JP5854057B2 - Step-out detection device and motor drive system - Google Patents

Description

  The present invention relates to a step-out detection device and an electric motor drive system.

  Non-Patent Documents 1 and 2 describe a method for controlling a synchronous motor. The synchronous motor has an armature having windings and a field. In Non-Patent Documents 1 and 2, the primary magnetic flux of the synchronous motor is controlled. More specifically, the γ-axis and δ-axis that are orthogonal to each other are adopted as the control axes, and the γ-axis component of the primary magnetic flux is controlled to zero.

  Patent documents 1 to 3 are presented as techniques related to the present application.

JP 2000-197397 A JP 2008-125264 A Japanese Patent Laid-Open No. 9-294390

Kaku, Yamamura, Tsunehiro, “Position Sensorless Control Method for DC Brushless Motor”, IEEJ Transactions D, 1991, Vol. 111, No. 8, p.639-644 Hamada, Yamamura, Tsunehiro, "General-purpose inverter for driving synchronous machines", IEEJ Transactions D, 1999, Vol.119, No.5, p.707-712

  It is desired to detect that the motor has stepped out. Therefore, it is conceivable to calculate the phase angle between the δ-γ rotating coordinate system having the δ axis and the γ axis and the dq rotating coordinate system having the d axis in phase with the flux linkage caused by the field of the electric motor. . Then, a phase angle range in which the motor rotates without stepping out is set in advance, and stepping out is detected when the phase angle exceeds the range.

  However, the calculation of the phase angle requires an inverse trigonometric function, as will be described in detail later. Such inverse trigonometric functions are complex to compute.

  Therefore, an object of the present invention is to provide a step-out detection device that detects step-out without the need to calculate a phase angle.

A step-out detection apparatus according to a first aspect of the present invention includes a motor (2) having a field (23) and an armature (21) including an armature winding (22), and a voltage applied to the motor. In the electric motor drive device having a drive device (1) that outputs a phase difference with respect to the d-axis in phase with the interlinkage magnetic flux to the armature by the field. _{Obtains the} current ([i _δγc ]) that flows through the armature winding in a rotational coordinate system having a _δc axis that forms an angle (φc) and a γc axis whose phase is 90 degrees in the first direction with respect to the _{δc axis} . A current acquisition unit (5, 34) that performs, a rotation speed calculation unit (32) that calculates a rotation speed (ω1) of a rotation coordinate having the δc axis and the γc axis, and the armature winding in the rotation coordinate lines applied voltage or command a is acquired voltage thereof ([V ^*]) AC voltage acquiring unit for acquiring (35), the rotating seat In the voltage equation of the electric motor in FIG. 1, the range of the phase angle when the electric motor rotates without being out of step is derived, does not include the phase angle, and the current, the rotational speed, and the voltage are variables. And a determination unit (4) for determining whether or not the out-of-step determination inequality included as follows is satisfied, and detecting the out-of-step determination of the electric motor when the out-of-step determination inequality is not satisfied.

A second aspect of the step-out detection apparatus according to the present invention is the step-out detection apparatus according to the first aspect, wherein the range of the phase angle (φc) is −x (x is 0 degree or more and 180 degrees). a range of not less than x degrees degrees below), among the voltage equation, the voltage _{([V δγc])} to the voltage equation for component (V _{[gamma] c)} of the [gamma] c-axis, the cosine value of the phase angle ( cosφc) is included as a term, and the determination unit (4) is derived by _{modifying the} voltage equation for the γc-axis component of the voltage to indicate the cosine value, and the current ([i _δγc )), The rotational speed (ω1), the γc-axis component of the voltage as a variable, and an equivalent expression including the resistance value and the inductance as device constants is determined according to the range of the phase angle When the value is smaller than the value, the step-out is detected.

A third aspect of the step-out detection apparatus according to the present invention is the step-out detection apparatus according to the second aspect, wherein the upper limit value and the lower limit value of the range of the phase angle (φc) are −90 degrees and 90 degrees, and the resistance value and inductance of the armature winding, the rotation speed, the γc-axis component of the voltage, the γc-axis component and the δc-axis component of the current are R, Lq, ω1, V _γc , i _γc and i _δc , the rotation speed is positive when the rotation direction of the electric motor is the first direction, and the rotation when the rotation direction is opposite to the first direction. assuming that the speed is negative, the determination unit (4), when the positive and negative polarities of formula _{V γc -R · i γc -ω1 ·} Lq · i δc is different from the positive and negative polarities of the rotational speed, the Detect step-out.

A fourth aspect of the step-out detection device according to the present invention is the step-out detection device according to the third aspect, wherein the determination unit (4) is configured such that when the rotation direction is the first direction, As the value of the resistance value, among the upper limit value and the lower limit value of the range in which the resistance value fluctuates in the manufacturing tolerance and operating temperature guaranteed range of the electric motor, the one having the larger value R · i _γc is adopted, When the rotation direction is opposite to the first direction, the smaller value R · i _γc is adopted, and the inductance value is within the guaranteed range of manufacturing tolerance and operating temperature of the motor. Of the upper limit value and the lower limit value of the range in which the value fluctuates, the one with the larger value Lq · i _δc is adopted.

A fifth aspect of the step-out detection device according to the present invention is the step-out detection device according to the second aspect, wherein the field (23) is a field having a reverse saliency, and the armature The upper and lower limits of the range in which the resistance value of the winding fluctuates within the manufacturing tolerance and operating temperature guaranteed range of the motor, the d-axis component of the inductance of the armature winding, and the d-axis with respect to the d-axis The q-axis component advanced by 90 degrees in one direction is the upper and lower limits of the range that fluctuates within the guaranteed range of manufacturing tolerance and operating temperature of the motor, the rotational speed, the γc-axis component of the voltage, the current each components and components of the .delta.c axis of the [gamma] c _{axis, R min, R max, Ld} min, Ld max, Lq min, Lq max, ω1, and V _{[gamma] c,} i _{[gamma] c} and i _.delta.c, the rotational direction of the electric motor Is the first direction The rotation speed is positive when the rotation direction is negative, and the rotation speed is negative when the rotation direction is opposite to the first direction. When x> 0, sgn (x) = 1, x <0 When sgn (x) = − 1, max [a, b] = a when a> b, and max [a, b] = b when a <b, the determination unit (4) _{V γc · sgn (ω1) -max} [R min · i γc · sgn (ω1), R max · i γc · sgn (ω1)] - | ω1 | · max [Ld min · i δc, Lq max · i δc _{] - | ω1 | · (Lq} min -Ld max) / 2 · max [i γc, when -i _{[gamma] c]} is negative, detects the step-out.

  An aspect of an electric motor drive system according to the present invention includes a step-out detection device according to any one of the first to fifth aspects, the electric motor, and the drive device.

  According to the first aspect of the step-out detection apparatus and the aspect of the motor drive system according to the present invention, the step-out discrimination inequality does not include the phase angle. Need not be calculated. Therefore, the calculation can be facilitated as compared with the case where the phase angle is calculated and it is determined whether or not the phase angle is within the range and the step-out is detected.

