JP5425173B2 - Control device - Google Patents

Description

  The present invention relates to a control device.

  Conventionally, there is a control device that estimates the magnetic pole position of an IPM motor based on a current flowing in an IPM (Interior Permanent Magnet) motor without using a rotational position sensor.

  In Patent Document 1, in a control device for a rotating electrical machine, a high frequency position detection voltage is superimposed on a fundamental wave voltage for driving the rotating electrical machine, a current flowing through the rotating electrical machine is detected, and a high frequency position is detected from the detected current. It describes that a detection current is extracted and a rotor position of the rotating electrical machine is estimated based on the position detection current. Thereby, according to patent document 1, it is supposed that the rotor position of a rotary electric machine can be estimated even if the rotation speed of a rotary electric machine is a zero speed or a low speed area.

International Publication No. 2009/040965

  In the control device described in Patent Document 1, it is assumed that the rotational position (magnetic pole position) of the rotating electrical machine can be accurately estimated if the salient pole ratio of the rotating electrical machine (IPM motor) is simply larger than 1, that is, if there is a saliency. It is thought that.

  On the other hand, the present inventor has examined that, in order to accurately estimate the magnetic pole position of the IPM motor, it is not sufficient that the salient pole ratio is merely larger than 1, and the salient pole ratio of the IPM motor is greater than 1. It has been found that it is necessary to be greater than or equal to a large predetermined threshold (eg, 1.2). Furthermore, as a result of investigations, the present inventor has found that the salient pole ratio is smaller than the predetermined threshold value at high load even in the case of an IPM motor in which the salient pole ratio of the IPM motor during steady operation is greater than or equal to a predetermined threshold value. Therefore, it has been found that there is a possibility that the magnetic pole position of the IPM motor cannot be accurately estimated in the low speed range. In addition, it was originally found that an IPM motor having a salient pole ratio of an IPM motor during steady operation smaller than a predetermined threshold may not be able to accurately estimate the magnetic pole position of the IPM motor in a low speed range regardless of the load. . If the magnetic pole position of the IPM motor cannot be estimated accurately, the output torque in the low speed range may be limited.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a control device that can accurately estimate the magnetic pole position of an IPM motor in a low speed range.

  In order to solve the above-described problems and achieve the object, a control device according to one aspect of the present invention is a control device that controls an IPM motor in response to a d-axis current command and a q-axis current command, A correction unit that corrects the d-axis current command, a current detection unit that detects a current flowing through the IPM motor, and a parameter that depends on the salient pole ratio of the IPM motor is obtained based on the detected current. Based on the position estimation means for estimating the magnetic pole position in the IPM motor, the corrected d-axis current command, the q-axis current command, and the estimated magnetic pole position using the determined parameters A pulse width for generating a pulse width modulated logic signal based on a control means for generating a command, the generated voltage command, and a switching period used for pulse width modulation control Adjusting means and voltage applying means for applying an AC voltage for driving to the IPM motor based on the generated logic signal, and the voltage command generated by the control means is such that m is an integer of 3 or more. In this case, a position detection voltage having a period equal to m times the switching period and a phase different between phases is superimposed on the fundamental wave voltage for driving the IPM motor. The d-axis current command is corrected so that the salient pole ratio of the IPM motor is maintained at a threshold value or more.

  According to the present invention, since the decrease in the salient pole ratio of the IPM motor can be suppressed, the magnetic pole position of the IPM motor can be accurately estimated in the low speed range.

FIG. 1 is a diagram illustrating a configuration of a control device according to the first embodiment. FIG. 2 is a diagram illustrating the operation of the correction unit in the first embodiment. FIG. 3 is a diagram illustrating the operation of the correction unit in the modification of the first embodiment. FIG. 4 is a diagram illustrating the operation of the correction unit in the modification of the first embodiment. FIG. 5 is a diagram showing the operation of the correction means in the second embodiment. FIG. 6 is a diagram illustrating the configuration of the control device according to the basic mode.

  Embodiments of a control device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
First, before describing the control device according to the first embodiment, a basic mode for the control device according to the first embodiment will be described. The configuration of the control device 1 according to the basic mode will be described with reference to FIG.

  The control device 1 shown in FIG. 6 receives the d-axis current command id * and the q-axis current command iq * from the outside (for example, a host controller). The control device 1 controls an IPM (Interior Permanent Magnetic) motor M using a d-axis current command id * and a q-axis current command iq *.

