JP2013219869A - Controller of rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that it is difficult to apply a function, for operating a motor while switching the number of turns of a stator winding at any time, to an on-vehicle apparatus.SOLUTION: A first stator winding 14 is connected with a first battery 20 via a first inverter INV1. A second stator winding 16, having a rated voltage higher than that of the first stator winding 14, is connected with a second battery 22 via a second inverter INV2. The negative electrode side DC buses Ln1, Ln2 of the first inverter INV1 and the second inverter INV2 are short-circuited, and the neutrals of the first stator winding 14 and the second stator winding 16 are connected via first switch means 30. In a high rotation region, the first switch means 30 is closed, and the switching element S¥n1(¥=u, v, w) of the first inverter INV1 and the switching element S¥p2 of the second inverter INV2 are operated on/off.

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.

  According to the first aspect of the present invention, the first stator winding (14) in which a plurality of coils are star-connected, and the rated voltage is larger than that of the first stator winding, and the plurality of coils are star-shaped. Connected to each of the first stator winding and the second stator winding in order to control the control amount of the rotating machine (10) having the second stator winding (16) connected in a mold. Operating means (40) for operating each of the first inverter (INV1) and the second inverter (INV2), the neutral point of the first stator winding, and the second stator winding Switch means (30) for opening and closing between the neutral point, and the first stator winding and the second stator winding are housed in the rotating machine while being insulated from each other. The positive side DC bus (Lp1) of the first inverter and the positive side of the second inverter Between the side DC bus (Lp2) and between the negative DC bus (Ln1) of the first inverter and the negative DC bus (Ln2) of the second inverter are connected. When the rotation speed of the rotating machine is low, the operating means opens the switch means and the voltage of the first DC voltage source to the first stator winding via the first inverter. And applying the voltage of the second DC voltage source to the second stator winding via the second inverter, and the rotational speed of the rotating machine is increased, so that the switch means A switching element (S ¥ n1: ¥ = u, v, w) that is switched to a closed state and connected to one of the first inverters, and one of the second inverters Connected to No switching element (S ¥ p2: ¥ = u, v, w) and characterized in that the operation on and off to.

  In the above-described invention, the second stator winding having a lower rated voltage is applied with a voltage higher than the voltage of the first DC voltage source only when the rotational speed of the rotating machine is increased. While avoiding the stator winding from reaching the heat generation 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 for demonstrating the principle of the embodiment. The figure which shows the effect of the same 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, the phase difference between each phase of the first stator winding 14 and the corresponding phase of the second stator winding 16 is zero.

  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. Each of these switching elements S ¥ # 1 (¥ = u, v, w; # = p, n, hereinafter referred to as this notation) is connected to a diode D ¥ # 1 in antiparallel. 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. These switching elements S ¥ # 2 (¥ = u, v, w; # = p, n) are respectively connected in reverse parallel with a diode D ¥ # 2. 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 do not have an electrical path connecting them.

  The neutral point of the first stator winding 14 and the neutral point of the second stator winding 16 are connected via a 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. .

  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. .

  Here, when the first switch means 30 is opened and the second switch means 32 is closed, the first inverter INV1 and the second inverter INV2 are each operated by a well-known method. The That is, any one of the well-known switching modes 0 to 7 is selected independently by each of the first inverter INV1 and the second inverter INV2, so that each output voltage vector is any of the voltage vectors V1 to V7. It becomes.

  On the other hand, when the first switch means 30 is closed and the second switch means 32 is open, the switching element S ¥ n1 of the lower arm of the first inverter INV1 and the second switch The switching element S ¥ p2 of the upper arm of the inverter INV2 is turned on / off. At this time, the switching element S ¥ p1 of the upper arm of the first inverter INV1 and the switching element S ¥ n2 of the lower arm of the second inverter INV2 are fixed to the off state.

  There are eight operation states of the inverters INV1 and INV2 realized in this state. Specifically, when the switching element S ¥ n1 of the lower arm of the first inverter INV1 and the switching element S ¥ p2 of the upper arm of the second inverter INV2 are regarded as one inverter, the switching modes 0 to 7 It can correspond to each. That is, the switching mode 0 corresponds to a state in which all of the switching elements Sun1, Svn1, and Swn1 of the lower arm of the inverter INV1 are turned on, and the switching mode 7 corresponds to the switching element Sup2, of the upper arm of the inverter INV2. A state in which all of Svp2 and Swp2 are turned on corresponds.

  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 each phase of the first stator winding 14 is the back electromotive voltage Erev, and the impedance of the first stator winding 14 is Is an impedance 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− (√3) · Erev) / Z (c1)
In the above formula (c1), “(√3) · Erev” is a line back electromotive voltage. “(√3)” is caused by the fact that the angle between the lines is set to 120 °.

  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− (√3) · N · Erev) / N · N · Z
= (Vbatt- (√3) · 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, in the above-described case where the first switch means 30 is closed, the current value I that can be passed through the electric motor 10 is expressed by the following equation (c3).

