KR100503441B1 - Apparatus for detecting position of rotor in switched reluctance motor and method of the same - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting a rotor position of a switched reluctance motor. The present invention relates to detecting a rotor position of a switched reluctance motor having a stator and a rotor and a search coil wound around each phase of the stator pole. The reference data on the organic electromotive force of the search coil for each angle of the rotor is generated, and when a driving command is input, a control signal for applying a single pulse voltage to the motor is generated. Detects, calculates an Euclidean square distance between the detected organic electromotive force value and the reference value for each angle of the reference data stored in the storage unit, and calculates a reference value having a shortest Euclidean square distance from the detected organic electromotive force value. By estimating the initial position of the rotor and outputting the result value according to the estimated position data Achieved.

According to the present invention, it is possible to detect the position of the rotor in the stationary state by the search coil, and to provide a separate sensor for detecting the position of the rotor or to forcibly fix the position of the rotor to the specific position during the stop. Even with the search coil alone, the switched reluctance motor can be driven while detecting the position of the rotor.

Description

Apparatus for detecting position of rotor in switched reluctance motor and method of the same}

The present invention relates to an apparatus and method for detecting a rotor position of a switched reluctance motor, and more particularly, to an apparatus and method for detecting a rotor position of a switched reluctance motor capable of detecting an initial position of a rotor in a stationary state using only a search coil. It is about.

In general, a motor includes a DC motor that operates by receiving a direct current and an AC motor that operates by receiving an alternating current. While the DC motor is easy to control the speed and torque, the structure is complicated and the durability is bad, while the AC motor has a simple structure and good durability, while the initial starting and speed control are difficult.

In recent years, the advantages of the above-described DC motor and AC motor can be collected and the disadvantages can be minimized. Inverter-type motors capable of efficient speed control have been in the spotlight.

The inverter-type motor employs an inverter that converts a direct current into an alternating current having a phase difference for each phase and applies it to each phase of the motor. The inverter applies power to each phase of the motor according to a predetermined phase difference. It is composed of a plurality of switching elements for operating by a pulse width modulation signal (Pulse Width Modulation Signal) applied from the control means.

A representative of such inverter type motors is a switched reluctance motor ("SRM"). The switched reluctance motor has a double salient pole structure in which the salient poles are formed on the rotor and the stator, respectively. It is most widely used due to many advantages such as system controllability, robustness, environmental resistance and high speed operation.

Such a switched reluctance motor requires a position sensor of a rotor such as a resolver, an encoder, a photo interrupter, a hall sensor, or the like for control.

However, the rotor position sensor is relatively expensive, increases the cost, is vulnerable to shock, low reliability in a high temperature and high pressure environment, such as a compressor, increase the volume of the motor, and can detect the speed of the rotor There is a limitation in that it limits the high speed rotation of the motor.

Accordingly, various methods for improving the disadvantages of the rotor position sensor have been studied, and one of them is a technology for detecting the position of the rotor by mounting a search coil in a switched reluctance motor.

FIG. 1 is a schematic diagram of a switched reluctance motor equipped with a search coil. In the switched reluctance motor shown in the same diagram, protrusions are formed on the rotor 1 and the stator 2 so as to face each other, and the stator ( Coils 3a, 3b, and 3c on A, B, and C are wound around each yoke of 2).

In addition, three search coils 4ab, 4bc, and 4ca are wound around the pole portion of the stator 2, and each search coil is connected to two phase windings of the three-phase windings 3a, 3b, and 3c. It is arrange | positioned so that it may adjoin.

In the switched reluctance motor of this structure, when an electric current is applied from the inverter to the windings 3a, 3b, and 3c of the three phases, organic electromotive force is generated in the search coils 4ab, 4bc, and 4ca by electromagnetic induction. The electromotive force induced in the search coil includes the positional information of the rotor 1, and the position of the rotor 1 is detected by measuring the organic electromotive force.

The voltage of the organic electromotive force induced in the search coils 4ab, 4bc, and 4ca of each phase is determined by the time-varying chain flux caused by the current of the phase windings 3a, 3b, and 3c and the rotational motion of the rotor 1 according to Faraday's law. The waveform is represented by the sum of the time-varying linkage fluxes generated by the change of mutual inductance.

As described above, the waveform of the voltage induced in the search coils 4ab, 4bc, and 4ca, that is, the organic electromotive force, may be expressed by Equation 1 below.

Here, "λ _s " represents the linkage flux of the search coil, "i _p " is the sum of the currents of the phase windings, and "M" is the mutual inductance by the magnetic inductance of the phase windings and the magnetic inductance of the search coil.

