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

Abstract

To provide a motor drive controller capable of reliably bringing the rotational speed of a motor closer to a target rotational speed.SOLUTION: A motor drive controller 2 includes: a drive circuit 6 that applies an AC voltage converted by switching DC voltage VDD to a coil of a motor 3 based on a drive control signal Sd for controlling the drive of the motor 3; and a control circuit 5 that performs PWM control to generate a PWM signal as drive control signal Sd so that the rotation speed Sr of motor 3 matches the target rotation speed Stg and a sinusoidal current flows through the coil. The control circuit 5 is configured so as to, when the rotation speed Sr has not reached the target rotation speed Stg, increase the modulation degree indicating the ratio of the AC voltage command value to the DC voltage VDD to generate the PWM signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor drive control device, a motor unit, and a motor drive control method. [Background technology]

[0002] Conventionally, a PWM (Pulse Width Modulation) control method has been known as a motor drive control method in which a PWM signal is generated in accordance with the rotation speed of the motor so that a sinusoidal current flows through the motor coil, and the motor is driven (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-5349 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional PWM control methods, even if a PWM signal is generated with an optimal lead angle value to maximize the amount of motor operation, the motor rotation speed may not reach the target rotation speed depending on, for example, the magnitude of the motor load.

[0005] The present invention is intended to solve the above-mentioned problems, and has an object to more reliably bring the rotation speed of the motor closer to the target rotation speed. [Means for solving the problem]

[0006] A motor drive control device according to a representative embodiment of the present invention includes a drive circuit that applies an AC voltage converted by switching a DC voltage to a coil of the motor based on a drive control signal for controlling the drive of the motor, and a control circuit that performs PWM control to generate a PWM signal as the drive control signal so that the rotational speed of the motor matches a target rotational speed and a sinusoidal current flows through the coil, and is characterized in that, when the rotational speed has not reached the target rotational speed, the control circuit increases a modulation degree indicating the ratio of a command value of the AC voltage to the DC voltage to generate the PWM signal. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to more reliably bring the rotation speed of the motor closer to the target rotation speed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing the configuration of a motor unit equipped with a motor drive control device according to an embodiment; [Figure 2] 3 is a diagram showing an example of a current flowing through a coil of a motor driven by the motor drive control device according to the embodiment; FIG. [Figure 3] FIG. 10 is a diagram showing an example of a modulation waveform table in which the modulation degree is a reference value (100%). [Figure 4A] FIG. 10 is a diagram showing an example of a modulation waveform table when the modulation degree is set to a value (105%) greater than the reference value (100%). [Figure 4B] FIG. 10 is a diagram showing an example of a modulation waveform table when the modulation degree is set to a value (110%) greater than the reference value (100%). [Figure 4C] FIG. 10 is a diagram showing an example of a modulation waveform table when the modulation degree is set to a value (115%) greater than the reference value (100%). [Figure 4D] FIG. 10 is a diagram showing an example of a modulation waveform table when the modulation degree is set to a value (120%) greater than the reference value (100%). [Figure 5]FIG. 4 is a diagram illustrating an example of a processing flow related to generation of a PWM signal. [Figure 6] 5 is a diagram showing an example of changes in the rotation speed of the motor 3 when the modulation degree of PWM control is changed by the motor drive control device according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. Overview of the embodiment First, a typical embodiment of the invention disclosed in this application will be outlined. In the following description, for example, reference numerals in the drawings corresponding to components of the invention are written in parentheses.

[0010] [1] A motor drive control device (2) according to a representative embodiment of the present invention comprises a drive circuit (6) that applies an AC voltage converted by switching a DC voltage (VDD) to a coil of the motor based on a drive control signal (Sd) for controlling the drive of the motor (3), and a control circuit (5) that performs PWM control to generate a PWM signal as the drive control signal so that a rotation speed (Sr) of the motor matches a target rotation speed (Stg) and a sinusoidal current flows through the coil, and the control circuit is characterized in that, when the rotation speed has not reached the target rotation speed, it increases a modulation degree indicating the ratio of a command value of the AC voltage to the DC voltage to generate the PWM signal.

[0011] [2] In the motor drive control device described in [1] above, the control circuit calculates a modulation factor (Sm) representing an operation amount for making a deviation (Sdf) of the rotation speed from the target rotation speed zero in the PWM control, and the control circuit may increase the modulation factor in stages from a reference value when the modulation factor is a maximum value (e.g., 100%) and the rotation speed has not reached the target rotation speed.

[0012] [3] In the motor drive control device described in [2] above, the control circuit may set the modulation degree to a value higher than the reference value (for example, 105% to 120%), and then, if the modulation magnification is smaller than the maximum value, gradually reduce the modulation degree to the reference value.

[0013] [4] In the motor drive control device described in [2] or [3] above, the control circuit includes an electrical angle calculation unit (12) that calculates the electrical angle (Sφ) of the motor, and a PWM signal generation unit (13) that includes modulation waveform tables (170-171) that determine the duty ratio of the PWM signal for each electrical angle according to the modulation factor, adjusts the duty ratio corresponding to the electrical angle determined based on the modulation waveform table according to the modulation magnification, and generates the PWM signal having the adjusted duty ratio, and when changing the modulation factor, the PWM signal generation unit may generate the PWM signal using the modulation waveform tables (171-174) that correspond to the modulation factor after the change.

[0014] [5] In the motor drive control device described in [4] above, the PWM signal generation unit includes a deviation calculation unit (14) that calculates the deviation, a modulation magnification calculation unit (15) that calculates the modulation magnification based on the deviation, a storage unit (17) that stores a basic modulation waveform table (170) that is the modulation waveform table when the modulation index is the reference value, and information (171A to 174A) of the difference between the basic modulation waveform table and the modulation waveform table when the modulation index is a value different from the reference value, and and a signal generating unit (16) that adjusts the duty ratio of the PWM signal for each electrical angle in the table based on the modulation magnification and generates the PWM signal having the adjusted duty ratio, wherein when the modulation index is changed to a value different from the reference value, the signal generating unit may generate the modulation waveform table (171 to 174) when the modulation index is a value different from the reference value based on the modulation waveform table when the modulation index is the reference value and information on the difference, which are stored in the storage unit.