  The IPM motor M has an embedded magnet structure in which a permanent magnet is embedded in the rotor. The d-axis represents the direction of the magnetic flux produced by the magnetic poles of the rotor (the central axis of the permanent magnet) and is also called the magnetic flux axis. The q axis represents an axis (an axis between permanent magnets) that is electrically and magnetically orthogonal to the d axis, and is also called a torque axis. Although not shown, the linkage flux due to the d-axis current id is limited because a magnet with low permeability is in the middle, whereas the linkage flux due to the q-axis current iq is a material having a higher permeability than the magnet. (E.g. silicon steel) passes through and becomes larger. During the steady operation of the IPM motor M, the d-axis magnetic resistance is larger than the q-axis magnetic resistance, and the d-axis inductance Ld is smaller than the q-axis inductance Lq. That is, the salient pole ratio Lq / Ld, which is the ratio of the q-axis inductance Lq to the d-axis inductance Ld, is greater than 1.

  The control device 1 estimates that the salient pole ratio of the IPM motor M during steady operation is greater than 1, that is, uses the saliency to estimate the rotor magnetic pole position, and uses the estimated magnetic pole position to generate the IPM. The drive of the motor M is controlled.

  As shown in FIG. 6, the control device 1 includes a current detection unit 10, a position estimation unit 20, a control unit 30, a pulse width modulation unit 40, and a voltage application unit 50.

  The current detection means 10 detects the current flowing through the IPM motor M. Specifically, the current detection unit 10 includes a current sensor 11 and a current sensor 12. The current sensor 11 detects, for example, a U-phase current iu flowing through the IPM motor M and supplies it to the position estimating unit 20 and the control unit 30. The current sensor 12 detects, for example, a V-phase current iv flowing through the IPM motor M and supplies it to the position estimating unit 20 and the control unit 30.

  Based on the current detected by the current detection means 10, the position estimation means 20 obtains a parameter (for example, ΔIαβ in Expression 7 described later) depending on the salient pole ratio Lq / Ld of the IPM motor M. Details of the parameters depending on the salient pole ratio of the IPM motor M will be described later. The position estimation means 20 estimates the magnetic pole position θp of the rotor in the IPM motor M using the obtained parameters. The position estimation unit 20 supplies the estimated magnetic pole position θp to the control unit 30.

  The control means 30 receives the d-axis current command id * and the q-axis current command iq * from the outside (for example, a host controller). The control means 30 receives the estimated magnetic pole position θp from the position estimation means 20. The control means 30 generates voltage commands Vup *, Vvp *, and Vwp * based on the d-axis current command id *, the q-axis current command iq *, and the estimated magnetic pole position θp.

  Specifically, the control means 30 includes a three-phase / two-phase converter 36, a coordinate converter 37, a subtractor 31a, a subtractor 31b, a d-axis current controller 32a, a q-axis current controller 32b, and a coordinate converter 33. , A two-phase / three-phase converter 34, a position detection voltage generator 38, an adder 35a, an adder 35b, and an adder 35c.

  Three-phase / two-phase converter 36 receives U-phase current iu from current sensor 11 and V-phase current iv from current sensor 12. The three-phase / two-phase converter 36 estimates the W-phase current iw from the U-phase current iu and the V-phase current iv, and the three-phase current vector (iu, iv, iw) is converted into a two-phase current vector (iα, iβ) on a fixed two-axis (α-β axis). The three-phase / two-phase converter 36 supplies the converted two-phase current vector (iα, iβ) to the coordinate converter 37.

  The coordinate converter 37 receives the two-phase current vector (iα, iβ) from the three-phase / two-phase converter 36. The coordinate converter 37 receives the estimated magnetic pole position θp from the position estimating means 20. The coordinate converter 37 uses the estimated magnetic pole position θp to convert the two-phase current vector (iα, iβ) on the fixed two axes (α-β axes) into the current vector on the two rotation axes (dq axes). Convert to (id, iq). The coordinate converter 37 supplies the converted d-axis current id to the subtractor 31a, and supplies the converted q-axis current iq to the subtractor 31b.

