JP2024034847A - Power conversion device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device with which it is possible to reduce noise currents due to switching control.

SOLUTION: A power conversion device 10 includes a control unit 70 that exercises power transmission control for flowing a current between a first power storage unit 21 and a second power storage unit 22 via a connection path 60 by switching switches QUH, QVH, QWH, QUL, QVL, QWL that are provided for each phase in an inverter 30. In power transmission control, the control unit 70 ensures that a time difference between timing when a switching state of switches in one phase is changed from on to off and timing when a switching state of switches in one of the remaining other phases is changed from off to on fits within a prescribed period that is 1/2 of one switching cycle of switches or less.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a power conversion device and a program.

BACKGROUND ART Conventionally, as described in Patent Document 1, a power conversion device that raises the temperature of a storage battery is known. The power conversion device described in Patent Document 1 connects a neutral point between two storage batteries and a neutral point of a winding of a rotating electric machine, and performs switching of an inverter so that ripple current flows between the two storage batteries. Take control. As a result, reactive power is exchanged between the two storage batteries, and the temperature of the storage batteries is increased.

International Publication No. 2020/153313

In the power conversion device described in Patent Document 1, in controlling the temperature of the storage battery, three-phase gate signals are synchronized when performing switching control of the inverter to flow current to the neutral point of the storage battery. In this case, the switching states of the switches in the three phases are synchronized, which increases the noise current and increases the fluctuation of the common mode voltage. As a result, harmonic components of the common mode current flowing to the ground and the current flowing to the neutral point become large. A possible countermeasure to this problem is to increase the size of the filter circuit, but this would result in an increase in the size of the power converter. Note that such a problem is not limited to temperature increase control of a storage battery, and can similarly occur in any power conversion device in which switching control of an inverter is performed to flow a current between two power storage units.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power conversion device and a program that can reduce noise current accompanying switching control.

The present invention
A rotating electrical machine having star-connected windings;
an inverter electrically connected to the winding and having a plurality of phases;
a connection path that electrically connects the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit to a neutral point of the winding in a first power storage unit and a second power storage unit that are connected in series; In a power conversion device comprising:
a control unit that performs power transfer control to flow a current between the first power storage unit and the second power storage unit via the connection path by switching a switch provided for each phase in the inverter;
In the power transfer control, the control unit determines a timing for switching the switching state of the switch in one of the phases from on to off, and a timing for switching the switching state of the switch in any one of the remaining phases to off. It is characterized in that the time difference between the switching timing and the timing of switching on is kept within a predetermined period of 1/2 or less of one switching cycle of the switch.

In the conventional technology, three phases switch simultaneously, but according to the above configuration, the noise current that changes as the switching state of the switch in any one phase is switched from on to off is transferred to one of the remaining phases. This is suppressed by the noise current that changes as the switching state of the switch in one phase is changed from off to on. This makes it possible to reduce noise current associated with switching control.

The present invention
A rotating electric machine having windings;
A power conversion device comprising an inverter having a switch provided for each phase and electrically connecting the winding and a power storage unit,
An external charger can be connected to the winding and the negative terminal of the power storage unit,
In a state where the winding and the negative terminal of the power storage unit are connected to the charger, the timing of switching the switching state of the switch in one of the phases from on to off, and any of the remaining ones. The present invention is characterized by comprising a control unit that keeps the time difference between the timing of switching the switching state of the switch from off to on in one phase within a predetermined period of 1/2 or less of one switching cycle of the switch.

In the conventional technology, three phases switch simultaneously, but according to the above configuration, the noise current that changes as the switching state of the switch in any one phase is switched from on to off is transferred to one of the remaining phases. This is suppressed by the noise current that changes as the switching state of the switch in one phase is changed from off to on. This makes it possible to reduce noise current associated with switching control.

The present invention
A rotating electrical machine having star-connected windings;
an inverter electrically connected to the winding and having a plurality of phases;
a connection path that electrically connects the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit to a neutral point of the winding in a first power storage unit and a second power storage unit that are connected in series;
a control unit that performs power transfer control to flow a current between the first power storage unit and the second power storage unit via the connection path by switching a switch provided for each phase in the inverter; applied to a power converter equipped with
In the control section,
In the power transfer control, a timing for switching the switching state of the switch in any one of the phases from on to off, and a timing for switching the switching state of the switch in any one of the remaining phases from off to on. The time difference between the switch and the switch is kept within a predetermined period of 1/2 or less of one switching cycle of the switch.

In the conventional technology, three phases switch simultaneously, but according to the above configuration, the noise current that changes as the switching state of the switch in any one phase is switched from on to off is transferred to one of the remaining phases. This is suppressed by the noise current that changes as the switching state of the switch in one phase is changed from off to on. This makes it possible to reduce noise current associated with switching control.

The present invention
A rotating electric machine having windings;
Applied to a power converter device including an inverter having a switch provided for each phase and electrically connecting the winding and the power storage unit,
An external charger can be connected to the winding and the negative terminal of the power storage unit,
In the control section,
In a state in which the winding and the negative terminal of the power storage unit are connected to the charger, the timing of switching the switching state of the switch in one of the phases from on to off, and any of the remaining ones. The time difference between the timing at which the switching state of the switch in one phase is switched from off to on is kept within a predetermined period of 1/2 or less of one switching cycle of the switch.

In the conventional technology, three phases switch simultaneously, but according to the above configuration, the noise current that changes as the switching state of the switch in any one phase is switched from on to off is transferred to one of the remaining phases. This is suppressed by the noise current that changes as the switching state of the switch in one phase is changed from off to on. This makes it possible to reduce noise current associated with switching control.

FIG. 1 is a configuration diagram of a power conversion device according to a first embodiment. FIG. 1 is a block diagram of a control device according to a first embodiment. FIG. 3 is a diagram illustrating timing of switching on and off of a switching state. FIG. 3 is a diagram illustrating the timing of switching on and off a switching state. A graph showing the relationship between frequency and common mode current. Graph showing fluctuations in neutral point current. FIG. 3 is a diagram illustrating timing of switching on and off of a switching state. FIG. 3 is a block diagram of a control device according to a second embodiment. A diagram explaining space vector modulation. FIG. 3 is a diagram illustrating timing of switching on and off of a switching state. FIG. 3 is a configuration diagram of a power conversion device according to another embodiment. FIG. 3 is a configuration diagram of a power conversion device according to another embodiment. FIG. 3 is a configuration diagram of a power conversion device according to another embodiment.

