JP2012152032A - Driving device of sensorless brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device of a sensorless brushless motor, capable of detecting an induction voltage that is no reduction by a three-phase independent method, detecting a rotational position with high precision to allow low rotation driving, and suppressing increase in cost.SOLUTION: A driving device 1 of a sensorless brushless motor 9 includes a power supply circuit (inverter circuit 2) which supplies a power supply voltage Vcc to terminals 95U, 95V, and 95W of three-phases of an armature winding, a position detection circuit 3 which detects a rotational position based on an induction voltage VSw at the terminal, and a power supply control circuit 4 which controls timing in an electrification time zone based on the rotational position. The position detection circuit 3 includes a selecting switch 33 which selects and outputs an induction voltage in any one phase, a comparator 34 which compares the induction voltage in any one phase with a predetermined reference voltage for magnitude and outputs a comparison result, and a position detection part 37 which detects a reference rotational position of a rotor by using a change timing of the comparison result.

Description

  The present invention relates to a sensorless brushless motor driving apparatus including a position detection circuit that detects an induced voltage induced in an armature winding of a stator and detects a rotational position of a rotor.

  As one type of DC brushless motor, a sensorless type motor that does not include a sensor that detects the rotational position of a rotor has been put into practical use. This sensorless brushless motor is provided with a position detection circuit that detects the relative rotational positional relationship with the magnetic pole pair of the rotor by detecting the induced voltage induced in the terminal of the armature winding of the stator during the non-energization time zone. It is done. Based on the detected rotational position, the power supply control device sets an energization time zone for supplying the power supply voltage to the armature winding. The power supply circuit is generally composed of an inverter circuit, and supplies a power supply voltage to the armature winding in accordance with a set energization time zone to energize. In motors with three-phase armature windings, a drive system that switches the energized phases sequentially at a 120 ° pitch of the electrical angle according to the rotational position of the rotor is often used, and the energization to multiple phases over 120 ° overlaps. It is also done. In order to adjust the output torque, the normal power supply circuit controls the power supply voltage by a pulse width modulation method (PWM method), a pulse voltage amplitude control method (PAM method), or the like.

  The induced voltage detected by the position detection circuit described above is generated when the magnetic flux from the magnetic pole pair of the rotor is linked to the armature winding in the non-energization time zone. Therefore, the induced voltage changes depending on the relative rotational position relationship between the armature winding and the rotor, and can be an index for detecting the rotational position. However, the phase in which the induced voltage is generated is switched sequentially with the switching of the energized phase. As a circuit method for detecting the induced voltage, two methods, a three-phase synthesis method and a three-phase independent method, have been conventionally used.

  In the brushless motor control method of Patent Document 1, an example of a three-phase composition type position detection circuit is disclosed. That is, the position detection circuit has a combined circuit composed of Y-connected resistors, and obtains a virtual neutral point voltage obtained by combining and dividing the terminal voltages of the armature windings U, V, and W. Further, the virtual neutral point voltage and the predetermined voltage are compared by a comparison circuit to obtain a position detection signal. In this method, even if an induced voltage is generated at any phase terminal, it is detected at the Y-connection neutral point.

  In addition, the brushless DC motor driving device of Patent Document 2 discloses an example of a three-phase independent type position detection circuit. In other words, the rotor position detection means (position detection circuit) relates to line voltage generation means for generating line voltages of the three-phase armature windings, amplification means for amplifying signals related to the line voltages, and line voltages. Comparing means for comparing the signal and the amplified signal. That is, a line voltage generating means, an amplifying means, and a comparing means are provided for each phase, and the rotor position is detected independently for each of the three phases.

JP 2000-287480 A JP-A-8-331883

  By the way, in the position detection circuit of the three-phase synthesis method including Patent Document 1, since the influence of the power supply voltage of the energized phase is superimposed on the Y-connection neutral point, the detected induced voltage is the three-phase independent method (1 / 3), and there is a problem that the detection accuracy of the rotational position is lowered. In particular, it is known that when the rotation speed of the rotor is low and the rotation speed is low, the change of the magnetic flux interlinking with the armature winding becomes slow, so that the induced voltage decreases and position detection becomes difficult.

  On the other hand, in the three-phase independent type position detection circuit including Patent Document 2, it is preferable that the induced voltage is large, but since the position detection circuit including the comparison unit is provided independently for each of the three phases, There is a problem that the cost increases compared to the three-phase synthesis method.

  The present invention has been made in view of the above-mentioned problems of the background art. The three-phase independent method detects the induced voltage without reducing the induced voltage, detects the rotational position with high accuracy, enables low rotational driving, and is cost effective. It is a problem to be solved to provide a sensorless brushless motor driving device that suppresses an increase in the above.

