HK1161441A - Control device for permanent magnet synchronization electric motor - Google Patents

Abstract

A control device for a permanent magnet synchronization electric motor can be obtained, capable of performing a high-accuracy torque control without increasing load on a CPU product, regardless of whether the permanent magnet synchronization electric motor is an SPM motor or an IPM motor, not only during a low-speed operation or a medium-speed operation but also during a high-speed operation. The control device comprises a torque correction circuit (1, 2, 3a) that generates, from the current phase (βi) of each of current modification commands (id*cmd, iq*cmd) for a d-axis and a q-axis and a torque command (Tm*), a torque modification command (Tm*cmd) and supplies the torque modification command (Tm*cmd) to a d/q-axis current command generator (9) in place of the torque command (Tm*).

Description

Control device for permanent magnet synchronous motor

Technical Field

The present invention relates to a control device for a permanent magnet synchronous motor.

Background

In the control of a permanent magnet synchronous motor, a vector control capable of freely controlling a torque is often used. A control device using vector control is configured to control a PWM inverter by a current controller that performs proportional-integral control by decomposing 3-phase motor current output from the PWM inverter to a permanent magnet synchronous motor on d-and q-axis coordinates that are 2 axes that rotate and are orthogonal to each other, and converting the current into a d-axis current that is an excitation current component and a q-axis current that is a torque assist component so that the converted d-axis current and q-axis current that actually flow in the permanent magnet synchronous motor follow a d-axis current command and a q-axis current command generated based on a torque command transmitted from the outside.

Accordingly, the accuracy of torque control performed by the control device for the permanent magnet synchronous motor depends on whether or not appropriate d-axis and q-axis current commands can be generated by a d/q-axis current command generator that generates a d-axis and q-axis current commands based on a torque command transmitted from the outside.

Here, in the Permanent magnet synchronous motor, a torque generation formula of the spm (surface Permanent magnet) motor having no saliency (saliency) is given by equation (1). In addition, in the formula (1), T_m ^*Is a torque command sent from the outside, i_q ^*Is q-axis currentInstruction, K_tIs the torque constant of a permanent magnet synchronous motor.

[ equation 1]

T_m ^*＝K_ti_q ^* …(1)

If the equation (1) is modified to the equation (2) below and the d/q-axis current command generator is configured to perform the calculation based on the equation (2), the torque can be controlled. In addition, in equation (2), i_d ^*Is the d-axis current command.

[ equation 2]

In addition, in the Permanent magnet synchronous motor, a torque generation formula of an ipm (interior Permanent magnet) motor having a saliency is given by the following equation (3). In addition, in equation (3), P_m、L_d、L_qThe number of pole pairs (numbers of pole pairs), d-axis inductance, and q-axis inductance of the permanent magnet synchronous motor are provided.

[ equation 3]

T_m ^*＝K_ti_q ^*+P_m(L_d-L_q)i_d ^*i_q ^* …(3)

In the IPM motor, if the d/q-axis current command generator is configured to perform the calculation based on the equation (3), or configured to refer to table data prepared in advance based on the equation (3), the torque can be controlled. Further, since it is generally known that the d-axis inductance and the q-axis inductance vary non-linearly with the magnitude of the current, if the d/q-axis current command generator is configured taking this into consideration, the accuracy of the torque control can be improved.

However, in recent years, in order to operate a permanent magnet synchronous motor at a high speed, there is an increasing demand for operation in a constant output region where the inverter output voltage is used up. In this operation, it is necessary to suppress saturation of the inverter output voltage, and therefore, as one of the methods, so-called field weakening control in which a d-axis current is increased in a negative direction is often performed.

One method of field weakening control is shown in patent document 1 (fig. 11). If the method is applied to a control device of a permanent magnet synchronous motor, it is as follows. That is, the q-axis voltage saturation amount is obtained from the deviation between the q-axis voltage component and the q-axis voltage command, and the d-axis current correction amount is obtained from the obtained q-axis voltage saturation amount and the rotation angular velocity. Further, a d-axis voltage saturation amount is obtained from a deviation between the d-axis voltage component and the d-axis voltage command, and a q-axis current correction amount is obtained from the obtained d-axis voltage saturation amount and the rotation angular velocity. Then, correction is applied to the d-axis and q-axis current commands output from the d/q-axis current command generator using the calculated d-axis and q-axis current correction amounts. According to this configuration, since both torque control in the permanent magnet synchronous motor and stable operation in a high-speed operation region can be realized, voltage saturation can be suppressed from occurring during high-speed operation, stable operation can be realized, and stability of control can be greatly improved.