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals and the description thereof will be omitted.

(First embodiment)
With reference to FIG. 1, a configuration example of a power conversion device 10 according to a first embodiment will be described. As shown in FIG. 1, the power conversion device 10 includes an inverter 30, a rotating electrical machine 40, a monitoring unit 50, a connection path 60, a connection switch 61, a phase current sensor 62, and a neutral point current sensor 63. , and a control device 70. The rotating electric machine 40 is a three-phase synchronous machine, and includes U, V, and W phase windings 41U, 41V, and 41W connected in a star shape as stator windings. The phase windings 41U, 41V, and 41W are arranged to be shifted by 120 degrees in electrical angle. The rotating electric machine 40 is, for example, a permanent magnet synchronous machine. The power conversion device 10 is installed in, for example, an electric vehicle, a hybrid vehicle, or the like. When the power conversion device 10 is installed in an electric vehicle, a hybrid vehicle, or the like, the rotating electric machine 40 is a main engine mounted on the vehicle and serves as a driving power source for the vehicle.

The inverter 30 has three phases connected in series, including U, V, W phase upper arm switches QUH, QVH, QWH and U, V, W phase lower arm switches QUL, QVL, QWL. In this embodiment, voltage-controlled semiconductor switching elements are used as the switches QUH, QVH, QWH, QUL, QVL, and QWL, and specifically, IGBTs are used. Therefore, the high potential side terminal of each switch QUH, QVH, QWH, QUL, QVL, QWL is a collector, and the low potential side terminal is an emitter. Diodes DUH, DVH, DWH, DUL, DVL, and DWL as freewheel diodes are connected in antiparallel to each switch QUH, QVH, QWH, QUL, QVL, and QWL.

A first end of a U-phase winding 41U is connected to the emitter of the U-phase upper arm switch QUH and the collector of the U-phase lower arm switch QUL via a U-phase conductive member 32U such as a bus bar. A first end of a V-phase winding 41V is connected to the emitter of the V-phase upper arm switch QVH and the collector of the V-phase lower arm switch QVL via a V-phase conductive member 32V such as a bus bar. A first end of a W-phase winding 41W is connected to the emitter of the W-phase upper arm switch QWH and the collector of the W-phase lower arm switch QWL via a W-phase conductive member 32W such as a bus bar. The second ends of the U, V, and W phase windings 41U, 41V, and 41W are connected at a neutral point O.

The collectors of the upper arm switches QUH, QVH, QWH and the positive terminal of the battery pack 20 are connected by a positive bus Lp such as a bus bar. The emitters of the lower arm switches QUL, QVL, QWL and the negative terminal of the assembled battery 20 are connected by a negative bus Ln such as a bus bar.

The inverter 30 includes a capacitor 31 that connects the positive bus Lp and the negative bus Ln. In this embodiment, the capacitor 31 will be described as being built into the inverter 30, but the capacitor 31 is not limited to this. For example, capacitor 31 may be provided outside inverter 30.

As shown in FIG. 1, the assembled battery 20 is configured as a series connection of battery cells as single cells, and has a terminal voltage of, for example, several hundred volts. In this embodiment, the terminal voltages (for example, rated voltages) of each battery cell that constitute the assembled battery 20 are set to be the same. As the battery cell, for example, a secondary battery such as a lithium ion battery can be used. In this embodiment, the assembled battery 20 will be described as being provided outside the power conversion device 10, but the present invention is not limited thereto. For example, the assembled battery 20 may be configured to be integrated with the power conversion device 10.

Among the battery cells constituting the assembled battery 20, a series connection of a plurality of battery cells on the high potential side constitutes the first storage battery 21, and a series connection of a plurality of battery cells on the low potential side constitutes the second storage battery 22. It consists of That is, the assembled battery 20 is divided into two blocks. In this embodiment, the number of battery cells that make up the first storage battery 21 and the number of battery cells that make up the second storage battery 22 are the same. Therefore, the terminal voltage (for example, rated voltage) of the first storage battery 21 and the terminal voltage (for example, rated voltage) of the second storage battery 22 are the same. Note that the first storage battery 21 corresponds to a "first power storage unit" and the second storage battery 22 corresponds to a "second power storage unit".

In the assembled battery 20, an intermediate terminal B is connected to the negative terminal of the first storage battery 21 and the positive terminal of the second storage battery 22.

The monitoring unit 50 monitors the terminal voltage, temperature, etc. of each battery cell that constitutes the assembled battery 20. The monitoring unit 50 is configured to be able to communicate with the control device 70, and outputs data such as terminal voltage and temperature to the control device 70 in accordance with commands from the control device 70.

The connection path 60 electrically connects the intermediate terminal B and the neutral point O of the assembled battery 20. The connection switch 61 is provided on the connection path 60. In this embodiment, a relay is used as the connection switch 61. By turning on the connection switch 61, the intermediate terminal B and the neutral point O are electrically connected. On the other hand, by turning off the connection switch 61, the connection between the intermediate terminal B and the neutral point O is electrically interrupted.

The phase current sensor 62 detects each phase current Iu, Iv, and Iw flowing through each conductive member 32U to 32W. Neutral point current sensor 63 detects the current flowing to neutral point O (hereinafter referred to as neutral point current). The detected values of the phase current sensor 62 and the neutral point current sensor 63 are input to the control device 70.

The control device 70 is configured as a microcomputer including a CPU, ROM, RAM, input/output ports for inputting/outputting various signals, and the like. The control device 70 performs switching control of each switch constituting the inverter 30 in order to feedback control the control amount of the rotating electric machine 40 to its command value. The controlled amount is, for example, torque. In each phase, the upper and lower arm switches are turned on alternately. Note that the control device 70 corresponds to a "control unit".