In Equation 1 (2), the time-varying linkage flux caused by the change of the phase current is a transform emf component corresponding to the transformer component of the switched reluctance motor, and the change of mutual inductance by the rotation of the rotor 1 The time-varying linkage flux generated by is a velocity emf component.

That is, the electromotive force of the search coils 4ab, 4bc, and 4ca is induced by the principle of the transformer and the principle of the generator, and the electromotive force and frequency of the transformer component as in Equation 1 (2) and (3) described above. The sum of the velocity electromotive force of the electron 1 indicates that the position information of the rotor is included.

Therefore, the position of the rotor 1 can be detected by measuring the electromotive force of the search coils 4ab, 4bc, and 4ca.

However, since the motor is in the stopped state at the initial start of the motor, the electromotive force is not generated in the search coil, and thus there is a problem in that the rotor position at the stop cannot be estimated.

Since the switched reluctance motor can be driven only by knowing the initial position of the rotor, the conventional research has been performed by initializing the rotor to the desired position by the forced alignment method. Where it is not necessary to reverse rotation, it is a fatal problem, so it is difficult to apply it in practice.

Accordingly, the present invention has been made to solve the above problems, and provides an apparatus and method for detecting a rotor position of a switched reluctance motor capable of detecting a rotor position in a stationary state by a search coil. There is a purpose.

The apparatus for detecting a rotor position of a switched reluctance motor according to the present invention for achieving the above object includes a search coil for each phase wound around the pole of the stator in a switched reluctance motor including a stator and a rotor. A storage unit for storing reference data on the organic electromotive force of the search coil for each position of the former, and a control signal for applying a single pulse voltage to the motor when a driving command is input, and then the organic electromotive force for the search coil of each phase The Euclidean square distance between the detected organic electromotive force value and the reference value for each angle of the reference data stored in the storage unit is calculated, and the Euclidean square distance with the detected organic electromotive force value is shortest. By obtaining the reference value, the initial position of the rotor is estimated and the result value according to the estimated position data is output. Characterized in that by the control signal applied from the control means, the control means is configured to include a power supply means for driving a voltage is applied to the motor.

The rotor position detection method of the switched reluctance motor according to the present invention for achieving the above object, the rotor position of the switched reluctance motor is made of a stator and a rotor, the search coil is wound around each phase of the stator pole In the step of storing the reference data for the organic electromotive force of the search coil of each rotor position, the step of applying a single pulse voltage to the motor when a drive command for the motor is input, and by the single pulse voltage A step of measuring organic electromotive force for the search coil of each phase to be extracted, and comparing the measured organic electromotive force of the search coil with the stored reference data to estimate the initial position of the rotor through the reference data closest to the measured value. And outputting a result value according to the initial position data of the estimated rotor. Characterized in that made.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram of a rotor position detection device of a switched reluctance motor according to a preferred embodiment of the present invention, as can be seen with reference to the same figure, the rotor position detection device of a switched reluctance motor according to the present invention, The switch includes a switched reluctance motor (M), a control unit (10), a data table (20), an inverter (30), and an A / D conversion unit (40).

The switched reluctance motor (hereinafter, abbreviated as " motor ") M is provided with protrusions so that the rotor 1 and the stator 2 face each other, and each yoke portion of the stator 2 A winding (not shown) of each phase is wound.

Three search coils 4ab, 4bc, 4ca are wound around the protruding portion of the stator 2, and each search coil is disposed to be adjacent to two phase coils of the three phase coils.

The control unit 10 generates a pulse width modulated signal for applying a single pulse voltage to the motor M when a driving command is input, and then detects the induced electromotive force for the search coils 4ab, 4bc, and 4ca of the phases. By comparing the detected organic electromotive force with the reference data stored in the storage unit 20, the initial position of the rotor 1 is estimated using the reference data closest to the detected value, and the motor M is estimated according to the estimated position data. Outputs the pulse width modulated signal and the rotor position information for driving.

The data table 20 stores reference data on the organic electromotive force of the search coil for each position of the rotor and provides the reference data to the controller 10 in response to a request from the controller 10.

The inverter 30 is composed of a plurality of switching elements (for example, field effect transistors, etc.) for firing or extinguishing each phase winding of the motor M, and pulses according to a pulse width modulation signal applied from the controller 10. By the width modulation, the DC power DC input from the DC power supply is converted into AC power and applied to each phase winding of the motor M.

The A / D converter 40 converts the voltage waveform of electromotive force induced in the search coils 4ab, 4bc, and 4ca of each phase into digital data and inputs the digital waveform to the controller 10.

Now with reference to the accompanying drawings, the operation of the present invention configured as described above will be described.

