JP4506730B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor using a permanent magnet and an electromagnetic coil.

  As an electric motor using a permanent magnet and an electromagnetic coil, for example, one described in Patent Document 1 below is known.

JP 2001-298882 A

  In this conventional electric motor, control is performed using an on / off signal from a digital magnetic sensor. Specifically, the timing of polarity reversal of the voltage applied to the electromagnetic coil is determined using an on / off signal of the digital magnetic sensor.

  Some magnetic sensors have analog outputs (so-called analog magnetic sensors). However, when an analog magnetic sensor is used for motor control, due to various manufacturing errors of the motor, a considerable error occurs in the sensor output, and good motor control may not be performed. . The manufacturing errors of the motor that affect the output of the analog magnetic sensor include, for example, an error in the installation position of the magnetic sensor, an error in the boundary position between the N pole and the S pole due to the magnetization error of the permanent magnet, There is an error in the mounting position of the element portion. However, in the past, the actual situation is that there has not been a sufficient device for realizing accurate motor control using an analog magnetic sensor in consideration of these errors. Such a problem is not limited to the case of using an analog magnetic sensor, but is a problem common to the case of using a digital magnetic sensor having a multi-valued analog output.

  It is an object of the present invention to provide a technique that realizes accurate motor control while considering an error related to the output of a magnetic sensor.

In order to achieve the above object, an electric motor according to the present invention provides:
A stator including a coil array having a plurality of electromagnetic coils;
A rotor comprising a magnet array having a plurality of permanent magnets;
A plurality of magnetic sensors that output an output signal indicating an analog change according to the relative positions of the magnet array and the coil array;
A drive control circuit that generates an applied voltage to the coil array using an analog change in output signals of the plurality of magnetic sensors;
An output waveform correction unit that respectively performs gain correction and offset correction of the output signals of the plurality of magnetic sensors so that the output signals of the plurality of magnetic sensors at the time of operation of the electric motor each have a predetermined waveform shape;
A correction value setting unit for setting a correction value for waveform correction in the output waveform correction unit;
With
The output waveform correction unit has a memory for storing a gain correction value and an offset correction value ,
An identification ID code is assigned to each of the plurality of magnetic sensors,
The correction value setting unit measures the peak voltage of the output signal of each magnetic sensor a plurality of times while the rotor continues to rotate, and calculates the average value or the maximum value of the peak voltage in the plurality of measurements. The gain correction value is determined as a gain correction value, and the gain correction value of each magnetic sensor is transmitted to the output waveform correction unit together with the ID code of each magnetic sensor and stored in the memory .

Since this electric motor includes an output waveform correction unit that performs correction so that the output signal of the magnetic sensor has a predetermined waveform shape, the drive control circuit uses an analog change in the output signal of the magnetic sensor. An applied voltage having a desired waveform can be applied to the coil array. As a result, accurate motor control can be realized even if an error occurs in the output of the magnetic sensor. In addition, since the plurality of magnetic sensors are distinguished from each other by the ID code, and the output waveform correction value is received from the outside together with the ID code, it is possible to correct the waveforms of the output signals of the plurality of magnetic sensors to each desired one. is there. Further, if gain correction and offset correction are used, the output signal of the magnetic sensor can be easily corrected to a desired waveform shape. In particular, in gain correction, gain correction is performed using an average value or maximum value of peak voltages in a plurality of measurements, so that the most preferable gain can be set for the entire plurality of magnets.

The correction value setting unit measures the maximum voltage and the minimum voltage of the output signal of each magnetic sensor while the rotor continues to rotate, and calculates the average value of the maximum voltage and the minimum voltage as the offset correction value of the magnetic sensor. The offset correction value may be transmitted to the output waveform correction unit together with the gain correction value and the ID code of each magnetic sensor and stored in the memory .

  The present invention can be realized in various forms. For example, the present invention can be realized in the form of an electric motor and a control method thereof, a correction method and apparatus for a sensor of the electric motor, an actuator using the same, and the like. it can.

Next, embodiments of the present invention will be described in the following order.
A. Configuration of electric motor:
B. Configuration of drive control circuit:
C. Sensor output correction:
D. Other embodiments of the drive control circuit:
E. Other implementation steps for sensor output correction:
F. Variations:

A. Configuration of electric motor:
FIG. 1A is a cross-sectional view showing a configuration of a motor body of an electric motor as one embodiment of the present invention. The motor main body 100 includes a substantially disc-shaped stator portion 10 and a rotor portion 30. The rotor unit 30 has a magnet row 34 </ b> M having a plurality of magnets, and is fixed to the rotating shaft 112. The magnetization direction of the magnet row 34M is the vertical direction. The stator unit 10 includes an A-phase coil group 14 </ b> A disposed at the upper part of the rotor unit 30 and a B-phase coil group 24 </ b> B disposed at the lower part of the rotor unit 30.

  1 (B) to 1 (D) separately show the first coil row 14A of the stator unit 10, the rotor unit 30, and the second coil row 24B of the stator unit 10. FIG. In this example, the A-phase coil group 14A and the B-phase coil group 24B each have six coils, and the magnet group 34M also has six magnets. However, the number of coils and magnets can be set to an arbitrary value.

  FIG. 2A shows the positional relationship between the coil arrays 14A and 24B and the magnet array 34M. The A-phase coil group 14A is fixed to the support member 12A, and the B-phase coil group 24B is fixed to the support member 22B. The A-phase coil array 14A is formed by alternately arranging two types of coils 14A1 and 14A2 excited in opposite directions at a constant pitch Pc. In the state of FIG. 2A, the three coils 14A1 are excited so that the magnetization direction (direction from the N pole to the S pole) is downward, and the other three coils 14A2 have the magnetization direction upward. Excited to become. The B-phase coil array 24B is also formed by alternately arranging two types of coils 24B1 and 24B2 excited in the opposite directions at a constant pitch Pc. In the present specification, “coil pitch Pc” is defined as the pitch between coils of the A-phase coil array or the pitch between coils of the B-phase coil array.

  The magnet row 34M of the rotor unit 30 is fixed to the support member 32M. The permanent magnets of the magnet row 34M are arranged such that the magnetization direction is in a direction perpendicular to the arrangement direction of the magnet row 34M (the left-right direction in FIG. 2A). The magnets of the magnet row 34M are arranged at a constant magnetic pole pitch Pm. In this example, the magnetic pole pitch Pm is equal to the coil pitch Pc and corresponds to π in electrical angle. The electrical angle 2π is associated with a mechanical angle or distance that moves when the phase of the drive signal supplied to the coil array changes by 2π. In this embodiment, when the phases of the drive signals of the A-phase coil group 14A and the B-phase coil group 24B change by 2π, the magnet group 34M moves by twice the coil pitch Pc.

