JP2010166716A - Controller and control system for rotating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a risk that a controller causes an increase in switching loss of an inverter in controlling model prediction. <P>SOLUTION: The controller predicts a current which flows in a motor generator, as to each of the cases where the operation state of an inverter IV is set at each voltage vector Vn (steps S10-S18). It selects a voltage vector where the deviation between these predicted currents and a command current is the minimum (step S22). It adopts a zero vector on the side where the number of times of switchover of the switching state is smaller (steps S28 and S30) when the voltage vector is switched over by this selection and the selected voltage vector is a zero vector (YES in step S24). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a control device for a rotating machine that controls a control amount of the rotating machine by operating a power conversion circuit including a switching element that electrically connects each of a positive electrode and a negative electrode of a DC power source to a terminal of the rotating machine, and It relates to the control system.

  As this type of control device, for example, as shown in Patent Document 1 below, a command voltage for each phase is calculated in order to feedback control the current flowing in each phase of the three-phase motor to a command value, and the calculated command A device that performs triangular wave comparison PWM control for operating the switching element of the inverter based on the magnitude of the voltage and the triangular wave shaped carrier has been proposed and put into practical use.

  However, when the triangular wave comparison PMW control is performed even in a region where the command voltage is larger than the input voltage of the inverter, the output voltage of the inverter includes large harmonics, which is a response to the current flowing through the three-phase motor. There are problems that affect it. This problem is due to the fact that the current control system is designed on the assumption that the output voltage of the inverter can be a command voltage.

  Therefore, conventionally, for example, as can be seen in Non-Patent Document 1 below, the current flowing through the three-phase motor when the operation state of the inverter is set in various ways is predicted, and the deviation between the predicted current and the command current is minimized. There has also been proposed what performs so-called model predictive control in which an inverter is operated in an operation state that can be realized. According to this, since the inverter is operated so as to optimize the behavior of the current predicted based on the actual output voltage of the inverter, the above problem can be avoided.

  As another technique for dealing with the above problem, there is a technique described in Patent Document 2 below.

JP 2002-223590 A Japanese Patent Laid-Open No. 10-174453

Kawai, Zanma, Ishida, "Optimum control of PMSM using model predictive control", IEEJ National Convention, 2007

  By the way, according to the model predictive control, although the current control can be performed in consideration of the actual output voltage of the inverter, the number of switching of the inverter switching state realized thereby increases, resulting in the switching loss. May increase or surge may increase.

  The present invention has been made to solve the above problems, and an object of the present invention is to operate a power conversion circuit including a switching element that electrically connects each of a positive electrode and a negative electrode of a DC power source to a terminal of a rotating machine. Accordingly, an object of the present invention is to provide a control device and a control system for a rotating machine that can suitably suppress an increase in switching loss of a power conversion circuit when controlling the control amount of the rotating machine.

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

  According to a first aspect of the present invention, there is provided a rotating machine that controls a control amount of the rotating machine by operating a power conversion circuit including a switching element that electrically connects each of a positive electrode and a negative electrode of a DC power source to a terminal of the rotating machine. Model predictive control means for predicting an electrical state quantity of the rotating machine for each of a plurality of operation states of the power conversion circuit and operating the power conversion circuit based on the prediction And the model predictive control means reduces the number of switching of the switching state of the switching element of the power conversion circuit among the pair of zero vectors when the operation state of the power conversion circuit is switched to the zero vector. It is characterized by using the person who can do it.

  There is no difference in the output voltage of the power conversion circuit between the case where the operation state of the power conversion circuit is set to one of the pair of zero vectors and the case where the other is set to the other. However, the state quantities predicted by the model predictive control are the same. For this reason, it cannot be determined from the predicted state quantity which one of the pair of zero vectors should be used.

  On the other hand, when switching the switching state of the power conversion circuit, the power loss of the power conversion circuit increases as the number of switching elements to be switched increases. In the above-described invention, in view of this point, an increase in power loss can be suitably suppressed by using a method that can reduce the number of switching states.

