JPH1118468A - Controller for reluctance type synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure an efficient and stabilized motor control by providing a section for operating coefficients from a functional pattern variable with reference to the rotor speed and multiplying the coefficient by an operational angle to determine an operational angle variable with the rotor speed. SOLUTION: An armature current command value STC is delivered to a characteristics correcting section 4 and an operational angle operating section 3. It is then passed via a current command operating section 5, to produce a current command value SAC which is subjected to phase distribution before driving a motor 9 through an amplifier 8. The operational angle operating section 3 receives the armature current command value STC and a rotor speed SPD and delivers a corrected operational angle SAC to a current phase control section 7. According to the arrangement, the operating point can be controlled efficiently by operating respective functional patterns at the operational angle operating section 3, and the motor characteristics correcting section 4 using the rotor speed SPD and the current command value SIC as parameters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a synchronous motor used in machine tools, industrial machines, electric vehicles and the like, and more particularly to an improvement in control characteristics of a reluctance type synchronous motor.

[0002]

2. Description of the Related Art FIG. 11 shows a conventional example. Three phases (U, V,
The control in (W phase) will be taken as an example. The speed command value SVC is instructed by the host controller, and the subtractor 1 calculates the difference DIF between the rotor speeds SPD. PI controller 2 with DIF input
As a result, the armature current command value STC is output to the current command calculation unit 5. Further, a field current command value SFC is output to the current command calculation unit 5 based on the field current pattern in the field current calculation unit 101 with reference to the rotor speed SPD. The current command calculation unit 5 refers to the rotor position SP (mechanical angle), converts it into an electrical angle, and then converts the armature current command value STC and the field current command value SF
C is vector-operated and the current command value SIC (SIUC, SUC
IVC). (Note that the phase difference between the armature current command value STC and the field current command value SFC is π / 2 [rad] in electrical angle.) Then, the U-phase current command value SIUC and the phase difference (2π) / 3 thereof Alternatively, the V-phase current command value SIVC of (4π) / 3 [rad] is distributed in phases. If two of the three phases are determined, the current (SIWC) of the remaining W phase is determined, so that it is not shown. The current command value of each phase is applied as a three-phase current to the motor 9 via the amplifier 8 to rotate the rotor of the motor 9. The rotor position SP is obtained by a detector 10 as rotor position detecting means attached to the rotor, and is fed back to the current command calculator 5 and the differentiator 12. The differentiator 12 differentiates the rotor position SP and outputs the result to the subtractor 1 and the field current calculator 101 as the rotor speed SPD. As can be seen from the above operation, the current command value S
The IC is made by vector-adding the field current command value SFC and the electronic current command value STC (see FIG. 2). When controlling,
If the angle formed between the armature current command value STC and the current command value SIC is called an operation angle α21, the armature current command value S
When the TC and the field current command value SFC change, the operating angle α also changes. Also, when performing the field weakening control, if the armature current command value STC> the field current command value SFC, the operating angle approaches α 近 0. When the current is not in the field weakening region, the field current command value SFC takes a constant value. The motor characteristics in this case are as follows: when the armature current: Iq is set on the x-axis and the output torque: τ is set on the y-axis, the field current: Id
It has been experimentally confirmed that the output torque characteristics have linear characteristics as shown in FIG. 6A, which will be described later in detail, when (1 ×, 2 ×, 3 ×, 4 ×) is a parameter. However, when the field current is low (the characteristic curve 65 in FIG. 6B, the area A) or large (FIG. 6B, the characteristic curve 65 in the area C), the non-linear characteristic portion as shown in FIG. Occur.
The characteristics of FIG. 6 will be described later in detail.

[0003]