  The A-phase coil group 14A and the B-phase coil group 24B are arranged at positions different from each other by π / 2 in electrical angle. The A-phase coil 14A and the B-phase coil array 24B differ only in position, and have substantially the same configuration in other points. Therefore, hereinafter, only the A-phase coil array will be described except when particularly necessary in the description of the coil array.

  FIG. 2B shows an example of the waveform of the AC drive signal supplied to the A-phase coil group 14A and the B-phase coil group 24B. Two-phase AC signals are respectively supplied to the A-phase coil group 14A and the B-phase coil group 24B. Further, the phases of the drive signals of the A-phase coil group 14A and the B-phase coil group 24B are shifted from each other by π / 2. The state in FIG. 2A corresponds to a phase zero (or 2π) state.

  As shown in FIG. 2A, the motor body 100 further includes an analog magnetic sensor 16A for the A-phase coil group 14A and an analog magnetic sensor 26B for the B-phase coil group 24B. These are hereinafter referred to as “A phase sensor” and “B phase sensor”. The A-phase sensor 16A is disposed at the center position between the two coils of the A-phase coil array 14A, and the B-phase sensor 26B is disposed at the center position between the two coils of the B-phase coil array 24B. Yes. In the present embodiment, the AC drive signals shown in FIG. 1B are generated using the analog outputs of these sensors 16A and 26B. As these sensors 16A and 26B, for example, Hall IC using the Hall effect can be adopted.

  FIG. 3 is an explanatory diagram illustrating an example of an output waveform of the magnetic sensor. In this example, the A phase sensor output SSA and the B phase sensor output SSB are both sine waves. These sensor outputs have substantially the same waveform shape as the back electromotive force of the A-phase coil 14A and the B-phase coil 24B. The waveform of the counter electromotive force generally depends on the shape of the coil and the positional relationship between the magnet and the coil, but is usually a sine wave or a waveform close to a sine wave.

  By the way, the electric motor functions as an energy conversion device that mutually converts mechanical energy and electrical energy. The back electromotive force of the coil is obtained by converting the mechanical energy of the electric motor into electrical energy. Therefore, when the electrical energy applied to the coil is converted into mechanical energy (that is, when the motor is driven), the motor is driven most efficiently by applying a voltage having the same waveform as the back electromotive force. Is possible. As will be described below, “a voltage having the same waveform as the back electromotive force” means a voltage that generates a current opposite to the back electromotive force.

  FIG. 4 is a schematic diagram showing the relationship between the applied voltage of the coil and the back electromotive force. Here, the coil is simulated by a back electromotive force Ec and a resistance. In this circuit, a voltmeter V is connected in parallel with the applied voltage E1 and the coil. When the voltage E1 is applied to the coil to drive the motor, a back electromotive force Ec is generated in a direction in which a current opposite to the applied voltage E1 flows. When the switch SW is opened while the motor is rotating, the back electromotive force Ec can be measured by the voltmeter V. The polarity of the back electromotive force Ec measured with the switch SW opened is the same polarity as the applied voltage E1 measured with the switch SW closed. In the above description, the phrase “applying a voltage having the same waveform as the back electromotive force” means applying a voltage having the same polarity and waveform as the back electromotive force Ec measured by the voltmeter V. ing.

  As described above, when a motor is driven, the motor can be driven most efficiently by applying a voltage having the same waveform as the back electromotive force. Note that the energy conversion efficiency is relatively low near the middle point of the sinusoidal back electromotive force waveform (near voltage 0), and conversely, the energy conversion efficiency is relatively high near the peak of the back electromotive force waveform. it can. When the motor is driven by applying a voltage having the same waveform as that of the counter electromotive force, a relatively high voltage is applied during a period of high energy conversion efficiency, so that the motor efficiency is improved. On the other hand, for example, when the motor is driven with a simple rectangular wave, a considerable voltage is applied even in the vicinity of the position where the back electromotive force is almost zero (middle point), so that the motor efficiency decreases. In addition, when a voltage is applied in such a period where the energy conversion efficiency is low, there arises a problem that vibration and noise are generated.

  As can be understood from the above description, when the motor is driven by applying a voltage having the same waveform as the back electromotive force, the motor efficiency can be improved, and vibration and noise can be reduced. .

  FIGS. 5A and 5B are diagrams showing a method of connecting two types of coils 14A1 and 14A2 of the A-phase coil array 14A. In the connection method of FIG. 5A, all the coils included in the A-phase coil array 14 </ b> A are connected in series to the drive control circuit 300. On the other hand, in the connection method of FIG. 5 (B), a plurality of sets of series connections including a pair of coils 14A1 and 14A2 are connected in parallel. In any of these connection methods, the two types of coils 14A1 and 14A2 are always magnetized with opposite polarities.

  6 (A) to 6 (D) show the operation of the electric motor of this embodiment. In this example, the state in which the magnet array 34M moves to the right with the passage of time is illustrated with respect to the coil arrays 14A and 24B. It can be understood that the left-right direction in these drawings corresponds to the rotation direction of the rotor unit 30 shown in FIG.

  FIG. 6A shows a state at the timing immediately before the phase is 2π. In addition, the solid line arrow drawn between the coil and the magnet indicates the direction of the attractive force, and the broken line arrow indicates the direction of the repulsive force. In this state, the A-phase coil group 14A does not give a driving force in the operation direction (right direction in the figure) to the magnet group 34M, and a magnetic force acts in a direction to attract the magnet group 34M to the A-phase coil group 14A. Yes. Therefore, it is preferable that the voltage applied to the A-phase coil group 14A is zero at the timing when the phase is 2π. On the other hand, the B-phase coil group 24B gives a driving force in the operation direction to the magnet group 34M. In addition, since the B-phase coil group 24B gives not only an attractive force but also a repulsive force to the magnet group 34M, a vertical direction from the B-phase coil group 24B to the magnet group 34M (a direction perpendicular to the operation direction of the magnet group 34M). The net power of is zero. Therefore, it is preferable that the voltage applied to the B-phase coil group 24B has a peak value at the timing when the phase is 2π.

  As shown in FIG. 6B, the polarity of the A-phase coil group 14A is inverted at the timing when the phase is 2π. FIG. 6B shows a state where the phase is π / 4, and the polarity of the A-phase coil group 14A is reversed from that shown in FIG. In this state, the A-phase coil group 14A and the B-phase coil group 24B give the same driving force in the operation direction of the magnet group 34M. FIG. 6C shows a state immediately before the phase is π / 2. In this state, contrary to the state shown in FIG. 6A, only the A-phase coil group 14A applies a driving force in the operation direction to the magnet group 34M. At the timing when the phase is π / 2, the polarity of the B-phase coil group 24B is reversed to the polarity shown in FIG. FIG. 6D shows a state where the phase is 3π / 4. In this state, the A-phase coil group 14A and the B-phase coil group 24B give the same driving force in the operation direction of the magnet group 34M.