Further, the control device 70 controls the neutral point current by turning on and off the connection switch 61, and increases the temperature of the assembled battery 20. One of the reasons for raising the temperature of the battery pack 20 is that the performance of the battery pack 20 may deteriorate at low temperatures.

Here, an example of a method for increasing the temperature of the assembled battery 20 will be explained. The control device 70 compares the current temperature of the assembled battery 20 obtained from the monitoring unit 50 and the target temperature. When the current temperature is less than the target temperature, the control device 70 turns on the connection switch 61. Thereby, the intermediate terminal B and the neutral point O are electrically connected via the connection path 60. Subsequently, the control device 70 performs power transfer control to increase the temperature of the assembled battery 20. In power transfer control, switching control of each switch QUH to QWL is performed. As a result, current flows between the first storage battery 21 and the second storage battery 22 via the inverter 30, each phase winding 41U, 41V, 41W, and the connection path 60, and the current flows between the first storage battery 21 and the second storage battery 22. The temperature rises.

Next, details of the control device 70 will be explained with reference to FIG. 2. FIG. 2 is a block diagram showing the functional configuration of the control device 70.

As shown in FIG. 2, the control device 70 includes PI control sections 71 and 74, a conversion section 72, and a signal control section 73 as its functional configuration.

The control device 70 subtracts the d-axis current id and the q-axis current iq flowing through the rotating electric machine 40 from the d-axis current command value id* and the q-axis current command value iq* based on the torque command value, respectively. The deviation is calculated and the calculated deviation is output to the PI control unit 71.

The PI control unit 71 generates a d-axis voltage command value Vd and a q-axis voltage command value Vq using PI control so that the input deviation is eliminated, and outputs them to the conversion unit 72.

The conversion unit 72 coordinates converts the d-axis voltage command value Vd and the q-axis voltage command value Vq to generate three-phase voltage command values Vu*, Vv*, Vw*, and transmits the generated command values to the signal control unit. 73. Note that Vu* is a U-phase voltage command value, Vv* is a V-phase voltage command value, and Vw* is a W-phase voltage command value.

The control device 70 calculates the deviation between the neutral point current command value IMG* and the neutral point current IMG flowing through the rotating electrical machine 40, and outputs the calculated deviation to the PI control unit 74. The PI control unit 74 generates a neutral point voltage command value V0 using PI control so that the input deviation is eliminated, and outputs the generated command value to the signal control unit 73.

The signal control unit 73 generates a carrier, uses the generated carrier to pulse width modulate the three-phase voltage command values Vu*, Vv*, Vw*, and generates a gate signal for controlling the operation of the inverter 30. do. The carrier of this embodiment is a triangular wave signal with equal gradual increase rate and gradual decrease rate. The signal control unit 73 generates pulsed voltages for each of the U-phase, V-phase, and W-phase based on the comparison result between the three-phase voltage command values Vu*, Vv*, and Vw* and the carrier. . The signal control unit 73 generates pulsed gate signals for the switches of each phase of the inverter 30 based on the generated pulsed voltage.

As already mentioned, in the prior art, three-phase gate signals are synchronized when controlling the neutral point current. This increases the noise current and increases the fluctuation of the common mode voltage. The inventors determined the timing of switching the switching state of the switch in any one of the U-phase, V-phase, and W-phase from on to off, and the timing of switching the switching state of the switch in any one of the remaining phases from off to on. It has been found that by synchronizing the switching timing with the switching timing, fluctuations in the common mode voltage can be reduced. Details will be explained with reference to FIG. 3.

FIG. 3A is a diagram illustrating on/off switching states of each phase and fluctuations in common mode voltage according to a comparative example. Tsw in FIG. 3 indicates one switching period of the switch. As shown in FIG. 3A, in the comparative example, the switching state of each phase is switched on and off between times T11 and T16, and the common mode voltage varies from 1/2 Vdc to -1/2 Vdc. In contrast, in the present embodiment, the timing of switching the switching state of the switch in any one phase from on to off is synchronized with the timing of switching the switching state of the switch in any one of the remaining phases from off to on. . Details will be described below with reference to FIG. 3(B).

First, the signal control unit 73 sets the phase having the largest absolute value of the voltage command value among the three-phase voltage command values Vu*, Vv*, and Vw* as the reference phase. Here, as an example, the U phase is assumed to be the reference phase. Next, the signal control unit 73 sets the phase having the next largest absolute value of the voltage command value among the three-phase voltage command values Vu*, Vv*, and Vw* as an inverted phase for cancellation. Here, as an example, the W phase is assumed to be an inverted phase. Next, the signal control unit 73 makes the absolute value of the voltage command value of the inverted phase equal to the absolute value of the voltage command value of the reference phase.

Next, the signal control unit 73 generates a carrier 81 by inverting the carrier 80 with respect to the reference phase. Inverting the carriers here means controlling the carriers to have opposite phases. Therefore, the phase difference between carrier 80 and carrier 81 in FIG. 3(B) is 180 degrees. The cycles of carrier 80 and carrier 81 are the same. The signal control unit 73 compares the reference phase and the V phase with the carrier 80, and performs switching control of the switches in the reference phase and the V phase based on the comparison result. On the other hand, the signal control unit 73 performs a comparison with the carrier 81 for the inverted phase, and performs switching control of the switch in the inverted phase based on the comparison result. Carrier 80 corresponds to the first carrier, and carrier 81 corresponds to the second carrier.

At time T22 in FIG. 3B, the U-phase voltage command value Vu* becomes smaller than the carrier 80, and the signal control unit 73 switches the switching state of the switch QUH in the U phase from on to off. On the other hand, at time T22, the W-phase voltage command value Vw* becomes larger than the carrier 81, and the signal control unit 73 switches the switching state of the switch QWH in the W-phase from off to on. Similarly, at time T23, the U-phase voltage command value Vu* becomes larger than the carrier 80, and the signal control unit 73 switches the switching state of the switch QUH in the U phase from off to on. Further, at time T23, the W-phase voltage command value Vw* becomes smaller than the carrier 81, and the signal control unit 73 switches the switching state of the switch QWH in the W-phase from on to off.

