JP4291660B2 - Brushless motor - Google Patents

Description

  The present invention relates to a brushless motor, and more particularly to optimization of drive control for detecting and driving a rotational position of a magnet rotor.

  A brushless motor is known as a motor without a brush and a commutator. This brushless motor is suitable for long-term driving because the brushed motor is in contact with the commutator and the brush is free from frictional wear. For this reason, it is widely used in environments where the frequency of use is high and maintenance is not performed regularly, such as water pumps for cooling vehicles and drive motors for various home appliances.

  The brushless motor is composed of an armature winding and a magnet rotor, and is driven while detecting the rotational position of the magnet rotor. That is, the rotational position of the magnet rotor is detected, an appropriate phase correction is performed on the detected rotational position information, and a drive signal is output based on the rotational position information after the phase correction. The armature winding generates a rotating magnetic field when receiving a drive signal, and the magnet rotor rotates by receiving torque from the generated rotating magnetic field.

  Here, Patent Document 1 discloses a technique for performing phase correction optimum for detected rotational position information in a brushless motor that detects and drives the rotational position of a magnet rotor.

  As shown in FIG. 8, the rotor position detection circuit 100 detects the rotation position of the magnet rotor 102 and outputs a rotation position signal to the phase correction unit 106 of the microcomputer 104. The phase correction unit 106 calculates a correction amount for phase correction from a phase correction map 108 stored in a memory (not shown) based on the rotation speed of the magnet rotor 102 detected from the rotation position signal, and uses the calculated correction amount as the energization timing. Output to the generation unit 110. The energization timing generation unit 110 performs phase correction of the correction amount on the rotation position signal and outputs an energization switching timing signal to the energization switching logic control unit 112. The energization switching logic control unit 112 outputs a drive signal for controlling the inverter circuit 114 to the inverter circuit 114 based on the energization switching timing signal. Based on the drive signal, the inverter circuit 114 energizes the armature winding 122 with a power source (not shown) to generate a rotating magnetic field and drive the brushless motor 120.

  The phase correction map 108 stores a correction amount corresponding to the rotational speed, and the correction amount is calculated based on the rotational speed. However, there may be variations in motor characteristics, the power supply voltage used during driving and the power supply voltage used when setting the phase correction map 108 may differ, and a phase correction map 108 in which an optimal correction amount is set for various conditions is prepared. This is virtually impossible due to memory capacity limitations.

  Therefore, in order to drive the brushless motor 120 efficiently, the correction amount is corrected to an optimal value as follows according to the driving condition.

The current detection circuit 116 detects the current (motor current) of the brushless motor 120, detects a minute change in the motor current, and outputs the current value as a detection signal to the correction amount correction direction determination unit 118 of the microcomputer 104. The correction amount correction direction determination unit 118 periodically slightly changes the correction amount calculated from the phase correction map 108 in the phase correction unit 106 in the increase / decrease direction, and based on the detection signal, the magnitude of the current value due to the small change in the correction amount is changed. A change is detected, and an increase / decrease direction (correction direction) for correcting the correction amount is determined. That is, when the brushless motor 120 is rotating at a constant rotation speed, the smaller the current value of the motor current, the lower the power consumption and the higher the efficiency. Therefore, the current value decreases due to a minute change in the correction amount. The increase / decrease direction is determined as the correction direction. The phase correction unit 106 corrects the correction amount in the correction direction determined by the correction amount correction direction determination unit 118 (phase correction optimization).
JP 2000-209888 A

  However, in the case of the brushless motor 120 in which load fluctuation occurs like a water pump, even if the correction amount is corrected in the correction direction in which the current value decreases, the efficiency is not necessarily improved. The reason is that when a load change occurs during the phase correction optimization, the torque required for the rotation changes, and the motor current also changes to generate the torque. That is, even if the current value decreases, it is impossible to determine whether the efficiency is improved and the current value is decreased or whether the current value is decreased due to load fluctuation.