  As can be understood from FIGS. 6A to 6D, the polarity of the A-phase coil group 14A is switched at a timing when each coil of the A-phase coil group 14A faces each magnet of the magnet group 34M. The same applies to the B phase coil array. As a result, a driving force can be almost always generated from all the coils, so that a large torque can be generated.

  Note that the period in which the phase is π to 2π is substantially the same as that in FIGS. However, the polarity of the A-phase coil group 14A is inverted again at the timing of the phase π, and the polarity of the B-phase coil group 24B is inverted again at the timing of the phase 3π / 2.

  As can be understood from the above description, the electric motor of the present embodiment uses the attractive force and repulsive force between the coil arrays 14A and 24B and the magnet array 34M to drive the driving force in the operation direction with respect to the magnet array 34M. Have gained. In particular, in this embodiment, since the coil arrays 14A and 24B are arranged on both sides of the magnet array 34M, the magnetic fluxes on both sides of the magnet array 34M can be used for generating a driving force. Therefore, compared to the case where only one side of the magnet is used for generating the driving force as in the case of a conventional electric motor, it is possible to realize a motor with high efficiency and high torque with high use efficiency of magnetic flux. However, one of the two coil arrays 14A and 24B can be omitted.

  Note that the support members 12A, 22B, and 32M are each preferably made of a non-magnetic material. Also, among the various members of the motor body of the present embodiment, the members other than the electrical wiring including the coil and the sensor, the magnet, the rotating shaft, and the bearing portion thereof are all non-magnetic and non-conductive materials. Preferably it is formed. If the magnetic core is not provided, so-called cogging does not occur, and a smooth and stable operation can be realized. Further, if a yoke for constituting the magnetic circuit is not provided, a so-called iron loss (eddy current loss) is extremely small, and an efficient motor can be realized.

B. Configuration of drive control circuit:
FIG. 7 is a block diagram showing the configuration of the motor drive control circuit of this embodiment. FIG. 7A shows a configuration at the time of sensor waveform calibration, and FIG. 7B shows a configuration at the time of practical use. “Sensor waveform calibration” is synonymous with “correction of sensor output waveform”.

  As shown in FIG. 7A, at the time of calibration, the calibration drive control circuit 200 is connected to the connection portion 90 (connector) of the motor body 100. The drive control circuit 200 includes a power supply circuit 210, a CPU 220, an I / O interface 230, a PWM control unit 240, a driver circuit 250, and a communication unit 260. The power supply circuit 210 supplies power to each circuit in the drive control circuit 200 and the motor main body 100. The CPU 220 controls the operation of the drive control circuit 200 by setting a set value in each circuit in the drive control circuit 200. The I / O interface 230 has a function of receiving the sensor outputs SSA and SSB supplied from the motor main body 100 and supplying them to the CPU 220. The CPU 220 determines whether or not the received sensor outputs SSA and SSB have a desired waveform shape, and determines an offset correction value Poffset and a gain correction value Pgain so as to have a desired waveform shape. This determination method will be described in detail later. Hereinafter, the offset correction value is also simply referred to as “offset”, and the gain correction value is also simply referred to as “gain”.

  The PWM control unit 240 generates a PWM signal for driving the coil. The driver circuit 250 is a bridge circuit for driving the coil. The circuit configuration and operation of the PWM control unit 240 and the driver circuit 250 will be described later. The communication unit 260 has a function of supplying the offset correction value Poffset and the gain correction value Pgain determined by calibration to the sensors 16A and 26B and storing them. The communication unit 260 also has a function of transmitting correction values Poffset and Pgain stored in the sensors 16A and 26B to an external device. In order to distinguish between the correction value for the A-phase sensor 16A and the correction value for the B-phase sensor 26B, the communication unit 260 transmits and receives the ID code (identification signal) of each sensor together with the correction value. If the correction value is transmitted using the ID code as described above, the correction values of a plurality of sensors can be distinguished from each other and transmitted via one communication bus.

  As shown in FIG. 7B, when the motor is practically used, a drive control circuit 300 different from that used during calibration is connected to the connection portion 90 of the motor main body 100. The drive control circuit 300 corresponds to the calibration drive control circuit 200 in which the communication unit 260 is omitted.

  FIG. 8 shows the internal configuration of the driver circuit 250. The A-phase driver circuit 252 is an H-type bridge circuit, and drives the A-phase coil group 14A according to the AC drive signals DRVA1 and DRVA2. A white circle attached to the terminal portion of the block indicating the drive signal is negative logic and indicates that the signal is inverted. In addition, arrows with symbols IA1 and IA2 indicate the directions of currents flowing through the drive signals DRVA1 and DRVA2, respectively. The configuration of the B-phase driver circuit 254 is the same as that of the A-phase driver circuit 252, and currents IB1 and IB2 flow by the AC drive signals DRVB1 and DRVB2.

  FIG. 9 is a block diagram showing the internal configuration of the magnetic sensor 16A used in this embodiment. Since the A-phase sensor 16A and the B-phase sensor 26B have the same configuration, only the A-phase sensor 16A will be described below.

  The magnetic sensor 16A includes a magnetic sensor element 410, an offset correction circuit 420, a gain correction circuit 430, an offset storage unit 440, a gain storage unit 450, an amplifier 460, an ID code recording unit 470, and a communication unit 480. It has. The magnetic sensor element 410 is, for example, a hall element.

  The communication unit 480 communicates with the drive control circuit 200 during calibration (FIG. 7A), and receives the offset correction value Poffset and gain correction value Pgain of the sensor output together with the sensor ID. An ID unique to the sensor is recorded in the ID code recording unit 470 inside the sensor, or an ID is set using an external switch. In the example of FIG. 9, the ID can be set using an external switch 472 such as a dip switch. However, the ID can be recorded or set in the motor by various arbitrary means other than the DIP switch. For example, it is possible to omit the external switch 472 and configure the ID code recording unit 470 with a nonvolatile memory. When the ID supplied from the drive control circuit 200 matches the ID of the ID code recording unit 470, the communication unit 480 stores the offset correction value Poffset and the gain correction value Pgain in the storage units 440 and 450, respectively. . The offset correction circuit 420 and the gain correction circuit 430 correct the output waveform of the magnetic sensor element 410 according to these correction values Poffset and Pgain. The corrected sensor output is amplified by the amplifier 460 and output as the sensor output SSA.

  As can be understood from these descriptions, the circuit elements 420, 430, 440, and 450 in FIG. 9 function as an output waveform correction unit that corrects the output waveform of the sensor 16A. Note that the storage units 440 and 450 are preferably composed of nonvolatile memories.

  FIG. 10 is an explanatory diagram showing the internal configuration and operation of the PWM controller 240 (FIG. 7). The PWM control unit 240 includes a basic clock generation circuit 510, a 1 / N frequency divider 520, a PWM unit 530, a forward / reverse direction value register 540, multipliers 550 and 552, and encoding units 560 and 562. AD converters 570 and 572, a voltage command value register 580, and an excitation interval setting unit 590 are provided.

