Motor drive control device, motor unit, and motor drive control method

Abstract

The present application relates to a motor drive control device, a motor unit, and a motor drive control method. The motor drive control device (10) has a control section (11) that generates a control signal (Sd) so as to alternately repeat one-phase excitation in which one-phase coils (21) of two-phase coils (21A, 21B) in a two-phase stepping motor (20) are excited and two-phase excitation in which two-phase coils (21) are excited. A drive section (12) drives the two-phase coils based on the control signal. A conduction angle (θ) that indicates the magnitude of a conduction angle in which one-phase coils are continuously excited in one direction can be set in the control section. The control section determines a period (T1n) in which one-phase excitation is performed based on a counter electromotive voltage generated by coils that are not excited in one-phase excitation, and determines a period (T2n) in which two-phase excitation is performed based on the elapsed time per unit angle when the two-phase stepping motor is being excited and the conduction angle.

Description

Technical Field

[0001] This invention relates to a motor drive control device, a motor unit, and a motor drive control method, for example, to a motor drive control device for driving a stepper motor. Background Technology

[0002] As a stepper motor, a two-phase stepper motor with two phases is known.

[0003] As driving methods for two-phase stepper motors, one-phase excitation, two-phase excitation, and 1-2 phase excitation are known.

[0004] A single-phase excitation mode is a mode in which the energized phase is switched for each phase. In a single-phase excitation mode, the energizing angle, which represents the magnitude of the energizing angle of a coil continuously energized in one direction for a single phase, is 90 degrees. The two-phase stepper motor commutates every 90 degrees.

[0005] Two-phase excitation mode involves switching the energized phase every two phases. In two-phase excitation mode, the energizing angle is 180 degrees, and the two-phase stepper motor commutates every 90 degrees.

[0006] The 1-2 phase excitation mode is a method of switching the excitation phase by alternating between one-phase excitation and two-phase excitation. In the 1-2 phase excitation mode, the energizing angle is generally 135 degrees, and the two-phase stepper motors commutate every 45 degrees.

[0007] For example, Patent Document 1 discloses a motor drive control technology as follows: In order to suppress the uneven speed of a stepper motor when driving a two-phase stepper motor in a 1-2 phase excitation mode, a period is set in which the same phase as the next two-phase excitation period is used for two-phase excitation during the one-phase excitation period.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2010-93914 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] As a method for controlling the drive of a two-phase stepper motor in a specified application, the inventors have studied a control method that allows the speed of the two-phase stepper motor to vary according to the load by using a 1-2 phase excitation mode where the generated torque is greater than that of a single phase excitation. Specifically, this control method is a closed-loop control method that detects the point where the back electromotive force voltage of the non-excited coil becomes zero during the single-phase excitation period (zero-crossing point), thereby determining the rotor position of the two-phase stepper motor, and determining the commutation timing based on the determined rotor position, thereby generating an appropriate torque for the load.

[0013] In the control method studied by the inventors, it is necessary to detect the zero-crossing point of the back electromotive force voltage generated in the unexcited coil. The period during which the zero-crossing point of the back electromotive force voltage can be detected is only the duration of one phase of excitation. However, in a typical 1-2 phase excitation mode with a 135-degree energizing angle, the two-phase stepper motors commutate every 45 degrees. Therefore, the duration of one phase excitation is shorter than in a single-phase excitation mode, which may not ensure sufficient time for detecting the zero-crossing point of the back electromotive force voltage. This problem will be explained in detail below using the accompanying drawings.

[0014] Figure 8 This diagram illustrates the power-on switching control of a conventional two-phase stepper motor based on a 1-2 phase excitation method with a fixed power-on angle of 135°.

[0015] exist Figure 8 In the figure, reference numeral 801 indicates the voltage of the coil of phase A, and reference numeral 802 indicates the back electromotive force voltage of the coil of phase A.

[0016] like Figure 8 As shown, in the 1-2 phase excitation mode, alternating between one-phase and two-phase excitation is used to switch the energizing state of the two-phase stepper motor. For example, in... Figure 8 In the process, during the period from 180° to 225°, a negative drive voltage (-V) is applied to the coil of phase A to energize it negatively, and a negative drive voltage (-V) is also applied to the coil of phase B to energize it negatively. In the next period from 225° to 270°, a negative drive voltage (-V) continues to be applied to the coil of phase B to energize it negatively, while the drive voltage of the coil of phase A is set to "0", and it is not energized. Then, during the period from 270° to 315°, a positive drive voltage is applied to the coil of phase A to energize it positively, and a negative drive voltage continues to be applied to the coil of phase B to energize it negatively.

[0017] In this way, in the conventional 1-2 phase excitation mode, the current angle, which represents the magnitude of the current angle of continuous energization of a coil in one phase in one direction, is 135°, and the one-phase excitation and two-phase excitation are switched alternately every 45°.

[0018] Therefore, in a 1-2 phase excitation mode, the back electromotive force voltage of the A-phase or B-phase coil cannot be detected unless a driving voltage is applied to the coil. For example, Figure 8 As shown, during the period from electrical angle 180° to 225°, a negative drive voltage is applied to the coil of phase A, therefore the back EMF voltage of phase A cannot be detected. On the other hand, during the period from electrical angle 225° to 270°, no drive voltage is applied to the coil of phase A, therefore the back EMF voltage of phase A can be detected. Thus, in the 1-2 phase excitation mode, the zero-crossing point of the back EMF voltage can be detected during the period of excitation of only one phase.

[0019] However, in the drive control method studied by the inventors of this application, which uses a conventional 1-2 phase excitation mode with a fixed energizing angle of 135°, it may be impossible to detect the zero-crossing point of the back electromotive force voltage during the excitation period of one phase.

[0020] For example, such as Figure 8 As shown, during the period of single-phase excitation from an electrical angle of 225° to 270°, immediately after switching from two-phase excitation to single-phase excitation, a spike-like voltage is generated in the coil of the non-excited phase A. The time until this spike-like voltage stabilizes depends on the coil inductance, the magnitude of the load, etc.

[0021] Therefore, based on conditions such as the coil inductance and the load size, such as Figure 8 As shown, after switching from two-phase excitation to one-phase excitation, it takes time for the back electromotive force voltage generated in the non-excited coil to stabilize. It may be impossible to detect the zero-crossing point of the back electromotive force voltage during the one-phase excitation period, and stable energization switching may not be possible.

[0022] The present invention was made in view of the above-mentioned problems, and its purpose is to realize stable power-on switching of a two-phase stepper motor based on a 1-2 phase excitation mode.