  The invention of a sensorless brushless motor driving apparatus according to claim 1 that solves the above-described problems is a three-phase armature winding of a sensorless brushless motor comprising a stator having a three-phase armature winding and a rotor having a magnetic pole pair. A power supply circuit for supplying a power supply voltage to the terminal of the rotor, and an induced voltage induced in the terminal during a non-energization time zone in which the power supply voltage is not supplied from the power supply circuit, and a rotational position of the rotor based on the induced voltage And a power supply control signal for controlling a timing of a power supply time period for supplying the power supply voltage based on the rotational position of the rotor detected by the position detection circuit and setting the power supply circuit to the power supply circuit. A sensorless brushless motor driving device comprising: a power supply control circuit that sends out the three-phase induced voltage. A selector switch that selects and outputs the induced voltage of any one phase according to control from the power supply control circuit, and inputs the induced voltage of any one phase according to the control from the power supply control circuit, and compares the magnitude with a predetermined reference voltage. A comparator that outputs a comparison result, and a position detection unit that receives the comparison result of the comparator and detects a reference rotational position of the rotor with a change timing of the comparison result. And

  According to a second aspect of the present invention, in the first aspect, the three-phase armature winding is Δ-connected, and the reference voltage of the comparator of the position detection circuit is an intermediate level value of the power supply voltage. It is characterized by.

  The invention according to claim 3 is the invention according to claim 1, wherein the three-phase armature winding is Y-connected, and the reference voltage of the comparator of the position detection circuit is a neutral point voltage of the Y-connection. It is characterized by being.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the power supply circuit includes an inverter circuit that varies a duty ratio of the power supply voltage by a pulse width modulation method.

  According to a fifth aspect of the present invention, the power supply control circuit according to any one of the first to fourth aspects is based on the rotational position of the rotor detected by the position detection circuit, and the power supply circuit and the position detection The energization control signal is set in consideration of a lead angle that compensates for a transmission delay time in the circuit, and the power supply control circuit further includes the induced voltage from a start point of the non-energization time zone in at least one phase terminal. A rise early period until the intermediate voltage value of the power supply voltage reaches the intermediate level value, a late rise time period from when the induced voltage reaches the intermediate level value to an end point of the non-energization time zone, and the at least one The first half of the fall time until the induced voltage decreases and reaches the intermediate level value of the power supply voltage from the start point of the non-energization time zone at the phase terminal. And a time detection unit for detecting at least one of a set of late fall times from the time when the induced voltage reaches the intermediate level value to an end point of the non-energization time zone, the rise early period and the rise late period A lead angle determination unit that determines at least one of the magnitude relationship between time and the magnitude relationship between the fall first period and the fall late time; and at least one magnitude relation of the at least one phase. And an advance angle adjusting unit that adjusts the advance angle based on the determination result.

  The sensorless brushless motor drive device according to claim 1 includes a power supply circuit, a position detection circuit, and a power supply control circuit, and the position detection circuit selects and outputs one of the three-phase induced voltages. A changeover switch, a comparator that compares the induced voltage of any one phase with a predetermined reference voltage and outputs a comparison result, and a position detection unit that detects the reference rotational position of the rotor with the change timing of the comparison result And have. For this reason, the induced voltage of each phase selected by the change-over switch has the same magnitude as that of the three-phase independent method, and the rotational position can be detected with high accuracy, and low rotational driving is possible. Further, unlike the conventional three-phase independent method, only one comparator is required, so that an increase in cost can be suppressed.

  In the invention according to claim 2, the three-phase armature windings are △ -connected, and the reference voltage of the comparator of the position detection circuit is an intermediate level value of the power supply voltage. For the armature winding of Δ connection, the reference rotational position of the rotor can be detected by using the intermediate level value of the power supply voltage as the reference voltage of the comparator.

  In the invention according to claim 3, the three-phase armature winding is Y-connected, and the reference voltage of the comparator of the position detection circuit is the neutral voltage of the Y-connection. For the Y-connected armature winding, the reference rotational position of the rotor can be detected by using the neutral point voltage as the reference voltage of the comparator.

  In the invention according to claim 4, the power supply circuit includes an inverter circuit that makes the duty ratio of the power supply voltage variable by a pulse width modulation method. The present invention can be implemented in combination with a pulse width modulation type inverter circuit, and the same effect as that of the first aspect is produced.

  In the invention according to claim 5, the power supply control circuit sets the energization control signal in consideration of the advance angle that compensates for the transmission delay time in the power supply circuit and the position detection circuit, and the time detection unit and the advance angle determination unit And a lead angle adjusting section. The present invention can be implemented in combination with a power supply control circuit for controlling the lead angle, and the same effect as that of the first aspect is produced. In addition, by adjusting the advance angle based on the determination result of the magnitude relationship between the first and second periods of the rise or fall of the induced voltage, the timing of the energizing time zone is optimized and good motor efficiency is obtained. be able to.