[0015] [6] In the motor drive control device described in [4] above, the PWM signal generation unit includes a deviation calculation unit (14) that calculates the deviation, a modulation magnification calculation unit (15) that calculates the modulation magnification based on the deviation, a memory unit (17) that stores a plurality of modulation waveform tables (171 to 174) having different modulation indices, and a signal generation unit (16) that adjusts the duty ratio of the PWM signal for each electrical angle in the modulation waveform table based on the modulation magnification and generates the PWM signal having the adjusted duty ratio, and when changing the modulation indices, the signal generation unit may select the modulation waveform table corresponding to the changed modulation indices from the plurality of modulation waveform tables (171 to 174) stored in the memory unit to generate the PWM signal.

[0016] [7] A motor unit (1) according to a representative embodiment of the present invention is characterized by comprising the motor drive control device (2) described in any one of [1] to [6] above, and the motor (3).

[0017] [8] A motor drive control method according to a representative embodiment of the present invention includes a first step (S1 to S8) of performing PWM control to generate a PWM signal so that the rotational speed of a motor coincides with a target rotational speed and a sinusoidal current flows through the coil of the motor, and a second step of applying to the coil an AC voltage converted by switching a DC voltage based on the PWM signal generated in the first step, wherein the first step includes steps (S1 to S4, S7, S8) of increasing a modulation degree indicating the ratio of a command value of the AC voltage to the DC voltage when the rotational speed has not reached the target rotational speed, thereby generating the PWM signal.

[0018] 2. Specific examples of embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, components common to the embodiments will be designated by the same reference numerals, and repeated description will be omitted.

[0019] First Embodiment FIG. 1 is a diagram showing the configuration of a motor unit equipped with a motor drive control device according to an embodiment.

[0020] The motor unit 1 shown in FIG. 1 includes a motor 3, a position detector 4, and a motor drive control device 2.

[0021] The motor 3 is a motor having at least one coil. For example, the motor 3 is a brushless DC motor having three-phase (U-phase, V-phase, and W-phase) coils (windings). The motor 3 functions as a fan motor, for example, by connecting an impeller (not shown) to the output shaft of the motor 3.

[0022] The position detector 4 is a device that generates a position detection signal Sh that corresponds to the rotation of the rotor of the motor 3. The position detector 4 includes, for example, a Hall element. In the motor unit 1 according to this embodiment, a Hall element is provided at a position corresponding to each of the coils of the U phase, V phase, and W phase of the motor 3. The Hall element detects the magnetic poles of the rotor and outputs a Hall signal whose voltage changes according to the rotation of the rotor. The Hall signal output from the position detector 4 is, for example, a pulse signal, and is input to the motor drive control device 2 as the position detection signal Sh.

[0023] The motor drive control device 2 is a device that controls the driving of the motor 3. The motor drive control device 2 drives the motor 3 by, for example, performing PWM control to generate a PWM signal so that the rotation speed Sr of the motor 3 matches the target rotation speed Stg and so that a sinusoidal current flows through the coil of the motor 3.

[0024] The motor drive control device 2 includes a control circuit 5 and a drive circuit 6. The motor drive control device 2 receives a DC voltage from an external DC power supply (not shown). The DC voltage is supplied to a power supply line (not shown) within the motor drive control device 2, for example, via a protection circuit or the like, and is input as a power supply voltage to the control circuit 5 and the drive circuit 6 via the power supply line. Hereinafter, the power supply voltage supplied to the drive circuit 6 will also be referred to as the "DC voltage VDD."

[0025] The drive circuit 6 is a circuit that drives the motor 3 based on a drive control signal Sd output from the control circuit 5. The drive control signal Sd is a signal for controlling the driving of the motor 3, and is, for example, a PWM signal.

[0026] The drive circuit 6 includes, for example, an inverter circuit having a plurality of transistors as switching elements. The drive circuit 6 switches the connection destination of each phase coil of the motor 3 between a DC voltage VDD and ground potential in response to a PWM signal as the drive control signal Sd. Specifically, the drive circuit 6 switches the DC voltage VDD based on the PWM signal as the drive control signal Sd, converting it into an AC voltage, and applies the converted AC voltage to the coil of the motor 3.

[0027] The drive circuit 6 may include a pre-drive circuit for driving each transistor constituting the inverter circuit based on the drive control signal Sd. A sense resistor for detecting the current in the motor coil may be connected to the inverter circuit.

[0028] The control circuit 5 is a circuit for comprehensively controlling the operation of the motor drive control device 2. In this embodiment, the control circuit 5 is a program processing device having a configuration in which a processor such as a CPU, various storage devices such as RAM, ROM, and flash memory, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output interface circuit are interconnected via a bus or dedicated lines. For example, the control circuit 5 is a microcontroller (MCU: Micro Controller Unit).

[0029] The control circuit 5 and the drive circuit 6 may be configured to be packaged as a single semiconductor integrated circuit (IC: Integrated Circuit), or may be configured to be packaged as separate integrated circuits, mounted on a circuit board, and electrically connected to each other on the circuit board.

[0030] The control circuit 5 performs PWM control. That is, the control circuit 5 generates a PWM signal with a duty ratio determined so that the rotation speed Sr of the motor 3 matches the target rotation speed Stg and a sinusoidal current flows through the coils of the motor 3, and outputs the PWM signal as a drive control signal Sd. For example, the control circuit 5 generates a PWM signal so that sinusoidal currents with a phase difference of 120 degrees flow through the U-, V-, and W-phase coils of the motor 3, and outputs the PWM signal to the drive circuit 6 as a drive control signal Sd.

[0031] FIG. 2 is a diagram showing an example of the current flowing through the coil of the motor 3 driven by the motor drive control device 2 according to the embodiment.

[0032] 2 representatively shows the voltage and current related to the U phase among the U, V, and W phases of the motor 3. That is, from the top to the bottom of FIG. 2, the waveform of the position detection signal (Hall signal) Sh, the waveform of the PWM signal for driving the high-side switch of the U-phase inverter circuit (drive circuit 6), the waveform of the PWM signal for driving the low-side switch of the U-phase inverter circuit (drive circuit 6), and the waveform of the current in the U-phase coil (winding) are shown.

[0033] As shown in Fig. 2, the control circuit 5 generates a pulse-width modulated signal (PWM signal) and drives each switch constituting the drive circuit 6 (inverter circuit) so that the rotation speed Sr of the motor 3 matches the target rotation speed Stg and a sinusoidal current flows in the coil. As a result, an AC voltage converted by switching the DC voltage VDD is applied to the coils of each phase of the motor 3. At this time, the average voltage of the coils becomes equivalent to a sinusoidal AC voltage, and as shown in Fig. 2, a sinusoidal current flows in the coils.