[0023] Technical solution

[0024] A representative embodiment of the motor drive control device of the present invention is characterized by comprising: a control unit that generates a control signal for controlling the drive of a two-phase stepper motor, so as to alternately and repeatedly perform one-phase excitation of a coil energizing one phase of the two-phase coils in the two-phase stepper motor and two-phase excitation of a coil energizing both phases of the two-phase coils; and a drive unit that drives the two-phase coils based on the control signal, wherein the control unit can set an energizing angle, the energizing angle representing the magnitude of an angle at which the coil of one phase is continuously energized in one direction, the control unit determining the period of one-phase excitation based on the back electromotive force voltage generated in the coil during the one-phase excitation and in the non-excited phase, and determining the period of two-phase excitation based on the elapsed time per unit angle when the two-phase stepper motor is being energized and the energizing angle.

[0025] Invention Effects

[0026] According to the motor drive control device of the present invention, stable power-on switching of a two-phase stepper motor based on a 1-2 phase excitation mode can be achieved. Attached Figure Description

[0027] Figure 1 This is a block diagram illustrating the configuration of a motor unit according to an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram illustrating the configuration of a motor according to an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram illustrating the power-on switching control of a two-phase stepper motor based on a 1-2 phase excitation mode, used to explain an embodiment of the present invention.

[0030] Figure 4 This diagram illustrates the power-on switching control of a two-phase stepper motor implemented by the motor drive control device according to an embodiment of the present invention.

[0031] Figure 5 This is a diagram illustrating the method for determining the target energizing time of two-phase excitation based on the first method in this embodiment.

[0032] Figure 6 This is a diagram showing the functional block configuration of the control unit in a motor drive control device according to an embodiment of the present invention.

[0033] Figure 7 This is a flowchart illustrating a specific example of the process of power-on switching control of a two-phase stepper motor implemented by the motor drive control device of this embodiment.

[0034] Figure 8This diagram illustrates the power-on switching control of a conventional two-phase stepper motor based on a 1-2 phase excitation method with a fixed power-on angle of 135°. Detailed Implementation

[0035] 1. Overview of the implementation method

[0036] First, a summary description of representative embodiments of the invention disclosed in this application will be given. It should be noted that, in the following description, as an example, reference numerals in the accompanying drawings corresponding to the constituent elements of the invention will be enclosed in parentheses.

[0037] [1] A motor drive control device (10) according to a representative embodiment of the present invention is characterized by having: a control unit (11) that generates a control signal (Sd) for controlling the drive of a two-phase stepper motor (20) so as to alternately and repeatedly perform one-phase excitation of the coil energizing one phase of the two-phase coils (21A, 21B) in the two-phase stepper motor and two-phase excitation of the coils energizing both phases of the two-phase coils; and a drive unit (12) that drives the two-phase coils based on the control signal, and can set an energizing angle (θ) in the control unit, the energizing angle representing the magnitude of the energizing angle of the coil continuously energized in one direction in one phase, the control unit determining the period (T1n) of the one-phase excitation based on the back electromotive force voltage generated in the coils that are not energized during the one-phase excitation, and determining the period (T2n) of the two-phase excitation based on the elapsed time of each unit angle when the two-phase stepper motor is being energized and the energizing angle.

[0038] [2] In the motor drive control device described in [1] above, the control unit generates the control signal based on the detection result of the zero-crossing point of the back electromotive force voltage generated by the coil in the non-excited phase during the excitation of the one phase, so as to switch the excitation state of the two-phase stepper motor from the one-phase excitation to the two-phase excitation. The control unit determines the target energizing time (T2n) based on the elapsed time of each unit angle and the energizing angle, and generates the control signal after the two-phase excitation starts and after the target energizing time has elapsed, so as to switch the excitation state of the two-phase stepper motor from the two-phase excitation to the one-phase excitation.

[0039] [3] In the motor drive control device described in [2] above, the control unit measures the period (T1n) of the excitation of one phase, and the elapsed time per unit angle is the value obtained by dividing the measured value of the period of the excitation of one phase by the size of the electrical angle corresponding to the period of the excitation of that phase.

[0040] [4] In the motor drive control device described in [3] above, when the measured value of the period of excitation of one phase is set as T1n, the energizing angle is set as θ, and the target energizing time is set as T2n, the target energizing time is calculated based on the formula (1) described later.

[0041] [5] In the motor drive control device described in [3] or [4] above, the control unit measures the period of the one-phase excitation that occurs immediately before the two-phase excitation and sets the period as the measured value of the one-phase excitation period.

[0042] [6] In the motor drive control device described in [3] or [4] above, the control unit measures a plurality of periods of one-phase excitation before the two-phase excitation and sets the average value of the plurality of measured periods as the measured value of the period of one-phase excitation.

[0043] [7] In the motor drive control device described in [2] above, the control unit measures the time between the zero-crossing points of the back electromotive force voltage, and the elapsed time per unit angle is the value obtained by dividing the measured value of the time between the zero-crossing points by the size of the electric angle between the zero-crossing points.

[0044] [8] In the motor drive control device described in [7] above, when the measured value of the time between the zero-crossing points of the back electromotive force voltage is set as Tz, the size of the measured electric angle between the zero-crossing points is set as α, the energizing angle is set as θ, and the target energizing time is set as T2n, the control unit calculates the target energizing time based on the formula (3) described later.

[0045] [9] may be, in any of the motor drive control devices described in [1] to [8] above, the energizing angle is a value of 90° or more and 135° or less.

[0046]

[10] The motor unit (1) of a representative embodiment of the present invention is characterized by comprising: a motor drive control device (10) as described in any one of [1] to [9] above; and the two-phase stepper motor (20).

[0047]

[11] A representative embodiment of the present invention is a motor drive control method for controlling the drive of a two-phase stepper motor (20) by means of a motor drive control device (10). The method is characterized by comprising: a first step (S2, S4-S7, S9-S12), wherein the motor drive control device generates a control signal for controlling the drive of the two-phase stepper motor, so as to alternately and repeatedly perform one-phase excitation of a coil energizing one phase of the two-phase coils (21A, 21B) in the two-phase stepper motor and two-phase excitation of a coil energizing both phases of the two-phase coils; and a second step (S3, S8), wherein the motor drive control device drives the two-phase stepper motor (20) based on the control signal. The two-phase coils are energized by a motor drive control device with an energizing angle (θ), the energizing angle representing the magnitude of the unidirectional continuous energizing angle of one phase coil. The first step includes: a third step (S4-S7), determining the period for energizing the one phase based on the back electromotive force voltage generated in the coil during energization and in non-energization of the one phase; and a fourth step (S9-S12), determining the period for energizing the two phases based on the elapsed time of each unit angle when the two-phase stepper motor is being energized and the energizing angle.

[0048] 2. Specific examples of implementation methods

[0049] Hereinafter, specific examples of embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that in the following description, common components in various embodiments are labeled with the same reference numerals and repeated descriptions are omitted.

[0050] Figure 1 This is a block diagram illustrating the configuration of a motor unit according to an embodiment of the present invention.