In this way, for the W phase, which is an inverted phase, by comparing the carrier 80 with the inverted carrier 81, the timing for switching the switching state of the switch QUH from on to off in the U phase and the timing in the W phase can be determined. It becomes possible to synchronize the timing of switching the switching state of the switch QWH from off to on. Similarly, it is possible to synchronize the timing at which the switching state of the switch QUH in the U phase is switched from off to on and the timing at which the switching state of the switch QWH in the W phase is switched from on to off.

Due to this synchronization, the noise current that changes as the switching state of the switch QUH in the U phase is changed from on to off is changed from the noise current that changes as the switching state of the switch QWH in the W phase is changed from off to on. suppressed by Similarly, the noise current that changes as the switching state of the switch QUH in the U phase is changed from off to on is caused by the noise current that changes as the switching state of the switch QWH in the W phase is changed from on to off. suppressed. This makes it possible to reduce fluctuations in common mode voltage. Specifically, between times T21 and T24 in FIG. 3(B), the common mode voltage fluctuates from 1/6 Vdc to -1/6 Vdc, and from the comparative example in FIG. 3(A), the common mode voltage It can be seen that the fluctuation of is reduced.

Furthermore, in order to control the neutral point current, the control device 70 causes the neutral point voltage command value V0 for performing power transfer control to be reflected in the voltage command values for phases other than the reference phase and the inverted phase. In this embodiment, the phases other than the reference phase and the inversion phase are the V phase. That is, for the V-phase, the control device 70 causes the neutral point voltage command value V0 to be reflected in the V-phase voltage command value Vv*. An example of reflection is addition.

According to the first embodiment described in detail above, the following effects can be obtained.

The control device 70 determines the timing for changing the switching state of a switch in any one of the U-phase, V-phase, and W-phase from on to off, and changing the switching state of a switch in any one of the remaining phases from off to on. synchronize the timing of switching to Specifically, the control device 70 selects a reference phase (eg, U phase) and an inverted phase (eg, W phase) based on the absolute value of the voltage command value. The control device 70 compares the reference phase with the carrier 80, and compares the inverted phase with the carrier 81 obtained by inverting the carrier 80. That is, the control device 70 controls the carrier 81 so that the carrier 81 has an opposite phase to the carrier 80 and performs the comparison. Thereby, the control device 70 synchronizes the timing of switching the switching state of the switch in any one phase from on to off and the timing of switching the switching state of the switch in any one of the remaining phases from off to on. becomes possible.

As a result, as shown in FIG. 4, three phases are switched simultaneously in the comparative example, whereas in the present embodiment, the timing for switching the switching state of the switch in any one phase from on to off and the timing to switch the switching state of the switch in any one phase from on to off are determined. The timing of switching the switching state of the switches in the phase from off to on is synchronized. With this synchronization, the noise current that changes due to switching the switching state of the switch in any one phase from on to off can be caused by changing the switching state of the switch in any one of the remaining phases from off to on. It is suppressed by the noise current that changes accordingly. This makes it possible to reduce noise current associated with switching control and to reduce fluctuations in common mode voltage. By reducing fluctuations in common mode voltage, common mode current can also be reduced. Specifically, as shown in FIG. 5, in the range from 100 kHz to 1 MHz, it is possible to significantly attenuate the common mode current (for example, by 6 dB or more) compared to the comparative example.

Further, the control device 70 adds the neutral point voltage command value V0 to the voltage command value for the winding in a switch different from the switch to be synchronized (for example, V phase) among the switches of each phase, and performs power transfer control. conduct. This makes it possible to reduce fluctuations in common mode voltage and control neutral point current at the same time.

Further, the control device 70 controls the neutral point current flowing between the first storage battery 21 and the second storage battery 22 via the connection path 60 in order to increase the temperature of the assembled battery 20. At this time, it can be confirmed that by reducing the fluctuation of the common mode voltage, the harmonic components of the neutral point current are reduced compared to the comparative example, as shown in FIG. By reducing harmonic components, it is possible to reduce the number of filter capacitors required at the neutral point. In addition, in this embodiment, it is assumed that control for reducing fluctuations in the common mode voltage is performed during temperature increase control of the assembled battery 20; however, the present invention is not limited to this, and the first storage battery during charging or driving It can also be applied to the case of power transfer between 21 and the second storage battery 22.

In the example shown in FIG. 3, the timing of switching the switching state of the switch QUH from on to off in the U phase is synchronized with the timing of switching the switching state of the switch QWH in the W phase from off to on, and The timing of switching the switching state of the switch QUH from off to on and the timing of switching the switching state of the switch QWH in the W phase from on to off were synchronized. However, it is not always necessary to synchronize both, and the same effect can be achieved even when either one is synchronized.

(Modified example)
Next, a modification of the first embodiment will be described with reference to FIG. 7.

In the first embodiment, as a method of synchronizing the timing of switching the switching state of a switch in any one phase from on to off and the timing of switching the switching state of a switch in any one of the remaining phases from off to on, Explained how to flip your career. In the modified example, other methods will be explained.

First, the signal control unit 73 sets the phase having the largest absolute value of the voltage command value among the three-phase voltage command values Vu*, Vv*, and Vw* as the reference phase. Here, as an example, the U phase is assumed to be the reference phase. Next, the signal control unit 73 sets the phase having the next largest absolute value of the voltage command value as an inversion phase for cancellation. Here, as an example, the W phase is assumed to be an inverted phase. Next, the signal control unit 73 makes the absolute value of the voltage command value of the inverted phase equal to the absolute value of the voltage command value of the reference phase. The processing up to this point is the same as in the first embodiment.

Next, the signal control unit 73 inverts the sign of the voltage command value of the inverted phase. As a result, as shown in FIG. 7, the W-phase voltage command value Vw* has the same magnitude and the same sign as the U-phase voltage command value Vu*. Next, the signal control unit 73 compares the voltage command value and the carrier 80 for each phase. At this time, the signal control unit 73 inverts the positive/negative logic at the time of carrier comparison for the W-phase voltage command value Vw*. Here, in comparing the voltage command value and the carrier, positive logic is defined as the voltage command value becoming smaller than the carrier and switching the switching state from on to off, and the voltage command value becoming smaller than the carrier and switching the switching state from on to off. Switching from off to on is defined as negative logic.