  According to the second aspect of the step-out detection device of the present invention, as described in detail in the embodiment, the step-out discriminant using the sine value (sin (φc)) of the phase angle (φc) is calculated. Compared with the case of using, discrimination can be made easily.

According to a third aspect of the out-detecting apparatus according to the present invention, the cosine value of the phase _{angle, (V γc -R · i γc} -ω1 · Lq · i δc) / (ω1 · Λ0) (Λ0 the chain According to claim 3, it is not necessary to use division with (ω1 · Λ0) as the denominator. Therefore, calculation can be facilitated.

  According to the fourth aspect of the step-out detection device of the present invention, even when there is a risk of step-out, it can be detected that step-out is present.

  According to the fifth aspect of the step-out detection device of the present invention, the variation in resistance value in manufacturing or physical properties, the variation amount depending on the variation in inductance manufacturing or physical properties, and the rotation direction of the motor are taken into consideration. Thus, the resistance value and the inductance are adopted so that the value of the equation becomes the smallest. Therefore, even if there are variations in manufacturing or physical properties, step-out can be detected.

It is a figure which shows an example of a rotation coordinate and a magnetic flux typically. It is a figure which shows an example of the fluctuation | variation of an inductance. It is a figure which shows an example of a notional structure of a power converter device.

  Prior to the detailed description of the embodiments, the basic idea of the present invention will be described. Of course, this basic idea is also within the scope of the present invention.

<1. Basic Thought>
FIG. 1 shows a synchronous motor (hereinafter, simply referred to as “motor”. As a special type of synchronous motor, there is a motor that does not have a field such as a switched reluctance motor. Air gap magnetic flux [λ] (symbol [] represents a vector quantity; the same applies hereinafter) and interlinkage magnetic flux [Λ0] (hereinafter referred to simply as “linkage”) to the armature by the field. It is a vector diagram showing the relationship with "magnetic flux". For example, when the motor has a permanent magnet, the linkage flux [Λ0] is generated by the permanent magnet, and when the motor has a field winding, a current flows through the field winding. Generated by flowing.

  A dq rotating coordinate system is introduced as a rotating coordinate system synchronized with the rotation of the electric motor. Here, the d-axis is set in phase with the flux linkage [Λ0], and the q-axis advances 90 degrees with respect to the d-axis in a predetermined advance direction.

  Further, a δ-γ rotating coordinate system and a δc-γc rotating coordinate system are introduced as rotating coordinate systems. The phase advances at a phase angle φ in the advance direction with respect to the δ axis with respect to the d axis and the γ axis with respect to the q axis, respectively. The phase advances at a phase angle φc in the advance direction with respect to the d axis and the γc axis with respect to the q axis, respectively. Hereinafter, for convenience of explanation, the phase angle φ of the δ axis with respect to the d axis is referred to as an actual phase angle φ, and the phase angle φ of the δc axis with respect to the q axis is referred to as an estimated phase angle φc.

For example, in a motor control method known as “primary magnetic flux control”, the δ axis is set in phase with the gap magnetic flux [λ]. In this case, the actual phase angle φ is grasped as a load angle (phase angle between the interlinkage magnetic flux [Λ0] and the gap magnetic flux [λ]). The gap magnetic flux [λ] is also referred to as a primary magnetic flux, and the flux of the armature reaction generated by the interlinkage magnetic flux [Λ0] and the armature current (this is also the three-phase current [i _x ]) flowing through the armature. Is a synthesis of

As is well known, the gap magnetic flux [λ] is a voltage and current supplied to an electric motor (more specifically, an armature winding included in an armature included in the electric motor) and device constants (for example, inductance, armature) of the electric motor. The resistance value of the resistance component of the winding, the flux linkage) and the rotational speed of the motor. Therefore, the estimated value [λ ^] of the air gap magnetic flux [λ] is obtained from the measured values (or command values, estimated values) of the voltage and current, the device constants, and the rotation speed. Therefore, the control device that controls the electric motor performs control so that the estimated value [λ ^] is equal to the command value [λ ^* ] of the air gap magnetic flux [λ]. In the “primary magnetic flux control” described above, the γ-axis component of the command value [λ ^* ] is zero.

When the δc-γc rotational coordinate system is employed in such control, the estimated phase angle φc matches the actual phase angle φ, so that the rotation of the motor can be appropriately controlled. If the device constant, rotational speed, voltage and current applied to the motor are fully understood, the estimated value [λ ^] obtained based on these is controlled to be equal to the command value [λ ^* ]. This is because the gap magnetic flux [λ] matches the command value [λ ^* ].

  For example, in the primary magnetic flux control, the speed control is performed in the range of the actual phase angle φ where the generated torque monotonously increases with respect to the actual phase angle φ. For example, in a surface magnet synchronous motor, control is performed in the range where the actual phase angle φ is in the range of −90 degrees to 90 degrees. However, due to load fluctuations, disturbances, etc., the motor may not rotate properly and may step out. At this time, for example, in the surface magnet synchronous motor, the estimated phase angle φc does not fall within the range of −90 degrees to 90 degrees.

  The present invention pays attention to this point, and derives a step-out determination inequality for determining the presence or absence of step-out in consideration of the range of the estimated phase angle in which the electric motor rotates appropriately without step-out. And it intends to detect a step-out using this.

  Here, since the control is performed in the δc-γc rotating coordinate system, the voltage equation in the δc-γc rotating coordinate system is considered in deriving the step-out discrimination inequality. This voltage equation is expressed by the following equation.

_Here, [V _δγc] is, .delta.c-axis component of the voltage applied to the motor (hereinafter, also referred to as a voltage V _.delta.c) and [gamma] c-axis component (hereinafter, also referred to as a voltage V _{[gamma] c)} a voltage vector having, [V _δc V _γc ] ^t (the superscript “t” indicates transposition of the matrix). R is the resistance value of the resistance component of the armature winding. _[I δγc] is, .delta.c-axis component of the current flowing in the armature winding (hereinafter, current i _.delta.c also called) and [gamma] c-axis component (hereinafter, also referred to as a current i _{[gamma] c)} a current vector having, [i _.delta.c i _[gamma ] _c ] ^t . p represents a differential operator, and ω1 represents a rotation speed. The rotational speed ω1 is positive when the electric motor rotates in the advance direction (forward rotation direction), and is negative when the electric motor rotates in the direction opposite to the advance direction. _[Λ δγc] is a magnetic flux vector with .delta.c axis component lambda _.delta.c and [gamma] c-axis component lambda _{[gamma] c} of the air-gap flux [lambda], can be expressed as [λ _δc λ _γc] ^t. Ld and Lq are a d-axis component (hereinafter also referred to as d-axis inductance) and a q-axis component (hereinafter also referred to as q-axis inductance) of the inductance of the armature winding, respectively. The linkage flux Λ0 is the magnitude (scalar amount) of the linkage flux [Λ0]. However, [I], [J] and the symbol [] surrounding these elements indicate a matrix.