FIG. 2 is a diagram illustrating an overall device configuration of a sensorless brushless motor driving device according to the first embodiment. FIG. 5 is a table illustrating a method for controlling energization and non-energization time zones of a sensorless brushless motor by a power supply control circuit and controlling a changeover switch in the drive device of the first embodiment. It is the figure which illustrated the voltage waveform which generate | occur | produces in each part by control shown by FIG. It is a figure explaining an example of the whole apparatus structure of the drive device of the conventional three-phase composition system. FIG. 4 is a waveform of an induced voltage input to the positive input terminal of the comparator of the position detection circuit, where (1) indicates the induced voltage of the driving device of the first embodiment, and (2) indicates the combined voltage of the conventional driving device. ing. It is a figure explaining the whole apparatus structure of the drive device of the sensorless brushless motor of 2nd Embodiment. It is a figure explaining the whole apparatus structure of the drive device of the sensorless brushless motor of 3rd Embodiment. It is a figure of the flowchart explaining control operation of the time detection part of the power supply control circuit, the advance angle determination part, and the advance angle adjustment part in 3rd Embodiment. It is a figure of the waveform example of the induced voltage explaining the control operation in 3rd Embodiment.

  The configuration and driving operation of the sensorless brushless motor driving apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3 and FIG. 5. FIG. 1 is a diagram illustrating an overall device configuration of a sensorless brushless motor driving device 1 according to the first embodiment. The drive device 1 is a device that drives the sensorless brushless motor 9 using an inverter circuit 2 that varies the duty ratio of the power supply voltage by a pulse width modulation (PWM) method (hereinafter, pulse width modulation is abbreviated as PWM).

  The sensorless brushless motor 9 includes a stator 91 having Δ-connected three-phase armature windings 92, 93, 94, and a rotor having a magnetic pole pair (not shown), and a sensor for detecting the rotational position of the rotor. Absent. The stator 91 is provided with a U-phase terminal 95U, a V-phase terminal 95V, and a W-phase terminal 95W. Between the U-phase terminal 95U and the V-phase terminal 95V, an armature winding 92 between UV is connected. Similarly, between the V-phase terminal 95V and the W-phase terminal 95W, an inter-VW armature winding 93 and a W-phase are connected. An inter-WU armature winding 94 is connected between the terminal 95W and the U-phase terminal 95U. In the first embodiment, there are no particular restrictions on the number of poles of the armature windings 92, 93, 94 of the stator 91 and the number of magnetic pole pairs of the rotor.

  The drive device 1 includes an inverter circuit 2 that constitutes a power supply circuit, a position detection circuit 3 that detects the rotational position of the rotor, and a power supply control circuit 4 that sends an energization control signal SC to the inverter circuit 2. A DC power supply (not shown) is connected to the input terminal 21 and the ground terminal E of the inverter circuit 2 so that the power supply voltage Vcc is supplied.

  The inverter circuit 2 is composed of a three-phase bridge circuit as shown in the figure. More specifically, a U-phase power supply side switching element 22U and a U-phase ground side switching element 23U are connected in series between the input terminal 21 and the ground terminal E, and a U-phase output terminal 24U is connected between the elements 22U and 23U. Is provided. Similarly, a V-phase output terminal 24V is provided between the V-phase power source side switching element 22V and the V-phase ground side switching element 23V, and the W-phase power source side switching element 22W and the W-phase ground side switching element 23W are connected to each other. A W-phase output terminal 24W is provided between them. For example, a field effect transistor (FET) can be used for each of the switching elements 22U to 22W and 23U to 23W, and the switching elements 22U to 22W and 23U to 23W can be switched and controlled to be in a conduction state and a cutoff state by an energization control signal SC. The phase output terminals 24U, 24V, and 24W are connected to the phase terminals 95U, 95V, and 95W of the stator 91 by power lines 25U, 25V, and 25W, respectively.

  The phase terminals 95U, 95V, and 95W of the stator 91 take three states by opening / closing control of the switching elements 22U to 22W and 23U to 23W of the inverter circuit 2. Since these three states are the same in each phase, the U-phase terminal 95 will be described as an example. U-phase terminal 95U is constrained to power supply voltage Vcc when U-phase power supply side switching element 22U is in a conductive state and U-phase ground-side switching element 23U is in a cut-off state, and U-phase power supply side switching element 22U is in a cut-off state. When the ground side switching element 23U is in the conductive state, it is constrained to zero voltage, and when the U-phase power supply side switching element 22U and the ground side switching element 23U are both in the cut-off state, the high impedance state is established.

  An induced voltage VUi is induced at the U-phase terminal 95U in the high impedance state. This U-phase induced voltage VUi is generated when the magnetic flux from the rotor magnetic pole pair is linked to the UV armature winding 92 and the WU armature winding 94 connected to the U-phase terminal 95U. Therefore, the U-phase induced voltage VUi changes depending on the relative rotational position relationship between the UV and WU armature windings 92 and 94 and the rotor, and can be an index for detecting the rotational position. It should be noted that control in which both the U-phase power supply side switching element 22U and the U-phase ground side switching element 23U are in a conductive state is prohibited, and a power supply voltage short-circuit failure is prevented.