  Also, during the phase correction optimization, it is required to keep the rotation speed constant, but it is theoretically possible that the rotation speed does not change, but it is not practical. If the efficiency is improved by a minute change in the correction amount, the rotation speed slightly increases. As the rotation speed slightly increases, the load on the brushless motor 120 increases slightly. As a result, there are cases where the current value increases even when the correction amount is changed in the direction of improving efficiency.

  Therefore, in the determination based on the current value, the correction direction of the correction amount may not be appropriate, and as a result of the phase correction optimization, the energization switching may be performed at an inefficient timing.

  In view of the above facts, an object of the present invention is to provide a brushless motor that efficiently corrects a correction amount for correcting the phase of a rotational position signal even when a load change occurs, and corrects the correction direction without making a mistake.

In order to solve the above-described problem, the invention according to claim 1 is configured such that each phase of a plurality of armature windings is controlled to turn on / off each other, whereby a rotating magnetic field is applied to the armature winding. In a brushless motor for generating and rotating the magnet rotor, phase correction amount calculating means for detecting a rotation position information of the magnet rotor and obtaining a correction amount for phase correction of the rotation position information; and Energization switching control means for performing phase correction of the correction amount, calculating timing for mutually controlling on / off of energization in each phase of the armature winding, and controlling the energization of the armature winding, and the magnet Detection means for detecting an induced voltage generated in a specific phase of the armature winding due to rotation of the rotor, and timing within an energization off period before and after the energization on period when energization to the specific phase is on. The current-on period 1/2 timing at a timing with a symmetry axis, respectively a phase shift detection means for detecting a phase shift from the potential difference of the induced voltage is detected, the deviation amount of the detected phase by the phase shift detection means by said detecting means Correction amount correction means for correcting the correction amount so that the induced voltage generated during the off period before and after the energization on period is symmetric using a larger correction amount as And

  According to the first aspect of the present invention, the brushless motor generates a rotating magnetic field in the armature winding by mutually controlling on / off of energization of each phase of the armature winding, and the magnet is generated by the rotating magnetic field. The rotor is driven to rotate. When the brushless motor is driven, an induced voltage is generated in the armature winding due to the rotation of the magnet rotor.

  The phase correction amount calculation means detects the rotational position information of the magnet rotor, obtains the rotational speed from the detected rotational position information, and calculates a correction amount for phase correction of the rotational position information, for example, using a phase correction map.

  The energization switching control means performs phase correction of the correction amount calculated by the phase correction amount calculation means on the rotational position information, and timing for mutually controlling on / off of energization in each phase of the armature winding (energization switching timing) To control the energization of the armature winding.

On the other hand, the detecting means detects an induced voltage generated in a specific phase of the armature winding by rotating the magnet rotor.
The phase shift detection means is the timing within the energization off period before and after the energization on period when energization to a specific phase is on, and at the timing with the half time of the energization on period as the axis of symmetry. The phase shift is detected from the potential difference between the induced voltages detected by the means . This is because when the armature winding is energized at the ideal energization switching timing and the brushless motor is driven most efficiently, the waveform of the induced voltage generated during the energization off period before and after the energization on period is symmetric. It is based on becoming.

  For example, when the brushless motor is driven at an ideal energization switching timing in 120 ° square wave energization, as shown in FIG. 7A, before and after the energization on period (see period t18 in FIG. 7A). The waveform of the induced voltage generated during the energization off period (see periods t16 and t17 in FIG. 7A) is symmetric. On the other hand, when driven at a non-ideal energization switching timing, as shown in FIG. 7B, the waveform of the induced voltage generated before and after the energization on period (see period t19 in FIG. 7B) (FIG. The periods t20 and t21 of B) are not symmetrical.

  Therefore, it can be determined from the symmetry of the induced voltage whether the brushless motor is driven efficiently.

  The correction amount correction means corrects the correction amount based on the detection result of the phase shift detection means so that the induced voltages generated during the off period before and after the energization on period are symmetric.

