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

Abstract

To improve both stability and responsibility of a rotational speed of a motor in speed control of the motor.SOLUTION: A motor drive control apparatus 2 comprises: a drive circuit 6 that drives a motor 3 on the basis of a drive control signal Sd; and a control circuit 5 that, on the basis of a drive command signal Sc designating a target rotational speed, calculates an operation amount Md for the motor 3 so that the motor 3 rotates at the target rotational speed, and generates and outputs the drive control signal Sd corresponding to the operation amount Md. The control circuit 5, when decelerating the motor 3 due to a change of the target rotational speed, sets a rate of change Rv of the operation amount to be smaller as the operation amount Md approaches a target operation amount Mtg corresponding to the target rotational speed. The control circuit 5 changes the operation amount Md according to the rate of change Rv so that the operation amount Md coincides with the target operation amount Mtg after the change when decelerating the motor 3 due to the change of the target rotational speed.SELECTED DRAWING: Figure 2

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] A commonly known motor control method is speed control, which controls the motor so that it rotates at a target rotational speed (see, for example, Patent Document 1). In speed control, it is desirable for the motor's rotational speed to reach the target rotational speed in as short a time as possible. For example, when a motor is used as a drive source for a rotor (propeller) in a flying device such as a drone, it is necessary to change the target rotational speed when the flying device's body is to make a sharp turn, so that the motor's rotational speed quickly reaches the target rotational speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2846332 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have discovered that there are problems with a drive control method for a motor that rotates a propeller in a flying device such as a drone, as described below.

[0005] A motor drive control device for controlling the drive of a motor for a flight device calculates an operation amount corresponding to a target rotational speed, generates a PWM signal (drive control signal) with a duty ratio corresponding to the operation amount, and drives an inverter circuit to control the motor so that the motor (rotor) rotates at the target rotational speed. Here, the operation amount of the motor is the duty ratio of the PWM signal (drive control signal) for driving the inverter circuit, and is a value corresponding to the magnitude of the power (current) to be supplied to the motor. By changing the duty ratio, the motor (rotor) is controlled so that it rotates at the target rotational speed.

[0006] For example, when decelerating the body of a flying device, the motor drive control device reduces the duty ratio of the drive control signal by decreasing the manipulated variable at a predetermined rate to a target manipulated variable corresponding to the target rotational speed, thereby decreasing the rotational speed of the motor and decelerating the flying device.

[0007] However, during deceleration, the centrifugal force of the propeller connected to the motor increases the load on the motor, causing the motor's rotational speed to change more slowly in response to changes in the duty ratio of the drive control signal. As a result, it takes longer for the motor's rotational speed to reach the target rotational speed. In other words, the motor's speed responsiveness decreases during deceleration.

[0008] Therefore, the inventors of the present application have investigated increasing the rate of change of the motor operation amount (duty ratio of the drive control signal) when the flight device is decelerating, thereby improving the speed response of the motor.

[0009] However, if the rate of change of the manipulated variable when the motor is decelerating is increased, the duty ratio of the drive control signal is set to a value lower than the value appropriate for the motor's rotation speed at that time, which causes a large back electromotive force to be generated in the motor and an increase in the voltage (power supply voltage) of the power line connected to the inverter circuit that drives the motor.

[0010] FIG. 7 is a diagram showing the change over time in the power supply voltage during deceleration of a motor driven by a motor drive control method according to a prior study by the present inventors.

[0011] 7, the horizontal axis represents time (sec), and the vertical axis represents the voltage (power supply voltage) (V) of the power line connected to the inverter circuit that drives the motor. Reference numeral 800 represents the simulation results of the power supply voltage versus time when the rate of change of the motor's operation amount (duty ratio) is fixed at a large value and the motor is decelerated.

[0012] As shown in Figure 7, when the motor is driven normally with the power supply voltage set to 40V and then suddenly decelerated at 1 sec, it can be seen that the power supply voltage rises to around 65V. This phenomenon is thought to be caused by the sudden drop in the motor operation amount, i.e., the duty ratio of the drive control signal, during deceleration, which causes a large back electromotive force to be generated in the motor coil, and this back electromotive force is then regenerated in the power supply line.

[0013] In this way, if the rate of change of the motor's operation amount (duty ratio) when the motor is decelerating is simply increased, the power supply voltage will rise, making the motor drive control unstable and there is a risk of failure of the electronic components that make up the motor drive control device.