  The subtractor 31 a receives the d-axis current command id * from the outside, and receives the d-axis current id from the coordinate converter 37. The subtractor 31a subtracts the d-axis current id from the d-axis current command id * to obtain a deviation Δid, and supplies the obtained deviation Δid to the d-axis current controller 32a.

  The subtractor 31 b receives the q-axis current command iq * from the outside, and receives the q-axis current iq from the coordinate converter 37. The subtractor 31b subtracts the q-axis current iq from the q-axis current command iq * to obtain a deviation Δiq, and supplies the obtained deviation Δiq to the q-axis current controller 32b.

  The d-axis current controller 32a receives the deviation Δid from the subtractor 31a. The d-axis current controller 32a generates the d-axis fundamental voltage Vd * so that the deviation Δid approaches zero using proportional-integral control or the like. The d-axis current controller 32 a supplies the generated d-axis fundamental voltage Vd * to the coordinate converter 33.

  The q-axis current controller 32b receives the deviation Δiq from the subtractor 31b. The q-axis current controller 32b generates the q-axis fundamental voltage Vq * so that the deviation Δiq approaches zero by using proportional integral control or the like. The q-axis current controller 32 b supplies the generated q-axis fundamental wave voltage Vq * to the coordinate converter 33.

  The coordinate converter 33 receives the d-axis fundamental wave voltage Vd * from the d-axis current controller 32a, and receives the q-axis fundamental wave voltage Vq * from the q-axis current controller 32b. The coordinate converter 33 converts the fundamental wave voltage vector (Vd *, Vq *) on the two rotation axes (dq axis) to the fundamental wave voltage vector (Vα *, Vβ *) on the fixed two axes (α-β axis). ). The coordinate converter 33 supplies the converted fundamental voltage vector (Vα *, Vβ *) to the two-phase / three-phase converter 34.

  The two-phase / three-phase converter 34 receives the fundamental wave voltage vector (Vα *, Vβ *) from the coordinate converter 33. The two-phase / three-phase converter 34 converts a fundamental wave voltage vector (Vα *, Vβ *) on a fixed two axis (α-β axis) to a fundamental wave voltage vector on a fixed three axis (U-V-W axis). Convert to (Vu *, Vv *, Vw *). The two-phase / three-phase converter 34 supplies the converted fundamental wave voltage Vu * to the adder 35a, supplies the converted fundamental wave voltage Vv * to the adder 35b, and converts the converted fundamental wave voltage Vw *. Is supplied to the adder 35c.

  The position detection voltage generator 38 receives the value of the switching period Tc used for the pulse width modulation control from the pulse width modulation means 40. The switching period Tc has a period sufficiently shorter than the period of each fundamental wave voltage Vu *, Vv *, Vw * for three phases. The switching cycle Tc is set to an optimal value in advance in consideration of the electrical characteristics of the IPM motor M, the frequency of electromagnetic noise generated by the inverter drive, and the like.

  The position detection voltage generator 38 generates position detection voltages Vuh, Vvh, and Vwh using the switching period Tc. For example, the position detection voltage generator 38 has a period m · Tc in which the position detection voltages Vuh, Vvh, Vwh are each equal to m times the switching period Tc (m is an integer of 3 or more), and the position detection voltage generator 38 The position detection voltages Vuh, Vvh, Vwh are generated so that the phases of the use voltages Vuh, Vvh, Vwh are different from each other.

  If m is 1 or 2, a phase difference cannot be given to each of the three-phase position detection voltages Vuh, Vvh, Vwh, which is equal to a cycle m · Tc that is m times the switching cycle Tc. As a result, it becomes difficult for the position estimating means 20 to accurately obtain the magnetic pole position θp of the rotor.

  The position detection voltage generator 38 supplies the generated position detection voltage Vuh to the adder 35a, supplies the generated position detection voltage Vvh to the adder 35b, and generates the generated position detection voltage Vwh. It supplies to the adder 35c.

  The adder 35 a receives the fundamental voltage Vu * from the two-phase / three-phase converter 34 and receives the position detection voltage Vuh from the position detection voltage generator 38. The adder 35a adds (superimposes) the position detection voltage Vuh to the fundamental wave voltage Vu * to generate a voltage command Vup *. The adder 35 a supplies the generated voltage command Vup * to the pulse width modulation unit 40.