  Therefore, according to the first aspect of the invention, the phase correction correction amount is corrected to the ideal energization switching timing by detecting a phase shift from the induced voltage generated in the energization off period before and after the energization on period. Thus, the brushless motor can be driven efficiently.

That is, according to the first aspect of the present invention, when energization is turned off, energization is turned on, and energization is switched off, energization is generated in the energization off period before and after the energization on period with the ½ axis as the symmetry axis. The phase shift can be detected by detecting the induced voltage to be detected and comparing the detected induced voltages.

  In a brushless motor driven at an ideal energization switching timing, this occurs during the energization off period when the half period of the energization on period is a symmetric axis (see the symmetric axis in FIG. 7A). Since the induced voltage (see periods t16 and t17 in FIG. 7A) is symmetric, a phase shift can be detected from the detected induced voltage.

Therefore, according to the first aspect of the present invention, it is possible to detect a phase shift from the ideal energization switching timing by comparing the induced voltages with the ½ axis as the axis of symmetry when the energization is turned on. it can.

The invention according to claim 2, in the invention of claim 1 Symbol placement, the armature winding further comprises a pulse width modulation means for generating a rotating magnetic field which is pulse width modulated, said phase shift detection means, energizing When the induced voltage generated in the off period cannot be detected by pulse width modulation, the induced voltage generated at a timing that is a positive or negative integer multiple of the electrical angle of 360 ° is detected from the timing at which the induced voltage is not detected. It is characterized by detecting a shift of the distance.

According to the invention of claim 2 , the voltage generated in the armature winding by the pulse width modulation means vibrates by the pulse width modulation, and the armature winding has a period in which the induced voltage is exposed and a period in which the induced voltage is not exposed. .

  The phase shift detection means detects the induced voltage generated in a specific phase of the armature winding, but if the induced voltage is not exposed at the detected timing, the phase shift cannot be detected. Induced voltage generated at a timing that is a negative integer multiple of electrical angle 360 ° (before integer multiple of electrical angle 360 °) or a positive integer multiple of electrical angle 360 ° (after integer multiple of electrical angle 360 °) Is detected, and the phase shift is detected again.

  Thereby, an induced voltage can be acquired more reliably and a phase shift can be detected.

Therefore, according to the second aspect of the present invention, even if the induced voltage generated in the armature winding is not exposed by the pulse width modulation means, the phase shift can be detected stably.

According to a third aspect of the present invention, in the first or second aspect of the invention, the phase correction amount calculating means detects a pole change point of the magnet rotor by a Hall element to obtain rotational position information. Features.

According to the invention of claim 3 , the rotational position information detecting means detects the rotational position information by detecting the pole change point of the magnet rotor rotating by the Hall element.

  Since the Hall element is inexpensive, it is widely used as a means for detecting rotational position information of a brushless motor.

  However, in the detection of the rotational position of the magnet rotor by the Hall element, high accuracy is required for the mounting position of the Hall element, and an error occurs in the rotational position information detected by the mounting position of the Hall element.

Therefore, by using the invention of claim 1 or claim 2 Symbol placement, even if there is an error in the rotational position information by the mounting position of the Hall element, it detects an error by the phase shift detection means, the correction amount correcting means Since it can be corrected to an ideal energization switching timing, the brushless motor can be driven efficiently.

Therefore, according to the invention of claim 3 , even if there is an error in the rotational position information depending on the mounting position of the Hall element, the error can be corrected by the correction amount correcting means and the drive can be efficiently performed.

(First embodiment)
The first embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a brushless motor 50 and a brushless motor driving apparatus 10 according to the first embodiment.

  The brushless motor 50 includes a magnet rotor 54 and a three-phase armature winding 52 in which U, V, and W armature windings are star-connected.