  The position detection circuit 3 includes a changeover switch 33, a comparator 34, and a position detection unit 37. The three-phase input terminals 33U, 33V, and 33W of the selector switch 33 are connected to the power supply lines 25U, 25V, and 25W, respectively, so that the induced voltages VUi, VVi, and VWi of the phase terminals 95U, 95V, and 95W are input. It has become. The output terminal 33out of the changeover switch 33 is connected to the positive input terminal + of the comparator 34. The change-over switch 33 is controlled by a change-over control signal SW from the inverter control unit 45 in the power supply control circuit 4, and is one of the induced voltages (VUi, VVi, VWi) in the non-energization time zone among the input terminals 33U, 33V, 33W. ) Is selectively conducted to the output terminal 33out. That is, any one of the induced voltages VUi, VVi, and VWi is sequentially selected to be the induced voltage Vsw, and is input to the positive side input terminal + of the comparator 34.

  On the other hand, an intermediate level value VM (= Vcc / 2) obtained by dividing the power supply voltage Vcc of the DC power supply device by half with an equal resistance value r is input to the negative input terminal − of the comparator 34 as a reference voltage. . The comparator 34 compares the induced voltage Vsw input to the positive input terminal + with the intermediate level value VM of the negative input terminal − and outputs a position signal SX. That is, if the induced voltage Vsw is lower than the intermediate level value VM at the output terminal 35 of the comparator 34, the position signal SX becomes low level L, and if the induced voltage Vsw becomes equal to or higher than the intermediate level value VM, the position signal SX becomes high level. Become. The output terminal 35 of the comparator 34 is connected to the position detection unit 37 and receives the position signal SX.

  The position detection unit 37 receives the position signal SX output from the comparator 34 as will be described in detail later with reference to the waveform example, and receives the reference of the rotor with the change timing between the low level L and the high level H. Detect the rotational position. Further, the rotational speed of the rotor is detected from the time difference at which a plurality of reference rotational positions are detected.

  The power supply control circuit 4 includes an inverter control unit 45 and a PWM generation unit 46. The inverter control unit 45 acquires the rotor reference rotational position and rotational speed signals detected by the position detection unit 37 of the position detection circuit 3, and acquires the PWM signal SP from the PWM generation unit 46. The inverter control unit 45 sets and sends an energization control signal SC for controlling the inverter circuit 2 in accordance with the acquired signal. Further, the inverter control unit 45 sets the phase that becomes the non-energization time zone in the inverter circuit 2 as the switching control signal SW and sends it to the switching switch 33. The function of the power supply control circuit 4 will be described in detail later in the operation description.

  Next, the driving operation of the motor 9 by the sensorless brushless motor driving apparatus 1 of the first embodiment configured as described above will be described. FIG. 2 is a table showing a method for controlling the energization and non-energization time zones of the sensorless brushless motor 9 by the power supply control circuit 4 and controlling the changeover switch 33 in the driving apparatus 1 of the first embodiment. is there. As illustrated, the power supply control circuit 4 performs the state control of the phase terminals 95U, 95V, and 95W and the control of the changeover switch 33 in six periods 1) to 6). The upper three columns in the list indicate the states of the phase terminals 95U, 95V, and 95W during the corresponding period. In the table, “Hi-Z” indicates a high impedance state, “L” indicates a zero voltage constraint state, and “PWM” indicates a PWM control state. The lower three columns in the list indicate “ON” the conduction phases in the input terminals 33U, 33V, and 33W of the changeover switch 33 set by the changeover control signal SW from the inverter control unit 45.

  For example, in the period 1) of FIG. 2, the column of the U phase terminal is “Hi-Z”, and both the U phase power supply side switching element 22U and the U phase ground side switching element 23U of the inverter circuit 2 are in the cut-off state. Thus, the U-phase terminal 95U is in a high impedance state. The column of the V phase terminal is “L”, the V phase power supply side switching element 22V of the inverter circuit 2 is cut off, the V phase ground side switching element 23V is turned on, and the V phase terminal 95V is It shows that it is restrained to zero voltage. The column of the W phase terminal is “PWM”, and the W phase ground side switching element 23W of the inverter circuit 2 is cut off and the W phase power supply side switching element 22W is in a conductive state at the commanded PWM frequency and duty ratio. It also indicates that switching control is performed in the shut-off state. As a result, a rectangular wave that oscillates to the power supply voltage Vcc and the zero voltage is generated at the W-phase terminal 95W. Therefore, the inter-VW armature winding 93 connected between the W-phase terminal 95W and the V-phase terminal 95V is energized by PWM control. Period 1) is a non-energization time zone of the U-phase terminal 95U, and the U-phase induced voltage VUi can be detected.

  Furthermore, since the U-phase terminal 95U is in the non-energization time zone, the inverter control unit 45 sets the switching control signal SW to the U-phase.

  Similarly, in the period 2), the column of the U-phase terminal is “PWM”, and the U-phase terminal 95U generates a rectangular wave that oscillates to the power supply voltage Vcc and the zero voltage at the commanded PWM frequency and duty ratio. The column of the V-phase terminal is “L”, which indicates that the constraint on the zero voltage of the V-phase terminal 95V continues. The column of the W-phase terminal is “Hi-Z”, which indicates that the W-phase terminal 95W is in a high impedance state. Thereby, the armature winding 92 between UV connected between the U-phase terminal 95U and the V-phase terminal 95V is energized by PWM control. Period 2) is a non-energization time zone of the W-phase terminal 95W, and the W-phase induced voltage VWi can be detected.

