JP3528535B2 - Reluctance motor control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reluctance motor control device, and more particularly to a reluctance motor control device that controls a motor current without using a current sensor.

[0002]

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

Next, control of the 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 sulfur θ: Motor rotation angle In a reluctance motor, the self-inductance L is usually much larger than the mutual inductance M and the motor rotation angle is Since the derivative value (dL / dθ) of self-inductance with respect to (rotor position) is also sufficiently larger than the derivative value (dM / dθ) of mutual inductance, the term of mutual inductance is If you've seen no problem is large, the output torque T can be approximated by equation (2).

[0004] That is, the output torque of the reluctance motor is calculated by the equation (3).
The torque generated in each phase is expressed by the sum of the torques generated in each phase as shown in (4), and the torque generated in each phase is expressed by the differential value (dL / dθ) of the self-inductance with respect to the motor rotation angle It is proportional to the product of the coil current and the square (i ² ).

[0005] FIG. 1A shows the relationship between the rotation angle and the self-inductance of a 3-phase 4-pole reluctance motor. When performing torque control, for example, when outputting positive torque, a phase, b
It suffices to select a phase in which the amount of change in the self-inductance with respect to the motor rotation angle θ is positive from among the three phases, the phase and the c phase, and apply a current. The current command value for reducing the time change of the current of each phase so that the total torque by the coils of the three phases matches the command value and the peak voltage may be small is shown in FIG.
It becomes like (b). Here, there is a section in which current is applied to the two phases, but in this section, the sum of the torques for the two phases is the output torque of the motor. As shown in equation (2), the output torque is the sum of the values proportional to the square of the current of each phase. Therefore, when the current is applied to multiple phases, the output torque is the same even if the total current value is the same. I can't say it will. That is,
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 to perform feedback control of the current. However, a current sensor used as a means for detecting a current is expensive and has a relatively large size. Especially, in a control device for a low output motor, there is a demand to reduce the number of current sensors in terms of cost and size. As a countermeasure against this, there is, for example, one proposed in Japanese Patent Laid-Open No. 6-351289. In this example, it detects the total current of the three phases using one current sensor, and controls the phase of the coil current in 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. Moreover, 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 in that the control accuracy of the output torque is reduced when a current is simultaneously applied to a plurality of phases.

The present invention has been made in view of the above 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 of.

[0009]

In order to achieve the above object, in the invention described in claim 1, a rotation angle detecting means for detecting a rotation angle of a motor and a command according to the detected motor rotation angle are provided. Each phase is calculated from the current command value calculating means for calculating the current command value to the exciting coil of each phase so as to output the torque as valued, and the calculated current command value and the detected motor rotation angle and motor parameter. Voltage command value calculating means for calculating a voltage command value for the exciting coil of the, and PWM for generating a PWM pulse command value based on the calculated voltage command value
It is characterized by comprising pulse command value creation means and drive means for generating a PWM pulse signal according to the created PWM pulse command value and energizing the exciting coil of each phase.

In the reluctance motor control device having such a 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 parameter according to the motor rotation angle, and this calculation is performed. A command value of a PWM pulse signal for applying a voltage value to the exciting coil of each phase is created to control energization to the exciting coil. Claim 2
In the invention described in (1), the voltage command value calculation means is calculated by at least the inductance calculation means for obtaining 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 calculation means. Magnetic flux command value calculating means for calculating the magnetic flux command value of the exciting coil for each phase from the current command value, and magnetic flux command value change amount calculating means for calculating the target response of the magnetic flux and its time change amount from the magnetic flux command value. , An adding means 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 time variation of the calculated target response of the magnetic flux. It was configured.

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 to obtain the time change amount of the magnetic flux target response and the resistance change. The sum of the voltage drops is calculated and used as the voltage command value. In the invention according to claim 3, the inductance calculating means calculates the self-inductance of the exciting coil, and the magnetic flux command value calculating means calculates the magnetic flux command value from the self-inductance of the exciting coil and the current command value. I chose

According to another aspect of the present invention, the inductance calculation step calculates the inductance according to the motor rotation angle and the current command value. In the reluctance motor controller having such a configuration, the current command value and the inductance value according to the motor rotation angle are used to calculate the voltage command value. In the invention according to claim 5, the PWM pulse command value creating means determines the voltage command value and the applied voltage from the relationship between the PWM pulse signal generated from the driving means and the applied voltage applied to the exciting coil. The PWM pulse command values are created so that the values are equal to each other.