  The brushless motor drive device 10 is connected to a power source (not shown), and rotates by detecting the rotational position of an inverter circuit 14 that switches a power supply to a three-phase armature winding 52 in response to a drive signal that will be described later, and a magnet rotor 54. A rotor position detection circuit 16 that outputs a position signal, a terminal voltage detection circuit 18 that detects a voltage generated in the U phase of the three-phase armature winding 52 and outputs a terminal voltage signal, a rotation position signal and a terminal voltage The microcomputer 20 is configured to receive a signal and output a drive signal to the inverter circuit 14.

  Further, the microcomputer 20 calculates a correction amount for phase correction from a phase correction map 24 described later based on the rotational position signal, corrects the correction amount based on a correction direction determination signal described later, and outputs a correction amount signal. An energization timing generation unit 26 that performs phase correction of the correction amount on the rotation position signal based on the correction amount signal based on the correction amount signal and outputs an energization switching timing signal, and an energization switching that outputs a drive signal based on the energization switching timing signal A logic control unit 28, a phase shift detection unit 30 that detects a phase shift based on the terminal voltage signal and outputs a phase shift detection signal, and a correction direction that corrects the correction amount of the phase correction based on the phase shift detection signal And a correction amount correction direction determination unit 32 that outputs a correction direction determination signal to the phase correction unit 22, and a CPU, RAM, and ROM (not shown) It is configured to include a bus for connecting these. The ROM also stores a phase correction map 24.

  Each phase of the three-phase armature winding 52 is connected to the output terminal of the inverter circuit 14 and the rotor position detection circuit 16, and the U phase is connected to the terminal voltage detection circuit 18. The three-phase armature winding 52 is switched in energization by a drive signal to generate a rotating magnetic field of 120 ° square wave energization.

  The magnet rotor 54 rotates by receiving torque from the rotating magnetic field generated in the three-phase armature winding 52. In addition, when the magnet rotor 54 rotates, an induced voltage is generated in each phase of the three-phase armature winding 52.

  The inverter circuit 14 is composed of a circuit in which three pairs (a total of six) switching elements U +, U−, V +, V−, W +, and W− are connected in a three-phase bridge, and the switching elements U +, V +, and W + The upper energization is turned on, and the lower energization is turned on by U−, V−, and W−. The inverter circuit 14 is connected to a power source (not shown), the energization switching logic control unit 28, and each phase of the three-phase armature winding 52, receives a drive signal from the energization switching logic control unit 28, and the three-phase armature winding 52. Next, energization switching of 120 ° square wave energization is performed. Further, one end side of the switching elements U−, V−, and W− is GND.

  The rotor position detection circuit 16 is connected to each phase of the three-phase armature winding 52 and the phase correction unit 22, and extracts a pseudo induced voltage from the terminal voltage of the three-phase armature winding 52 through a low-pass filter. The zero cross point of the induced voltage is detected and output to the phase correction unit 22 as a rotational position signal.

  The terminal voltage detection circuit 18 is connected to the U phase of the three-phase armature winding 52 and the phase shift detection unit 30, and detects the voltage generated in the U phase of the three-phase armature winding 52 to detect the terminal voltage. The signal is output to the phase shift detector 30.

  The phase correction unit 22 is connected to the rotor position detection circuit 16, the phase correction map 24, the energization timing generation unit 26, and the correction amount correction direction determination unit 32, and detects the rotation speed of the magnet rotor 54 from the rotation position signal. Based on the rotation speed, a correction amount for phase correction is calculated from the phase correction map 24.

  In addition, a correction direction determination signal is received from a correction amount correction direction determination unit 32 described later, and the calculated correction amount is corrected in the correction direction. The corrected correction amount and the rotational position signal are output to the energization timing generation unit 26 as a correction amount signal.

  The phase correction map 24 is connected to the phase correction unit 22, and a correction amount for performing phase correction is mapped to the rotational position signal on condition of the rotational speed of the magnet rotor 54, and is stored in a ROM (not shown).