In a modified example, the signal control unit 73 uses positive logic for the U phase and uses negative logic, which is an inversion of the positive logic, for the W phase. That is, at time T22 in FIG. 7, the U-phase voltage command value Vu* becomes smaller than the carrier 80, and the signal control unit 73 switches the switching state of the switch QUH in the U phase from on to off. On the other hand, when comparing W-phase carriers, negative logic, which is an inversion of positive logic, is used. That is, at time T22, the W-phase voltage command value Vw* becomes smaller than the carrier 80, and the signal control unit 73 switches the switching state of the switch QWH in the W-phase from off to on. Similarly, at time T23, the U-phase voltage command value Vu* becomes larger than the carrier 80, and the signal control unit 73 switches the switching state of the switch QUH in the U phase from off to on. At time T23, the W-phase voltage command value Vw* becomes larger than the carrier 80, and the signal control unit 73 switches the switching state of the switch QWH in the W-phase from on to off. Note that this control reverses the switching state of the switch based on the magnitude comparison between the voltage command value and the carrier 80 in the inversion phase with respect to the switching state of the switch based on the magnitude comparison between the voltage command value and the carrier 80 in the reference phase. It may also be expressed as causing.

Even with this method, as shown in FIG. 7, as in the first embodiment, the timing of switching the switching state of switch QUH from on to off in the U phase and the switching state of switch QWH in the W phase are changed. It becomes possible to synchronize the timing of switching from to on. Further, it is possible to synchronize the timing of switching the switching state of the switch QUH in the U phase from off to on and the timing of switching the switching state of the switch QWH in the W phase from on to off. Regarding the effects, the same effects as in the first embodiment can be obtained. Note that, similarly to the first embodiment, the neutral point voltage command value V0 for controlling the neutral point current for the V phase is added to the V phase voltage command value Vv*.

(Second embodiment)
Next, a second embodiment will be described with reference to FIGS. 8 to 10. The second embodiment differs from the first embodiment in that space vector modulation is used to generate the switching pattern. For configurations that overlap with those of the first embodiment, reference numerals will be cited and explanations thereof will be omitted. The differences will be mainly explained below.

FIG. 8 is a block diagram showing the functional configuration of the control device 70, similar to FIG. 2. The conversion unit 72 shown in FIG. 8 coordinately transforms the d-axis voltage command value Vd and the q-axis voltage command value Vq to generate a voltage command value Vα and a voltage command value Vβ in the αβ coordinate system, and converts the generated command value is output to the space vector control section 75.

Next, generation of a switching pattern using space vector modulation will be described with reference to FIG. In the case of a three-phase inverter, there are eight possible patterns for the on/off switching states of the switches that make up the inverter, so as shown in Figure 9, six fundamental vectors from V1 to V6 and zero vectors for V0 and V7 are used. have Subscripts (100), (110), etc. of each vector indicate the switching states of the upper and lower arm switches. Specifically, "1" indicates that the upper side of the arm is on and the lower side is off, and "0" indicates that the upper side of the arm is off and the lower side is on. That is, the subscript (100) of the V1 vector indicates that it is a vector in a switching state in which the upper side of the arm is connected to the U phase and the lower side of the arm is connected to the V and W phases.

The space vector diagram shown in FIG. 9 is defined by eight types of vectors, that is, basic vectors V1 to V6, which are effective voltage vectors, and zero vectors V0 and V7, which are reactive voltage vectors. The space vector control unit 75 controls the selection of these vectors V0 to V7 and their generation times.

First, the conversion unit 72A converts the d-axis voltage command value Vd and q-axis voltage command value Vq in the two-phase rotating coordinate (dq coordinate) system into the α-axis voltage command value Vα and β in the two-phase fixed coordinate (αβ coordinate) system. Convert to shaft voltage command value Vβ. The space vector control unit 75 generates a voltage command value vector Vref using the α-axis voltage command value Vα and the β-axis voltage command value Vβ. The α-axis component of the voltage command value vector Vref is the α-axis voltage command value Vα, and the β-axis component of the voltage command value vector Vref is the β-axis voltage command value Vβ. In the space vector modulation, the space vector is divided into six sectors by the first to sixth fundamental vectors V1 to V6, which have an angular difference of 60 electrical degrees. The voltage command value vector Vref is located at an angle between two basic vectors other than the zero vectors V0 and V7. In FIG. 9, the voltage command value vector Vref is located at an angle between the first and second basic vectors V1 and V2. The space vector control unit 75 selects two first and second basic vectors V1 and V2 adjacent to the voltage command value vector Vref, and controls the first and second basic vectors V1 and V2 based on the voltage command value vector Vref. Set the output time ratio.

Next, the space vector control unit 75 equally distributes the remaining time other than the output time of the first and second basic vectors V1 and V2 in one switching period Tsw to the third and sixth basic vectors V3 and V6. do. The third basic vector V3 is adjacent to the second basic vector V2 in the counterclockwise direction, and has an angular difference of 60 degrees from the second basic vector V2. The sixth basic vector V6 is adjacent to the first basic vector V1 in the clockwise direction, and has an angular difference of 60 degrees from the second basic vector V2. That is, the angular difference between the third fundamental vector V3 and the sixth fundamental vector V6 is 180 degrees. Generally, in space vector modulation, a time ratio equivalent to the voltage command value vector Vref is set using two basic vectors sandwiching the voltage command value vector Vref and one or two zero vectors, but in this embodiment Now, the time ratio is set using four basic vectors without using the zero vector so that the time ratio is equivalent to the voltage command value vector Vref. This eliminates the use of zero vectors V0 and V7, making it possible to reduce fluctuations in the common mode voltage.