  The voltage equation shown above is derived by performing rotational conversion of the estimated phase angle φc with respect to the voltage equation in the well-known dq rotation coordinate system.

This voltage equation includes a voltage [V _δγc ], a current [i _δγc ], a rotational speed ω1 and an estimated phase angle _φc as variables, and includes a resistance value R, a d-axis inductance Ld, a q-axis inductance Lq, and an interlinkage flux Λ0. Included as a motor constant. The value of the device constant is appropriately acquired as an actually measured value, an estimated value, or a predetermined set value, and the variable is appropriately acquired as an actually measured value, an estimated value, or a command value (a detailed example will be described later). By acquiring these pieces of information, the only unknown in the voltage equation is the estimated phase angle φc, so that the estimated phase angle φc can be calculated based on the voltage equation. However, in the present embodiment, the estimated phase angle φc is not calculated for step-out detection.

  Now, the range of the estimated phase angle φc when the electric motor rotates without being out of step can be expressed by, for example, the following expression (however, the expression of φc was made at −180 ° <φc <180 °).

  Since there exist voltage equations (equations (1) and (2)) including the estimated phase angle φc and an inequality (equation (3)) indicating the range of the estimated phase angle φc, based on these equations, As will be described in detail, an inequality (step-out discrimination inequality) that does not include the estimated phase angle φc can be derived. In this embodiment, the device constant and the variable are acquired to determine whether or not the out-of-step determination inequality is satisfied. When the out-of-step determination inequality is not satisfied, the out-of-step is detected. It is. A detailed example will be described below.

<2. Non-salience motor>
<2-1. Step-out detection using step-out discrimination inequality>
First, an electric motor having no saliency (in other words, having non-saliency) will be described. In the motor having non-saliency, the inductance is isotropic by definition, so that the d-axis inductance Ld and the q-axis inductance Lq are equal to each other. Therefore, here, the symbol Lq is used as a notation of the inductance of the armature winding of the motor having non-saliency. As such an electric motor, the electric motor (surface magnet synchronous motor) which employ | adopted the field which has a core and the permanent magnet provided over the outer periphery of a core can be illustrated.

Considering Ld = Lq, L0 = Ld = Lq and L1 = 0. For the sake of simplicity, the voltage equation is expressed by the following equation when the term indicated by the differential operator p is approximated to zero assuming a steady state. Expressions (5) and (6) express Expression (4) for each of the voltages V _δc and V _γc .

If the motor has not stepped out, the estimated phase angle φc is in the range of −90 degrees to 90 degrees (formula (3)). Therefore, the cosine value (cos φc) of the estimated phase angle φc is zero or more. Referring to equation (6), the voltage equation for the voltage V _{[gamma] c} present cosine value (Cosfaishi) is. Thus by modifying the voltage equation for the voltage V _{[gamma] c,} leads to equivalent expression indicating the cosine value (cosφc) as follows.

  Since the cosine value (cosφc) is greater than or equal to zero, the following inequality is derived.

This equation (8) is adopted as a step-out discrimination inequality. In equation (8), the values of the device constants (resistance value R, inductance Lq, linkage flux Λ0) are determined in advance, for example. Therefore, the values (measured values, command values, or estimated values) of the variables (voltage V _γc , current i _δc , i _γc , rotation speed ω 1) are acquired, and it is determined whether or not this step-out determination inequality is satisfied. To do. When it is determined that the step-out determination inequality is not satisfied, it is determined that step-out has occurred. In other words, it is determined that the step-out has occurred when the equivalent expression (the left side of Expression (8)) indicating the cosine value (cos φc) is smaller than zero.

  It should be noted that the above-described variables are repeatedly acquired at predetermined timings, and each time it is determined whether or not the step-out determination inequality is satisfied. Thereby, step-out can be detected during the entire operation of the electric motor.

  As described above, according to the present embodiment, step-out is detected using a step-out discrimination inequality (for example, Equation (8)) that does not include the estimated phase angle φc. Therefore, it is not necessary to perform an inverse trigonometric function calculation (for example, arc cosine) for calculating the estimated phase angle φc. Therefore, the arithmetic processing can be facilitated.

  Equation (8) includes division with (ω1 · Λ0) as the denominator. Division processing is more complicated than the other four arithmetic operations. Therefore, a step-out discrimination inequality that does not use division with (ω1 · Λ0) as the denominator is derived below.

  When sgn (x), which takes 1 when x> 0 and -1 when x <0, is introduced into equation (8), the following equation is derived.

  Since (| ω1 | · Λ0) of the denominator in Equation (9) is positive, multiplying both sides of Equation (9) by (| ω1 | · Λ0), the following equation can be derived.

  If Expression (10) is adopted as a step-out discrimination inequality, there is no need to perform division with (ω1 · Λ0) as the denominator. Therefore, the arithmetic processing can be further facilitated.

Note that step-out detection using equation (10) can also be explained as follows. That is, when the positive and negative polarities of the formula _{(V γc -R · i γc -ω1} · Lq · i δc) is different from the polarities of positive and negative rotational speed .omega.1, detects the step-out can Tomo explained.

  Even if the estimated phase angle φc is in the range of −90 degrees to 90 degrees, step-out may occur when taking a value in the vicinity of ± 90 degrees. This is because, for example, the estimated phase angle φc does not always coincide with the actual phase angle φ. Therefore, a narrower range (for example, a range of −80 degrees to 80 degrees) may be adopted as the range of the estimated phase angle φc.

  Thus, when the range of -80 degrees to 80 degrees is adopted as the range of the estimated phase angle φc, the step-out discriminant is expressed by the following expression.

  In this case, it is necessary to calculate (| ω1 | · Λ0) as can be understood from the equation (11). Therefore, the calculation can be facilitated by adopting the formula (10) (that is, adopting 90 degrees and −90 degrees as the upper limit value and the lower limit value of the estimated phase angle φc, respectively).

  If the estimated phase angle φc is in the range of −80 degrees to 80 degrees, sin φc satisfies −0.9848 or more and 0.9848 or less. Therefore, it is conceivable that the equivalent equation of sin φc is obtained by modifying equation (5), and an inequality that satisfies sin (−80 °) or more and sin (80 °) or less is adopted as the step-out discriminant.

  When step-out occurs, the estimated phase angle φc increases from a positive value smaller than 90 degrees and exceeds 90 degrees, or the estimated phase angle φc decreases from a negative value larger than −90 degrees. , Below -90 degrees. Therefore, when step-out occurs, there is a period in which the equivalent expression of sin φc is less than sin (−80 °) or a period in which the equivalent expression of sin φc is more than sin (80 °). In these periods, the step-out discriminant in which the equivalent expression of sin φc is not less than sin (−80 °) and not more than sin (80 °) is not satisfied. Therefore, even if this step-out discriminant is used, step-out can be detected.