[0051] like Figure 1 As shown, the motor unit 1 includes a two-phase stepper motor 20 and a motor drive control device 10 for driving the two-phase stepper motor 20. The motor unit 1 can be applied, for example, to various devices that use motors such as actuators that can be used in HVAC (Heating, Ventilation and Air-Conditioning) units used as air conditioning units in vehicles as a power source.

[0052] Figure 2 This is a schematic diagram illustrating the configuration of a two-phase stepper motor 20 according to an embodiment of the present invention.

[0053] The two-phase stepper motor 20 is, for example, a stepper motor with two-phase coils. Figure 2 As shown, the two-phase stepper motor 20 has an A-phase coil 21A, a B-phase coil 21B, a rotor 22, and a two-phase stator yoke (not shown).

[0054] Coils 21A and 21B are coils that excite the stator yoke (not shown). Coils 21A and 21B are connected to the drive unit 12, which will be described later. Currents (coil currents) of different phases flow in coils 21A and 21B.

[0055] It should be noted that in this embodiment, without distinguishing between coils 21A and 21B, they are sometimes simply referred to as "coil 21".

[0056] Rotor 22 is a permanent magnet with multi-pole magnetization, wherein the S pole 22S and N pole 22N alternately reverse in the circumferential direction. It should be noted that, in Figure 2 The example shown is the case where rotor 22 has two poles.

[0057] The stator yoke is positioned around the rotor 22 close to its outer periphery. The rotor 22 rotates by periodically switching the phase of the coil current flowing through each of the coils 21A and 21B. An output shaft (not shown) is connected to the rotor 22 and is driven by the rotational force of the rotor 22.

[0058] The motor drive control device 10 is a device for driving a two-phase stepper motor 20. The motor drive control device 10 controls the energization state of the coils 21A and 21B of each phase of the two-phase stepper motor 20 based on drive commands, for example, from a host device (not shown), thereby controlling the rotation and stopping of the two-phase stepper motor 20.

[0059] like Figure 1 As shown, the motor drive control device 10 has a control unit 11 and a drive unit 12.

[0060] The drive unit 12 is a functional unit that energizes the coils 21A and 21B of the two-phase stepper motor 20 to drive the two-phase stepper motor 20. The drive unit 12 includes a motor drive unit 121.

[0061] The motor drive unit 121 supplies drive power to the two-phase stepper motor 20 based on the control signal Sd generated by the control unit 11. For example... Figure 2 As shown, the drive unit 12 is connected to the terminal AP on the positive side of coil 21A, the terminal AN on the negative side of coil 21A, the terminal BP on the positive side of coil 21B, and the terminal BN on the negative side of coil 21B, respectively. By applying voltage to each terminal AP, AN, BP, and BN, coils 21A and 21B are energized.

[0062] The motor drive unit 121 is configured, for example, as an H-bridge circuit including four switching elements (e.g., transistors). The motor drive unit 121 switches the energization of coils 21A and 21B by selectively turning on / off each of the switching elements constituting the H-bridge circuit.

[0063] like Figure 2 As shown, when the current +Ia flows through the coil 21A of phase A, the motor drive unit 121 applies a voltage of "+Va" to the terminal AP relative to the terminal AN of coil 21A. On the other hand, when the current -Ia flows through the coil 21A of phase A, the motor drive unit 121 applies a voltage of "-Va" to the terminal AP relative to the terminal AN of coil 21A. Similarly, for the coil 21B of phase B, when the current +Ib flows through the coil 21B of phase B, the motor drive unit 121 applies a voltage of "+Vb" to the terminal BP relative to the terminal BN of coil 21B, and when the current -Ib flows through the coil 21B of phase B, the motor drive unit 121 applies a voltage of "-Vb" to the terminal BP relative to the terminal BN of coil 21B.

[0064] Based on the control signal Sd from the control unit 11, the motor drive unit 121 switches the voltage applied between the terminals of each coil 21A and 21B as described above, thereby switching the energization state of each coil 21A and 21B.

[0065] The control unit 11 is a functional unit that performs overall control of the motor drive control device 10. The control unit 11 is, for example, a program processing device (e.g., a microcontroller) that interconnects a processor such as a CPU (central processing unit), various storage devices such as RAM (random access memory) and ROM (read-only memory), timers (counters), A / D conversion circuits, D / A conversion circuits, and input / output (I / F) circuits via a bus. In this embodiment, the control unit 11 is packaged as an IC (Integrated Circuit), but it is not limited to this.

[0066] The control unit 11 generates a control signal Sd for controlling the drive of the two-phase stepper motor 20, and controls the drive of the two-phase stepper motor 20 through the drive unit 12. Specifically, the control unit 11 generates the control signal Sd for controlling the drive of the two-phase stepper motor 20 so as to alternately and repeatedly perform one-phase excitation of the coil 21 of the two-phase coils 21A and 21B in the two-phase stepper motor 20 and two-phase excitation of the coils 21A and 21B. That is, the control unit 11 controls the switching of the energization of the coils 21A and 21B of the two-phase stepper motor 20 through a 1-2 phase excitation method.

[0067] In the energizing switching control based on the 1-2 phase excitation method of this embodiment, the energizing angle θ, which represents the magnitude of the energizing angle of a coil continuously energized in one direction for a phase, is not fixed and can be set to a desired value. This will be explained in detail below.

[0068] Figure 3 This is a schematic diagram illustrating the power-on switching control of a two-phase stepper motor based on a 1-2 phase excitation mode, used to explain an embodiment of the present invention.

[0069] exist Figure 3 In the diagram, the horizontal axis represents the electric angle. Figure 3 The upper section shows the excitation states of coil 21A of phase A and coil 21B of phase B when the energizing angle θ = 120°. Figure 3 The lower section shows the excitation states of coil 21A of phase A and coil 21B of phase B when the energizing angle θ = 135°. It should be noted that the periods indicated by the reference numerals AP, AN, BP, and BN in the figure represent the state in which voltage is applied to the terminals corresponding to these reference numerals (e.g., terminal AP on the positive side of coil 21A of phase A).

[0070] like Figure 3 As shown in the lower section, when the energizing angle θ is set to 135° in the same way as the conventional 1-2 phase excitation method, the electrical angles of the period of one-phase excitation and the period of two-phase excitation are 45°, and it is necessary to detect the zero-crossing point of the back electromotive force voltage during the period of one-phase excitation with an electrical angle of 45°.

[0071] On the other hand, such as Figure 3 As shown in the upper paragraph, when the energizing angle θ is set to 120°, the electrical angle during the period of one-phase excitation becomes 60°, and the electrical angle during the period of two-phase excitation becomes 30°. That is, compared with the case where the energizing angle θ is set to 135°, when the energizing angle θ is set to 120°, the period of one-phase excitation is extended by 15°, thereby making it easier to detect the zero-crossing point of the back electromotive force voltage.