[0034] Generally, in PWM control of a motor, the ratio of the amplitude of the AC voltage to be generated to the amplitude of the carrier is called the "modulation degree (modulation rate)." In this embodiment, the modulation degree is defined as the ratio of the command value of the AC voltage to the DC voltage VDD.

[0035] In PWM control, the control circuit 5 determines the pulse width (duty ratio) of the PWM signal in accordance with the deviation Sdf of the rotation speed Sr from the target rotation speed Stg and the electrical angle Sφ so that an equivalent AC voltage (average voltage) in accordance with the set modulation degree is applied to the coil of the motor 3. In addition to the above-mentioned PWM control function, the control circuit 5 also has a function to increase the modulation degree when the rotation speed Sr of the motor 3 has not reached the target rotation speed Stg.

[0036] Specifically, the control circuit 5 calculates a modulation factor Sm that represents the manipulated variable for reducing the deviation Sdf of the rotation speed Sr from the target rotation speed Stg to zero under PWM control, and when the modulation factor Sm is at its maximum value and the rotation speed Sr has not yet reached the target rotation speed Stg, the control circuit 5 increases the modulation factor in stages from a reference value. Alternatively, when the modulation factor Sm is less than the maximum value, the control circuit 5 may decrease the modulation factor in stages to the reference value. A specific example of the configuration of the control circuit 5 for realizing the above-described functions will be described in detail below.

[0037] For example, as shown in FIG. 1, the control circuit 5 includes a drive command analysis unit 10, a rotation speed calculation unit 11, an electrical angle calculation unit 12, and a PWM signal generation unit 13.

[0038] The above-described functional units constituting the control circuit 5 are realized, for example, by program processing of an MCU serving as the control circuit 5. Specifically, a processor constituting the MCU serving as the control circuit 5 performs various calculations in accordance with programs stored in a memory to control the peripheral circuits constituting the MCU, thereby realizing a drive command analysis unit 10, a rotation speed calculation unit 11, an electrical angle calculation unit 12, and a PWM signal generation unit 13.

[0039] The drive command analysis unit 10 receives, for example, a drive command signal Sc output from a higher-level device (not shown) provided outside the motor drive control device 2. The drive command signal Sc is a signal indicating a target value for driving the motor 3, such as a speed command signal indicating a target rotation speed Stg of the motor 3.

[0040] The drive command analyzer 10 analyzes the drive command signal Sc to obtain information on the specified target rotation speed Stg. For example, if the drive command signal Sc is a PWM signal having a duty ratio corresponding to the target rotation speed Stg, the drive command analyzer 10 analyzes the duty ratio of the drive command signal Sc and outputs information on the rotation speed corresponding to the duty ratio as the target rotation speed Stg.

[0041] The rotation speed calculation unit 11 is a functional unit that calculates the actual rotation speed Sr of the motor 3. The rotation speed calculation unit 11 calculates and outputs the rotation speed Sr of the motor 3 based on the position detection signal Sh (e.g., a Hall signal) output from the position detector 4, for example, by a known calculation method.

[0042] The electrical angle calculation unit 12 is a functional unit that calculates the electrical angle Sφ corresponding to the position (rotation angle) of the rotor of the motor 3. The electrical angle calculation unit 12 calculates the electrical angle Sφ of the rotor based on the position detection signal Sh (e.g., a Hall signal) output from the position detector 4, for example, by a known calculation method.

[0043] The PWM signal generating unit 13 is a functional unit that generates a PWM signal as a drive control signal Sd based on the target rotation speed Stg analyzed by the drive command analyzing unit 10, the rotation speed Sr calculated by the rotation speed calculating unit 11, and the electrical angle Sφ calculated by the electrical angle calculating unit 12.

[0044] Here, an outline of a method for generating a PWM signal by the PWM signal generating unit 13 will be described. The PWM signal generating unit 13 has, for example, a modulation waveform table, adjusts the duty ratio corresponding to the electrical angle Sφ calculated based on the modulation waveform table in accordance with the modulation magnification Sm, and outputs a PWM signal having the adjusted duty ratio.

[0045] Here, as described above, the modulation magnification Sm is information indicating the manipulated variable for reducing the deviation Sdf of the rotation speed Sr from the target rotation speed Stg to zero. Specifically, the modulation magnification Sm can be calculated by performing a PID (Proportional-Integral-Differential) control operation so that the deviation Sdf becomes zero. The modulation magnification Sm is, for example, a value in the range of 0% to 100%.

[0046] The modulation waveform table is data that defines the duty ratio of the PWM signal for each electrical angle Sφ according to the modulation degree. In other words, the modulation waveform table is information that defines the duty ratio of the PWM signal required to apply an equivalent AC voltage (average voltage) according to the set modulation degree to the coil for each electrical angle Sφ of the motor 3 (rotor).

[0047] FIG. 3 is a diagram showing an example of a modulation waveform table in which the modulation degree is a reference value (100%). In FIG. 3, the horizontal axis represents the electrical angle Sφ, and the vertical axis represents the duty ratio of the PWM signal. The modulation waveform designated by reference symbol 170 (hereinafter referred to as the "modulation waveform table") represents a modulation waveform (basic modulation waveform) that defines the duty ratio of the PWM signal for each electrical angle Sφ of the motor 3, which is required to apply an equivalent AC voltage (average voltage) with a modulation degree of 100% to the coil when the modulation magnification Sm is set to 100%. The modulation waveform of the modulation waveform table 170 can be calculated, for example, by using the so-called intermediate voltage 1 / 2 superposition method, in which an intermediate voltage of the AC voltage is added as a common-mode voltage to the AC voltage (phase voltage) to be applied to the coil of each phase of the motor 3, and the modulation degree of each phase is calculated. In the following description, the modulation waveform table 170 when the modulation degree is the reference value (100%) and the modulation magnification Sm is 100% is also referred to as the "basic modulation waveform table 170."

[0048] The PWM signal generating unit 13 stores in advance in an internal storage area a basic modulation waveform table 170 including information on the waveforms shown in FIG. 3, and uses the basic modulation waveform table 170 to determine the duty ratio of the PWM signal to be generated based on the modulation magnification Sm calculated based on the rotation speed deviation Sdf and the electrical angle Sφ calculated by the electrical angle calculating unit 12.

[0049] For example, if the modulation magnification Sm calculated based on the rotation speed deviation Sdf is 100%, the PWM signal generating unit 13 reads out the duty ratio corresponding to the electrical angle Sφ calculated by the electrical angle calculating unit 12 from the basic modulation waveform table 170 of FIG. 3 and outputs a PWM signal of the read duty ratio.