  However, in this step-out inequality, whether to determine whether the equivalent expression of sin φc falls below sin (−80 °) and whether to determine whether the equivalent expression of sin φc exceeds sin (80 °), Alternatively, it is necessary to calculate the absolute value of sin φ and determine whether or not it exceeds sin (80 °). On the other hand, if the equivalent expression of cos φc is used as in the expressions (9) to (11), the determination is performed once without calculating the absolute value. Therefore, discrimination can be simplified. More generally, (i) as a range of the estimated phase angle φc, a range in the range of −x (x is 0 degree or more and less than 180 degrees) degrees or more and x degrees or less is adopted, and (ii) When the value calculated using the equivalent equation of cos φc is smaller than the reference value determined according to the range of the estimated phase angle φc, the step-out may be detected. Thereby, discrimination can be made easily.

  Depending on the load of the synchronous motor 2, the synchronous motor 2 may be operated in a range where the load angle φ is, for example, 0 degrees or more and 90 degrees. That is, the upper limit value of the load angle φ and the absolute value of the lower limit value may be different. In this case, the determination may be performed as follows. First, as the range of the estimated load angle φc, for example, a (for example, 0) degree or more and b (for example, 90) degree or less is adopted. Then, a first determination is made as to whether or not the left side of equation (11), which is an equivalent equation of cos φc, exceeds cos (b). Further, a second determination is made as to whether or not the equivalent expression of sin φc derived using Expression (5) exceeds sin (a). Then, it may be determined that an abnormality has occurred in the synchronous motor 2 when a negative determination is made in at least one of the first determination and the second determination.

<2-2. Device constant>
As an example, a predetermined set value can be adopted as the resistance value R and the inductance Lq without using an actual measurement value or an estimated value. However, the resistance value R and the inductance Lq have variations in manufacturing or physical properties. For example, even if the temperature of each product is equal to each other, these values are different due to manufacturing variation (manufacturing tolerance), and even for the same product, the value varies depending on the temperature. That is, the resistance value R and the inductance Lq vary within the guaranteed range of manufacturing tolerance and operating temperature of the synchronous motor 2. Therefore, if a value such that the left side of Equation (10) is larger than the actual value (actually measured value) is adopted as the resistance value R and the inductance Lq, the step-out occurs. The step-out discrimination inequality may be satisfied. Such a case is not desirable.

  Therefore, a value that minimizes the left side of Equation (10) in the range of variations in the resistance value R and the inductance Lq is employed. This suppresses or avoids a decrease in the accuracy of step-out detection caused by variations.

First, the resistance value R will be described in detail. If the left side of Expression (10) is expanded and considered, the resistance value R is included only in the second term {−R · i _γc · sgn (ω1)} on the left side of Expression (10). When the values of other terms are fixed and considered, the left side of Equation (10) is the smallest when the second term is the smallest.

When the rotational speed ω1 is positive, sgn (ω1) is 1, and therefore the second term is represented by a value (−i _γc · R). The value (−i _γc · R) is proportional to the resistance value R with the value (−i _γc ) as a proportional coefficient. Therefore, when the current i _γc is positive, the value (−i _γc · R) is the smallest when the upper limit value R _max is adopted as the resistance value R, and when the current i _γc is negative. When the lower limit value R _min is adopted as the resistance value R, the resistance value R becomes the smallest. These upper limit value R _max and lower limit value R _min are set in advance in consideration of the range of variation of the resistance value R.

As described above, when the rotational speed ω1 is positive, the smaller value (−i _γc · R) of the upper limit value R _max and the lower limit value R _min may be adopted as the resistance value R. This is because the second term can be minimized. In other words, the higher value (R · i _γc ) of the upper limit value R _max and the lower limit value R _min may be adopted as the resistance value R.

On the other hand, when the rotational speed ω1 is negative, since sgn (ω1) is −1, the second term is represented by a value (i _γc · R). Therefore, in this case, the smaller value (R · i _γc ) between the upper limit value R _max and the lower limit value R _min is adopted as the resistance value R. Thereby, when the rotational speed ω1 is negative, the second term becomes the smallest.

Next, the inductance Lq will be described. Considering expand the left-hand side of equation (10), the inductance Lq is contained only in the third term of the left side _{{-ω1 · Lq · i δc ·} sgn (ω1)} of formula (10). Considering that ω1 · sgn (ω1) = | ω1 | is established, the third term can be expressed as a value {− | ω1 | · Lq · i _δc }. Therefore, if the value of the other term and the absolute value of the rotational speed ω1 are fixed and considered, the third term is the most when the value (Lq · i _δc ) is the largest regardless of the sign of the rotational speed ω1. As a result, the left side of Expression (10) becomes the smallest.

Therefore, as the inductance Lq, the one having the larger value (Lq · i _δc ) among the upper limit value Lq _max and the lower limit value Lq _min may be adopted. This is because the third term can be minimized at this time. These upper limit value Lq _max and lower limit value Lq _min are set in advance in consideration of the range of variation in inductance Lq.

  Here, max [a, b] is introduced to formulate the above contents to express the step-out discrimination inequality. This max [a, b] is a function that takes a when a is larger than b and takes b when a is smaller than b.

  As a result, it is possible to avoid a situation in which step-out cannot be detected despite step-out due to variations in manufacturing or physical properties.

  In the above-described example, variation in both the resistance value R and the inductance Lq is considered, but only one of them may be considered.

  In addition, when formula (11) is adopted instead of formula (10), the variation in the linkage flux Λ0 may be taken into consideration. The flux linkage Λ0 also varies within the guaranteed range of the manufacturing tolerance and the operating temperature of the synchronous motor 2, similarly to the resistance value R and the inductance Lq. Therefore, a value that minimizes the left side of Equation (11) in the range of variation of the linkage flux Λ0 is employed.

Considering the left side of the equation (11), the flux linkage Λ0 is included only in the denominator (| ω1 | · Λ0) of the equation (11). When the numerator on the left side of Equation (11) is positive, the left side is the smallest when the upper limit value Λ0 _max is adopted as the linkage flux Λ0, and when the numerator on the left side is negative, the linkage is It becomes the smallest when the lower limit Λ0 _min is adopted as the magnetic flux Λ0. The upper limit value Λ0 _max and the lower limit value Λ0 _min are set in advance in consideration of the range of variation of the linkage flux Λ0.

However, the right side of Expression (11) is positive. Therefore, when the left side of Expression (11) is negative, Expression (11) does not hold regardless of the value of the linkage flux Λ0. Therefore, when the left side is negative, it is determined that the step is out of step regardless of the flux linkage Λ0. Therefore, it is not necessary to consider the value of the flux linkage Λ0 when the left side is negative, and only the case where the left side is positive may be considered. Therefore, as the interlinkage magnetic flux Λ0, the upper limit value Λ0 _max may always be adopted regardless of the sign of the numerator on the left side. In other words, when the right side of Expression (11) is positive, the inequality does not hold if the left side is negative. Therefore, the upper limit value Λ0 _max may be adopted focusing only on the case where the left side is positive.

On the other hand, depending on the range of the estimated phase angle φc, the right side of Equation (11) may be negative. In this case, the inequality holds if the left side is positive. Therefore, the lower limit value Λ0 _min may be adopted by paying attention only to the case where the left side is negative. That is, the lower limit value Λ0 _min may always be adopted regardless of whether the numerator on the left side is positive or negative.

