JPH1189277A - Controller of reluctance motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the coil current of a reluctance motor accurately and independently without using a current sensor. SOLUTION: A controller is equipped with a current command value operating circuit 1 which operates the current command value to each exciting coil of a reluctance motor 5 from the angle of rotation of a motor detected with an angle-of-rotation sensor 6 and a torque command value; a voltage command value operating circuit 2 which operates the voltage command value to each exciting coil from this current command value, the angle of rotation of the motor, and a motor parameter; a PWM pulse command value making circuit 3 which makes a PWM pulse command value, based on this voltage command value; and a power converting circuit 4 which generates a PWM pulse signal in accordance with this PWM pulse command value, and performs current application to each exciting coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control apparatus for a reluctance motor, and more particularly, to a control apparatus for a reluctance motor that controls a motor current without using a current sensor.

[0002]

2. Description of the Related Art First, the driving principle of a reluctance motor will be described. The reluctance motor has salient poles on the rotor and the stator, respectively.
One excitation coil is wound as a set to form one phase. When a current is supplied to the exciting coil, the reluctance of the phase changes and the rotor is attracted to a position where the reluctance is minimized. The rotor is rotated by the suction force.

Next, control of output torque of such a reluctance motor will be described for a general three-phase case. The output torque T of the reluctance motor is described by equation (1). T = (1/2) ia ² (dLa / dθ) + (1/2) ib ² (dLb / dθ) + (1/2) ic ² (dLc / dθ) + ia ib (dMab / dθ) + ib ic ( dMbc / dθ) + icia (dMca / dθ) (1) La: a-phase self-inductance Lb: b-phase self-inductance Lc: c-phase self-inductance Mab: ab-phase mutual inductance Mbc: bc-phase mutual inductance Mca: ca Phase mutual inductance ia: a-phase coil current ib: b-phase coil current ic: c-phase coil electrolysis θ: motor rotation angle In a reluctance motor, self-inductance L is usually sufficiently larger than mutual inductance M, and motor rotation angle (DL / dθ) is also sufficiently larger than the differential value of the mutual inductance (dM / dθ) with respect to (rotor position). In many cases, ignoring the problem does not cause a problem, and the output torque T can be approximated by Expression (2).

T = (1/2) ia ² (dLa / dθ) + (1/2) ib ² (dLb / dθ) + (1/2) ic ² (dLc / dθ) (2) , The output torque of the reluctance motor is given by equation (3)
Is expressed in the form of the sum of the torques generated in the respective phases, as shown in the following equation. And the square of the coil current (i ² ).

[0005] ^{T = ΣTk (0121 a, b} , c) ··· (3) Tk = (1/2 ) ik 2 (dLk / dθ) (0121 a, b, c) ··· (4) rotation angle of the three-phase four-pole reluctance motor in FIGS. 1 (a) And the relationship between self-inductance. When performing torque control, for example, when outputting a positive torque, a phase, b
The phase in which the amount of change in the self-inductance with respect to the motor rotation angle θ is positive is selected from the three phases of phase c and phase c, and a current may be passed. The current command value for reducing the time change of the current of each phase so that the total torque by the three-phase coils matches the command value and the peak voltage can be small is, for example, FIG.
(B). Here, there is a section in which current flows in two phases. In this section, the total torque of the two phases is the output torque of the motor. Since the output torque is the sum of the values proportional to the square of the current of each phase as shown in the equation (2), when the current flows through a plurality of phases, the output torque is the same even if the total current value is the same. I can't say that. That is,
In order to control the output torque of the reluctance motor, it is necessary to control the current of each phase independently.

By the way, in order to control the current of the reluctance motor, it is general to provide a means for detecting the motor current for each phase and to perform feedback control of the current. However, a current sensor used as a means for detecting a current is expensive and relatively large in size. In particular, in a control device for a small-output motor, there is a demand to reduce the number of current sensors in terms of both cost and size. As a countermeasure against this, there is one proposed in, for example, JP-A-6-351289. In this example, the total current of the three phases is detected by using one current sensor, and the coil current of each phase is controlled by one current control loop.