Patent document 1: international publication No. 03/009463 pamphlet

Patent document 2: japanese patent laid-open No. 2000-116198

Disclosure of Invention

However, while the accuracy of torque control by the field weakening control described above is less problematic because SPM motors in permanent magnet synchronous motors have been used in many cases in the past, in recent years, IPM motors that do not cause the problem of magnet separation have begun to be used in large quantities with the transition of high-speed operation of permanent magnet motors, which has caused problems.

That is, in the SPM motor, since the torque is generated based on the equation (1), even if the current commands of the d-axis and the q-axis outputted from the d/q-axis current command generator are corrected later, only the amount of change in the current command of the q-axis affects the accuracy of the torque control. Therefore, the accuracy of the torque control is deteriorated not to a level that causes a problem in actual use.

However, in the IPM motor, since the torque is generated based on equation (3), if the d-axis and q-axis current commands output from the d/q-axis current command generator are corrected later, the amount of change in the current commands of both of them affects the accuracy of the torque control. Therefore, the accuracy of torque control may be reduced to a greater extent than torque control when using an SPM motor.

In addition, in the IPM motor, it is generally known that the operation efficiency is improved by applying an appropriate d-axis current according to the operation condition. Therefore, the d-axis current command output from the d/q-axis current command generator may be corrected for the purpose of improving the operating efficiency of the IPM motor. In this case, the accuracy of torque control is somewhat lowered not only in the high-speed operation but also in the low-speed operation and the medium-speed operation.

In order to solve this problem, for example, patent document 2 (embodiment 4) proposes a method for stably outputting the maximum torque under the condition that the motor terminal voltage is constant during the high-speed operation, and therefore, if this method is used, the d/q-axis current command generator can be configured in consideration of the fact that the voltage saturation does not occur during the high-speed operation.

However, in the d/q-axis current command generator to which the technique described in patent document 2 is applied, it is necessary to generate a d-axis current command and a q-axis current command that satisfy both a voltage relational expression based on an equivalent circuit of a motor and a torque relational expression shown by equation (3), and therefore, a very complicated operation is required, which causes a problem that a load on a product CPU becomes very large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a permanent magnet synchronous motor, which can perform torque control with high accuracy not only in low-speed operation and medium-speed operation but also in high-speed operation, regardless of whether the permanent magnet synchronous motor is an SPM motor or an IPM motor, without increasing the load on the CPU of the product.

In order to achieve the above object, the present invention provides a control device for a permanent magnet synchronous motor, comprising: a d/q-axis current command generator for generating current commands for the d-axis and q-axis, respectively, based on a torque command inputted from the outside; and a current controller for generating, by proportional-integral control, respective voltage commands for d-axis and q-axis for causing respective currents for d-axis and q-axis actually flowing in the permanent magnet synchronous motor to coincide with respective current correction commands for d-axis and q-axis, which are deviations between the respective current commands for d-axis and q-axis and respective current correction amounts for d-axis and q-axis corresponding thereto, the control device for the permanent magnet synchronous motor is characterized by comprising a torque correction circuit for generating a torque correction command based on a current phase of the respective current correction commands for d-axis and q-axis and the torque command, and supplying the torque correction command to the d/q-axis current command generator in place of the torque command.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the torque command inputted from the outside is not directly supplied to the d/q-axis current command generator, but is inputted to the additional torque correction circuit. The additional torque correction circuit generates a torque correction command using a torque command input from the outside thereof and the corrected current phases of the current commands for the d-axis and the q-axis, and supplies the torque correction command to the d/q-axis current command generator with a small amount of computation. Accordingly, the d/q-axis current command generator can generate the respective current commands of the d-axis and the q-axis in a form reflecting the actual operating state, and therefore, regardless of whether the permanent magnet synchronous motor is an SPM motor or an IPM motor, it is possible to generate appropriate respective current commands of the d-axis and the q-axis not only at the time of low-speed operation and at the time of medium-speed operation but also at the time of high-speed operation. That is, the present invention achieves an effect that torque control can be performed with high accuracy over the entire operating region without increasing the load on the product CPU.