  The adder 35 b receives the fundamental voltage Vv * from the two-phase / three-phase converter 34 and receives the position detection voltage Vvh from the position detection voltage generator 38. The adder 35b adds (superimposes) the position detection voltage Vvh to the fundamental wave voltage Vv * to generate a voltage command Vvp *. The adder 35 b supplies the generated voltage command Vvp * to the pulse width modulation unit 40.

  The adder 35 c receives the fundamental voltage Vw * from the two-phase / three-phase converter 34 and receives the position detection voltage Vwh from the position detection voltage generator 38. The adder 35c adds (superimposes) the position detection voltage Vwh to the fundamental wave voltage Vw * to generate a voltage command Vwp *. The adder 35 c supplies the generated voltage command Vwp * to the pulse width modulation unit 40.

  The pulse width modulation means 40 is a pulse width modulated logic signal Vul, Vvl based on the voltage commands Vup *, Vvp *, Vwp * generated by the control means 30 and the switching period Tc used for pulse width modulation control. , Vwl is generated.

  Specifically, the pulse width modulation means 40 includes a switching period generator 41 and a pulse width modulation controller 42. The switching period generator 41 generates a value of the switching period Tc and supplies it to the position detection voltage generator 38 and the pulse width modulation controller 42.

  The pulse width modulation controller 42 receives the fundamental wave voltage Vup * from the adder 35a, receives the fundamental wave voltage Vvp * from the adder 35b, and receives the fundamental wave voltage Vwp * from the adder 35c. The pulse width modulation controller 42 receives the value of the switching period Tc from the switching period generator 41. The pulse width modulation controller 42 generates logic signals Vul, Vvl, Vwl that are pulse width modulated based on the fundamental voltages Vup *, Vvp *, Vwp * and the value of the switching period Tc. Examples of the pulse width modulation control method include a pulse width modulation control method using a triangular wave Cs as a carrier signal, a pulse width modulation control method using a sawtooth wave Wst as a carrier signal, and a pulse width modulation control method using an instantaneous spatial voltage vector Vs. A known method may be used. The pulse width modulation controller 42 supplies the generated logic signals Vul, Vvl, Vwl to the voltage applying unit 50.

  The voltage application unit 50 receives the logic signals Vul, Vvl, and Vwl from the pulse width modulation unit 40. The voltage applying unit 50 applies an AC voltage for driving to the IPM motor M based on the logic signals Vul, Vvl, and Vwl.

  Specifically, the voltage application unit 50 includes an inverter 51. Inverter 51 receives logic signals Vul, Vvl, and Vwl from pulse width modulation means 40. The inverter 51 has a plurality of switching elements (not shown), and each of the plurality of switching elements performs a switching operation at a predetermined timing in accordance with the logic signals Vul, Vvl, and Vwl. As a result, the inverter 51 generates an AC voltage for driving and applies it to the IPM motor M.

  Next, details of processing for obtaining the magnetic pole position θp of the rotor by the position estimating means 20 will be described in detail.

  For the IPM motor M, the voltage equation at the fixed orthogonal coordinates (α-β axis) can be expressed as the following Equation 1.

  Assuming that the IPM motor M is stopped or operating in a low speed region, ω = 0, and if the differential operator P is replaced with the Laplace operator s, the currents iαs and iβs in the fixed orthogonal coordinates are The following formula 2 is obtained.

  Now, when position detection voltages Vuh, Vvh, Vwh having an angular frequency ωh sufficiently higher than the angular frequency of the AC voltage for driving the IPM motor M from the position detection voltage generator 38 are applied, R << Lα When ωh and R << Lβ · ωh are established (when s = jωh (j is an imaginary unit)) and the influence of the stator resistance R is ignored, the above Equation 2 becomes Equation 3 below.

また、位置検出用電圧発生器３８より印加する位置検出用電圧Ｖｕｈ，Ｖｖｈ，Ｖｗｈは、固定直交座標では下記の数式４のように表すことができる。

Further, the position detection voltages Vuh, Vvh, Vwh applied from the position detection voltage generator 38 can be expressed by the following mathematical expression 4 in fixed orthogonal coordinates.

数式４の固定直交座標での位置検出用電圧は、下記の数式５で表される。

The position detection voltage in the fixed orthogonal coordinates of Expression 4 is expressed by Expression 5 below.