[0050] Furthermore, for example, if the modulation magnification Sm calculated based on the rotation speed deviation Sdf is 75%, the PWM signal generating unit 13 reads out the duty ratio corresponding to the electrical angle Sφ from the basic modulation waveform table 170 shown in Fig. 3, adjusts the read-out duty ratio by the modulation magnification Sm (75%), and sets the adjusted duty ratio as the duty ratio of the PWM signal to be generated. For example, the PWM signal generating unit 13 multiplies the duty ratio read out from the basic modulation waveform table 170 by 0.75 (75%) and sets the value as the duty ratio of the PWM signal to be generated. In this way, the PWM signal generating unit 13 determines the duty ratio of the PWM signal based on the basic modulation waveform table 170, the electrical angle Sφ, and the modulation magnification Sm.

[0051] Next, a method for changing the modulation degree in PWM control by the motor drive control device 2 will be described.

[0052] Generally, in PWM control of a motor, to increase the motor rotation speed Sr, it is necessary to increase the effective value of the equivalent AC voltage applied to the motor coil, thereby increasing the effective value of the coil current. The maximum effective value of the equivalent AC voltage applied to the coil is determined by the modulation index.

[0053] However, as mentioned above, depending on the motor load, etc., when the modulation degree in PWM control is set to 100%, even if a PWM signal is generated with an optimal lead angle value so that the motor operation amount (modulation magnification Sm) is maximized, the motor rotation speed Sr may not reach the target rotation speed Stg.

[0054] Therefore, when the rotation speed Sr of the motor does not reach the target rotation speed Stg, the motor drive control device 2 of this embodiment increases the modulation degree in PWM control above a reference value (e.g., 100%), thereby increasing the maximum effective value of the equivalent AC voltage applied to the coil and increasing the rotation speed Sr of the motor 3.

[0055] Specifically, when the rotation speed Sr has not reached the target rotation speed Stg, the PWM signal generating unit 13 generates a PWM signal using a modulation waveform table in which the duty ratio is adjusted so that the modulation degree is higher than a reference value. This will be described in detail below.

[0056] In this embodiment, as an example, the reference value of the modulation degree in PWM control is "100%" and the maximum value of the modulation degree is 120%, but the present invention is not limited to this.

[0057] Figures 4A to 4D are diagrams showing examples of modulation waveform tables when the modulation degree is set to a value greater than the reference value (100%). Specifically, Figure 4A shows an example of a modulation waveform table when the modulation degree is set to a value (105%) greater than the reference value (100%), Figure 4B shows an example of a modulation waveform table when the modulation degree is set to a value (110%) greater than the reference value (100%), Figure 4C shows an example of a modulation waveform table when the modulation degree is set to a value (115%) greater than the reference value (100%), and Figure 4D shows an example of a modulation waveform table when the modulation degree is set to a value (120%) greater than the reference value (100%).

[0058] 4A to 4D, the horizontal axis represents the electrical angle Sφ, and the vertical axis represents the duty ratio of the PWM signal. FIG. 4A shows a modulation waveform table 171 (modulation magnification Sm=100%) in which the duty ratio for each electrical angle Sφ is adjusted so that the modulation degree is 105%. FIG. 4B shows a modulation waveform table 172 (modulation magnification Sm=100%) in which the duty ratio for each electrical angle Sφ is adjusted so that the modulation degree is 110%. FIG. 4C shows a modulation waveform table 173 (modulation magnification Sm=100%) in which the duty ratio for each electrical angle Sφ is adjusted so that the modulation degree is 115%. FIG. 4D shows a modulation waveform table 174 (modulation magnification Sm=100%) in which the duty ratio for each electrical angle Sφ is adjusted so that the modulation degree is 120%.

[0059] When changing the modulation degree, the PWM signal generating unit 13 generates a PWM signal using a modulation waveform table corresponding to the changed modulation degree. For example, the PWM signal generating unit 13 increases the modulation degree from a reference value (100%) to a maximum value (e.g., 120%) in increments of a predetermined amount α (e.g., α=5%).

[0060] For example, when the modulation degree is at a reference value (100%), if the modulation magnification Sm is at the maximum value (100%) and the rotation speed Sr has not reached the target rotation speed Stg, the PWM signal generating unit 13 changes the modulation degree from the reference value to 105% and changes the modulation waveform table to be used, for example, from the basic modulation waveform table 170 shown in FIG. 3 to the modulation waveform table 171 shown in FIG. 4A.

[0061] Next, the PWM signal generating unit 13 reads out the duty ratio corresponding to the electrical angle Sφ calculated by the electrical angle calculating unit 12 from the modulation waveform table 171, adjusts the read-out duty ratio in accordance with the modulation magnification Sm (0% to 100%) using the method described above, and outputs a PWM signal having the adjusted duty ratio. As a result, compared to when the modulation degree is 100%, an equivalent AC voltage having an effective value that is theoretically 1.05 times (105%) is applied to the coil of the motor 3, and the rotation speed Sr of the motor 3 can be further increased.

[0062] Note that because the maximum voltage applied to the coil is limited to the DC voltage VDD, the amplitude of the equivalent AC voltage actually applied to the coil will never be 105% of the DC voltage VDD. In other words, if the modulation degree is set to 100% or higher, the AC voltage applied to the coil will be distorted compared to the sinusoidal voltage at a modulation degree of 100%.

[0063] If, after the modulation degree is set to 105%, the modulation magnification Sm is at its maximum value (100%) and the rotation speed Sr has not yet reached the target rotation speed Stg, the PWM signal generating unit 13 further increases the modulation degree. That is, the PWM signal generating unit 13 changes the modulation degree from 105% to 110% and generates a PWM signal using, for example, the modulation waveform table 172 shown in FIG. 4B. The method of generating the PWM signal in this case is the same as when the modulation degree is 105%.

[0064] In this way, when the modulation factor Sm is at its maximum value and the rotation speed Sr has not yet reached the target rotation speed Stg, the PWM signal generator 13 increases the modulation factor in stages, thereby enabling the rotation speed Sr of the motor 3 to be increased in stages so that it reaches the target rotation speed Stg.

[0065] On the other hand, if a PWM signal is generated with a modulation factor exceeding 100%, the motor 3 tends to vibrate easily. Therefore, the PWM signal generating unit 13 may gradually reduce the modulation factor to a reference value when the modulation magnification Sm is smaller than the maximum value (100%).