  As a result, it is possible to avoid a situation in which step-out cannot be detected despite step-out due to variations in manufacturing or physical properties.

  In addition, when employ | adopting Formula (10), since Formula (10) does not have linkage flux Λ0, it is not necessary to consider the dispersion | variation in linkage flux Λ0.

<3. Reverse saliency electric motor>
<3-1. Step-out detection using step-out discrimination inequality 1>
Next, a reverse saliency electric motor will be described. In a motor having a reverse saliency, by definition, the d-axis inductance Ld is smaller than the q-axis inductance Lq. As such an electric motor, for example, there is an electric motor adopting a field in which a part of a core is interposed between permanent magnets in the circumferential direction (more specifically, between poles). For example, an embedded magnet synchronous motor in which a permanent magnet is embedded in the core can be exemplified.

  Here, an inductance matrix [L (φc)] shown below is introduced.

This inductance matrix [L (φc)] is the same as the portion surrounded by the parentheses () on the right side of Equation (2), and is a matrix of 2 rows and 2 columns. In the following, each element of the inductance matrix [L (.phi.c)} as shown in equation (14), the value _{L δδ, L δγ, L γδ} , also expressed as _L γγ.

  For simplicity, assuming that a steady state is assumed in Equation (1), the term indicated by the differential operator p is approximated to zero, and the inductance matrix [L (φc)] is also used. It is represented by

Referring to equation (15), the voltage equation for the voltage V _{[gamma] c} it can be seen that the cosine value (Cosfaishi) is present. Thus, by modifying the voltage equation of the voltage V _{[gamma] c,} derived as follows equivalent expression indicating the cosine value (cosφc).

  Since the range of the estimated phase angle φc is, for example, not less than −90 degrees and not more than 90 degrees, the cosine value (cos φc) of the estimated phase angle φc is not less than zero. Therefore, the following inequality is derived.

In equation (17), the values L _δδ and L _δγ depend on the estimated phase angle _φc (see also equation (14)). FIG. 2 is a diagram illustrating an example of the values L _δδ and L _δγ . However, since the estimated phase angle _φc for step-out detection is not calculated _here , the values L _δδ and L _δγ are determined as follows.

As a first determination method, the estimated phase angle _φc is approximated to ± 90 degrees, and the values L _δδ and L _δγ are determined. The validity will be described next. When the estimated phase angle φc exceeds the range of −90 degrees or more and 90 degrees or less, the left side of Expression (17) is smaller than zero. Therefore, as the step-out detection, a case where the estimated phase angle φc is in the vicinity of 90 degrees or in the vicinity of −90 degrees may be considered. Therefore, here, the estimated phase angle φc is approximated to ± 90 degrees.

When _φc = ± 90 is substituted in the equation (14), the value L _{δδ matches} the q-axis inductance Lq (= L0−L1), and the value L _δγ matches zero, so the following inequality is derived.

  This is the same as equation (10).

  As simple step-out detection, d-axis inductance Ld or an average value (= L0) of d-axis inductance Ld and q-axis inductance Lq is used instead of q-axis inductance Lq in equation (18). You may do it.

<3-2. Step-out detection using step-out discrimination inequality 2>
As a second determination method, the values L _δδ and L _δγ are determined so that the left side of Expression (17) is _minimized . That is, a value that does not easily satisfy the step-out discrimination inequality is adopted. Thereby, it is suppressed that it is determined that there is no step out even though it is out of step.

First, consider the value L _δδ . Considering expand the left-hand side of equation (17), the value L _{.DELTA..delta} is included only in the equation the third term of the left side of _{(17) {-ω1 · L δδ} · i δc · sgn (ω1)}. When considering that holds, the third term, the value ω1 · sgn (ω1) = | | ω1 - represented by _{(| · L δδ · i δc} | ω1). Thus, when considered in fixing the value and the rotational speed .omega.1 of other terms, the third term, regardless of the sign of the rotational speed .omega.1, the value _(L δδ · i _δc) is smallest becomes when the largest As a result, the left side of the equation (17) becomes the smallest.

Value _(L δδ · _i δc) is proportional to the value L _{.DELTA..delta} current i _.delta.c as a proportional coefficient. Therefore, when the current i _.delta.c is negative, the value _(L δδ · _{i δc),} most increased when the value L _{.DELTA..delta} takes a minimum value. Note that the value L1 is negative (because Ld <Lq), as can be seen from equation (14) and FIG. 2, the value L _δδ is the minimum value when cos (2φc) takes 1 (= Ld ). Therefore, when the current i _δc is negative, the d-axis inductance Ld is adopted as the value L _δδ .

On the other hand, when the current i _.delta.c is positive, the value _(L δδ · _{i δc),} the value L _{.DELTA..delta} is largest when the maximum value. When it is noted that the value L1 is negative, as can be understood from the equation (14) and FIG. 2, the value L _δδ takes the maximum value (= Lq) when cos (2φc) takes -1. Therefore, when the current i _δc is positive, the q-axis inductance Lq is adopted as the value L _δδ .

In other words, among the d-axis inductance Ld and q-axis inductance Lq, whichever value _(L δδ · i δc) is increased, it may be adopted as the value L _{.DELTA..delta.} Thereby, the 3rd term of a formula (17) can be made the smallest.

Next, the value L _δγ is considered. Considering expand the left-hand side of equation (17), the value L _{[Delta] [gamma]} are included only in the equation the fourth term of the left side of _{(17) {-ω1 · L δγ} · i γc · sgn (ω1)}. When considering that holds, the fourth term, the value ω1 · sgn (ω1) = | | ω1 - represented by _{(| · L δγ · i γc} | ω1). Thus, when considered in fixing the value and the rotational speed ω1 of the other terms, the fourth term is most reduced when the value (L _{[Delta] [gamma]} · i _{[gamma] c)} is the largest, and thus the left-hand side of equation (17) is most Get smaller.

When it is noted that the value L1 is negative, as can be understood from the equation (14) and FIG. 2, the value L _δγ takes the maximum value (= −L1) when sin (2φc) takes 1, and sin When (2φc) takes 1, the maximum value (= −L0) is taken. Thus, the value (-L1) {= - (Ld -Lq) / 2}, L1 {= (Ld-Lq) / 2} of the person who values _(L δγ · i γc) increases, the value L _{[Delta] [gamma]} It may be adopted as. Thereby, the 4th term of a formula (17) can be made the smallest.

Since the value L _δγ varies along a sine wave (−L1 · sin (2φc)), the maximum value and the absolute value of the minimum value are equal to each other, and −L1 = (Lq−Ld) / 2. Thus the maximum value of the value _(L δγ · i γc) can be expressed (Lq-Ld) · max [ i γc, -i γc] also / 2.

  Based on the above contents, the step-out discrimination inequality can be expressed by the following formula.