  Substituting the value of the voltage for position detection of the above formula 5 into [Vαs Vβs] of the fixed orthogonal coordinate system in the above formula 3 and setting s = jωh (j is an imaginary unit), the following formula 6 is obtained.

  As shown in Equation 6 above, it can be seen that the amplitudes of the currents iαs and iβs in the fixed orthogonal coordinates include the rotor magnetic pole position θ (= rotor magnetic pole position θp). Therefore, the amplitudes Iαs and Iβs of the currents iαs and iβs in the fixed orthogonal coordinates are extracted by a Fourier transformer (not shown). That is, high-frequency currents iαs and iβs based on position detection voltages Vuh, Vvh, and Vwh in the rotating electrical machine current are extracted by a Fourier transformer, and the amplitudes Iαs and Iβs are obtained. Based on the extracted amplitudes Iαs and Iβs, a term including only the magnetic pole position θ of the rotor can be extracted by performing an operation as shown in the following formula 7. In order to realize this calculation, from the output (Iβs · Iβs) of the first multiplier and the second multiplier (both not shown) that square the amplitudes Iαs and Iβs, respectively, (Iαs · Iαs) is obtained. A subtracter (not shown) that outputs ΔIαβ including only information on the magnetic pole position θ of the rotor is used.

  A position calculator (not shown) that receives the output of the subtractor extracts only cos 2θ by dividing ΔIαβ in Equation 7 above by Equation 8 below. Then, θ (rotor magnetic pole position θp) is calculated by calculating the inverse cosine of cos 2θ. The calculation of the rotor magnetic pole position θp is not the inverse cosine calculation, but a table storing the value of cos 2θ is prepared, and the magnetic pole position θp of the rotor is obtained based on the value of cos 2θ stored in the storage device. Also good.

  Here, ΔIαβ is a parameter depending on the salient pole ratio Lq / Ld of the IPM motor M, as shown in Equations 1-7. Then, in the control device 1 shown in FIG. 6, it is assumed that the magnetic pole position of the IPM motor M can be accurately estimated if the salient pole ratio of the IPM motor M) is simply larger than 1, that is, if there is a salient polarity. It is done.

  On the other hand, the present inventor conducted a comparative study on the salient pole ratio and the estimation accuracy of the magnetic pole position. In order to accurately estimate the magnetic pole position of the IPM motor M, the salient pole ratio is simply larger than 1. It has been found that the salient pole ratio of the IPM motor M is not sufficient and needs to be equal to or greater than a predetermined threshold (for example, 1.2) greater than 1. Furthermore, the present inventor has examined that even if the IPM motor M has a salient pole ratio Lq / Ld of the IPM motor M during steady operation that is equal to or higher than a predetermined threshold value (for example, 1.2). It has been found that the magnetic pole position of the IPM motor M may not be accurately estimated in the low speed range because the salient pole ratio Lq / Ld may drop below a predetermined threshold value during loading. That is, as the load increases, the q-axis current command iq * increases. When the q-axis current command iq * increases, the q-axis inductance Lq may be attenuated due to magnetic saturation and the salient pole ratio Lq / Ld may decrease. Therefore, the magnetic pole position of the IPM motor M may not be accurately estimated in the low speed range. I found that there is sex. If the magnetic pole position of the IPM motor M cannot be accurately estimated, the output torque in the low speed range may be limited.

  Next, the control device 100 according to the first embodiment will be described with reference to FIG. Below, it demonstrates centering on a different part from the control apparatus 1 concerning a basic form.

  The control device 100 further includes a correction unit 160. The correction unit 160 receives the d-axis current command id * and the q-axis current command iq * from the outside (for example, a host controller). The correcting unit 160 corrects the d-axis current command id * so that the salient pole ratio of the IPM motor M is equal to or greater than the threshold value TH. The threshold value TH is a value that is experimentally determined in advance so that the required accuracy of the magnetic pole position estimation by the position estimation means 20 in the low speed region of the IPM motor M can be satisfied. The threshold value TH is, for example, 1.2. The correction unit 160 supplies the corrected d-axis current command id ** and the control unit 30 and also supplies the received q-axis current command iq * to the control unit 30 as it is.