  According to a second aspect of the present invention, in the first aspect of the invention, the model prediction control unit predicts a current flowing through the rotating machine when each of the operation states of the power conversion circuit is set to a plurality of types. Means for operating the power conversion circuit by determining an actual operation state of the power conversion circuit based on the predicted current and its target value.

  In the above invention, since the power conversion circuit is operated based on the predicted current, the current that actually flows through the rotating machine can be controlled based on the target value.

  According to a third aspect of the present invention, in the second aspect of the invention, the model predictive control unit avoids the power conversion circuit from avoiding an operation state corresponding to a case where the predicted current is out of an allowable range. It is characterized by operation.

  In the said invention, it can avoid that the electric current which flows through a rotary machine becomes an unexpected thing.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the model prediction control means predicts the torque of the rotating machine when each of the operation states of the power conversion circuit is set in a plurality of ways. And operating the power conversion circuit by determining an actual operation state of the power conversion circuit based on the predicted torque and the target value.

  In the above invention, since the power conversion circuit is operated based on the predicted torque, the actual torque of the rotating machine can be controlled based on the target value.

  A fifth aspect of the present invention is a rotating machine control system comprising the rotating machine control device according to any one of the first to fourth aspects and the power conversion circuit.

  In the said invention, the system which can suppress suitably the switching loss of a power converter circuit is implement | achieved, performing model prediction control by providing the said model prediction control means.

1 is a system configuration diagram according to a first embodiment. FIG. The figure which shows the setting aspect of the command electric current concerning the embodiment. The figure which shows a voltage vector. The flowchart which shows the process sequence regarding control of the motor generator concerning the said embodiment. The flowchart which shows the process sequence regarding control of the motor generator concerning 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a control device for a rotating machine according to the present invention is applied to a control device for a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of a motor generator control system according to this embodiment. The motor generator 10 is a three-phase permanent magnet synchronous motor. The motor generator 10 is a rotating machine (saliency pole machine) having saliency. Specifically, the motor generator 10 is an embedded magnet synchronous motor (IPMSM).

  The motor generator 10 is connected to a high voltage battery 12 via an inverter IV and a boost converter CV. Here, the boost converter CV boosts the voltage (for example, “288V”) of the high-voltage battery 12 up to a predetermined voltage (for example, “666V”). On the other hand, the inverter IV includes a series connection body of the switching elements Sup and Sun, a series connection body of the switching elements Svp and Svn, and a series connection body of the switching elements Swp and Swn. The points are connected to the U, V, and W phases of the motor generator 10, respectively. In the present embodiment, insulated gate bipolar transistors (IGBTs) are used as the switching elements Sup, Sun, Svp, Svn, Swp, and Swn. In addition, diodes Dup, Dun, Dvp, Dvn, Dwp, and Dwn are connected in antiparallel to these.

  In this embodiment, the following is provided as detection means for detecting the state of the motor generator 10 and the inverter IV. First, a rotation angle sensor 15 that detects a rotation angle θ (electrical angle) of the motor generator 10 is provided. Further, current sensors 16, 17, and 18 that detect currents iu, iv, and iw flowing through the phases of the motor generator 10 are provided. Furthermore, a voltage sensor 19 for detecting an input voltage (power supply voltage VDC) of the inverter IV is provided.

  The detection values of the various sensors are taken into the control device 14 constituting the low pressure system via the interface 13. The control device 14 generates and outputs an operation signal for operating the inverter IV and the converter CV based on the detection values of these various sensors. Here, the signals for operating the switching elements Sup, Sun, Svp, Svn, Swp, Swn of the inverter IV are the operation signals gup, gun, gvp, gvn, gwp, gwn. The signals for operating the two switching elements of the boost converter CV are the operation signals gup and gcn.

  The control device 14 operates the inverter IV so as to obtain a command current for realizing the required torque for the motor generator 10. FIG. 2 shows the setting of the command current according to this embodiment.

