JP4668017B2 - Brushless DC motor control device - Google Patents

Description

  The present invention relates to a control device for a brushless DC motor.

Conventionally, for example, a harmonic voltage that does not contribute to the rotation of the rotor is applied to a voltage command value for controlling a brushless DC motor, and a rotor that indicates the position of the rotor from a phase current that flows in each phase by this harmonic voltage. A control device that detects the angle of the rotor magnetic pole from a predetermined reference rotational position and determines the direction of the rotor magnetic pole by applying a magnetic pole detection voltage corresponding to the field direction to the voltage command value is known. (For example, refer to Patent Document 1).
In this control device, when a magnetic field is generated in the field direction by the magnetic pole detection voltage, a saturation state in which the direction of the generated magnetic field and the field direction are the same direction, and the direction of the generated magnetic field and the field direction are The direction of the magnetic poles of the rotor is discriminated based on the change in the state of the phase current flowing in each phase in the non-saturated state which is the opposite direction.
JP 2005-151714 A

By the way, in the control device according to an example of the above prior art, the magnet temperature of the rotor is not changed when the magnetic pole discrimination processing for discriminating the direction of the magnetic pole of the rotor by applying the magnetic pole detection voltage to the voltage command value is performed. Is a precondition, and the state in which the magnet temperature of the rotor changes is not considered. However, as the magnet temperature of the rotor increases, the magnetic flux density of the permanent magnet changes so as to decrease. Therefore, when the change in the magnet temperature of the rotor is ignored, the determination accuracy of the magnetic pole determination process decreases, and the magnetic pole There is a risk that the orientation of the camera will be misjudged or the discrimination itself will be impossible.
In addition, when the current supplied to the stator of the brushless DC motor is excessively increased, demagnetization that reduces the magnetic force of the permanent magnet of the rotor may occur due to the magnetic field generated by the excessive current. Since the permanent magnet of the rotor is likely to be demagnetized as the magnet temperature increases, the upper limit current at which the demagnetization action is within a predetermined allowable range tends to decrease as the magnet temperature of the rotor increases. Will change. For this reason, if the magnetic pole discrimination process is executed in a state where the change in the magnet temperature of the rotor is ignored, the current that is supplied to the stator during execution of the magnetic pole discrimination process when the magnet temperature is relatively high is within an allowable range. The current may be exceeded and the permanent magnet may be excessively demagnetized.
The present invention has been made in view of the above circumstances, and is a brushless DC motor capable of improving the discrimination accuracy while preventing the permanent magnet of the rotor from being excessively demagnetized during the magnetic pole discrimination process. An object is to provide a control device.

In order to solve the above problems and achieve the object, a brushless DC motor control device according to the present invention includes a permanent magnet type rotor (for example, the rotor 2 in the embodiment). A harmonic voltage (for example, inspection voltages (Hd ^, Hq ^) in the embodiment) is applied to the stator winding (for example, the armatures 3, 4, 5 in the embodiment) of the brushless DC motor, A brushless DC motor control device including position detection means (for example, an angle detection unit 25 in the embodiment) for detecting the position of the rotor from a motor current generated by the high-frequency voltage, the field direction of the rotor A magnetic pole detection means (for example, the angle detection unit 25 in the embodiment) for applying a magnetic pole detection voltage according to the above to the stator winding to determine the direction of the magnetic pole of the rotor, and the magnetic pole detection by the magnetic pole determination means. Magnetic pole discriminating current changing means (for example, the magnetic pole in the embodiment) that increases the field axis current as the magnet temperature of the rotor (for example, the magnet temperature TM in the embodiment) increases during the process. Discriminating current command unit 29, step S06) and prohibiting execution of the magnetic pole discriminating process by the magnetic pole discriminating means when the magnet temperature exceeds a predetermined threshold temperature (for example, the first threshold temperature T1 in the embodiment). And a starting means (for example, step S02 in the embodiment) for starting the brushless DC motor by forced commutation , wherein the magnetic pole discriminating current changing means has a first magnet temperature lower than the predetermined threshold temperature. When the temperature is equal to or higher than two threshold temperatures (for example, the second threshold temperature T2 in the embodiment), the field axis current is increased, and the predetermined threshold temperature is determined when the stator winding is It is characterized in that the magnets of the rotor by current supplied is a magnet temperature corresponding to the case where the demagnetization.

  According to the brushless DC motor control device having the above configuration, the magnetic pole discrimination current changing means is set so that the field axis current increases as the rotor magnet temperature increases. Along with the increase, even if the magnetic flux density of the permanent magnet is changed to a decreasing tendency, it is possible to prevent the determination accuracy of the magnetic pole determination process from decreasing.

  According to the brushless DC motor control apparatus having the above-described configuration, when the magnet temperature exceeds a predetermined threshold temperature, the starting means energizes the stator winding regardless of forced commutation, that is, the magnetic pole position of the rotor. Since the brushless DC motor is started by sequentially commutating, it is unnecessary to apply a field current for magnetic pole discrimination to the stator, and the predetermined current is allowed for the brushless DC motor in which the current supplied to the stator is relatively high. The brushless DC motor can be accurately started while preventing the permanent magnet from being excessively demagnetized by exceeding the upper limit current within the range.

Further, in the brushless DC motor control device according to the second aspect of the present invention, the rotor is connected to a drive shaft of a vehicle and a crankshaft of an internal combustion engine, and the brushless DC motor is capable of driving the vehicle to travel and the internal combustion engine. When the magnet temperature is lower than a predetermined threshold temperature (for example, the first threshold temperature T1 in the embodiment), the magnetic pole discriminating current changing means starts the brushless DC motor and starts the brushless DC motor. the DC motor during the execution of the pole discrimination processing by the magnetic pole discrimination means upon starting the internal combustion engine, with that magnet temperature of the rotor increases, Ru der shall be set as field axis current increases It is characterized by that.

According to the brushless DC motor control device having the above configuration, the magnetic pole discrimination current changing means is set so that the field axis current increases as the rotor magnet temperature increases. Along with the increase, even if the magnetic flux density of the permanent magnet is changed to a decreasing tendency, it is possible to prevent the determination accuracy of the magnetic pole determination process from decreasing.
Further, when the magnet temperature exceeds a predetermined threshold temperature, the starting means starts the brushless DC motor by forcibly commutating, that is, sequentially energizing the stator winding regardless of the magnetic pole position of the rotor. Therefore, it is unnecessary to apply a field current for magnetic pole discrimination to the stator, and the current supplied to the stator exceeds the upper limit current within a predetermined allowable range for the brushless DC motor in a relatively high temperature state. The internal combustion engine can be accurately started while preventing the permanent magnet from being demagnetized excessively.

Furthermore, in the brushless DC motor control device according to the third aspect of the present invention , when the magnet temperature exceeds a predetermined threshold temperature (for example, the first threshold temperature T1 in the embodiment), it is mounted on the vehicle. And a starting means (for example, step S02 in the embodiment) for starting the internal combustion engine by the starting device.

According to the brushless DC motor control device having the above configuration, the magnetic pole discrimination current changing means is set so that the field axis current increases as the rotor magnet temperature increases. Along with the increase, even if the magnetic flux density of the permanent magnet is changed to a decreasing tendency, it is possible to prevent the determination accuracy of the magnetic pole determination process from decreasing.
Further, when the magnet temperature exceeds a predetermined threshold temperature, the starting means does not start the internal combustion engine by the brushless DC motor but starts the internal combustion engine by another starting device mounted on the vehicle. When starting the motor, it is not necessary to apply a field current for magnetic pole discrimination to the stator, and the current supplied to the stator exceeds the upper limit current within a predetermined allowable range for the brushless DC motor in a relatively high temperature state. Thus, the internal combustion engine can be started accurately while preventing the permanent magnet from being demagnetized excessively.

According to the brushless DC motor control device of the first aspect of the present invention, even if the magnetic flux density of the permanent magnet changes to a decreasing tendency as the magnet temperature of the rotor increases, the magnetic pole discrimination processing It can be prevented that the discrimination accuracy is reduced.
Furthermore , it is not necessary to apply a field current for determining the magnetic pole to the stator, and the current supplied to the stator exceeds the upper limit current within a predetermined allowable range for the brushless DC motor in a relatively high temperature state, so that the permanent magnet Is prevented from being excessively demagnetized, and the brushless DC motor can be accurately started.
Further, according to the brushless DC motor control device of the present invention described in claim 2 and claim 3, it is not necessary to supply a field current for magnetic pole discrimination to the stator when starting the brushless DC motor, and While preventing the permanent magnet from being demagnetized excessively when the energized current exceeds the upper limit current within a predetermined allowable range for the brushless DC motor in a relatively high temperature state, the internal combustion engine is accurately Can be started.

Embodiments of a brushless DC motor control apparatus according to the present invention will be described below with reference to the accompanying drawings.
(Principle of rotor position detection)
First, the principle of rotor position detection will be described below. In the following description, a mathematical expression or the like in which a hat symbol (^) is added on a character (for example, θ) is equivalent to a character in which a hat symbol (^) is added on the right side of the character (θ ^). It is.

  As shown in FIG. 1A, when the brushless DC motor 1 includes a salient pole type rotor 2, the gap between the rotor 2 and the U-phase, V-phase, and W-phase armatures 3, 4, and 5 The magnetic resistance changes periodically, and this change changes twice during one rotation of the rotor 2, that is, one cycle while the rotor 2 makes a half rotation. The magnetic resistance of the gap is maximized when the rotor 2 is in the position A in the figure, and is minimized when the rotor 2 is in the position B in the figure.

  Assuming that the average value of the magnetoresistance of the gap per cycle is “0.5”, the magnetoresistances Ru, Rv, and Rw in the U phase, V phase, and W phase are as follows (1 ) To (3).

  Here, the magnetic resistance Rgu of the gap as viewed from the U phase can be obtained by the following equation (4).

  Therefore, assuming that the U-phase is a unit winding, the U-phase self-inductance Lu can be obtained by the following equation (5).

  The mutual inductance Muw between the U phase and the W phase and the mutual inductance Muv between the U phase and the V phase can be obtained from the following equations (6) and (7), respectively, from the configuration of the magnetic circuit.

  Similarly, the self-inductance and the mutual inductance can be obtained for the V-phase and the W-phase. Accordingly, the voltage equation of the brushless DC motor 1 having saliency sets the direct current component of the self-inductance of each phase to l, If the fluctuation of l is Δl and the direct current of the mutual inductance between the phases is m, it can be expressed by the following equation (8).

  Here, Vu, Vv, and Vw are voltages applied to U-phase, V-phase, and W-phase armatures, respectively, and Iu, Iv, and Iw are U-phase, V-phase, and W-phase armatures 3, 4, 5, r is the electrical resistance of the U-phase, V-phase, and W-phase armatures 3, 4, and 5, ω is the electrical angular velocity of the rotor 2, and Ke is the induced voltage constant.

  Furthermore, when the electrical angular velocity ω is substantially “0”, the influence of the induced voltage and the change in the angular velocity of the rotor 2 is small, and the voltage drop due to the resistance r is negligible, the above equation (8) can be expressed by the following ( It can be approximated by equation (9).

  Here, when the above equation (9) is transformed into an equation based on the interphase current and the correlation voltage, the following equation (10) is obtained.

  Further, since the inductance matrix of the above equation (10) is regular, the above equation (10) can be transformed into the following equations (11) and (12).

  Further, when the brushless DC motor 1 is handled in a so-called dq coordinate system, the following (13) is used by using an estimated value (θ ^) of the rotor angle (that is, the rotation angle of the magnetic pole of the rotor 2 from a predetermined reference rotation position). ), When the three-phase / dq conversion expressed by the equation (14) is applied to the above equation (11), the estimated value (θ ^) of the rotor angle and the actual value (θ) are equal (θ ^ = θ). The following equation (15) is obtained. In the following equation (15), the inductances Ld and Lq are described by the following equations (16) and (17).

  Here, when the rotor angle (θ) in the above equation (11) is an estimated value deviated by (θe) from the actual value of the rotor angle, Id that has been three-phase / dq converted using this estimated value The relationship of the following formulas (18) and (19) holds between ^, Iq ^, Vd ^, Vq ^ and Id, Iq, Vd, Vq converted using the actual values of the rotor angle. .

  However, θe is the phase difference between the actual value and the estimated value of the rotor angle. Therefore, the following relational expression (20) is derived.

  As in the case of the above equation (8), when the electrical angular velocity ω is substantially “0”, the influence of the induced voltage and the change in the angle of the rotor 2 is small, and the voltage drop due to the resistance r is negligible. The above equation (20) can be approximated by the following equation (21).

  Further, the differential period (dt) in the above equation (21) is set to the length (Δt) of the control cycle, and in an appropriate control cycle, based on the estimated value (θ ^) of the rotor angle of the brushless DC motor 1, When the dq conversion process is performed, the d-axis voltage and the q-axis voltage in this control cycle are {Vd (1), Vq (1)}, and the amount of change between the d-axis actual current and the q-axis actual current is {ΔId ( 1), ΔIq (1)}, the above equation (21) is expressed in the form of the following equation (22).

  Similarly, the d-axis voltage and the q-axis voltage in the next control cycle are {Vd (2), Vq (2)}, and the amount of change between the d-axis actual current and the q-axis actual current is {ΔId (2), ΔIq ( 2)}, the above expression (21) is expressed in the form of the following expression (23).

  Then, it is assumed that n control cycles are included in the predetermined period, and the basic voltage string data is set by n pieces of data as shown in the following equation (24), and the modulation coefficient is set to s ( k) (k = 1, 2,..., time series number of a predetermined period), the inspection voltage is expressed in the form of the following equation (25).

  Where Hdq ^ (x) is the output level of the test voltage in the xth control cycle after the start of superimposition of the test voltage, and i is the time series number of the control cycle in one cycle of the test voltage (i = 1) , 2,..., N), k is the time series number of the cycle of the test voltage (k = 1, 2,...), And Hd ^ (x) is the xth control cycle after the superposition of the test voltage is started. The d-axis component of the output level of the inspection voltage at Hq ^ (x) is the q-axis component of the output level of the inspection voltage in the xth control cycle after the superposition of the inspection voltage is started.

  On the other hand, in the energization control to the brushless DC motor 1, the deviation between the d-axis command current (Id_c) and the d-axis actual current (Id_s) is reduced so that the d-axis feedback voltage (Vd_fb) is, for example, (26 In the same manner, the deviation between the q-axis command voltage (Iq_c) and the q-axis actual current (Iq_s) is reduced, and the q-axis feedback voltage (Vq_fb) is calculated by the following expression (27). To do.

In this case, the differential voltage of the test voltage (Hdq) between the control cycles is set as in the following equation (28), and the d-axis of the next control cycle is calculated by the following equations (29) and (30). By setting the voltage and the q-axis voltage {Vd ^ (2), Vq ^ (2)}, the difference voltage (dVd_fb) of the d-axis feedback voltage in the current control cycle relative to the d-axis voltage in the previous control cycle and the previous time The direction of the voltage vector whose component is the difference voltage (dVq_fb) of the q-axis voltage in the current control cycle relative to the q-axis voltage in the current control cycle is the difference in the d-axis inspection voltage from the previous control cycle in the current control cycle. It is possible to limit the direction of the voltage vector having the voltage (k1) and the difference voltage (k2) between the q-axis inspection voltage as components.
However, Vd_old is the d-axis voltage in the previous control cycle, and Vq_old is the q-axis voltage in the previous control cycle.

  For this reason, when the above formulas (22) and (23) are subtracted side by side, the following formula (31) is obtained.

  Then, the following expression (32) is obtained by modifying the above expression (31), and the following expression (33) is obtained by summing up the expression (32) for each of the n control cycles in the predetermined period. .

  In the above equation (33), when n> 1, the matrix C is an independent voltage vector {dV (i), dV (j), 1 ≦ i ≦ n, 1 ≦ j ≦ n, i ≠. If j} is 2 or more, it is a full rank rank, and is a double angle of the phase difference (θe = θ−θ ^) between the actual value (θ) of the rotor angle of the brushless DC motor 1 and the estimated value (θ ^). The least square estimated value of the sine reference value (Vs ^) corresponding to the sine value and the cosine reference value (Vc ^) corresponding to the cosine value of the double angle of the phase difference (θe) is calculated by the following equation (34). it can.

  Then, from the sine cosine value (Vs ^) and the cosine reference value (Vc ^), for example, the phase difference (θe) is calculated by the following equation (35), and the actual value of the rotor angle (θ = θ ^ + θe) Can be calculated.

  Here, the matrix C is a function of the basic voltage string pattern, and since this component is constant, the component of the matrix D ^ in the above equation (34) can be calculated in advance. In addition, the coefficient s ′ (k) in the above equation (34) is expressed as the following equation (36). √ {(dHd (i)) 2+ (dHq (i)) 2} It can be calculated from the voltage string pattern data and the modulation coefficient.

  For this reason, the modulation coefficient {s based on the second-order difference (ddIdq ^) of the detected current calculated from the change amount of the detected current in each control cycle within the predetermined period, the d-axis feedback voltage, and the q-axis feedback voltage. The rotor angle of the brushless DC motor 1 can be calculated by a simple calculation process using the correction value {s ′ (k)} of (k)} and the components of the matrix D calculated in advance.

  In addition, by limiting the d-axis feedback voltage and the q-axis feedback voltage in this way, it is possible to suppress the occurrence of interference with the feedback control of the d-axis current and the q-axis current when the inspection voltage is superimposed. . For this reason, the process which applies a low-pass filter to a current feedback system, for example in order to suppress interference becomes unnecessary, and it can prevent that the responsiveness of rotor angle detection deteriorates when a low-pass filter is applied.

(Device configuration)
Next, the brushless DC motor control device 10 for controlling the brushless DC motor 1 will be described.
A brushless DC motor control device 10 (hereinafter simply referred to as a motor control device 10) according to this embodiment includes, for example, a brushless DC motor 1 (hereinafter simply referred to as a motor 1) mounted on a hybrid vehicle as a drive source together with an internal combustion engine. The motor 1 is directly connected in series with the internal combustion engine, and has a rotor 2 having a permanent magnet used for a field, and a three-phase that generates a rotating magnetic field that rotates the rotor 2. (U phase, V phase, W phase) armatures 3, 4 and 5 are provided.

  The motor control device 10 shown in FIG. 2 is a feedback circuit that feedback-controls the current flowing through the armatures 3, 4, 5 of the salient pole type motor 1 shown in FIG. This is converted into an equivalent circuit using a dq coordinate system having a q-axis armature on the q-axis that is the magnetic flux direction of the magnetic pole and a d-axis armature on the d-axis orthogonal to the q-axis.

  As a result, the motor control device 10 determines the current flowing through the d-axis armature (hereinafter referred to as the d-axis current) according to the d-axis command current (Id_c) and the q-axis command current (Iq_c) given from the control unit 11. ) And a current flowing through the q-axis armature (hereinafter referred to as a q-axis current).

  Specifically, the motor control device 10 determines the voltage applied to the d-axis armature (hereinafter referred to as d-axis voltage (Vd)) and the voltage applied to the q-axis armature (hereinafter referred to as q-axis voltage (Vq)). Dq-3 phase conversion for converting the drive voltage command voltages (Vu_c, Vv_c, Vw_c) applied to the three-phase armatures 3, 4, 5 of the U phase, V phase, and W phase of the motor 1 Unit 20, inspection voltage superimposing unit 21 for generating inspection voltages (Hd ^, Hq ^), and drive voltages (Vu, Vv, Vw) corresponding to command voltages (Vu_c, Vv_c, Vw_c) And a power drive unit (PDU) 22 configured by an inverter circuit in which a plurality of switching elements are bridge-connected so as to be applied to the armatures 3, 4 and 5 of the U-phase, V-phase, and W-phase, respectively.

Further, the motor control device 10 includes a U-phase current sensor 23 that detects a current flowing through the U-phase armature 3 of the motor 1 and a W-phase current sensor 24 that detects a current flowing through the W-phase armature 5 of the motor 1. The d-axis actual current (Id_s) and the q-axis current, which are detected values of the d-axis current, according to the detected current value (Iu_s) of the U-phase current sensor 23 and the detected current value (Iw_s) of the W-phase current sensor 24 Between the d-axis and the q-axis, the three-phase-dq converter 26 that calculates the q-axis actual current (Iq_s) that is the detected value of the motor, the angle detector 25 that detects the rotor angle (θ) of the motor 1, In order to cancel the velocity electromotive force components that interfere with each other and control the d-axis and the q-axis independently, a d-axis compensation term and a q-axis compensation term that cancel each interference component with respect to the d-axis and the q-axis are calculated. The non-interference calculation unit 27 and the temperature of the permanent magnet provided in the rotor 2 (magnet temperature ) Provided with a motor temperature detector 28 for detecting a TM, and a magnetic pole determination current command unit 29.
Further, the magnetic pole discriminating current command unit 29 includes, for example, a drive system selecting unit 41 and a magnetic pole discriminating current command value calculating unit 42 as shown in FIG.

  The motor control device 10 subtracts the d-axis actual current (Id_s) from the d-axis command current (Id_c) by the first calculator 31, and performs a PI (proportional integration) process on the subtraction result by the first PI calculator 32. Then, the first adder 33 adds the d-axis compensation term to generate a d-axis feedback voltage (Vd_fb) corresponding to the deviation between the d-axis command current (Id_c) and the d-axis actual current (Id_s). Similarly, the motor control device 10 subtracts the q-axis actual current (Iq_s) from the q-axis command current (Iq_c) by the second computing unit 34, and the second PI computing unit 35 subtracts the subtraction result from the PI calculation unit 35. The second adder 36 adds the q-axis compensation term to generate a q-axis feedback voltage (Vq_fb) corresponding to the deviation between the q-axis command current (Iq_c) and the q-axis actual current (Iq_s). .

  Then, the motor control device 10 uses the third adder 37 and the fourth adder 38 to check the test voltage (Hd ^) and the test for the d-axis feedback voltage (Vd_fb) and the q-axis feedback voltage (Vq_fb). The voltage (Hq ^) is added and input to the dq-3 phase converter 20 as a d-axis voltage (Vd) and a q-axis voltage (Vq). As a result, the deviation between the d-axis command current (Id_c) and the d-axis actual current (Id_s), and the q-axis command current (Iq_c) and the q-axis actual current ( Iq_s) is applied to the armatures 3, 4, 5 of the motor 1 to reduce the deviation from the current Iq_s), and each current flowing through the armatures 3, 4, 5 of the motor 1 is fed back. Be controlled.

  Here, when the dq-3 phase converter 20 converts the d-axis voltage (Vd) and the q-axis voltage (Vq) into three-phase voltage commands (Vu_c, Vv_c, Vw_c), the rotor angle of the motor 1 ( θ) is required. In the three-phase-dq converter 26, the detected current value (Iu_s) of the U-phase current sensor 23 and the detected current value (Iw_s) of the W-phase current sensor 24 are converted into the d-axis actual current (Id_s) and the q-axis actual current (Iq_s). ) Also requires the rotor angle (θ) of the motor 1.

  Therefore, the motor control device 10 superimposes the inspection voltage (Hd ^) on the d-axis voltage (Vd_fb) by the inspection voltage superimposing unit 21 in the third adder 37 without using a position detection sensor such as a resolver, Further, when the inspection voltage (Hq ^) is superimposed on the q-axis voltage (Vq_fb) by the inspection voltage superimposing unit 21 in the fourth adder 38, based on the estimated value (θ ^) of the rotor angle of the motor 1. The rotor angle (θ) of the motor 1 is detected using the d-axis actual current (Id_s ^) and the q-axis actual current (Iq_s ^) calculated by the three-phase-dq converter 26. Therefore, as described above, the dq-3 phase conversion unit 20 is supplied to the d-axis voltage (Vd) obtained by superimposing the test voltage (Hd ^) on the d-axis voltage (Vd_fb) and the q-axis voltage (Vq_fb). The q-axis voltage (Vq) on which the inspection voltage (Hq ^) is superimposed is input.

(Rotor angle detection process)
Next, details of the rotor angle (θ) detection process in the motor control device 10 will be described. The initial value of the estimated value (θ ^) of the rotor angle of the motor 1 is “0”.
First, as illustrated in FIG. 4A, the inspection voltage superimposing unit 21 performs the inspection voltage Hdq ^ (Hd ^, Hq) in which n periods of the control cycle (Δt) of the motor control device 10 are one period. ^) Is generated by the following equation (37).

  Where Hdq ^ (x) is the output level of the test voltage in the xth control cycle after the start of superimposition of the test voltage, and i is the time series number of the control cycle in one cycle of the test voltage (i = 1) , 2,..., N), k is the time series number of the cycle of the test voltage (k = 1, 2,...), And Hd ^ (x) is the xth control cycle after the superposition of the test voltage is started. The d-axis component of the output level of the inspection voltage at H, and Hq ^ (x) is the q-axis component of the output level of the inspection voltage in the xth control cycle after the start of superimposition of the inspection voltage, and s (k) is The value of the modulation signal (s) in the period of the time series number k (corresponding to the modulation coefficient), dhdq ^ (x) is the basic voltage string data in the xth control cycle after starting to superimpose the inspection voltage, dhd ^ (X) is the number x after superimposing the inspection voltage d-axis component of the fundamental voltage column data in the control cycle, and DHQ ^ (x) is q-axis component of the fundamental voltage column data in the x-th control cycle from the start of superimposition of the test voltage.

  The basic voltage string data [dhdq ^ = {dhdq ^ (1), dhdq ^ (2),..., Dhdq ^ (n)}] is stored in advance in a memory (not shown). Further, the data {s (1), s (2),...} Of the modulation signal (s) may be stored in a memory in advance, and generated using a technique such as an M-sequence that is often used in signal processing. May be. Further, the basic voltage string data [dhdq ^ = {dhdq ^ (1), dhdq ^ (2), ..., dhdq ^ (n)}] is an average in one period as shown in the following equation (38). Is set to 0.

  In this case, since the modulation signal (s) is changed for each cycle of the test voltage (Hdq ^) as shown in the above equation (37), one cycle (T) of the test voltage (Hdq ^). The average voltage level at “0” is “0”. As a result, the levels of the d-axis voltage (Vd) and the q-axis voltage (Vq) gradually increase, and the influence on the feedback control system of the armature current of the motor 1 is suppressed.

  Then, the angle detection unit 25 detects the motor 1 in each control cycle {t (1) to t (n)} when the inspection voltage (Hd ^, Hq ^) is superimposed by the inspection voltage superimposing unit 21. The rotor angle of the motor 1 is detected using the d-axis actual current and the q-axis actual current calculated by the three-phase-dq converter 26 based on the estimated value (θ ^) of the rotor angle.

  Here, the second-order difference of the d-axis actual current and the second-order difference of the q-axis actual current in the control cycle t (i) of the k-th control cycle T (k) of the test voltages (Hd ^, Hq ^) As shown in the following equation (39), it is assumed that “ddId ^ (i + k · n)” and “ddIq ^ (i + k · n)”, respectively.

  Further, the amount of change {dHd ^ (i + k · n), dHq (i + k · n)} in the control cycle t (i) of the k-th period T (k) of the test voltage (Hd ^, Hq ^) It is expressed by the following formulas (40) and (41) according to formula (37).

  The third adder 37 and the fourth adder 38 are the previous control cycle of the d-axis feedback voltage (Vd_fb) calculated by the above equation (26) by the first calculator 31 and the first PI calculator 35. The previous control cycle of the differential voltage (dVd_fb) with respect to the d-axis voltage (Vd) and the q-axis feedback voltage (Vq_fb) calculated by the above equation (27) by the second calculator 34 and the second PI calculator 35 The direction of the voltage vector whose component is the difference voltage (Vq_fb) with respect to the q-axis voltage (Vq) in the component is the difference voltage {dHd ^ (i + k · n), dHq ^ (i + k · n)} of the test voltage The d-axis voltage (Vd) and the q-axis voltage (Vq) calculated by the calculation of the following equations (42) and (43) And outputs it to the section 20.

  However, k1 is dHd ^ (i + k · n), k2 is dHd ^ (i + k · n) 1, Vd_old is the d-axis voltage in the previous control cycle, and Vq_old is the q-axis voltage in the previous control cycle.

  For this reason, the matrix c ^ (i + k · n) corresponding to the matrix c ^ (1) in the above equation (32) is expressed by the following equation (44).

  Then, in Ts {control cycle t (i) of the (k-1) th period T (k-1) to control cycle t (i) of the kth period T (k)} in FIG. Summarizing the equation (32), it can be expressed in the form of the following equation (45), and the equation (45) can be further modified to obtain the following equations (46) and (47).

  Here, FIG. 4B is a time series graph showing transition of the inspection voltage (Hdq) and the detected current (Idq) in the control cycles t (i−2) to t (i + 2). From the change amount {dIdq ^ (i)} of the detected current in the control cycle period t (i) and the change amount {dIdq ^ (i + 1)} of the detected current in the control cycle period t (i + 1), the detection in the above equation (39). The second-order difference {ddIdq ^ (i)} of the current can be calculated.

  On the other hand, the components of the matrix c ^ (i) in the above equation (44) calculated according to the basic voltage string data (dhdq ^) are constant. Therefore, the components of the matrix C ^ in the equation (46) are also constant, and the components of the matrix D ^ in the equation (47) calculated based on the matrix C are also constant. Therefore, the components of the matrix D ^ in the equation (47) can be calculated in advance from the basic voltage string data (dhdq ^). Therefore, the data of the matrix D ^ calculated in this way is stored in advance in the memory of the motor control apparatus 10, and the angle detection unit 25 stores the data of the matrix D ^ stored in the memory. The above equation (47) is calculated using.

  In this case, the angle detection unit 25 simply calculates the component of the matrix D ^, the second-order difference (ddIdq ^) of the detected current in each control period, and s' obtained by correcting the modulation signal (s) according to the above equation (31). A sine reference value (Vs ^ = L1sin2θe) and a cosine reference value (Vc) corresponding to a double angle of the phase difference (θe = θ−θ ^) between the actual value (θ) of the rotor angle and the estimated value (θ ^) by calculation. ^ = L1 cos 2θe) can be calculated. Therefore, the calculation time of the sine reference value (Vs ^) and the cosine reference value (Vc ^) can be shortened.

  Further, in this way, the direction of the voltage having the d-axis feedback voltage (Vd_fb) and the q-axis feedback voltage (Vq_fb) as components is represented by the amount of change in test voltage {dHd ^ (i + k · n), dHq ^ (i + k · n)} as a component, the current feedback need not be subjected to a low-pass filter in order to reduce interference with the current feedback system due to the superimposition of the inspection voltage. Therefore, the response of the current feedback system can be maintained well.

  Then, the angle detector 25 calculates the phase difference (θe) between the actual value (θ) of the rotor angle of the motor 1 and the estimated value (θ ^) by the following equation (48), and the rotor angle (θ = θ ^ + θe) is detected.

  In addition, the estimated value (θ ^) of the rotor angle is corrected so that the estimated error (θe) converges to 0 by the follow-up calculation of the observer by the following equation (49) or (50), and the rotor angle is It can also be detected.

  Further, by changing the offset value in the above equations (49) and (50), the phase of the detected rotor angle can be forcibly shifted to reduce the detection error.

  In addition, when the time required for the calculation of √ (Vs ^ 2 + Vc ^ 2) in the above equation (50) increases, it may be approximated by the following equation (51).

  In the present embodiment, the inspection voltage superimposing unit 21 uses the basic voltage string data {dhdq ^ to the inspection voltage {Hdq (i−1 + k · n)} in the previous control cycle according to the above equation (37). (I-1)} and the modulation signal {s (k)} are added to calculate the test voltage {Hdq ^ (i + k · n)} in the current control cycle. When the value of s (k} is set, since the basic voltage string data is also known, the inspection voltage (Hdq ^) can be calculated in advance.

  In this case, the d-axis voltage (Vd) and the q-axis voltage (Vq) can be calculated by the following equations (52) and (53).

  Then, according to the following formulas (54) and (55), the differential voltage (Vd (i + k · n) −Vd_old) of the d-axis voltage and the q-axis voltage of the current control cycle with respect to the previous control cycle (Vq) The direction of the voltage vector having (i + k · n) −Vq_old) as a component can be limited to the direction of the differential voltage (k1, k2) of the current test voltage with respect to the previous control cycle.

  However, Vd_old is a d-axis voltage in the previous control cycle, and Vq_old is a q-axis voltage in the previous control cycle. Therefore, in this case, the third adder 37 and the fourth adder 38 calculate the d-axis voltage (Vd) and the q-axis voltage (Vq) by the following equation (56), and obtain the current feedback result. It can restrict | limit to the direction of the differential voltage (k1, k2) of the voltage for a test | inspection.

(Magnetic pole discrimination processing)
Furthermore, since the inductance fluctuation accompanying the rotation of the rotor 2 is a half cycle of the rotor angle (θ), the calculated value of the rotor angle (θ) calculated by the above-described process is an electrical angle of 0 to 180 [degrees], Or it becomes the same value in both regions of electrical angles 180 to 360 [degrees]. Therefore, in order to detect the initial rotor angle (θ) in the electric angle range of 0 to 360 [degrees] when the motor 1 is started, the magnetic pole discrimination process for discriminating the direction of the magnetic pole of the rotor 2 is executed, and the rotor angle ( It is necessary to determine whether the calculated value of θ) is a value in an electrical angle range of 0 to 180 [degrees] or an electrical angle of 180 to 360 [degrees].

For example, if the rotor 2 is fixed at a certain position and a current is passed through the q-axis armature at this time to generate a magnetic field in the q-axis direction (the magnetic flux direction of the magnet of the rotor 2), the following two events will occur. Occurrence is considered.
(1) In the case of “the direction of the magnetic field generated by the current = the direction of the magnetic field generated by the magnet”, since the magnetic field is saturated, the variation of the self-inductance DC component l of each phase of the U phase, V phase, and W phase Δl increases.
(2) In the case of “the direction of the magnetic field generated by the current ≠ the direction of the magnetic field generated by the magnet”, since the magnetic field is in an unsaturated state, fluctuations in the self-inductance DC component l of each phase of the U phase, V phase, and W phase The minute Δl becomes smaller.

This phenomenon occurs when the rotor 2 is fixed at a certain position, and currents in the positive and negative directions are supplied to the q-axis armature to generate a magnetic field in the q-axis direction (the magnetic flux direction of the magnet of the rotor 2). Is the same,
(1) In the case of “the direction of the magnetic field generated by the positive current = the direction of the magnetic field generated by the magnet”, since the magnetic field is saturated, the self-inductance DC component l of each phase of the U phase, V phase, and W phase The variation Δl increases.
(2) In the case of “the direction of the magnetic field generated by the negative direction current ≠ the direction of the magnetic field generated by the magnet”, since the magnetic field is in an unsaturated state, the self-inductance DC component l of each phase of the U phase, V phase, and W phase The fluctuation amount Δl of becomes smaller.

  Therefore, the cosine reference value (Vc ^) calculated by the above-described equation (34) that changes depending on the value of the variation Δl of the self-inductance DC component l of each phase of the U phase, the V phase, and the W phase is the positive direction current. Is calculated from each of Δl based on the current and Δl based on the negative direction current, and the magnitudes are compared, so that the rotor 2 can be in either the electrical angle 0 to 180 [degrees] or the electrical angle 180 to 360 [degrees] region. It can be determined whether it exists.

  Specifically, for example, if the cosine reference value (Vc ^) calculated from the Δl value based on the positive current is Vc1, and the cosine reference value (Vc ^) calculated based on the Δl value based on the negative current is Vc2, When the magnetic pole discrimination calculation result “A = Vc1−Vc2” is defined, depending on whether the magnetic pole discrimination calculation result A is positive or negative, the rotor 2 has either an electrical angle of 0 to 180 degrees or an electrical angle of 180 to 360 degrees. Can be determined. For example, as shown in FIG. 5, whether the actual rotor angle (θ) = 75 [degrees] or the actual rotor angle (θ) = 255 [degrees], both of the rotor angles (θ) Since the calculated value is calculated to be 75 [degrees], depending on whether the magnetic pole discrimination calculation result A is positive or negative, for example, when the magnetic pole discrimination calculation result A is negative, the rotor angle (θ) = 75 [degrees], for example, the magnetic pole discrimination calculation result A Is positive, it is determined that the rotor angle (θ) = 255 [degrees].

  The magnetic pole discriminating current command unit 29 outputs a magnetic pole discriminating current command for the current supplied to the q-axis armature to generate a magnetic field in the q-axis direction (the magnetic flux direction of the magnet of the rotor 2) in the magnetic pole discrimination process described above. At the time of starting the internal combustion engine at the time of starting the vehicle with the ignition switch set to the on state or returning from the idling stop state, etc. The necessity of execution of the magnetic pole discrimination process and the driving method of the internal combustion engine are set according to the magnet temperature TM.

  For example, when the magnet temperature TM is in a high temperature state where the magnet temperature TM is equal to or higher than the predetermined first threshold temperature T1, the drive method selection unit 41 of the magnetic pole discrimination current command unit 29 is configured to start the vehicle with the ignition switch set to the on state. Alternatively, at the time of starting the internal combustion engine, such as when the vehicle is returned from the idle stop state, execution of the magnetic pole discrimination processing is prohibited, and each armature 3, 4, regardless of the forced commutation, that is, the magnetic pole position of the rotor 2. The starter drive command for instructing to start the internal combustion engine is started to the control unit 11 by starting the motor 1 by sequentially commutating the energization to 5 or by another starting device 9 mounted on the vehicle. Output.

On the other hand, when the magnet temperature TM is lower than the predetermined first threshold temperature T1, the drive method selection unit 41 instructs execution of the magnetic pole discrimination process, and also detects the direction of the magnetic pole of the rotor 2 and the rotor angle ( In response to θ), a drive command for driving the motor 1 is output to the magnetic pole discrimination current command value calculation unit 42.
The magnetic pole discriminating current command value calculation unit 42 sets a magnetic pole discriminating current command for the current supplied to the q-axis armature in the magnetic pole discriminating process according to the magnet temperature TM. For example, the magnet temperature TM is a predetermined first threshold value. When the temperature is equal to or higher than a predetermined second threshold temperature T2 lower than the temperature T1, the q-axis command current (Iq_c) is set to increase the field axis current as the magnet temperature TM increases. A predetermined correction current command value I1 to be added is set, and this correction current command value I1 is output to the second calculator 34 as a magnetic pole discrimination current command. Thereby, in the second calculator 34, a value (Iq_c + I1) obtained by adding the correction current command value I1 to the q-axis command current Iq_c is newly set as the q-axis command current Iq_c.
On the other hand, when the magnet temperature TM is lower than the predetermined second threshold temperature T2 lower than the predetermined first threshold temperature T1, the magnetic pole discrimination current command value calculation unit 42 sets the correction current command value I1 to zero, 2 The calculator 34 is set so that the q-axis command current Iq_c input from the control unit 11 is not corrected.

In a series of processes executed at the time of starting the motor 1 such as at the time of starting the vehicle with the ignition switch set to the on state or returning from the idling stop state of the vehicle, first, the initial rotor angle (θ) Is detected by the angle detector 25 and set as an initial position candidate of the rotor 2.
Next, a field axis voltage (that is, an inspection voltage (Hq ^)) for sequentially generating a magnetic field along each direction toward one and the other in the field axis direction corresponding to the set initial position candidate is inspected. Applied to the q-axis armature by the voltage superimposing unit 21 (that is, added to the q-axis feedback voltage (Vq_fb)).

Then, the rotor angle (θ) is detected by the angle detection unit 25, and the cosine reference value (Vc ^) = Vc1, which is calculated from the Δl value based on the positive current calculated based on the formula (34). And, based on the cosine reference value (Vc ^) = Vc2 calculated by the Δl value based on the negative direction current, the magnetic pole discrimination calculation result “A = Vc1−Vc2” is calculated. It is detected whether the direction of the magnetic pole of the rotor 2 corresponds to a value in an electrical angle of 0 to 180 [degrees] or an electrical angle of 180 to 360 [degrees].
A drive command for driving the motor 1 according to the detected direction of the magnetic pole and the rotor angle (θ) detected by the angle detection unit 25 at this time is a d-axis command current (Id_c) and a q-axis command. It is output from the control unit 11 as a current (Iq_c).

  The motor control device 10 according to the above-described embodiment has the above-described configuration. Next, the operation of the motor control device 10, particularly from the start of the vehicle in which the ignition switch is set to the on state or from the idle stop state of the vehicle. An internal combustion engine start process executed at the time of returning will be described with reference to the accompanying drawings.

First, in step S01 shown in FIG. 6, it is determined whether or not the magnet temperature TM is lower than a predetermined first threshold temperature T1.
If this determination is “YES”, the flow proceeds to step S 03 described later.
On the other hand, if this determination is “NO”, the flow proceeds to step S 02.
In step S02, it is determined that there is a risk that the permanent magnet may be demagnetized when the permanent magnet of the rotor is in a high temperature state and the magnetic pole determination process is executed, and the execution of the magnetic pole determination process is prohibited. Regardless of the forced commutation, that is, the magnetic pole position of the rotor 2, the motor 1 is started by sequentially commutating the energization to the armatures 3, 4, 5, or other starter mounted on the vehicle. In step 9, the internal combustion engine is started, and a series of processing ends.

In step S03, as the magnetic pole discrimination processing, the initial position candidate (that is, the initial rotor angle (θ) detected by the angle detection unit 25) is set in each direction toward one and the other in the field axis direction. A field axis voltage (that is, a test voltage (Hq ^)) for generating a magnetic field sequentially is applied to the q-axis armature (that is, added to the q-axis feedback voltage (Vq_fb)).
In step S04, it is determined whether or not the magnet temperature TM is lower than a predetermined second threshold temperature T2 that is lower than a predetermined first threshold temperature T1.
If this determination is “NO”, the flow proceeds to step S 06 described later.
On the other hand, if this determination is “YES”, the flow proceeds to step S 05.

In step S05, the process proceeds to step S07 without changing the q-axis command current (Iq_c) output from the control unit 11.
In step S06, a value (Iq_c + I1) obtained by adding a predetermined correction current command value I1 to the q-axis command current Iq_c output from the control unit 11 is newly set as a q-axis command current Iq_c. Proceed to step S07.

In step S07, the rotor angle (θ) is detected by the angle detection unit 25, and the cosine reference value (Vc) calculated based on the Δl value based on the positive current calculated based on the formula (34). ^) = Vc1 and the magnetic pole discrimination calculation result “A = Vc1−Vc2” is calculated based on the cosine reference value (Vc ^) = Vc2 calculated by the Δl value based on the negative current, and this magnetic pole discrimination calculation result Based on the sign of A, it is detected whether the direction of the magnetic pole of the rotor 2 corresponds to a value in an electrical angle range of 0 to 180 [degrees] or an electrical angle of 180 to 360 [degrees].
In step S08, a drive command for driving the motor 1 is output according to the rotor angle (θ) and the magnetic pole direction, the motor 1 is started, and the internal combustion engine is started by the driving force of the motor 1. To end the series of processing.