[0072] Therefore, the motor drive control device 10 of this embodiment is configured to set the energizing angle θ to any value within the range of 90° to 135° (90°≤θ≤135°) so as to detect the zero-crossing point of the back electromotive force voltage during the period of one-phase excitation. The motor drive control device 10 performs energizing switching control of the two-phase stepper motor 20 based on the set value of the energizing angle θ.

[0073] Figure 4 This diagram illustrates the power-on switching control of a two-phase stepper motor implemented by the motor drive control device 10 according to an embodiment of the present invention.

[0074] exist Figure 4 In the accompanying drawings, reference numeral 401 indicates the voltage at terminal AP of coil 21A of phase A relative to terminal AN (hereinafter also referred to as "phase A voltage"), and reference numeral 402 indicates the back electromotive force voltage of coil 21A of phase A. Figure 4 The voltage waveform of coil 21A of phase A is shown when the energizing angle θ = 120° is set and the energizing switching control of the two-phase stepper motor 20 is performed in a 1-2 phase excitation mode.

[0075] like Figure 4 As shown, the control unit 11 switches the energizing state of the two-phase stepper motor 20 by alternately performing one-phase excitation and two-phase excitation. For example, in Figure 4 During the two-phase excitation period from 180° to 210° (electric angle 30°), the A-phase voltage is set to "-Va" to energize the A-phase coil 21A negatively, and the B-phase voltage is set to "-Vb" to energize the B-phase coil 21B negatively. In the next one-phase excitation period from 210° to 270° (electric angle 60°), the A-phase voltage is set to "0", and the A-phase coil 21A is not energized. Meanwhile, the B-phase voltage is continued to be set to "-Vb" to energize the B-phase coil 21B negatively. In the next two-phase excitation period from 270° to 300° (electric angle 30°), the A-phase voltage is set to "+Va" to energize the A-phase coil 21A positively, and the B-phase voltage is continued to be set to "-Vb" to energize the B-phase coil 21B negatively.

[0076] Here, the periods for single-phase excitation and two-phase excitation of the two-phase stepper motor 20 are determined based on the back electromotive force voltage generated in coil 21A of phase A or coil 21B of phase B and the set energizing angle θ. That is, in motor unit 1, the periods for single-phase excitation and two-phase excitation of the two-phase stepper motor 20 are variable periods rather than fixed periods.

[0077] First, the excitation period of one phase of the two-phase stepper motor 20 is determined as follows.

[0078] The excitation period of one phase of the two-phase stepper motor 20 is determined based on the back electromotive force voltage generated by the non-excited coil 21 on the other side when one coil 21 is energized.

[0079] Specifically, the control unit 11 generates a control signal Sd based on the detection result of the zero-crossing point of the back electromotive force voltage generated in the non-excited coil 21 during the one-phase excitation period, so as to switch the excitation state of the two-phase stepper motor 20 from one-phase excitation to two-phase excitation.

[0080] For example, such as Figure 4 As shown, during the period from electrical angle 210° to electrical angle 270° during one-phase excitation, after the coil 21A of the non-excited A-phase generates a positive spike voltage, a back electromotive force voltage synchronized with the rotation of the rotor of the two-phase stepper motor 20 is generated. Then, when the control unit 11 detects that the back electromotive force voltage of the coil 21A of phase A reaches 0V at time ta (zero crossing), it generates a control signal Sd to switch from one-phase excitation to two-phase excitation.

[0081] Next, the two-phase excitation period of the two-phase stepper motor 20 is determined in the following manner.

[0082] As described above, during the period when the two-phase stepper motor 20 is energized in one phase, a back electromotive force voltage is generated in the non-energized coil 21. On the other hand, during the period when the two-phase stepper motor 20 is energized in two phases (e.g., Figure 4 During the periods of electrical angles 180° to 210° and 270° to 300°, coil 21A of phase A and coil 21B of phase B are energized together. Therefore, the back electromotive force voltage of either coil 21A or coil 21B cannot be measured. Consequently, the timing of switching from two-phase energization to one-phase energization cannot be determined based on the back electromotive force voltage of coil 21 as it is when switching from one-phase energization to two-phase energization.

[0083] Therefore, the control unit 11 determines the period of two-phase excitation based on the elapsed time of each unit angle when the two-phase stepper motor 20 is being energized and the preset energizing angle θ.

[0084] Specifically, the control unit 11 determines the period of two-phase excitation, i.e., the target energizing time T2n, based on the elapsed time per unit angle when the two-phase stepper motor 20 is being energized. The target energizing time T2n can be determined, for example, by the first method or the second method shown below.

[0085] The first method is to measure the excitation period of one phase and use the measured period to calculate the target energizing time T2n.

[0086] Figure 5 This is a diagram illustrating the method for determining the target energizing time of two-phase excitation based on the first method in this embodiment.

[0087] exist Figure 5 In the diagram, the horizontal axis represents time and electrical angle. Furthermore, in... Figure 5 The upper section shows the energizing state of phase A. Figure 5 The lower section shows the energized state of phase B. In Figure 5 In the diagram, T1n represents the period of the nth (n is an integer greater than or equal to 1) single-phase excitation, T1n-1 represents the period of the (n-1)th single-phase excitation, T2n represents the period of the nth two-phase excitation, and T2n-1 represents the period of the (n-1)th two-phase excitation.

[0088] exist Figure 5 In the diagram, when the energizing angle is set to θ, the electrical angles corresponding to the periods T1n-1 and T1n of single-phase excitation are expressed as (180°-θ). Furthermore, the electrical angles corresponding to the periods T2n-1 and T2n of two-phase excitation are expressed as (θ-90°).

[0089] like Figure 5 As shown, the control unit 11 first measures the excitation period T1n of one phase. Then, the control unit 11 calculates the elapsed time per unit angle based on the measured value of the excitation period T1n and the magnitude of the electrical angle (180°-θ) corresponding to the excitation period T1n. Based on the calculated elapsed time and the set energizing angle θ, the control unit 11 calculates the target energizing time T2n for the next two-phase excitation.

[0090] For example, the control unit 11 calculates the target energization time T2n based on the following formula (1).

[0091] [Formula 1]

[0092]

[0093] In the above formula (1), "T1n / (180°-θ)" represents the elapsed time per unit angle when the two-phase stepper motor 20 is being energized by one phase, that is, the time required for the electrical angle to advance by a unit angle (1°) within the period T1n of one-phase energization. In addition, (θ-90°) is the electrical angle corresponding to the period of two-phase energization.

[0094] For example, when the current-carrying angle θ is 120°, formula (1) is expressed as formula (2) below.

[0095] [Formula 2]

[0096]

[0097] As can be understood from formula (2), the target energizing time (the period of two-phase excitation) T2n is the time required for an energizing angle of 30°.

[0098] It should be noted that, alternatively, when the control unit 11 calculates the target energizing time T2n of the two-phase excitation based on the above formula (1), it may measure the period of the one-phase excitation that immediately precedes the two-phase excitation and use that period as the measured value of the one-phase excitation period T1n. Alternatively, it may measure the periods of multiple one-phase excitations that precede the two-phase excitation and use the average value of the multiple measured periods as the measured value of the one-phase excitation period T1n.