[0007]

However, in the above-mentioned prior art, although the number of current sensors is reduced, the current sensors are still used. Further, since the total current of three phases is detected and the current is controlled by one control loop, the current of each phase cannot be controlled independently. Therefore, there is a problem that the control accuracy of the output torque is reduced when a current is supplied to a plurality of phases simultaneously.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and eliminates the need for coil current detection means and enables independent control of the current of each phase. It is an object of the present invention to provide a control device.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a rotation angle detecting means for detecting a rotation angle of a motor, and a command in accordance with the detected motor rotation angle. Current command value calculating means for calculating a current command value to the excitation coil of each phase so as to output a torque according to a value; and a motor command for each phase based on the calculated current command value and the detected motor rotation angle and motor parameters. Command value calculating means for calculating a voltage command value to the exciting coil of the first embodiment, and PWM for generating a PWM pulse command value based on the calculated voltage command value
It is characterized by comprising a pulse command value generating means, and a driving means for generating a PWM pulse signal in accordance with the generated PWM pulse command value and energizing the excitation coils of each phase.

In the reluctance motor control device having the above-described configuration, the voltage required to follow the current command value to the exciting coil of each phase of the motor is calculated from the motor parameters corresponding to the motor rotation angle. A command value of a PWM pulse signal for applying a voltage value to the excitation coil of each phase is created to control the energization of the excitation coil. Claim 2
In the invention described in the above, the voltage command value calculating means is calculated by the inductance calculating means for determining at least the inductance of the exciting coil of each phase according to the motor rotation angle, and the calculated inductance value and the current command value calculating means are calculated. Magnetic flux command value calculating means for calculating a magnetic flux command value of the exciting coil of each phase from the current command value obtained; and a magnetic flux command value change amount calculating means for calculating a target response of the magnetic flux and its time change amount from the magnetic flux command value. And an adder for calculating the voltage command value by calculating the sum of the product of the resistance value of the exciting coil of each phase and the current command value and the calculated time change of the target response of the magnetic flux. The configuration was adopted.

In the reluctance motor control device having such a configuration, the target response of the magnetic flux and its time change amount are calculated from the current command value, and the voltage drop due to the resistance is calculated. The sum of the voltage drops is determined and used as a voltage command value. In the invention according to claim 3, the inductance calculating means calculates a self-inductance of the exciting coil, and the magnetic flux command value calculating means calculates a magnetic flux command value from the self-inductance of the exciting coil and the current command value. I made it.

[0012] In the invention described in claim 4, the inductance calculating means is configured to calculate an inductance according to a motor rotation angle and a current command value. In the reluctance motor control device having such a configuration, the current command value and the inductance value according to the motor rotation angle are used for calculating the voltage command value. In the invention as set forth in claim 5, the PWM pulse command value creating means determines the voltage command value and the applied voltage from a relationship between a PWM pulse signal generated from the driving means and an applied voltage applied to an exciting coil. The PWM pulse command value is created so that the values of the two are equal.

In the invention according to claim 6, the PWM pulse command value creating means sets the on-duty of the PWM pulse command value to 0 when the current command value is 0.

[0014]

According to the first aspect of the present invention, a voltage command value is calculated using a motor parameter from a current command value calculated so as to obtain a desired output torque according to the motor rotation angle, By generating a PWM pulse signal based on the voltage command value and controlling the energization for each phase of the excitation coil, a current that follows the current command value without flowing the current is supplied to the excitation coil of each phase. The motor current can be accurately controlled without using a current sensor, and the current is controlled for each phase of the exciting coil, so that the output torque can be controlled with high accuracy.

According to the second aspect of the present invention, a magnetic flux command value of the exciting coil is calculated from the inductance of the exciting coil and the current command value, and a target response of the magnetic flux and its time change amount are calculated from the magnetic flux command value. Since the voltage command value is calculated from the sum of the time variation of the target response and the voltage drop due to the resistance of the exciting coil, the voltage command value for achieving the desired response can be easily calculated. is there.

According to the third aspect of the present invention, by calculating the magnetic flux command value based on the self-inductance of the exciting coil, a complicated calculation including the magnetic flux due to the mutual inductance that is sufficiently smaller than the magnetic flux due to the self-inductance can be performed. Therefore, the calculation of the voltage command value can be further simplified. According to the fourth aspect of the present invention, when calculating the inductance used for calculating the voltage command value, the current command value is used in addition to the motor rotation angle, so that the current flows through the exciting coil even in a region where magnetic saturation occurs. The current can follow the current command value.

According to the fifth aspect of the present invention, a voltage command value due to a rise or fall response delay of a switching element for controlling energization of an excitation coil in a drive circuit and P
The deviation from the WM voltage can be corrected. According to the invention according to claim 6, when the current command value is 0, the on-duty of the PWM pulse command value is set to 0. Therefore, when a current flows through the exciting coil, the negative maximum voltage is reduced. When the current is applied to the exciting coil and no current is flowing, no voltage is applied to the exciting coil, so that the current of the exciting coil can quickly follow the current command value.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control apparatus for a reluctance motor according to the present invention will be described below. FIG.
FIG. 1 is a block diagram showing an entire configuration of a first embodiment of a reluctance motor control device according to the present invention.

In FIG. 2, the control device of the present embodiment comprises:
Torque command value T given from outside ^*So that
Rotation angle detection that detects the rotation angle θ of the reluctance motor 5
Motor rotation output from rotation angle sensor 6 as means
Each phase (a phase, b phase, c phase in this embodiment) using the angle θ
Current command value ia^*, Ib^*, Ic^*Current finger to calculate
Command value calculation circuit 1 and these current command values ia^*, Ib
 ^*, Ic^*And the motor rotation angle θ
Voltage command value Va using the parameters of^*, Vb ^*,
Vc^*And a voltage command value calculation circuit 2 for calculating
Pressure command value Va^*, Vb^*, Vc^*Voltage equivalent to
PWM pulse command for applying to the excitation coil of each phase
Value Vsa^*, Vsb^*, Vsc^*PWM pulse command to calculate
Value creation circuit 3 and PWM pulse command value Vsa^*, Vsb^*,
Vsc^*Excitation coil of each phase of the reluctance motor 5 according to
And a power conversion circuit 4 as driving means for supplying power to the
It is configured with.

Next, the voltage command value calculation circuit 2 of the present embodiment
Will be described. First, before describing the circuit configuration, the relationship between the voltage and the current of the reluctance motor will be described. The relationship between the current and the voltage of the exciting coil of each phase of the reluctance motor is described by equations (5) to (7). Va = Ria + [d (La · ia) / dt] + [d (Mab · ib) / dt] + [d (Mca · ic) / dt] (5) Vb = Rib + [d (Lb) Ib) / dt] + [d (Mbc.ic) / dt] + [d (Mab.ia) / dt] (6) Vc = Ric + [d (Lc.ic) / dt] + [ d (Mca · ia) / dt] + [d (Mbc · ib) / dt] (7) Va: a-phase applied voltage Vb: b-phase applied voltage Vc; c-phase applied voltage ia: a-phase current ib : B-phase current 1c: c-phase current R: winding resistance In formulas (5) to (7), the first and second terms are generally sufficiently larger than the third and fourth terms. (8)-
It can be approximated as (10).

Va = Ria + [d (La · ia) / dt] (8) Vb = Rib + [d (Lb · ib) / dt] (9) Vc = Ric + [d ( Lc · ic) / dt] (10) The aa, b, and c phase current command values of the reluctance motor are ia ^* , ib ^* , ic ^* , respectively, and the voltage command values are Va ^* , V
Assuming that b ^* and Vc ^* , the voltage command value from the current command value is
It can be obtained as in the following equations (11) to (13).