In FIG. 2, a one-dot chain line is a maximum torque curve showing a command current determined by the maximum torque control that realizes the maximum torque with the minimum current as the current of the rotating two-dimensional coordinate system (dq coordinate system). On the other hand, the broken line is a current limit ellipse indicating the upper limit value of the current that can be realized by the power supply voltage VDC and the electrical angular velocity ω. This is because the current vector (id, iq) when the norm of the output voltage vector (vd, vq) becomes the upper limit value corresponding to the power supply voltage VDC in the voltage equations shown in the following equations (c1) and (c2). It can be derived as a trajectory.
vd = (R + pLd) id−ωLqiq (c1)
vq = ωLdid (R + pLq) iq + ωΦ (c2)
Incidentally, in the above formulas (c1) and (c2), the electrical angular velocity ω, the differential operator p, the d-axis inductance Ld, the q-axis inductance Lq, and the armature flux linkage constant Φ are used.

  In FIG. 2, a two-dot chain line is an equal torque curve indicating a current that can generate the same torque as the torque at the intersection P between the maximum torque curve and the current limit ellipse. Here, on the side of the equal torque curve where the d-axis current is decreased from the intersection point P (the side where the negative d-axis current is increased), although it falls within the region surrounded by the current-limiting ellipse, the d-axis is greater than the intersection point P. The side on which the current is increased (the side on which the negative d-axis current is reduced) is out of the region surrounded by the current limiting ellipse. In other words, the side where the d-axis current is decreased from the intersection P can be realized by the power supply voltage VDC, but the side where the d-axis current is increased from the intersection P cannot be realized by the power supply voltage VDC. This is because the contribution of the induced voltage ωΦ to the d-axis voltage can be reduced by increasing the d-axis current negatively in the above formula (c2).

  In view of the above, in this embodiment, the command current is defined by a solid line. That is, when the point on the maximum torque curve for realizing the required torque is in the region within the current limit ellipse, the maximum torque curve is set as the command current, and when there is not, the d-axis direction of the equal torque curve The part that performs field-weakening control that weakens the magnetic flux is defined as a command current. Since the current limit ellipse depends on the power supply voltage VDC and the electrical angular velocity ω, the command current is variably set according to the power supply voltage VDC and the electrical angular velocity ω.

  In this embodiment, in order to control the current flowing through the motor generator 10 to the command current, the current flowing through the motor generator 10 is predicted when the operation state of the inverter IV is set, and the operation state in which this predicted current is close to the command current. Model predictive control for operating the inverter IV is performed so that Here, the operation state of the inverter IV will be described first.

  The operation state of the inverter IV can be expressed by eight voltage vectors shown in FIG. Here, for example, the voltage vector representing the operation state (indicated as “lower” in the figure) in which the low-potential side switching elements Sun, Svn, Swn are turned on is the voltage vector V0, and the high-potential side switching element A voltage vector representing an operation state (indicated as “upper” in the drawing) in which Sup, Svp, and Swp are turned on is a voltage vector V7. These voltage vectors V0 and V7 are for short-circuiting all phases of the motor generator 10 and are called zero vectors because the voltage applied to the motor generator 10 from the inverter IV becomes zero. On the other hand, the remaining six voltage vectors V1 to V6 are defined by an operation pattern in which switching elements that are turned on exist in both the upper arm and the lower arm, and are called non-zero vectors. Yes. As shown in FIG. 3B, the voltage vectors V1, V3, and V5 correspond to the positive sides of the U phase, the V phase, and the W phase, respectively.

  In this embodiment, when the operation state of the inverter IV is set to each of these eight voltage vectors V0 to V7, the current flowing through the motor generator 10 is predicted, and based on this, the voltage vector to be set to the actual operation state is selected.

  FIG. 4 shows a processing procedure of model predictive control according to the present embodiment. The process shown in FIG. 4 is repeatedly executed by the control device 14 at a predetermined cycle, for example.