[0014] The present invention has been made to solve the above-mentioned problems, and has an object to improve the speed response of a motor while suppressing an increase in power supply voltage when the motor is decelerating. [Means for solving the problem]

[0015] A motor drive control device according to a representative embodiment of the present invention comprises a drive circuit that drives a motor based on a drive control signal for controlling drive of the motor, and a control circuit that calculates an operation amount of the motor based on a drive command signal that specifies a target rotational speed of the motor so that the motor rotates at the target rotational speed, and generates and outputs the drive control signal according to the operation amount, wherein when decelerating the motor by changing the target rotational speed, the control circuit sets a rate of change of the operation amount so that the rate of change of the operation amount becomes smaller as the operation amount approaches a target operation amount corresponding to the target rotational speed, and when decelerating the motor by changing the target rotational speed, the control circuit changes the operation amount according to the rate of change so that the operation amount matches the changed target operation amount. [Effects of the Invention]

[0016] According to one aspect of the present invention, when a motor is decelerating, it is possible to improve speed responsiveness while suppressing an increase in power supply voltage. [Brief explanation of the drawings]

[0017] [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] FIG. 2 is a diagram illustrating an example of a functional block configuration of a control circuit. [Figure 3] 1 is a diagram illustrating an overview of a method for controlling a motor operation amount by a motor drive control device according to an embodiment. [Figure 4] 5A and 5B are diagrams for explaining a method for setting a rate of change of an operation amount by the motor drive control device according to the embodiment. [Figure 5] 5 is a flowchart showing a process flow relating to a method for setting a rate of change of an operation amount, performed by the motor drive control device according to the embodiment. [Figure 6A] 10A and 10B are diagrams showing changes over time in rotation speed during deceleration of the motor in the motor unit according to the embodiment. [Figure 6B]10 is a diagram showing a change over time in power supply voltage when the motor in the motor unit according to the embodiment is decelerating. FIG. [Figure 7] FIG. 10 is a diagram showing the change over time in power supply voltage during deceleration of a motor when the motor is driven by a motor drive control method according to a prior study example conducted by the present inventors. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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.

[0019] [1] A motor drive control device (2) according to a representative embodiment of the present invention comprises a drive circuit (6) that drives a motor (3) based on a drive control signal (Sd) for controlling the drive of the motor, and a control circuit (5) that calculates an operation amount (Md) of the motor based on a drive command signal (Sc) that specifies a target rotational speed of the motor so that the motor rotates at the target rotational speed, and generates and outputs the drive control signal according to the operation amount, wherein when the target rotational speed is changed to decelerate the motor, the control circuit sets a rate of change (Rv) of the operation amount so that the rate of change becomes smaller as the operation amount approaches a target operation amount (Mtg) corresponding to the target rotational speed, and when the target rotational speed is changed to decelerate the motor, the control circuit changes the operation amount according to the rate of change so that the operation amount matches the changed target operation amount.

[0020] [2] In the motor drive control device described in [1] above, when the control circuit decelerates the motor by changing the target rotational speed, the control circuit may divide an operation amount adjustment range (Wm), which is the range from the operation amount before the target operation amount is changed to the target operation amount after the change, into a plurality of sections (S1 to S(n+1)), and assign different change rates to each of the sections so that the change rate becomes smaller as the section is closer to the target operation amount.

[0021] [3] In the motor drive control device described in [2] above, the control circuit may divide the manipulated variable adjustment range into the plurality of sections by equally dividing the manipulated variable adjustment range.

[0022] [4] In the motor drive control device described in [2] above, the control circuit may divide the manipulated variable adjustment range into the plurality of sections by dividing the manipulated variable adjustment range at different ratios.

[0023] [5] In the motor drive control device described in [2] above, the control circuit includes a target operation amount calculation unit (11) that calculates the target operation amount based on the drive command signal, an operation amount calculation unit (15) that calculates the operation amount by changing the operation amount according to the rate of change so that the operation amount reaches the target operation amount, a drive control signal generation unit (17) that generates a PWM signal having a duty ratio according to the operation amount and outputs it as the drive control signal, a deceleration determination unit (12) that, when the target operation amount is changed, determines whether or not to decelerate the motor based on the difference between the target operation amount and the operation amount, and, when the deceleration determination unit determines that the motor should be decelerated, The control system may include a reference point setting unit (13) that sets a reference point within a manipulated variable adjustment range, a storage unit (16) that stores change rate information (Gd1 to Gd(n+1)) including a plurality of different values that can be set as the change rate, and a change rate setting unit (14) that divides the manipulated variable adjustment range into a plurality of intervals with the reference point as a boundary and sets the change rate for each interval, wherein the change rate setting unit sets the change rate for each interval based on the change rate information so that the change rate becomes smaller as the interval approaches the target manipulated variable, and the manipulated variable calculation unit identifies the interval to which the immediately preceding manipulated variable belongs, and changes the manipulated variable to the target manipulated variable based on the change rate set for the identified interval.

