JP6144989B2 - Speed sensorless motor controller - Google Patents

Description

  The present invention relates to torque control of an electric motor, and in particular, makes the estimation of the initial speed and initial secondary magnetic flux of the electric motor highly accurate and makes the motor torque control highly accurate.

  A so-called speed sensorless motor control device that is not provided with a speed sensor is known from the viewpoint of enhancing the maintainability of the motor or obtaining a large output even if the motor is reduced (for example, Patent Document 1). , 2). When controlling the torque of the motor with such a speed sensorless motor control device, it is generally necessary to estimate the speed (angular speed) of the motor.

  FIG. 5 is a block diagram illustrating a configuration example of a conventional speed sensorless motor control device.

  The current detector 5 detects a current vector i flowing through the electric motor 6. The pick-up control unit 2 inputs the current vector i detected by the current detection unit 5, the DC current command I and the DC phase angle command θ1, and converts the current i flowing through the electric motor 6 into a DC current according to the command (I, θ1). A pick-up voltage command v0 for output is output.

ここで、Ｒ１は電動機６の一次抵抗、Ｌ１は一次自己インダクタンス、Ｌ２は二次自己インダクタンス、Ｍは相互インダクタンスである。 The actual magnetic flux estimator 9 calculates the actual magnetic flux vector φ2r of the electric motor 6 from the current vector i and the picked-up voltage command v0 by the equation (A).

Here, R1 is a primary resistance of the motor 6, L1 is a primary self-inductance, L2 is a secondary self-inductance, and M is a mutual inductance.

  The calculation timer 14 is a timer counter that is cleared to 0 at the edge of the pick-up control start command ST, and outputs a pick-up time t0.

  The initial value estimation unit 7 receives the current vector i, the actual magnetic flux vector φ2r, and the pick-up time t0, and outputs the initial speed ωm0 and the initial secondary magnetic flux φ20 of the electric motor 6.

  When the torque control start command SW is turned on, the torque control unit 1 uses the initial speed ωm0 and the initial secondary magnetic flux φ20, which are the outputs of the initial value estimation unit 7, as initial values, and based on the current vector i, A torque control voltage command V1 for controlling torque is output. In the example shown here, the torque control start command SW is in an OFF state when the electric power of the electric motor 6 is turned on.

  The switching unit 3 switches and outputs the pick-up voltage command v0 and the torque control voltage command V1 by the torque control start command SW. That is, until the torque control start command SW is turned on, the pick-up voltage command v0 is set as the voltage command V *, and when the torque control start command SW is turned on, the torque control voltage command V1 is output as the voltage command V *.

  The power converter 4 amplifies the voltage command V * and supplies power to the motor 6.

  With the above configuration, until the torque control start command SW is turned on, the pickup control unit 2, the actual magnetic flux estimation unit 9, the calculation timer 14, and the initial value estimation unit 7 use the initial speed ωm0 of the electric motor 6. And the initial secondary magnetic flux φ20 is estimated. When the torque control start command SW is turned on, torque control of the electric motor 6 is performed using the initial speed ωm0 and the initial secondary magnetic flux φ20 at the time when the SW is turned on as initial values. The timing for turning on the torque control start command SW is determined by the pick-up control execution time, the state of the initial speed ωm0 and the initial secondary magnetic flux φ20, and the like.

  Hereinafter, the operation of the initial value estimation unit 7 in the pick-up control until the torque control start command SW is turned on will be described in detail.

  The initial value estimation unit 7 estimates the initial speed ωm0 of the electric motor 6 from the movement of the actual magnetic flux vector φ2r, and estimates the initial secondary magnetic flux φ20. FIG. 6 is a configuration example of the initial value estimation unit 7.

  The actual magnetic flux memory 10 stores the actual magnetic flux estimation vector φ2r that changes every moment from the time 0 to the pick-up time t0. The actual magnetic flux extraction unit 11 extracts φ (t00), φ (t01), and φ (t02), which are actual magnetic flux estimation vectors φ2r at arbitrary three time points t00, t01, and t02, from the interval from time 0 to t0.

  As an example, the initial speed estimation unit 12 calculates the initial speed ωm0 using Expressions (B) to (G). In this method, first, the center R of a circle passing through the end points of the three vectors φ (t00), φ (t01), and φ (t02) is obtained by the equations (B) to (E).