Drawings

Fig. 1 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 1 of the present invention.

Fig. 2 is a block diagram showing a general configuration example of a control device for performing field weakening control of a permanent magnet synchronous motor.

FIG. 3 is a graph showing the torque correction coefficient k shown in FIG. 1₁A diagram of an example of the table data of (1).

Fig. 4 is a characteristic diagram showing the operation characteristics when embodiment 1 is applied to an IPM motor, compared with the conventional example.

Fig. 5 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 2 of the present invention.

FIG. 6 shows the torque correction command T shown in FIG. 5_m ^*cmd is a diagram of an example of table data.

Fig. 7 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 3 of the present invention.

Fig. 8 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 4 of the present invention.

Description of the reference numerals

1 current phase arithmetic unit

2. 4 torque corrector

3a, 3b, 3c multiplier

5 current amplitude rate of change arithmetic unit

9 d/q axis current command generator

10. 11, 12, 13 subtracter

14 d-axis current controller

15 q-axis current controller

16 two-phase three-phase coordinate converter

17 PWM inverter

18 permanent magnet synchronous motor

19a, 19b, 19c current detector

20 three-phase two-phase coordinate transformer

21 speed detector

22 coefficient device

23 integrator

Detailed Description

Hereinafter, preferred embodiments of a control device for a permanent magnet synchronous motor according to the present invention will be described in detail with reference to the accompanying drawings.

Embodiment mode 1

Fig. 1 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 1 of the present invention. Fig. 2 is a block diagram showing a general configuration example of a control device for performing field weakening control of a permanent magnet synchronous motor.

The essential parts (torque correction circuit) of the control device for the permanent magnet synchronous motor according to embodiment 1 shown in fig. 1 are constituted by a current phase calculator 1, a torque corrector 2, and a multiplier 3a, which are added to a conventional control device for field weakening control, which is the object of the present invention shown in fig. 2.

Here, in order to facilitate understanding of the present invention, first, the configuration and operation of a conventional control device that performs field weakening control, which is the object of the present invention, will be briefly described with reference to fig. 2, and then, with reference to fig. 1, the operation of the essential structure of the control device according to embodiment 1 will be described.

In fig. 2, a conventional control device for performing field weakening control includes, as a configuration for controlling a permanent magnet synchronous motor (PM) 18: a d/q-axis current command generator 9, subtracters 10, 11, 12, 13, a d-axis current controller 14, a q-axis current controller 15, a two-phase three-phase coordinate converter 16, a PWM inverter 17, current detectors 19a, 19b, 19c, a three-phase two-phase coordinate converter 20, a speed detector 21, a coefficient device 22, and an integrator 23.

The PWM inverter 17 is based on a voltage command V input from the two-phase three-phase coordinate converter 16_U ^*、V_V ^*、V_W ^*And generates drive power to be supplied to the permanent magnet synchronous motor 18. In addition, V_dcIs the bus voltage.

The speed detector 21 detects the rotational speed ω of the driven permanent magnet synchronous motor 18_r. The coefficient 22 is based on the rotation speed ω detected by the speed detector 21_rCalculating the angular velocity ω of rotation of the dq-axis coordinate₁. The integrator 23 calculates the rotational angular velocity ω of the dq-axis coordinate calculated by the coefficient 22₁The integration is performed, and the result is output to the two-phase three-phase coordinate converter 16 and the three-phase two-phase coordinate converter 20 as a phase angle θ of dq-axis coordinates.

The current detectors 19a, 19b, and 19c detect a motor drive current i supplied from the PWM inverter 17 to the permanent magnet synchronous motor 18_U、i_V、i_WAnd outputs it to the three-phase and two-phase coordinate converter 20.

Three-phase two-phase coordinate converter 20 converts motor drive current i detected by current detectors 19a, 19b, and 19b based on phase angle θ of dq-axis coordinate input from integrator 23_U、i_V、i_WConversion to d-axis current i on dq-axis coordinates_dAnd q-axis current i_qAnd outputs them to the respective subtractors 12, 13.

d/q-axis current command generator 9 generates a command according to an arbitrary torque command T inputted from the outside_m ^*Then, the d-axis current command i is generated on the dq-axis coordinate which is 2 axes that are rotational and orthogonal by performing the calculation of the above equation (2) or equation (3)_d ^*And q-axis current command i_q ^*D-axis current command i_d ^*Outputs a q-axis current command i to one input terminal of the subtractor 10_q ^*And is output to one input terminal of the subtractor 11.