[0024] [6] In the motor drive control device described in [5] above, the storage unit may store a reference point calculation condition (20) that specifies the ratio at which the operation amount adjustment range is divided, and the reference point setting unit may set the reference point to a point at which the operation amount adjustment range is divided at the ratio specified in the reference point calculation condition.

[0025] [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.

[0026] [8] A motor control method according to a representative embodiment of the present invention includes a first step of calculating an operation amount of the motor so that the motor rotates at a target rotational speed, and a second step of generating a drive control signal corresponding to the operation amount calculated in the first step and driving the motor, wherein the first step includes a third step (steps St1 to St8) of setting a rate of change of the operation amount so that the rate of change of the operation amount becomes smaller as the operation amount approaches a target operation amount corresponding to the target rotational speed when the motor is decelerated by changing the target rotational speed, and a fourth step of changing the operation amount based on the rate of change so that the operation amount matches the changed target operation amount when the motor is decelerated by changing the target rotational speed.

[0027] 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.

[0028] <Embodiment> FIG. 1 is a diagram showing the configuration of a motor unit 1 equipped with a motor drive control device 2 according to an embodiment. FIG. 2 is a diagram showing an example of a functional block configuration of the control circuit 5. As shown in FIG.

[0029] 1 is mounted on a flying device such as a drone and can be used as a drive source for the rotors (propellers) of the flying device. The motor unit 1 includes, for example, a motor 3 and a motor drive control device 2.

[0030] 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). For example, the rotor 4 is connected to the output shaft of the motor 3 via a reducer (not shown) or the like.

[0031] The motor unit 1 may include a position detection device such as a Hall element that detects the magnetic poles of the rotor (not shown) of the motor 3 and outputs a position detection signal whose voltage changes in accordance with the rotation of the rotor.

[0032] The motor drive control device 2 is a device that controls the driving of the motor 3. The motor drive control device 2 controls the driving of the motor 3 so that the motor 3 rotates at a target rotation speed specified by a drive command signal Sc, for example.

[0033] Specifically, the motor drive control device 2 includes a control circuit 5 and a drive circuit 6.

[0034] 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 (Pulse Width Modulation) signal.

[0035] The drive circuit 6 is, for example, an inverter circuit (for example, an H-bridge circuit) having a plurality of transistors as switching elements. The drive circuit 6 switches the connection destination of the coil of the motor 3 between a DC voltage and a ground potential in response to a PWM signal as the drive control signal Sd, thereby switching the direction of the motor current and rotating the motor 3.

[0036] 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 flowing through the motor may be connected to the inverter circuit.

[0037] 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 connected to each other via a bus or dedicated lines. For example, the control circuit 5 is a microcontroller (MCU: Micro Controller Unit).

[0038] The control circuit 5 and the drive circuit 6 may be configured as a single semiconductor integrated circuit (IC: Integrated Circuit) packaged together, or may be packaged as separate integrated circuits mounted on a circuit board and electrically connected to each other on the circuit board.

[0039] The control circuit 5 has a function of calculating an operation amount Md of the motor 3 so that the motor 3 rotates at the target rotation speed based on a drive command signal Sc that specifies a target rotation speed of the motor 3, and generating and outputting a drive control signal Sd corresponding to the operation amount Md. Specifically, the control circuit 5 calculates an operation amount Mtg of the motor 3 corresponding to the target rotation speed (hereinafter also referred to as the "target operation amount") using, for example, open-loop control, and generates a PWM signal with a duty ratio corresponding to the target operation amount Mtg and outputs it as the drive control signal Sd, thereby rotating the motor 3 at the target rotation speed. Furthermore, when decelerating the motor 3 by changing the target rotation speed, the control circuit 5 changes the operation amount Md so that the operation amount Md matches the target operation amount Mtg corresponding to the changed target rotation speed.

[0040] Furthermore, the control circuit 5 has a function of switching the rate of change Rv of the manipulated variable of the motor 3 when decelerating the motor 3. Here, the rate of change Rv of the manipulated variable is the amount of change in the manipulated variable per unit time or per unit control period, and is, for example, the amount of change in the duty ratio per period (PWM period) of the PWM signal serving as the drive control signal Sd. The following will explain an outline of a method for switching the rate of change Rv of the manipulated variable by the control circuit 5, with reference to the drawings.

