltage distribution unit has a gain M1 of 1 distributed to the effective voltage V real and a gain of imagIt is characterized by having a case where the gain M2 to be distributed is set to 0.

[0045] In the power conversion device of the invention according to claim 14, in the invention according to claim 12, the zero-phase voltage distribution unit has a case where the gain M1 to be distributed to the effective voltage V real is 0, and the gain M2 to be distributed to the reactive voltage V imag is 1.

[0046] In the power conversion device of the invention according to claim 15, in the inventions according to claims 5 to 14, the secondary-side DC link current control unit controls the zero-phase current i z to the zero-phase current command value i z ref by generating a zero-phase voltage command value v z ref

Advantages of the Invention

[0047] According to the present invention, in a power conversion device including a primary-side inverter connected to one end of a winding having an open-end structure of a motor and a secondary-side inverter connected to the other end of the winding, and applying a differential voltage between the primary-side inverter and the secondary-side inverter to the motor, the primary-side inverter is connected to a DC power supply, the secondary-side inverter is connected to a capacitor, and the negative power supply lines of the primary-side inverter and the secondary-side inverter are commonized, so that the capacitor is charged by the secondary-side inverter via the motor from the DC power supply, and an AC output is applied to the motor using the voltage charged in the capacitor by the secondary-side inverter, thereby expanding the drivable region with respect to changes in the input voltage.

[0048] Further, in the power conversion device of the GND common type dual inverter, as in the invention of claim 2, the positive input terminal of the secondary-side inverter is not connected to the positive power supply line of the DC power supply, and the negative input terminal of the secondary-side inverter is connected to the negative power supply line of the DC power supply. Therefore, the secondary-side inverter does not have a floating potential, and the reference voltages of the primary-side inverter and the secondary-side inverter are aligned. ​

[0049] As a result, it becomes unnecessary to create a gate drive power supply (isolated power supply) for the switching element of the secondary-side inverter separately from the gate drive power supply (isolated power supply) for the switching element of the primary-side inverter, and the switching element of the primary-side inverter and the switching element of the secondary-side inverter can be switched by a common gate drive power supply. Therefore, it is possible to expand the drivable region with respect to changes in the input voltage without using a separate boost converter or the like.

[0050] In addition, since there is no need to create a gate drive power supply for each inverter, an increase in the component mounting area can be suppressed, and miniaturization and cost reduction can be achieved. Therefore, in devices such as in-vehicle electric compressors where the input voltage changes greatly, the requirement for cost reduction is strong, and the substrate area is limited and miniaturization of the power conversion device is required, this is extremely effective.

[0051] In particular, in the present invention, a control device for controlling the secondary-side voltage V dc2 which is the charging voltage of the capacitor is provided, and this control device controls the secondary-side voltage V dc2 to the secondary-side voltage command value V dc2 ref by flowing a zero-phase voltage command value v z ref which is the necessary secondary-side DC link current. Since it has a secondary-side voltage control system that generates dc2 modeling of the secondary-side voltage V dc2 and design of the control system become possible, design of the responsiveness of the secondary-side voltage V

[0052] z z z zThis is because it becomes the substantially secondary-side DC link current. However, when using the capacitor current, a sensor for detecting the current flowing through the capacitor is separately required. But if it is the zero-phase current i z then, the control device can detect it from each phase current i uvw

[0053] Furthermore, like the invention of claim 4, when the secondary-side voltage control system includes a secondary-side voltage control unit that generates a secondary-side DC link current command value necessary for controlling the secondary-side voltage V dc2 a secondary-side DC link current control unit that controls the secondary-side DC link current to the secondary-side DC link current command value, and a zero-phase voltage command value v z ref for generating, and an output voltage command generation unit that generates a primary-side output voltage command value v z ref for switching the primary-side inverter and a secondary-side output voltage command value v uvw1 ref for switching the secondary-side inverter based on the zero-phase voltage command value v uvw2 ref a more stable secondary-side voltage control and motor drive control can be performed.

[0054] And when adopting the zero-phase current i z as an index indicating the secondary-side DC link current, like the invention of claim 5, the secondary-side voltage control unit of the control device generates a zero-phase current command value i dc2 ref based on the secondary-side voltage command value V z ref the secondary-side DC link current control unit generates a zero-phase voltage command value v z ref based on the zero-phase current command value i z ref the output voltage command generation unit generates a primary-side output voltage vector command value and a secondary-side output voltage vector command value from the dq-axis voltage command value v dq ref generates a primary-side output voltage command value v uvw1 ref from the primary-side output voltage vector command value, and generates a secondary-side output voltage command value v​uvw2 ref will be generated.