The d-axis current correction amount Δ i is input to the other input terminal of the subtractor 10_d ^*The q-axis current correction amount Δ i is input to the other input terminal of the subtractor 11_q ^*. Although the d-axis current correction amount Δ i is not shown_d ^*And q-axis current correction amount Δ i_q ^*But it is generated by the method proposed in the patent document 1 (fig. 11). And will not be described repeatedly herein.

Subtractor 10 gives d-axis current instruction i_d ^*And d-axis current correction Δ i_d ^*The deviation between them is calculated and the result is used as d-axis current correction command i_d ^*cmd is output to one input terminal of the subtractor 12. A d-axis current from a three-phase to two-phase coordinate converter 20 is input to the other input terminal of the subtractor 12i_d. The subtractor 11 also outputs a q-axis current command i_q ^*And q-axis current correction amount Δ i_q ^*The deviation between the q-axis current and the q-axis current is calculated and the result is used as a q-axis current correction command i_q ^*cmd is output to one input terminal of the subtractor 13. The q-axis current i from the three-phase two-phase coordinate converter 20 is input to the other input terminal of the subtractor 13_q。

The subtractor 12 corrects the d-axis current by the command i_d ^*cmd and d-axis current i_dThe deviation between them is calculated and the result is taken as the current deviation e_idAnd output to the d-axis current controller 14. In addition, the subtractor 13 corrects the q-axis current correction command i_q ^*cmd and q-axis currents i_qThe deviation between them is calculated and the result is taken as the current deviation e_iqAnd outputs to the q-axis current controller 15.

The d-axis current controller 14 and the q-axis current controller 15 are each a proportional-integral (PI) controller that performs PI control. That is, the d-axis current controller 14 and the q-axis current controller 15 each generate the d-axis voltage command V by PI control_d ^*Q-axis voltage command V_q ^*And outputs them to a two-phase three-phase coordinate converter 16, in which a d-axis voltage command V is given_d ^*Q-axis voltage command V_q ^*Is to make the current inputted from subtracters 12 and 13 deviate e_id、e_iqThe operation amount becomes 0.

The two-phase three-phase coordinate converter 16 outputs the d-axis voltage command V from the d-axis current controller 14 and the q-axis current controller 15 based on the phase angle θ of the dq-axis coordinate input from the integrator 23_d ^*Q-axis voltage command V_q ^*Converted into a voltage command V_U ^*、V_V ^*、V_W ^*And outputs them to the PWM inverter 17.

As described above, in the vector control for the field weakening control, the actual direction is permanently controlled by the current controllers (the d-axis current controller 14 and the q-axis current controller 15)D-axis current i supplied by magnet synchronous motor 18_dAnd q-axis current i_qControl is performed so that they are respectively associated with d-axis current correction commands i_d ^*cmd and q-axis current correction command i_q ^*cmd is consistent.

Next, a main structure of the control device according to embodiment 1 will be described with reference to fig. 1. The current phase arithmetic unit 1 inputs the outputs of the subtractors 10 and 11 (d-axis current correction command i)_d ^*cmd, q-axis current correction command i_q ^*cmd) and phase of the current by beta_iAnd outputs to the torque corrector 2.

The torque corrector 2 receives an external torque correction command T_m ^*And a current phase beta from the current phase operator 1_iCorrecting the torque by a coefficient k₁And outputs to the multiplier 3 a.

The multiplier 3a receives an external torque command T_m ^*And a torque correction coefficient k from the torque corrector 2₁Correcting the torque by the command T_m ^*cmd is output to the d/q axis current command generator 9.

Next, the operation of the essential part of the control device according to embodiment 1 will be described. The d/q-axis current command generator 9 is originally provided for torque control of the permanent magnet synchronous motor 18, but needs to perform field weakening control in order to suppress voltage saturation during high-speed operation and to realize stable operation.

Therefore, as shown in fig. 2, the correction amount Δ i of the supplied d-axis current is used_d ^*And q-axis current correction amount [ delta ] i_q ^*For the d-axis current command i outputted from the d/q-axis current command generator 9_d ^*And q-axis current command i_q ^*And (5) a structure for performing correction. As described above, particularly in the IPM motor, the generated torque greatly changes, and the accuracy of torque control is lowered. This is described above.