[0099] Here, the average value of the multiple single-phase excitation periods can be a simple average value, or it can be calculated by weighting the multiple single-phase excitation periods performed before the two-phase excitation, and setting the target energizing time T2n based on this average value. For example, it is also possible to calculate the average value by weighting the periods of each single-phase excitation in such a way that the closer the two-phase excitation is to the calculation purpose of the target energizing time T2n, the greater the weight.

[0100] The second method is to measure the time between the zero-crossing points of the back electromotive force voltage and use the measured time to calculate the target energizing time T2n for two-phase excitation.

[0101] The control unit 11 first measures the time between the zero-crossing points of the back electromotive force voltage of the coil 21. Based on the measured value of the time between the zero-crossing points of the back electromotive force voltage and the magnitude of the electrical angle corresponding to the zero-crossing point, the control unit 11 calculates the elapsed time per unit angle, and calculates the target energizing time T2n of the two-phase excitation based on the calculated elapsed time and the set energizing angle θ.

[0102] For example, when the measured value of the time between the zero-crossing points of the back electromotive force voltage is set as T0n, the electrical angle corresponding to the measured time between the zero-crossing points is set as α, the energizing angle is set as θ, and the target energizing time of the two-phase excitation is set as T2n, the control unit 11 calculates the target energizing time T2n of the two-phase excitation based on the following formula (3).

[0103] [Formula 3]

[0104]

[0105] In the above formula (3), T0n / α represents the elapsed time per unit angle when the two-phase stepper motor 20 is being energized. In addition, (θ-90°) represents the electrical angle corresponding to the period of two-phase energization.

[0106] For example, in the case of a two-phase stepper motor 20 with two poles, the electrical angle α between the zero-crossing point of the back electromotive force voltage of coil 21A of phase A and the zero-crossing point of the back electromotive force voltage of coil 21B of phase B is 90°. Here, when the current-carrying angle θ is set to 120°, formula (3) can be expressed as the following formula (4).

[0107] [Formula 4]

[0108]

[0109] As can be understood from formula (4), the target energizing time (the period of two-phase excitation) T2n is the time required for an energizing angle of 30°.

[0110] The control unit 11 determines the target energizing time T2n for two-phase excitation based on the first or second method described above. Furthermore, after two-phase excitation has started and the target energizing time T2n has elapsed, the control unit 11 generates a control signal Sd to switch the excitation state of the two-phase stepper motor 20 from two-phase excitation to one-phase excitation.

[0111] For example, such as Figure 4 As shown, during the period from electrical angle 270° to electrical angle 300° during two-phase excitation, coil 21A of phase A and coil 21B of phase B are energized together, therefore, it is impossible to measure the back electromotive force voltage. Therefore, the control unit 11 generates a control signal Sd at time tb (electric angle 300°) when the target energizing time T2n has elapsed since the start of two-phase excitation at time ta (electric angle 270°) to switch from two-phase excitation to one-phase excitation.

[0112] In the following description, as an example, the case in which the control unit 11 determines the target energizing time T2n of the two-phase excitation by the first method will be explained.

[0113] Figure 6 This is a diagram showing the functional block configuration of the control unit 11 in the motor drive control device according to an embodiment of the present invention.

[0114] like Figure 6 As shown, the control unit 11 has a back electromotive force voltage monitoring unit 111, a zero-crossing detection unit 112, a single-phase excitation period timing unit 113, a two-phase excitation period calculation unit 114, a two-phase excitation period timing unit 115, a storage unit 116, and a control signal generation unit 117 as functional units for implementing the above-described energizing and switching control of the coils 21A and 21B of the two-phase stepper motor 20.

[0115] These functional units, for example, are implemented in the program processing device (microcontroller) that serves as the control unit 11 described above, by the processor performing various operations according to the program stored in the storage device to control peripheral circuits such as the A / D conversion circuit and the timer.

[0116] The back electromotive force voltage monitoring unit 111 is a functional unit that monitors the back electromotive force voltage generated by the coils 21A and 21B in each phase.

[0117] The zero-crossing detection unit 112 is a functional unit used to detect the zero-crossing point of the back electromotive force voltage generated by the coils 21A and 21B of the two-phase stepper motor 20 based on the monitoring results of the back electromotive force voltage monitoring unit 111. When the zero-crossing point of the back electromotive force voltage of the unexcited coil 21 is detected, the zero-crossing detection unit 112 outputs a detection signal Sz indicating that a zero-crossing point has been detected.

[0118] The single-phase excitation period timing unit 113 is a functional unit used to measure the excitation period of one phase of the two-phase stepper motor 20. The single-phase excitation period timing unit 113 can be implemented, for example, by a timer (counter) or the like that constituting the microcontroller described above.

[0119] The single-phase excitation period timing unit 113 starts timing when switching from two-phase excitation to single-phase excitation based on the excitation state of the two-phase stepper motor 20. For example, the single-phase excitation period timing unit 113 starts measuring the single-phase excitation period T1n based on a signal output from the two-phase excitation period timing unit 115 (described later) that indicates the end of the two-phase excitation period.

[0120] When the single-phase excitation period timing unit 113 detects a zero-crossing point of the back electromotive force voltage, it stops timing. For example, the single-phase excitation period timing unit 113 stops measuring the single-phase excitation period T1n based on the detection signal Sz output from the zero-crossing detection unit 112 indicating that a zero-crossing point has been detected, stores the measured value of the single-phase excitation period T1n in the storage unit 116, and outputs a notification signal indicating the end of the single-phase excitation period to the two-phase excitation period calculation unit 114.

[0121] Here, the storage unit 116 may store information on the duration of multiple phase excitations measured by the phase excitation duration timing unit 113, or it may store only the information on the duration of the latest phase excitation.

[0122] Storage unit 116 is a functional unit for storing various data required for energizing switching control of two-phase excitation. Storage unit 116 stores data for calculating the target energizing time T2n of two-phase excitation. For example, the measured value of the one-phase excitation period T1n measured by the one-phase excitation period timing unit 113, the energizing angle θ, and the information of the above formula (1) are stored in storage unit 116.

[0123] The two-phase excitation period calculation unit 114 is a functional unit used to calculate the target energizing time T2n of the two-phase excitation of the two-phase stepper motor 20. The two-phase excitation period calculation unit 114 calculates the target energizing time T2n of the two-phase excitation based on the switching from one-phase excitation to two-phase excitation of the excitation state of the two-phase stepper motor 20.

[0124] The two-phase excitation period calculation unit 114 reads the data required to calculate the target energizing time T2n of the two-phase excitation from the storage unit 116 based on the signal indicating the end of the one-phase excitation period output from the one-phase excitation period timing unit 113, and calculates the target energizing time T2n. For example, the two-phase excitation period calculation unit 114 reads the value of the energizing angle θ, the measured value of the one-phase excitation period (T1n), and the information of the above formula (1) from the storage unit 116, performs a calculation based on the above formula (1), calculates the target energizing time T2n, and stores it in the storage unit 116.