[0055] Also, as in the invention of claim 6, the output voltage command generation unit adds the zero-phase voltage command value v to the primary-side output voltage vector command value and / or the secondary-side output voltage vector command value, z ref to obtain the primary-side output voltage command value v uvw1 ref and the secondary-side output voltage command value v uvw2 ref will be generated. However, as in the invention of claim 7, a zero-phase voltage distribution unit that distributes the zero-phase voltage command value v to the primary-side output voltage vector command value and the secondary-side output voltage vector command value is provided in the output voltage command generation unit. As in the invention of claim 8, the zero-phase voltage distribution unit has cases where the gain M1 distributed to the primary-side output voltage vector command value is 1 and the gain M2 distributed to the secondary-side output voltage vector command value is 0. As in the invention of claim 9, the zero-phase voltage distribution unit has cases where the gain M1 distributed to the primary-side output voltage vector command value is 0 and the gain M2 distributed to the secondary-side output voltage vector command value is 1, which increases the degree of freedom of control. If the gain M1 distributed to the primary-side output voltage vector command value is 1 and the gain M2 distributed to the secondary-side output voltage vector command value is 0, z ref the zero-phase voltage command value v is borne by the primary-side inverter with the higher voltage, z ref and there is an effect that the operating range can be ensured.

[0056] In addition, as the primary-side output voltage vector command value and the secondary-side output voltage vector command value in the inventions of claims 5 to 9 above, the effective voltage V real and the reactive voltage V imag as in the inventions of claims 10 to 14 can be adopted.

[0057] Also, as in the invention of claim 15, the secondary-side DC link current control unit controls the zero-phase current i z to the zero-phase current command value i z ref by the zero-phase voltage command value v zref By generating this, it becomes possible to prevent the runaway of the zero-phase current i by feedback control. z

Brief Description of the Drawings

[0058]

Figure 1

Figure 2

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Figure 12

Figure 13

Mode for Carrying Out the Invention

[0059] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (1) Power conversion device 1 FIG. 1 is an electrical circuit diagram of a power conversion device 1 of a GND common type dual inverter to which the present invention is applied. The power conversion device 1 of the embodiment converts the DC voltage V dc (for example, DC500V) of a DC power supply (for example, a high voltage battery of an electric vehicle) 2 into a three-phase AC voltage (AC output) and supplies it to the motor M. The motor M of the embodiment is composed of a stator with windings and a rotor with a built-in magnet that rotates inside it, and is a three-phase permanent magnet synchronous motor (Interior Permanent Magnet Synchronous Motor) that drives an electric compressor used in an air conditioning device of an electric vehicle such as an electric vehicle or a hybrid vehicle. Note that the DC voltage V dc of the DC power supply 2 is the primary side voltage V dc1 described later.

[0060] In the case of the embodiment, the power conversion device 1 includes a three-phase primary side inverter INV1 composed of upper and lower arm switching elements 3A to 3F, a three-phase secondary side inverter INV2 composed of upper and lower arm switching elements 4A to 4F, a control device 6 (FIG. 2), and the like. Note that each of the switching elements 3A to 3F and 4A to 4F is composed of an insulated gate bipolar transistor (IGBT) incorporating a MOS structure in the gate portion in the embodiment.

[0061] In this invention, the primary side inverter INV1 and the secondary side inverter INV2 convert the DC voltage V dc of the DC power supply 2 into a three-phase AC voltage (AC output), and apply the differential voltage between the inverters INV1 and INV2 to the windings (stator windings) 7U, 7V, and 7W of the motor M. Here, the windings 7U, 7V, and 7W of the motor M have an open end structure that is not bundled at the neutral point.

[0062] (2) Primary-side inverter INV1 The primary-side inverter INV1 has a half-bridge circuit 9U for the U phase, a half-bridge circuit 9V for the V phase, and a half-bridge circuit 9W for the W phase. Each half-bridge circuit 9U - 9W of each phase individually has the upper-arm switching elements 3A - 3C and the lower-arm switching elements 3D - 3F described above. Furthermore, each of the switching elements 3A - 3F incorporates a freewheeling diode connected in antiparallel.

[0063] And the collector electrodes of the upper-arm switching elements 3A - 3C, which are the positive input terminals of the primary-side inverter INV1, are connected to the positive power line 11 (HV+) of the DC power supply 2. On the other hand, the emitter electrodes of the lower-arm switching elements 3D - 3F, which are the negative input terminals of the primary-side inverter INV1, are connected to the negative power line 12 (HV-) of the DC power supply 2. Note that 13 in the figure is a capacitor connected between the positive power line 11 and the negative power line 12, which constitutes a noise filter.

[0064] In the primary-side inverter INV1, the emitter electrode of the upper-arm switching element 3A of the half-bridge circuit 9U for the U phase and the collector electrode of the lower-arm switching element 3D are connected, and their connection point (arm midpoint: the output terminal of the primary-side inverter INV1) is connected to one end of the winding 7U of the U phase of the motor M.

[0065] Also, the emitter electrode of the upper-arm switching element 3B of the half-bridge circuit 9V for the V phase and the collector electrode of the lower-arm switching element 3E are connected, and their connection point (arm midpoint: the output terminal of the primary-side inverter INV1) is connected to one end of the stator winding 7V of the V phase of the motor M.

