JP7220074B2 - MOTOR CONTROL DEVICE AND MOTOR CONTROL METHOD - Google Patents

Description

The present invention relates to a motor control device and a motor control method.

As a method of controlling a permanent magnet type synchronous motor, there is a method of controlling the motor by a voltage command based on a speed command value. FIG. 4 is a block diagram showing a configuration example of a conventional motor control device. As shown in FIG. 4, the motor control device 901 includes a speed command unit 902, a voltage command unit 903, a two-to-three-phase conversion unit 904, an inverter 905, a three-to-two phase conversion unit 906, an integrator 907, a current sensor 908, It has a gain circuit 909 and a power factor angle calculator 910 . The motor controller 901 is also connected to a motor 920, which is a three-phase motor. Note that the motor control device 901 converts the three-phase current into a two-phase current using, for example, the Clarke transform, and further transforms the current into rotating coordinates using the Park transform.

The motor control device 901 controls the rotation of the motor 920 based on the three-phase current (iu, iv, iw) flowing through the motor 920 detected by the current sensor 908 . Since the current sensor 908 is provided for each phase, it has three current sensors.
Note that the voltage command unit 903 converts each of the three-phase (u, v, w) currents calculated from the output voltage of the inverter 905 from the three-phase to the two-phase conversion, the δ-axis current iδ, the inverter output frequency ωI, the proportional A δ-axis voltage command value V ^* δ and a γ-axis voltage command value V ^* γ are obtained by calculation using a constant K, a d-axis induced voltage coefficient Λd, and a proportional gain K (see, for example, Patent Document 1).

Further, when controlling a three-phase motor, there is also a method of detecting and controlling a two-phase current among the currents supplied to the motor. In this case, control is performed using two current sensors.

Japanese Patent No. 4764124

However, in the prior art, three or two current sensors were required to detect the three-phase current flowing through the motor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor control device and a motor control method capable of controlling a motor with a simpler configuration than the conventional one.

In order to achieve the above object, a motor control device (1) according to one aspect of the present invention provides one motor current (iu, iv, iw) flowing in each phase (u, v, w) of a three-phase AC motor. A current sensor (107) for detecting a motor current value (i) of a phase, and calculating an average value of at least one cycle of the motor current value of one phase detected by the current sensor, and calculating the average value of the one cycle by 3 and the rotor position (θ), a one-phase to two-phase conversion unit (108) for converting the one-phase motor current value into a two-phase current value by coordinate conversion, and the one-phase a voltage command unit (102) for generating two-phase voltage command values (V ^* δ, V ^* γ) using the two-phase current values converted by the two-phase conversion unit; and the two-phase voltage command values. are coordinate-converted into three-phase voltage command values (V ^* u, V ^* v, V ^* w), and the three-phase AC motor is driven based on the three-phase voltage command values. and conversion units (105, 106).
According to such a configuration, the one-phase to two-phase converter converts the current value of one phase into the current value of two phases, so that the motor current value can be detected by one current sensor. Thus, with such a configuration, the motor can be controlled with a simpler configuration than the conventional one.

Further, in the motor control device according to the aspect of the present invention, T is one cycle of the motor current, and the one-phase to two-phase conversion unit converts the one-phase motor current value (i) acquired by the current sensor to Calculate the exciting current component iδ using the rotor position (θ) and the following equation,

The torque current component iγ may be calculated using the one-phase motor current value (i) and the rotor position (θ) obtained by the current sensor and the following equation.

According to such a configuration, since there is no division and the processing time is relatively short, the motor can be controlled with a simpler configuration than the conventional one.

Further, in the motor control device according to the aspect of the present invention, in a first cycle and a second cycle following the first cycle, the voltage command unit The one-phase motor current value is integrated during the period of one cycle and converted into the two-phase current value, and the two-phase current converted during the first one-cycle period during the second one-cycle period. You may make it generate|occur|produce a voltage command value using a value.
According to such a configuration, the configuration can be configured simply, and the amount of calculation can be reduced.

Further, in the motor control device according to an aspect of the present invention, the one-phase to two-phase conversion unit converts the one-phase motor current value into a two-phase current value at each time interval shorter than one cycle. may
According to such a configuration, it is possible to perform motor control with quick response.