When the conventional control device is used, the current command value SIC becomes the field current command value SF.
C and the armature current command value STC are created by vector addition. Therefore, when the armature current command value STC and the field current command value SFC change, the operation angle α becomes indefinite. This means that the efficiency and the power factor of the torque obtained with respect to the current always change, and a control defect (for example,
When an attempt is made to obtain torque when the field current is low, the armature current increases, so that the combined current (current command) also increases. However, the efficiency is poor because the torque output is small for a large current. In addition, due to the influence of leakage inductance from the q-axis (dq-axis theory of vector control) through which the armature current flows to the d-axis, the flux of the d-axis component increases despite the field weakening. → Increase in induced voltage → Saturation of power supply voltage → Decrease in applied current → Inability to control, a diagram of the problem is established. ) Occurs. Also, as described above, when the armature current command value STC> the field current command value SFC (when the operation angle α ≒ 0), the torque constant decreases and the control target does not operate, so the torque command value increases. However, there is a possibility that a hunting phenomenon or in the worst case, loss of control may occur due to a control delay. The above is also observed in a non-linear motor output characteristic region when the combined current is low. The present invention has been made under the circumstances described above,
It is an object of the present invention to provide a control device for a reluctance type synchronous motor capable of stably and efficiently controlling an electric motor with a simple configuration.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to supply a constant direct current to a winding provided in a stator slot,
Torque generated with respect to rotation angle θ when rotating a rotor with magnetic insulation inside so that the magnetic resistance of the rotor surface made of soft magnetic material has a height difference in the direction of rotation when viewed from the stator τ is a reluctance type synchronous motor control device having a positive and negative periodic characteristics, a means for detecting the rotor position of the rotor, and the rotor position for flowing a current to the motor, In a control device including a current command calculation unit for calculating a current command from a torque command value, a sign is determined based on the polarity of the torque command value, and an operation angle α (0 <α <π / 2 [ rad]; electrical angle)
And a function pattern A that changes with reference to the rotor speed
The current angle control unit has an operation angle calculation unit that calculates the coefficient A and multiplies the operation angle to change the operation angle according to the rotor speed, and multiplies the current command value in the current amplitude control unit to obtain the corrected current command value. The motor drive efficiency or the output torque characteristic is provided by a mode selector that has a damping value calculation unit that calculates a simple coefficient B from a function pattern B that changes with reference to the rotor speed. Has a damping value calculation unit that can select a mode in which control can be performed so as to give priority to the input, and converts the command value output to the input command value so that it has linear motor characteristics, and the nonlinear characteristics of the motor This is achieved by having a motor characteristic / command conversion unit that treats as a linear. In the present invention, the operating angle α (0 <α <π / 2 [ra], whose sign is determined by the polarity of the torque command value and is added to the rotor position.
d]; electrical angle), and has an operation angle calculation unit that calculates the coefficient A from a function pattern A that changes with reference to the rotor speed and multiplies the operation angle to change the operation angle according to the rotor speed. As a result, an efficient control device was obtained. In addition, a mode selector that can be set from outside the controller allows
A mode in which control can be performed so as to give priority to motor drive efficiency or output torque characteristics can be selected, and a coefficient B that makes the corrected current command value by multiplying the current command value in the current amplitude control unit is referred to the rotor speed. Thus, a control device with good controllability was obtained by having an attenuation value calculation unit that calculates from the function pattern B that changes. In addition, since a reluctance motor having nonlinear characteristics can be controlled like a motor having linearity like a permanent magnet synchronous motor, there is an advantage that the motor can be used for servo applications such as machine tools.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Unless otherwise specified, components having the same symbols and numbers have the same configuration and function. FIG. 1 is an example of a control block diagram of the present invention. A portion that instructs the speed command value SVC from the host controller, calculates the difference DIF from the rotor speed SPD by the subtractor 1, and outputs the armature current command value STC to the current command calculation unit 5 by the PI controller 2 This is the same as the conventional example. The armature current command value STC is output to the characteristic correction unit 4 and the operating angle calculation unit 3. The characteristic correction unit 4 calculates the corrected armature current command value STCC, and outputs the current command value SIC via the current command calculation unit 5. (S
IUC, SIVC), and after the phase distribution, the motor 8 is driven by the amplifier 8. A detector 10 for detecting the rotor position of the electric motor 9 is attached, and outputs the rotor position SP to the current phase controller 7 and the differentiator 12 of the current command calculator 5. Further, the rotor position SP becomes the rotor speed SPD by the differentiator 12, and the operation angle calculation unit 3 which is a feature of the present invention is provided.
Is output to the attenuation value calculator 11. The armature current command value STC and the rotor speed SPD are input to the operating angle calculation unit 3, and the corrected operating angle SAC is output to the current phase control unit 7. The current command calculation unit 5 includes a current amplitude control unit 6 and a current phase control unit 7 having a phase distributor. The current amplitude control unit 6 includes a coefficient SK2 output from the attenuation value calculation unit 11 and a correction electric machine. The child current command value STCC is calculated and the current command value SI
C. The current phase controller 7 receives the current command value SIC from the current amplitude controller 6, the corrected operating angle SAC from the operating angle calculator 3, and the rotor position SP from the detector 10. You. Here, the current phase controller 7
To be more specific, the mechanical angle (2πrad for one rotation of the rotor) becomes an electrical angle (2πrad for one cycle of a sine wave) so that the rotor position SP can be used for control.
It becomes 2πrad for one magnetic pole pair of the rotor. ), The phases are adjusted so that a current flows on the q axis (armature current) of the rotor magnetic pole. Then, the phase is shifted by the adder by the corrected operating angle SAC, and after the U-phase and V-phase operations (3
In the case of a phase, when two phases are determined, one phase (W phase) is automatically determined. ), The current command value SIC and the shifted phase are calculated for each phase by a multiplier, and output as a U-phase current command value SIUC and a V-phase current command value SIVC. Attenuation value calculator 1
1 is a coefficient S by referring to the rotor speed SPD for each of the drive efficiency priority mode and the constant output control mode selected by the signal MODE from the external operation mode selector.
K2 is output to the current amplitude controller 6. The operating angle calculating unit 3 also internally refers to the rotor speed SPD, internally calculates a coefficient Ka, and multiplies the operating angle α to obtain the corrected operating angle Ka · α.
(= Α ′) is output to the current phase controller 7.