ここで、（Ｆ１_Ａ，Ｆ１_Ｂ），（Ｆ２_Ａ，Ｆ２_Ｂ），（Ｒ_Ａ，Ｒ_Ｂ）は、各々、ベクトルＦ１，Ｆ２，Ｒの各成分である。

_{Here, (F1 A, F1 B)} , (F2 A, F2 B), (R A, R B) are each a respective component of the vectors F1, F2, R.

  Next, an angle θC between the vector φ (t00) and the vector φ (t02), as viewed from the center R of the circle, is obtained by Expression (F).

ここで、記号「×」はベクトルの外積を、記号「・」はベクトルの内積をそれぞれ示す。

Here, the symbol “×” indicates an outer product of vectors, and the symbol “·” indicates an inner product of vectors.

  Since the rotational speed of the electric motor 6 from time t00 to t02 (for example, several tens of milliseconds) can be regarded as substantially constant, the initial speed ωm0 can be finally obtained by the equation (G).

ここで、ｊは虚数単位、Ｔ２は電動機６の二次時定数で、Ｌ２／Ｒ２で得られる。Ｒ２は二次抵抗である。φｘｘは拾い上げ制御開始時の残留磁束である。なお、式（Ｈ）の第２項は、ベクトルＲに対する実磁束推定ベクトルφ２ｒの相対ベクトルとして求めることもできる。 The initial magnetic flux estimator 13 uses the current vector i to obtain the initial secondary magnetic flux φ20 using equation (H).

Here, j is an imaginary unit, T2 is a secondary time constant of the electric motor 6, and is obtained by L2 / R2. R2 is a secondary resistance. φxx is a residual magnetic flux at the start of pick-up control. Note that the second term of the equation (H) can also be obtained as a relative vector of the actual magnetic flux estimation vector φ2r with respect to the vector R.

JP 2001-211689 A JP 2001-211697 A

  When estimating the initial speed ωm0 of the electric motor 6 from the movement of the circular locus of the actual magnetic flux vector φ2r using the equations (B) to (G), the second term when the time t0 in the equation (H) changes. It can be considered that the initial speed ωm0 is estimated using the motion of the portion. Therefore, in general, the larger the magnitude of the vector of the second term portion of the equation (H), the smaller the influence of the error in the estimated value of the actual magnetic flux vector φ2r by the actual magnetic flux estimating unit 9, and hence the initial speed. The calculation accuracy of ωm0 is increased.

Here, in the speed sensorless motor control device described above, the pick-up control unit 2 outputs a pick-up voltage command v0 for making the current i flowing through the motor 6 a direct current as commanded (I and θ1). However, a control delay occurs in the control of the pick-up control unit 2. This control delay becomes more prominent when the initial speed ωm0 of the electric motor 6 is high. As shown in FIG. 7, a pulsation component having a frequency corresponding to the initial speed ωm0 of the electric motor 6 is superimposed on the current i flowing through the electric motor 6. Thus, the current i cannot be controlled to the direct current as commanded. In FIG. 7, i _A and i _B are the A and B axis components of the vector i.

Then, the actual magnetic flux vector φ2r of the electric motor 6 does not become the equation (H) assuming a direct current, and the radius of the locus of the actual magnetic flux vector φ2r decreases rapidly as shown in FIG. F2rA and F2rB in FIG. 8 are the A and B axis components of the actual magnetic flux vector φ2r obtained by the equation (A) . In the calculation using the equations (B) to (G), the influence of the estimation error of the actual magnetic flux estimation unit 9 increases as the vectors F1 and F2 become smaller. As a result, the calculation accuracy deteriorates. A large error may occur in the estimation of the initial speed ωm0 and the initial secondary magnetic flux φ20.

  Here, by increasing the control gain of the pick-up control unit 2, the control delay can be improved, and the amplitude of the pulsating component of the current i flowing through the electric motor 6 is reduced. However, if the control gain is uniformly increased, the control may become unstable when the initial delay ωm0 of the electric motor 6 is low because the control delay is not originally large.