[0066] Furthermore, the emitter electrode of the upper-arm switching element 3C of the half-bridge circuit 9W for the W phase and the collector electrode of the lower-arm switching element 3F are connected, and their connection point (arm midpoint: the output terminal of the primary-side inverter INV1) is connected to one end of the stator winding 7W of the W phase of the motor M.

[0067] (3) Secondary-side inverter INV2 The secondary-side inverter INV2 also includes three half-bridge circuits 16U, 16V, and 16W corresponding to each phase of UVW. And the neutral points of each phase of the motor M are not bundled, and the half-bridge circuits 9U to 9W of the primary-side inverter INV1 and the half-bridge circuits 16U to 16W of the secondary-side inverter INV2 are configured to sandwich the windings 7U to 7W of the motor M.

[0068] The half-bridge circuits 16U to 16W of the secondary-side inverter INV2 also individually have upper-arm switching elements 4A to 4C and lower-arm switching elements 4D to 4F. Also, each of the switching elements 4A to 4F incorporates a freewheeling diode connected in antiparallel.

[0069] And a capacitor C (capacitor) is connected between the collector electrodes of the upper-arm switching elements 4A to 4C which are the positive input terminals of the secondary-side inverter INV2 and the emitter electrodes of the lower-arm switching elements 4D to 4F which are the negative input terminals of the secondary-side inverter INV2.

[0070] However, the collector electrodes of the upper-arm switching elements 4A to 4C which are the positive input terminals of the secondary-side inverter INV2 are not connected to the positive power line 11 of the DC power supply 2 and are disconnected. On the other hand, in the present invention, the emitter electrodes H of the lower-arm switching elements 4D to 4F which are the negative input terminals of the secondary-side inverter INV2 are connected to the negative power line 12 of the DC power supply 2.

[0071] And the emitter electrode of the upper-arm switching element 4A and the collector electrode of the lower-arm switching element 4D of the half-bridge circuit 16U of the U phase are connected, and their connection point (arm midpoint: output terminal of the secondary-side inverter INV2) is connected to the other end of the U-phase winding 7U of the motor M.

[0072] Also, the emitter electrode of the upper arm switching element 4B of the V-phase half-bridge circuit 16V and the collector electrode of the lower arm switching element 4E are connected, and their connection point (arm midpoint: output end of the secondary inverter INV2) is connected to the other end of the stator winding 7V of the V-phase of the motor M.

[0073] Furthermore, the emitter electrode of the upper arm switching element 4C of the W-phase half-bridge circuit 16W and the collector electrode of the lower arm switching element 4F are connected, and their connection point (arm midpoint: output end of the secondary inverter INV2) is connected to the other end of the stator winding 7W of the W-phase of the motor M. That is, the power conversion device 1 of the present invention has the configuration of the aforementioned GND common type dual inverter method.

[0074] (4) Control device 6 Next, FIG. 2 shows a block diagram of the control device 6. The control device 6 of the embodiment is composed of a microcomputer having a processor, and receives a speed command value ω rm ref and a secondary voltage command value v dc2 ref from the ECU of the electric vehicle, and inputs the phase current of the motor M from a current sensor (not shown). Based on these, it controls (switches) the ON / OFF states of the switching elements 3A to 3F and 4A to 4F of the primary inverter INV1 and the secondary inverter INV2.

[0075] Specifically, it controls the gate voltage applied to the gates of the switching elements 3A to 3F and 4A to 4F. Also, the control device 6 of the embodiment has a configuration including a speed control unit 21, a dq-axis current control unit 22, a secondary voltage control system 23, a primary modulation unit 24, a secondary modulation unit 26, and the like.

[0076] The speed control unit 21 calculates and outputs a q-axis current command value i q based on the PI operation and the relational expression between the q-axis current i q ref and torque. The dq-axis current control unit 22 calculates a d-axis voltage command value v d refand the q-axis voltage command value v q ref are calculated and output. In this case, in the dq-axis current control unit 22, basically, the d-axis current command value i d ref and the d-axis current i d (estimated value), the q-axis current command value i q ref and the q-axis current i q (estimated value) are used to eliminate the deviation in the direction of the d-axis voltage command value v d ref and the q-axis voltage command value v q ref are calculated.

[0077] The secondary-side voltage control system 23 generates a zero-phase voltage command value v dc2 for flowing the secondary-side DC link current (in the embodiment, the zero-phase current i dc2 ref is adopted as an index indicating the secondary-side DC link current) required to control the secondary-side voltage V z to the secondary-side voltage command value V z ref . Then, from the d-axis current i d (estimated value), the q-axis current i q (estimated value), the d-axis voltage command value v d ref and the q-axis voltage command value v q ref output by the dq-axis current control unit 22, and the above zero-phase voltage command value v z ref , the primary-side output voltage command values v u1 ref , v v1 ref , v w1 ref for switching each switching element 3A to 3F of the primary-side inverter INV1, and the secondary-side output voltage command values v u2 ref , v v2 ref , v w2 ref for switching each switching element 4A to 4F of the secondary-side inverter INV2 are generated and output. The operation of this secondary-side voltage control system 23 will be described in detail later.