According to the present invention, the electromotive force induced in the search coils 4ab, 4bc, and 4ca differs depending on the position of the rotor 1 while the motor M is stopped. According to the pre-processing step of generating and storing the reference data for the organic electromotive force of the search coil, and the position detection process of estimating the position of the rotor 1 by using the reference data.

The preprocessing process is to obtain a reference value Vs-θ _R that maps the relationship between the organic electromotive force Vs of the search coils 4ab, 4bc, and 4ca and the position θ _R of the rotor 1. It consists of the steps as shown in FIG.

For this pre-processing, a sensor for detecting the position of the rotor 1, a measuring device for measuring the organic electromotive force of each of the search coils 4ab, 4bc, and 4ca, and a power supply for applying a single pulse voltage to the motor M Each device is used, and the dual measuring device and the power supply may use the rotor position detection device of the switched reluctance motor shown in FIG. 2 as it is. That is, the control device 10 and the A / D conversion unit 40 is used as the measurement equipment, the inverter 30 may be used as the power supply device.

As the sensor for detecting the rotor position, a resolver, an encoder, a photo interrupter, a hall sensor, or the like may be used.

In FIG. 3, the experimenter moves the rotor 1 of the motor M in steps of a set angle (for example, about 1 °) and uses a power supply to generate a single pulse voltage of the set value at each angle of the motor M. FIG. The organic electromotive force of the search coils 4ab, 4bc, and 4ca is measured using the measuring equipment as well (S10).

Here, the single pulse voltage applied to the motor M is a very small chopping of the source voltage by the pulse width modulation of the power supply device, so that a short time interval such that continuous current cannot be established in three phases. Since each of the three phase windings is applied, the motor M continues to be stopped and only a fine current is applied to each phase winding.

The search coils 4ab, 4bc, and 4ca induce electromotive force, but the motor M is stopped, and thus includes only the electromotive force by the transformer component of the motor M, as shown in Equation 2 below. The electromotive force value induced in the search coils 4ab, 4bc, and 4ca of the upper phase depends on the position where the salient pole of the rotor 1 and the salient pole of the stator 2 face each other.

Here, "i _p " is the sum of the currents of the phase windings, and "M" is the mutual inductance by the magnetic inductance of the phase windings and the magnetic inductance of the search coil.

As described above, since the organic electromotive force generated by the search coils 4ab, 4bc, and 4ca includes the position information of the rotor 1 in the stationary state, the organic electromotive force of the search coils 4ab, 4bc, and 4ca is applied. The position of the rotor 1 can be estimated.

Therefore, the organic electromotive force of the search coils 4ab, 4bc, and 4ca measured for each angle of the rotor 1 through the experiment of the step S10 becomes a reference value for estimating the position of the rotor 1.

For reference, FIG. 4 is a graph measuring organic electromotive force of search coils for each phase when a single pulse voltage is input, and FIG. 5 is a graph showing distribution of organic electromotive force of search coils for each phase that varies according to the rotor position. .

5 is a waveform of electromotive force induced by the search coil 4ab, "Vsbc" is a waveform of electromotive force induced by the search coil 4bc, and "Vsca" is a waveform of electromotive force induced by the search coil 4ca. Waveform.

The organic electromotive force of FIGS. 4 and 5 is a digit value obtained through A / D conversion. When the rotor 1 is mechanically rotated from 0 ° to 90 °, the organic electromotive force is rotated from 0 ° to 360 °. In this case, the organic electromotive force value is acquired only from 0 ° to 90 ° in the experiment of the step S10.

The experimenter maps the relationship between the organic electromotive force (Vs) of the search coils (4ab, 4bc, 4ca) and the position (θ _R ) of the rotor 1 measured in the step S10 to obtain a Vs-θ _R reference value. This is stored in the data table 20 (S30).

Next, the position detection process is a process of detecting the position of the rotor 1 in the stationary state by using the Vs-θ _R reference value obtained by the above preprocessing process, the detailed steps of which are shown in FIG. same.

In FIG. 6, the controller 10 determines whether a motor drive command is input (S110), and when a motor drive command is input from an upper controller (not shown) or an operation unit (not shown), the motor M A pulse width modulated signal for applying a single pulse voltage for measurement is generated and output to the inverter 30.

In response to the pulse width modulation signal output from the controller 10, the inverter 30 pulse width modulates the DC power DC input from the DC power supply (not shown) to generate a single pulse voltage for measurement. Applies to (M) (S120).

In this case, the single pulse voltage applied to the motor M is the same as the single pulse voltage used in the above preprocessing, and is applied to the three-phase windings at a short time interval such that continuous current cannot be established in three phases. Therefore, the motor M continues to be stopped and only a fine current is applied to each phase winding.