  Further, since W phase terminal 95W is in the non-energization time zone, inverter control unit 45 sets switching control signal SW to the W phase. Similarly, in the periods 3) to 6), the state of each phase terminal 95U, 95V, 95W, the armature winding to be energized, and the phase setting of the switching control signal SW are changed and controlled in order.

  Since each of the periods 1) to 6) corresponds to an electrical angle of 60 °, the power supply control unit 4 performs control so that the periods 1) to 6) are equal to each other. In addition, following the period 6), the process returns to the period 1), and the same control is repeated.

  When the energization and non-energization time zones and the switching control signal SW are controlled as shown in FIG. 2, the voltage waveforms of the respective parts illustrated in FIG. 3 are generated. FIG. 3 is a diagram illustrating voltage waveforms generated in the respective parts by the control shown in FIG. The horizontal axis in FIG. 3 is a common time axis and the periods 1) to 6) correspond to FIG. 2, and the waveforms are U phase terminal voltage VU, V phase terminal voltage VV, and W phase terminal voltage VW in order from the top. The induced voltage Vsw and the intermediate level value VM at the output terminal 33out of the changeover switch 33 and the changeover control signal SW are shown. In the U-phase terminal voltage VU in the figure, the repetition of the rectangular wave generated in the period 2) and the period 3) indicates the energization time period by the PWM control, and the period 5) and the period 6) are the energization time by the zero voltage constraint. The band is shown. In addition, the waveform of the U-phase terminal voltage VU in which the increase slope generated in the period 1) and the PWM control overlap, and the waveform of the decrease slope generated in the period 4) and the PWM control overlap are not The induced voltage VUi in the energization time zone is shown. The V-phase terminal voltage VV and the W-phase terminal voltage VW in the figure can be viewed in the same way except that the periods 1) to 6) are different.

  Further, in each phase terminal voltage VU, VV, VW, a back electromotive force waveform Z is generated by opening / closing of each switching element 22U-22W, 23U-23W, and is superimposed on the boundary of each period 1) -6). Yes. Although the back electromotive force waveform Z has a certain time width in the figure, it is actually an instantaneous waveform. Therefore, the start point and end point of the energization time zone and the non-energization time zone can be detected from the back electromotive force waveform Z.

  On the other hand, an induced voltage Vsw in which the induced voltages VUi, VVi, and VWi of each phase are sequentially switched is generated at the output terminal 33out of the changeover switch 33 of the position detection circuit 3. The induced voltage Vsw has a waveform in which the back electromotive force waveform Z is superimposed on a waveform in which the induced voltages VUi, VVi, and VWi of each phase increase and decrease. In the waveform example of FIG. 3, the induced voltage Vsw includes an increase in the U-phase induced voltage VUi in the period 1), a decrease in the W-phase induced voltage VWi in the period 2), an increase in the V-phase induced voltage VVi in the period 3), and a period 4 ) Decrease in U-phase induced voltage VUi, increase in W-phase induced voltage VWi in period 5), and decrease in V-phase induced voltage VVi in period 6), and counter electromotive force at the boundary of each period 1) to 6). The waveform Z is a superimposed waveform.

  This induced voltage Vsw is input to the positive input terminal + of the comparator 34 of the position detection circuit 3. At the output terminal 35 of the comparator 34, the low level L and the high level H of the position signal SX are switched at the timing when the waveform of the induced voltage Vsw intersects the intermediate level value VM. The position detection unit 37 detects the reference rotational position of the rotor at the timing when the low level L and the high level H are switched, that is, at points P1 to P6 where the waveform of the induced voltage Vsw intersects the intermediate level value VM in FIG. To do. Here, the fact that the induced voltages VUi to VWi become the intermediate level value VM of the power supply voltage Vcc means that the intermediate point of the magnetic pole pair of the rotor is located in front of the armature windings 92 to 94. . Therefore, for example, the points P1 to P6 can be set to electrical angles of 30 °, 90 °, 150 ° 210 °, 270 °, and 330 °, respectively. Further, the rotational speed of the rotor can be detected from the generation time intervals of the points P1 to P6. In the position detector 37, the back electromotive force waveform Z is masked so as not to be affected.

  The inverter control unit 45 of the power supply control circuit 4 receives the timing at which the rotor has reached the reference rotation position from the position detection unit 37 of the position detection circuit 3 (corresponding to the timings P1 to P6 in the waveform example of FIG. 3) and the rotation speed. And a PWM signal SP from the PWM generator 46. The PWM signal SP is a signal that indicates the PWM frequency and the duty ratio. The inverter control unit 45 sets and sends an energization control signal SC that controls opening / closing of the switching elements 22U to 22W and 23U to 23W of the inverter circuit 2 according to the acquired signal. Further, the above-described switching control signal SW is set and sent to the selector switch 33.