FIG. 2 shows a current vector diagram. The angle between the armature current Id and the combined current Io is defined as an operation angle α. When the vectors in the figure are represented by relational expressions, they are as shown in [Equation 1] and [Equation 2].

[Equation 1] Field current component: Id = Io · sinα

## EQU2 ## Armature current component: Iq = Io · cos α That is, the applied current (synthetic current) Io can be divided into a field current component Id and an armature current component Iq as in conventional vector control.

FIG. 3 shows a characteristic example of a motor to which the present invention is applied. In a three-phase (U, V, W phase) motor, V, W
This is a characteristic showing the generated torque τ with respect to the rotation angle θ when a phase terminal is short-circuited and a direct current flows in the U → V, W phase. The characteristic curve 36 is the rated current Io, the characteristic curve 35 is twice the rated current Io, the characteristic curve 34 is three times the rated current Io,
The characteristic curve 33 is a torque characteristic when the rated current Io is four times the rated current, and the characteristic curve 32 is a torque characteristic when the rated current Io is five times. As described above, it can be seen that the magnitude of the torque τ generated by the difference in the magnitude of the DC current and the angle θ indicating the peak torque (P1 to P5) are different. In this figure, when the DC current is fixed to Io, when the angle θ = 0, [Equation 1]
According to [Equation 2], the field current component is 0% and the armature current component is 100% with respect to Io. When the angle θ = π / 2 (electrical angle), the armature current is 100% and the field current component is 100%. Is 0%. When the angle θ = π / 4 (electrical angle), it can be regarded as the generated torque τ when about 71% of both the field current component and the armature current component flow to Io. Angle θ =
In the case of the operating angle α, since the value of the flowing current is known, the torque value obtained from the characteristic curve can be known, and by using the above [Equation 1] and [Equation 2], the field as in the conventional vector control is obtained. It is possible to apply a concept in which the magnetic current component and the armature current component are separated.

FIG. 4 shows an example of a control block diagram in the operation angle calculation unit 3. FIG. 5 shows a function pattern of the counting operation 41. The operating angle calculating unit 3 calculates a coefficient calculating unit 41 that outputs a coefficient Ka with reference to the rotor speed SPD and an operating angle α of an initial fixed value by a multiplier 42, and calculates a corrected operating angle Ka · α.
Is output. At this time, the polarity of the torque command value STC is determined by the polarity determining unit 46, the sign switch 43 of the corrected operating angle Ka · α is determined, and the coefficient 44,
Alternatively, the corrected operating angle SAC is output by multiplying by the coefficient 45. The arithmetic unit 41 has an arithmetic expression or a data table using the rotor speed SPD as a parameter.
As shown in FIG. 5, the function changes with the base rotation speed Nbase, and the coefficient Ka is calculated.

FIG. 6A is a graph showing the torque τ with respect to the armature current Iq, and is a characteristic diagram in which the field current Id flows 1, 2, 3, and 4 times. However, the torque characteristics do not increase proportionally. In other words, FIG. 6B shows the characteristics of the field current Id and the armature current Iq with respect to the combined current Io. This is the combined current Io
Torque that can be generated with respect to (operation angle α = undefined))
Is shown. As can be seen from the characteristic curve 65, the area A
, The output torque increases quadratically with respect to the current, and the current torque increases linearly in the region B. The characteristics of the region C vary according to a quadratic function, though depending on the design of the motor. (The area C is often not actively used in a normal motor design.) The reason for the characteristic of the area A is that the field current component of the applied current is consumed in the air gap between the rotor and the stator. It is considered that the field magnetic flux in the rotor is insufficient. The linear characteristic portion in the region B is a characteristic in a case where energy consumption in the air gap is saturated and a sufficient field magnetic flux is formed in the rotor. In the region C, this is a characteristic that occurs because the field magnetic flux is saturated in the air gap portion and the rotor.