Accordingly, electromotive force is induced in each of the search coils 4ab, 4bc, and 4ca, and electromotive force induced in each of the search coils 4ab, 4bc, and 4ca is converted into a digit value by the A / D converter 40 to control the controller 10. It is input to (S130).

The controller 10 determines the electromotive force induced in the search coils 4ab, 4bc, and 4ca by the digit value input from the A / D converter 40, and loads the Vs-θ _R reference value from the data table 20. (Load) (S140).

The controller 10 compares the organic electromotive force of the search coils 4ab, 4bc, and 4ca with the Vs-θ _R reference values loaded from the data table 20, and finds the nearest value from the Vs-θ _R reference values. The position of 1) is estimated (S160).

In this case, in step S160, an inference process of finding the nearest value from the Vs-θ _R reference values is required. In the present invention, as an example, the minimum error is determined using a squared Euclidean distance. Use the reasoning method

For reference, the Euclidean distance refers to the shortest straight line in multidimensional space, and the Euclidean square distance is the square of the Euclidean distance, and the distance between two vectors x and y is expressed by Equation 3 below. Is defined as:

The modified Euclidean square distance derived for applying the Euclidean square distance defined by Equation 3 to the present invention is as shown in Equation 4 below.

Here, "Vsab *" is the organic electromotive force measurement value of the AB phase search coil, "Vsbc" is the organic electromotive force measurement value of the BC phase search coil, "Vsca *" is the organic electromotive force measurement value of the CA phase search coil, "Vsab _k " Is the reference value of the organic electromotive force of the search coil of AB phase (0 ° to 90 °), "Vsbc _k " is the reference value of the organic electromotive force of the search coil of BC phase (0 ° to 90 °), and "Vsca _k " is the organic electromotive force of the search coil of CA phase Reference value (0 degrees-90 degrees).

That is, based on the formula of Equation 4, Euclidean of the organic electromotive force of the search coil (4ab, 4bc, 4ca) measured in the step (S130) and the Vs -θ _R reference value loaded in the step (S140) After calculating the squared distances, these values are compared to infer the position of the rotor 1 by selecting the output with the smallest Euclidean squared distance through the min operation.

For reference, assuming that the Vs-θ _R reference values are as shown in FIG. 5, the search coils 4ab and 4bc measured when the angles of the rotor 1 are 0 °, 13 °, 43 °, and 68 °, respectively. , 4ca) shows a simulation process by applying the organic electromotive force to the above Equation (4).

That is, as shown in FIG. 7A, the smallest value of Euclidean squared distance is 0 °, so it can be inferred that the position of the rotor 1 is 0 °. It can be inferred that the position of the rotor 1 is 13 ° because the small value is 13 °. Referring to FIG. 7C, the position of the rotor 1 is 43 ° because the smallest value of Euclidean squared distance is 43 °. It can be inferred that °, and looking at Figure 7d it can be inferred that the position of the rotor (1) is 68 ° because the simulation result Euclidean square distance is the smallest value of 68 °.

The control unit 10 generates a pulse width modulation signal for driving the motor M at the set speed according to the position of the rotor 1 estimated in the step S150, and outputs it to the inverter 30. In response to the pulse width modulation signal output from the controller 10, the inverter 30 pulse-modulates the DC power DC input from the DC power supply source (not shown) to the motor M, thereby providing a motor M. ) Is driven (S160).

In this case, the controller 10 may output information about the position of the rotor 1 estimated in the step S150 to a controller, a monitor, a printer, and the like.

Thereafter, the controller 10 checks the rotational speed of the motor 1 by the organic electromotive force value input from the search coils 4ab, 4bc, and 4ca through the A / D converter 40, and checks the rotational speed and By adjusting the pulse width modulation signal in accordance with the difference in the set speed, the motor 1 is driven at the set speed.

The present invention is described above by illustrating specific embodiments, but the present invention is not limited to the above embodiments. Those skilled in the art can easily make various changes and modifications to the present invention, and it should be noted that such variations or modifications are included within the scope of the present invention as long as the features of the present invention are used.

As described above, the present invention can detect the rotor position in the stationary state by the search coil. Therefore, according to the present invention, the switch reluctance motor can be detected by detecting the position of the rotor using only the search coil without having to provide a separate rotor position detecting sensor or forcibly fixing the position of the rotor at a specific position during stop. I can drive it.

As such, the switched reluctance motor, which detects the position of the rotor when stopped and driven only by the search coil, is relatively inexpensive, has a low trouble, durability, reliability, reduced volume, long service life, and improved environmental resistance. There are many advantages that can extend the use environment and enable precise initial start-up.