[0066] For example, the PWM signal generating unit 13 may set a threshold value Sth of the modulation magnification Sm for switching the modulation degree, and when the modulation magnification Sm becomes equal to or less than the threshold value Sth, reduce the modulation degree in stages to a reference value of 100%. For example, the PWM signal generating unit 13 reduces the modulation degree to the reference value (100%) in increments of a predetermined amount β (for example, 5%). The threshold value Sth of the modulation magnification Sm can be set to any value, but in this embodiment, as an example, the threshold value Sth is set to 95%.

[0067] Specifically, in a state where a PWM signal is generated with a modulation degree of 120%, if the rotation speed Sr of the motor 3 approaches the target rotation speed Stg and the modulation magnification Sm drops to 90%, the PWM signal generation unit 13 detects that the modulation magnification Sm (=90%) is equal to or lower than the threshold value Sth (=95%) and changes the modulation degree from 120% to 115%. That is, the PWM signal generation unit 13 changes from modulation waveform table 174, in which the modulation degree is set to 120%, to modulation waveform table 173, in which the modulation degree is set to 115%, and generates a PWM signal.

[0068] For example, if the modulation scale factor Sm drops to 93% after the modulation degree is reduced to 115%, the PWM signal generating unit 13 detects that the modulation scale factor Sm (=93%) is equal to or less than the threshold value Sth (=95%) and reduces the modulation degree from 115% to 110%. That is, the PWM signal generating unit 13 changes from modulation waveform table 173 with a modulation degree of 115% to modulation waveform table 172 with a modulation degree of 110%, and generates a PWM signal.

[0069] In this way, when the modulation magnification Sm falls below the maximum value, the PWM signal generating unit 13 gradually reduces the modulation degree, thereby making it possible to suppress vibration of the motor 3 after the rotation speed Sr of the motor 3 reaches the target rotation speed Stg.

[0070] Next, a specific example of the configuration of the PWM signal generating unit 13 for realizing the above-mentioned PWM signal generating function and modulation degree adjusting function will be described.

[0071] As shown in FIG. 1, the PWM signal generating unit 13 includes, for example, a deviation calculating unit 14, a modulation magnification calculating unit 15, a signal generating unit 16, and a storage unit 17.

[0072] The deviation calculation unit 14 is a functional unit that calculates a deviation (speed deviation) Sdf of the rotation speed Sr of the motor 3 from the target rotation speed Stg. The deviation calculation unit 14 calculates the deviation Sdf (=Stg-Sr) by, for example, subtracting the rotation speed Sr calculated by the rotation speed calculation unit 11 from the target rotation speed Stg output from the drive command analysis unit 10.

[0073] The modulation magnification calculation unit 15 is a functional unit that calculates the modulation magnification Sm. For example, as described above, the modulation magnification calculation unit 15 calculates the modulation magnification Sm by performing PID control calculation so that the deviation Sdf calculated by the deviation calculation unit 14 becomes zero.

[0074] The storage unit 17 is a functional unit for storing various data and calculation results required to realize the function of generating a PWM signal and the function of adjusting the modulation degree. For example, the storage unit 17 pre-stores a basic modulation waveform table 170 in which the modulation degree becomes a reference value (100%).

[0075] The storage unit 17 also stores data related to modulation waveform tables when the modulation index is a value different from the reference value. The data related to modulation waveform tables when the modulation index is a value different from the reference value is, for example, information on the difference between the basic modulation waveform table 170 and the modulation waveform tables 171-174 when the modulation index is a value different from the reference value (105% to 120%) (hereinafter also referred to as "table difference information"). In other words, the table difference information is information on the difference between the duty ratio for each electrical angle Sφ in the basic modulation waveform table 170 when the modulation index is the reference value (100%) and the duty ratio for each electrical angle Sφ in the modulation waveform tables 171-174 when the modulation index is a value different from the reference value (105% to 120%).

[0076] In this embodiment, for example, as described above, it is assumed that the storage unit 17 stores table difference information 171A to 174A corresponding to four modulation indices greater than the reference value (100%).

[0077] For example, the table difference information 171A is data including the difference in duty ratio for each electrical angle Sφ between the basic modulation waveform table 170 and the modulation waveform table 171 when the modulation degree is 105%. The table difference information 172A is data including the difference in duty ratio for each electrical angle Sφ between the basic modulation waveform table 170 and the modulation waveform table 172 when the modulation degree is 110%. The table difference information 173A is data including the difference in duty ratio for each electrical angle Sφ between the basic modulation waveform table 170 and the modulation waveform table 173 when the modulation degree is 115%. The table difference information 174A is data including the difference in duty ratio for each electrical angle Sφ between the basic modulation waveform table 170 and the modulation waveform table 174 when the modulation degree is 120%.

[0078] The storage unit 17 also stores the threshold value Sth of the modulation magnification Sm described above.

[0079] The signal generating unit 16 is a functional unit that generates a PWM signal based on the modulation magnification Sm calculated by the modulation magnification calculating unit 15 and information stored in the storage unit 17. The signal generating unit 16 has, for example, a modulation waveform table determining unit 18 and a signal output unit 19.

[0080] The modulation waveform table determination unit 18 determines the modulation waveform table to be used to generate a PWM signal according to the driving state of the motor 3. For example, when starting the motor 3, the modulation waveform table determination unit 18 selects the basic modulation waveform table 170 that is set as an initial condition.

[0081] When the modulation magnification Sm is at its maximum value (100%) and the rotation speed Sr has not reached the target rotation speed Stg (deviation Sdf>0), the modulation waveform table determination unit 18 changes the modulation waveform table so that the modulation degree increases stepwise from the reference value (100%).On the other hand, when the modulation magnification Sm calculated by the modulation magnification calculation unit 15 is equal to or lower than a threshold value Sth (for example, 95%), the modulation waveform table determination unit 18 changes the modulation waveform table so that the modulation degree decreases stepwise to the reference value (100%).

[0082] When changing the modulation index to a value different from the reference value, the modulation waveform table determination unit 18 generates modulation waveform tables 171 to 174 corresponding to the changed modulation index based on the basic modulation waveform table 170 and table difference information 171A to 174A stored in the memory unit 17.

[0083] Specifically, the difference in duty ratio for each electrical angle Sφ in the table difference information 171A to 174A corresponding to the changed modulation degree is added to the duty ratio for each electrical angle Sφ in the basic modulation waveform table 170, thereby generating a modulation waveform table corresponding to the changed modulation degree.

[0084] For example, when changing the modulation degree from 100% to 105%, the modulation waveform table determination unit 18 generates a modulation waveform table 171 with a modulation degree of 105% by adding the difference in duty ratio for each electrical angle Sφ stored in the table difference information 171A for a modulation degree of 105% to the duty ratio for each electrical angle Sφ in the basic modulation waveform table 170, and stores the generated modulation waveform table 171 in the storage unit 17.