FIG. 7 shows an example of a pattern of the characteristic correction section 4.
A pre-correction torque command value STC is obtained as an input, and a post-correction torque command value STCC is obtained as an output. The correction curve 71 is
In order to correct the torque characteristics of the electric motor (see FIG. 6B), each of the regions A, B, and C has a complementary function shape.
By using 1, an approximately linear motor characteristic such as a straight line 72 can be obtained. The characteristic correction unit 4 can also cancel by matching the function pattern to the motor characteristics.

FIG. 8 shows an example of the attenuation value calculator 11 and an example of a function pattern using the rotor speed SPD as a parameter. The attenuation value calculator 11 has a switch 83 set by the rotor speed SPD and a signal MODE from an external mode selector.
The motor control method can be selected between the motor efficiency priority mode and the constant output priority mode by the external mode selector. The control method is not limited to the one described above, and the operation unit 81,
By manipulating the function pattern as shown at 82, control for each purpose can be realized. (For example, if the torque is to be increased only when the rotational speed is low, it is possible to set the coefficient of the low rotational speed portion to 1.0 or more.
Amplification is also possible depending on the setting of the function pattern. The coefficient SK2 is output to the current amplitude control unit 6 according to a function pattern using the rotor speed SPD selected by the switch 83 as a parameter.

FIG. 9 specifically shows the difference in operating point in the motor characteristic diagram as shown in FIG. 3 by the mode selector. In both cases, the operating point (operating angle α and output torque τ) when the control mode is switched by the selector when the field current components are the same.
Show the difference. The operating point in the constant output mode is Q, and the efficiency priority mode is P. Since the operation angle α is different even for the same field current, the magnitude of the current command value (combined current Io) is different. At the operating point Q, the output torque is large, but is shifted from the peak of the characteristic curve 92 from the viewpoint of efficiency, so that the torque (= energy conversion rate) obtained with respect to the absolute value of the current is low. The efficiency is lower than the operating point P controlled by the peak of the curve 91. (Because the operating point P is at the peak of the characteristic curve 91, the efficiency of the torque obtained with respect to the current is good.) In other words, when the field current is the same, the absolute value of the obtained torque is large because the combined current Can be said to be the operating point P where the efficiency is high. Selecting the control mode is synonymous with selecting the operating point α. By operating each function pattern of the operating angle calculator, the attenuation value calculator, and the motor characteristic correction unit, this operating point α is selected.
Can be controlled using the rotor speed SPD and the current command value SIC as parameters.

[0013]

As described above, according to the control apparatus for a synchronous motor shown in the present invention, the operating angle calculating section for calculating the coefficient that changes with reference to the rotor speed and the damping value calculating section capable of setting the control mode. Therefore, control (including field weakening control) equivalent to performing vector control can be performed. Further, since the field current component is included in the combined current, the field current at the time of small torque can be reduced, and power saving, small heat generation of the windings, and highly efficient control can be realized. When a large torque is required during acceleration or deceleration, the combined current increases and the field current component also increases, so that the torque constant can be increased and the acceleration time can be reduced. Further, since a motor characteristic correction unit for outputting a correction torque characteristic in response to an input torque command is provided, it is possible to control a motor having a non-linear torque characteristic like a motor having good linearity characteristics. The present invention is not limited to the embodiment of the present invention shown in FIGS. 1 to 10 described above, and the following modifications may be made without departing from the gist of the present invention. (1) In this embodiment, a three-phase motor has been described, but a multi-phase motor having two or more phases may be used. (2) In the present embodiment, the motor having the rotor has been described, but the present invention may be applied to a linear motor having a structure having a mover. (3) In the present embodiment, the method of controlling the combined current Io and the operating angle α has been described. However, FIG. 10 shows an example in which the present invention is applied to a vector operation equivalent to that of the present invention (controlled independently of d-axis and q-axis currents). Is shown. An example of an arithmetic expression and a function pattern in that case is shown below. When controlling the operating point α, the field current Id,
The calculation when the armature current Iq is independently vector-calculated is as shown in [Equation 3].