  Specifically, the correction unit 160 includes a calculator 161 and an adder 162. Arithmetic unit 161 receives q-axis current command iq * from the outside. The calculator 161 calculates a correction amount Δid * for the d-axis current command id * according to the q-axis current command iq *. For example, correction information as shown in FIG. The arithmetic unit 161 uses this correction information to add a positive correction amount Δid * to the d-axis current command in response to the magnitude of the q-axis current command iq * exceeding the second threshold value iq * 1. To do. That is, in response to the fact that the magnitude of the q-axis current command iq * exceeds the second threshold value iq * 1 and the load is estimated to be high (that is, when the load is high), the d-axis current command id Increase the value of *.

  More specifically, the calculator 161 sets the correction amount Δid * to zero when the magnitude of the q-axis current command iq * is equal to or smaller than the second threshold value iq * 1. The arithmetic unit 161 gradually increases the correction amount Δid * from zero toward the positive direction as the magnitude of the q-axis current command iq * exceeds the second threshold value iq * 1 and approaches the third threshold value iq * 2. . When the magnitude of the q-axis current command iq * exceeds the third threshold value iq * 2, the calculator 161 sets the correction amount Δid * to the maximum value Δid * max.

  The third threshold value iq * 2 is determined by experimentally acquiring the relationship between the salient pole ratio Lq / Ld of the IPM motor M and the q-axis current command iq * when correction by the correction means 160 is not performed. Value. For example, the third threshold value iq * 2 is a value that is lower by a predetermined margin than the value of the q-axis current command iq * where the salient pole ratio of the IPM motor M starts to become smaller than a predetermined threshold value TH (for example, 1.2). .

  Further, the third threshold value iq * 2 has a value larger than the second threshold value iq * 1 by a predetermined amount. Thereby, it is possible to perform the correction process while suppressing a rapid change in the d-axis current.

  Then, the arithmetic unit 161 supplies the obtained correction amount Δid * to the adder 162 (for example, as needed).

  Adder 162 receives d-axis current command id * from the outside, and receives correction amount Δid * from calculator 161. The adder 162 adds the correction amount Δid * to the d-axis current command id * and supplies the addition result to the control means 30 as a corrected d-axis current command id **. Thereby, the control means 30 outputs the voltage commands Vup *, Vvp *, Vwp * based on the corrected d-axis current command id **, the q-axis current command iq *, and the estimated magnetic pole position θp. Generate.

  As described above, in the first embodiment, the correction unit 160 sets the d-axis current command id * so that the salient pole ratio Lq / Ld of the IPM motor M is maintained at a threshold value (for example, 1.2) or more. to correct. Thereby, since the fall of the salient pole ratio Lq / Ld of the IPM motor M can be suppressed, the magnetic pole position of the IPM motor M can be accurately estimated in the low speed region. Therefore, sensorless control can be stably performed in the low speed range, and output torque in the low speed range can be secured.

  In the first embodiment, the correction unit 160 determines that the d-axis current command id * has a positive correction amount Δid in response to the magnitude of the q-axis current command iq * exceeding the second threshold value iq * 1. Add *. As a result, there is a concern that at the time of high load, that is, the q-axis current command iq * increases and the q-axis inductance Lq is attenuated due to the influence of magnetic saturation and the salient pole ratio Lq / Ld of the IPM motor M is reduced. In the situation, the d-axis current command id * can be increased, and the d-axis inductance Ld can also be attenuated due to the effect of magnetic saturation, so that the salient pole ratio Lq / Ld of the IPM motor M is maintained at a threshold value (for example, 1.2) or more. You can make it.

  In the first embodiment, the case where one piece of correction information (see FIG. 2) is set in the calculator 161 is described as an example. However, a plurality of pieces of correction information are set in the calculator 161. May be.