Va^*= Ria^*+ [D (La · ia^*) / Dt] (11) Vb^*= Rib^*+ [D (Lb · ib^*) / Dt] (12) Vc^*= Ric^*+ [D (Lc · ic^*) / Dt] (13) FIG. 3 shows the voltage command value calculation circuit 2 of the present embodiment in detail.
FIG. In FIG. 3, a voltage command value calculation circuit 2
Is the voltage command value Va for the a-phase, b-phase, and c-phase ^*, Vb^*, Vc
 ^*2A, 2B, and 2C that respectively calculate
1 (a), the phase of each phase changes with respect to the motor rotation angle θ.
The data of the inductances La, Lb, Lc are stored.
Table map 2-1. Each performance
The arithmetic units 2A, 2B and 2C have the same configuration.
Hereinafter, only the a-phase operation unit 2A will be described.

The arithmetic unit 2A is a multiplier for obtaining a magnetic flux command value φa ^* from the inductance La and the current command value ia ^* retrieved from the table map 2-1 according to the rotation angle θ detected by each rotation sensor 6. 2-2 and the magnetic flux command value φa ^*
From the magnetic flux target response φma ^* and its time derivative d (φma
^* ) / Dt to determine the filter 2-3 and the current command value ia
^* Is multiplied by the resistance value R of the exciting coil to obtain a voltage command value R · ia ^{* corresponding} to the resistance.
^* The time differential value d (φma ^*) / dt and an adder 2-5 for obtaining the sum of the resistance of the voltage command value R · ia ^*, exciting the calculation result of the adder 2-5 a-phase It is configured to output as a voltage command value Va ^* for the coil.

FIG. 4 shows a power conversion circuit 4 according to this embodiment.
Is shown. In FIG. 4, when a PWM pulse command value for each phase from the PWM pulse command value creation circuit 3 is input to the drive circuit 11, the drive circuit 11 generates a PWM pulse signal corresponding to the PWM pulse command value. Switching elements (MOSFET, etc.) 19 and 20, 2
By driving 1 and 22, and 23 and 24, the current flowing through the exciting coils 13, 14, and 15 of each phase is adjusted so as to match the current command value. In FIG. 4, 12 is a power supply, 16 to 18 are resistors, and 25 to 30 are diodes.

Next, the operation will be described. In order to obtain the command value T ^* of the output torque given from the outside, the current command values ia ^* , ib ^* , and ic ^* calculated by the current command value calculation circuit 1 according to the motor rotation angle? In order to make the current follow, it is necessary to calculate the voltage command values Va ^* , Vb ^* , and Vc ^* shown in the equations (11) to (13). Therefore, in the voltage command value calculation circuit 2, each calculation unit 2A
2C, the current command values ia ^* , ib ^* , ic ^* respectively input from the current command value calculation circuit 1 and the detected motor rotation angle θ are searched from the inductance data table map 2-1. From the inductances La, Lb, Lc of each phase, the magnetic flux command values φa ^* , φ
b ^* , φc ^* , and the magnetic flux command values φa ^* , φb ^* ,
.phi.c ^* of target response φma ^*, φmb ^*, time-differentiated value d for ^{φmc * (φma *) / dt} , d (φmb *) / dt, d
(Φmc ^* ) / dt is calculated, and this is calculated according to equations (11) to (13).
Is the voltage command value for the inductance at. Also,
The voltage command values Ria ^* , Rib ^* , Ric ^* for the resistance are:
It is determined from the product of the current command values ia ^* , ib ^* , ic ^* and the resistance value R. Then, the sum of these is calculated by the adder 2-5 to generate voltage command values Va ^* , Vb ^* , Vc ^* to be applied to the exciting coils 13 to 15 of each phase.

Here, if ωc in each of the filters of the calculation units 2A to 2C is increased, the desired magnetic flux responses φma ^* and φma ^*
mb ^*, φmc ^* of the time differential ^{d (φma *) / dt,} d (φmb
^* ) / Dt and d (φmc ^* ) / dt approach the time derivative of the magnetic flux command value. Therefore, if ωc is increased within the required current responsiveness range, it can be regarded as equivalent to the equations (11) to (13). By doing so, the voltage command values Va ^* , Vb ^* , which cause the respective exciting coil currents to follow the current command values ia ^* , ib ^* , ic ^* with a simple control system.
Vc can be calculated.