[0125] After calculating the target energizing time T2n, the two-phase excitation period calculation unit 114 instructs the two-phase excitation period timing unit 115 to start the measurement of the two-phase excitation period.

[0126] The two-phase excitation period timing unit 115 is a functional unit used to measure the two-phase excitation period of the two-phase stepper motor 20. The two-phase excitation period timing unit 115 can be implemented, for example, by a timer (counter) or the like that constituting the microcontroller described above.

[0127] The two-phase excitation period timing unit 115 starts measuring the two-phase excitation period according to the measurement start instruction from the two-phase excitation period calculation unit 114. For example, the two-phase excitation period timing unit 115 reads the target energization time T2n from the storage unit 116 and sets it in its own timer according to the measurement start instruction from the two-phase excitation period calculation unit 114, thereby starting the measurement. When the measurement time reaches the target energization time T2n, it outputs a signal indicating the end of two-phase excitation.

[0128] It should be noted that when the first method described above is used as the method for determining the target energizing time T2n of two-phase excitation, the timer provided by the one-phase excitation period timing unit 113 and the timer provided by the two-phase excitation period timing unit 115 will not be used simultaneously. Therefore, in this case, it can also be configured such that only one timer is provided, and the one-phase excitation period timing unit 113 and the two-phase excitation period timing unit 115 share this one timer.

[0129] On the other hand, when the second method described above is used as the method for determining the target energizing time T2n of two-phase excitation, the timer provided in the one-phase excitation period timing unit 113 measures the time between the zero-crossing points of the back electromotive force voltage, and the timer provided in the two-phase excitation period timing unit 115 measures the period of two-phase excitation. Therefore, there will be a period during which each timer of the one-phase excitation period timing unit 113 and the two-phase excitation period timing unit 115 is used simultaneously. Therefore, in this case, the one-phase excitation period timing unit 113 and the two-phase excitation period timing unit 115 cannot share a single timer, and thus each needs to have its own timer.

[0130] The control signal generation unit 117 is a functional unit that generates control signals Sd for controlling the drive of the two-phase stepper motor 20. The control signal generation unit 117 can be implemented, for example, by peripheral circuits such as program processing and input / output (I / F) circuits implemented by the processor constituting the microcontroller described above.

[0131] The control signal generation unit 117 uses the control signal Sd to indicate the switching between one-phase excitation and two-phase excitation of the two-phase stepper motor 20.

[0132] In single-phase excitation, the control signal generation unit 117 generates a control signal Sd based on the detection result of the zero-crossing point of the back electromotive force voltage detected by the zero-crossing point detection unit 112, so as to switch the excitation state of the two-phase stepper motor 20 from single-phase excitation to two-phase excitation. For example, the control signal generation unit 117 generates a control signal Sd based on the detection signal Sz of the zero-crossing point detection unit 112, so as to switch the excitation state of the two-phase stepper motor 20 from single-phase excitation to two-phase excitation.

[0133] It should be noted that, alternatively, the control signal generation unit 117 may generate a control signal Sd based on the signal indicating the end of one-phase excitation output from the timing unit 113 during one-phase excitation, rather than based on the detection signal Sz from the zero-crossing detection unit 112, so as to switch the excitation state of the two-phase stepper motor 20 from one-phase excitation to two-phase excitation.

[0134] Furthermore, when the measurement time measured by the two-phase excitation period timing unit 115 reaches the target energizing time T2n during two-phase excitation, the control signal generation unit 117 generates a control signal Sd to switch the excitation state of the two-phase stepper motor 20 from two-phase excitation to single-phase excitation. For example, the control signal generation unit 117 generates the control signal Sd based on the signal indicating the end of two-phase excitation output from the two-phase excitation period timing unit 115, so as to switch the excitation state of the two-phase stepper motor 20 from two-phase excitation to single-phase excitation.

[0135] The drive unit 12 (motor drive unit 121) switches the power on of the two-phase stepper motor 20 based on the control signal Sd output from the control signal generation unit 117 using the method described above.

[0136] Figure 7 This is a flowchart illustrating a specific example of the process of power-on switching control of a two-phase stepper motor 20 implemented by the motor drive control device 10 of this embodiment.

[0137] For example, the motor drive control device 10 determines whether a drive command for the two-phase stepper motor 20 is input from an external host device after the power is turned on (step S1). If no drive command is input (step S1: no), the motor drive control device 10 stands by until a drive command is input.

[0138] On the other hand, when a drive command is input (step S1: Yes), the motor drive control device 10 starts driving the two-phase stepper motor 20. First, the motor drive control device 10 determines whether the next excitation state to be changed by the two-phase stepper motor 20 is single-phase excitation (step S2). Here, as an example, the case of initial single-phase excitation of phase A after power is turned on will be explained.

[0139] In step S2, the excitation state to be switched to one-phase excitation of phase A (step S2: Yes). Therefore, the motor drive control device 10 drives the two-phase stepper motor 20 by one-phase excitation (step S3). For example, the control signal generation unit 117 generates a control signal Sd and provides it to the drive unit 12 to apply the phase A voltage "+Va" to the coil 21A of phase A of the two-phase stepper motor 20 and make the phase B voltage of the coil 21B of phase B "0".

[0140] Furthermore, the motor drive control device 10 begins timing the period of one phase excitation (step S4). Specifically, the one-phase excitation period timing unit 113 begins measuring the period T1n of one phase excitation.

[0141] Next, the motor drive control device 10 monitors the back electromotive force voltage of the unexcited coil 21 of the two-phase stepper motor 20 (step S5).

[0142] Next, the motor drive control device 10 determines whether a zero-crossing point of the back electromotive force voltage of the unexcited coil 21 is detected (step S6). For example, the zero-crossing detection unit 112 determines whether a zero-crossing point of the back electromotive force voltage is generated in the unexcited coil 21 based on the monitoring results of the back electromotive force voltage monitoring unit 111.

[0143] It should be noted that the processes in steps S3 to S5 are not limited to the above order, and can also be performed simultaneously.

[0144] If no zero-crossing of the back EMF voltage is detected (step S6: No), the zero-crossing detection unit 112 continues to monitor the generation of the zero-crossing of the back EMF voltage. If a zero-crossing of the back EMF voltage is detected (step S6: Yes), the motor drive control device 10 stops measuring the period T1n of one phase excitation (step S7). Specifically, the zero-crossing detection unit 112 outputs a detection signal Sz indicating that a zero-crossing of the back EMF voltage has been detected, the one-phase excitation period timing unit 113 stops timing the one-phase excitation period T1n based on the detection signal Sz, stores the measured value of the one-phase excitation period T1n in the storage unit 116, and outputs a signal indicating the end of one-phase excitation.