  For example, in addition to the correction information shown in FIG. 2, correction information shown in FIG. 3 may be set in the calculator 161. In the correction information shown in FIG. 3, the maximum value Δid * max2 of the correction amount Δid * is different from the maximum value Δid * max of the correction amount Δid * in the correction information shown in FIG. For example, the maximum value Δid * max2 in FIG. 3 is larger than the maximum value Δid * max in FIG. In this case, the arithmetic unit 161 acquires a characteristic value such as a motor constant of the IPM motor M that is currently controlled, and based on the acquired characteristic value, the correction information shown in FIG. 2 and the correction information shown in FIG. Either correction information is selected. For example, when the maximum value Δid * max2 in FIG. 3 is larger than the maximum value Δid * max in FIG. 2, the computing unit 161 attenuates the q-axis inductance Lq with respect to the increase in the q-axis current command iq * from the acquired characteristic value. When it is determined that the degree is equal to or smaller than the fourth threshold, the correction information shown in FIG. 2 is selected, and it is determined that the degree of attenuation of the q-axis inductance Lq with respect to the increase in the q-axis current command iq * is larger than the fourth threshold. If so, the correction information shown in FIG. 3 is selected. Then, the calculator 161 calculates the correction amount Δid * using the selected correction information. Thereby, even when the control target of the control device 100 is replaced with an IPM motor M having a different degree of attenuation of the q-axis inductance Lq with respect to an increase in the q-axis current command iq *, the salient pole ratio Lq / Ld of the IPM motor M is The threshold value (for example, 1.2) can be maintained.

  Alternatively, for example, the correction information shown in FIG. 4 may be set in the computing unit 161 in addition to the correction information shown in FIG. In the correction information shown in FIG. 4, the second threshold value iq * 3 is different from the second threshold value iq * 1 in the correction information shown in FIG. 2, and the third threshold value iq * 4 is the second threshold value in the correction information shown in FIG. 3 is different from the threshold value iq * 2. For example, the second threshold value iq * 3 in FIG. 4 is smaller than the second threshold value iq * 1 in FIG. 2, and the third threshold value iq * 4 in FIG. 4 is smaller than the third threshold value iq * 2 in FIG. In this case, the arithmetic unit 161 acquires a characteristic value such as a motor constant of the IPM motor M that is currently controlled, and based on the acquired characteristic value, the correction information shown in FIG. 2 and the correction information shown in FIG. Either correction information is selected. For example, the second threshold value iq * 3 in FIG. 4 is smaller than the second threshold value iq * 1 in FIG. 2, and the third threshold value iq * 4 in FIG. 4 is smaller than the third threshold value iq * 2 in FIG. When it is determined from the acquired characteristic value that the value of the q-axis current command iq * at which the q-axis inductance Lq starts to attenuate is less than or equal to the fifth threshold value, the computing unit 161 displays the correction information shown in FIG. When it is determined that the value of the q-axis current command iq * at which the q-axis inductance Lq starts to attenuate is determined to be larger than the fifth threshold, the correction information shown in FIG. 2 is selected. Then, the calculator 161 calculates the correction amount Δid * using the selected correction information. Thereby, even when the control target of the control device 100 is replaced with the IPM motor M having a different q-axis current command iq * value at which the q-axis inductance Lq starts to attenuate, the salient pole ratio Lq / Ld of the IPM motor M is The threshold value (for example, 1.2) can be maintained.

Embodiment 2. FIG.
Next, the control device 100 according to the second embodiment will be described. Below, it demonstrates focusing on a different part from Embodiment 1. FIG.

  In the first embodiment, the control target of the control device 100 is an IPM motor M in which the salient pole ratio Lq / Ld of the IPM motor M during steady operation is equal to or greater than a predetermined threshold value TH (for example, 1.2). . On the other hand, in the second embodiment, the control object of the control device 100 is such that the salient pole ratio Lq / Ld of the IPM motor M during steady operation is larger than 1 and smaller than a predetermined threshold value TH (for example, 1.2). Such an IPM motor M.

  In connection with this, the present inventor has examined and found that the IPM motor M originally has a salient pole ratio Lq / Ld of the IPM motor M during steady operation smaller than a predetermined threshold value TH (for example, 1.2). Regardless, the inventors have found that there is a possibility that the magnetic pole position of the IPM motor M cannot be accurately estimated in the low speed range. If the magnetic pole position of the IPM motor M cannot be accurately estimated, the output torque in the low speed range may be limited.

  In contrast, in the second embodiment, the correction unit 160 sets the d-axis current command id * so that the salient pole ratio Lq / Ld of the IPM motor M is maintained at a threshold value TH (for example, 1.2) or more. to correct. Specifically, the calculator 161 adds the positive correction amount Δid * to the d-axis current command regardless of the magnitude of the q-axis current command iq *. For example, correction information as shown in FIG. The calculator 161 uses this correction information to add a positive correction amount Δid * to the d-axis current command regardless of the magnitude of the q-axis current command iq *. That is, the value of the d-axis current command id * is increased regardless of the size of the load.