  Next, the effect of the driving device 1 of the first embodiment will be described in comparison with a conventional three-phase synthesis driving device. FIG. 4 is a diagram for explaining an example of the entire configuration of a conventional three-phase combining type driving device 100. As can be seen by comparing FIG. 4 with FIG. 1, the conventional driving device 100 does not have the changeover switch 33 in the position detection circuit 300 but instead has three combined resistors 31U, 31V, and 31W. The configuration of this part is the same as in the first embodiment. The combined resistors 31U, 31V, and 31W have the same resistance value R, and are connected between the power lines 25U, 25V, and 25W of the respective phases and the common combined point 32, respectively. That is, the three combined resistors 31U, 31V, 31W are Y-connected, and the combined point 32 is a Y-connected neutral point. A composite voltage Vmix is generated at the composite point 32 by combining the induced voltages VUi, VVi, and VWi of the phase terminals 95U, 95V, and 95W of the stator 91. The composite point 32 is connected to the positive side input terminal + of the comparator 34 and receives the composite voltage Vmix.

  FIG. 5 is a waveform of the induced voltage input to the positive input terminal + of the comparator 34 of the position detection circuits 3 and 30. (1) is the induced voltage Vsw of the driving device 1 of the first embodiment, (2 ) Shows the combined voltage Vmix of the conventional driving device 100. As shown in the figure, the induced voltage Vsw of the first embodiment is three times the conventional three-phase composite voltage Vmix and has the same magnitude as the three-phase independent method. Accordingly, even when the change in the induced voltage Vsw becomes slow at the time of low rotation at which the rotation speed of the rotor is slow, the generation timing of the points P1 to P6 intersecting with the intermediate level value VM can be detected with high accuracy, and low rotation driving can be performed. It becomes possible. Further, in the conventional three-phase independent method, only one comparator 34 is required, so that an increase in cost can be suppressed.

  Next, a sensorless brushless motor driving apparatus according to a second embodiment in which the connection method of the armature windings 92A to 94A and the reference voltage of the comparator 34 of the position detection circuit 30 are different will be described. FIG. 6 is a diagram illustrating the overall configuration of the sensorless brushless motor driving apparatus 10 according to the second embodiment. As illustrated, in the second embodiment, the three-phase armature windings 92A to 94A are Y-connected. That is, U-phase armature winding 92A is connected between U-phase terminal 95U and neutral point 95N. Similarly, V-phase armature winding 93A and W-phase are connected between V-phase terminal 95V and neutral point 95N. W-phase armature winding 94A is connected between terminal 95W and neutral point 95N. The neutral point 95N is drawn out of the motor 90 and connected to the negative input terminal − of the comparator 34. That is, the neutral point voltage VN of the Y connection of the armature winding is the reference voltage of the comparator 34. The structure of the other part of 2nd Embodiment is the same as 1st Embodiment.

  In the second embodiment, for example, when the U-phase terminal 95U is in a high impedance state, the V-phase terminal 95V is in a zero voltage restraint state, and the W-phase terminal 95W is in a PWM control state, the power supply voltage Vcc is V-phase with the W-phase terminal 95W. It is supplied between the terminals 95V. That is, W-phase armature winding 94A and V-phase armature winding 93A are energized, and neutral point voltage VN generated at neutral point 95N matches half of power supply voltage Vcc, that is, intermediate level value VM. Therefore, the driving operation of the driving device 10 of the second embodiment is substantially the same as that of the first embodiment, and the effect is the same, and thus the description thereof is omitted.

  Next, a sensorless brushless motor driving apparatus according to a third embodiment that controls the advance angle A will be described. The advance angle A compensates for the electric signal transmission delay time in the inverter circuit 2 and the position detection circuit 3, optimizes the timing of the energization time zones of the armature windings 92 to 94 of the stator 91, and improves the motor efficiency. For the amount. FIG. 7 is a diagram for explaining the overall device configuration of the sensorless brushless motor driving device 11 according to the third embodiment. As shown in the figure, in the third embodiment, the configuration of the power supply control circuit 40 is different from that of the first embodiment, and the configuration of other parts is the same. The power supply control circuit 40 includes a time detection unit 41, an advance angle determination unit 42, an advance angle adjustment unit 43, a timing generation unit 44, an inverter control unit 45, and a PWM generation unit 46. The time detection unit 41 receives the position signal SX from the comparator 34 and the energized phase switching signal SY from the inverter control unit 45. The energization phase switching signal SY is a signal indicating the start point and end point of the energization time zone and the non-energization time zone.

  FIG. 8 is a flowchart illustrating the control operations of the time detection unit 41, the advance angle determination unit 42, and the advance angle adjustment unit 43 of the power supply control circuit 4 in the third embodiment. FIG. 9 is a diagram showing an example of a waveform of the induced voltage Vsw for explaining the control operation in the third embodiment. In step S1 of FIG. 8, the time detection unit 41 detects the rising first period time Tr1 and the rising second period time Tr2. As a specific example, the time detection unit 41 is in the period 1) of the waveform example of FIG. 9 and the first phase of the rise from the start point of the U-phase non-energization time period until the U-phase induced voltage VUi increases to reach the intermediate level value VM. A time period Tr1U and a set of rising late time Tr2U from the time when U-phase induced voltage VUi reaches intermediate level value VM to the end point of the non-energization time zone are detected. Supplementally, the start point and end point of the non-energization time zone are obtained from the energized phase switching signal SY, and the arrival at the intermediate level value VM is obtained at the timing when the output of the comparator 34 is switched. Note that the back electromotive force waveform Z generated when the energized phase is switched is masked so as not to be affected.