Also by adopting the value L _{[Delta] [gamma]} as described above, regardless of the polarity of the current i _{[gamma] c,} the value _(L δγ · _i γc) value take {(Lq-Ld) · | / 2 | i γc}. Therefore, in the formula (19), max [i _γc , −i _γc ] may be represented by | i _γc |.

<3-3. Device constant>
Since the resistance value R, the d-axis inductance Ld, and the q-axis inductance Lq have variations in manufacturing or physical properties, <2-2. As described in “Device constant>, the variation may be taken into consideration.

  For example, when Expression (18) is used, a value that minimizes the left side of Expression (18) within a variation range may be employed as the resistance value R and the inductance Lq. More specifically, equation (11) may be used.

  Also when using equation (19), if the value with the smallest left side of equation (19) is adopted as the value of resistance value R, d-axis inductance Ld, and q-axis inductance Lq within the range of variation. Good.

  First, the resistance value R is considered. This resistance value R is included only in the second term on the left side of equation (19). Since this second term is the same as the second term of Equation (10), the resistance value R may be determined in the same manner as the second term of Equation (11).

Next, the third term on the left side of Equation (19) is considered. Out value of the third term (Ld · _{i δc),} as described above, a value current i _.delta.c is adopted as the maximum value of the value _(L δδ · _{i δc)} in the case of negative. Therefore, even when the variation of the d-axis inductance Ld is taken into consideration, it is necessary to determine the value of the d-axis inductance Ld so that the value (Ld · i _δc ) becomes the largest. Since the current i _δc is negative, the value (Ld · i _δc ) becomes the largest when the lower limit value Ld _min of the d-axis inductance Ld is adopted. Therefore, at this time, the lower limit Ld _min of the d-axis inductance Ld is adopted as the value L _δδ .

The value out of the third term (Lq · _{i δc),} as described above, a value current i _.delta.c is adopted as the maximum value of the value _(L δδ · _{i δc)} in the case is positive. Therefore, the value of the q-axis inductance Lq is determined so that the value (Lq · i _δc ) becomes the largest even when the variation of the q-axis inductance Lq is taken into consideration. Since the current i _δc is positive, the value (Lq · i _δc ) becomes the largest when the upper limit value Lq _max of the q-axis inductance Lq is adopted. Therefore, at this time, the upper limit value Lq _max of the q-axis inductance Lq is adopted as the value L _δδ .

In other words, among the upper limit value _{Ld max} and q-axis inductance Lq of the lower limit _{Ld min} of d-axis inductance Ld, whichever value _(L δδ · i δc) is increased, it may be adopted as the value L _{.DELTA..delta.}

Next, the fourth term on the left side of Equation (19) will be described. The fourth term is represented by {− | ω1 | · (Lq−Ld) · max [i _γc , −i _γc ] / 2} regardless of whether the current i _γc is positive or negative. Therefore, in consideration of variations in the d-axis inductance Ld and the q-axis inductance, the fourth term is the smallest when the value (Lq−Ld) is the largest. Therefore, the value (Lq _max −Ld _min ) is adopted as the value (Lq−Ld).

  When the above content is formulated, the following equation is derived.

  As a result, it is possible to avoid a situation in which step-out cannot be detected despite step-out due to variations in manufacturing or physical properties.

If the third and fourth terms on the left side of Equation (20) are described using the third and fourth terms on the left side of Equation (19), they can also be explained as follows. That is, in the third and fourth terms of the equation (19), the lower limit Ld _min is adopted as the d-axis inductance Ld and the upper limit Lq _max is adopted as the q-axis inductance Lq. These are the third and fourth terms.

  Further, in the above-described example, variation in both the resistance value R and the inductance is considered, but only one of them may be considered.

<4. Configuration of Electric Motor Drive Device>
With reference to FIG. 3, the electric motor drive system provided with the step-out detection device will be described. The electric motor drive system includes a drive device 1, an electric motor 2, a control unit 3, a determination unit 4, and a current detection unit 5. The drive device 1 applies an alternating voltage to the electric motor 2 and outputs an alternating current. Thereby, the electric motor 2 is driven. The electric motor 2 includes an armature 21 and a field 23. The armature 21 has an armature winding 22. In the illustration of FIG. 3, one end of each of the three armature windings 22 is connected to the driving device 1 and the other ends are connected to each other. Such a connection is called a so-called star connection. When a three-phase AC voltage is applied to these armature windings 22, the armature windings 22 apply a rotating magnetic field to the field magnets 23. The field magnet 23 supplies linkage flux (linkage flux to the armature 21 by the field magnet 23) to the armature 21, and rotates with respect to the armature 21 in synchronization with the rotating magnetic field.

  In the illustration of FIG. 3, the driving device 1 is an inverter, and inputs a DC voltage Vdc between the positive DC power supply line LH and the negative DC power supply line LL, and converts the DC voltage Vdc into an AC voltage. For example, the driving device 1 includes a pair of switching elements for three phases. A pair of switching elements of each phase are connected in series between the DC power supply lines LH and LL. A connection point connecting the pair of switching elements is connected to one end of the armature winding 22 corresponding to each phase. A diode may be connected in parallel to each switching element. The forward direction of the diode is a direction from the DC power supply line LL to the DC power supply line LH.

  The driving device 1 receives a control signal S from the control unit 3. Such a control signal is a signal for controlling application of an alternating voltage by the driving device 1. In other words, the driving device 1 is controlled by the control unit 3. For example, the control unit 3 gives a control signal (switching signal) S to the switching elements belonging to the driving device 1. The switching element is turned on / off based on the control signal S. By supplying an appropriate control signal S to the switching element, the driving device 1 can convert the DC voltage Vdc into an AC voltage and apply it to the electric motor 2.

  The drive device 1 and the electric motor 2 are not necessarily limited to three phases, and may be a single phase or three or more phases.

<5. Control>
<5-1. Specific example of command value for voltage applied to motor>
The voltage command (command about the voltage applied to the electric machine) [V _δ ^* , V _γ ^* ] for performing the control is, for example, the gap in the voltage equation (see equation (1)) in the δc-γc coordinate system of the motor. By _{setting the} magnetic flux [λ _δγc ] as [λ _δ ^* λ _γ ^* ] ^t and introducing the rotational speed command ω1 ^* for the rotational speed ω1, it can be easily obtained by the following equation. Here, as an example, the term of the differential operator is approximated to zero by assuming a steady state. However, this embodiment is not limited to this, and a differential operator may be considered.

In Expression (21), currents i _δc and i _γc are detected values. The currents i _δc and i _γc are detected by the current detector 5. The current detection unit 5 detects an alternating current flowing through the electric motor 2 (more specifically, the armature winding 22). In the illustration of FIG. 3, three-phase alternating currents iu, iv, and iw are detected, but only two-phase alternating currents may be detected. Ideally, the sum of the three-phase alternating currents iu, iv, and iw is zero, so that the remaining one-phase alternating current can be calculated from the two-phase alternating current. Then, the currents i _δc and i _γc are detected by calculating the currents i _δc and i _γc from the alternating current using a known coordinate transformation. The rotational speed ω1 is calculated as will be described later, for example. In the primary magnetic flux control, the air gap magnetic flux command λ _γ ^* is set to zero.