Then, the calculated voltage command value Va^*, V
b^*, Vc from the PWM pulse command value Vsa^*, Vsb^*, V
sc^*Is created, and the created PWM pulse command value Vsa^*,
Vsb ^*, Vsc^*Circuit 1 of the power conversion circuit 4 based on the
A PWM pulse signal is generated from 1 and an excitation coil of each phase is generated.
Power is supplied to 13 to 15. With such a configuration
Excitation coil for each phase without current sensor
Current can be controlled and output even when current is applied to multiple phases simultaneously
The torque can be controlled with high accuracy.

Incidentally, originally, the relationship between the voltage and the current is expressed by the following equation (5).
It is represented by a complicated equation as shown in (7). Therefore, if a mutual inductance data map is provided in addition to the self-inductance table map 2-1 in the same manner as in the present embodiment, the control system of the reluctance motor based on the equations (5) to (7) is configured. You can also. Next, a second embodiment will be described.

The overall configuration of the second embodiment is the same as that of the first embodiment shown in FIG. The difference of the second embodiment from the first embodiment is a table map containing the inductance data of the voltage command value calculation circuit 2, and FIG. 5 shows the voltage command value calculation circuit of the second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. FIG.
In this embodiment, the table map 2-1 'containing the inductance data of the present embodiment is configured to search the self-inductance data based on each motor rotation θ and the current command values ia ^* , ib ^* , and ic ^* .

When the current of the exciting coils 13 to 15 increases, saturation of magnetic flux occurs. In such a saturation region, the self-inductances La, Lb, and Lc change not only with the motor rotation angle θ but also with the current. Therefore, as in the control system of the present embodiment, the current command values ia ^* , ib ^* , i
From c ^* and the motor rotation angle θ, the excitation coils 13 to
If the configuration is such that the data of 15 self-inductances La, Lb, and Lc are retrieved, the current command values ia ^* , ib ^* , and ic ^* will match the actual current even in the region where magnetic saturation occurs. The control accuracy can be further improved.

Next, a third embodiment will be described. The overall configuration of the third embodiment is the same as that of the first embodiment shown in FIG. In the third embodiment, a PWM pulse command value creation circuit is different, and the operation of the PWM pulse command value creation circuit of the present embodiment will be described with reference to the flowchart of FIG. In the following, the phase a will be described, but the same applies to the other phases b and c.

First, the current command value ia ^* is read (step (1)). Next, it is determined whether or not the current command value ia ^* is 0 (step (2)). If the current command value ia ^* is not 0, the process proceeds to step (3). In step (3), a voltage command Va ^* is read. Next, a map containing the duty of the PWM pulse command value Vsa ^* with respect to the voltage command value Va ^* is referred to (step (5)). This map shows the voltage command value Va ^* and the a-phase excitation coil 13.
The duty of the PWM pulse command value that matches the equivalent voltage applied to the excitation coil is stored, and a deviation between the voltage command value and the equivalent voltage applied to the exciting coil can be corrected.

Here, the duty data stored in the map will be described in detail. FIG. 7 shows the PWM command signal Vsa
FIG. 5 is a diagram showing a relationship between ^{* and} an a-phase excitation coil applied voltage Va. When current is flowing through the exciting coil, PWM
When the command signal is ON, the voltage Von is applied to the exciting coil. On the other hand, when it is OFF, the voltage Voff is applied. However, when the power conversion circuit 4 of FIG. 4 is used, the voltages Von and Voff are expressed by Expressions (14) and (15).

Von = Vdc−2Vmoff (14) Voff = 1Vdc + 2Vdon (15) Vdc: DC power supply voltage of power conversion circuit Vmoff: ON resistance of switching element Vdon: forward voltage drop of diode However, switching element 19 , 20, a delay occurs in the rising and falling responses as shown in FIG. 7, and the duty of the PWM pulse command value Vsa ^* differs from the duty of the actual excitation coil applied voltage Va. Therefore, the equivalent voltage applied to the exciting coil that directly outputs the PWM pulse command value Vsa ^* corresponding to the voltage command value Va ^* differs. Therefore, in the present embodiment, in consideration of the response characteristics of the rising and falling of the switching element, for example, when there is a shift as shown in FIG. 7, the PWM command value Vsa ^* is compared with the voltage command value Va ^* . The duty data is created and mapped by taking measures to reduce the duty. This makes it possible to correct the deviation between the voltage command value caused by the response characteristics of the switching element and the equivalent voltage applied to the exciting coil.