[0145] Next, the motor drive control device 10 returns to step S2 to determine whether the excitation state to be changed next is single-phase excitation (step S2).

[0146] Here, the preceding excitation state is single-phase excitation. Therefore, the motor drive control device 10 determines that the next excitation state to be changed is two-phase excitation (step S2: no), and switches the excitation state of the two-phase stepper motor 20 from single-phase excitation to two-phase excitation (step S8). For example, the control signal generation unit 117 generates a control signal Sd based on the detection signal Sz output from the zero-crossing detection unit 112 and provides it to the drive unit 12 so as to apply the A-phase voltage "+Va" to the A-phase coil 21A and the B-phase voltage "+Vb" to the B-phase coil 21B.

[0147] Next, the motor drive control device 10 calculates the target energizing time T2n for the two-phase excitation (step S9). Specifically, as described above, the two-phase excitation period timing unit 115 reads the value of the energizing angle θ, the measured value of the one-phase excitation period (T1n), and the information of the above formula (1) from the storage unit 116 based on the notification signal output from the one-phase excitation period timing unit 113 indicating the end of the one-phase excitation period T1n, and calculates the target energizing time T2n based on the above formula (1) and stores it in the storage unit 116.

[0148] Next, the motor drive control device 10 measures the period of two-phase excitation based on the target energizing time T2n calculated in step S9 (step S10). For example, the two-phase excitation period timing unit 115 reads the target energizing time T2n from the storage unit 116 and sets it in its own timer according to the measurement start instruction from the two-phase excitation period calculation unit 114, thereby starting the timing.

[0149] It should be noted that the processes in steps S8 to S10 are not limited to the above order, and can also be performed simultaneously.

[0150] Next, the motor drive control device 10 determines whether the target energizing time T2n has elapsed since the start of the two-phase excitation (step S11). If the target energizing time T2n has not elapsed (step S11: no), the motor drive control device 10 continues to measure the duration of the two-phase excitation.

[0151] On the other hand, when the target energizing time T2n has elapsed (step S11: Yes), the motor drive control device 10 stops measuring the two-phase excitation period (step S12). Specifically, when the two-phase excitation period timing unit 115 detects that the measuring time has reached the target energizing time T2n, it stops timing the two-phase excitation period and outputs a signal indicating the end of two-phase excitation.

[0152] Afterwards, the motor drive control device 10 returns to step S2 and repeatedly executes the above-mentioned steps S2 to S12 until a stop command for the two-phase stepper motor 20 is input from the host device, thereby alternately switching between one-phase excitation and two-phase excitation to drive the two-phase stepper motor 20.

[0153] In the present embodiment, the motor drive control device 10 can set an energizing angle θ, which represents the magnitude of the energizing angle at which the coil 21 of one phase of the two-phase stepper motor 20 is continuously energized in one direction. When the motor drive control device 10 controls the energizing of the two-phase stepper motor 20 in a 1-2 phase excitation mode, it determines the period of one-phase excitation based on the back electromotive force voltage generated in the coil 21 during one-phase excitation and in the non-excited phase, and determines the period of two-phase excitation based on the elapsed time of each unit angle when the two-phase stepper motor 20 is being energized and the set energizing angle θ.

[0154] In conventional 1-2 phase excitation methods, the energizing angle θ is fixed at 135°, and the magnitude of the energizing angle corresponding to each period of single-phase and two-phase excitation is 45°. In contrast, the motor drive control device 10 of this embodiment can set the energizing angle θ to a desired value within, for example, the range of 90°≤θ≤135°.

[0155] Therefore, an appropriate energizing angle θ can be selected based on the inductance of the coil 21 of the two-phase stepper motor 20, the magnitude of the load, etc., so that the zero-crossing point of the back electromotive force voltage can be detected during the excitation period of one phase. For example, as described above, by setting the energizing angle θ = 120°, the electrical angle corresponding to the excitation period of one phase becomes 60°. Therefore, compared with the case where the energizing angle θ is fixed at 135° as in the past, the excitation period of one phase can be extended by an electrical angle of 15° (=60°-45°), thereby making it easier to detect the zero-crossing point of the back electromotive force voltage.

[0156] Therefore, the motor drive control device 10 according to this embodiment can realize stable power-on switching of the two-phase stepper motor 20 based on the 1-2 phase excitation mode.

[0157] Furthermore, in the motor drive control device 10 of this embodiment, the control unit 11 generates a control signal Sd based on the detection result of the zero-crossing point of the back electromotive force voltage generated in the non-excited coil 21 during the period of one-phase excitation, so as to switch the excitation state of the two-phase stepper motor 20 from one-phase excitation to two-phase excitation. The target energizing time T2n is determined based on the elapsed time per unit angle and the energizing angle θ. After the start of two-phase excitation and after the target energizing time T2n has elapsed, the control signal Sd is generated to switch the excitation state of the two-phase stepper motor 20 from two-phase excitation to one-phase excitation.

[0158] Therefore, the two-phase stepper motor 20 can be driven in a manner that follows the load variation of the two-phase stepper motor 20 during the period of single-phase excitation. Furthermore, the period of two-phase excitation is determined based on the elapsed time per unit angle and the energizing angle θ when the two-phase stepper motor 20 is being energized; therefore, the two-phase stepper motor 20 can be driven in a manner that follows the load variation even during the period of two-phase excitation. That is, according to the motor drive control device 10, control can be achieved to vary the speed of the two-phase stepper motor 20 in a way that generates an appropriate torque corresponding to the load of the two-phase stepper motor 20.

[0159] Furthermore, in the motor drive control device 10, the control unit 11 measures the period T1n of one-phase excitation. The elapsed time per unit angle is obtained by dividing the measured value of the period T1n of one-phase excitation by the magnitude of the electrical angle corresponding to the period T1n of that one-phase excitation. More specifically, the control unit 11 calculates the target energizing time T2n of two-phase excitation based on the above formula (1).

[0160] Therefore, the elapsed time per unit angle can be calculated based on the rotor speed of the two-phase stepper motor 20 during the actual one-phase excitation period. Thus, an appropriate two-phase excitation period corresponding to the load state (speed) of the two-phase stepper motor 20 can be set, enabling more stable power-on switching.

[0161] Alternatively, in the motor drive control device 10, the control unit 11 may measure the time between the zero-crossing points of the back electromotive force voltage instead of the measurement period T1n of one-phase excitation, and the elapsed time per unit angle may be obtained by dividing the measured value of the time between the zero-crossing points by the magnitude of the electrical angle between the zero-crossing points. That is, the control unit 11 may calculate the target energizing time T2n of the two-phase excitation based on the above formula (3).

[0162] Therefore, by setting an appropriate two-phase excitation period that corresponds to the actual load state of the two-phase stepper motor 20, just as the elapsed time per unit angle can be calculated by measuring the excitation period T1n of one phase, a more stable power-on switching can be achieved.