[0085] The signal output unit 19 generates a PWM signal based on the modulation waveform table determined by the modulation waveform table determination unit 18, the electrical angle Sφ, and the modulation magnification Sm. Specifically, the signal output unit 19 refers to the modulation waveform table determined by the modulation waveform table determination unit 18 and stored in the storage unit 17, adjusts the duty ratio corresponding to the electrical angle Sφ in the modulation waveform table based on the modulation magnification Sm, and generates a PWM signal having the adjusted duty ratio.

[0086] For example, when the modulation depth is 100%, the modulation magnification Sm is 75%, and the electrical angle Sφ is 60 degrees, the signal output unit 19 reads out the duty ratio of the PWM signal corresponding to the electrical angle Sφ=60 degrees from the basic modulation waveform table 170, determines the value obtained by multiplying the read-out duty ratio by the modulation magnification Sm (=0.75) as the duty ratio of the PWM signal to be generated, and outputs the PWM signal with the determined duty ratio as the drive control signal Sd.

[0087] When the modulation degree is changed to any one of 105% to 120%, the signal generating unit 16 generates a PWM signal in a similar manner. For example, when the modulation degree is 110%, the modulation magnification Sm is 98%, and the electrical angle Sφ is 90 degrees, the signal generating unit 16 reads out the duty ratio of the PWM signal corresponding to the electrical angle Sφ=90 degrees from the modulation waveform table 172 for the modulation degree of 110%, multiplies the read-out duty ratio by the modulation magnification Sm (=0.98), determines the value as the duty ratio of the PWM signal to be generated, and outputs the PWM signal with the determined duty ratio as the drive control signal Sd.

[0088] In addition, in the above explanation, an example was given of determining the duty ratio of the PWM signal to be generated by multiplying the duty ratio for each electrical angle Sφ read from the modulation waveform tables 170 to 174 by the modulation magnification Sm, but the method of determining the duty ratio based on the modulation magnification Sm is not limited to this.

[0089] For example, the signal generating section 16 may correct the modulation waveform tables 170 to 174 based on the modulation magnification Sm, and determine the duty ratio of the PWM signal to be generated in accordance with the corrected modulation waveform table.

[0090] Specifically, first, the modulation waveform table determination unit 18 multiplies the duty ratio for each electrical angle Sφ stored in the modulation waveform tables 170-174 by the modulation magnification Sm to generate new modulation waveform tables 170X-174X with corrected duty ratios. For example, when the modulation depth is 120% and the modulation magnification Sm is 96%, the modulation waveform table determination unit 18 generates the modulation waveform table 174 with a modulation depth of 120% using the above-mentioned method based on the basic modulation waveform table 170 and table difference information 174A with a modulation depth of 120%. The modulation waveform table determination unit 18 multiplies the duty ratio for each electrical angle Sφ stored in the modulation waveform table 174 by the modulation magnification Sm (0.96) to generate the new modulation waveform table 174X. Next, the signal output unit 19 reads out the duty ratio corresponding to the electrical angle Sφ from the modulation waveform tables 170X to 174X determined by the modulation waveform table determination unit 18, and generates a PWM signal of the read duty ratio.

[0091] This makes it possible to generate a PWM signal with an appropriate duty ratio according to the modulation degree and modulation magnification Sm, just as in the case where the duty ratio read out from the modulation waveform table is adjusted according to the modulation degree.

[0092] Next, the flow of processing related to the generation of a PWM signal by the control circuit 5 will be described.

[0093] FIG. 5 is a diagram showing an example of a processing flow relating to generation of a PWM signal. Here, it is assumed that the threshold value Sth of the modulation magnification Sm is set to 95%. Also, it is assumed that the modulation degree is set to a reference value (100%) as an initial state of the control circuit 5.

[0094] First, the deviation calculation unit 14 of the control circuit 5 calculates the deviation Sdf (=Stg-Sr) of the rotation speed Sr calculated by the rotation speed calculation unit 11 from the target rotation speed Stg analyzed by the drive command analysis unit 10 (step S1).

[0095] Next, the PWM signal generation unit 13 of the control circuit 5 determines whether the modulation ratio Sm is the maximum value (step S2). For example, first, the modulation ratio calculation unit 15 calculates the modulation ratio Sm by the above-described method based on the deviation Sdf calculated in step S1. Next, the modulation waveform table determination unit 18 determines whether the modulation ratio Sm calculated by the modulation ratio calculation unit 15 is a preset maximum value (for example, 100%).

[0096] When the modulation ratio Sm is the maximum value (step S2: YES), the modulation waveform table determination unit 18 determines whether the rotational speed Sr of the motor 3 has reached the target rotational speed Stg (step S3). For example, the modulation waveform table determination unit 18 determines whether the deviation Sdf is within a predetermined range (|Sdf| < r). Here, r is an arbitrary value of 0 or more set in advance.

[0097] When the deviation Sdf is within the predetermined range, that is, when the rotational speed Sr of the motor 3 has reached the target rotational speed Stg, the modulation waveform table determination unit 18 does not change the modulation waveform table, and the signal output unit 19 uses the modulation waveform table of the modulation degree set at that time (in the initial state, the basic modulation waveform table 170) to generate a PWM signal by the above-described method (step S8).

[0098] On the other hand, when the deviation Sdf is not within the predetermined range, that is, when the rotational speed Sr of the motor 3 has not reached the target rotational speed Stg, the modulation waveform table determination unit 18 increases the modulation degree by a predetermined amount α (for example, 5%) (step S4). For example, when the modulation degree is the reference value (100%), the modulation ratio Sm is 100%, and the rotational speed Sr has not reached the target rotational speed Stg, the modulation waveform table determination unit 18 changes the modulation degree from 100% to 105%.

[0099] Next, the modulation waveform table determination unit 18 updates the modulation waveform table based on the modulation degree determined in step S4 (step S7). For example, if the modulation degree is increased from 100% to 105% in step S4, the modulation waveform table determination unit 18 generates a modulation waveform table 171 with a modulation degree of 105% based on the basic modulation waveform table 170 and table difference information 171A using the method described above. Thereafter, the signal output unit 19 generates a PWM signal using the modulation waveform table generated in step S7 using the method described above (step S8).