  The energization timing generation unit 26 is connected to the phase correction unit 22 and the energization switching logic control unit 28, receives a correction amount signal from the phase correction unit 22, performs phase correction of the correction amount on the rotational position signal, and a three-phase armature The timing for switching energization to the winding 52 (energization switching timing) is output as an energization switching timing signal.

  The energization switching logic control unit 28 is connected to the energization timing generation unit 26 and the inverter circuit 14 and outputs a drive signal based on the energization switching timing signal.

  The phase shift detection unit 30 is connected to the terminal voltage detection circuit 18 and the correction amount correction direction determination unit 32, receives a terminal voltage signal from the terminal voltage detection circuit 18, detects an induced voltage at a predetermined timing, and detects the detected induced voltage. The phase shift is detected and a phase shift detection signal is output.

  The correction amount correction direction determination unit 32 is connected to the phase correction unit 22 and the phase shift detection unit 30, determines the correction direction of the correction amount of the phase correction based on the phase shift detected by the phase shift detection unit 30, and the correction direction. The determination signal is output to the phase correction unit 22.

  Next, the operation of the first embodiment will be described.

  Since the rotation position of the magnet rotor 54 is detected by the rotor position detection circuit 16 and the drive signal is output from the energization switching logic control unit 28 based on the detected rotation position signal, the description is omitted. To do.

  In each phase of the three-phase armature winding 52, the energization on at an electrical angle of 120 ° and the energization off at an electrical angle of 60 ° are repeated by a drive signal of 120 ° square wave energization. The magnet rotor 54 is rotated by a rotating magnetic field generated in the magnetic field.

  When the magnet rotor 54 is rotating, the U-phase of the three-phase armature winding 52 has a voltage generated by a drive signal (see drive signals U + and U- in FIG. 2) and reverse of self-induction as shown in FIG. An electromotive voltage and an induced voltage (see the induced voltage in FIG. 2) are generated.

  The terminal voltage detection circuit 18 detects the U-phase voltage of the three-phase armature winding 52 and outputs a terminal voltage signal to the phase shift detection unit 30.

  The phase shift detector 30 detects the induced voltage from the terminal voltage signal at the following timing.

  An electrical angle 120 at which energization is turned on when energization is switched by energization off (see period t1 in FIG. 2), energization on (see period t2 in FIG. 2), energization off (see period t3 in FIG. 2) by the drive signal. The induced voltage VF1 generated at an electrical angle of 90 ° before (period t6 in FIG. 2) and after (period t7 in FIG. 2) with the phase 1/2 detection symmetrical axis as a phase deviation detection symmetrical axis. VF2 is detected. Then, the detected voltages VF1 and VF2 are compared to detect a phase shift.

  In the case shown in FIG. 2, the induced voltages VF1 and VF2 are equal and are ideal energization switching timings. Therefore, no phase shift is detected, and a phase shift detection signal without phase shift is detected as a correction amount correction direction determination unit. The correction amount correction direction determination unit 32 outputs the correction direction determination signal without correction to the phase correction unit 22.

  When receiving the correction direction determination signal without correction, the phase correction unit 22 outputs the correction amount calculated from the phase correction map 24 to the energization timing generation unit 26 as it is.

  The energization timing generation unit 26 performs phase correction of the correction amount on the rotational position signal and outputs an energization switching timing signal to the energization switching logic control unit 28. In the energization switching logic control unit 28, a drive signal is output based on the energization switching timing signal, and the magnet rotor 54 rotates.

  On the other hand, when a voltage as shown in FIG. 3 is generated in the U phase of the three-phase armature winding 52, the phase shift detection unit 30 turns on the current from the terminal voltage signal (see t10 in FIG. 3). Is induced at an electrical angle of 90 ° before (see t11 in FIG. 3) and after (see t12 in FIG. 3) with a phase shift detection symmetric axis (see phase shift detection symmetric axis in FIG. 3). The voltages VF3 and VF4 are detected, and the detected induced voltages VF3 and VF4 are compared. As a result of the comparison, the voltages VF3 and VF4 do not match, and therefore a phase shift detection signal with a phase shift is output to the correction amount correction direction determination unit 32.