Further, the motor control device according to an aspect of the present invention includes a power factor angle determination unit (110 ), and a power factor angle adder/subtractor (109, 104) for adding the power factor angle to the rotation angle used when converting the two-phase voltage command value into the three-phase voltage command value, The two-to-three-phase conversion unit coordinate-converts the two-phase voltage command values into the three-phase voltage command values based on an angle obtained by adding the power factor angle to the rotation angle. good too.
With such a configuration, it is possible to reduce the current value required to generate torque.

In order to achieve the above object, a motor control method according to one aspect of the present invention provides current detection in which a current sensor detects a motor current value (i) of one phase among motor currents flowing in each phase of a three-phase AC motor. a step in which the one-phase to two-phase converter calculates an average value of at least one cycle of the one-phase motor current value detected by the current detection procedure, and multiplies the average value of the one cycle by 3; , a rotor position (θ), and a one-phase to two-phase conversion procedure for converting the one-phase motor current value into a two-phase current value by coordinate conversion; a voltage command procedure for generating a two-phase voltage command value using the two-phase current values converted by the procedure; and a two-to-three-phase conversion procedure for converting the three-phase voltage command values to drive the three-phase AC motor based on the three-phase voltage command values.

According to the present invention, the motor can be controlled with a simpler configuration than the conventional one.

1 is a block diagram showing a configuration example of a motor control device according to an embodiment; FIG. It is a figure which shows the 1st calculation procedure which the 1 phase 2 phase conversion part which concerns on this embodiment performs. It is a figure which shows the 2nd calculation procedure which the 1 phase 2 phase conversion part which concerns on this embodiment performs. 1 is a block diagram showing a configuration example of a conventional motor control device; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration example of a motor control device 1 according to this embodiment. As shown in FIG. 1, the motor control device 1 includes a subtractor 101, a voltage command section 102, an integrator 103, an adder 104 (power factor angle adder/subtractor), a two-to-three phase converter 105, An inverter circuit 106 (two-phase three-phase converter), a current sensor 107, a one-phase to two-phase converter 108, a gain circuit 109 (power factor angle adjuster), and a power factor angle determiner 110 are provided. The motor control device 1 is also connected to a motor 10 (three-phase AC motor) which is a three-phase motor. Note that in the configuration shown in FIG. 1, the inverter circuit 106 also includes a PWM circuit. Note that FIG. 1 shows an example in which the current sensor 107 detects the motor current iu among the three-phase motor currents (iu, iv, iw).

In the following description, _ωm is the rotation speed command, n is the number of pole pairs of the motor, ωI is the inverter output frequency (primary frequency), V ^* δ is the δ-axis voltage command value, and V ^* γ is the γ-axis voltage command value. V ^* u is a u-phase voltage command value, V ^* v is a v-phase voltage command value, V ^* w is a w-phase voltage command value, Vu is a u-phase output voltage, Vv is the v-phase output voltage, Vw is the w-phase output voltage, iu is the u-phase motor current, iv is the v-phase motor current, and iw is the w-phase motor current. iδ is the excitation current component, iγ is the torque current component, θ is the rotation axis (rotor position) of the three-phase two-phase conversion, and φ is the power factor angle.

A speed command value (nω _m ^* ) is input to the motor control device 1 from, for example, a control device (not shown). The motor control device 1 controls rotation of the motor 10 based on the inputted speed control value.

The subtractor 101 subtracts the value obtained by multiplying the torque current component iγ output by the gain circuit 109 by the gain _Kω from the speed command value (nω _m ^* ), and the value after the subtraction is used as the inverter output frequency ωI to obtain the voltage. It outputs to command section 102 and integrator 103 . Note that the speed command value is obtained by multiplying the rotational speed command _ωm by the pole logarithm.

The voltage command unit 102 uses the inverter output frequency ωI output by the subtractor 101 and the excitation current component iδ output by the one-phase to two-phase conversion unit 108 to obtain the δ-axis voltage command value V ^* δ of the rotating rectangular coordinate system and γ-axis voltage command value V ^* γ is generated. Voltage command unit 102 outputs the generated δ-axis voltage command value V ^* δ and γ-axis voltage command value V ^* γ to two-to-three phase conversion unit 105 .