I = (N · Vbatt− {√ (1 + N + N ^ 2)} · Erev) / {(1 + N ^ 2) · Z / 2}
.... (c3)
In the above formula (c3), due to the fact that the current path is as shown in FIG. 3 (a), the line back electromotive force voltage becomes “{√ (1 + N + N ^ 2)} · Erev ”. The impedance is the sum of the impedance Z of the first stator winding 14 and the impedance (= (N ^ 2) · Z) of the second stator winding 16, but the above formula (c2 ), The value is further “½” times.

  In the above formula (c3), the line back electromotive force and the impedance are both smaller than those shown in the above formula (c2). For this reason, the current value I is larger than that shown in the above equation (c2). And thereby, the torque of the electric motor 10 can be increased.

  That is, as shown in FIG. 4, when the first switch means 30 is opened by closing the first switch means 30 (the first inverter INV1 and the second inverter INV2 are independently set). A large torque can be generated as compared with the case of control. In FIG. 4, the solid line indicates torque generated in the first stator winding 14 using the first battery 20 and torque generated in the second stator winding 16 using the second battery 22. In contrast, the alternate long and short dash line closes the first switch means 30 and switches the switching element S ¥ n1 of the lower arm of the first inverter INV1 and the switching element S ¥ p2 of the upper arm of the second inverter INV2. Torque generated by turning on and off. Incidentally, the maximum torque Trqmax is determined by the rated current of the inverters INV1, INV2, etc.

  Thus, according to the present embodiment, the maximum output of the electric motor 10 can be increased by the control for closing the first switch means 30.

  When the rotational speed ω is equal to or higher than the first threshold th1, a voltage higher than that by the first battery 20 is applied to the first stator winding 14. Nevertheless, the reason why the first switch means 30 is allowed to be in the closed state is that this is limited to when the electric motor 10 rotates at a high speed. That is, even if the continuous rated voltage of the first stator winding 14 is about the terminal voltage of the first battery 20, if the application period of the voltage higher than that is relatively short, One stator winding 14 never reaches the heat generation limit. Focusing on this point, in the present embodiment, the processing shown in FIG. 2 is performed.

Incidentally, 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 by increasing the generated voltage as the rotational speed increases under the condition that the generated current is equal to or lower than the rated current. Therefore, in the high rotation speed region, the first switch means 30 is closed to increase the generated power by applying the terminal voltage of the second battery 22 to the motor 10 while increasing the current that can be passed through the motor 10. be able to.

"About the first switch means (30)"
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.

  Moreover, the setting of the axial direction of the stator windings connected to each other is not limited to the one exemplified in the above embodiment.

"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"
In the case where the first switch means 30 is closed as in the above embodiment, if the second switch means 32 is opened, the first battery is connected to the positive side DC bus Lp1 of the first inverter INV1. Since the voltage of 20 is not applied, all of the switching elements S ¥ p1 of the upper arm of the first inverter INV1 need not be fixed in the off state.

  For example, the positive side DC bus Lp1 of the first inverter INV1 and the positive side DC bus Lp2 of the second inverter INV2 are short-circuited, and the negative side DC bus Ln1 of the first inverter INV1 and the second inverter INV2 are short-circuited. In order to eliminate the electrical path to the negative electrode side DC bus Ln2, the operation method is changed as follows. That is, when the first switch means 30 is closed, the switching element S ¥ p1 of the upper arm of the first inverter INV1 and the switching element S ¥ n2 of the lower arm of the second inverter INV2 are turned on / off. Turn off. At this time, it is desirable that the switching element S ¥ n1 of the lower arm of the first inverter INV1 and the switching element S ¥ p2 of the upper arm of the second inverter INV2 are fixed in the off state.

“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 (3)

A first stator winding (14) in which a plurality of coils are star-connected, and a second stator in which the rated voltage is larger than that of the first stator winding and the coils are star-connected A first inverter (INV1) connected to each of the first stator winding and the second stator winding in order to control a control amount of the rotating machine (10) including the child winding (16). And operating means (40) for operating each of the second inverter (INV2);
Switch means (30) for opening and closing between a neutral point of the first stator winding and a neutral point of the second stator winding;
With
The first stator winding and the second stator winding are housed in the rotating machine while being insulated from each other,
Between 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 second inverter Any one of the negative electrode side DC buses (Ln2) is connected,
The operation means includes
When the rotational speed of the rotating machine is low, the switch means is opened, and the voltage of the first DC voltage source is applied to the first stator winding via the first inverter. The voltage of the second DC voltage source is applied to the second stator winding via the second inverter, and the rotational speed of the rotating machine is increased, so that the switch means is switched to the closed state and , A switching element (S ¥ n1: ¥ = u, v, w) connected to any one of the first inverters, and a switching not connected to any one of the second inverters A control device for a rotating machine, wherein an element (S ¥ p2: ¥ = u, v, w) is turned on / off. The switch means is a first switch means,
A second switch that switches between a pair of states in which the voltage of the first DC voltage source is applied to the first inverter and the application of the voltage of the first DC voltage source is cut off Means (32),
The operating means closes the second switch means when opening the first switch means, and opens the second switch means when closing the first switch means. The control apparatus for a rotating machine according to claim 1.   The operating means is a switching element (S ¥ p1) that is not connected to any one of the first inverters and any one of the second inverters during a period in which the switch means is closed. The control device for a rotating machine according to claim 1, wherein the switching element (S ¥ n2) connected to one side is maintained in an off state.

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