  When the correction amount correction direction determination unit 32 receives a phase shift detection signal with a phase shift, it compares the induced voltages VF3 and VF4 to determine the correction direction of the correction amount of the phase correction.

  In the case shown in FIG. 3, since VF3 <VF4, it is determined that the correction amount of the phase correction needs to be reduced, and the phase correction unit 22 is instructed to correct the correction amount in the direction of reducing the correction amount (the direction of arrow A in FIG. 3). Is output as a correction direction determination signal.

  This is because the symmetry axis in which the induced voltage is symmetric (see the induced voltage symmetry axis in FIG. 3) is the symmetric axis that is the ideal energization switching timing, so the correction amount is reduced and the symmetry in which the induced voltage is symmetric. This is because the axis and the phase shift detection symmetry axis are corrected to coincide with each other.

  The phase correction unit 22 performs correction by reducing the correction amount of the phase correction by a certain value based on the correction direction determination signal, and outputs the corrected correction amount to the energization timing generation unit 26 as a correction amount signal. This constant value is an appropriate value that has little influence on the driving of the brushless motor 50.

  The energization timing generation unit 26 outputs an energization switching timing signal based on the corrected correction amount and the rotational position signal, and the energization switching logic control unit 28 outputs a signal drive signal based on the energization switching timing signal to rotate the magnet. The child 54 rotates.

  By reducing the correction amount of the phase correction by a certain value, the difference (phase shift) between the phase shift detection symmetry axis and the symmetry axis where the induced electromotive force voltage is symmetric is reduced, and the induced electromotive force voltage VF3, The potential difference from VF4 is also reduced.

  When the brushless motor 50 is driven, the phase shift converges by repeating the process of detecting the phase shift and correcting the correction amount to a constant value, and the energization switching timing is set to the ideal energization switching timing. It can be corrected.

  In addition, by determining the phase shift from the symmetry of the induced voltage, the correction direction of the correction amount is not mistaken even if the torque required for rotation changes due to load fluctuation.

  As described above, according to the brushless motor of the first embodiment, the symmetry of the induced voltage generated in the energization off period before and after the energization on period, with 1/2 phase of the energization on period as the phase shift detection symmetry axis. Thus, a brushless motor that can be driven efficiently can be provided without detecting the correction direction of the correction amount for correcting the phase of the rotational position signal even if a load change occurs.

  Here, the phase shift detection unit 30 detects the induced voltage with the half period of the energization ON period as the phase shift detection symmetry axis, but changes from energization ON to OFF (see arrows t4 and t5 in FIG. 2). It is also possible to detect the phase shift by detecting the induced voltage (see VF1 and VF2 in FIG. 2) generated after the second and comparing the induced voltages.

  In the first embodiment, the phase shift is detected from the induced voltage at the timing of the electrical angle of 90 ° from the phase shift detection symmetric axis from the phase shift detection symmetric axis, but the detection timing is symmetric with respect to the phase shift detection symmetric axis. In addition, any timing may be used as long as the induced voltage can be detected.

Although the correction amount for correcting the correction amount is a constant value, the correction amount may be calculated from the magnitude of the phase shift and corrected. By increasing or decreasing the correction value according to the magnitude of the phase shift, the phase shift can be quickly converged.
(Second Embodiment)
Next, a second embodiment of the present invention will be described. The feature of the second embodiment is that there are a period in which the induced voltage is exposed to the three-phase armature winding 52 and a period in which the induced voltage is not exposed to the three-phase armature winding 52 by pulse width modulation. The induced voltage is exposed at the timing of detecting the induced voltage. If not, the detection timing is changed to a timing that is an integral multiple of positive and negative electrical angles of 360 °.

  FIG. 4 is a schematic configuration diagram of the brushless motor 50 and the brushless motor driving apparatus 10 according to the second embodiment. In addition, since the part of the same code | symbol is the structure similar to 1st Embodiment, description is abbreviate | omitted.