Therefore, in embodiment 1In order to realize high-precision torque control, the external torque command T is not directly applied_m ^*The corrected current commands for the d-axis and q-axis (d-axis current correction command i) are supplied to the d/q-axis current command generator 9_d ^*cmd, q-axis current correction command i_q ^*cmd) current phase β_iFor a torque command T from the outside_m ^*The correction is applied, and the correction result is sent to the d/q-axis current command generator 9.

That is, the current phase computing unit 1 uses the d-axis current correction command i output from the subtractor 10 in the following expression (4)_d ^*cmd and q-axis current correction command i output by the subtractor 11_q ^*cmd, calculating the current phase β_iAnd outputs it to the torque corrector 2.

[ equation 4]

The torque corrector 2 is based on a torque command T from the outside_m ^*And a current phase beta from the current phase operator 1_iGenerating a torque correction coefficient k₁And outputs it to one input terminal of the multiplier 3 a. In addition, since the torque correction coefficient k₁Since it can be determined by a test in advance, it can be stored in the memory as table data. This method is used in embodiment 1.

FIG. 3 shows the torque correction factor k shown in FIG. 1₁Watch (A)A graph of an example of data. In FIG. 3, the abscissa represents the torque command T_m ^*[％]The vertical axis is the torque correction coefficient k₁. Shows a phase β with the current_i[°]A plurality of characteristic curves (in FIG. 3, β) corresponding to the value of (c)_i＝60[°]、β_i＝50[°]、β_i＝40[°]、β_i＝30[°]、β_i＝15[°]、β_i＝0[°]These six strips). These characteristic curves are torque command T_m ^*And current phase beta_iThe values of (2) are input and generated by performing interpolation or the like as necessary.

The torque corrector 2 is configured to provide an external torque command T_m ^*And a current phase beta from the current command generator 1_iThe values of (a) are inputted as address information into a memory for storing table data shown in FIG. 3, and the torque correction coefficient k obtained on the vertical axis is extracted₁And outputs it to the multiplier 3 a. Of course, the torque corrector 2 may store the table data shown in fig. 3 as a function, and may derive the torque correction coefficient k by calculation₁。

The multiplier 3a gives a torque command T from the outside_m ^*And a torque correction coefficient k from the torque corrector 2₁Performing multiplication, and using the multiplication result as torque correction command T_m ^*cmd, and outputs to the d/q axis current command generator 9.

As described above, the correction circuit (the current phase calculator 1, the torque corrector 2, and the multiplier 3a) to be added has a small calculation amount, and thus it can be said that the increase in load applied to the product CPU is small.

In embodiment 1, the d/q-axis current command generator 9 is substituted for the torque command T from the outside_m ^*According to the corrected torque correction command T_m ^*cmd generates d-axis current command i_d ^*And q-axis current command i_q ^*. This makes it possible to obtain the operation characteristics shown in fig. 4, for example.

Fig. 4 is a characteristic diagram showing the operation characteristics when the IPM motor according to embodiment 1 is applied, compared with the conventional example. Fig. 4 shows the respective operating characteristics of the high-speed operation, the medium-speed operation, and the low-speed operation in the case where embodiment 1 (fig. 1) is applied, and the respective operating characteristics of the high-speed operation, the medium-speed operation, and the low-speed operation in the case where the conventional example (fig. 2) is applied.

In fig. 4, the horizontal axis represents the torque command [% ], and the vertical axis represents the torque error (accuracy) [% ]. The operation characteristics shown in fig. 4 are obtained by plotting the magnitude of the torque command obtained on the horizontal axis and the difference between the magnitude and the actually output torque value as a torque error. When the torque error is 0, the permanent magnet synchronous motor 18 outputs the torque command, and the torque control accuracy is optimized.

As shown in fig. 4, in the conventional example (fig. 2), the accuracy of the torque control is lowered when the high-speed operation is performed. In contrast, in embodiment 1 (fig. 1), torque control with high accuracy can be performed even when high-speed operation is performed. Further, it is found that the accuracy of torque control can be improved in embodiment 1 (fig. 1) even in low-speed operation and medium-speed operation.