The integrator 103 integrates the inverter output frequency ωI output from the subtractor 101 to calculate the rotor position θ. The integrator 103 outputs the calculated output voltage phase θ to the adder 104 and the one-phase to two-phase converter 108 .

The adder 104 adds the power factor angle φ to the rotor position θ output from the integrator 103 , and outputs the added θ+φ to the two-to-three-phase converter 105 .

In the two-to-three-phase conversion unit 105, the adder 104 outputs the two-phase voltage deviation values (the δ-axis voltage command value V ^* δ and the γ-axis voltage command value V ^* γ) output by the voltage command unit 102. θ+φ is used to convert to three-phase voltage command values (u-phase voltage command value V ^* u, v-phase voltage command value V ^* v, and w-phase voltage command value V ^* w). As in Patent Document 1, the two-to-three-phase converter 105 detects step-out when the δ-axis current iδ continues to be equal to or greater than a specified value for a predetermined period of time.

The inverter circuit 106 converts the three-phase voltage command values (the u-phase voltage command value V ^* u, the v-phase voltage command value V ^* v, and the w-phase voltage command value V ^* w), three-phase output voltages (u-phase output voltage Vu, v-phase output voltage Vv, and w-phase output voltage Vw) are generated. The inverter circuit 106 supplies the generated three-phase output voltage to the motor 10 .

The current sensor 107 detects a motor current value of one phase among the motor currents (iu, iv, iw) flowing through the motor 10 and outputs the detected motor current value to the one-phase to two-phase converter 108 . N If one of the motor currents (iu, iv, iw) is not specified, it will be referred to as motor current i. It should be noted that the current sensor 107 is preferably a Hall sensor or a shunt resistor capable of detecting direct current.

The one-phase to two-phase conversion unit 108 stores conversion formulas. A one-phase to two-phase conversion unit 108 calculates an excitation current component iδ from the motor current value output by the current sensor 107 using a conversion formula, and calculates a torque current component iγ. One-phase to two-phase conversion section 108 outputs exciting current component i δ to voltage command section 102 . Further, the one-phase to two-phase conversion unit 108 outputs the torque current component iγ to the gain circuit 109 and the power factor angle determination unit 110 . Note that the conversion formulas stored in the one-phase to two-phase conversion unit 108 will be described later. Further, as will be described later, when a motor current value is obtained for each period shorter than one cycle and calculation is performed, the one-phase to two-phase conversion unit 108 includes a storage unit that stores the obtained motor current value.

The gain circuit 109 multiplies the torque current component iγ output from the one-phase to two-phase converter 108 by the gain _Kω and outputs the result to the subtractor 101 .

Power factor angle determination unit 110 calculates a power factor angle φ of torque current component iγ output from one-phase to two-phase conversion unit 108 and outputs the calculated power factor angle φ to adder 104 .

Next, a method of calculating the δ-axis voltage command value V ^* δ and the γ-axis voltage command value V ^* γ will be described.
Voltage command unit 102 calculates δ-axis voltage command value V ^* δ using inverter output frequency ωI, excitation current component iδ, and the following equation (1).

Also, the voltage command unit 102 obtains the γ-axis voltage command value V ^* γ using the inverter output frequency ωI, the excitation current component iδ, and the following equation (2).

In equation (1), K _δ is the δ-axis proportionality constant, Λd is the d-axis induced voltage coefficient, and K is the proportionality constant.

Next, conversion performed by the one-phase to two-phase conversion unit 108 will be described.
First, the case where the current detected by the current sensor 107 is the u-phase motor current value iu will be described.
In this case, the one-phase to two-phase converter 108 calculates the excitation current component iδ using the following equation (3), and calculates the torque current component iγ using the following equation (4). Note that T is one cycle of the motor current, which is 2π.

Here, using equations (3) and (4), the grounds for obtaining the excitation current component iδ and the torque current component iγ from the current value of one phase will be described.
In the prior art (Patent Document 1), in the three-phase to two-phase conversion, the three-phase current values (iu, iv, iw) are converted into two-phase current values (iδ, iγ) using the following equation (5), for example. do.