  The basic clock generation circuit 510 is a circuit that generates a clock signal PCL having a predetermined frequency, and is composed of, for example, a PLL circuit. The frequency divider 520 generates a clock signal SDC having a frequency 1 / N of the clock signal PCL. The value of N is set to a predetermined constant value. The value of N is preset in the frequency divider 520 by the CPU 220 (FIG. 7A). The PWM unit 530 includes clock signals PCL and SDC, multiplication values Ma and Mb supplied from the multipliers 550 and 552, a forward / reverse direction instruction value RI supplied from the forward / reverse direction instruction value register 540, and an encoding unit. AC drive signals DRVA1, DRVA2, DRVB1, DRVB2 (FIG. 8) are generated in accordance with the positive / negative sign signals Pa, Pb supplied from 560, 562 and the excitation interval signals Ea, Eb supplied from the excitation interval setting unit 590. Generate. This operation will be described later.

  In the forward / reverse direction value register 540, a value RI indicating the rotation direction of the motor is set by the CPU 220. In the present embodiment, the motor rotates forward when the forward / reverse direction instruction value RI is at L level, and reverses when it is at H level.

  Other signals Ma, Mb, Pa, Pb, Ea, and Eb supplied to the PWM unit 530 are determined as follows. Note that the multiplier 550, the encoding unit 560, and the AD conversion unit 570 are A-phase circuits, and the multiplier 552, the encoding unit 562, and the AD conversion unit 572 are B-phase circuits. Since the operation of these circuit groups is the same, the operation of the A-phase circuit will be mainly described below.

  The output SSA of the magnetic sensor is supplied to the AD converter 570. The range of the sensor output SSA is, for example, from GND (ground potential) to VDD (power supply voltage), and the middle point (= VDD / 2) is the middle point of the output waveform (point passing through the origin of the sine wave). It is. The AD conversion unit 570 performs AD conversion on the sensor output SSA to generate a digital value of the sensor output. The output range of the AD converter 570 is, for example, FFh to 0h (“h” at the end indicates a hexadecimal number), and the median value 80h corresponds to the middle point of the sensor waveform.

  The encoding unit 560 converts the range of the sensor output value after AD conversion, and sets the middle value of the sensor output value to 0. As a result, the sensor output value Xa generated by the encoding unit 560 takes a value in a predetermined range on the positive side (for example, +127 to 0) and a predetermined range on the negative side (for example, 0 to −128). However, what is supplied from the encoding unit 560 to the multiplier 560 is the absolute value of the sensor output value Xa, and the positive / negative sign is supplied to the PWM unit 530 as the positive / negative code signal Pa.

  Voltage command value register 580 stores voltage command value Ya set by CPU 220. This voltage command value Ya functions as a value for setting the applied voltage of the motor together with an excitation interval signal Ea described later, and takes a value of 0 to 1.0, for example. If the excitation interval signal Ea is set so that the entire excitation interval is set without providing the non-excitation interval, Ya = 0 means that the applied voltage is zero, and Ya = 1.0 is This means that the applied voltage is the maximum value. Multiplier 550 multiplies sensor output value Xa output from encoding unit 560 and voltage command value Ya to produce an integer, and supplies the multiplied value Ma to PWM unit 530.

  FIGS. 10B to 10E show the operation of the PWM unit 530 when the multiplication value Ma takes various values. Here, it is assumed that the entire period is an excitation interval and there is no non-excitation interval. The PWM unit 530 is a circuit that generates one pulse with a duty of Ma / N during one cycle of the clock signal SDC. That is, as shown in FIGS. 10B to 10E, the duty of the pulses of the drive signals DRVA1 and DRVA2 increases as the multiplication value Ma increases. The first drive signal DRVA1 is a signal that generates a pulse only when the sensor output SSA is positive, and the second drive signal DRVA2 is a signal that generates a pulse only when the sensor output SSA is positive. However, these are described together in FIGS. 10 (B) to 10 (E). For convenience, the second drive signal DRVA2 is drawn as a negative pulse.

  FIGS. 11A to 11D are explanatory diagrams showing the correspondence relationship between the waveform of the sensor output and the waveform of the drive signal generated by the PWM unit 530. In the figure, “Hiz” means a high impedance state. As described in FIG. 10, the A-phase drive signals DRVA1 and DRVA2 are generated by PWM control using the analog waveform of the A-phase sensor output SSA as it is. The same applies to the B-phase drive signals DRVB1 and DRVB2. Therefore, it is possible to supply effective voltages indicating level changes corresponding to changes in the sensor outputs SSA and SSB to the A-phase coil and the B-phase coil using these drive signals.

  The PWM unit 530 further outputs a drive signal only in the excitation intervals indicated by the excitation interval signals Ea and Eb supplied from the excitation interval setting unit 590, and outputs a drive signal in intervals other than the excitation interval (non-excitation interval). It is configured not to. FIGS. 11E and 11F show drive signal waveforms when the excitation interval EP and the non-excitation interval NEP are set by the excitation interval signals Ea and Eb. In the excitation interval EP, the drive signal pulses of FIGS. 11C and 11D are generated as they are, and no drive signal pulse is generated in the non-excitation interval NEP. Thus, if the excitation interval EP and the non-excitation interval NEP are set, no voltage is applied to the coil near the middle point of the back electromotive force waveform (that is, near the middle point of the sensor output). It is possible to further improve the efficiency. The excitation interval EP is preferably set to a symmetrical interval centered on the peak of the back electromotive force waveform, and the non-excitation interval NEP is centered on the middle point (center point) of the back electromotive force waveform. It is preferable to set to a symmetrical section.

  As described above, when the voltage command value Ya is set to a value less than 1, the multiplication value Ma becomes smaller in proportion to the voltage command value Ya. Therefore, the effective applied voltage can be adjusted also by the voltage command value Ya.

  As can be understood from the above description, in the motor of this embodiment, it is possible to adjust the applied voltage using both the voltage command value Ya and the excitation interval signal Ea. The same applies to the B phase. The relationship between the desired applied voltage, the voltage command value Ya, and the excitation interval signal Ea is preferably stored in advance in a memory in the drive control circuit 300 as a table. In this way, when the drive control circuit 300 receives a desired applied voltage from the outside, the CPU 220 sets the voltage command value Ya and the excitation interval signal Ea in the PWM control unit 240 according to the control signal. Is possible. Note that it is not necessary to use both the voltage command value Ya and the excitation interval signal Ea to adjust the applied voltage, and only one of them may be used.

  FIG. 12 is a block diagram showing an example of the internal configuration of the PWM unit 530 (FIG. 10). The PWM unit 530 includes counters 531 and 532, EXOR circuits 533 and 534, and drive waveform forming units 535 and 536. The counter 531, EXOR circuit 533, and drive waveform forming unit 535 are A phase circuits, and the counter 532, EXOR circuit 534, and drive waveform forming unit 536 are B phase circuits. These operate as follows.