  The brushless motor driving apparatus 10 according to the second embodiment has a pulse width modulation circuit 34 in addition to the configuration of the first embodiment.

  The pulse width modulation circuit 34 is connected to the inverter circuit 14 and the energization switching logic control unit 28, performs pulse width modulation on the drive signal output from the energization switching logic control unit 28, and outputs the drive signal to the inverter circuit 14. Since the drive signal is subjected to pulse width modulation by the pulse width modulation circuit 34, the voltage generated in the three-phase armature winding 52 is oscillating (see FIGS. 5 and 6), and the induced voltage is also oscillating. There is a period (see period t9 in FIG. 5) in which the induced voltage is not exposed depending on the detection timing.

  The phase shift detector 30 detects the induced voltage (see period t8 in FIG. 5) exposed at a predetermined timing from the voltage generated in the U phase of the three-phase armature winding 52, and the induced voltage is exposed. If not, the induced voltage generated after a positive integer multiple of the electrical angle of 360 ° is detected again, a phase shift is detected from the detected induced voltage, and a phase shift detection signal is output.

  Next, the operation of the second embodiment will be described.

  When the magnet rotor 54 is rotated by the drive signal modulated by the pulse width modulation circuit 34, a voltage as shown in FIGS. 5 and 6 is generated in the U phase of the three-phase armature winding 52. Yes.

  The terminal voltage detection circuit 18 detects the U-phase voltage of the three-phase armature winding 52 and outputs a terminal voltage signal.

  The phase shift detection unit 30 uses the phase shift detection symmetry axis as a phase shift detection symmetry axis at a half time of an electrical angle of 120 °, which is energized from the U-phase voltage of the three-phase armature winding 52 based on the terminal voltage signal. Voltages VF5 and VF6 that are generated 90 degrees before (period t13 in FIG. 5) and after (period t14 in FIG. 5) are detected. However, as shown in FIG. 5, the induced voltage is not exposed at the timing when VF6 is detected. In this case, the induced voltage VF7 exposed at a timing after an electrical angle of 360 ° (one cycle) (see period t15 in FIG. 6) from the timing at which VF6 is detected is detected.

  Here, if the induced voltage is not further exposed at the timing when VF7 is detected, the induced voltage exposed at the timing that is after the electrical angle 720 ° (a positive integer multiple of 360 °) from the timing when VF6 is detected. Is detected.

  As described in the first embodiment, the phase shift detection unit 30 compares the detected voltages VF5 and VF7 to detect a phase shift. The correction amount correction direction determination unit 32 compares the induced voltages VF5 and VF7 to obtain the correction direction of the correction amount for phase correction.

  Thus, according to the brushless motor of the second embodiment, the drive signal is subjected to pulse width modulation, so that even if the induced voltage is not exposed at the timing of detecting the induced voltage, the electrical angle is 360 °. By detecting the induced voltage exposed at an integral multiple of timing, it is possible to reliably detect a phase shift.

  In the second embodiment, the voltage VF6 generated 90 degrees after the electrical angle of the phase shift detection symmetric axis is taken as an example. However, the voltage VF5 generated 90 degrees before the electrical angle of the phase shift detection symmetric axis is also used. When the induced voltage is not exposed at the detection timing, it is possible to detect the induced voltage exposed at a timing that is an integral multiple of the electrical angle of 360 °.

  When the induced voltage is not exposed, the exposed induced voltage was detected at a timing that is an integer multiple of the electrical angle 360 ° (a positive integer multiple), but before the integer multiple of the electrical angle 360 ° (a negative integer multiple). The induced voltage at the timing may be stored in the RAM, and the phase shift may be detected.