  The present invention has been made to solve the above-described problems, and is a speed at which the initial speed ωm0 and the initial secondary magnetic flux φ20 of the motor can be estimated with high accuracy without fear of unstable control. An object of the present invention is to provide a sensorless motor control device.

To solve the above problem, the speed sensorless motor control apparatus of the present invention includes a current detector for detecting current vector flowing through the electric motor, the direct current finger Ryo及 beauty based on a plurality of direct current phase angle command, the current vector outputs a voltage command for controlling said plurality of direct current phase angle command of each of the DC current, picked the plurality of variable gain picked with switching control to output the voltage command as the selected picked voltage command one by the control switching command A real magnetic flux estimation unit that inputs the current vector and the pick-up voltage command and outputs a real magnetic flux vector, and inputs the current vector, the real magnetic flux vector, and the pick-up time, and the initial speed and initial value of the motor An initial value estimation unit that outputs a secondary magnetic flux, and at least one of the actual magnetic flux vector and the DC phase angle command are input, An arithmetic unit for outputting a control switching command, characterized in that it comprises a.

  Preferably, the pick-up control unit with variable gain switching is a first for controlling the current vector to the first DC current based on the DC current command, the DC phase angle command, and the first control gain. A first current control unit that outputs a pick-up voltage command, and a second pick-up voltage for controlling the current vector to a second DC current based on the DC current command, the DC phase angle command, and a second control gain A second current control unit that outputs a command; and a command switching unit that switches the first pick-up voltage command and the second pick-up voltage command according to the pick-up control switching command to set the pick-up voltage command.

  Preferably, the DC phase angle command input to the second current control unit is set to a value different from the DC phase angle command input to the first current control unit. More preferably, the DC phase angle command input to the second current control unit is set to a value obtained by inverting the phase by 180 degrees from the DC phase angle command input to the first current control unit.

Here, preferably, the calculation unit further inputs the pick-up time, further outputs a provisional estimated speed of the electric motor calculated from the pick-up time and the actual magnetic flux vector, and pick-up with the variable gain switching At least one control gain of a plurality of controls of the control unit is based on the provisional estimated speed.

  By the above means, without making the control unstable, even when the initial speed of the motor is high, the current flowing through the motor can be controlled to a direct current to suppress a rapid decrease in the radius of the locus of the actual magnetic flux vector. As a result, the initial speed and initial secondary magnetic flux of the electric motor can be estimated with high accuracy, and the torque of the electric motor can be controlled with high accuracy.

It is a block diagram which shows one structural example of the speed sensorless electric motor control apparatus of this invention. It is a block diagram which shows one structural example of the pick-up control part with a variable gain switch of this invention. It is a graph which shows the locus | trajectory of the real magnetic flux vector of one structural example of the speed sensorless electric motor control apparatus of this invention. It is a figure which shows the locus | trajectory of the actual magnetic flux vector of an electric motor at the time of operating one Embodiment of the speed sensorless electric motor control apparatus of this invention. It is a block diagram which shows the example of 1 structure of the conventional speed sensorless electric motor control apparatus. It is a block diagram which shows the example of 1 structure of the conventional initial value estimation part. It is a figure which shows the time transition of each component of the electric current vector of an electric motor, and an actual magnetic flux vector at the time of operating the conventional speed sensorless electric motor control apparatus. It is a graph which shows the locus | trajectory of the real magnetic flux vector of the conventional speed sensorless electric motor control apparatus.

  Even when the initial speed of the motor is high without making the control unstable, a configuration capable of controlling the current flowing through the motor to DC is realized.

  FIG. 1 is a block diagram showing a configuration example of the present invention. The speed sensorless motor control device of the present embodiment includes a torque control unit 1, a switching unit 3, a power conversion unit 4, a current detection unit 5, an initial value estimation unit 7, an actual magnetic flux estimation unit 9, and a calculation unit. A timer 14, a calculation unit 101, and a pick-up control unit 102 with variable gain switching are provided. In addition, about the component similar to the prior art shown in FIG.5, 6 mentioned above, the same code | symbol as FIG.5, 6 is attached | subjected and description is abbreviate | omitted.

  The pick-up control unit 102 with variable gain switching is based on the current vector i of the motor 6 and the DC current command I, at least one (two in this embodiment) DC phase angle commands θ1 and θ2, and the control gain. It is possible to control i to be a direct current having at least one (two in this embodiment) phase angle. A plurality of controls are switched by a pickup control switching command SS, and a pickup voltage command v0 is output.