According to the sixth aspect of the present invention, 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, the voltage command value is calculated using the parameters of the motor from the current command value calculated so that the desired output torque is obtained according to the motor rotation angle, By generating a PWM pulse signal based on this voltage command value and controlling energization for each exciting coil of each phase, a current that follows the current command value without flowing a current is passed through the exciting coil of each phase. Since the motor current can be accurately controlled without using a current sensor, and the current is controlled for each exciting coil of each phase, the output torque can be accurately controlled.

According to the second aspect of the present invention, the magnetic flux command value of the exciting coil is calculated from the inductance of the exciting coil and the current command value, and the 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 change amount of the target response and the voltage drop due to the resistance of the exciting coil, it is possible to easily calculate the voltage command value that realizes the desired responsiveness. 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, which is sufficiently smaller than the magnetic flux due to the self-inductance. Therefore, the calculation of the voltage command value can be further simplified. According to the invention of claim 4, when the inductance used to calculate the voltage command value is calculated, the current command value is also used in addition to the motor rotation angle, so that the current flows in the exciting coil even in the region where magnetic saturation occurs. The current can be made to follow the current command value .

According to the fifth aspect of the invention, the voltage command value and P due to the response delay of the rising and falling of the switching element for controlling the energization of the exciting coil in the drive circuit and P
The deviation from the WM voltage can be corrected. According to the invention of claim 6, when the current command value is 0, the on-duty of the PWM pulse command value is set to 0. Therefore, when the current flows through the exciting coil, the maximum negative voltage is Since the voltage is not applied to the exciting coil when the current is applied to the exciting coil and no current is flowing, the current of the exciting coil can quickly follow the current command value.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a reluctance motor control device according to the present invention will be described below. Figure 2
FIG. 1 is a block diagram showing an overall 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 is
Torque command value T given from outside ^*So that
Rotation angle detection for detecting the rotation angle θ of the reluctance motor 5
Motor rotation output from the rotation angle sensor 6 as means
Each phase using the angle θ (a phase, b phase, c phase in this embodiment)
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^*The voltage command value calculation circuit 2 for calculating
Pressure command value Va^*, Vb^*, Vc^*Voltage equivalent to
PWM pulse command to apply the pulse to the exciting 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 for each phase of reluctance motor 5
Power conversion circuit 4 as a drive means for energizing
It is equipped with.

Next, the voltage command value calculation circuit 2 of this embodiment
Will be described. First, the relationship between the voltage and current of the reluctance motor will be described before describing the circuit configuration. The relationship between the current and 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 value In equations (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 current command values for the a, b, and c phases of the reluctance motor are ia ^* , ib ^* , ic ^* , and the voltage command values are Va ^* , V, respectively.
Assuming b ^* and Vc ^* , the current command value and the voltage command value are
It can be obtained by the following equations (11) to (13).

[0022]     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 this embodiment in detail.
FIG. In FIG. 3, the voltage command value calculation circuit 2
Is the voltage command value Va for phase a, phase b, and phase c ^*, Vb^*, Vc
 ^*Figures 2A, 2B and 2C for computing
As shown in 1 (a), each phase's
Data of own inductances La, Lb, Lc are stored.
And a table map 2-1. In addition, each performance
The arithmetic units 2A, 2B and 2C have the same configuration.
Then, only the a-phase arithmetic unit 2A will be described below.

The calculator 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 the rotation angle sensor 6. 2-2, the magnetic flux command value .phi.a ^* from the magnetic flux target response Faima ^* and its time differential value d (φma ^*) / d
The filter 2-3 for obtaining t, the circuit 2-4 for obtaining the voltage command value R · ia ^* of the resistance by multiplying the current command value ia ^* by the resistance value R of the exciting coil, and the time of the target response φma ^* of the magnetic flux. An adder 2-5 for obtaining the sum of the differential value d (φma ^* ) / dt and the resistance component voltage command value R · ia ^* is provided, and the calculation result of the adder 2-5 is the voltage for the a-phase exciting coil. It is configured to output as the command value Va ^* .