  In the first and second embodiments, the rotor position detection circuit 16 extracts the pseudo induced voltage from the terminal voltage of the armature winding 52 through a low-pass filter, and detects the zero cross point of the pseudo induced voltage. 9, the Hall element 36 is provided along the rotation direction of the magnet rotor 54, and the Hall voltage generated in the Hall element 36 by the magnetic field of the magnet rotor 54 is changed to the Hall voltage as shown in FIG. It may be detected by the detection circuit 38 and a rotational position signal may be output based on the extreme change point of the Hall voltage. In the detection of the rotational position signal based on the pole change point, an error (phase shift) occurs in the rotational position signal depending on the mounting position of the Hall element 36. The phase shift detection unit 30 and the correction amount correction direction determination unit 32 The brushless motor 50 can be driven efficiently by detecting a phase shift from the induced voltage generated in the U phase of the child winding 52 and correcting the correction amount.

It is a schematic block diagram of the brushless motor and brushless motor drive device concerning a 1st embodiment. It is a wave form diagram of the voltage and drive signal without the phase shift which generate | occur | produce in the 3-phase armature winding U phase which concerns on 1st Embodiment. It is a wave form diagram of a voltage and a drive signal with a phase gap which occur in a three-phase armature winding U phase concerning a 1st embodiment. It is a schematic block diagram of the brushless motor and brushless motor drive device which concern on 2nd Embodiment. It is a voltage waveform figure by which the pulse width modulation which generate | occur | produces in the three-phase armature winding U phase which concerns on 2nd Embodiment. FIG. 6 is a voltage waveform diagram when the voltage detection timing is delayed by an electrical angle of 360 ° in FIG. 5 according to the second embodiment. It is a waveform diagram of ideal energization timing. It is a schematic block diagram of the conventional brushless motor and a brushless motor drive device. It is a schematic block diagram of the brushless motor and brushless motor drive device which detect a rotation position signal with the Hall element concerning a 1st embodiment.

Explanation of symbols

10 brushless motor drive device, 14 inverter circuit, 16 rotor position detection circuit, 18 terminal voltage detection circuit, 20 microcomputer, 22 phase correction unit, 24 phase correction map, 26 energization timing generation unit, 28 energization switching logic control unit, 30 phase shift detection unit, 32 correction amount correction direction determination unit, 34 pulse width modulation circuit, 36 hall element, 38 hall voltage detection circuit, 50 brushless motor, 52 three-phase armature winding, 54 magnet rotor

Claims (3)

In the brushless motor that generates a rotating magnetic field in the armature winding and rotates the magnet rotor by mutually controlling on / off of energization of each phase of the multi-phase armature winding,
Phase correction amount calculating means for detecting rotational position information of the magnet rotor and obtaining a correction amount for phase correction of the rotational position information;
Energization switching for performing phase correction of the correction amount on the rotational position information, calculating timing for mutually controlling on / off of energization in each phase of the armature winding, and controlling energization of the armature winding Control means;
Detecting means for detecting an induced voltage generated in a specific phase of the armature winding by rotation of the magnet rotor;
Detected by the detection means at timings within the energization-off period before and after the energization-on period when energization to the specific phase is on, with a half-axis timing of the energization-on period as the axis of symmetry. Phase shift detection means for detecting a phase shift from the potential difference of the induced voltage ,
The correction amount is set so that the induced voltage generated during the OFF period before and after the energization ON period is symmetric using a larger correction amount as the phase shift amount detected by the phase shift detection unit is larger. Correction amount correcting means for correcting;
A brushless motor characterized by comprising: Pulse width modulation means for generating a pulse magnetic field-rotating magnetic field in the armature winding;
When the induced voltage generated during the energization-off period cannot be detected by pulse width modulation, the phase shift detection means is generated at a timing that is a positive or negative integer multiple of an electrical angle of 360 ° from the timing at which it was not detected. brushless motor of claim 1, wherein said to detect the induced voltage. The phase correction amount calculating means, said claim 1 or claim 2 Symbol placement of the brushless motor is characterized in that by detecting the pole change point of the magnet rotor by a Hall element determining the rotational position information.

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