  The calculation unit 101 receives the actual magnetic flux vector φ2r and at least one DC phase angle command θ1, and outputs a pick-up control switching command SS.

  The pick-up control switching command SS can be obtained by various methods. In the first example, when the pick-up time t0 output by the calculation timer 14 reaches a predetermined value, the calculation unit 101 turns on the pick-up control switching command SS.

  In the second example, the calculation unit 101 turns on the pick-up control switching command SS when the maximum value of the component perpendicular to the DC phase angle command θ1 of the actual magnetic flux vector φ2r is detected.

  The pick-up control switching command SS is input to the arithmetic timer 14, and the pick-up time t0 is cleared to 0 at the edge when the pick-up control switching command SS is turned on from off.

  In this embodiment, the calculation unit 101 inputs the pick-up time t0 and the actual magnetic flux vector φ2r, and further outputs the provisional estimated speed ωma of the electric motor 6.

  The number of times that the maximum value and the minimum value of the component perpendicular to the DC phase angle command θ1 of the actual magnetic flux vector φ2r from the time when the arithmetic timer 14 is cleared to the pick-up time t0 is N, and N is the pick-up time From the ratio with t0, the provisional estimated speed ωma [Hz] can be calculated by the equation ωma = N / (2 · t0). The maximum value of the component of the actual magnetic flux vector φ2r that is orthogonal to the DC phase angle command θ1 can be detected, for example, by detecting that the component has changed from monotonically increasing to monotonically decreasing.

  In the speed sensorless electric motor control device of this embodiment, the pick-up control switching command SS is created according to the state of the actual magnetic flux vector φ2r, and the DC current control state of the pick-up control can be switched by the pick-up control switching command SS.

  FIG. 2 is a block diagram showing a configuration example of the pick-up control unit 102 with variable gain switching shown in FIG. The pick-up control unit 102 with variable gain switching includes a first current control unit 103, a second current control unit 104, a second control gain calculation unit 105, and a command switching unit 106.

  The first current control unit 103 is a first for controlling the current vector i flowing through the electric motor 6 to the first DC current based on the DC current command I, the first DC phase angle command θ1, and the first control gain IG1. A pick-up voltage command v01 is output.

  The second control gain calculation unit 105 calculates the second control gain IG2 based on the first control gain IG1 and the provisional estimated speed ωma of the electric motor.

  The second control gain IG2 can be obtained by various methods. In the first example, the speed threshold value is ωmb, and IG2 = IG1 when ωma <ωmb. On the other hand, when ωma ≧ ωmb, IG2 = IGG · IG1. The proportionality constant IGG is a constant larger than 1. That is, if the provisional estimated speed ωma is higher than the speed threshold ωmb, the control gain IG2 is larger than the control gain IG1.

にてＩＧ２を演算する。この場合には、暫定推定速度ωｍａが大きくなるとともに、第２制御ゲインＩＧ２が大きくなる。この実施形態では、オフセット定数ＯＩＧは約１とする。 In the second example, using the proportionality constant GIG and the offset constant OIG, the equation

To calculate IG2. In this case, the provisional estimated speed ωma increases and the second control gain IG2 increases. In this embodiment, the offset constant OIG is about 1.

  The second current control unit 104 controls the current vector i flowing through the electric motor 6 to the second DC current based on the DC current command I, the second DC phase angle command θ2, and the second control gain IG2. 1 Pickup voltage command v02 is output.

  The command switching unit 106 outputs the first pickup voltage command v01 as the pickup voltage command v0 when the pickup control switching command SS is OFF. When the pickup control switching command SS is on, the second pickup voltage command v02 is output as the pickup voltage command v0.

  With the above configuration, when the provisional estimated speed ωma of the electric motor 6 is large, that is, when the initial speed of the electric motor 6 is high, the control gain of the second current control unit 104 becomes large. While the rounding-up control switching command SS is off, the control gain of the pick-up control unit 102 with variable gain switching is a small first control gain, so that the control delay increases, and the current vector i is set to the initial speed of the motor 6. Frequency pulsations may be superimposed. Even in this case, when the rounding-up control switching command SS is turned on, the control gain of the pick-up control unit 102 with variable gain switching becomes a larger second control gain, so that the control delay is reduced, and the current flowing through the motor is changed to DC. Can be controlled.

  When the initial speed of the motor is high, the control delay tends to increase as described above, so that the control becomes unstable even if the control gain of the pick-up control unit 102 with variable gain switching is increased. There is no fear.

  On the other hand, when the initial speed of the motor is low, the control gain IG2 of the second current control unit 104 does not increase, and the control gain of the pick-up control unit 102 with variable gain switching does not increase. Therefore, there is no possibility that the control becomes unstable. Even if the control gain of the pick-up control unit 102 with variable gain switching is small, the control delay does not increase, and the current flowing through the motor can be controlled to DC.

  Therefore, regardless of whether the initial speed of the motor 6 is low or high, the locus of the actual magnetic flux vector φ2r of the motor 6 is as shown in FIG. 3, and the radius hardly changes. Therefore, in the calculation using the equations (B) to (G), the magnitudes of the vectors F1 and F2 are increased, and the influence of the estimation error of the actual magnetic flux estimation unit 9 is reduced. As a result, the initial speed and the initial secondary magnetic flux of the electric motor 6 can be estimated with higher accuracy. Moreover, there is no possibility that the control becomes unstable regardless of whether the initial speed of the electric motor 6 is low or high.

  By the way, when there is a residual magnetic flux φxx in which the absolute value in the parenthesis is small in the second term of the formula (H), the calculation using the formulas (B) to (G) is the magnitude of the vectors F1 and F2. Therefore, the influence of the estimation error of the actual magnetic flux estimation unit 9 is increased. As a result, the calculation accuracy is deteriorated, and there is a possibility that an error occurs in the estimation of the initial speed ωm0 and the initial secondary magnetic flux φ20 of the electric motor 6.

  Also, even if the residual magnetic flux φxx is sufficiently small, such as after a period of time after use of the motor, if the initial speed of the electric motor to be estimated is high, the absolute value in parentheses in the second term of equation (H) Becomes smaller. In this case as well, the calculations using the equations (B) to (G) are less accurate because the magnitudes of the vectors F1 and F2 are small, and the initial speed ωm0 and the initial secondary magnetic flux φ20 are estimated. An error may occur.

  Thus, particularly when there is residual magnetic flux or when the initial speed of the motor 6 is high, errors occur in the estimated values of the initial speed ωm0 and the initial secondary magnetic flux φ20, and as a result, the initial input of the torque control unit 1 is generated. Since there is an error in the value, there is a possibility that the torque control of the electric motor 6 cannot be performed with high accuracy. Here, if the DC power command I is increased, the absolute value in the parenthesis of the second term of the formula (H) can be increased, but in that case, the behavior of the motor 6 may be affected.

  Here, from the viewpoint of reducing errors in the estimated values of the initial speed ωm0 and the initial secondary magnetic flux φ20 of the electric motor 6, the second DC phase angle command θ2 may be set to a value different from the first DC phase angle command θ1. preferable. More preferably, the second DC phase angle command θ2 is set to a value obtained by inverting the first DC phase angle command θ1 by 180 degrees from the viewpoint of reliably reducing the error.

  With this configuration, the following pickup control can be realized. In order to simplify the description, the first DC phase angle command θ1 is 0 °, and the second DC phase angle command θ2 is 180 °. That is, the first current control unit 103 controls the current vector i to the first DC current (I, 0), and the second current control unit 104 controls the current vector i to the second DC current (−I, 0). .

  The pick-up control unit 102 with variable gain switching starts pick-up control from a state in which the pick-up control switching command SS is off. The time at this time is set to 0. Since the first pick-up voltage command v01 is output as the pick-up voltage command v0, the current vector i is controlled to the first DC current (I, 0). The locus of the actual magnetic flux vector φ2r of the electric motor 6 until the pickup control is started and the pickup control switching command SS is turned on is indicated by an arc C1 shown in FIG.