According to embodiment 1 described above, the torque command T is not input from the outside_m ^*The voltage is supplied directly to the d/q-axis current command generator 9 and is input to an additional correction circuit. The added correction circuit uses the current phase beta of the corrected d-axis current command and q-axis current command with a small calculation amount_iDeriving a torque correction factor k₁Using the torque correction coefficient k₁For torque command T_m ^*Corrected and sent to the d/q-axis current command generator 9.

Thus, the d/q-axis current command generator 9 can generate the d-axis and q-axis current commands so as to reflect the actual operating state, and thus, regardless of whether the permanent magnet synchronous motor 18 is an SPM motor or an IPM motor, it is possible to generate appropriate d-axis and q-axis current commands not only during low-speed operation and medium-speed operation but also during high-speed operation. Thus, torque control can be performed with high accuracy over the entire operating region without increasing the load on the product CPU.

In addition, in embodiment 1, there is obtained an advantage that the d-axis current i actually flowing in the permanent magnet synchronous motor 18 is applied to equation (3)_dAnd q-axis current i_qThe torque value thus obtained is multiplied by the reciprocal of the torque correction coefficient k1, whereby the torque value actually generated can be estimated with high accuracy.

Embodiment mode 2

Fig. 5 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 1 of the present invention. In fig. 5, the same or equivalent components as those shown in fig. 1 (embodiment 1) are denoted by the same reference numerals. Here, the description will be focused on the portions related to embodiment 2.

A main part (torque correction circuit) of the control device for a permanent magnet synchronous motor according to embodiment 2 shown in fig. 5 is provided with a torque corrector 4 in place of the torque corrector 2 and the multiplier 3a in addition to the configuration shown in fig. 1 (embodiment 1). According to this configuration, a multiplier is not required, and thus the overall operation amount can be further reduced, and the load on the product CPU can be further reduced.

The torque corrector 4 is based on a torque command T from the outside_m ^*And a current phase beta from the current phase operator 1_iDirectly generating a torque correction command T_m ^*cmd, and outputs it to the d/q-axis current command generator 9. In addition, the command T is corrected due to the torque_m ^*The cmd can be obtained by a test in advance, and can be stored in the memory as table data. This method is used in embodiment 2.

FIG. 6 shows the torque correction command T shown in FIG. 5_m ^*cmd is a diagram of an example of table data. In FIG. 6, the horizontal axis represents the torque command T_m ^*[％]The vertical axis is a torque correction command T_m ^*cmd[％]. Shows a phase β with the current_i[°]A plurality of characteristic curves (in FIG. 6, β is represented by_i＝60[°]、β_i＝50[°]、β_i＝40[°]、β_i＝30[°]、β_i＝15[°]、β_i＝0[°]These six strips). These characteristic curves are torque command T_m ^*And current phase beta_iThe values of (2) are input and generated by performing interpolation or the like as necessary.

The torque corrector 4 is configured to provide an external torque command T_m ^*And a current phase beta from the current command generator 1_iThe values of (a) are inputted as address information into a memory for storing table data shown in FIG. 6, and the torque correction command T obtained on the vertical axis is taken out_m ^*cmd, and outputs the cmd to the d/q axis current command generator 9. Of course, the torque corrector 4 may store the table data shown in fig. 6 in the form of a function, and may derive the torque correction command T by calculation_m ^*cmd。

According to embodiment 2 described above, the same operation and effects as those of embodiment 1 are obtained, and the torque correction coefficient k is not obtained₁But directly obtains the torque correction command T_m ^*cmd makes it possible to further reduce the overall computation amount, and to reduce the load on the product CPU compared to embodiment 1.

Embodiment 3

Fig. 7 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 3 of the present invention. In fig. 7, the same or equivalent components as those shown in fig. 1 (embodiment 1) are denoted by the same reference numerals. Here, the description will be focused on the portions related to embodiment 3.

A main part (torque correction circuit) of the control device for the permanent magnet synchronous motor according to embodiment 3 shown in fig. 7 is a configuration shown in fig. 1 (embodiment 1), in addition to which a current amplitude change rate calculator 5 is added, and a multiplier 3b is provided instead of the multiplier 3 a.

The current amplitude change rate calculator 5 inputs a d-axis current command i_d ^*Q-axis current command i_q ^*D-axis current correction command i_d ^*cmd and q-axis current correction command i_q ^*cmd, torque correction factor (2 nd torque correction factor) k₂And outputs the result to the multiplier 3 b.