Further, FIG. 4 shows the power conversion circuit 4 of this embodiment.
Shows the configuration of. In FIG. 4, when the PWM pulse command value for each phase from the PWM pulse command value creating 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, and the phase 2 Switching elements (MOSFET etc.) 19 and 20, 2
By driving 1 and 22, 23 and 24, the values of the currents flowing through the exciting coils 13, 14, and 15 of the respective phases are adjusted to match the current command values. In FIG. 4, 12 is a power source, 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 ^* , ic ^* calculated by the current command value calculation circuit 1 according to the motor rotation angle θ are used as the motors of the respective phases. In order to make the current follow, it is necessary to calculate the voltage command values Va ^* , Vb ^* , Vc ^* shown in the equations (11) to (13). Therefore, in the voltage command value arithmetic circuit 2, each arithmetic unit 2A
2C, the current command values ia ^* , ib ^* , and ic ^* respectively input from the current command value calculation circuit 1 and the inductance data table map 2-1 corresponding to the detected motor rotation angle θ are searched. Based on the inductances La, Lb, Lc of each phase, the magnetic flux command values φa ^* , φ of each phase
b ^*, seek φc ^*, the magnetic flux command value φa ^*, φb ^*,
.phi.c ^* of target response φma ^*, φmb ^*, time-differentiated value d for ^{φmc * (φma *) / dt} , d (φmb *) / dt, d
(Φmc ^* ) / dt is obtained, and this is given by equations (11) to (13).
It is the voltage command value for the inductance component at. Also,
The voltage command values Ria ^* , Rib ^* , Ric ^{* for} resistance are
It is calculated from the product of the current command values ia ^* , ib ^* , ic ^* and the resistance value R. Then, the adder 2-5 calculates the sum of these to generate the voltage command values Va ^* , Vb ^* , Vc ^* to be applied to the exciting coils 13 to 15 of the respective phases.

Here, if ωc in each of the filters of the arithmetic units 2A to 2C is increased, the target responses φma ^* and φ of the magnetic flux are obtained ^.
mb ^* , φmc ^* time derivative d (φma ^* ) / dt, d (φmb
^* ) / Dt and d (φmc ^* ) / dt approach the time derivative of the magnetic flux command value. Therefore, if .omega.c is increased within the range of the required current responsiveness, 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 to PWM pulse command value Vsa^*, Vsb^*, V
sc^*And the created PWM pulse command value Vsa^*,
Vsb ^*, Vsc^*Drive circuit 1 of power conversion circuit 4 based on
Generates PWM pulse signal from 1 and exciting coil for each phase
Power is supplied to 13 to 15. Due to this configuration
For example, without providing a current sensor, the excitation coil for each phase
Current can be controlled and output even when current is applied to multiple phases simultaneously
The torque can be controlled accurately.

Originally, the relationship between voltage and current is expressed by the equation (5).
It is expressed by a complicated expression like (7). Therefore, if a mutual inductance data map is provided in addition to the self-inductance table map 2-1 by the same method as this embodiment, a reluctance motor control system based on equations (5) to (7) is configured. You can also do it. Next, a second embodiment will be described.

The overall structure of the second embodiment is similar to that of the first embodiment shown in FIG. The second embodiment differs from the first embodiment in a table map that stores 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 designated by the same reference numerals and the description thereof will be omitted. Figure 5
In the table map 2-1 ′ storing the inductance data of the present embodiment, the self-inductance data is searched based on the motor rotation angle θ and the current command values ia ^* , ib ^* , ic ^* .