In equation (21), only so-called feedforward control is performed. Therefore, a deviation (hereinafter also referred to as an error) occurs between the voltage V _δc and the voltage command V _δ ^*, and an error can also occur between the voltage V _γc and the voltage command V _γ ^* . As a result, an error [Δλ] may also occur between the air gap magnetic flux [λ _δγc ] and the air gap magnetic flux command value [λ ^* ]. Further, with this error [Δλ], an error Δφ also occurs between the estimated phase angle φc and the load angle φ.

Therefore, feedback control may be performed to reduce such an error. For example, a value obtained by multiplying the deviation between the gap magnetic flux command value [λ ^* ] and the gap magnetic flux [λ _δγc ] by the feedback gain Gλ is added to the right side of the equation (21) as a feedback amount [B]. In the following, the right side of equation (21) is also defined as the feedforward amount [F]. The voltage command at this time is shown below.

  Although the feedback gain Gλ is shown as a scalar quantity, it may be a non-zero matrix of 2 rows and 2 columns that acts on the deviation of the air gap magnetic flux.

Ideally, when the feedback amount [B] becomes 0, the air gap magnetic flux [λ _δγc ] coincides with the air gap magnetic flux command value [λ ^* ], and the steady state represented by the equation (4) becomes _δc . This is realized by control in the -γc rotating coordinate system. As a result, the δ-γ rotational coordinate system coincides with the δc-γc rotational coordinate system.

Or you may obtain | require feedback amount [B] from the deviation of an electric current. Specifically, the feedback amount [B] may be obtained according to the equation (23). However, the feedback gain Gi (≠ 0) and the command value [i ^* ] = [i _δ ^* i _γ ^* ] ^t of the current [i _δγc ] were introduced. The feedback gain Gi may be a non-zero matrix of 2 rows and 2 columns that acts on the current deviation.

  Thereby, an error can be reduced. As a result, control can be performed with higher accuracy.

In feedback control, integral control or the like may be performed instead of or in combination with proportional control. Alternatively, the voltage command [V ^* ] may be calculated using only the feedback amount [B] without using the feedforward amount [F].

<5-2. Example of internal configuration of control unit>
The control unit 3 includes a rotation speed calculation unit 32, a phase calculation unit 33, coordinate conversion units 34 and 36, a voltage command calculation unit 35, and a control signal generation unit 37.

The rotation speed calculation unit 32 calculates the rotation speed ω1. For example, the rotation speed calculation unit 32 includes a speed command correction unit 321, a speed compensation unit 322, and a subtracter 323. The speed command correction unit 321 inputs, for example, a rotational speed command (machine) ωrm ^* for the electric motor 2 from the outside, and multiplies this by the number of pole pairs of the motor to generate a rotational speed command (electrical) ω1 ^* . The speed compensation unit 322 receives, for example, the current i _γc , removes the direct current component of the current i _γc , multiplies it by a constant, and outputs it as a compensation amount to the subtracter 323. The subtracter 323 calculates the rotational speed ω1 by subtracting the compensation amount from the rotational speed command ω1 ^* . Such calculation of the rotational speed ω1 is as described in Non-Patent Document 2. Note that the rotational speed ω1 may be calculated as described in Non-Patent Document 1.

  The phase calculator 33 receives the rotational speed ω1 and integrates it to calculate the phase angle θ. This phase angle θ corresponds to the phase angle between the fixed coordinate system (fixed coordinate system of the UVW phase) and the δc-γc rotating coordinate system.

The coordinate conversion unit 34 receives the alternating currents iu, iv, iw from the current detection unit 5 and the phase angle θ from the phase calculation unit 33, and calculates the currents i _δc , i _γc using well-known coordinate conversion.

The voltage command calculation unit 35 receives the rotational speed ω1, the currents i _δc and i _γc and the air gap magnetic flux command value [λ ^* ], and calculates the voltage commands V _δ ^* and V _γ ^* as described above. When device constants (resistance value R, inductances Ld, Lq, and flux linkage Λ0) are required, these are stored in the control unit 3 in advance.

The coordinate conversion unit 36 receives the voltage commands V _δ ^* and V _γ ^* and the phase angle θ, and uses a known coordinate conversion in the three-phase fixed coordinate system for the AC voltage output from the driving device 1. Voltage commands Vu ^* , Vv ^* , Vw ^* are calculated.

The control signal generator 37 receives the voltage commands Vu ^* , Vv ^* , Vw ^* , and generates a control signal (switch signal of the switching element belonging to the inverter) for controlling the driving device 1 in a known manner. For example, the control signal is generated based on a comparison between the carrier and the voltage commands Vu ^* , Vv ^* , Vw ^* .

<5-3. Judgment part>
The determination unit 4 inputs currents i _δc and i _γc from the coordinate conversion unit 34, inputs voltage commands V _δ ^* and V _γ ^* from the voltage command calculation unit 35, and inputs a rotation speed ω 1 from the rotation speed calculation unit 32. To do. In the control unit 3 (or determination unit 4), device constants (or further upper limit values and lower limit values thereof) are appropriately stored.

The determination unit 4 appropriately uses the currents i _δc , i _γc , the voltage commands V _δ ^* , V _γ ^*, and the rotation speed ω 1 to appropriately determine the step-out determination inequality (for example, the expressions (9) to (12) and (17) ) To any one of the expressions (20)). At this time, the voltage V _γc , the rotation speed ω 1, the current i _δc , i _γc of the step-out determination inequality equation, respectively, the voltage command V _γ ^* , the rotation speed ω 1 calculated by the rotation speed calculation unit 32, and the current detection unit 5 and the current i _δc , i _γc detected by a pair of the coordinate converter 34 are used.

  When the determination unit 4 determines that the step-out determination inequality is not satisfied, for example, the step-out signal J is output to detect step-out. As a result, the inverse trigonometric function is not necessary, and the step-out can be detected with a simpler calculation. The step-out signal J may be input to the control signal generator 37, for example. For example, when the occurrence of the step-out is recognized based on the step-out signal J, the control signal generation unit 37 outputs a control signal S for stopping the drive unit 1 to the drive unit 1. Thereby, it can avoid operating the electric motor 2 in a step-out state.

Note that the voltage command calculation unit 35 and the pair of the current detection unit 5 and the coordinate conversion unit 34 are a voltage acquisition unit that acquires the voltage command V _δc ^*, and a current acquisition that acquires the currents i _δc and i _γc , respectively. You can grasp the department. However, as the voltage V _δc , not only the voltage command V _δc ^* but also a detection value (or estimation value) may be adopted by providing a detection unit (or estimation unit). On the other hand, as the currents i _δc and i _γc , a command generation unit (or estimation unit) may be provided and command values (or estimation values) may be adopted.

In the above example, the case where primary magnetic flux control is mainly performed has been described as an example. However, the control may be performed by setting the δc-γc rotating coordinate system as follows. For example, the δ-γ rotating coordinate system is set in phase with a physical vector (such as voltage or current) expressed as a variable in the voltage equation. And you may perform control which makes (delta) c-gamma rotational coordinate system correspond with (delta) -gamma rotational coordinate system. This control is performed, for example, by setting a command (eg, voltage command V _γ ^* ) for a γ-axis component (eg, voltage V) of a physical vector (eg, voltage [V _δγc ]) to zero. Even in this case, the range of the estimated phase angle φc at which the motor does not step out is appropriately set, and the technical idea similar to that described above is used by using the voltage equation in the δ-γ rotating coordinate system and the range. Is used to derive a step-out discrimination inequality that does not use the estimated phase angle φc.

  In the range where the rotational speed ω1 is large, the term including the resistance value R of the step-out discriminant is smaller than the term including the rotational speed ω1, and therefore the term including the resistance value R may be approximated to zero. . Thereby, the step-out discriminant can be simplified. That is, when it is determined whether or not the rotational speed ω1 is greater than the predetermined reference value, and the determination is positive, the resistance value R may be approximated to zero.

  The various embodiments described above can be appropriately combined as long as the functions of each other are not impaired.

  The above block diagram is schematic, and each unit may be configured by hardware, or may be configured by a microcomputer (including a storage device) whose function is realized by software. Various procedures executed by each unit or various means or various functions implemented may be realized by hardware.

  The microcomputer executes each processing step (in other words, a procedure) described in the program. The storage device is composed of one or more of various storage devices such as a ROM (Read Only Memory), a RAM (Random Access Memory), a rewritable nonvolatile memory (EPROM (Erasable Programmable ROM), etc.), and a hard disk device, for example. Is possible. The storage device stores various information, data, and the like, stores a program executed by the microcomputer, and provides a work area for executing the program. It can be understood that the microcomputer functions as various means corresponding to each processing step described in the program, or can realize that various functions corresponding to each processing step are realized.

_{DESCRIPTION OF SYMBOLS} 1 Drive apparatus 2 Electric motor 4 Judgment part 5 Current detection part 21 Armature 22 Armature winding 23 Field 32 Rotational speed calculation part 34 Coordinate conversion part 35 Voltage command calculating part V ( _delta ⁾ _c ^* , V ( _gamma ⁾ _c ^* Voltage instruction i ( _{delta) c} , i _γc current ω1 ^* Rotation speed command

Claims (6)

In an electric motor drive device having an electric motor (2) having a field (23) and an armature (21) including an armature winding (22), and a drive device (1) for outputting a voltage to the electric motor. , A device for detecting step-out of the electric motor,
In a rotating coordinate system having a δc axis that forms a phase angle (φc) with respect to the d axis in phase with the interlinkage magnetic flux by the field, and a γc axis whose phase advances 90 degrees in the first direction with respect to the δc axis, A current acquisition unit (5, 34) for acquiring a current ([i _δγc ]) flowing through the armature winding;
A rotation speed calculation unit (32) for calculating a rotation speed (ω1) of a rotation coordinate having the δc axis and the γc axis;
An AC voltage acquisition unit (35) for acquiring an applied voltage ([V ^* ]) that is a voltage applied to the armature winding or an instruction thereof in the rotational coordinate;
In the voltage equation of the electric motor at the rotational coordinates, the electric motor is derived using the range of the phase angle when the electric motor rotates without being out of step, does not include the phase angle, the current, the rotational speed, and the A step-out detection comprising: a step-out detection inequality that determines whether or not a step-out determination inequality including a voltage as a variable is satisfied, and that determines that the motor has stepped out when the step-out determination inequality is not satisfied. apparatus. The range of the phase angle (φc) is a range of −x (x is 0 degree or more and less than 180 degrees) degree or more and x degree or less,
Among the voltage equation, the voltage _{([V δγc])} to the voltage equation for component (V _{[gamma] c)} of the [gamma] c-axis, the cosine value of the phase angle (cosφc) is included as a term,
The determination unit (4) is derived by transforming the voltage equation for the γc-axis component of the voltage to indicate the cosine value, the current ([i _δγc ]), the rotation speed (ω1), The step-out detection according to claim 1, wherein the step-out detection is detected when an equivalent expression including the γc-axis component of the voltage as a variable is smaller than a reference value determined in accordance with the range of the phase angle. apparatus. The upper limit value and the lower limit value of the range of the phase angle (φc) are −90 degrees and 90 degrees, respectively.
The resistance value and inductance of the armature winding, the rotation speed, the γc-axis component of the acquired voltage, the γc-axis component and the δc-axis component of the current are R, Lq, ω1, and V _γc , respectively. , I _γc and i _δc , the rotation speed is positive when the rotation direction of the motor is the first direction, and the rotation speed is negative when the rotation direction is opposite to the first direction. Assuming
The determination unit (4), when the positive and negative polarities of formula _{V γc -R · i γc -ω1 ·} Lq · it δc is different from the positive and negative polarities of the rotational speed, to detect the out-of claim 2 The step-out detection device described in 1. The determination unit (4)
When the rotation direction is the first direction, the resistance value is a value R out of an upper limit value and a lower limit value of a range in which the resistance value varies within a guaranteed range of manufacturing tolerance and operating temperature of the motor. Adopting the one in which i _γc becomes larger, and adopting the one in which the value R · i _γc becomes smaller when the rotational direction is opposite to the first direction,
4. The value of Lq · i _{δc that} is larger _among the upper limit value and the lower limit value of the range in which the inductance varies within the guaranteed range of the manufacturing tolerance and operating temperature of the motor is adopted as the inductance value. Step-out detection device. The field (23) is a field having a reverse saliency,
The upper and lower limits of the range in which the resistance value of the armature winding fluctuates within the guaranteed range of manufacturing tolerance and operating temperature of the motor, the d-axis component of the inductance of the armature winding, and the d-axis The q-axis component that advances by 90 degrees in the first direction is the upper and lower limits of the range that fluctuates within the guaranteed manufacturing tolerance and operating temperature of the motor, the rotational speed, and the γc-axis component of the voltage. each components and components of the .delta.c axis of the [gamma] c-axis of the _{current, R min, R max, Ld} min, Ld max, Lq min, Lq max, ω1, V γc, and i _{[gamma] c} and i _.delta.c, the electric motor The rotational speed is positive when the rotational direction is the first direction, the rotational speed is negative when the rotational direction is opposite to the first direction, and s when x> 0. n (x) = 1, x <0 sgn when (x) = - 1 and then, a> when _{b max [a, b] =} a, a < time b max [a, b] = When b ,
The determination unit (4) has the formula _{V γc · sgn (ω1) -max} [R min · i γc · sgn (ω1), R max · i γc · sgn (ω1)] - | ω1 | · max [Ld min _{· i δc, Lq max · i} δc] - | ω1 | when _{· (Lq min -Ld max) /} 2 · max [i γc, -i γc] is negative, detects the step-out, claim The step-out detection apparatus according to 2. A step-out detection device according to any one of claims 1 to 5,
The electric motor;
An electric motor drive system comprising the drive device.

Images