In this series of processing, first, in step S10, the parameter n for designating the voltage vectors V0 to V7 is set to zero. In subsequent step S12, a current when the operation state of the inverter IV is set to the voltage vector Vn is predicted (currents ide and iq are calculated). This is because the following equations (formulas (c3) and (c4)) obtained by solving the above formulas (c1) and (c2) with respect to the differential term of the current are discretized and the current one step ahead is predicted. It can be carried out.
pid
= − (R / Ld) id + ω (Lq / Ld) iq + vd / Ld (c3)
piq
= −ω (Ld / Lq) id− (Rd / Lq) iq + vq / Lq−ωΦ / Lq (c4)
Incidentally, in the state equation expressed by the above equations (c3) and (c4), the output voltage vector (vd, vq) is selected when the zero vector (V0, V7) is selected as the operation state of the inverter IV. When a zero vector is selected and a non-zero vector is selected, the vector norm shown in FIG. 3B is used as the power supply voltage VDC, and this is a vector obtained by dq conversion. The electrical angular velocity ω may be a value calculated based on a time differential calculation of the rotation angle detected by the rotation angle sensor 15. Furthermore, the initial value of the current is the current detected value id, iq. Specifically, the actual currents id, iq obtained by performing three-phase conversion on the actual currents iu, iv, iw detected by the current sensors 16-18.

  Furthermore, in this step S12, the three-phase current (iue, ive, iwe) is predicted by performing three-phase conversion on the predicted currents ide and iqe.

  In the subsequent step S14, it is determined whether or not the predicted maximum value of the three-phase currents iue, ive and iwe exceeds the threshold current Ith. Here, the threshold current Ith is the maximum allowable current of the inverter IV. Here, the maximum allowable current may be an upper limit value that can maintain the reliability of the inverter IV due to its structure. In addition, when a drive circuit that drives the inverter IV has a function of forcibly shutting down the inverter IV due to an excessively large current flowing through the inverter IV, a current that is not shut down. It is good also as an upper limit of. If an affirmative determination is made in step S14, the voltage vector Vn is excluded from candidates for the actual operation state of the inverter IV in step S16.

  When the process of step S16 is completed or when a negative determination is made in step S14, it is determined whether or not the parameter n is “7” in step S18. This process is for determining whether or not the prediction of the current when all of the voltage vectors V0 to V7 are in the operation state of the inverter IV is completed. If a negative determination is made in step S18, the parameter n is incremented by “1” in step S20, and the process returns to step S12.

  If it is determined in step S18 that the parameter n is “7”, in step S22, a voltage vector that minimizes the deviation between the command current and the predicted current is selected from among the operating states of the inverter IV. In a succeeding step S24, it is determined whether or not the voltage vector is a switching time different from the previous time and the selected current vector is a zero vector. If the determination in step S24 is affirmative, if the current voltage vector is an odd vector (step S26: YES), the voltage vector V0 is selected (step S28), and if it is an even vector (step S26). S26: NO), the voltage vector V7 is selected (step S30).

  When the processes of steps S28 and S30 are completed, or when a negative determination is made in step S24, the process proceeds to step S32. In step S32, the inverter IV is operated so that the operation state of the inverter IV becomes the selected voltage vector.

  In addition, when the process of step S32 is completed, this series of processes is once complete | finished.

  According to the above-described processing, when the voltage vector that can minimize the current deviation is a zero vector, either of the voltage vectors V0 and V7 may be used for the request to minimize the current deviation. However, the smaller number of switching elements whose switching state is switched is selected. For this reason, the loss resulting from switching of a switching state can be reduced, or the surge accompanying switching can be suppressed.

  Note that, according to the model predictive control, a voltage vector that minimizes the current deviation is selected, so that the zero vector is not selected every predetermined period unlike the triangular wave comparison PWM control. For this reason, depending on the operation region of motor generator 10, it is possible to reduce the switching frequency of the switching state as compared with the triangular wave comparison PWM control.