Then, the PWM obtained in step (5)
The pulse command value is output to the power conversion circuit 4 (step (6)). On the other hand, when the current command value ia ^* is 0, P
The duty of the WM pulse command value is set to 0 (step (4)). As described above, if the duty of the PWM pulse command value is set to 0, the equation (15) is obtained when the current is flowing.
Is applied to the exciting coil, and the current decays fastest. When the current becomes zero, the voltage applied to the exciting coil becomes zero. Therefore, current followability is good and unnecessary switching is not required.

Then, the process proceeds to step (6) to output the PWM pulse command value of duty 0 calculated in step (4).

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a rotation angle of a reluctance motor and a self-inductance / current command value.

FIG. 2 is an overall configuration diagram of a first embodiment of a control device of the present invention.

FIG. 3 is a configuration diagram of a voltage command calculation circuit according to the first embodiment;

FIG. 4 is a configuration diagram of a power conversion circuit.

FIG. 5 is a configuration diagram of a voltage command calculation circuit according to a second embodiment of the present invention.

FIG. 6 is an operation flowchart of a PWM pulse command value creation circuit according to a third embodiment of the present invention;

FIG. 7 is a diagram showing a relationship between an excitation coil applied voltage and a PWM command signal.

[Explanation of symbols]

 1 Current command value calculation circuit 2 Voltage command value calculation circuit 3 PWM pulse command value creation circuit 4 Power conversion circuit 5 Reluctance motor 6 Rotation angle sensor

Claims (6)

[Claims] 1. A rotation angle detecting means for detecting a motor rotation angle, and calculating a current command value to an exciting coil of each phase so as to output a torque according to a command value according to the detected motor rotation angle. Voltage command value calculating means for calculating the voltage command value to the exciting coil of each phase from the calculated current command value and the detected motor rotation angle and motor parameters, and the calculated voltage PWM pulse command value generating means for generating a PWM pulse command value based on the command value; driving means for generating a PWM pulse signal in accordance with the generated PWM pulse command value and energizing the excitation coil of each phase; A control device for a reluctance motor, comprising: 2. The voltage command value calculating means calculates an inductance of each phase excitation coil corresponding to at least a motor rotation angle, and calculates the calculated inductance value and the current command value calculating means. A magnetic flux command value calculating means for calculating a magnetic flux command value of the exciting coil of each phase from the current command value; a magnetic flux command value change amount calculating means for calculating a target response of the magnetic flux from the magnetic flux command value and a time change amount thereof; An adding means for calculating the voltage command value by calculating a sum of a product of a resistance value of the exciting coil of each phase and the current command value and a time variation of the calculated magnetic flux target response; The control device for a reluctance motor according to claim 1, wherein: 3. The method according to claim 2, wherein the inductance calculating means calculates a self-inductance of the exciting coil, and the magnetic flux command value calculating means calculates a magnetic flux command value from the self-inductance of the exciting coil and a current command value. Claim 2
A reluctance motor control device according to any one of the preceding claims. 4. The reluctance motor control device according to claim 2, wherein said inductance calculating means calculates an inductance according to a motor rotation angle and a current command value. 5. The PWM pulse command value generating means, based on a relationship between a PWM pulse signal generated from the driving means and an applied voltage applied to an exciting coil, makes the voltage command value and the applied voltage equal. The reluctance motor control device according to any one of claims 1 to 4, wherein a PWM pulse command value is created. 6. The PWM pulse command value creation means sets the on-duty of the PWM pulse command value to 0 when the current command value is 0.
5. The control device for a reluctance motor according to any one of 5.