The multiplier 3b receives an external torque command T_m ^*Torque correction coefficient (1 st torque correction coefficient) k from torque corrector 2₁And a torque correction coefficient (2 nd torque correction coefficient) k from the current amplitude change rate calculator 5₂Correcting the torque by the command T_m ^*cmd is output to the d/q axis current command generator 9.

Next, the operation of the essential parts of the control device according to embodiment 3 will be described. In the embodiments 1 and 2 described above, the current commands (d-axis current correction command i) using the corrected d-axis and q-axis are shown_d ^*cmd, q-axis current correction command i_q ^*cmd) current phase β_iFor a torque command T from the outside_m ^*A method of applying the correction.

However, since the d-axis current correction amount Δ i is supplied_d ^*And q-axis current correction amount [ delta ] i_q ^*So not only the current phase β_iAnd of course, the current amplitude thereof. Under this influence, the torque changes, and the accuracy of torque control may be reduced.

Therefore, in embodiment 3, torque control with higher accuracy is realizedFurther, the amplitude change rate of each current command for the d-axis and the q-axis is used to provide a torque command T to the external_m ^*Further corrections are applied.

That is, the current amplitude change rate calculator 5 outputs the d-axis current command i_d ^*Q-axis current command i_q ^*D-axis current correction command i_d ^*cmd and q-axis current correction command i_q ^*cmd is applied to the following equation (5), and the rate of change between the current amplitude before correction and the current amplitude after correction is calculated and used as the torque correction command k₂And outputs the result to the multiplier 3 b.

[ equation 5]

The multiplier 3b outputs a torque command T from the outside_m ^*Torque correction coefficient k from torque corrector 2₁And a torque correction coefficient k from a current amplitude change rate calculator 5₂Performing multiplication, and using the multiplication result as torque correction command T_m ^*cmd, and outputs to the d/q axis current command generator 9.

According to the following formulaIn embodiment 3 described above, the current phase β of the d-axis current command and the q-axis current command after correction is used_iDeriving a torque correction factor k₁And the rate of change of the current amplitude before and after the correction of the d-axis current command and the q-axis current command is derived, and the torque command T is corrected based on both the rate of change of the current amplitude before and after the correction of the d-axis current command and the q-axis current command_m ^*And then transmitted to the d/q-axis current command generator 9, thereby enabling torque control with higher accuracy than in embodiments 1 and 2.

Embodiment 4

Fig. 8 is a block diagram showing a main configuration of a control device for a permanent magnet synchronous motor according to embodiment 4 of the present invention. In fig. 8, the same or equivalent components as those shown in fig. 7 (embodiment 3) are denoted by the same reference numerals. Here, the description will be focused on the portion related to embodiment 4.

A main part (torque correction circuit) of the control device for a permanent magnet synchronous motor according to embodiment 4 shown in fig. 8 is a configuration shown in fig. 7 (embodiment 3), in which a torque corrector 4 shown in fig. 5 (embodiment 2) is provided in place of the torque corrector 2, and a multiplier 3c is provided in place of the multiplier 3 b.

The torque corrector 4 receives an external torque command T_m ^*And a current phase beta from the current phase operator 1_iOutputs a torque correction command (1 st torque correction command) T_m ^*cmd。

The multiplier 3c receives a torque correction command (1 st torque correction command) T from the torque corrector 4_m ^*cmd, and a torque correction coefficient k from the current amplitude change rate calculator 5₂A torque correction command (2 nd torque correction command) T_m ^*cmd2 is output to d/q axis current command generator 9.

Next, the operation of the essential parts of the control device according to embodiment 3 will be described. The torque corrector 4 is as shown in the description of figure 5 (embodiment 2),according to the current phase beta from the current phase operator 1_iAnd a torque command T from outside_m ^*Directly applying the torque correction command (1 st torque correction command) T_m ^*cmd is output to the d/q axis current command generator 9. With this configuration, the load on the product CPU can be reduced as in embodiment 2.

The multiplier 3c multiplies a torque correction command (1 st torque correction command) T from the torque corrector 4_m ^*cmd, and a torque correction coefficient k from the current amplitude change rate calculator 5₂Multiplication is performed, and the multiplication result is used as a torque correction command (2 nd torque correction command) T_m ^*cmd2, to d/q axis current command generator 9.