When the current of the exciting coils 13 to 15 becomes large, saturation of magnetic flux occurs. In such a saturation region, the self-inductances La, Lb, and Lc change not only by the motor rotation angle θ but also by 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 exciting coil 13 of each phase
If the data of the self-inductances La, Lb, and Lc of 15 are retrieved, the current command values ia ^* , ib ^* , and ic ^* 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 similar to that of the first embodiment shown in FIG. In the third embodiment, the PWM pulse command value creating circuit is different, and the operation of the PWM pulse command value creating circuit of the present embodiment will be described with reference to the flowchart of FIG. In addition, although the a phase will be described below, the same applies to other b phases and c phases.

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), the voltage command value Va ^* is read. Next, the voltage command value Va ^*
A map in which the duty of the PWM pulse command value Vsa ^* is stored is referred to (step (5)). This map contains the duty of the PWM pulse command value that matches the voltage command value Va ^* with the equivalent voltage applied to the a-phase exciting coil 13, and is applied to the voltage command value and the exciting coil. The deviation of the equivalent voltage can be corrected.

Now, the duty data stored in the map will be described in detail. FIG. 7 shows the PWM command signal Vsa
It is the figure which showed the relationship of the a phase excitation coil applied voltage Va with respect to ^* . When current is flowing in 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 given by equations (14) and (15).

[0034] However, due to the response speed of the switching elements 19 and 20, the rise and fall responses are delayed as shown in FIG. 7, and the duty of the PWM pulse command value Vsa ^* differs from the actual exciting coil applied voltage Va. Therefore, the equivalent voltage applied to the exciting coil and outputs a voltage command value Va ^* PWM pulse command value corresponding to Vsa ^* directly put away <br/> become different. Therefore, in the present embodiment, in consideration of the response characteristics of the rising and falling edges of the switching element, when there is a deviation as shown in FIG. 7, for example, the PWM pulse command value Vsa ^* is different from the voltage command value Va ^* . The duty data is created and mapped by devising the duty to be small. By doing so, the deviation between the voltage command value and the equivalent voltage applied to the exciting coil due to the response characteristics of the switching element can be corrected.

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)). In this way, if the duty of the PWM pulse command value is set to 0, when the current is flowing, equation (15)
Is applied to the exciting coil and the current decays fastest. When the current becomes 0, the voltage applied to the exciting coil becomes 0. Therefore, the current followability is good, and unnecessary switching can be eliminated.

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

[Brief description of 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 the PWM pulse command value creation circuit according to the 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

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-196095 (JP, A) JP-A-9-201100 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 7/05

Claims (6)

(57) [Claims] 1. A rotation angle detecting means for detecting a motor rotation angle, and a current command value for an exciting coil of each phase is calculated so as to output a torque according to a command value according to the detected motor rotation angle. Current command value calculating means, a voltage command value calculating means for calculating a voltage command value for the exciting coil of each phase from the calculated current command value and the detected motor rotation angle and motor parameter, and the calculated voltage PWM pulse command value creating means for creating a PWM pulse command value based on the command value, and driving means for generating a PWM pulse signal according to the created PWM pulse command value and energizing the exciting coil of each phase, A reluctance motor control device comprising: 2. The voltage command value calculating means calculates the inductance of the exciting coil of each phase according to at least the motor rotation angle, and the calculated inductance value and the current command value calculating means. A magnetic flux command value calculation means for calculating the magnetic flux command value of the exciting coil of each phase from the current command value, and a magnetic flux command value change amount calculation means for calculating the target response of the magnetic flux and its time change amount from this magnetic flux command value, An adding unit that calculates 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 time change amount of the calculated target response of the magnetic flux. The reluctance motor controller according to claim 1. 3. The inductance calculating means calculates the self-inductance of the exciting coil, and the magnetic flux command value calculating means calculates the magnetic flux command value from the self-inductance of the exciting coil and the current command value. Claim 2
The reluctance motor control device described. 4. The reluctance motor control device according to claim 2, wherein the inductance calculation step calculates the inductance according to a motor rotation angle and a current command value. 5. The PWM pulse command value creating means ensures that the voltage command value and the applied voltage are equal from the relationship between the PWM pulse signal generated from the driving means and the applied voltage applied to the exciting coil. The reluctance motor controller according to any one of claims 1 to 4, wherein the PWM pulse command value is created. 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.
5. The reluctance motor controller according to any one of 5 above.