JP5733259B2 - Rotating machine control device - Google Patents

Description

  The present invention relates to a control device for a rotating machine that controls a control amount of the rotating machine by operating an inverter.

  In recent years, brushless motors have been increasingly used as driving motors for automobiles. However, unlike other industrial equipment and electric vehicles, automobiles use only the power of a battery mounted in a limited space, with the acceleration torque that starts when the vehicle stops and the power that generates torque until high-speed cruise. In order to meet these requirements, a very wide range of operating characteristics must be realized in a small size.

  Here, in order to realize a wide range of operation characteristics, for example, as seen in Patent Document 1 below, it has been proposed to operate the motor by switching the number of turns of the stator winding as needed.

JP 2010-207010 A

  The idea as described in Patent Document 1 has been known for a long time, and a large number of large-capacity semiconductor switches are required to realize it, and the control device becomes large.

  Therefore, it is difficult to implement the technique described in Patent Document 1 in a limited space such as a passenger car. In fact, the technology exemplified in the cited document 1 has been put into practical use in fields where there are relatively few restrictions on the mounting space, such as for elevators, but has not yet been put into practical use for automobiles.

  The present invention has been made in the process of solving the above-described problems, and an object thereof is to provide a control device for a rotating machine that can change the characteristics of a stator winding with a simple configuration. .

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

  The invention described in claim 1 includes a first stator winding (14) insulated from each other, and a second stator winding (16) having a rated voltage larger than that of the first stator winding. A first inverter (INV1) and a second inverter (INV2) connected to each of the first stator winding and the second stator winding to control the control amount of the rotating machine (10). Operating means (40) for operating each of the first DC voltage source, a first state in which the voltage of the second DC voltage source is applied to both the first inverter and the second inverter, and the second DC voltage source Between a positive DC bus (Lp1) of the first inverter and a positive DC bus (Lp2) of the second inverter to switch between a second state in which voltage is applied only to the second inverter; and Negative of the first inverter A first switch means (30) for opening and closing at least one of a side DC bus (Ln1) and a negative side DC bus (Ln2) of the second inverter, and the first switch means than the first switch means. A state in which a voltage of a first DC voltage source provided on the inverter side and having a terminal voltage lower than that of the second DC voltage source is applied to the first inverter, and a voltage of the first DC voltage source; For a pair of states in which the application is cut off, the second switch means (32) for switching between them, and when the rotational speed of the rotating machine is low, the first switch means is opened and the second switch means Switching means (4) for switching the first switch means to a closed state and switching the second switch means to an open state by closing the switch means and increasing the rotational speed of the rotating machine. ) And, characterized in that it comprises a.

  In the above invention, the first stator winding having a small rated voltage is connected to the second DC voltage source only when the rotational speed of the rotating machine becomes high, so that the second stator winding generates heat. While avoiding reaching the limit, the output in the high rotation region can be secured. In addition, since such switching can be realized by the first switch means and the second switch means, it can be realized by a relatively simple configuration.

1 is a system configuration diagram according to a first embodiment. FIG. The time chart which shows the procedure of the switching process concerning the embodiment. The figure which shows the effect of the same embodiment. The figure which shows the characteristic of the electric power generated by a generator. The figure which shows the electric power generation characteristic in the modification of the said embodiment.

  Hereinafter, an embodiment in which a control device for a rotating machine according to the present invention is applied to a control device for a rotating machine mounted on an electric power steering will be described with reference to the drawings.

  The rotating machine (electric motor 10) shown in FIG. 1 is mounted on an electric power steering, and here, a permanent magnet synchronous machine is assumed. The electric motor 10 includes a rotor 12, a first stator winding 14, and a second stator winding 16. Here, the first stator winding 14 includes three stator windings of a U-phase coil wu1, a V-phase coil wv1, and a W-phase coil ww1, which are connected to each other at a neutral point. . The second stator winding 16 includes three stator windings of a U-phase coil wu2, a V-phase coil wv2, and a W-phase coil ww2, which are connected to each other at a neutral point. Although the first stator winding 14 and the second stator winding 16 are insulated from each other, they are wound around the same stator core.

  In particular, in the present embodiment, the first stator winding 14 and the second stator winding 16 both maintain a three-phase symmetry (so that the phase difference is 120 degrees each). ) Wired. Further, each phase of the first stator winding 14 and the corresponding phase of the second stator winding 16 are shifted by a predetermined phase. The predetermined phase is preferably 30 degrees in electrical angle.

  Here, the rated voltage (continuous rating) of the second stator winding 16 is larger (N times) than the rated voltage of the first stator winding 14. In the present embodiment, this setting is realized by making the number of turns of the second stator winding 16 larger than the number of turns of the first stator winding 14. For example, when the rated voltage of the first stator winding 14 is “12V” and the rated voltage of the second stator winding 16 is “48V”, the number of turns of the second stator winding 16 Is realized by making the number of turns of the first stator winding 14 four times.

  The first stator winding 14 is connected to a first DC voltage source (first battery 20) via a first inverter INV1. The first inverter INV1 includes three sets of series connection bodies of switching elements S ¥ p1, S ¥ n1 (¥ = u, v, w), and the connection point of each series connection body is the first stator. The windings 14 are connected to the U, V, and W phases, respectively. These switching elements S ¥ # 1 (¥ = u, v, w; # = p, n) are respectively connected in reverse parallel with a diode D ¥ # 1. In the present embodiment, an N-channel MOS field effect transistor is illustrated as the switching element S ¥ # 1. Therefore, the diode D ¥ # 1 may be a body diode of the switching element S ¥ # 1.

  The second stator winding 16 is connected to a second DC voltage source (second battery 22) via a second inverter INV2. The second inverter INV2 includes three sets of series connection bodies of switching elements S ¥ p2, S ¥ n2 (¥ = u, v, w), and the connection point of each series connection body is the second stator. The windings 16 are connected to the U, V, and W phases, respectively. Each of these switching elements S ¥ # 2 (¥ = u, v, w; # = p, n, hereinafter this notation is followed) is connected to a diode D ¥ # 2 in antiparallel. In the present embodiment, an N channel MOS field effect transistor is illustrated as the switching element S ¥ # 2. Therefore, the diode D ¥ # 2 may be a body diode of the switching element S ¥ # 2.

  The terminal voltage of the first battery 20 is set according to the rated voltage of the first stator winding 14, and the terminal voltage of the second battery 22 is set to the rated voltage of the second stator winding 16. Is set according to That is, the terminal voltage of the second battery 22 is higher than the terminal voltage of the first battery 20. In particular, in this embodiment, the terminal voltage of the second battery 22 is N times the terminal voltage of the first battery 20.

  The negative side DC bus Ln1 of the first inverter INV1 and the negative side DC bus Ln2 of the second inverter INV2 are short-circuited. On the other hand, the positive side DC bus Lp1 of the first inverter INV1 and the positive side DC bus Lp2 of the second inverter INV2 are connected via the first switch means 30. Incidentally, in the present embodiment, as the first switch means 30, a series connection body of a pair of N-channel MOS field effect transistors whose sources are short-circuited with each other is illustrated.

  The positive side DC bus Lp1 of the first inverter INV1 and the positive terminal of the first battery 20 are connected via a second switch means 32. Incidentally, in the present embodiment, as the second switch means 32, a series connection body of a pair of N channel MOS field effect transistors whose sources are short-circuited with each other is illustrated.

  The controller 40 is an operation means for operating the first inverter INV1 and the second inverter INV2 in order to control the control amount (torque) of the electric motor 10. That is, for example, by applying well-known vector control or rectangular wave energization control, the operation signal g ¥ # 1 of the switching element S ¥ # 1 constituting the first inverter INV1 is generated and output, and the second The operation signal g ¥ # 2 of the switching element S ¥ # constituting the inverter INV2 is generated and output.

  The controller 40 further opens / closes this by outputting the operation signal m1 to the first switch means 30, or opens / closes this by outputting the operation signal m2 to the second switch means 32. . That is, the controller 40 constitutes a switching unit in the present embodiment.

  FIG. 2 shows an opening / closing operation method for the first switch means 30 and the second switch means 32. As illustrated, in the present embodiment, when the rotational speed ω of the electric motor 10 is equal to or higher than the first threshold th1, the operation signal m1 for the first switch means 30 is switched to the on operation command, and the second The operation signal m2 for the switch means 32 is switched to an off operation command. On the other hand, when the rotational speed ω of the electric motor 10 is equal to or lower than the second threshold th2 (<th1), the operation signal m1 for the first switch means 30 is switched to the OFF operation command, and the second switch means 32 is used. The operation signal m2 for is switched to an on operation command. Here, the provision of a pair of different thresholds (first threshold th1 and second threshold th2) is for setting a known hysteresis, thereby avoiding the occurrence of a hunting phenomenon. .

  When the rotational speed ω is equal to or higher than the first threshold th1, the terminal voltage of the second battery 22 is applied to the first stator winding 14. As described above, the terminal voltage of the second battery 22 is set according to the rated voltage of the second stator winding 16 that is higher than the rated voltage of the first stator winding 14. Nevertheless, the application of the terminal voltage of the second battery 22 to the first stator winding 14 is allowed only when the motor 10 is rotating at high speed. That is, even when the continuous rated voltage of the first stator winding 14 is lower than the terminal voltage of the second battery 22, the application period of the terminal voltage of the second battery 22 is relatively short. Then, the first stator winding 14 does not reach the heat generation limit. Focusing on this point, in the present embodiment, the processing shown in FIG. 2 is performed.

  In this process, in cooperation with the setting of the first stator winding 14 and the second stator winding 16, it is possible to secure the torque from the low speed range to the high speed range of the electric motor 10. It is what. This will be described below.

  Now, the terminal voltage of the first battery 20 is the voltage Vbatt, the voltage induced in the first stator winding 14 is the counter electromotive voltage Erev, and the impedance of the first stator winding 14 is the impedance. Let it be Z. In this case, the current value I1 flowing through the first stator winding 14 by using the first battery 20 is expressed by the following equation (c1).

I1 = (Vbatt−Erev) / Z (c1)
On the other hand, in the present embodiment, the impedance of the second stator winding 16 is N ＾ 2 times the impedance Z of the first stator winding 14. In this embodiment, the number of turns of the second stator winding 16 is set to N times the number of turns of the first stator winding 14 so that the rated voltage of the second stator winding 16 is reduced. This is because the accommodation space area of the second stator winding 16 and the first stator winding 14 is set equal to N times the rated voltage of the first stator winding 14. That is, the inductance of the coil is proportional to the square of the number of turns, and the resistance value of the coil is proportional to the length and inversely proportional to the cross-sectional area. Here, if the accommodation space areas of the second stator winding 16 and the first stator winding 14 are equal, the length of the coil of the second stator winding 16 is N times, The cross-sectional area of the coil is 1 / N times the cross-sectional area of the coil of the first stator winding 14. Therefore, the resistance value is also N ^ 2.

  On the other hand, since the counter electromotive voltage of the stator winding is proportional to the number of turns, the counter electromotive voltage of the second stator winding 16 is N times the counter electromotive voltage Erev of the first stator winding 14. For this reason, the current value I2 that can be passed through the second stator winding 16 by using the second battery 22 is expressed by the following equation (c2).

I2 = (N · Vbatt−N · Erev) / N · N · Z
= (Vbatt-Erev) / N · Z (c2)
As can be seen from the above equation (c2), the current value I2 that can be passed through the second stator winding 16 is "1 / N" times the current value I1 that can be passed through the first stator winding 14. However, the torque is proportional to “current × number of turns”. For this reason, the torque generated in the first stator winding 14 by using the first battery 20 and the torque generated in the second stator winding 16 by using the second battery 22 are the same. .

  On the other hand, when the terminal voltage of the second battery 22 is applied to the first stator winding 14, the current value I1 ′ that can be passed through the first stator winding 14 is expressed by the following equation (c3) Expressed.

I1 ′ = (N · Vbatt−Erev) / Z (c3)
For this reason, as shown in FIG. 3, a torque larger than the torque generated in the second stator winding 16 by using the second battery 22 can be generated by the first stator winding 14. . In FIG. 3, the solid line indicates the torque generated in the first stator winding 14 using the first battery 20 and the torque generated in the second stator winding 16 using the second battery 22. On the other hand, the alternate long and short dash line indicates the torque generated in the first stator winding 14 using the second battery 22. Incidentally, the maximum torque Trqmax is determined by the rated current of the inverters INV1, INV2, etc.

  Thus, according to this embodiment, the maximum output of the electric motor 10 can be increased. In addition, the output of the electric motor 10 can be further improved by driving both the inverters INV1 and INV2. Further, in the region where torque can be generated in the second stator winding 16, the torque ripple of the electric motor 10 can be reduced. This is because a phase difference is provided between each phase of the first stator winding 14 and a corresponding phase of the second stator winding 16 as described above. In particular, when the phase difference is “30 °”, the torque ripple reduction effect becomes significant.

The reason why the second switch means 32 is opened when the first switch means 30 is closed is to prevent an excessively high voltage from being applied to the first battery 20. is there.
<Other embodiments>
The above embodiment may be modified as follows.

“Operation method of rotating machine”
Not limited to power running. The setting of the above embodiment is particularly excellent in improving the power generation efficiency during regeneration. That is, in the synchronous generator, the generated power can be increased as the generated voltage is increased as the rotational speed increases as shown in FIG. 4 under the condition that the generated current is lower than the rated current. Therefore, in the high rotation speed region, the generated power can be increased as shown in FIG. 5 by applying the terminal voltage of the second battery 22 to the first stator winding 14. That is, when the rotational speed ω is smaller than the first threshold th1, the terminal voltage of the first battery 20 is applied to the first stator winding 14, so that the power generation startable rotational speed ω1 is This is lower than the power generation start rotational speed ω2 when the terminal voltage of the second battery 22 is constantly applied to the stator winding 14. When the rotational speed ω reaches the first threshold th1, the second battery 22 is connected to the first stator winding 14, whereby the generated power can be increased from the power W1 to the power W2. .

"About the first switch means (30)"
It is not limited to opening and closing between the positive side DC bus Lp1 of the first inverter INV1 and the positive side DC bus Lp2 of the second inverter INV2. For example, it may open and close between the negative side DC bus Ln1 of the first inverter INV1 and the negative side DC bus Ln2 of the second inverter INV2. Further, between the positive side DC bus Lp1 of the first inverter INV1 and the positive side DC bus Lp2 of the second inverter INV2, the negative side DC bus Ln1 of the first inverter INV1 and the negative side of the second inverter INV2 Both of them may be opened and closed with respect to the DC bus Ln2.

  The first switch means is not limited to a semiconductor relay, and may be an electromagnetic relay, for example.

"Second switch means (32)"
The present invention is not limited to opening and closing between the positive side DC bus Lp1 of the first inverter INV1 and the positive terminal of the first battery 20. For example, it may be configured to open and close between the negative side DC bus Ln1 of the first inverter INV1 and the negative terminal of the first battery 20.

  The second switch means is not limited to a semiconductor relay, and may be, for example, an electromagnetic relay.

"About stator winding"
The stator windings connected to each other are not limited to three phases, and may be four phases or more, for example, five phases. Further, the connection method of each phase is not limited to the star connection, and may be a delta connection.

  Further, the phase difference between corresponding phases of the stator windings connected to each other may be zero.

"About rotating machines"
The rotating machine is not limited to the one mounted on the electric power steering, but may be a rotating machine for in-vehicle main machines, for example.

"About operation means"
The present invention is not limited to driving both the first inverter INV1 and the second inverter INV2. For example, the second inverter INV2 may be stopped at the rotational speed ω at which the solid line torque shown in FIG. However, in this case, there is a possibility that load torque is generated due to the return current flowing through the diode D ¥ # 2 of the second inverter INV2 due to the counter electromotive voltage generated in the second stator winding 16. For this reason, in this case, it is desirable to further provide switch means for opening and closing between the second stator winding 16 and the second inverter INV2, and to open the switch means.

“About the first inverter INV1 and the second inverter INV2”
Switching elements S ¥ # 1 and S ¥ # 2 are not limited to MOS field effect transistors, and may be IGBTs, for example.

  DESCRIPTION OF SYMBOLS 10 ... Electric motor, 14 ... 1st stator winding, 16 ... 2nd stator winding, 20 ... 1st battery, 22 ... 2nd battery, INV1 ... 1st inverter, INV2 ... 2nd Inverter.

Claims (2)

Control amount of a rotating machine (10) including a first stator winding (14) insulated from each other and a second stator winding (16) having a rated voltage larger than that of the first stator winding. Operating means for operating each of the first inverter (INV1) and the second inverter (INV2) connected to each of the first stator winding and the second stator winding ( 40)
A first state in which the voltage of the second DC voltage source is applied to both the first inverter and the second inverter, and a voltage in which the voltage of the second DC voltage source is applied only to the second inverter. In order to switch between two states, the positive-side DC bus (Lp1) of the first inverter and the positive-side DC bus (Lp2) of the second inverter, and the negative-side DC bus (Ln1) of the first inverter ) And the first switch means (30) for opening and closing at least one of the negative-side DC bus (Ln2) of the second inverter;
A voltage of a first DC voltage source provided on the first inverter side of the first switch means and having a terminal voltage lower than that of the second DC voltage source is applied to the first inverter. A second switch means (32) for switching between a state and a pair of states in which the application of the voltage of the first DC voltage source is cut off;
When the rotation speed of the rotating machine is low, the first switch means is opened and the second switch means is closed, and the rotation speed of the rotating machine is increased to close the first switch means. Switching means (40) for switching to a state and switching the second switch means to an open state;
A control device for a rotating machine.   The operating means is configured such that the first inverter winding is performed by the first inverter in a situation where the first switch means is opened by the switching means and the second switch means is closed. And operating both the first inverter and the second inverter to apply a voltage to the line and to apply a voltage to the second stator winding by the second inverter. Item 2. A rotating machine control device according to Item 1.

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