[0078] The primary-side modulation unit 24 generates and outputs a primary-side inverter switching signal (PWM signal) for switching (PWM control) each of the switching elements 3A to 3F of the primary-side inverter INV1 from the primary-side output voltage command values v u1 ref 、v v1 ref 、v w1 ref 。 Further, the secondary-side modulation unit 26 generates and outputs a secondary-side inverter switching signal (PWM signal) for switching (PWM control) each of the switching elements 4A to 4F of the secondary-side inverter INV2 from the secondary-side output voltage command values v u2 ref 、v v2 ref 、v w2 ref 。

[0079] (5) Secondary-side voltage control system 23 Next, with reference to FIGS. 3 to 6, the detailed configuration and operation of the secondary-side voltage control system 23 of the embodiment will be described. In the case of this embodiment, the secondary-side voltage control system 23 has a configuration including a secondary-side voltage control unit 27, a secondary-side DC link current control unit 28, and an output voltage command generation unit 29.

[0080] Here, the equivalent circuit of the zero-phase component of the power conversion device 1 in FIG. 1 is as shown in the lower part of FIG. 3. The equivalent circuit in the lower part of FIG. 3 can be regarded as a chopper circuit of a buck chopper and a boost chopper. Note that V dc1 in the figure is the DC voltage of the DC power supply 2, which is the aforementioned primary-side voltage. Also, C dc2 is the capacitance of the capacitor C, L z is the self-inductance of the z-axis of the motor M, and R a is the internal resistance.

[0081] From this equivalent circuit, the zero-phase voltage v z1 of the primary-side inverter INV1 and the zero-phase voltage v z2 of the secondary-side inverter INV2, the zero-phase voltage v z (=v z1 -v z2By controlling the zero-phase current i z it can be seen that it is possible to control the secondary-side voltage v dc2 . Therefore, the control device 6 of this embodiment adopts the zero-phase current i z as an index indicating the secondary-side DC link current. This is based on the fact that the zero-phase current i z substantially coincides with the secondary-side DC link current.

[0082] On the premise that the zero-phase component (z-axis) of the power conversion device 1 can be equivalently represented by a chopper circuit as described above, when modeling the controller (controller) and the controlled object (plant model) for the power conversion device 1 in FIG. 1, it becomes as shown in FIG. 4. In this case, the plant model of the controlled object assumes an LR load for the model from voltage (the following v z -e z ) to current (zero-phase current i z ) in the same way as the dq axes, and the model from the zero-phase current i z to the secondary-side voltage V dc2 (shown as 32 in the figure) is modeled as a simple capacitor. Incidentally, ω re is the electrical angular velocity, and θ re is the rotor position.

[0083] Also, for the control system, a voltage PI control system 33 that performs secondary-side voltage control outputs a zero-phase current command value i z ref , and a current PI control system 34 that controls the zero-phase current i z outputs a zero-phase voltage command value v z ref . Then, the non-interference voltage command value e z that compensates for the induced voltage component e z est excited on the z-axis by the rotation of the motor M is added to the zero-phase voltage command value v z ref and output as the zero-phase voltage v z . Thereby, as described above, the design of the controller for the power conversion device 1 in FIG. 1 becomes possible.

[0084] Incidentally, for the secondary-side voltage V by the z-axis control system as described abovedc2 The control is affected by the controllability of the zero-phase current i z In the model of FIG. 4, since PI control is applied, it has sufficient performance to control the DC component (direct current component) of the secondary-side voltage V dc2 However, due to parameter errors such as those of the non-interference voltage command value e z est when a ripple occurs in the zero-phase current zero-phase current i z a ripple is also excited in the secondary-side voltage V dc2 Therefore, from the perspective of voltage quality, by adopting a controller that suppresses the AC component (periodic disturbance component), such as periodic disturbance suppression control, sine wave tracking control, repetitive control, etc., advanced current control can be performed.

[0085] The block diagram of the secondary-side voltage control system 23 designed by the above modeling is shown in FIG. 5. In the upper left of this FIG. 5, the voltage PI control system 33 of FIG. 4 constitutes the secondary-side voltage control unit 27 of FIG. 2, and this secondary-side voltage control unit 27 outputs the zero-phase current command value i z ref (the secondary-side DC link current command value necessary for controlling the secondary-side voltage V dc2 in the present invention). Also, the current PI control system 34 of FIG. 4 constitutes the secondary-side DC link current control unit 28 of FIG. 2, and this secondary-side DC link current control unit 28 outputs the zero-phase voltage command value v z for controlling the zero-phase current i z ref (the secondary-side DC link current in the present invention) to the zero-phase current command value i z ref (the secondary-side DC link current command value in the present invention).