In equation (5), A is a coefficient. In equation (5), the current values iu, iv, and iw are only 2π/3 apart from each other, and when integrated over a period of 0 to 2π, which is one cycle, the three-phase current values (iu, iv, iw) have the same value. Therefore, the value obtained by integrating one of the three-phase current values (iu, iv, iw) over a period of 0 to 2π is multiplied by 3 to correspond to the three-phase current value ( iu, iv, iw) minutes. Also, in equations (3) and (4), by averaging one cycle, even if there are distortion components in the current value, these components can be averaged. can be reduced.

Next, a case where the current detected by the current sensor 107 is the v-phase motor current value iv will be described.
In this case, the one-phase to two-phase converter 108 calculates the excitation current component iδ using the following equation (6), and calculates the torque current component iγ using the following equation (7).

Next, a case where the current detected by the current sensor 107 is the w-phase motor current value iw will be described.
In this case, the one-phase to two-phase converter 108 calculates the excitation current component iδ using the following equation (8), and calculates the torque current component iγ using the following equation (9).

Thus, the one-phase to two-phase converter 108 integrates the motor current value detected by the current sensor 107 for one period (T) and multiplies the average value by 3 to obtain the exciting current component iδ and the torque current component iγ. calculate.
Thus, according to this embodiment, the motor 10 can be controlled using the motor current value detected by one current sensor 107 . As a result, in this embodiment, one current sensor 107 can be used to control the rotation of the motor.
As described above, in the present embodiment, since the excitation current component iδ and the torque current component iγ are calculated using the equations (3), (4), (6) to (9), there is no division and the processing time is relatively short. short. If there is a division and the operation takes a long time, it is necessary to occasionally stop the phase difference detection process or perform the process in the main loop as a countermeasure against the long operation time of the division.

As described using equations (3), (4), (6) to (9), the calculation of the one-phase to two-phase converter 108 takes one cycle (T). Therefore, the control of the motor control device 1 is delayed by one cycle. Here, when an air conditioner motor or the like is to be controlled, there is no problem even if the control is delayed by one cycle. This embodiment is suitable for, for example, an inverter for air conditioner motor control in which the rotational speed of the motor 10 changes slowly.

In addition, in equations (3), (4), (6) to (9), an example of integrating for one cycle has been described, but the present invention is not limited to this. Depending on the application, the period of integration may be two periods (2T) or more. Also, if there is no offset in the current value during the integration period and positive and negative values are ensured, the integration period may be, for example, a half cycle (π).

Here, the operation of the motor control device 1 will be described.
First, the control when the voltage command unit 102 is set to the formulas (1) and (2) will be described. Here, in order to facilitate understanding, a case where the power factor angle φ(i) is 0 will be described. Since φ is the power factor angle, the power factor represented by cos φ is 1 when the phase difference between the voltage applied to the motor 10 and its current is 0. Therefore, this control is so-called unity power factor control.

In the calculations performed by the voltage command unit 102 based on equations (1) and (2), for example, if the γ-axis voltage command value V ^* γ is smaller than the terminal voltage of the motor 10, the excitation current component iδ is negative to weaken the magnetic field. become. Conversely, if the γ-axis voltage command value V ^* γ is large, the magnetic field is strengthened accordingly, and the excitation current component iδ becomes positive.
In the calculation of equation (1), the δ-axis voltage command value performs negative proportional control so that the exciting current component iδ becomes zero. Thus, if there is positive or negative fluctuation in the excitation current component i.delta., the .delta.-axis voltage command value V ^* .delta. is determined so that the fluctuation in the excitation current component i.delta.

The γ-axis voltage command value V ^* γ is set to a voltage value that compensates for the voltage ΛdωI, which corresponds to the induced voltage. Integral control is performed. That is, in the calculation of equation (2), if the excitation current component i δ accumulates in either positive or negative value, a voltage value is determined that returns to the original value with a correspondingly larger value.

By controlling in this manner, the excitation current component iδ becomes 0, and when the excitation current component iδ becomes 0, the δ-axis voltage command value V ^* δ also becomes 0. As a result, the current flowing through the motor 10 and the voltage applied to the motor have only the γ-axis component and are in phase with each other, resulting in a power factor of 1. As a result, the product of voltage and current is minimized, and power-saving control is possible (see Patent Document 1).