  In step S2 of FIG. 8, the time detection unit 41 detects the falling first half time Tf1 and the falling late time Tf2. As a specific example, the time detection unit 41 falls in the period 2) of the waveform example in FIG. 9 until the W-phase induced voltage VWi decreases from the start point of the W-phase non-energization time period until the intermediate level value VM is reached. A set of the fall time Tf2W from the first period Tf1W and the W-phase induced voltage VWi reaching the intermediate level value VM to the end point of the non-energization time period is detected. In the next step S3, it is determined whether or not a total of six sets of three phases have been collected. In the waveform example of FIG. 9, since six sets are collected by performing steps S1 and S2 three times and performing detection in periods 1) to 6), the process proceeds to step S4.

  In step S4, the advance angle determination unit 42 makes a total of six sets of the previous period T1 (Tr1U, Tr1V, Tr1W, Tf1U, Tf1V, Tf1W) and the later period T2 (Tr2U, Tr2V, Tr2W, Tf2U, Tf2V, Tf2W). Determine the magnitude relationship. When determining the magnitude relationship, a predetermined threshold value is provided. If the difference is less than the predetermined threshold value, the difference is approximately the same, and the magnitude is not determined. If there is a difference greater than or equal to a predetermined threshold value, it is determined that the first period time T1> the second period time T2, or the first period time T1 <the second period time T2. After completion of the determination, the process proceeds to step S5. In the flowchart of FIG. 9, the magnitude relationship is determined at a time when six sets are gathered. Alternatively, the magnitude relationship is judged for each set, and when six judgment results are gathered, the process proceeds to step S5. Also good.

  In step S <b> 5, the advance angle adjustment unit 43 investigates the majority logic of the determination results of a total of 6 sets of magnitude relations. In the majority decision logic, the determination result occupying the largest number is adopted, and the determination result to be taken in advance is determined for the possibility that the determination result is divided into 3 to 3 or 2 to 2 to 2. According to the majority logic, the current value of the advance angle A is maintained at the first period T1 = the second period T2, and the process returns to step S1. When the previous period T1> the latter period T2, the process proceeds to step S6 and the advance angle A is decreased by the increment ΔA. When the previous period T1 <the latter period T2, the process proceeds to step S7 and the advance angle A is increased by the increment ΔA. After step S6 and step S7, the process returns to step S1 and the same control operation is performed for the next electrical angle of 360 °.

  The timing generation unit 44 acquires, from the position detection unit 37 of the position detection circuit 3, the timing at which the rotor has reached the reference rotation position (corresponding to the respective timings P1 to P6 in the waveform example of FIG. 9) and the rotation speed, The advance angle A that has been adjusted is acquired from the advance angle adjustment unit 43. Then, the timing generator 44 sets the advance angle control signal SA so that the advance angle A precedes the reference rotational position of the rotor. The advance angle control signal SA is a signal for setting a period corresponding to an electrical angle of 360 ° and instructing the state of each phase terminal in 360 °. As a result, the timing of each 120 ° energization time zone of PWM control and zero voltage constraint of each phase terminal 95U to 95W is controlled. The advance angle control signal SA is sent to the inverter control unit 45.

  The inverter control unit 45 acquires the advance angle control signal SA from the timing generation unit 44 and acquires the PWM signal SP from the PWM generation unit 46. The PWM signal SP is a signal that indicates the PWM frequency and the duty ratio. The inverter control unit 45 sets and sends an energization control signal SC that controls opening and closing of the switching elements 22U to 22W and 23U to 23W of the inverter circuit 2 in accordance with the acquired advance angle control signal SA and PWM signal SP. As can be seen from the above description, the advance angle control signal SA controls the generation timing of the periods 1) to 6) in FIG. 3, and the PWM signal SP has a rectangular wave shape that repeats in a shorter cycle than the periods 1) to 6). To control.

  In the waveform example of FIG. 9, the first period T1 (Tr1U, Tf1W,...) And the latter period T2 (Tr2U, Tf2W,...) Are substantially equal. This means that the timing control of the energization time zone is good, that is, the advance angle A is set appropriately. At this time, it is determined in step S4 of FIG. 8 that the first period time T1 = the second period time T2, and the current value of the advance angle A is maintained.

  Further, if the advance angle A is set improperly, there is a magnitude relationship between the first period time T1 (Tr1U, Tf1W,...) And the second period time T2 (Tr2U, Tf2W,...). To adjust the advance angle A. Thereby, the timing of the energization time zone of each phase terminal 95U-95W is optimized. Therefore, the relative rotational positional relationship between the rotating magnetic field formed by the armature windings 92 to 94 and the magnetic pole pair of the rotor is properly maintained, and good motor efficiency can be obtained.