[0086] In the case of the embodiment, the value obtained by feeding back and subtracting the zero-phase current i z ref from the zero-phase current command value i z output by the voltage PI control system 33 is input to the current PI control system 34 that constitutes the secondary-side DC link current control unit 28. And the current PI control system 34 of the secondary-side DC link current control unit 28 is the zero-phase current command value i z ref and the zero-phase current i zCalculate the zero-phase voltage command value v in the direction of eliminating the difference from z ref and control the zero-phase current i z to the zero-phase current command value i z ref .

[0087] The block shown below it is the output voltage command generation unit 29 in FIG. 2. The basic control block of this output voltage command generation unit 29 is the same as that of the floating capacitor type dual inverter power conversion device shown in FIG. 12. That is, the output voltage command generation unit 29 of this embodiment has an active / inactive decomposition unit 36, and this active / inactive decomposition unit 36 decomposes the d-axis voltage command value v d ref and the q-axis voltage command value v q ref into the active voltage V real and the reactive voltage V imag by the aforementioned mathematical formula (IV). This active voltage V real is an example of the primary side output voltage vector command value in the present invention, and the reactive voltage V imag is an example of the secondary side output voltage vector command value in the present invention.

[0088] The output voltage command generation unit 29 uses the aforementioned mathematical formula (V) to set the active voltage V decomposed as above real as the d-axis voltage command value v of the primary side inverter INV1 d1 ref , and sets the q-axis voltage command value v of the primary side inverter INV1 q1 ref to 0. Also, the d-axis voltage command value v of the secondary side inverter INV2 d2 ref is set to 0, and the reactive voltage V imag is set as the q-axis voltage command value v of the secondary side inverter INV2 q2 ref .

[0089] Next, by the dq-uvw conversion unit 37 included in the output voltage command generation unit 29, the d-axis voltage command value v of the primary side inverter INV1 d1 ref and the q-axis voltage command value v of the primary side inverter INV1 q1ref is converted into the output voltage command values of each phase uvw of the primary-side inverter INV1, and the dq-uvw conversion unit 38 converts it into the d-axis voltage command value v d2 ref of the secondary-side inverter INV2, and the q-axis voltage command value v q2 ref of the secondary-side inverter INV2 is converted into the output voltage command values of each phase uvw of the secondary-side inverter INV2.

[0090] In addition, the output voltage command generation unit 29 has a zero-phase voltage distribution unit 39. This zero-phase voltage distribution unit 39 distributes the zero-phase voltage command value v z ref output by the secondary-side DC link current control unit 28 to each inverter INV1 and INV2 with a gain M1 for distribution to the primary-side inverter INV1 and a gain M2 for distribution to the secondary-side inverter INV2. Then, the adder 41 adds the zero-phase voltage command value v z ref multiplied by the gain M1 to the output voltage command values of each phase uvw of the primary-side inverter INV1 output by the dq-uvw conversion unit 37, and outputs the primary-side output voltage command values v u1 ref 、v v1 ref 、v w1 ref At the same time, the adder 42 adds the zero-phase voltage command value v z ref multiplied by the gain M2 to the output voltage command values of each phase uvw of the secondary-side inverter INV2 output by the dq-uvw conversion unit 38, and outputs the secondary-side output voltage command values v u2 ref 、v v2 ref 、v w2 ref as output.

[0091] That is, the active voltage V real as the primary-side output voltage vector command value and the reactive voltage V imag as the secondary-side output voltage vector command value (actually the values obtained by converting them into the output voltage command values of each phase uvw) are added with the zero-phase voltage command value v z refBy distributing and adding, the primary-side output voltage command value v u1 ref , v v1 ref , v w1 ref and the secondary-side output voltage command value v u2 ref , v v2 ref , v w2 ref are generated and output.

[0092] Here, gain M1 + gain M2 = 1. Also, the zero-phase voltage distribution unit 39 has the cases where gain M1 = 1 and gain M2 = 0, and where gain M1 = 0 and gain M2 = 1. Therefore, the zero-phase voltage command value v z ref may be added to the output voltage command values of each phase uvw of either one of the inverters INV1 and INV2, and not added to the other.

[0093] Basically, the zero-phase voltage command value v z ref may be added to the output voltage command values of each phase uvw of the inverters INV1 and INV2 output by the dq-uvw converters 37 and 38 respectively. However, considering the operating range and the like, it is better for the primary-side inverter INV1 on the side with a higher voltage to bear the burden. In that case, the zero-phase voltage distribution unit 39 sets gain M1 = 1 and gain M2 = 0, and makes only the primary-side inverter INV1 bear the zero-phase voltage command value v z ref .

[0094] In addition, the sign of the zero-phase voltage command value v z ref multiplied by the gain M2 added in the adder 42 is set to - (i.e., subtracted). This is because it is necessary to create a potential difference of the zero-phase voltage v z between the primary-side inverter INV1 and the secondary-side inverter INV2. The adder 42 actually becomes a subtractor, and adds the value obtained by making the zero-phase voltage command value v z ref multiplied by the gain M2 negative to the output voltage command values of each phase uvw.