## EQU3 ## Io = KIq.Iq + KId1.Kid2.Id FIG. 10A is an example of a function pattern of a coefficient KId1 (field weakening coefficient) multiplied by a field current Id with the motor speed N as a parameter. FIG. 10B is an example of a function pattern of a coefficient KIq (torque damping coefficient) by which the armature current Iq is multiplied by the motor rotation speed N as a parameter. FIG. 10 (c)
Is the field current I with the torque command value STC as a parameter.
It is an example of a function pattern of a coefficient KId2 (torque reduction coefficient) by which d is multiplied. By making this coefficient constant irrespective of the rotation speed (for example, KId2 = 1.0), the field current constant value (however, a function of the rotation speed N) regardless of the torque command value.
It is also possible to control with.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a control device for a synchronous motor of the present invention.

FIG. 2 is a current vector diagram used in the control device for a synchronous motor of the present invention.

FIG. 3 is a characteristic example of a motor used in a control device for a synchronous motor of the present invention.

FIG. 4 is an example of a block diagram of an operation angle calculation unit included in the control device for the synchronous motor of the present invention.

FIG. 5 is an example of a function pattern of an operation angle calculation unit provided in the control device for a synchronous motor of the present invention.

FIG. 6 is a characteristic example of a motor used in a control device for a synchronous motor of the present invention.

FIG. 7 is an explanatory diagram of a motor characteristic correction unit provided in the synchronous motor control device of the present invention.

FIG. 8 is an operation example of a mode selector of the attenuation value calculation unit provided in the synchronous motor control device of the present invention.

FIG. 9 is an explanatory diagram of an operation point by a mode selector of an attenuation value calculation unit provided in the control device for a synchronous motor of the present invention.

FIG. 10 is an application example of a modified embodiment of the synchronous motor control device of the present invention.

FIG. 11 is a block diagram of a conventional control device for a synchronous motor.

[Explanation of symbols]

1 subtracter, 2 PI controller, 3 operating angle calculator, 4
Characteristic correction unit, 5 current command calculation unit, 6 current amplitude control unit, 7 current phase control unit, 8 amplifier, 9 motor, 1
0 detector, 11 attenuation value calculator, 12 differentiator, 21
Operating angle: α, 22 Field current component: SFC (Id),
Reference Signs List 23 armature current component: STC (Iq), 24 combined current: SIC (Io), 31 to 36 torque characteristics (rotation angle-torque), 41 coefficient calculation unit, 42 multiplier, 43
Switch, 44, 45 coefficient multiplier, 46 polarity judging section, 51 coefficient Ka function pattern, 61 to 64 torque characteristics (armature current-torque (field current)), 65 torque characteristics (synthetic current-torque), 71 characteristics Correction curve, 7
2 Characteristic curve after correction, 81, 82 Coefficient operation unit, 83 mode switch, 91 Torque characteristic (current: Io), 92
Torque characteristics (current: Io / 2), 101 field current calculation unit, 111 to 113 coefficient calculation unit function pattern.

Claims (4)

[Claims] A constant DC current is applied to a winding provided in a stator slot, and a magnetic resistance is formed inside the rotor such that a magnetic resistance on a surface of a rotor made of a soft magnetic material has a height difference in a rotational direction when viewed from the stator. A control device for a reluctance motor in which a torque τ generated with respect to a rotation angle θ when a rotor having insulating means is rotated has positive and negative periodic characteristics, wherein a rotor of the rotor is provided. A control device comprising: means for detecting a position; and a current command calculation unit for calculating a current command from the rotor position and a torque command value in order to cause a current to flow through the motor, wherein a sign is determined by the polarity of the torque command value. Has an operating angle α (0 <α <π / 2 [rad]; electrical angle) that is added to the rotor position, and calculates a coefficient A from a function pattern A that changes with reference to the rotor speed. Operating angle by rotor speed A reluctance type synchronous motor control device, characterized in that it has an operation angle calculation unit that changes. 2. A damping value calculation for calculating a coefficient B for obtaining a corrected current command value by multiplying the current command value in a current amplitude control section from a function pattern B changing with reference to the rotor speed. A control device for a reluctance type synchronous motor, characterized by having a section. 3. A mode in which control can be performed so as to give priority to motor drive efficiency or output torque characteristics by a mode selector that can be set from outside the controller.
A control device for a reluctance type synchronous motor, characterized by having a damping value calculation unit according to (1). 4. A motor characteristic / command conversion unit for converting an input command value into an output command value so as to have a linear motor characteristic and treating a non-linear characteristic of the motor in a linear manner. A control device for a reluctance type synchronous motor, comprising: