JP2009273251A - Motor drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensorless motor drive circuit that can be applied to a brushless motor of delta connection, in which there is no neutral potential. <P>SOLUTION: U and V phases are GND-connected, and a W phase is not connected. Voltages Vn1 and Vn2 are detected. The U phase is plus potential-connected, the V phase is GND-connected and the W phase is not connected. Voltages Vn1' and Vn2' are detected. The ratio between impedance of the U phase and impedance of the V phase is obtained. The V and W phases are GND-connected and the U phase is not connected. Voltages Vn3 and Vn4 are detected. The V phase is plus potential-connected, the W phase is GND-connected and the U phase is not connected. Voltages Vn3' and Vn4' are detected and the ratio between impedance of the V phase and impedance of the W phase is obtained. Thus, the impedance ratios for the respective phases are obtained. The relative angle of three phase armature winding and a magnet rotor is derived from the obtained impedance ratio. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor drive device, and more particularly to a motor drive device that drives a motor such as a brushless motor.

  In a motor such as a brushless motor, it is generally necessary to detect the position of the rotor, and the position of the rotor is detected using a magnetic sensor such as a Hall element. However, by providing the sensor, it is easy to be restricted by the use environment of the sensor, the wiring of the motor is increased, and various adverse effects may occur from the viewpoint of the motor space and the number of parts.

  Therefore, a technique for driving and controlling a motor without providing a sensor such as a Hall element has been proposed. For example, in the technique described in Patent Document 1, it is proposed to obtain the inductance between different phases by using the difference in inductance between the phases depending on the angle of the rotor, and obtain the electrical angle from the relationship stored in advance. ing. Specifically, it has been proposed to detect the position of the rotor in a stopped state using a current detector.

  However, since the technique described in Patent Document 1 requires a current detector separately, the techniques described in Patent Document 2 and Patent Document 3 have been developed.

  In the technique described in Patent Document 2, a power source voltage is applied to a field winding to calculate a rotor angle from a voltage induced in each phase, and based on the calculated rotor angle, an armature winding is calculated. The power is turned on. It has also been proposed to control the armature without using a magnetic pole position sensor by estimating the time from the initial angle estimated value to the next energized phase switching and switching the energized phase.

Further, in the technique described in Patent Document 3, it is proposed to measure a neutral point potential when a pulse voltage is applied to a motor and to examine an inductance value to obtain a total rotation angle.
Japanese Patent Laid-Open No. 7-177788 JP 2005-12952 A Special table 2001-516198 gazette

  However, in any of the techniques of Patent Documents 2 and 3, it is necessary to take out a neutral point, which cannot be realized by delta connection.

  The present invention has been made in consideration of the above-described facts, and an object of the present invention is to provide a sensorless motor driving circuit that can be applied to a delta-connected brushless motor having no neutral potential.

  In order to achieve the above object, the invention described in claim 1 is based on a motor that rotates a rotor by sequentially applying electric power to armature windings of three or more phases and a plurality of switching elements. A switching element group for converting DC power into AC power and applying it to the motor, a control means for controlling the switching element group for controlling rotation of the rotor, and a degree that the rotor does not rotate The control means detects the terminal voltage of the armature winding when the control means controls the switching element group so as to apply the power of the motor to the motor, and based on the detection result, the rotor of the rotor with respect to the armature winding And a derivation means for deriving the relative angle.

  According to the first aspect of the present invention, the motor rotates the rotor by sequentially applying electric power to the armature windings of the three or more phases and the switching element group turns the plurality of switching elements on and off. By doing so, DC power is converted to AC power and applied to the motor.

  And in a control means, in order to control rotation of a rotor, a switching element group is controlled, and a motor is driven by this.

  By the way, in a motor having a multi-phase armature winding, in order to drive the motor, it is necessary to detect the relative angle of the rotor with respect to the armature winding. On the other hand, since the inductance of the armature winding of each phase changes according to the relative angle of the rotor with respect to the armature winding, the impedance of each phase changes between the armature winding and the rotor.

  Therefore, the deriving unit detects the terminal voltage of the armature winding when the control unit controls the switching element group so that the electric power that does not rotate the rotor is applied to the motor. Then, a relative angle of the rotor with respect to the armature winding is derived based on the detected terminal voltage. This makes it possible to drive and control the motor.

  In other words, since the terminal voltage is detected when power that does not allow the rotor to rotate is applied to the armature winding, it is not necessary to take out the neutral point potential. Therefore, the present invention can be applied to both star connection and delta connection. Therefore, it is possible to provide a sensorless motor drive circuit that can be applied to a delta-connected brushless motor that does not have a neutral potential.

  According to a second aspect of the present invention, in the first aspect of the invention, the derivation means obtains an impedance ratio of each phase from the terminal voltage of the armature winding, and the relative angle of the rotor is determined from the impedance ratio. It is characterized by deriving.

  According to the invention described in claim 2, as described above, since the impedance of the armature winding of each phase changes according to the relative angle of the rotor with respect to the armature winding, the derivation means includes the armature winding. By obtaining the impedance ratio of each phase from the terminal voltage of the wire, the relative angle of the rotor can be derived from the obtained impedance ratio using a known technique.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the derivation means detects a terminal voltage of the armature winding to which no power is applied, and determines the relative angle. It is characterized by deriving.

  According to the third aspect of the present invention, the derivation means can determine the impedance ratio of each phase by detecting the terminal voltage of the armature winding to which no electric power is applied, and the electric impedance can be obtained from the impedance ratio. It is possible to derive the relative angle of the rotor with respect to the child winding.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, in the first aspect, the derivation unit causes the control unit to disconnect one of the terminals of the armature winding, and the remaining terminals have a negative potential. And one terminal among the terminals of the armature winding is connected to a positive potential by the control means, and a potential based on a terminal voltage that is not connected when controlled to be connected to the other terminal. The armature winding is compared with a potential based on a terminal voltage that is not connected when one terminal is connected to a negative potential and the remaining terminals are controlled to be disconnected. The ratio of the alternating current impedance component is obtained, and the relative angle is derived from the obtained ratio.

  According to the invention described in claim 4, the derivation means is configured so that the switching element group is controlled by the control means so that one of the terminals of the armature winding is not connected and the remaining terminals are connected to a negative potential. One of the terminals of the armature winding is connected to the positive potential, and one of the remaining terminals is connected to the negative potential, and the rest is based on the terminal voltage that is not connected when controlled. The ratio of the impedance AC component of the armature winding is compared with the potential based on the terminal voltage that is not connected when the switching element group is controlled by the control means so that the terminals of the armature winding are not connected. And the relative angle of the rotor to the armature winding can be derived from the impedance ratio.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the derivation unit is configured such that one terminal of the terminals of the armature winding is disconnected by the control unit, and the remaining terminals are positive potentials. A potential based on a terminal voltage that is not connected when being controlled to be connected to the terminal, and one terminal among the terminals of the armature winding is connected to a positive potential by the control means, and the remaining terminals Of the armature winding is compared with a potential based on a terminal voltage that is not connected when one terminal is connected to a negative potential and the remaining terminals are controlled to be disconnected. It is characterized in that a ratio of impedance alternating current components of the line is obtained, and the relative angle is derived from the obtained ratio.

  According to the fifth aspect of the present invention, the derivation means is configured so that the switching element group is controlled by the control means so that one of the terminals of the armature winding is not connected and the remaining terminals are connected to a positive potential. One of the terminals of the armature winding is connected to the positive potential, and one of the remaining terminals is connected to the negative potential, and the rest is based on the terminal voltage that is not connected when controlled. The ratio of the impedance AC component of the armature winding is compared with the potential based on the terminal voltage that is not connected when the switching element group is controlled by the control means so that the terminals of the armature winding are not connected. And the relative angle of the rotor to the armature winding can be derived from the impedance ratio.

  The invention according to claim 6 is the invention according to claim 4 or 5, wherein the derivation means subtracts the induced voltage of the armature winding due to the magnetic flux of the rotor to obtain the ratio of the impedance AC component. It is characterized by seeking.

  According to the sixth aspect of the present invention, since the induced voltage is generated in the armature winding of each phase by the rotation of the rotor, the derivation means generates the induced voltage of the armature winding by the magnetic flux of the rotor. By subtracting and obtaining the ratio of the impedance alternating current component, the ratio of the impedance alternating current component excluding the induced voltage can be obtained.

  According to a seventh aspect of the present invention, in the invention according to the fourth or fifth aspect, the derivation means has a period in which the terminal voltage of the armature winding to be detected is detectable less than a voltage sampling period. The terminal voltage of the armature winding is adjusted by adjusting the connection period to the positive potential or the connection period to the negative potential until the generation period of the terminal voltage of the armature winding becomes larger than the voltage sampling period. It is characterized by performing detection.

  According to the seventh aspect of the present invention, when the period in which the terminal voltage of the armature winding to be detected is detectable is smaller than the voltage sampling period, the ratio of the impedance alternating current component of each phase cannot be obtained. Therefore, the derivation means adjusts the connection period to the positive potential or the connection period to the negative potential until the generation period of the terminal voltage of the armature winding becomes larger than the voltage sampling period, so that the terminal of the armature winding The voltage can be detected.

  According to an eighth aspect of the present invention, in the invention according to the fourth or fifth aspect, the derivation means includes: a positive side potential of a terminal of the armature winding that is not connected; a ground side potential; The impedance AC cost is obtained by comparing the potential difference between the two.

  According to the eighth aspect of the present invention, delta connection can be applied to the connection of the armature winding, and the motor can be driven without a sensor even in the delta connection.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a brushless motor driving apparatus according to an embodiment of the present invention.

  The brushless motor 12 includes a three-phase armature winding and a rotor in which U-phase, V-phase, and W-phase armature windings are star-connected (Y-connected). Each phase U, V, W of the three-phase armature winding is arranged at a pitch of 120 °, and the output of the switching element group 14 constituting the PWM (Pulse Width Modulation) type inverter of the brushless motor driving device 10 Connected with the end.

  The switching element group 14 is connected to a DC power source 16 and a capacitor C is connected in parallel. The three-phase armature winding is energized and switched to each phase of the three-phase armature winding by a transistor of the switching element group 14 at a predetermined timing, thereby forming a rotating magnetic field.

  Three pairs (six in total) of transistors TR1 to TR6 as switching elements constituting the switching element group 14 are connected in a three-phase bridge, and a diode D is connected in parallel to each transistor.

  Further, the brushless motor driving apparatus 10 is provided with a controller 18 for controlling the driving of the brushless motor 12 and an observer 20 for detecting the position of the rotor of the brushless motor 12.

  The controller 18 is connected to each transistor connected in a three-phase bridge, and is also connected to an observer 20. The position of the rotor of the brushless motor 12 detected by the observer 20 (the rotor position relative to the armature winding) is connected. The driving of the brushless motor 12 is controlled by controlling each transistor in accordance with the relative angle.

  The observer 20 is connected to the armature windings (terminals A to C) of each phase of the brushless motor 12, and detects the terminal voltage of the armature windings to detect the rotor with respect to the three-phase armature windings. The relative angle is detected, and the detection result is output to the controller 18. Specifically, the observer 20 includes a comparator that samples and holds the terminal voltage of the armature winding and compares the terminal voltage that has been separately sampled and held. A method for detecting the relative angle of the rotor with respect to the three-phase armature winding by the observer 20 will be described later.

  By the way, since the brushless motor switches energization to each phase of the three-phase armature winding in synchronization with the magnetic pole position of the rotor, it is necessary to detect the position of the rotor. In this embodiment, when detecting the position of the rotor, the relative angle between the three-phase armature winding and the rotor without using a sensor such as a Hall sensor is used. To detect.

  Here, a method for detecting the relative angle between the three-phase armature winding and the rotor in the brushless motor driving apparatus 10 according to the embodiment of the present invention will be described.

  The brushless motor 12 has an inductance that varies depending on the relative angle between the three-phase armature winding and the rotor, and has a salient pole ratio (ratio between the maximum value and the minimum value of inductance). As shown in FIG. 2A, the inductance change period varies depending on the N pole and S pole of the rotor, and is generated in two periods in the motor electrical angle 360 degree section. The inductance waveform of the three-phase brushless motor 12 is such that the U, V, and W phases are arranged with an electrical angle shifted by 120 degrees. Therefore, as shown in FIG. It becomes a certain waveform. That is, since the impedance value of the winding for each phase differs according to the relative angle between the three-phase armature winding and the rotor, the neutral potential waveform varies depending on which line the voltage is applied to.

  Therefore, in this embodiment, the impedance ratio of each phase is obtained from the impedance change caused by the inductance change of each phase.