[0095] In this way, based on the zero-phase voltage command value v z ref the output voltage command generation unit 29 generates the primary-side output voltage command values v u1 ref 、v v1 ref 、v w1 ref for switching the primary-side inverter INV1, and the secondary-side output voltage command values v u2 ref 、v v2 ref 、v w2 ref for switching the secondary-side inverter INV2, and outputs them.

[0096] The primary-side modulation unit 24 generates and outputs a primary-side inverter switching signal (PWM signal) for switching each switching element 3A to 3F of the primary-side inverter INV1 from the primary-side output voltage command values v u1 ref 、v v1 ref 、v w1 ref output by the output voltage command generation unit 29. Further, the secondary-side modulation unit 26 generates and outputs a secondary-side inverter switching signal (PWM signal) for switching each switching element 4A to 4F of the secondary-side inverter INV2 from the secondary-side output voltage command values v u2 ref 、v v2 ref 、v w2 ref output by the output voltage command generation unit 29.

[0097] Fig. 6 shows the situation of each parameter when the motor M is driven by the control device 6 according to FIG. 6. In this figure, the uppermost row represents the speed of the motor M, the solid line represents the speed Spd c of the motor M read by the control device 6, and the broken line represents the speed command value Spd ref The second row from the top is the d-axis current i d and the solid line represents the d-axis current value id c The broken line is the d-axis current command value i d ref as shown. The third row from the top is the q-axis current i q and the solid line is the q-axis current value i read by the control device 6 q c The broken line is the q-axis current command value i q ref as shown.

[0098] The second row from the bottom in FIG. 6 is the zero-phase current i z and the solid line is the zero-phase current value i read by the control device 6 z c The broken line is the zero-phase current command value i z ref as shown. And the bottom row is the secondary-side DC link voltage, that is, the secondary-side voltage V dc2 and the thin solid line is the actual secondary-side voltage V dc2 The solid line is the secondary-side voltage V read by the control device 6 dc2 c The broken line is the secondary-side voltage command value V dc2 ref as shown. It can be seen that the values read by the control device 6 for any of the parameters all follow the respective command values well.

[0099] As described in detail above, according to the present invention, since the primary-side inverter INV1 is connected to the DC power supply 2, the secondary-side inverter INV2 is connected to the capacitor C, and the negative power supply lines 12 of the primary-side inverter INV1 and the secondary-side inverter INV2 are made common, that is, a GND common type dual inverter, it is possible to charge the capacitor C by the secondary-side inverter INV2 from the DC power supply 2 via the motor M, and by applying an AC output to the motor M using the voltage charged to the capacitor C by the secondary-side inverter INV2, it becomes possible to expand the drivable region with respect to changes in the input voltage.

[0100] In the power conversion device 1 of the GND common type dual inverter, since the positive input terminal of the secondary inverter INV2 is not connected to the positive power supply line 11 of the DC power supply 2 and the negative input terminal of the secondary inverter INV2 is connected to the negative power supply line 12 of the DC power supply 2, the secondary inverter INV2 does not have a floating potential, and the reference voltages of the primary inverter INV1 and the secondary inverter INV2 will be the same.

[0101] As a result, it is no longer necessary to create a gate drive power supply (isolated power supply) for the switching elements 4A to 4F of the secondary inverter INV2 separately from the gate drive power supply (isolated power supply) for the switching elements 3A to 3F of the primary inverter INV1. The switching elements 3A to 3F of the primary inverter INV1 and the switching elements 4A to 4F of the secondary inverter INV2 can be switched by a common gate drive power supply, so it becomes possible to expand the drivable region with respect to changes in the input voltage without using a separate boost converter or the like.

[0102] In addition, since there is no need to create a gate drive power supply for each of the inverters INV1 and INV2, an increase in the component mounting area can be suppressed, and miniaturization and cost reduction can be achieved. Therefore, in equipment such as in-vehicle electric compressors where the input voltage changes greatly, the requirement for cost reduction is strong, and the substrate area is limited and miniaturization of the power conversion device 1 is required, this is extremely effective.

[0103] In particular, in the present invention, a control device 6 for controlling the secondary voltage V which is the charging voltage of the capacitor C is provided, and this control device 6 controls the secondary voltage V dc2 to the secondary voltage command value V dc2 by flowing a zero-phase voltage command value v dc2 ref which is the secondary side DC link current required for control. Since it has a secondary voltage control system 23 that generates z ref modeling of the secondary voltage V dc2 and design of the control system become possible, and the secondary voltage V dc2It becomes possible to design for responsiveness and perform stable secondary-side voltage control and drive control of the motor M.