  FIG. 13 is a timing chart showing the operation of the PWM unit 530 during normal rotation of the motor. In this figure, two clock signals PCL and SDC, forward / reverse direction instruction value RI, excitation interval signal Ea, multiplication value Ma, positive / negative sign signal Pa, count value CM1 in counter 531 and counter 531 The output S1, the output S2 of the EXOR circuit 533, and the output signals DRVA1 and DRVA2 of the drive waveform forming unit 535 are shown. The counter 531 repeats the operation of down-counting the count value CM1 to 0 in synchronization with the clock signal PCL every period of the clock signal SDC. The initial value of the count value CM1 is set to the multiplication value Ma. In FIG. 13, a negative value is also drawn as the multiplication value Ma for convenience of illustration, but the counter 531 uses the absolute value | Ma |. The output S1 of the counter 531 is set to H level when the count value CM1 is not 0, and falls to L level when the count value CM1 becomes 0.

  The EXOR circuit 533 outputs a signal S2 indicating an exclusive OR of the positive / negative sign signal Pa and the forward / reverse direction instruction value RI. When the motor rotates normally, the forward / reverse direction instruction value RI is at the L level. Therefore, the output S2 of the EXOR circuit 533 is the same signal as the positive / negative sign signal Pa. The drive waveform forming unit 535 generates drive signals DRVA1 and DRVA2 from the output S1 of the counter 531 and the output S2 of the EXOR circuit 533. That is, out of the output S1 of the counter 531, the signal during the period in which the output S2 of the EXOR circuit 533 is at the L level is output as the first drive signal DRVA1, and the signal during the period in which the output S2 is at the H level Output as. In the vicinity of the right end of FIG. 13, the excitation interval signal Ea falls to the L level, thereby setting the non-excitation interval NEP. Accordingly, in this non-excitation interval NEP, none of the drive signals DRVA1, DRVA2 is output and the high impedance state is maintained.

  FIG. 14 is a timing chart showing the operation of the PWM unit 530 during motor reverse rotation. During reverse rotation of the motor, the forward / reverse direction instruction value RI is set to H level. As a result, the two drive signals DRVA1 and DRVA2 are interchanged from FIG. 13, and as a result, it can be understood that the motor reverses. The B-phase circuits 532, 534, and 536 of the PWM unit 530 operate in the same manner as described above.

  FIG. 15 is an explanatory diagram showing the internal configuration and operation of the excitation interval setting unit 590. The excitation interval setting unit 590 includes an electronic variable resistor 592, voltage comparators 594, 596, and an OR circuit 598. The resistance value Rv of the electronic variable resistor 592 is set by the CPU 220. Voltages V1 and V2 across the electronic variable resistor 592 are applied to one input terminal of a voltage comparator 594,596. A sensor output SSA is supplied to the other input terminal of the voltage comparators 594 and 596. In FIG. 15, the B-phase circuit is omitted for convenience of illustration. Output signals Sp and Sn of the voltage comparators 594 and 596 are input to the OR circuit 598. The output of the OR circuit 598 is an excitation interval signal Ea for distinguishing between excitation intervals and non-excitation intervals.

  FIG. 15B shows the operation of the excitation interval setting unit 590. Both-end voltages V1 and V2 of the electronic variable resistor 592 are changed by adjusting the resistance value Rv. Specifically, both-end voltages V1 and V2 are set to values having the same difference from the median value (= VDD / 2) of the voltage range. When the sensor output SSA is higher than the first voltage V1, the output Sp of the first voltage comparator 594 becomes H level, while when the sensor output SSA is lower than the second voltage V2, the second voltage V2 is output. The output Sn of the voltage comparator 596 becomes H level. The excitation interval signal Ea is a signal obtained by taking the logical sum of these output signals Sp and Sn. Therefore, as shown in the lower part of FIG. 15B, the excitation interval signal Ea can be used as a signal indicating the excitation interval EP and the non-excitation interval NEP. The excitation interval EP and the non-excitation interval NEP are set by the CPU 220 adjusting the variable resistance value Rv.

C. Sensor output correction:
FIG. 16 is an explanatory diagram showing the contents of offset correction of the sensor output. FIG. 16A shows a desirable output waveform SSideal of the sensor output. FIG. 16B shows an example of the sensor output SSup shifted upward from the desired sensor output SSideal and the sensor output SSdown shifted downward. In such a case, a waveform close to the desired sensor output SSideal can be corrected by adding a vertical offset Poffset1 to the shifted sensor output (for example, SSup). This correction is performed, for example, so that the middle point of the output waveform (position where the median of the output level is taken) falls within a predetermined allowable range from the median value VDD / 2 of the output voltage range (GND to VDD) of the sensor. To be executed.

  FIG. 16C shows an example of the sensor output waveform SSrignt shifted to the right side from the desired sensor output SSideal and the sensor output SSleft shifted to the left side. In such a case, a waveform close to the desired sensor output SSideal can be corrected by adding a left-right offset Poffset2 to the shifted sensor output (for example, SSright). This correction is performed according to a predetermined tolerance from the phase of the middle point of the output waveform (the position where the median value of the output level is taken) from the phase where the sensor output voltage range (GND to VDD) takes the median value VDD / 2. It is executed to fit within the range. Whether the sensor output is offset in the left-right direction is determined by stopping the motor rotor at a predetermined specified position (a position that should be the middle point of the output waveform). It can be determined by examining whether or not the median value is VDD / 2.

  As described above, both the vertical offset Poffset1 and the horizontal offset Poffset2 can be corrected as the offset. However, it is often sufficient in practice to correct only one of these two offsets. Therefore, in the procedure to be described later, a case will be described in which only the vertical offset Poffset1 is corrected among the two types of offsets.

  FIG. 17 is an explanatory diagram showing the contents of gain correction of the sensor output. FIG. 17A shows a desirable output waveform SSideal of the sensor output, which is the same as FIG. FIG. 17B shows an example of a sensor output waveform SSsmall having a smaller peak than the desired sensor output SSideal. In this case, the sensor output SSsmall can be corrected to a waveform close to the desired sensor output SSideal by multiplying the sensor output SSsmall by a gain Pgain larger than 1. More specifically, this gain correction is executed so that the peak value of the sensor output after correction falls within a predetermined allowable range. FIG. 17C shows an example of the sensor output waveform SSlarge having a peak larger than the desired sensor output SSideal. In the output waveform SSlarge, the portion exceeding the maximum value VDD (power supply voltage) of the voltage range is stopped at VDD, so that a waveform having a flat peak portion is observed as indicated by a one-dot chain line. In this case, the sensor output SSlarge can be corrected to a waveform close to the desired sensor output SSideal by multiplying the sensor output SSlarge by a gain Pgain smaller than 1.