  For example, by turning on the transistors TR1 and TR4 by the controller 18, the brass voltage of the DC power supply 16 is applied to the U-phase armature winding (terminal A) as shown in FIG. The armature winding (terminal B) is GND-connected, and the W-phase armature winding (terminal C) is not connected. When the potential difference at the terminal C of the W-phase armature winding is observed from the plus potential in this state, a voltage of Vn1 '= plus voltage × U phase impedance / (U phase impedance + V phase impedance) is generated. Further, when the potential difference between the GND and the terminal C of the W-phase armature winding is observed, a voltage of Vn2 ′ = plus voltage × V-phase impedance / (U-phase impedance + V-phase impedance) is generated. That is, when the observer 20 detects the voltage Vn1 'and the voltage Vn2', the ratio between the impedance of the U-phase armature winding and the impedance of the V-phase armature winding can be obtained. At this time, in order to extract only the voltage change excluding the change in the induced voltage of the armature winding, by turning on the transistors TR2 and TR4 by the controller 18, as shown in FIG. The phase and V-phase armature windings (terminals A and B) are GND-connected, and the W-phase armature winding (terminal C) is not connected. Then, the voltages Vn1 and Vn2 are detected, respectively, and the voltages Vn1 and Vn'2 are subtracted from the voltages Vn'1 and Vn'2, respectively, to obtain a ratio. As a result, as shown in the equation (1), the ratio between the impedance (AC component) of the U-phase armature winding and the impedance (AC component) of the V-phase armature winding can be obtained.

(Vn′1-Vn1): (Vn′2-Vn2) ≈Zu_AC component: Zv_AC component
... (1)

Similarly, by turning on the transistors TR3 and TR6 by the controller 18, as shown in FIG. 3D, a positive voltage of the power supply voltage is applied to the V-phase armature winding (terminal B), and the W-phase The armature windings (terminal C) are GND-connected and the U-phase armature windings are not connected. When the potential difference at the terminal A of the U-phase armature winding is observed from the plus potential in this state, a voltage of Vn3 ′ = plus voltage × V phase impedance / (V phase impedance + W phase impedance) is generated. When the potential difference between the GND and the terminal A of the U-phase armature winding is observed, a voltage of Vn4 ′ = plus voltage × W-phase impedance / (V-phase impedance + W-phase impedance) is generated. Then, in order to extract only the voltage change excluding the change in the induced voltage of the V-phase and W-phase armature windings, the controller 18 turns on the transistors TR4 and TR6, so that FIG. As shown, the V-phase and W-phase armature windings (terminals B and C) are GND-connected, and the U-phase armature winding (terminal A) is not connected. Then, the voltages Vn3 and Vn4 are detected, respectively, and the voltages Vn1 and Vn2 are subtracted from the voltages Vn′3 and Vn′4 to obtain the ratio, thereby obtaining the V-phase armature winding as shown in the equation (2). The ratio between the impedance (AC component) and the impedance (AC component) of the W-phase armature winding can be obtained.

(Vn′3-Vn3): (Vn′4-Vn4) ≈Zv_AC component: Zw_AC component
... (2)

Therefore, from the equations (1) and (2), the impedance of the U-phase armature winding (AC component), the impedance of the V-phase armature winding (AC component), and the impedance of the W-phase armature winding (AC component) The ratio can be obtained.

  The relative angle between the three-phase armature winding and the rotor can be derived from the impedance ratio of each phase by using a known technique.

  In the present embodiment, the controller 18 and the observer 20 perform the above operation in a carrier cycle, so that the relative angle between the three-phase armature winding and the rotor can be detected without a sensor in the carrier cycle.

  Next, a specific processing flow performed in the carrier cycle by the controller 18 and the observer 20 using the above-described method for detecting the relative angle between the three-phase armature winding and the rotor will be described. In the following, similar to the above example, the case where the W-phase armature winding is not connected and the case where the U-phase armature winding is not connected will be described by way of example. The armature winding to be made is not limited to the U phase and the W phase.

  First, by turning on the transistors TR2 and TR4 so that the controller 18 applies power to the brushless motor 12 so that the rotor does not rotate, the U-phase and V-phase armature windings (terminals A and B) are connected to GND. The connection and the W-phase armature winding (terminal C) are not connected (FIG. 3A), and after the observer 20 detects the voltages Vn1 and Vn2, the controller 18 supplies power to the extent that the rotor does not rotate. By turning on the transistors TR1 and TR4 so as to be applied to 12, the U-phase armature winding (terminal A) is connected to the positive potential, the V-phase armature winding (terminal B) is connected to GND, and the W-phase armature winding The line (terminal C) is disconnected, and the observer 20 detects the voltages Vn1 ′ and Vn2 ′ (FIG. 3B).

  That is, by switching from the state of FIG. 3 (A) to the state of FIG. 3 (B), a voltage is easily generated, and this is detected by the observer 20, and as described above, the U-phase armature winding The observer 20 can determine the ratio of the impedance of the V-phase armature winding and the impedance of the V-phase armature winding.

  Further, the controller 18 turns on the transistors TR4 and TR6 so as to apply power to the brushless motor 12 so that the rotor does not rotate, so that the V-phase and W-phase armature windings (terminals B and C) are connected to GND. The connection and the U-phase armature winding (terminal A) are not connected (FIG. 3C), and after the observer 20 detects the voltages Vn3 and Vn4, the controller 18 supplies power to the extent that the rotor does not rotate. By turning on the transistors TR3 and TR6 so as to be applied to 12, the V-phase armature winding (terminal B) is connected to the positive potential, the W-phase armature winding (terminal C) is connected to GND, and the U-phase armature winding With the line (terminal A) disconnected, the observer 20 detects the voltages Vn3 ′ and Vn4 ′ (FIG. 3D).

  That is, by switching from the state of FIG. 3C to the state of FIG. 3D, a voltage is easily generated, and the observer 20 detects this, and as described above, the V-phase armature winding The observer 20 can obtain the ratio of the impedance of the current and the impedance of the W-phase armature winding.

  Then, the U-phase armature winding is calculated from the ratio between the obtained impedance of the U-phase armature winding and the impedance of the V-phase armature winding, and the ratio of the impedance of the V-phase armature winding and the impedance of the W-phase armature winding. The observer 20 obtains the ratio of the impedance of the wire, the impedance of the V-phase armature winding, and the impedance of the W-phase armature winding, and from the obtained three-phase impedance ratio, The relative angle of the rotor is derived. Accordingly, the relative angle of the rotor with respect to the three-phase armature winding can be detected without using a sensor such as a hall sensor.

  In the case of a permanent magnet synchronous machine, an induced voltage is generated in the winding during driving. Therefore, it is necessary to subtract the induced voltage component from the terminal voltage of the armature winding of the connectionless phase. In the embodiment, the difference between the terminal voltage in the state of FIG. 3B and the terminal voltage in the state of FIG. 3A, the difference between the terminal voltage in the state of FIG. 3D and the terminal voltage in the state of FIG. However, the present invention is not limited to this. For example, the induced voltage value measured originally may be used, or the induced voltage is calculated using the induced voltage constant. Alternatively, if the induced voltage can be measured during driving, the value may be used.

  In addition, when the potential generation cycle including necessary position information is shorter than the voltage sampling cycle, that is, when the processing for obtaining the impedance ratio including processing such as A / D conversion is not in time, By adjusting the connection period to the positive potential or the connection period to the negative potential until the generation period of the armature winding terminal voltage becomes larger than the voltage sampling period, it becomes possible to detect the terminal voltage of the armature winding, The period during which voltage detection is possible can be extended.

  Further, the driving of the sensorless brushless motor described in the above embodiment may be performed in the entire motor drive region (torque-rotation speed region), but is not limited thereto. You may make it switch to the well-known various sensorless system using an induced voltage on the way.

  In the above embodiment, an example in which a three-phase armature winding is star-connected has been described. However, a three-phase armature winding may be delta-connected.

  Here, a modified example in which the three-phase armature windings are delta-connected will be described. FIG. 4 is a schematic configuration diagram of the brushless motor driving device 11 when the three-phase armature windings are delta-connected. The same components as those in the above embodiment will be described with the same reference numerals.

  The brushless motor 13 includes a three-phase armature winding and a rotor in which U-phase, V-phase, and W-phase armature windings are delta-connected. Each phase U, V, W of the three-phase armature winding is arranged at a pitch of 120 ° as in the above-described embodiment, and the PWM (Pulse Width Modulation) method of the brushless motor driving device 13 is used. It is connected to the output terminal of the switching element group 14 constituting the inverter.

  The switching element group 14 is connected to a DC power source 16 and a capacitor C is connected in parallel. The three-phase armature winding is energized and switched to each phase of the three-phase armature winding by a transistor of the switching element group 14 at a predetermined timing, so that a rotating magnetic field of 120 ° square wave energization is formed.

  The three pairs of transistors TR1 to TR6 as the switching elements constituting the switching element group 14 are also connected in a three-phase bridge as in the above embodiment, and a diode D is connected in parallel to each transistor. It is connected.

  Further, similarly to the above embodiment, the brushless motor driving device 11 is provided with a controller 22 for controlling the driving of the brushless motor 13 and an observer 24 for detecting the position of the rotor of the brushless motor 13. Yes.

  Thus, even when the three-phase armature winding is delta-connected, the relative angle between the three-phase armature winding and the rotor can be detected by obtaining the impedance ratio as in the above embodiment. .

  For example, by turning on the transistors TR1 and TR6 by the controller 22, as shown in FIG. 5B, the terminal F between the U-phase armature winding and the W-phase armature winding is connected to the positive potential, A terminal E between the child winding and the W-phase armature winding is GND-connected, and a terminal D between the U-phase armature winding and the V-phase armature winding is not connected. The terminal voltage Vn1 ′ between the U-phase armature winding and the V-phase armature winding (terminal D) viewed from the positive potential in this state, and the U-phase armature winding and the V-phase armature winding viewed from GND. By detecting the terminal voltage Vn2 ′ between the terminals (terminal D), the ratio of the impedance of the U-phase armature winding to the impedance of the V-phase armature winding can be obtained. At this time, similarly to the above embodiment, the controller 22 turns on the transistors TR2 and TR6 to extract only the voltage change excluding the change in the induced voltage of the armature winding. As shown in FIG. 5A, the terminal F between the U-phase armature winding and the W-phase armature winding, and the terminal E between the V-phase armature winding and the W-phase armature winding are GND-connected, With terminal D between U-phase armature winding and V-phase armature winding disconnected, terminal voltage Vn1 between U-phase armature winding and V-phase armature winding (terminal D) viewed from the positive potential , The observer 24 detects the terminal voltage Vn2 between the U-phase armature winding and the V-phase armature winding (terminal D) as viewed from GND, and subtracts the voltages Vn1 and Vn1 from the voltages Vn1 ′ and Vn2 ′, respectively. Find the ratio. As a result, the ratio between the impedance (AC component) of the U-phase armature winding and the impedance (AC component) of the V-phase armature winding can be obtained more accurately as shown in equation (1).

  Similarly, by turning on the transistors TR2 and TR3 by the controller 22, as shown in FIG. 5D, the terminal D between the U-phase armature winding and the V-phase armature winding is connected to the positive potential. A terminal F between the W-phase armature winding and the U-phase armature winding is GND-connected, and a terminal E between the V-phase armature winding and the W-phase armature winding is not connected. The terminal voltage Vn3 ′ between the V-phase armature winding and the W-phase armature winding (terminal E) viewed from the positive potential in this state, and the V-phase armature winding and the W-phase armature winding viewed from GND. By detecting the terminal voltage Vn4 ′ between the terminals (terminal E), the ratio of the impedance of the V-phase armature winding to the impedance of the W-phase armature winding can be obtained. At this time, similarly to the above embodiment, the controller 22 turns on the transistors TR2 and TR4 to extract only the voltage change excluding the change in the induced voltage of the armature winding, As shown in FIG. 5C, the terminal D between the U-phase armature winding and the V-phase armature winding, and the terminal F between the U-phase armature winding and the W-phase armature winding are connected to GND. A terminal voltage Vn3 between the V-phase armature winding and the W-phase armature winding (terminal E) as viewed from the positive potential, with the terminal E between the V-phase armature winding and the W-phase armature winding disconnected. The observer 24 detects the terminal voltage Vn4 between the V-phase armature winding and the W-phase armature winding (terminal E) as viewed from GND, and subtracts the voltages Vn3 and Vn4 from the voltages Vn3 ′ and Vn4 ′, respectively. Find the ratio. As a result, the ratio between the impedance (AC component) of the V-phase armature winding and the impedance (AC component) of the W-phase armature winding can be obtained more accurately as shown in the equation (2).

  Therefore, similarly to the star connection of the above embodiment, the impedance of the U-phase armature winding (AC component), the impedance of the V-phase armature winding (AC component), and the impedance of the W-phase armature winding (AC The relative angle of the rotor with respect to the three-phase armature winding can be derived from the impedance ratio by using a well-known technique.

  Next, a specific processing flow performed in the carrier cycle by the controller 22 and the observer 24 according to the modification will be described.

  First, by turning on the transistors TR2 and TR6 so that the controller 22 applies power to the brushless motor 13 so that the rotor does not rotate, the terminal F between the U-phase armature winding and the W-phase armature winding, And the terminal E between the V-phase armature winding and the W-phase armature winding is GND-connected, and the terminal D between the U-phase armature winding and the V-phase armature winding is not connected (FIG. 5A). After the observer 24 detects the voltages Vn1 and Vn2, the controller 22 turns on the transistors TR1 and TR6 so as to apply power to the brushless motor 13 so that the rotor does not rotate. Terminal F between W-phase armature winding is connected to plus potential, terminal E between V-phase armature winding and W-phase armature winding is GND-connected, between U-phase armature winding and V-phase armature winding The terminal D of the Server 24 detects the voltage Vn1 ', Vn2' (FIG. 5 (B)).

  That is, by switching from the state of FIG. 5 (A) to the state of FIG. 5 (B), a voltage is easily generated, and this is detected by the observer 24. As described above, the U-phase armature winding The observer 24 can determine the ratio between the impedance of the V-phase armature winding and the impedance of the V-phase armature winding.

  Further, by turning on the transistors TR2 and TR4 so that the controller 22 applies power to the brushless motor 13 so that the rotor does not rotate, a terminal D between the U-phase armature winding and the V-phase armature winding, And the terminal F of the U-phase armature winding and the W-phase armature winding are GND-connected, the terminal E of the V-phase armature winding and the W-phase armature winding are not connected (FIG. 5C), and the observer After 24 detects the voltages Vn3 and Vn4, the controller 22 turns on the transistors TR2 and TR3 so as to apply power to the brushless motor 13 so that the rotor does not rotate. Terminal D between the armature windings is connected to the positive potential, terminal F between the W-phase armature winding and the U-phase armature winding is connected to GND, and the terminal between the V-phase armature winding and the W-phase armature winding E as no connection, observer 4 detects the voltage Vn3 ', Vn4' (FIG. 5 (D)).

  That is, by switching from the state of FIG. 5C to the state of FIG. 5D, a voltage is easily generated, and this is detected by the observer 24. As described above, the V-phase armature winding The observer 24 can determine the ratio of the impedance of the W-phase armature winding.

  Then, the U-phase armature winding is calculated from the ratio between the obtained impedance of the U-phase armature winding and the impedance of the V-phase armature winding, and the ratio of the impedance of the V-phase armature winding and the impedance of the W-phase armature winding. The observer 24 obtains the ratio of the impedance of the wire, the impedance of the V-phase armature winding, and the impedance of the W-phase armature winding, and uses the known three-phase impedance ratio for the three-phase armature winding. The relative angle of the rotor is derived. As a result, even if the three-phase armature winding of the brushless motor 13 is delta-connected, the relative angle between the three-phase armature winding and the rotor can be detected sensorlessly as in the above embodiment. .

  In the above-described embodiment and modification, in order to extract only the voltage change excluding the change in the induced voltage of the armature winding (FIGS. 3A, 3C, 5A) As shown in (C)), one terminal of the armature winding is not connected and the remaining terminals are connected to a negative potential. May be disconnected and the remaining terminals may be connected to a positive potential. For example, in the case of star connection, as shown in FIG. 6A, the V-phase and W-phase armature windings (terminals B and C) are connected to a positive potential, and the U-phase armature winding ( When the terminal A) is not connected and is delta-connected, as shown in FIG. 6B, the terminal F between the U-phase armature winding and the W-phase armature winding, and the V-phase armature winding The terminal E between the W-phase armature winding and the W-phase armature winding may be GND-connected, and the terminal D between the U-phase armature winding and the V-phase armature winding may be left unconnected.