1 is a schematic diagram of a switched reluctance motor equipped with a search coil;

2 is a schematic diagram of a rotor position detection device of a switched reluctance motor according to a preferred embodiment of the present invention;

FIG. 3 is a schematic flowchart illustrating a process of acquiring and storing organic electromotive force reference data stored in a storage unit shown in FIG. 2;

Figure 4 is a graph measuring the organic electromotive force of the search coil for each phase when a single pulse voltage is input,

5 is a graph showing the distribution of organic electromotive force of the search coil for each phase that varies according to the rotor position;

FIG. 6 is a schematic flowchart for describing an operation of the controller illustrated in FIG. 2;

7 (a) to (d) are graphs showing a simulation process of position estimation of a rotor using Euclidean distance.

<Explanation of symbols for the main parts of the drawings>

1: rotor 2: stator

4ab, 4bc, 4ca: search coil 10: control unit

20: data table 30: inverter

40: A / D converter

Claims (10)

In a switched reluctance motor consisting of a stator and a rotor, A search coil for each phase wound around the pole of the stator, A storage unit for storing reference data on organic electromotive force of the search coil for each angle of the rotor; When a driving command is input, a control signal for applying a single pulse voltage is generated to the motor, and then an organic electromotive force for the search coil of each phase is detected, and the detected organic electromotive force value and the reference data stored in the storage unit are stored. Calculate the Euclidean square distance between the reference values for each angle, and obtain the reference value having the shortest Euclidean square distance from the detected organic electromotive force values, thereby estimating the initial position of the rotor and the result value according to the estimated position data. A control means for outputting; And a power supply means for driving by applying a voltage to the motor by a control signal applied from the control means. The method of claim 1, wherein the estimation of the initial position of the rotor, 『 Rotor position detection device of a switched reluctance motor, characterized in that performed according to the equation. However, "Vsab *" is the organic electromotive force measurement value of the AB phase search coil, "Vsbc" is the organic electromotive force measurement value of the BC phase search coil, "Vsca *" is the organic electromotive force measurement value of the CA phase search coil, "Vsab _k " Is the reference value of the organic electromotive force of the search coil of AB phase (0 ° to 90 °), "Vsbc _k " is the reference value of the organic electromotive force of the search coil of BC phase (0 ° to 90 °), and "Vsca _k " is the organic electromotive force of the search coil of CA phase Reference value (0 ° to 90 °). 2. The rotor position detection apparatus of claim 1, wherein the resultant value output from the control means is a control signal for driving the motor at a set speed. The apparatus of claim 1, wherein the resultant value output from the control means is information about an initial position of the rotor. In the method of detecting the rotor position of a switched reluctance motor consisting of a stator and a rotor and a search coil wound around each phase of the stator pole, Storing reference data on the organic electromotive force of the search coil for each rotor position; Applying a single pulse voltage to the motor when a drive command for the motor is input; Measuring an organic electromotive force for the search coil of each phase induced by the single pulse voltage; The Euclidean square distance between the measured value and the reference value for each angle of the reference data is calculated by comparing the organic electromotive force of the measured search coil with the stored reference data, and the Euclidean square distance with the measured value is the most. Estimating the initial position of the rotor by obtaining a short reference value, And a step of outputting a result value according to the estimated initial position data of the rotor. The reference data of the organic electromotive force of the search coil according to the position of the rotor according to claim 5, wherein the organic electromotive force is induced in the search coil by applying a single pulse voltage while adjusting the rotor of the motor by a set angle by experiment. Rotor position detection method of a switched reluctance motor, characterized in that to summarize the measured values of the organic electromotive force for each angle of the rotor. delete The method of claim 7, wherein the initial position estimate of the rotor by the Euclidean squared distance, Rotor position detection method of a switched reluctance motor, characterized in that performed according to the following equation. However, "Vsab *" is the organic electromotive force measurement value of the AB phase search coil, "Vsbc" is the organic electromotive force measurement value of the BC phase search coil, "Vsca *" is the organic electromotive force measurement value of the CA phase search coil, "Vsab _k " Is the reference value of the organic electromotive force of the search coil of AB phase (0 ° to 90 °), "Vsbc _k " is the reference value of the organic electromotive force of the search coil of BC phase (0 ° to 90 °), and "Vsca _k " is the organic electromotive force of the search coil of CA phase Reference value (0 ° to 90 °). 6. The rotor position detection method according to claim 5, wherein the output of the result value drives the motor at a set speed. The method of claim 5, wherein the output of the result value outputs information on the initial position of the rotor.