As described above, according to embodiment 4, the operation and effect of embodiment 3 are obtained, and the torque correction coefficient k is not obtained as in fig. 7 (embodiment 3)₁Instead, the torque correction command (1 st torque correction command) T is directly obtained_m ^*cmd can reduce the overall computation amount, and can reduce the load on the product CPU compared to embodiment 3.

Industrial applicability

As described above, the control device of a permanent magnet synchronous motor according to the present invention is useful as a control device of a permanent magnet synchronous motor that can perform torque control with high accuracy not only in low-speed operation and medium-speed operation but also in high-speed operation, regardless of whether the permanent magnet synchronous motor is an SPM motor or an IPM motor, without increasing the load on the CPU of the product.

Claims (6)

1. A control device for a permanent magnet synchronous motor, comprising: a d/q-axis current command generator for generating current commands for the d-axis and q-axis, respectively, based on a torque command inputted from the outside; and a current controller for generating d-axis and q-axis voltage commands for causing d-axis and q-axis currents actually flowing in the permanent magnet synchronous motor to coincide with d-axis and q-axis current correction commands, which are deviations between the d-axis and q-axis current commands and corresponding d-axis and q-axis current correction amounts,

the control device of the permanent magnet synchronous motor is characterized in that,

the electric current correction device includes a torque correction circuit that generates a torque correction command based on the current phase of each of the current correction commands for the d-axis and the q-axis and the torque command, and supplies the torque correction command to the d/q-axis current command generator in place of the torque command.

2. The control device of a permanent magnet synchronous motor according to claim 1,

the torque correction circuit has: a current phase calculator for calculating a current phase from each of the current correction commands for the d-axis and the q-axis; a torque corrector that outputs a torque correction coefficient according to the torque command and the current phase; and a multiplier that multiplies the torque command by the torque correction coefficient to output the torque correction command.

3. The control device of a permanent magnet synchronous motor according to claim 1,

the torque correction circuit has: a current phase calculator for calculating a current phase from each of the current correction commands for the d-axis and the q-axis; and a torque corrector that outputs the torque correction command according to the torque command and the current phase.

4. A control device for a permanent magnet synchronous motor, comprising: a d/q-axis current command generator for generating current commands for the d-axis and q-axis, respectively, based on a torque command inputted from the outside; and a current controller for generating d-axis and q-axis voltage commands for causing d-axis and q-axis currents actually flowing in the permanent magnet synchronous motor to coincide with d-axis and q-axis current correction commands, which are deviations between the d-axis and q-axis current commands and corresponding d-axis and q-axis current correction amounts,

the control device of the permanent magnet synchronous motor is characterized in that,

the d/q axis current command generator includes a torque correction circuit that generates a torque correction command based on a current phase and a current amplitude of each of the d and q axis current correction commands and the torque command, and supplies the torque correction command to the d/q axis current command generator in place of the torque command.

5. The control device of a permanent magnet synchronous motor according to claim 4,

the torque correction circuit has: a current phase calculator for calculating a current phase from each of the current correction commands for the d-axis and the q-axis; a torque corrector outputting a 1 st torque correction coefficient according to the torque command and the current phase; a current amplitude change rate calculator for calculating a change rate between the amplitude of each of the current commands for the d-axis and the q-axis and the amplitude of each of the current correction commands for the d-axis and the q-axis, and outputting the change rate as a 2 nd torque correction coefficient; and a multiplier that multiplies the torque command, the 1 st torque correction coefficient, and the 2 nd torque correction coefficient to output the torque correction command.

6. The control device of a permanent magnet synchronous motor according to claim 4,

the torque correction circuit has: a current phase calculator for calculating a current phase from each of the current correction commands for the d-axis and the q-axis; a torque corrector outputting a 1 st torque correction command according to the torque command and the current phase; a current amplitude change rate calculator that calculates a change rate between the amplitude of each of the current commands for the d-axis and the q-axis and the amplitude of each of the current correction commands for the d-axis and the q-axis, and outputs the change rate as a torque correction coefficient; and a multiplier that multiplies the torque command, the 1 st torque correction command, and the torque correction coefficient to obtain a 2 nd torque correction command, and outputs the 2 nd torque correction command as the torque correction command to be supplied to the d/q-axis current command generator.