Next, the space vector control unit 75 calculates the time ratios of the first to third and sixth basic vectors V1, V2, V3, and V6 using the zero-phase voltage command value vector V0ref based on the neutral point voltage command value V0. adjust. The neutral point voltage command value V0 may be used as the zero-phase voltage command value vector V0ref. The adjustment method is as follows. The space vector control unit 75 inverts the sign of the zero-phase voltage command value vector V0ref and adds it to the second and fourth basic vectors V2 and V4, and adds it to the first and third basic vectors V1 and V3. is added while maintaining the sign of the zero-phase voltage command value vector V0ref. At this time, the zero-phase voltage command value vector V0ref is added as is to the basic vector related to the voltage command value vector Vref so as not to affect the voltage vector of the αβ coordinate, and the zero-phase voltage command value vector V0ref is not related to the voltage command value vector Vref. 1/2 of the zero-phase voltage command value vector V0ref is added to the basic vector.

Specifically, as shown in FIG. 9, for the first fundamental vector V1, "+V0ref" indicated by 91 is added to the voltage vector indicated by 90. Regarding the second fundamental vector V2, "-V0ref" indicated by the symbol 93 is added to the voltage vector indicated by the symbol 91. Regarding the third basic vector V3, "+1/2V0ref" indicated by the symbol 95 is added to the voltage vector indicated by the symbol 94. Regarding the sixth basic vector V6, "-1/2V0ref" indicated by 97 is added to the voltage vector indicated by 96. Note that the lengths of voltage vectors indicated by symbols 90, 92, 94, and 96 correspond to time ratios. By these additions, the time ratio of the first and third basic vectors V1 and V3 increases, and the time ratio of the second and sixth basic vectors V2 and V6 decreases. Therefore, as shown in FIG. 9, the zero-phase voltage command value vector V0ref can have a value that is not zero in the direction of the zero vector V7 (minus direction). By adjusting the time ratio in this manner, in this embodiment, it becomes possible to control the zero-phase voltage command value vector V0ref without using the zero vectors V0 and V7.

Next, the space vector control unit 75 outputs the selected first to third and sixth fundamental vectors at least once in one switching period, so that the phase difference between two consecutive fundamental vectors is 120 degrees. Output the fundamental vector so that An example of the output order of the fundamental vectors will be described with reference to FIG. 9. First, the space vector control unit 75 outputs the first fundamental vector 1. Next, as shown at 85, the space vector control unit 75 outputs the third fundamental vector 3 having a phase difference of 120 degrees with respect to the first fundamental vector 1. Next, as shown at 86, the space vector control unit 75 outputs the second fundamental vector 2 adjacent to the third fundamental vector 3. Next, as shown at 87, the space vector control unit 75 outputs a sixth fundamental vector 6 having a phase difference of 120 degrees with respect to the second fundamental vector 2. In this example, there are two combinations in which the phase difference between two consecutive fundamental vectors is 120 degrees in a half period of one switching period Tsw.

FIG. 10 shows the on/off switching timing of the switching states of the switches according to this output order. FIG. 10 shows an example of the transition of the switching state in half of one switching period Tsw. As shown in FIG. 10, when transitioning from fundamental vector 1 to fundamental vector 3, the timing of switching the switching state of switch QUH in U phase from on to off and the switching state of switch QVH in V phase from off to on. It is possible to synchronize the timing. Similarly, when transitioning from basic vector 2 to basic vector 6, the timing to switch the switching state of switch QVH from on to off in the V phase and the timing to switch the switching state of switch QWH in the W phase from off to on are synchronized. It becomes possible to do so. This makes it possible to reduce the frequency at which noise current occurs due to switching control.

Although FIG. 10 shows the transition of the switching state in half of one switching period Tsw, the space vector control unit 75 changes the switching state in one switching period Tsw to, for example, V1→V3→V2→V6→V2→ The fundamental vectors can be output in the order of V3→V1. Further, as shown in FIG. 10, the output order of the fundamental vectors is not limited to the order of V1→V3→V2→V6 in half of one switching period Tsw, and the space vector control unit 75 outputs, for example, V1→V6→V2. It is also possible to output the fundamental vectors in the order of →V3.

Even when space vector modulation is used in this way, the timing of switching the switching state of the switch in any one phase from on to off, and the timing of switching the switching state of the switch in any one of the remaining phases from off to on. It becomes possible to synchronize the switching timing. According to the second embodiment, since zero vectors V0 and V7 are not used, fluctuations in common mode voltage can be reduced. Moreover, the neutral point current can be controlled while controlling the drive of the rotating electric machine 40.

In the example shown in FIG. 9, the case where the voltage command value vector Vref exists between the first and second basic vectors V1 and V2 has been described, but this also applies to the case where the voltage command value vector Vref exists in other sectors. The invention is applicable. For example, if the voltage command value vector Vref exists between the first and sixth basic vectors V1 and V6, the selected vectors are the two first and sixth basic vectors V1 and V6 adjacent to the voltage command value vector Vref, V6, and second and fifth fundamental vectors V2 and V5 having a phase difference of 60 degrees with respect to the first and sixth fundamental vectors, respectively. As for the order in which these fundamental vectors are output, it is sufficient to output them at least once in one switching period so that the phase difference between two consecutive fundamental vectors is 120 degrees, so for example, V1→V5→V6→ Examples include orders such as V2.

(Other embodiments)
In the above-described embodiment, the timing of switching the switching state of the switch in any one phase from on to off is synchronized with the timing of switching the switching state of the switch in any one of the remaining phases from off to on. However, it is not limited to this. Even if it is possible to perfectly match the on/off switching timing in a simulation or the like, in reality it is difficult to perfectly match the timing due to various factors. Therefore, there may be a time difference between the timing of switching the switching state of the switch in any one phase from on to off and the timing of switching the switching state of the switch in any one of the remaining phases from off to on. This time difference may be controlled so that it falls within a predetermined period. The predetermined period is a period of 1/2 or less of one switching period Tsw (for example, 2 μsec), for example, a period of 1/10 or less of one switching period Tsw or 1/20 or less of one switching period Tsw.

In the above-described embodiment, the phase difference between the carrier 80 and the carrier 81 was explained to be 180 degrees, but the present invention is not limited to this. Even if the phase difference is, for example, 179 degrees or 181 degrees, the same effect as described above can be obtained. This effect can be achieved. Therefore, the control device 70 may set the phase difference between the carriers 80 and 81 so that the time difference between the on/off switching timings is within a predetermined period.