[0100] If the modulation magnification Sm is not the maximum value in step S2 (step S2: NO), the modulation waveform table determination unit 18 determines whether the modulation magnification Sm is equal to or less than the threshold value Sth (95%) (step S5). If the modulation magnification Sm is not equal to or less than the threshold value Sth (step S5: NO), that is, if the modulation magnification Sm is greater than 95% and less than 100%, the modulation waveform table determination unit 18 does not change the modulation waveform table. In this case, the signal output unit 19 continues to generate a PWM signal by the above-described method using the set modulation waveform table (basic modulation waveform table 170 in the initial state) (step S8).

[0101] On the other hand, if the modulation magnification Sm is equal to or less than the threshold value Sth (step S5: YES), that is, if the modulation magnification Sm is smaller than 95%, the modulation waveform table determination unit 18 reduces the modulation degree by a predetermined amount β (for example, 5%) (step S6). For example, if the modulation degree is increased to the maximum value (120%) and then the modulation magnification Sm falls below the threshold value Sth (95%), the modulation waveform table determination unit 18 changes the modulation degree from 120% to 115%.

[0102] Next, the modulation waveform table determination unit 18 updates the modulation waveform table based on the modulation degree determined in step S6 (step S7). For example, as described above, when changing the modulation degree from 120% to 115% in step S6, the modulation waveform table determination unit 18 generates modulation waveform table 173 with a modulation degree of 115% based on basic modulation waveform table 170 and table difference information 173A using the method described above. Thereafter, the signal output unit 19 generates a PWM signal using the modulation waveform table generated in step S7 using the method described above (step S8).

[0103] The control circuit 5 updates the modulation waveform table and generates a PWM signal by repeatedly executing the above-mentioned process.

[0104] FIG. 6 is a diagram showing an example of changes in rotation speed Sr of motor 3 when the modulation degree of PWM control is changed in motor drive control device 2 according to the embodiment.

[0105] In FIG. 6, the horizontal axis represents the modulation degree [%], the vertical axis represents the rotation speed Sr [rpm] of the motor 3, and reference numeral 180 represents the characteristic of the maximum value of the rotation speed Sr relative to the modulation degree.

[0106] As shown in FIG. 6, in the motor drive control device 2 according to this embodiment, the rotation speed Sr can be increased by increasing the modulation degree in PWM control using the above-described method.

[0107] As described above, in the motor drive control device 2 according to this embodiment, when the rotation speed Sr of the motor 3 has not reached the target rotation speed Stg, the control circuit 5 increases the modulation degree in the PWM control to generate a drive control signal Sd as a PWM signal, thereby controlling the drive of the motor 3.

[0108] According to this, even if the rotation speed Sr of the motor 3 does not reach the target rotation speed Stg due to the load on the motor 3 or the like, by increasing the modulation degree in the PWM control, it is possible to more reliably bring the rotation speed Sr closer to the target rotation speed Stg.

[0109] Furthermore, as described above, when the modulation magnification Sm, which represents the manipulated variable for reducing the deviation Sdf of the rotation speed Sr from the target rotation speed Stg to zero in PWM control, is at its maximum value (e.g., 100%) and the rotation speed Sr has not reached the target rotation speed Stg, the control circuit 5 increases the modulation degree in PWM control in stages from a reference value (e.g., 100%). This makes it possible to accurately detect when the rotation speed Sr of the motor 3 has not reached the target rotation speed Stg, and then more quickly increase the rotation speed Sr of the motor 3 to bring it closer to the target rotation speed Stg.

[0110] Furthermore, the control circuit 5 may set the modulation degree to a value higher than the reference value (for example, 105% to 120%), and then, when the modulation magnification Sm is smaller than the maximum value (100%), reduce the modulation degree in stages to the reference value (100%). Specifically, as described above, after setting the modulation degree to a value higher than the reference value (for example, 105% to 120%), when the modulation magnification Sm is equal to or smaller than the threshold value Sth (for example, 95%), the control circuit 5 reduces the modulation degree in stages to the reference value (100%).

[0111] As described above, this makes it possible to suppress vibrations of the motor 3 after the rotation speed Sr of the motor 3 reaches the target rotation speed Stg. In other words, it is possible to improve the responsiveness of the rotation speed Sr of the motor 3 while suppressing a decrease in the stability of the operation of the motor 3.

[0112] Furthermore, in the motor drive control device 2 according to this embodiment, the PWM signal generating unit 13 of the control circuit 5 includes a basic modulation waveform table 170 that defines the duty ratio of the PWM signal for each electrical angle Sφ according to the modulation degree, and adjusts the duty ratio corresponding to the electrical angle Sφ determined based on the basic modulation waveform table 170 according to the modulation magnification Sm, and generates a PWM signal having the adjusted duty ratio.

[0113] According to this, the duty ratio of the PWM signal to be generated is determined using a modulation waveform table, so that complex calculations such as vector calculations are not required, and the calculation load on the processor constituting the control circuit 5 can be reduced.

[0114] Furthermore, when the modulation degree is changed, the PWM signal generating unit 13 generates a PWM signal using a modulation waveform table corresponding to the changed modulation degree. As a result, for example, as described above, by generating a modulation waveform table for each modulation degree or by preparing a modulation waveform table for each modulation degree, the duty ratio of the PWM signal can be easily determined without performing complex calculations even when the modulation degree is changed.

[0115] Furthermore, in the motor drive control device 2, the memory unit 17 of the control circuit 5 stores a basic modulation waveform table 170 when the modulation degree is a reference value (100%), and table difference information 171A to 174A including information on the difference in duty ratio for each electrical angle Sφ701 of the modulation waveform table corresponding to the changed modulation degree relative to the basic modulation waveform table 170, and the signal generation unit 16 generates modulation waveform tables 171 to 174 corresponding to the changed modulation degree based on the basic modulation waveform table 170 and the table difference information 171A to 174A.

[0116] This reduces the amount of data to be stored in advance in the storage unit 17 compared to when the modulation waveform tables 171 to 174 corresponding to modulation indices other than the reference value are stored in the storage unit 17. This reduces the storage capacity of the nonvolatile storage device that implements the storage unit 17, and makes it possible to reduce the cost of the control circuit 5.

[0117] In the above example, the modulation waveform tables 171 to 174 are generated based on the basic modulation waveform table 170 and the table difference information 171A to 174A. However, this is not limiting. If the nonvolatile storage device for implementing the storage unit 17 has sufficient storage capacity, multiple modulation waveform tables 171 to 174 with different modulation indices may be stored in advance in the storage unit 17 instead of the table difference information 171A to 174A.