  FIG. 18 is a flowchart showing the calibration procedure of the sensor output. In step S100, the drive control circuit 200 for calibration is mounted on the motor main body 100 (FIG. 7A). In step S200, the offset correction described in FIG. 16B is performed, and in step S300, the gain correction described in FIGS. 17B and 17C is performed. In step S400, the drive control circuit is replaced with a practical circuit 300 (FIG. 7B).

  FIG. 19 is a flowchart showing a detailed procedure of offset correction in step S200. In the following, offset correction of the A phase sensor will be described, but the same correction is performed for the B phase sensor. When offset correction is performed for one magnetic sensor, the CPU 220 first designates the ID of the magnetic sensor to be corrected, and starts correction processing for the designated magnetic sensor.

  In step S210, the rotor unit 30 (FIG. 1) is rotated to stop the magnetic sensor 16A at the boundary position between the S pole and the N pole of the magnet. This operation can be performed manually by opening the lid of the motor body, for example. In step S220, the initial value of the offset Poffset is transmitted from the drive control circuit 200 to the magnetic sensor 16A, and is stored in the offset storage unit 440 (FIG. 9) in the magnetic sensor 16A. An arbitrary value can be used as the initial value of the offset Poffset. However, it is preferable to set the initial value to a positive value other than 0 so that the offset Poffset can be increased or decreased by offset correction.

  In step S230, the voltage Ebc of the output signal SSA output from the magnetic sensor 16A is measured. In step S240, it is determined whether or not the measured voltage Ebc is equal to or greater than the minimum value E1min (see FIG. 16B) of the allowable range. When the voltage Ebc is smaller than the minimum value E1min of the allowable range, the voltage Ebc is out of the allowable range. Therefore, the process proceeds to step S250, and one offset value Poffset is added. In step S280, the offset value is added to the magnetic sensor 16A. Write Poffset. On the other hand, if the voltage Ebc is not less than the minimum allowable value E1min in step S240, it is further determined in step S260 whether or not the voltage Ebc is not more than the maximum allowable value E1max. When the voltage Ebc is larger than the maximum value E1max of the allowable range, the voltage Ebc is outside the allowable range. Therefore, the process proceeds to step S270, one offset value Poffset is subtracted, and the offset value is added to the magnetic sensor 16A in step S280. Write Poffset. On the other hand, if the voltage Ebc is equal to or smaller than the maximum value E1max of the allowable range in step S260, the voltage Ebc is within the allowable range, and the process of FIG.

  FIG. 20 is a flowchart showing a detailed procedure of gain correction in step S300. As for the gain correction, only the correction of the A phase sensor will be described. When gain correction is performed for one magnetic sensor, the CPU 220 first specifies the ID of the magnetic sensor to be corrected, and starts correction processing for the specified magnetic sensor.

  In step S310, the rotor unit 30 (FIG. 1) is rotated to stop the magnetic sensor 16A at a position facing the S pole or N pole of the magnet. This position is a position where the magnetic flux density of the magnetic sensor 16A is maximized. This operation can be performed manually, for example, by opening the lid of the motor body. In step S320, the initial value of the gain Pgain is transmitted from the drive control circuit 200 to the magnetic sensor 16A and stored in the gain storage unit 450 (FIG. 9) in the magnetic sensor 16A. Although an arbitrary value can be used as the initial value of the gain Pgain, it is preferably set to a positive value other than 0.

  In step S330, the voltage Ebm of the output signal SSA of the magnetic sensor 16A is measured. In step S340, it is determined whether or not the measured voltage Ebm is greater than or equal to the minimum value E2min (see FIG. 17B) of the allowable range. When the voltage Ebm is smaller than the minimum value E2min of the allowable range, the voltage Ebm is out of the allowable range. Therefore, the process proceeds to step S350, one gain value Pgain is added, and the gain value is added to the magnetic sensor 16A in step S380. Write Pgain. On the other hand, if the voltage Ebm is not less than the minimum value E2min of the allowable range in step S340, it is further determined in step S360 whether or not the voltage Ebm is not more than the maximum value E2max of the allowable range. When the voltage Ebm is larger than the maximum value E2max of the allowable range, the voltage Ebm is outside the allowable range. Therefore, the process proceeds to step S370, one gain value Pgain is subtracted, and the gain value is added to the magnetic sensor 16A in step S380. Write Pgain. On the other hand, if the voltage Ebm is equal to or smaller than the maximum value E2max of the allowable range in step S360, the voltage Ebm is within the allowable range, and the processing in FIG.

  The maximum value E2max of the allowable range at the time of gain correction is preferably a value slightly smaller than the maximum value that can be taken by the sensor output (that is, the power supply voltage VDD). This is because the sensor output voltage cannot be larger than the power supply voltage VDD, and if the maximum value E2max of the allowable range is set to the power supply voltage VDD, the peak of the sensor output SSA before correction is shown in FIG. This is because it may not be possible to determine whether or not the image is crushed as indicated by the alternate long and short dash line.

  As described above, in the electric motor of this embodiment, it is possible to perform output waveform offset correction and gain correction for each of the magnetic sensors 16A and 26B. In addition, the drive control circuit 300 generates a drive signal by using a continuous change in the analog output of these sensors. Therefore, by correcting the outputs of the magnetic sensors 16A and 26B to a predetermined waveform shape, it is possible to realize a motor with high efficiency and less vibration and noise.

D. Other embodiments of the drive control circuit:
FIG. 21 is a block diagram showing another embodiment of the drive control circuit for calibration. The drive control circuit 200a is obtained by omitting the power supply circuit 210, the PWM control unit 240, and the driver circuit 250 from the drive control circuit 200 shown in FIG. The power to the motor main body 100a is directly supplied to the motor main body 100a via the connection unit 90. The PWM controller 240 and the driver circuit 250 are provided inside the motor main body 100a. Even with such a configuration, it is possible to operate the motor with high efficiency by correcting the output waveform of the sensor in the same manner as the motor shown in FIG.

  FIG. 22 is a block diagram showing a configuration of a magnetic sensor and a drive signal generation circuit in still another embodiment of the present invention. In this embodiment, the magnetic sensors 16A and 26B include only the magnetic sensor element, and the other circuit elements 420 to 480 in the magnetic sensor shown in FIG. 9 are not included in the magnetic sensor. The drive signal generation circuit 600 includes amplifiers 610 and 620, AD conversion units 612 and 622, offset correction circuits 614 and 624, gain correction circuits 616 and 626, a PWM control unit 240, a correction value storage unit 660, And a communication unit 670. The offset correction circuits 614 and 624 are the same as the offset correction circuit 420 shown in FIG. 9, and the gain correction circuits 616 and 626 are the same as the gain correction circuit 430 shown in FIG. The correction value storage unit 660 stores an offset correction value and a gain correction value related to both the A-phase sensor 16A and the B-phase sensor 26B in association with the respective ID codes. The PWM control unit 240 is the same as that shown in FIG. The communication unit 670 is connected to the CPU 220 via the I / O interface 230. During calibration, the outputs of the sensors 16A and 26B are amplified by the amplifiers 610 and 620, converted into digital signals by the AD converter 232, and then supplied to the CPU 220 via the I / O interface 230.