Furthermore, as described in Patent Document 1, the control of the minimum current required to generate torque can be realized by actively controlling the power factor angle (phase difference) instead of the power factor angle φ=0. . For this reason, in this embodiment, the power factor angle adjusting means (adder 104, power factor angle A decision unit 110) is provided. Since the rotation axis φ is a function of the current I, I is first obtained using the torque current component iγ fed back as shown in FIG. Once I is obtained, it is multiplied by a constant to obtain φ. Further, the adder 104 adds φ to θ.

Further, in this embodiment, as described above, the excitation current component iδ and the torque A current component iγ is calculated. The torque current ^{component iγ thus calculated is multiplied by the gain Kω and negatively fed back to the speed command value nωm*} _{, which} ^is _the frequency. Fixed.

The implication of this control is that when the load on the motor 10 becomes heavy and the position of the rotor (not shown) of the motor 10 lags behind the rotating magnetic field, the current increases. Since the current decreases as it advances against the rotating magnetic field, it is stabilized by correcting the speed command value.
Further, in the present embodiment, the voltage command unit 102 performs control so that Vδ=Iδ=0 based on the above equations (1) and (2). If the phases used for two-phase to three-phase conversion are different, the difference φ is controlled to be the power factor angle.

Next, the calculation method of the one-phase to two-phase conversion unit 108 will be described.
First, the first calculation method will be explained.
FIG. 2 is a diagram showing a first calculation procedure performed by the one-phase to two-phase conversion unit 108 according to this embodiment. In FIG. 2, the vertical axis is the current value and the horizontal axis is the time. A waveform g1 is the waveform of the motor current i. One period (T) is from time t1 to t2.

When performing control for each cycle as shown in FIG. 2, the amount of calculation can be reduced compared to the control for each calculation step explained using FIG. be. Therefore, when the control is performed for each cycle as shown in FIG. 2, both the configuration and the calculation can be made simpler.

(Step S1) During the period from time t1 to t2, the one-phase to two-phase converter 108 integrates the motor current i (sin(i) or cos(i)).
(Step S2) During the period from time t2 to t3, the one-phase to two-phase converter 108 uses the above-described equations (3), (4), (6) to (9) to calculate the excitation current component iδ and the torque current component iγ Calculate

Thus, in the control shown in FIG. 2, the voltage command unit 102 integrates the single-phase motor current value during the period of the first cycle (time t1 to t2) and converts it into a two-phase current value. Then, the voltage command value is generated using the two-phase current values converted in the period of the first period during the period of the second period (period of time t2 to t3).

Next, the second calculation method will be explained.
FIG. 3 is a diagram showing a second calculation procedure performed by the one-phase to two-phase conversion unit 108 according to this embodiment.
In FIG. 3, the vertical axis is the current value and the horizontal axis is the time. A waveform g2 is the waveform of the motor current i. One period (T) is from time t11 to t14. Furthermore, Δt during the period from time t11 to t12 is a calculation step.

(Step S11) The one-phase to two-phase conversion unit 108 acquires a motor current value every Δt (time t1, t2, t3, . . . ) and stores the acquired motor current value.
(Step S12) At time t14, the one-phase to two-phase converter 108 uses the above-described equations (3), (4), and (6) to (9) to calculate the excitation current component iδ during the period from time t11 to t14. and the torque current component iγ.
(Step S13) At time t15, the one-phase to two-phase converter 108 uses the above-described equations (3), (4), and (6) to (9) to calculate the excitation current component iδ during the period from time t12 to t15. and the torque current component iγ.
(Step S14) At time t16, the one-phase to two-phase converter 108 uses the above-described equations (3), (4), and (6) to (9) to calculate the excitation current component iδ during the period from time t13 to t16. and the torque current component iγ.

If processing is performed for each calculation step as shown in FIG. 3, a storage unit for storing the current value for each step time is required, but as shown in FIG. can. As a result, by performing control using the calculation steps shown in FIG. 3, it is possible to accurately control the transient response of the motor 10 as well.