[0118] In this case, when changing the modulation degree, the modulation waveform table determination unit 18 selects one modulation waveform table corresponding to the changed modulation degree from among the plurality of modulation waveform tables 171 to 174 stored in the storage unit 17. The signal output unit 19 generates a PWM signal using the selected modulation waveform table. This eliminates the need for calculations to generate the modulation waveform tables 171 to 174 after the modulation degree has been changed, and therefore the calculation load on the processor constituting the control circuit 5 can be further reduced.

[0119] <<Extension of Embodiment>> The invention made by the present inventors has been specifically described above based on an embodiment, but it goes without saying that the invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

[0120] For example, in the above embodiment, the predetermined amounts α and β, which are unit changes in modulation, are both 5%, but this is not limiting. The predetermined amounts α and β may be values ​​other than 5%, or α and β may be different values.

[0121] In the above embodiment, the motor 3 is not limited to a brushless DC motor. Also, the motor 3 is not limited to a three-phase motor, and may be, for example, a single-phase brushless DC motor.

[0122] In the above embodiment, a Hall element is used as the position detector 4, but this is not limiting. For example, a Hall IC, an encoder, a resolver, or the like may be provided as the position detector 4, and the detection signal thereof may be input as the position detection signal Sh to the motor drive control device 2. Furthermore, the motor drive control device 2 may calculate the rotational speed Sr and electrical angle Sφ of the motor 3 by calculation using a known position sensorless method, without providing the position detector 4.

[0123] Furthermore, although an example has been given in which each functional unit of the control circuit 5 is realized by program processing of the MCU, this is not limited to this, and some or all of the functional units of the control circuit 5 may be realized by a dedicated circuit (hardware).

[0124] Furthermore, the above-described flowcharts are merely examples and are not limited to these. For example, other processes may be inserted between each step, or the processes may be parallelized. [Explanation of symbols]

[0125] 1...motor unit, 2...motor drive control device, 3...motor, 4...position detector, 5...control circuit, 6...drive circuit, 10...drive command analysis unit, 11...rotational speed calculation unit, 12...electrical angle calculation unit, 13...PWM signal generation unit, 14...deviation calculation unit, 15...modulation magnification calculation unit, 16...signal generation unit, 17...storage unit, 18...modulation waveform table determination unit, 19...signal output unit, Sc...drive command signal (speed command signal), Stg...target rotational speed, Sr...rotational speed, Sdf...(speed) deviation, Sm...modulation magnification, Sth...modulation magnification threshold, Sd...drive control signal (PWM signal), Sφ...electrical angle, 170...basic modulation waveform table, 171 to 174...modulation waveform table, 171A to 174A...table difference information

Claims

1. a drive circuit that applies an AC voltage obtained by switching a DC voltage based on a drive control signal for controlling the drive of the motor to a coil of the motor; a control circuit that performs PWM control to generate a PWM signal as the drive control signal so that the rotation speed of the motor coincides with a target rotation speed and a sinusoidal current flows through the coil, the control circuit, when the rotation speed has not reached the target rotation speed, increases a modulation factor indicating a ratio of a command value of the AC voltage to the DC voltage to generate the PWM signal; the control circuit calculates a modulation magnification representing a manipulated variable for making a deviation of the rotation speed from the target rotation speed zero in the PWM control; the control circuit determines whether the modulation magnification is at a maximum value and whether the rotation speed has reached the target rotation speed; The control circuit increases the modulation factor in stages from a reference value when the modulation factor is at a maximum value and the rotation speed has not reached the target rotation speed. Motor drive control device.

2. 2. The motor drive control device according to claim 1, The control circuit sets the modulation degree to a value higher than the reference value, and then, when the modulation magnification is smaller than the maximum value, reduces the modulation degree to the reference value in a stepwise manner. Motor drive control device.

3. 3. The motor drive control device according to claim 1, The control circuit an electrical angle calculation unit that calculates an electrical angle of the motor; a PWM signal generating unit that includes a modulation waveform table that defines a duty ratio of the PWM signal for each electrical angle in accordance with the modulation degree, adjusts the duty ratio corresponding to the electrical angle determined based on the modulation waveform table in accordance with the modulation magnification, and generates the PWM signal having the adjusted duty ratio, When the modulation factor is changed, the PWM signal generating unit generates the PWM signal using the modulation waveform table corresponding to the changed modulation factor. Motor drive control device.

4. 4. The motor drive control device according to claim 3, The PWM signal generation unit a deviation calculation unit that calculates the deviation; a modulation magnification calculation unit that calculates the modulation magnification based on the deviation; a storage unit that stores a basic modulation waveform table, which is the modulation waveform table when the modulation index is the reference value, and information on the difference between the basic modulation waveform table and the modulation waveform table when the modulation index is a value different from the reference value; a signal generating unit that adjusts the duty ratio of the PWM signal for each electrical angle in the modulation waveform table based on the modulation magnification and generates the PWM signal having the adjusted duty ratio, When changing the modulation index to a value different from the reference value, the signal generating unit generates the modulation waveform table when the modulation index is a value different from the reference value based on the modulation waveform table when the modulation index is the reference value and information on the difference, which are stored in the storage unit. Motor drive control device.

5. 4. The motor drive control device according to claim 3, The PWM signal generation unit a deviation calculation unit that calculates the deviation; a modulation magnification calculation unit that calculates the modulation magnification based on the deviation; a storage unit that stores a plurality of modulation waveform tables each having a different modulation degree; a signal generating unit that adjusts the duty ratio of the PWM signal for each electrical angle in the modulation waveform table based on the modulation magnification and generates the PWM signal having the adjusted duty ratio, When changing the modulation factor, the signal generating unit selects the modulation waveform table corresponding to the changed modulation factor from among the plurality of modulation waveform tables stored in the storage unit, and generates the PWM signal. Motor drive control device.

6. The motor drive control device according to any one of claims 1 to 5; the motor; Motor unit.

7. a first step of performing PWM control to generate a PWM signal so that the rotation speed of the motor coincides with a target rotation speed and a sinusoidal current flows through a coil of the motor; a second step of applying an AC voltage obtained by switching a DC voltage based on the PWM signal generated in the first step to the coil; The first step is a third step of calculating a modulation magnification representing a manipulated variable for making a deviation of the rotation speed from the target rotation speed zero in the PWM control; a fourth step of determining whether the modulation magnification is a maximum value and whether the rotation speed has reached the target rotation speed; and a fifth step of generating the PWM signal by gradually increasing a modulation factor indicating a ratio of a command value of the AC voltage to the DC voltage when the modulation factor is a maximum value and the rotation speed has not reached the target rotation speed. Motor drive control method.

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