As described above, according to the control apparatus 10 for the brushless DC motor according to the present embodiment, the magnetic pole discrimination current command unit 29 increases the field axis current as the magnet temperature TM of the rotor 2 increases. Therefore, even when the magnetic flux density of the permanent magnet changes to a decreasing tendency as the magnet temperature TM of the rotor 2 increases, the determination accuracy of the magnetic pole determination process is prevented from decreasing. be able to.
Further, when starting the internal combustion engine at the time of starting the vehicle with the ignition switch set to the on state or returning from the idling stop state of the vehicle, the magnetic pole discriminating current command unit 29 has the magnet temperature TM set to a predetermined value. When the temperature exceeds one threshold temperature T1, execution of the magnetic pole discrimination processing is prohibited, and energization to each armature 3, 4, 5 is sequentially commutated regardless of forced commutation, that is, the magnetic pole position of the rotor 2. Thus, the motor 1 is started, or the internal combustion engine is started by another starting device 9 mounted on the vehicle, so that the field current for magnetic pole discrimination is applied to the armatures 3, 4, 5. The permanent magnet of the rotor 2 is excessively demagnetized because the current supplied to the armatures 3, 4, and 5 exceeds the upper limit current within a predetermined allowable range for the motor 1 in a relatively high temperature state. Will be While preventing the door, it is possible to start the internal combustion engine accurately.

In the above-described embodiment, the magnet temperature TM detected by the motor temperature detection unit 28 is input to the magnetic pole discrimination current command unit 29. However, the present invention is not limited to this. For example, the magnetic pole discrimination current command unit 29 The magnet temperature TM may be estimated.
In the first modification of the above-described embodiment, the magnetic pole discriminating current command unit 29 is, for example, as shown in FIG. 7, the vehicle state detected by the vehicle state sensor 51, for example, the engine water temperature, the engine oil temperature, each electric machine A temperature estimation unit 52 for estimating the magnet temperature TM by an appropriate estimation process based on each detected value such as the coil temperature of the children 3, 4, 5, the motor rotation speed NM, the induced voltage, and the time information output from the timer 53; The drive system selection unit 41 and the magnetic pole discrimination current command value calculation unit 42 are configured.

In the above-described embodiment, the magnetic pole discrimination current command value calculation unit 42 determines that the magnet temperature TM is equal to or higher than the predetermined second threshold temperature T2 that is lower than the predetermined first threshold temperature T1. The predetermined correction current command value I1 added to the q-axis command current (Iq_c) is set so that the field axis current increases as TM increases. However, the present invention is not limited to this, and the magnet temperature It may be set so that the field axis current changes in an increasing trend as TM increases.
In the second modification of the above-described embodiment, for example, as shown in FIG. 8, when the determination result of step S04 in the above-described embodiment is “NO”, the process proceeds to step S11. In S11, a correction current command value I1 that changes according to the magnet temperature TM is calculated by map search for a predetermined map set in advance or by calculation using a predetermined arithmetic expression, and the process proceeds to step S06. In the predetermined map or the predetermined arithmetic expression set in advance, the correction current command value I1 is set to change in an increasing tendency as the magnet temperature TM increases.

It is a figure which shows the block diagram and equivalent circuit of the brushless DC motor which concern on embodiment of this invention. It is a block diagram of the control apparatus of the brushless DC motor which concerns on embodiment of this invention. It is a block diagram of the magnetic pole discrimination | determination electric current instruction | command part shown in FIG. It is the figure which showed transition of the period of the voltage for an inspection, the voltage for an inspection, and dq axis current in the control device of the brushless DC motor concerning the embodiment of the present invention. It is the figure which showed the relationship between the positive / negative of the magnetic pole discrimination | determination calculation result A calculated in the control apparatus of the brushless DC motor which concerns on embodiment of this invention, and the calculated value of rotor angle ((theta)). It is a flowchart which shows operation | movement of the control apparatus of the brushless DC motor which concerns on embodiment of this invention, especially an internal combustion engine starting process. It is a block diagram of the magnetic pole discrimination | determination electric current instruction | command part which concerns on the 1st modification of embodiment of this invention. It is a flowchart which shows operation | movement of the control apparatus of the brushless DC motor which concerns on the 2nd modification of embodiment of this invention, especially an internal combustion engine starting process.

Explanation of symbols

1 Brushless DC motor 2 Rotor 3, 4, 5 Armature (stator winding)
10 Brushless DC motor control device 25 Angle detection unit (position detection means, magnetic pole discrimination means)
29 Magnetic pole discrimination current command section (Magnetic pole discrimination current changing means)
Step S02 Starting means, starting means Step S06 Magnetic pole discrimination current changing means

Claims (3)

Brushless DC motor control device comprising position detecting means for applying a harmonic voltage to a stator winding of a brushless DC motor having a permanent magnet rotor and detecting the position of the rotor from a motor current generated by the high frequency voltage Because
Magnetic pole determining means for applying a magnetic pole detection voltage corresponding to the magnetic field direction of the rotor to the stator winding to determine the direction of the magnetic pole of the rotor;
Magnetic pole discrimination current changing means for increasing the field axis current as the magnet temperature of the rotor increases during execution of the magnetic pole discrimination processing by the magnetic pole discrimination means ;
Starting means for prohibiting execution of magnetic pole discrimination processing by the magnetic pole discrimination means when the magnet temperature exceeds a predetermined threshold temperature, and starting the brushless DC motor by forced commutation ;
The magnetic pole discriminating current changing means increases the field axis current when the magnet temperature is equal to or higher than a second threshold temperature lower than the predetermined threshold temperature,
The control of the brushless DC motor, wherein the predetermined threshold temperature is a magnet temperature corresponding to a case where the magnet of the rotor is demagnetized by a current supplied to the stator winding when the magnetic pole discrimination process is executed. apparatus. The rotor is connected to a drive shaft of a vehicle and a crankshaft of an internal combustion engine; the brushless DC motor is capable of driving the vehicle and starting the internal combustion engine;
The magnetic pole discriminating current changing means performs a magnetic pole discriminating process by the magnetic pole discriminating means when starting the brushless DC motor and starting the internal combustion engine by the brushless DC motor when the magnet temperature is lower than a predetermined threshold temperature. 2. The brushless DC motor control device according to claim 1 , wherein at the time of execution, the field axis current is set to increase as the magnet temperature of the rotor increases . 3. The brushless DC motor control device according to claim 2 , further comprising start means for starting the internal combustion engine by a start device mounted on a vehicle when the magnet temperature exceeds a predetermined threshold temperature .

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