A program for realizing all or part of the functions of the motor control device 1 of the present invention is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by a computer system, All or part of the processing performed by the motor control device 1 may be performed by executing it. It should be noted that the "computer system" referred to here includes hardware such as an OS and peripheral devices. Also, the "computer system" includes a WWW system provided with a home page providing environment (or display environment). The term "computer-readable recording medium" refers to portable media such as flexible discs, magneto-optical discs, ROMs and CD-ROMs, and storage devices such as hard discs incorporated in computer systems. In addition, "computer-readable recording medium" means a volatile memory (RAM) inside a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. , includes those that hold the program for a certain period of time.

Further, the above program may be transmitted from a computer system storing this program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in a transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Further, the program may be for realizing part of the functions described above. Further, it may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

As described above, the mode for carrying out the present invention has been described using the embodiments, but the present invention is not limited to such embodiments at all, and various modifications and replacements can be made without departing from the scope of the present invention. can be added.

1... Motor control device,
101... Subtractor,
102... Voltage command part,
103...Integrator,
104 Adder,
105 ... two-phase three-phase conversion unit,
106... Inverter circuit,
107 ... current sensor,
108 ... one-phase two-phase conversion unit,
109... gain circuit,
110... Power factor angle determination unit,
10... Motor

Claims (6)

a current sensor for detecting a motor current value (i) of one phase among the motor currents flowing in each phase of the three-phase AC motor;
An average value of at least one cycle of the motor current value of one phase detected by the current sensor is calculated, and the one-cycle average value is multiplied by 3 and the rotor position (θ) is used to calculate the one-phase a one-phase to two-phase conversion unit that coordinates-converts phase motor current values into two-phase current values;
a voltage command unit that generates a two-phase voltage command value using the two-phase current values converted by the one-phase to two-phase conversion unit;
a two-phase to three-phase conversion unit that coordinates-transforms the two-phase voltage command values into three-phase voltage command values, and drives the three-phase AC motor based on the three-phase voltage command values;
A motor controller comprising: T is one cycle of the motor current,
The one-phase to two-phase converter calculates an exciting current component iδ using the one-phase motor current value (i) and the rotor position (θ) obtained by the current sensor and the following equation,

calculating a torque current component iγ using the one-phase motor current value (i) and the rotor position (θ) obtained by the current sensor and the following equation;

The motor control device according to claim 1. A first cycle and a second cycle following the first cycle,
The voltage command unit integrates the one-phase motor current value during the first period of one cycle to convert it into the two-phase current value, and integrates the first one-phase motor current value during the second period of one cycle. generating a voltage command value using the two-phase current values converted in the period of the cycle;
The motor control device according to claim 1 or 2. The one-phase to two-phase conversion unit converts the one-phase motor current value into a two-phase current value at each time interval shorter than the one cycle,
The motor control device according to claim 1 or 2. a power factor angle determination unit that determines a power factor angle from one of the two-phase current values converted by the one-phase to two-phase conversion unit;
a power factor angle addition/subtraction unit for adding the power factor angle to the rotation angle used when converting the two-phase voltage command value into the three-phase voltage command value;
with
The two-to-three-phase conversion unit coordinate-converts the two-phase voltage command values into the three-phase voltage command values based on an angle obtained by adding the power factor angle to the rotation angle.
The motor control device according to any one of claims 1 to 4. a current detection procedure in which a current sensor detects a motor current value (i) of one phase among the motor currents flowing in each phase of the three-phase AC motor;
A one-phase to two-phase conversion unit calculates an average value of at least one cycle of the motor current values of one phase detected by the current detection procedure, and multiplies the average value of the one cycle by 3, and the rotor position. a one-phase to two-phase conversion procedure for coordinate-converting the one-phase motor current value into a two-phase current value based on (θ);
a voltage command procedure in which a voltage command unit generates a two-phase voltage command value using the two-phase current values converted by the one-phase to two-phase conversion procedure;
A two-phase to three-phase converter converts the two-phase voltage command values into three-phase voltage command values by coordinate conversion, and drives the three-phase AC motor based on the three-phase voltage command values. a three-phase conversion procedure;
motor control method including;

Images