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

  (1) When switching the operation state of the inverter IV to the zero vector in the model predictive control, the one that can reduce the number of switching of the switching state of the switching element of the inverter IV among the pair of zero vectors is used. Thereby, the increase in power loss can be suppressed suitably.

  (2) When the operation state of the inverter IV is set to each of a plurality of types, the current flowing through the motor generator 10 is predicted, and the operation state in which the deviation between the predicted current and the command current is minimized is The actual operation state was assumed. Thereby, the current actually flowing through motor generator 10 can be suitably controlled to the command current.

  (3) The inverter IV was operated while avoiding an operation state corresponding to a case where the predicted currents iue, ive, and iwe were outside the allowable range. Thereby, it can be avoided that the current flowing through motor generator 10 becomes unexpected.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 5 shows a processing procedure of model predictive control according to the present embodiment. The process shown in FIG. 5 is repeatedly executed by the control device 14 at a predetermined cycle, for example. In FIG. 5, processes corresponding to the processes shown in FIG. 4 are given the same step numbers for convenience.

  In this series of processes, when an affirmative determination is made in step S18, torque T is predicted in step S40 based on the currents ide and iq predicted in step S12. Here, the torque T can be predicted by using the following model formula (formula (c5)).

T = p {Φ · ide + (Ld−Lq) · ide · iqe} (c5)
In the subsequent step S42, the voltage vector that minimizes the deviation between the predicted torque and the required torque is determined as the operating state of the inverter IV, and the process proceeds to step S24.

  According to this embodiment described above, the following effects can be obtained in addition to the effects (1) and (3) of the first embodiment.

  (4) The torque of the motor generator 10 is predicted for each case where the operation state of the inverter IV is set in a plurality of ways, and the operation state that minimizes the deviation between the predicted torque and the required torque is The actual operation state was assumed. Thereby, the actual torque of motor generator 10 can be suitably controlled to the required torque.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In each of the above embodiments, the current when all of the voltage vectors V0 to V7 are set to the operation state of the inverter IV is predicted, but the present invention is not limited to this. For example, when the current operation state of the inverter IV corresponds to an odd vector, the prediction processing when the zero vector V7 is set is excluded, and when the current operation state corresponds to the even vector, the prediction when the zero vector V0 is set is excluded. Processing may be eliminated.

  Further, regarding the non-zero vectors V1 to V6, instead of predicting the current for all of them, a part of the current may be predicted.

  In each of the above embodiments, model prediction control is performed in the entire region, but this is not a limitation. For example, in a region where the voltage usage rate is less than or equal to a predetermined value, the triangular wave comparison PWM control may be performed, and the model prediction control may be performed when the voltage usage rate becomes equal to or higher than a predetermined value. Further, for example, the model predictive control may be performed in a region where the voltage usage rate is equal to or lower than a predetermined value, and the well-known rectangular wave control may be performed when the voltage usage rate becomes higher than a predetermined level.

  The model predictive control is not limited to setting a voltage vector that sets the operation state of the inverter IV based on prediction of current and torque after one control cycle. For example, the voltage vector for operating the inverter IV in each of the plurality of control periods based on the prediction of the current and torque of the motor generator 10 in each control period when setting the voltage vector in each of the plurality of control periods. May be set.

  In the second embodiment, the torque is predicted based on the predicted current. However, the present invention is not limited to this. For example, the torque may be predicted by predicting the magnetic flux generated when the voltage vector is set.

  In the first embodiment, in the model predictive control, the voltage vector that minimizes the current deviation is selected to be the actual operation state of the inverter IV. However, the present invention is not limited to this. For example, the sum of weighted values obtained by multiplying each of the current deviation and the switching frequency by a predetermined coefficient may be minimized as an evaluation function. Furthermore, the sum of the number of switching elements for switching the switching state at the time of switching the voltage vector and the current deviation multiplied by a predetermined coefficient may be minimized as an evaluation function.