  The present invention can also be implemented in a configuration including an inverter circuit of a control system in which energization to a plurality of phases is overlapped with an energization time period exceeding 120 ° of the electrical angle. Further, the present invention is not limited to the PWM inverter circuit 2 and can be implemented in a configuration including a PAM inverter circuit and other control power supply circuits. The present invention can be applied and modified in various other ways.

1, 10, 11: Sensorless brushless motor drive device 2: Inverter circuit (power circuit)
21: Input terminal 22U, 22V, 22W: U phase, V phase, W phase power supply side switching element 23U, 23V, 23W: U phase, V phase, W phase ground side switching element 24U, 24V, 24W: U phase, V-phase, W-phase output terminals 25U, 25V, 25W: Power supply line E: Ground terminal 3: Position detection circuit 33: Changeover switch 33U, 33V, 33W: Input terminal
33out: Output terminal 33
34: Comparator 35: Output terminal 37: Position detection unit 4, 40: Power supply control circuit 41: Time detection unit 42: Advance angle determination unit 43: Advance angle adjustment unit 44: Timing generation unit 45 Inverter control unit 46: PWM generation Part 9, 90: Sensorless brushless motor 91: Stator 92, 93, 94: Between UV, VW, WU armature winding 92A, 93A, 94A: U phase, V phase, W phase armature winding 95U, 95V 95W: U-phase, V-phase, W-phase terminal 95N: Neutral point 100: Conventional three-phase combined drive device 300: Position detection circuit 31U, 31V, 31W: Combined resistor 32: Combined point Vcc: Power supply voltage VM : Intermediate level value VU, VV, VW: U phase, V phase, W phase terminal voltage VUi, VVi, VWi: U phase, V phase, W phase induced voltage Vsw: induced voltage VN: neutral point voltage of Y connection mix: Composite voltage Tr1U, Tr1V, Tr1W: Early rise time Tr2U, Tr2V, Tr2W: Late rise time Tf1U, Tf1V, Tf1W: Early fall time Tf2U, Tf2V, Tf2W: Late fall time A: Lead angle SX: Position signal SA: Lead angle control signal SP: PWM signal SC: Energization control signal SW: Switching control signal

Claims (5)

A power supply circuit for supplying a power supply voltage to the three-phase terminals of the armature winding of a sensorless brushless motor including a stator having a three-phase armature winding and a rotor having a magnetic pole pair;
A position detection circuit that detects an induced voltage induced in the terminal during a non-energization time zone in which the power supply voltage is not supplied from the power supply circuit, and detects a rotational position of the rotor based on the induced voltage;
A power supply control circuit that sets an energization control signal for controlling the timing of an energization time period for supplying the power supply voltage based on the rotational position of the rotor detected by the position detection circuit, and sends the power supply control signal to the power supply circuit; A sensorless brushless motor drive device comprising:
The position detection circuit includes:
Each of the three-phase induced voltages is input, a changeover switch that selects and outputs one-phase induced voltage according to control from the power supply control circuit, and
A comparator that receives the induced voltage of any one of the phases as input and outputs a comparison result by comparing with a predetermined reference voltage;
A drive unit for a sensorless brushless motor, comprising: a position detection unit that receives the comparison result of the comparator as input and detects a reference rotational position of the rotor with a change timing of the comparison result. In claim 1, the three-phase armature winding is a △ connection,
The sensorless brushless motor driving apparatus, wherein the reference voltage of the comparator of the position detection circuit is an intermediate level value of the power supply voltage. In claim 1, the three-phase armature winding is Y-connected,
The sensorless brushless motor driving apparatus, wherein the reference voltage of the comparator of the position detection circuit is a neutral point voltage of the Y connection.   4. The sensorless brushless motor driving device according to claim 1, wherein the power supply circuit includes an inverter circuit that varies a duty ratio of the power supply voltage by a pulse width modulation method. 5. 5. The power supply control circuit according to claim 1, wherein the power supply control circuit is based on the rotational position of the rotor detected by the position detection circuit and compensates for a transmission delay time in the power supply circuit and the position detection circuit. The energization control signal is set in consideration of the advance angle,
Further, the power supply control circuit includes:
At least one phase of the non-energization time zone from the start point of the non-energization time period until the induced voltage increases until the intermediate level value of the power supply voltage is reached and the induced voltage reaches the intermediate level value, and the non- A set of late rising time until the end of energizing time zone, and the first half of falling until the induced voltage decreases and reaches the intermediate level value of the power supply voltage from the start point of the non-energizing time zone at the terminal of at least one phase A time detection unit for detecting at least one of a set of late falling time from the time when the induced voltage reaches the intermediate level value to the end point of the non-energization time zone;
An advance angle determination unit that determines a magnitude relationship between the rising early period time and the rising late period time, and a magnitude relation between the falling early period time and the falling late time;
A drive device for a sensorless brushless motor, comprising: an advance angle adjusting unit that adjusts the advance angle based on a determination result of the at least one phase relationship of the at least one phase.

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