Although it is difficult to perfectly match the on/off switching timing, it is possible to correct and reduce the deviation in the on/off switching timing due to dead time or the like (i.e., the time difference between the turn-on time and the turn-off time). An example of the correction method will be described below.

The turn-on time is expressed as the sum of the turn-on delay time and the on-to-off switching time. Further, the turn-off time is expressed as the sum of the turn-off delay time and the off-to-on switching time. The turn-on delay time is required to charge the input capacitance of each switch QUH, QVH, QWH, QUL, QVL, and QWL until the gate voltage of each switch QUH, QVH, QWH, QUL, QVL, and QWL rises to the threshold voltage. It's time. Moreover, the switching time from on to off is the time required until the output voltage falls. The turn-off delay time is the time required for the input capacitance of each switch QUH, QVH, QWH, QUL, QVL, and QWL to be discharged and for the gate voltage of each switch QUH, QVH, QWH, QUL, QVL, and QWL to fall. . The off-to-on switching time is the time required for the output voltage to rise.

Here, a case will be described in which there is a time difference between the U-phase turn-on time and the W-phase turn-off time. First, the control device 70 obtains the U-phase turn-on time based on the U-phase voltage, and obtains the W-phase turn-off time based on the W-phase voltage. Next, the control device 70 calculates an on-off time difference that is a time difference between the obtained turn-on time and turn-off time. The control device 70 sets a predetermined offset for reducing the on-off time difference to the voltage command value of either the U phase or the W phase based on the calculated on-off time difference, and corrects the shift in the on/off switching timing.

The offset to be set to the voltage command value will be explained. This offset is related to the carrier tilt. The career slope is calculated as follows. The half period of the carrier is the reciprocal of the switching frequency fsw divided by 1/2. The carrier amplitude is set from -1 to 1. Therefore, the slope of the carrier is ±4fsw. The sign is positive from the valley to the peak, and negative from the peak to the valley. An offset is added to the voltage command value by "4fsw x t", which is the slope 4fsw multiplied by the t correction. Thereby, it becomes possible to change the switching time by the amount of t correction, and it becomes possible to reduce the deviation in the on/off switching timing.

The t correction includes (1) dead time, (2) delay time until the switch actually starts to turn on or off based on the gate signal, and (3) on-off time due to charging and discharging of the parasitic capacitance Cds of the switch. This includes the time T required to switch from off to on or from off to on. In particular, regarding the time (3), on-time correction is possible by correcting according to the parasitic capacitance Cds, power supply voltage Vdc, and current I. When the time T is expressed mathematically, it becomes T=Cds×2×Vdc/I.

As shown in FIG. 11, the present invention provides a quick charger 88 (for example, 400V) that is a first external charger, or an ultra-fast charger 89 that is a second external charger that has a higher charging voltage than the quick charger 88. It is also applicable to the case where the assembled battery 20 is charged using (for example, 800V).

The present invention is also applicable to a case where a quick charger 88 is connected to the rotating electrical machine 40 and the assembled battery 20 is charged via the rotating electrical machine 40, as shown in FIG. In the case of FIG. 12, the rotating electric machine 40 may be configured with a delta connection instead of a star connection. Moreover, in the case of FIG. 12, since the rotating electric machine 40 is not controlled, the voltage command value vector Vref is zero. Therefore, in the case of FIG. 12, the voltage command value vector Vref explained in FIG. 9 may be treated as 0. In the case of FIG. 12, the zero-phase voltage command value vector V0ref is used to control the current flowing from the quick charger 88 to the neutral point O of the rotating electrical machine 40 to the target current. In addition, in FIG. 12, the intermediate terminal B is not provided in the assembled battery 20, and the assembled battery 20 does not need to be divided into the first storage battery 21 and the second storage battery 32.

The control device 70 determines the timing for changing the switching state of a switch in any one of the U-phase, V-phase, and W-phase from on to off, and changing the switching state of a switch in any one of the remaining phases from off to on. The first control controls the switching state so that the switching timing falls within a predetermined period, and the second control controls the switching state so that each of the U-phase, V-phase, and W-phase switches simultaneously. It may be switched based on the amount of noise. The amount of noise referred to here includes, for example, a noise current generated by switching all or some of the switches, a surge voltage generated by switching all or some of the switches, and the like. Noise current and surge voltage are detected by a detector (not shown). The control device 70 performs the first control in a first region where the noise current and surge voltage are relatively large, and performs the second control in a second region where the noise current is relatively smaller than the first region. good. That is, when the amount of noise generated by switching all or some of the switches is larger than a predetermined amount, the control device 70 determines the timing for switching the switching state of the switches in any one phase from on to off, and the timing for switching the switching state of the switches in any one phase from on to off. The switching state may be controlled so that the timing of switching the switching state of the switch in any one phase from off to on falls within a predetermined period. This enables appropriate control according to noise current and surge voltage.

In the above-described embodiment, the inverter 30 and the rotating electric machine 40 have three phases, but the number of phases is not limited to this. For example, as shown in FIG. 13, the number of phases may be five or seven phases. In FIG. 13, in the inverter 30, X-phase upper and lower arm switches QXH, QXL and diodes DXH, DXL are added, and Y-phase upper and lower arm switches QYH, QYL and diodes DYH, DYL are added. Furthermore, in the rotating electric machine 40, an X-phase winding 41X and a Y-phase winding 41Y are added. Furthermore, in the power conversion device 10, an X-phase conductive member 32X and a Y-phase conductive member 32Y are added.

Although the first storage battery 21 and the second storage battery 22 have been described as being composed of secondary batteries, they are not limited to this, and may be composed of capacitors.