[0163] Alternatively, in the motor drive control device 10, the control unit 11 measures the period of one-phase excitation immediately preceding the two-phase excitation and uses this period as the measured value of the one-phase excitation period to calculate the target energizing time T2n of the two-phase excitation. This allows the two-phase excitation period to quickly follow changes in the load of the two-phase stepper motor 20.

[0164] Alternatively, in the motor drive control device 10, the control unit 11 can measure the duration of multiple single-phase excitations prior to two-phase excitation and use the average of the measured durations as the measured value of the single-phase excitation duration to calculate the target energizing time T2n for two-phase excitation. This allows the duration of two-phase excitation to slowly follow the load variation of the two-phase stepper motor 20.

[0165] Extension of Implementation Methods

[0166] The invention made by the inventors has been specifically described above based on the embodiments, but the invention is not limited thereto, and various modifications can be made without departing from its spirit.

[0167] For example, in the above embodiment, a case is illustrated where the two-phase stepper motor 20 has a rotor with two poles, but the number of poles of the rotor is not particularly limited.

[0168] The motor unit 1 in the above embodiments is not limited to Figure 1 The disclosed configuration. For example, in addition to the motor drive unit 121 described above, the drive unit 12 may also have other circuits such as a current detection circuit for detecting the coil current of coils 21A and 21B.

[0169] Furthermore, the flowchart above illustrates one example of an action and is not limiting. That is, the steps shown in each diagram of the flowchart are specific examples and are not limited to that process. For example, the order of some processes can be changed, other processes can be inserted between processes, and some processes can be performed in parallel.

[0170] Explanation of reference numerals in the attached figures

[0171] 1: Motor unit;

[0172] 10: Motor drive control device;

[0173] 11: Control Department;

[0174] 12: Drive unit;

[0175] 20: Two-phase stepper motor;

[0176] 21: Coil;

[0177] 21A: The coil for phase A;

[0178] 21B: The coil for phase B;

[0179] 22: Rotor;

[0180] 22N: N pole;

[0181] 22S: S pole;

[0182] 111: Back EMF voltage monitoring unit;

[0183] 112: Zero-crossing detection department;

[0184] 113: Timing unit during one-phase excitation;

[0185] 114: Calculation unit during two-phase excitation;

[0186] 115: Timing unit during two-phase excitation;

[0187] 116: Storage Department;

[0188] 117: Control signal generation unit;

[0189] 121: Motor drive unit;

[0190] Sd: Control signal;

[0191] Sz: Detection signal;

[0192] T1n: The period of one phase of excitation;

[0193] T2n: Target energizing time (the period of two-phase excitation);

[0194] AP: The positive terminal of the coil in phase A;

[0195] AN: The terminal on the negative side of the coil of phase A;

[0196] BP: The positive terminal of the B-phase coil;

[0197] BN: The terminal on the negative side of the B-phase coil.

Claims

1. A motor drive control device, comprising: The control unit generates control signals for controlling the drive of the two-phase stepper motor, so as to alternately and repeatedly perform one-phase excitation of the coil that excites one phase of the two-phase coils in the two-phase stepper motor and two-phase excitation of the coil that excites both phases of the two-phase coils; and The drive unit drives the two-phase coils based on the control signal. The control unit can set the energizing angle, which represents the magnitude of the energizing angle for unidirectional continuous energizing of the coil of one phase. The control unit determines the period for one-phase excitation based on the back electromotive force voltage generated by the coil in the non-excited phase during one-phase excitation, and determines the period for two-phase excitation based on the elapsed time of each unit angle when the two-phase stepper motor is being energized and the energizing angle.

2. The motor drive control device according to claim 1, characterized in that, The control unit generates the control signal based on the detection result of the zero-crossing point of the back electromotive force voltage generated by the coil during the non-excited period of the one-phase excitation, so as to switch the excitation state of the two-phase stepper motor from the one-phase excitation to the two-phase excitation. The control unit determines the target energizing time based on the elapsed time of each unit angle and the energizing angle, and generates the control signal after the two-phase excitation starts and the target energizing time has elapsed, so as to switch the excitation state of the two-phase stepper motor from the two-phase excitation to the one-phase excitation.

3. The motor drive control device according to claim 2, characterized in that, The control unit measures the period of excitation of one phase. The elapsed time per unit angle is the value obtained by dividing the measured value of the period of one phase excitation by the magnitude of the electrical angle corresponding to the period of one phase excitation.

4. The motor drive control device according to claim 3, characterized in that, When the measured value during the excitation of one phase is set as T1n, the energizing angle is set as θ, and the target energizing time is set as T2n, the target energizing time is calculated based on the following formula (A). [Formula 1] 。 5. The motor drive control device according to claim 3 or 4, characterized in that, The control unit measures the period of the one-phase excitation that occurs immediately before the two-phase excitation and sets the period as the measured value of the one-phase excitation period.

6. The motor drive control device according to claim 3 or 4, characterized in that, The control unit measures the duration of multiple phase excitations performed before the two-phase excitation and sets the average of the measured durations as the measured value of the duration of the phase excitation.

7. The motor drive control device according to claim 2, characterized in that, The control unit measures the time between the zero-crossing points of the back electromotive force voltage. The elapsed time per unit angle is the measured value of the time between the zero crossings divided by the magnitude of the electrical angle between the zero crossings.

8. The motor drive control device according to claim 7, characterized in that, When the measured value of the time between the zero-crossing points of the back electromotive force voltage is set as Tz, the magnitude of the measured electrical angle between the zero-crossing points is set as α, the energizing angle is set as θ, and the target energizing time is set as T2n, the control unit calculates the target energizing time based on the following formula (B). [Formula 2] 。 9. The motor drive control device according to any one of claims 1 to 4, 7, and 8, characterized in that, The current-carrying angle is a value of 90° or higher and 135° or lower.

10. A motor unit, characterized in that, have: The motor drive control device according to any one of claims 1 to 9; and The two-phase stepper motor.

11. A motor drive control method for controlling the drive of a two-phase stepper motor via a motor drive control device, the motor drive control method comprising: In the first step, the motor drive control device generates a control signal for controlling the drive of the two-phase stepper motor, so as to alternately and repeatedly perform one-phase excitation of the coil that excites one phase of the two-phase coil in the two-phase stepper motor and two-phase excitation of the coil that excites both phases of the two-phase coil. as well as In the second step, the motor drive control device drives the two-phase coil based on the control signal. The motor drive control device sets an energizing angle, which represents the magnitude of the unidirectional continuous energizing angle of the coil of one phase. The first step includes: The third step is to determine the period for performing the one-phase excitation based on the back electromotive force voltage generated in the coil during the non-excitation phase of the one-phase excitation. as well as The fourth step is to determine the duration of the two-phase excitation based on the elapsed time of each unit angle when the two-phase stepper motor is being energized and the energizing angle.

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