[0104] Furthermore, in the embodiment, the secondary-side voltage control system 23 includes a secondary-side voltage control unit 27 that generates a zero-phase current command value i dc2 which is the secondary-side DC link current command value necessary for controlling the secondary-side voltage V z ref , a secondary-side DC link current control unit 28 that controls the zero-phase current i z (secondary-side DC link current) to the zero-phase current command value i z ref (secondary-side DC link current command value), and generates a primary-side output voltage command value v z ref for switching the primary-side inverter INV1 based on the zero-phase voltage command value v z ref , v u1 ref , v v1 ref , v w1 ref , and a secondary-side output voltage command value v u2 ref , v v2 ref , v w2 ref for switching the secondary-side inverter INV2. With such a configuration, more stable secondary-side voltage control and drive control of the motor M can be performed.

[0105] Also, in the embodiment, the output voltage command generation unit 29 adds the zero-phase voltage command value v real to the effective voltage V imag as the primary-side output voltage vector command value and / or the reactive voltage V z ref as the secondary-side output voltage vector command value to obtain the primary-side output voltage command value v u1 ref , v v1 ref , v w1 ref and the secondary-side output voltage command value v u2 ref, v v2 ref , v w2 ref has generated, and in a further embodiment, the output voltage command generation unit 29 is provided with the effective voltage V real (primary side output voltage vector command value) and the reactive voltage V imag (secondary side output voltage vector command value) is provided with a zero-phase voltage distribution unit 39 that distributes the zero-phase voltage command value v z ref , and the zero-phase voltage distribution unit 39 has a case where the gain M1 distributed to the effective voltage V real (primary side output voltage vector command value) is 1 and the gain M2 distributed to the reactive voltage V imag (secondary side output voltage vector command value) is 0, and the zero-phase voltage distribution unit 39 has a case where the gain M1 distributed to the effective voltage V real (primary side output voltage vector command value) is 0 and the gain M2 distributed to the reactive voltage V imag (secondary side output voltage vector command value) is 1, so the degree of freedom of control is increased.

[0106] real In this case, by setting the gain M1 distributed to the effective voltage V imag (primary side output voltage vector command value) to 1 and the gain M2 distributed to the reactive voltage V z ref (secondary side output voltage vector command value) to 0, the zero-phase voltage command value v

[0107] is borne by the primary side inverter INV1 with a higher voltage, and the operation range can be ensured. z Also, in the embodiment, the secondary side DC link current control unit 28 generates the zero-phase voltage command value v z ref so as to control the zero-phase current i z ref to the zero-phase current command value i z , so that the runaway of the zero-phase current i

[0108] can be prevented by feedback control. Incidentally, in the embodiment, the zero-phase current i z is used as an index indicating the secondary side DC link current.Although [a certain method] is adopted, in the inventions of claim 1 and claim 2, it is not limited thereto, and the capacitor current may be adopted as the secondary side DC link current. However, when the capacitor current is adopted, a sensor for detecting the current flowing through the capacitor C is separately required. But if it is the zero-phase current i z then, for each phase current i u , i v , i w from i z = (i u + i v + i w ) / 3, the control device 6 can detect it.

[0109] Also, in the embodiment, the secondary side DC link current control unit 28 is provided in the secondary side voltage control system 23. However, the inventions of claim 1 to claim 3 are also effective for a power conversion device without the secondary side DC link current control unit 28.

[0110] Furthermore, in the embodiment, the output voltage command generation unit 29 is configured to separately generate the effective voltage V real and the reactive voltage V imag as the primary side output voltage vector command value and the secondary side output voltage vector command value. However, in the inventions of claim 1 to claim 9, it is not limited thereto, and the method for determining the primary side output voltage vector command value and the secondary side output voltage vector command value can be variously changed. That is, as one of the methods for determining the primary side output voltage vector command value and the secondary side output voltage vector command value before adding the zero-phase voltage command value v z ref , there is a method of dividing into the effective voltage V real and the reactive voltage V imag .

[0111] Furthermore, in the embodiment, the switching element is described as being composed of IGBT, but MOSFET may also be used. In particular, the specific configurations and numerical values shown in the embodiment are not limited thereto and can be changed without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0112] 1 Power conversion device 2 DC power supply 3A~3F, 4A~4F Switching elements 6 Control device 7U, 7V, 7W windings 11 Positive power line 12 Negative power line 21 Speed control unit 22 dq-axis current control unit 23 Secondary voltage control system 24 Primary modulation unit 26 Secondary modulation unit 27 Secondary voltage control unit 28 Secondary DC link current control unit 29 Output voltage command generation unit 36 Active-inactive decomposition unit 39 Zero-phase voltage distribution unit C capacitor INV1 Primary inverter INV2 Secondary inverter M motor

Claims

1. A power conversion device including a primary-side inverter connected to one end of a winding having an open-end structure of a motor and a secondary-side inverter connected to the other end of the winding, and applying a differential voltage between the primary-side inverter and the secondary-side inverter to the motor, wherein the primary-side inverter is connected to a DC power supply, the secondary-side inverter is connected to a capacitor, negative power supply lines of the primary-side inverter and the secondary-side inverter are shared, and a control device for controlling a secondary-side voltage which is a charging voltage of the capacitor is provided, the control device has a secondary-side voltage control system that generates a zero-phase voltage command value for flowing a secondary-side DC link current necessary for controlling the secondary-side voltage to a secondary-side voltage command value, characterized in that the power conversion device.