Arithmetic unit 101 turns on pick-up control switching command SS when it detects the maximum value of the component orthogonal to first DC phase angle command θ1 of actual magnetic flux vector φ2r. Since θ1 is set to 0 ° this time, it is picked up at time t ₁ when the imaginary axis (B-axis) component of the real magnetic flux vector φ2r is maximum, that is, when the locus of φ2r intersects the positive side of the B-axis in FIG. The control switching command SS is turned on.

Thereafter, since the second pick-up voltage command v02 is output as the pick-up voltage command v0, the current vector i is controlled to the second DC current (−I, 0). The locus of the actual magnetic flux vector φ2r after the pickup control switching command SS is turned on is indicated by an arc C2 shown in FIG. In the locus of the arc C2, φ (t ₁ ) is the residual magnetic flux φxx shown in the equation (H). Therefore, if the radius of the arc C1 is r, the radius of the arc C2 is r + φ (t ₁ ). Therefore, by switching the pick-up voltage command SS as described above, without increasing the DC current command I, the radius of the arc drawn by the actual magnetic flux vector φ2r, that is, the absolute value in parentheses in the second term of the equation (H) To increase the error of the estimated values of the initial speed ωm0 and the initial secondary magnetic flux φ20 of the electric motor 6.

  According to the present invention, the current i can be controlled to a direct current without causing control instability, and a sudden decrease in the radius of the circular locus of the actual magnetic flux vector can be prevented. As a result, the initial speed and initial secondary magnetic flux of the motor can be estimated with high accuracy, and the motor torque can be controlled with high accuracy.

  Further, by devising how to give the DC phase angle command, it is possible to estimate the initial speed and the initial secondary magnetic flux of the motor with high accuracy without increasing the DC current command I.

DESCRIPTION OF SYMBOLS 1 Torque control part 2 Pickup control part 3 Switching part 4 Power conversion part 5 Current detection part 6 Electric motor 7 Initial value estimation part 9 Real magnetic flux estimation part 10 Real magnetic flux memory 11 Actual magnetic flux extraction part 12 Initial speed estimation part 13 Initial magnetic flux estimation part 13 DESCRIPTION OF SYMBOLS 14 Calculation timer 101 Calculation part 102 Pickup control part with variable gain switching 103 1st current control part 104 2nd current control part 105 2nd control gain calculation part 106 Command switching part

Claims (5)

A current detector for detecting a current vector flowing in the electric motor;
The direct current finger Ryo及 beauty based on a plurality of direct current phase angle command, the current vector output a voltage command for controlling said plurality of direct current phase angle command of each of the DC current, the plurality of the control switching command picked A pick-up control unit with variable gain switching for selecting one of the voltage commands and outputting it as a pick-up voltage command;
An actual magnetic flux estimation unit that inputs the current vector and the pick-up voltage command and outputs an actual magnetic flux vector;
An initial value estimation unit that inputs the current vector, the actual magnetic flux vector, and the pick-up time, and outputs an initial speed and an initial secondary magnetic flux of the motor;
An arithmetic unit that inputs at least one of the actual magnetic flux vector and the DC phase angle command, and outputs the pickup control switching command;
A speed sensorless motor control device comprising: The pick-up control unit with variable gain switching is
A first current control unit that outputs a first pick-up voltage command for controlling the current vector to a first DC current based on the DC current command, the DC phase angle command, and a first control gain;
A second current control unit that outputs a second pick-up voltage command for controlling the current vector to a second DC current based on the DC current command, the DC phase angle command, and a second control gain;
A command switching unit that switches the first pick-up voltage command and the second pick-up voltage command by the pick-up control switching command to be the pick-up voltage command;
The speed sensorless motor control device according to claim 1, comprising:   The speed sensorless motor control device according to claim 2, wherein the DC phase angle command input to the second current control unit is set to a value different from the DC phase angle command input to the first current control unit. .   The speed sensorless system according to claim 3, wherein the DC phase angle command input to the second current control unit is set to a value obtained by reversing the DC phase angle command input to the first current control unit by 180 degrees. Electric motor control device.   The calculation unit further inputs the pick-up time, further outputs a provisional estimated speed of the motor calculated from the pick-up time and the actual magnetic flux vector, and a plurality of controls of the pick-up control unit with variable gain switching 5. The speed sensorless motor control device according to claim 1, wherein at least one control gain is based on the provisional estimated speed. 6.

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