  In the circuit configuration of FIG. 22, for example, the drive signal generation circuit 600 and the driver circuit 250 are installed in the motor body, and a circuit including the CPU 220, the I / O interface 230, and the AD conversion unit 232 is connected to the motor body connection unit 90. (Fig. 7A) can be connected. Even if such a circuit configuration is adopted, it is possible to correct the output waveform of the sensor and operate the motor with high efficiency as in the above embodiment.

  FIG. 23 is a block diagram showing another embodiment of the drive signal generation circuit. The drive signal generation circuit 600a is obtained by replacing the PWM control unit 240 of the drive signal generation circuit 600 shown in FIG. 22 with a preamplifier unit 630 and an amplifier unit 640, and other configurations are the same as those in FIG. . The preamplifier unit 630 and the amplifier unit 640 generate drive signals by amplifying the corrected analog sensor output as it is. Thus, even when the sensor output is amplified using an analog circuit without using PWM control, it is possible to operate the motor with high efficiency by correcting the sensor waveform described above.

E. Other implementation steps for sensor output correction:
FIG. 24 is a flowchart showing another procedure for offset correction. In step S1200, the CPU 220 rotates the rotor unit 30. In the procedure of FIG. 24, the CPU 220 performs offset correction after step S1210 while the rotor unit 30 continues to rotate. In step S1210, the initial value of the offset Poffset is transmitted from the drive control circuit 200 to the magnetic sensor 16A and stored in the offset storage unit 440 (FIG. 9) in the magnetic sensor 16A. This process is the same as step S220 in FIG.

  In step S1220, the sensor output maximum voltage Ebcmax and minimum voltage Ebcmin are acquired. These voltages Ebcmax and Ebcmin correspond to the upper peak value and the lower peak value of the sensor output SSup (or SSdown) shown in FIG. In step S1230, an average value Ebctyp of the maximum voltage Ebcmax and the minimum voltage Ebcmin is calculated. This average value Ebctyp is a voltage value corresponding to the middle point of the output waveform of the sensor.

  Steps S1240 to S1280 are substantially the same as steps S240 to S280 in FIG. 19, and correspond to the voltage value Ebc in FIG. 19 replaced with the above-described average value Ebctyp. That is, in steps S1240 to S1280, the offset value Poffset is adjusted so that the average value Ebctyp falls within the allowable range shown in FIG.

  As can be understood from this example, the offset correction can also be performed using the peak voltage of the sensor voltage. Note that the procedure of FIG. 24 has an advantage that the correction work is easy because it is not necessary to position the rotor portion at a position corresponding to the cautionary point of the sensor output waveform unlike the procedure of FIG.

  FIG. 25 is a flowchart showing another procedure for gain correction. In step S1300, CPU 220 rotates rotor unit 30. In the procedure of FIG. 25, the CPU 220 performs gain correction after step S1310 while the rotor unit 30 continues to rotate. In step S1310, the initial value of the gain Pgain is transmitted from the drive control circuit 200 to the magnetic sensor 16A and stored in the gain storage unit 450 (FIG. 9) in the magnetic sensor 16A. This process is the same as step S320 in FIG.

  In step S1320, the sensor output maximum voltage Ebmmax is acquired a predetermined number of times. The maximum voltage Ebmmax corresponds to the upper peak value of the sensor output SSsmall shown in FIG. 17B (or SSlarge in FIG. 17C), for example. Note that the lower peak value may be acquired a predetermined number of times instead of the upper peak value. Note that the number of upper peak values that appear during one rotation of the rotor portion is equal to ½ of the number of poles P of the motor. In the 6-pole motor shown in FIG. 1, the upper peak value appears three times per rotation. In step S1320, it is preferable to sample (P × N) / 2 maximum voltages Ebmmax. Here, N is a predetermined integer of 1 or more, and preferably 2 or more. In step S1230, an average value Ebmave of (P × N) / 2 maximum voltages Ebmmax is calculated.

  Steps S1340 to S1380 are substantially the same as steps S340 to S380 in FIG. 20, and correspond to the voltage value Ebm in FIG. 20 replaced with the above-described average value Ebmave. That is, in steps S1340 to S1380, the gain value Pgain is adjusted so that the average value Ecmave falls within the allowable range shown in FIG.

  The procedure of FIG. 25 has an advantage that the correction work is easy because it is not necessary to position the rotor portion at a position corresponding to the cautionary point of the sensor output waveform unlike the procedure of FIG. In addition, since gain correction is performed using an average value of a plurality of peak voltages, the most preferable gain can be set in consideration of the whole of the plurality of magnets.

  FIG. 26 is a flowchart showing still another procedure for performing gain correction. The procedure in FIG. 26 is obtained by replacing steps S1330, S1340, and S1360 in FIG. 25 with steps S1335, S1345, and S1365, and the other procedures are the same as those in FIG.

  In step S1335, the maximum value Ebmpk is selected from the (P × N) / 2 maximum voltages Ebmmax. In steps S1345 and S1365, gain correction is performed using the maximum value Ebmpk. Even in this way, it is possible to obtain an appropriate gain correction value Pgain.

  Note that the threshold values E2min and E2max used in steps S1345 and S1365 in FIG. 26 are different from the threshold values E2min and E2max used in steps S1340 and S1360 in FIG. Also good.

F. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

F1. Modification 1:
In the above embodiment, both the gain correction and the offset correction are executed as the correction of the sensor output waveform. However, only one of them may be corrected. Further, the sensor output waveform may be corrected to a desired waveform shape using other types of correction. In the above-described embodiment, the waveform of the sensor output and the back electromotive force is a sine wave. However, the present invention can also be applied when these waveforms are slightly different from the sine wave.

F2. Modification 2:
In the above embodiment, an analog magnetic sensor is used, but a digital magnetic sensor having a multi-valued analog output may be used instead of the analog magnetic sensor. An analog magnetic sensor and a digital magnetic sensor having a multi-value output are common in that they have an output signal indicating an analog change. In this specification, “an output signal indicating an analog change” includes both a digital output signal having multiple levels of three or more and an analog output signal, not an on / off binary output. Used in a broad sense.

F3. Modification 3:
In the above-described embodiment, the drive control circuit at the time of calibration and the drive control circuit at the time of practical use are respectively used. Instead, the drive control circuit at the time of practical use is used as it is at the time of calibration, and the circuit for calibration is used. May be connected to the connection unit 90. As the calibration circuit, any circuit having a function of registering a correction value of the output waveform of the sensor in the motor can be used.