2. The primary-side inverter and the secondary-side inverter are each composed of a plurality of switching elements, a positive input terminal of the primary-side inverter is connected to a positive power supply line of the DC power supply, a negative input terminal of the primary-side inverter is connected to the negative power supply line of the DC power supply, and an output terminal of the primary-side inverter is connected to one end of the winding, an output terminal of the secondary-side inverter is connected to the other end of the winding, and the capacitor is connected between a positive input terminal and a negative input terminal of the secondary-side inverter, the positive input terminal of the secondary-side inverter is not connected to the positive power supply line of the DC power supply, and the negative input terminal of the secondary-side inverter is connected to the negative power supply line of the DC power supply, and by switching each of the switching elements by the control device, an AC output is generated from the DC power supply, characterized in that the power conversion device according to claim 1.

3. The control device employs a capacitor current flowing through the capacitor as the secondary-side DC link current, or employs a zero-phase current as an index indicating the secondary-side DC link current, characterized in that the power conversion device according to claim 1.

4. The secondary-side voltage control system has a secondary-side voltage control unit that generates a secondary-side DC link current command value necessary for controlling the secondary-side voltage, and a secondary-side DC link current control unit that generates the zero-phase voltage command value for controlling the secondary-side DC link current to the secondary-side DC link current command value, An output voltage command generation unit that generates a primary-side output voltage command value for switching the primary-side inverter and a secondary-side output voltage command value for switching the secondary-side inverter based on the zero-phase voltage command value; The power conversion device according to claim 1, characterized by comprising the above.

5. The control device adopts the zero-phase current as an index indicating the secondary-side DC link current, and The secondary-side voltage control unit generates a zero-phase current command value based on the secondary-side voltage command value, The secondary-side DC link current control unit generates the zero-phase voltage command value based on the zero-phase current command value, The output voltage command generation unit generates a primary-side output voltage vector command value and a secondary-side output voltage vector command value from the dq-axis voltage command value, generates the primary-side output voltage command value from the primary-side output voltage vector command value, and generates the secondary-side output voltage command value from the secondary-side output voltage vector command value. The power conversion device according to claim 4, characterized by the above.

6. The power conversion device according to claim 5, characterized in that the output voltage command generation unit generates the primary-side output voltage command value and the secondary-side output voltage command value by adding the zero-phase voltage command value to the primary-side output voltage vector command value and / or the secondary-side output voltage vector command value.

7. The power conversion device according to claim 6, characterized in that the output voltage command generation unit includes a zero-phase voltage distribution unit that distributes the zero-phase voltage command value to the primary-side output voltage vector command value and the secondary-side output voltage vector command value.

8. The zero-phase voltage distribution unit has a case where the gain M distributed to the primary-side output voltage vector command value is 1 and the gain M distributed to the secondary-side output voltage vector command value is 0. 1 The power conversion device according to claim 7, characterized in that it has such a case. 2 where the gain M distributed to the secondary-side output voltage vector command value is 0.

9. The zero-phase voltage distribution unit has a gain M to be distributed to the primary-side output voltage vector command value 1 set to 0 and a gain M to be distributed to the secondary-side output voltage vector command value 2 set to 1. The power conversion device according to claim 7, characterized in that it has such a case.

10. The output voltage command generation unit decomposes the dq-axis voltage command value into an active voltage as the primary-side output voltage vector command value and a reactive voltage as the secondary-side output voltage vector command value, generates the primary-side output voltage command value from the active voltage, and generates the secondary-side output voltage command value from the reactive voltage. The power conversion device according to claim 5, characterized by the above.

11. The power conversion device according to claim 10, characterized in that the output voltage command generation unit generates the primary-side output voltage command value and the secondary-side output voltage command value by adding the zero-phase voltage command value to the active voltage and / or the reactive voltage.

12. The power conversion device according to claim 11, characterized in that the output voltage command generation unit includes a zero-phase voltage distribution unit that distributes the zero-phase voltage command value to the active voltage and the reactive voltage.

13. The zero-phase voltage distribution unit has a gain M for distribution to the active voltage 1 set to 1 and a gain M for distribution to the reactive voltage 2 set to 0. The power conversion device according to claim 12, characterized in that it has such a case.

14. The zero-phase voltage distribution unit has a gain M for distribution to the active voltage 1 set to 0 and a gain M for distribution to the reactive voltage 2 set to 1, and the power conversion device according to claim 12 is characterized by this.

15. The secondary-side DC link current control unit generates the zero-phase voltage command value so as to control the zero-phase current to the zero-phase current command value, and the power conversion device according to any one of Claims 5 to 14.

Images