It is a schematic block diagram of the brushless motor drive device concerning embodiment of this invention. (A) is a figure which shows the impedance change which changes with rotation of a rotor, (B) is a figure which shows the impedance change of each phase which changes with rotation of a rotor. (A) is a figure which shows the state which grounded the armature winding of U phase and V phase, and made the armature winding of W phase unconnected, and (B) is a power supply to the armature winding of U phase. It is a figure which shows the state which applied the + voltage of voltage, GND the V-phase armature winding, and made the W-phase armature winding unconnected, (C) is the armature of V-phase and W-phase It is a figure which shows the state which wound the GND and made the U-phase armature winding unconnected, (D) applies the + voltage of the power supply voltage to the V-phase armature winding, and the W-phase armature It is a figure which shows the state which carried out GND of a coil | winding and made the U-phase armature coil | winding unconnected. It is a schematic block diagram of a brushless motor drive device when a three-phase armature winding is delta-connected. (A) is a GND connection between the U-phase armature winding and the W-phase armature winding, and between the V-phase armature winding and the W-phase armature winding, and the U-phase armature winding and the V-phase armature winding. It is a figure which shows the state which made no connection between wires, (B) is + electric potential connection between U phase armature winding and W phase armature winding, V phase armature winding and W phase armature winding It is a figure which shows the state which made the GND connection between the U-phase armature winding and the V-phase armature winding, and (C) is between the U-phase armature winding and the V-phase armature winding, And U-phase armature winding and W-phase armature winding are connected in GND, and V-phase armature winding and W-phase armature winding are not connected. + Potential connection between the child winding and the V-phase armature winding, GND connection between the W-phase armature winding and the U-phase armature winding, and no connection between the V-phase armature winding and the W-phase armature winding It is a figure which shows the state made into the connection. (A) is a figure which shows an example which connected one terminal among the terminals of the armature winding in the star connection, and connected the remaining terminals to the positive potential, and (B) is a terminal of the armature winding in the delta connection. It is a figure which shows an example which connected one terminal among them, and connected the remaining terminal to plus electric potential.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 11 ... Motor drive device, 12, 13 ... Brushless motor, 14 ... Switching element group, 16 ... DC power supply, 18 ... Controller, 20 ... Observer

Claims (9)

A motor that rotates a rotor by sequentially applying electric power to armature windings of a plurality of phases of three or more phases;
A switching element group for converting DC power into AC power by applying on / off of a plurality of switching elements and applying the same to the motor;
Control means for controlling the switching element group to control rotation of the rotor;
The control means detects a terminal voltage of the armature winding when the control means controls the switching element group so as to apply power to the motor so that the rotor does not rotate, and based on the detection result, the armature Deriving means for deriving a relative angle of the rotor to the winding;
A motor drive device comprising:   The motor driving apparatus according to claim 1, wherein the derivation unit obtains an impedance ratio of each phase from a terminal voltage of the armature winding, and derives a relative angle of the rotor from the impedance ratio.   The motor driving apparatus according to claim 1, wherein the derivation unit detects a terminal voltage of the armature winding to which no electric power is applied, and derives the relative angle.   A terminal that is disconnected when the derivation means is controlled so that one terminal of the terminals of the armature winding is not connected and the remaining terminals are connected to a negative potential by the control means. The potential based on the voltage and one terminal of the armature windings are connected to the positive potential by the control means, one of the remaining terminals is connected to the negative potential, and the remaining terminals are not connected. The ratio of the impedance AC component of the armature winding is obtained by comparing the potential based on the terminal voltage that is not connected when controlled so that the relative angle is derived from the obtained ratio. The motor drive device according to claim 1.   The derivation means is disconnected when the control means is controlled so that one of the terminals of the armature winding is not connected and the remaining terminals are connected to a positive potential. A potential based on a terminal voltage, and one terminal of the armature windings is connected to a positive potential by the control means, one of the remaining terminals is connected to a negative potential, and the remaining terminals are not connected. By comparing the potential based on the terminal voltage that is not connected when being controlled to obtain the ratio of the impedance AC component of the armature winding, the relative angle is calculated from the obtained ratio. The motor driving device according to claim 1, wherein the motor driving device is derived.   The motor driving apparatus according to claim 4 or 5, wherein the derivation unit subtracts an induced voltage of the armature winding due to a magnetic flux of a magnet disposed on the rotor to obtain a ratio of the impedance AC component.   The derivation means, when the detectable period of the terminal voltage of the armature winding to be detected is smaller than the voltage sampling period, until the generation period of the terminal voltage of the armature winding becomes larger than the voltage sampling period, The motor drive device according to claim 4 or 5, wherein the terminal voltage of the armature winding is detected by adjusting a connection period to a positive potential or a connection period to a negative potential.   The derivation means obtains the ratio of the impedance alternating current component by comparing a potential difference between a positive side potential of a terminal of the armature winding that is not connected and a ground side potential of the terminal. Or the motor drive device of Claim 5.   The motor drive device according to claim 1, wherein the armature winding is a delta connection.

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