F4. Modification 4:
As the PWM circuit, various circuit configurations other than the circuit shown in FIG. 10 can be adopted. For example, a circuit that performs PWM control by comparing the sensor output with a reference triangular wave may be used. In this case, during PWM control, the gain of the sensor output is adjusted according to the desired applied voltage, but this gain adjustment is different from the gain correction described with reference to FIG. In other words, the gain correction described with reference to FIG. 17 is correction for shaping the sensor output into a desired waveform regardless of the desired applied voltage level.

F5. Modification 5:
In the above embodiment, a 6-pole 2-phase brushless DC motor has been described. However, the present invention can be applied to various other electric motors. For example, any integer can be adopted as the number of poles and the number of phases.

It is sectional drawing which shows the structure of the motor main body of the electric motor in an Example. It is explanatory drawing which shows the positional relationship of the coil row | line | column and magnet row | line in an Example. It is explanatory drawing which shows the output waveform of a magnetic sensor. It is a schematic diagram which shows the relationship between the applied voltage of a coil, and a counter electromotive force. It is explanatory drawing which shows the connection method of a coil. It is explanatory drawing which shows the operation | movement principle of the electric motor in an Example. It is a block diagram which shows the structure of the drive control circuit of the motor of an Example. It is a figure which shows the internal structure of a driver circuit. It is a block diagram which shows the internal structure of a magnetic sensor. It is explanatory drawing which shows the internal structure and operation | movement of PWM control part 240. FIG. It is explanatory drawing which shows the correspondence of a sensor output waveform and a drive signal waveform. It is a block diagram which shows the internal structure of a PWM part. It is a timing chart which shows operation | movement of the PWM part at the time of motor forward rotation. It is a timing chart which shows operation | movement of the PWM part at the time of motor reverse rotation. It is explanatory drawing which shows the internal structure and operation | movement of an excitation area setting part. It is explanatory drawing which shows the content of the offset correction of a sensor output. It is explanatory drawing which shows the content of the gain correction of a sensor output. It is a flowchart which shows the calibration procedure of a sensor output. It is a flowchart which shows the detailed procedure of offset correction. It is a flowchart which shows the detailed procedure of gain correction. It is a block diagram which shows the other Example of the drive control circuit for a calibration. It is a block diagram which shows the structure of the magnetic sensor in another Example of this invention, and a drive signal generation circuit. It is a block diagram which shows the other Example of a drive signal generation circuit. It is a flowchart which shows the other implementation procedure of offset correction. It is a flowchart which shows the other implementation procedure of gain correction. It is a flowchart which shows the other execution procedure of gain correction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Stator part 12A ... Support member 14A ... A phase coil row | line | column 16A ... A phase sensor (analog magnetic sensor)
22B ... Support member 24B ... B phase coil array 26B ... B phase sensor (analog magnetic sensor)
DESCRIPTION OF SYMBOLS 30 ... Rotor part 32M ... Support member 34M ... Magnet row 90 ... Connection part 100 ... Motor body 112 ... Rotating shaft 200 ... Drive control circuit (during calibration)
210 ... Power supply circuit 220 ... CPU
230 ... I / O interface 232 ... AD converter 240 ... PWM controller 250 ... Driver circuit 252 ... A phase driver circuit 254 ... B phase driver circuit 260 ... Communication unit 300 ... Drive control circuit (when practical)
410: Magnetic sensor element 420 ... Offset correction circuit 430 ... Gain correction circuit 440 ... Offset storage unit 450 ... Gain storage unit 460 ... Amplifier 470 ... ID code recording unit 480 ... Communication unit 510 ... Basic clock generation circuit 520 ... Frequency divider 530 ... PWM unit 531,532 ... Counter 533,534 ... EXOR circuit 535,536 ... Drive waveform forming unit 540 ... Register 550,552 ... Multiplier 560,562 ... Encoding unit 570,572 ... AD converter 580 ... Voltage command value Register 590 ... Excitation section setting unit 592 ... Electronic variable resistor 594, 596 ... Voltage comparator 598 ... OR circuit 600 ... Drive signal generation circuit 610, 620 ... Amplifier 612, 622 ... AD converter 614, 624 ... Offset correction circuit 616 , 626... Gain correction circuit 630 ... Preamplifier unit 640 ... Amplifier unit 660 ... Storage unit 670 ... Communication unit

Claims (3)

An electric motor,
A stator including a coil array having a plurality of electromagnetic coils;
A rotor comprising a magnet array having a plurality of permanent magnets;
A plurality of magnetic sensors that output an output signal indicating an analog change according to the relative positions of the magnet array and the coil array;
A drive control circuit that generates an applied voltage to the coil array using an analog change in output signals of the plurality of magnetic sensors;
An output waveform correction unit that respectively performs gain correction and offset correction of the output signals of the plurality of magnetic sensors so that the output signals of the plurality of magnetic sensors at the time of operation of the electric motor each have a predetermined waveform shape;
A correction value setting unit for setting a correction value for waveform correction in the output waveform correction unit;
With
The output waveform correction unit has a memory for storing a gain correction value and an offset correction value ,
An identification ID code is assigned to each of the plurality of magnetic sensors,
The correction value setting unit measures a peak voltage of an output signal of each magnetic sensor a plurality of times while the rotor continues to rotate, and calculates an average value of the peak voltage in the plurality of measurements as a gain correction value of the magnetic sensor. And the gain correction value of each magnetic sensor is transmitted to the output waveform correction unit together with the ID code of each magnetic sensor and stored in the memory . An electric motor,
A stator including a coil array having a plurality of electromagnetic coils;
A rotor comprising a magnet array having a plurality of permanent magnets;
A plurality of magnetic sensors that output an output signal indicating an analog change according to the relative positions of the magnet array and the coil array;
A drive control circuit that generates an applied voltage to the coil array using an analog change in output signals of the plurality of magnetic sensors;
An output waveform correction unit that respectively performs gain correction and offset correction of the output signals of the plurality of magnetic sensors so that the output signals of the plurality of magnetic sensors at the time of operation of the electric motor each have a predetermined waveform shape;
A correction value setting unit for setting a correction value for waveform correction in the output waveform correction unit;
With
The output waveform correction unit has a memory for storing a gain correction value and an offset correction value ,
An identification ID code is assigned to each of the plurality of magnetic sensors,
The correction value setting unit measures the peak voltage of the output signal of each magnetic sensor a plurality of times while the rotor continues to rotate, and sets the maximum value of the peak voltage in the plurality of measurements to the gain correction value of the magnetic sensor. And the gain correction value of each magnetic sensor is transmitted to the output waveform correction unit together with the ID code of each magnetic sensor and stored in the memory . The electric motor according to claim 1 or 2,
The correction value setting unit measures a maximum voltage and a minimum voltage of an output signal of each magnetic sensor while the rotor continues to rotate, and determines an average value of the maximum voltage and the minimum voltage as an offset correction value of the magnetic sensor. The offset correction value is transmitted to the output waveform correction unit together with the gain correction value and the ID code of each magnetic sensor and stored in the memory .

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