  More specifically, the calculator 161 sets the correction amount Δid * to the maximum value Δid * max regardless of the magnitude of the q-axis current command iq *. Then, the arithmetic unit 161 supplies the obtained correction amount Δid * to the adder 162 (for example, as needed).

  As described above, in the second embodiment, the correction unit 160 adds the positive correction amount Δid * to the d-axis current command id * regardless of the magnitude of the q-axis current command iq *. Thereby, when the control object of the control device 100 is the IPM motor M in which the salient pole ratio Lq / Ld of the IPM motor M during steady operation is smaller than a predetermined threshold value TH (for example, 1.2), The d-axis current command id * can be increased and the d-axis inductance Ld can be attenuated due to the effect of magnetic saturation, so that the salient pole ratio Lq / Ld of the IPM motor M is maintained at a threshold TH (for example, 1.2) or more. You can make it.

  In the second embodiment, the case where one piece of correction information (see FIG. 5) is set in the calculator 161 is described as an example. However, a plurality of pieces of correction information are set in the calculator 161. May be.

  For example, the correction information shown in FIG. 2 may be set in the calculator 161 in addition to the correction information shown in FIG. In this case, the arithmetic unit 161 acquires a characteristic value such as a motor constant of the IPM motor M that is currently controlled, and based on the acquired characteristic value, the correction information shown in FIG. 2 and the correction information shown in FIG. Either correction information is selected. For example, when the arithmetic unit 161 determines from the acquired characteristic value that the salient pole ratio Lq / Ld of the IPM motor M during steady operation is smaller than a predetermined threshold value TH (for example, 1.2), FIG. 2 is selected, and it is determined that the salient pole ratio Lq / Ld of the IPM motor M during steady operation is equal to or greater than a predetermined threshold TH (for example, 1.2), the correction information shown in FIG. select. Then, the calculator 161 calculates the correction amount Δid * using the selected correction information. Thereby, the control target of the control device 100 is between the IPM motor M in which the salient pole ratio Lq / Ld of the IPM motor M in the steady operation is smaller than the predetermined threshold value TH and the IPM motor M having the predetermined threshold value TH or more. Even when it is replaced, the salient pole ratio Lq / Ld of the IPM motor M can be maintained at a threshold TH (for example, 1.2) or more.

  As described above, the control device according to the present invention is useful for controlling the IPM motor.

DESCRIPTION OF SYMBOLS 1 Control apparatus 10 Current detection means 11 Current sensor 12 Current sensor 20 Position estimation means 30 Control means 31a, 31b, 31c Subtractor 32a d-axis current controller 32b q-axis current controller 33 Coordinate converter 34 Two-phase / three-phase conversion 35a, 35b, 35c Adder 36 Three-phase / two-phase converter 37 Coordinate converter 38 Position detection voltage generator 40 Pulse width modulation means 41 Switching period generator 42 Pulse width modulation controller 50 Voltage application means 51 Inverter 100 Control device 160 Correction means 161 Calculator 162 Adder

Claims (3)

A control device that receives the d-axis current command and the q-axis current command and controls the IPM motor,
Correction means for correcting the d-axis current command;
Current detection means for detecting a current flowing through the IPM motor;
Position estimation means for obtaining a parameter depending on the salient pole ratio of the IPM motor based on the detected current, and estimating a magnetic pole position in the IPM motor using the obtained parameter;
Control means for generating a voltage command based on the corrected d-axis current command, the q-axis current command, and the estimated magnetic pole position;
Pulse width modulation means for generating a pulse width modulated logic signal based on the generated voltage command and a switching period used for pulse width modulation control;
Voltage applying means for applying an AC voltage for driving to the IPM motor based on the generated logic signal;
With
The voltage command generated by the control means has a period equal to m times the switching period with respect to the fundamental wave voltage for driving the IPM motor when m is an integer of 3 or more and between each phase. Voltage for position detection with different phase is superimposed,
The controller corrects the d-axis current command so that the salient pole ratio of the IPM motor is maintained at a threshold value or more. The correction unit adds a positive correction amount to the d-axis current command in response to the magnitude of the q-axis current command exceeding a second threshold value. Control device. The control device according to claim 1, wherein the correction unit adds a positive correction amount to the d-axis current command regardless of the magnitude of the q-axis current command.

Images