  In the second embodiment, the voltage vector that minimizes the deviation between the estimated torque and the required torque is selected from the candidates. However, the present invention is not limited to this. For example, the command current required by the maximum torque control or field weakening control is set, and the sum of the deviation between the actual current and the command current and the torque deviation multiplied by a predetermined coefficient is weighted. This may be minimized as an evaluation function.

  Further, for example, the sum of weighted values obtained by multiplying each of the torque deviation and the switching frequency by a predetermined coefficient may be minimized as an evaluation function. Furthermore, the sum of the number of switching elements for switching the switching state at the time of switching the voltage vector and the deviation of the torque multiplied by a predetermined coefficient may be minimized as an evaluation function.

  -The model used to predict the current is not limited to the model based on the fundamental wave. For example, a model including higher-order components for inductance and induced voltage may be used. The current predicting means is not limited to using a model formula, and may use a map. At this time, the input parameters of the map may be voltage (vd, vq) and electrical angular velocity ω, and may further include temperature and the like. Here, the map is storage means in which output parameter values corresponding to discrete values for input parameters are stored.

  The model used for predicting the current is not limited to a model that ignores iron loss, and may be a model that takes this into consideration.

  In the second embodiment, the torque is predicted using the model based on the predicted current, but the present invention is not limited to this. For example, a map using an estimated current as an input parameter may be used. At this time, temperature or the like may be further added to the input parameters of the map.

  The control amount of the rotating machine is not limited to torque, and may be, for example, a rotational speed.

  The rotating machine is not limited to the IPMSM, and may be any synchronous machine such as a surface magnet synchronous machine or a field winding type synchronous machine. Furthermore, it is not limited to a synchronous machine, but may be an induction rotating machine such as an induction motor.

  -As a rotary machine, not only what is mounted in a hybrid vehicle but the thing mounted in an electric vehicle may be sufficient. Further, the rotating machine is not limited to the one used as the main machine of the vehicle.

  The DC power source is not limited to the converter CV but may be a high voltage battery 12. In other words, the input terminal of the inverter IV may be connected to the high voltage battery 12 without providing the converter CV.

  DESCRIPTION OF SYMBOLS 10 ... Motor generator, 12 ... High voltage battery, 14 ... Control apparatus (one Embodiment of the control apparatus of a rotary machine).

Claims (5)

In a control device for a rotating machine that controls a control amount of the rotating machine by operating a power conversion circuit including a switching element that electrically connects each of a positive electrode and a negative electrode of a DC power source to a terminal of the rotating machine,
Predicting the electrical state quantity of the rotating machine for each of the case where the operation state of the power conversion circuit is set in a plurality of ways, comprising model prediction control means for operating the power conversion circuit based on the prediction,
When switching the operation state of the power conversion circuit to a zero vector, the model predictive control means can reduce the number of switching states of the switching state of the switching element of the power conversion circuit out of a pair of zero vectors. A control device for a rotating machine characterized by being used.   The model prediction control means includes means for predicting currents flowing through the rotating machine when the operation state of the power conversion circuit is set to a plurality of ways, respectively, and based on the predicted current and its target value. 2. The control device for a rotating machine according to claim 1, wherein an actual operation state of the power conversion circuit is determined to operate the power conversion circuit.   3. The control of a rotating machine according to claim 2, wherein the model predictive control unit operates the power conversion circuit while avoiding an operation state corresponding to one in which the predicted current is out of an allowable range. apparatus.   The model prediction control means includes means for predicting the torque of the rotating machine when each of the operation states of the power conversion circuit is set to a plurality of ways, based on the predicted torque and its target value, The controller for a rotating machine according to claim 1, wherein an actual operation state of the power conversion circuit is determined to operate the power conversion circuit. A control device for a rotating machine according to any one of claims 1 to 4,
A control system for a rotating machine comprising the power conversion circuit.

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