The control unit and the method described in the present disclosure are implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. may be done. Alternatively, the controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

DESCRIPTION OF SYMBOLS 10... Power conversion device, 21... First storage battery, 22... Second storage battery, 30... Inverter, U, V, W phase upper arm switch... QUH, QVH, QWH, U, V, W phase lower arm switch... QUL, QVL, QWL, 40... Rotating electric machine, U, V, W phase winding... 41U, 41V, 41W, 60... Connection route, 70... Control device, O... Neutral point

Claims (12)

a rotating electrical machine (40) having star-connected windings (41U, 41V, 41W);
an inverter (30) electrically connected to the winding and having a plurality of phases;
In a first power storage unit (21) and a second power storage unit (22) connected in series, the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit are connected to the neutral point (O) of the winding. A power conversion device (10) comprising a connection path (60) for electrical connection,
By switching the switches (QUH, QVH, QWH, QUL, QVL, QWL) provided for each phase in the inverter, a voltage is generated between the first power storage unit and the second power storage unit via the connection path. A control unit (70) that performs power transfer control to flow current,
In the power transfer control, the control unit determines a timing for switching a switching state of the switch in one of the phases from on to off, and a timing for switching a switching state of the switch in any one of the remaining phases to off. A power converter device in which a time difference from a timing when the switch is turned on is kept within a predetermined period of 1/2 or less of one switching period in the switch. The control unit includes:
Of each phase, the phase with the largest absolute value of the voltage command value for the winding is selected as the reference phase, and the phase with the next largest absolute value of the voltage command value for the winding is selected as the inversion phase,
Performing switching control of the switch in the reference phase based on a comparison between the voltage command value in the reference phase and a first carrier,
Performing switching control of the switch in the inversion phase based on a comparison between the voltage command value in the inversion phase and a second carrier having the same period as the first carrier,
The power conversion device according to claim 1, wherein a phase difference between the first carrier and the second carrier is set so that the time difference is within the predetermined period. The power conversion device according to claim 2, wherein the control unit sets the phase difference to 180 degrees. The control unit includes:
In each phase, controlling the switching of the switch based on a comparison between the voltage command value for the winding and the carrier;
Of each phase, the phase with the largest absolute value of the voltage command value for the winding is selected as the reference phase, and the phase with the next largest absolute value of the voltage command value for the winding is selected as the inversion phase,
Matching the sign of the voltage command value in the inversion phase and the sign of the voltage command value in the reference phase,
The switching state of the switch based on the magnitude comparison between the voltage command value and the carrier in the inversion phase is reversed with respect to the switching state of the switch based on the magnitude comparison between the voltage command value and the carrier in the reference phase. The power conversion device according to claim 1. The control unit includes:
obtaining a turn-on time of the switch in the reference phase based on the voltage of the reference phase;
obtaining a turn-off time of the switch in the inversion phase based on the voltage of the inversion phase;
Calculating an on-off time difference that is a time difference between the turn-on time and the turn-off time,
According to any one of claims 2 to 4, a predetermined offset for reducing the on-off time difference is set in the voltage command value of either the reference phase or the inverted phase based on the on-off time difference. The power conversion device described. 5. The control unit causes a voltage command value for performing power transfer control to be reflected in a voltage command value for a phase other than the reference phase and the inverted phase among each phase. The power conversion device described in . The control unit includes:
Two first and second basic vectors (V1, V2) adjacent to the voltage command value vector in αβ coordinates for controlling the rotating electrical machine, and positions at 60 degrees with respect to the first and second basic vectors, respectively. Select two third and fourth fundamental vectors (V3, V6) having a phase difference,
A zero phase for controlling the ratio of the output time of the first to fourth basic vectors to the one switching period to the voltage command value vector and the current flowing between the first power storage unit and the second power storage unit. Set based on the voltage command value vector,
The selected first to fourth fundamental vectors are output at least once in one switching period so that the phase difference between two consecutive fundamental vectors is 120 degrees. The power conversion device according to claim 1, which outputs a fundamental vector. When the amount of noise generated by switching the switch is larger than a predetermined amount, the control unit determines the timing for switching the switching state of the switch from on to off in any one phase, and the timing for switching the switching state of the switch in any one phase from on to off, and in the remaining one phase. The power converter device according to claim 1, wherein a time difference between a timing at which the switching state of the switch is switched from off to on is kept within a predetermined period of 1/2 or less of one switching cycle of the switch. A rotating electric machine (40) having windings (41U, 41V, 41W),
A power converter comprising an inverter (30) having switches (QUH, QVH, QWH, QUL, QVL, QWL) provided for each phase and electrically connecting the winding and the power storage unit (20). In the device (10),
An external charger can be connected to the winding and the negative terminal of the power storage unit,
In a state in which the winding and the negative terminal of the power storage unit are connected to the charger, the timing of switching the switching state of the switch in one of the phases from on to off, and any of the remaining ones. A power conversion device comprising a control unit (70) that keeps a time difference between a timing of switching the switching state of the switch from off to on in one phase within a predetermined period of 1/2 or less of one switching cycle of the switch. The power conversion device according to any one of claims 1 to 4, and 7 to 9, wherein the predetermined period is set to a period of 1/10 or less of the one switching period. a rotating electrical machine (40) having star-connected windings (41U, 41V, 41W);
an inverter (30) electrically connected to the winding and having a plurality of phases;
In a first power storage unit (21) and a second power storage unit (22) connected in series, the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit are connected to the neutral point (O) of the winding. a connection path (60) for electrical connection;
By switching the switches (QUH, QVH, QWH, QUL, QVL, QWL) provided for each phase in the inverter, a voltage is generated between the first power storage unit and the second power storage unit via the connection path. Applied to a power conversion device (10) comprising a control unit (70) that performs power transfer control to flow current,
The control unit (70) includes:
In the power transfer control, a timing for switching the switching state of the switch in any one of the phases from on to off, and a timing for switching the switching state of the switch in any one of the remaining phases from off to on. A program that causes a time difference between the switch and the switch to be within a predetermined period of 1/2 or less of one switching cycle of the switch. A rotating electric machine (40) having windings (41U, 41V, 41W),
A power converter comprising an inverter (30) having switches (QUH, QVH, QWH, QUL, QVL, QWL) provided for each phase and electrically connecting the winding and the power storage unit (20). applied to the device (10);
An external charger can be connected to the winding and the negative terminal of the power storage unit,
In the control section (70),
In a state where the winding and the negative terminal of the power storage unit are connected to the charger, the timing of switching the switching state of the switch in one of the phases from on to off, and any of the remaining ones. A program that causes a time difference between a timing of switching a switching state of the switch from off to on in one phase of the switch to be within a predetermined period of 1/2 or less of one switching period of the switch.

Images