[0041] FIG. 3 is a diagram for explaining a method for controlling the operation amount of the motor 3 by the motor drive control device 2 according to the embodiment.

[0042] 3, the vertical axis represents the manipulated variable Md of the motor 3, and the horizontal axis represents time t. Reference numeral 300 represents a graph of the manipulated variable Md versus time when the manipulated variable Md is changed by the motor drive control method according to this embodiment, and reference numerals 301 and 302 represent graphs of the manipulated variable Md versus time when the manipulated variable Md is changed at a constant rate of change as a comparative example of the motor drive control method according to this embodiment.

[0043] When decelerating the motor 3 by changing the target rotation speed, the control circuit 5 sets the rate of change Rv of the manipulated variable Md to decrease as the manipulated variable Md approaches the target manipulated variable Mtg. More specifically, when decelerating the motor 3 by changing the target rotation speed, the control circuit 5 divides the manipulated variable adjustment range Wm, which ranges from the manipulated variable Md(0) before the target manipulated variable Mtg is changed to the changed target manipulated variable Mtg, into a plurality of sections S1 to S(n+1) (n is an integer equal to or greater than 1), and assigns different rates of change Rv to each of the sections S1 to S(n+1) so that the rate of change Rv decreases as the sections S1 to S(n+1) are closer to the target manipulated variable Mtg.

[0044] For example, as shown in FIG. 3, consider a case where the manipulated variable Md is changed from the manipulated variable Md(0) before the target manipulated variable Mtg is changed to the changed target manipulated variable Mtg in order to decelerate the motor 3.

[0045] In this case, first, the control circuit 5 divides the manipulated variable adjustment range Wm from the manipulated variable Md(0) to the target manipulated variable Mtg into a plurality of sections S1 to S(n+1). Fig. 3 shows an example in which the manipulated variable adjustment range Wm is divided into two sections S1 and S2 with reference to a reference point Mth1.

[0046] Next, the control circuit 5 assigns different change rates Rv to each of the sections S1 and S2 so that the change rates Rv (the rate of change of the manipulated variable over time) become smaller for the sections S1 and S2 closer to the target manipulated variable Mtg. For example, if Gd1>Gd2, the control circuit 5 sets "Gd1" as the change rate Rv for the section S1 from the pre-change manipulated variable Md(0) to the reference point Mth1, and sets "Gd2" as the change rate Rv for the section S2 from the reference point Mth1 to the changed target manipulated variable Mtg.

[0047] The control circuit 5 then changes the manipulated variable Md according to the rate of change Rv so that the manipulated variable Md coincides with the target manipulated variable Mtg corresponding to the changed target rotation speed. For example, as shown in Fig. 3, the control circuit 5 changes the manipulated variable Md from the manipulated variable Md(0) before the target manipulated variable Mtg was changed to the changed target manipulated variable Mtg, following the graph indicated by reference numeral 300. The specific configuration of the control circuit 5 for realizing the above functions will be described in detail below.

[0048] As shown in FIG. 2, the control circuit 5 has, as functional blocks for realizing the above-mentioned functions, for example, a target operation amount calculation unit 11, a deceleration determination unit 12, a reference point setting unit 13, a change rate setting unit 14, an operation amount calculation unit 15, a memory unit 16, and a drive control signal generation unit 17.

[0049] Each of the above-described functional units of the control circuit 5 is realized, for example, by program processing of an MCU serving as the control circuit 5. Specifically, each of the above-described functional units is realized by a processor constituting the MCU serving as the control circuit 5 performing various calculations in accordance with a program stored in a memory to control each of the peripheral circuits constituting the MCU.

[0050] The target operation amount calculation unit 11 is a functional unit that calculates the target operation amount Mtg based on the drive command signal Sc. Here, the drive command signal Sc is a signal that includes information that indicates a target operating state of the motor 3, such as a signal that includes information that specifies a target rotation speed of the motor 3. The drive command signal Sc may be, for example, a serial signal or a PWM signal that has a duty ratio that corresponds to the target rotation speed.

[0051] The target operation amount calculation unit 11 acquires information on the target rotation speed included in the drive command signal Sc when the drive command signal Sc is input to the control circuit 5. The target operation amount calculation unit 11 calculates a target operation amount Mtg, which is the operation amount of the motor 3 corresponding to the target rotation speed.

[0052] For example, correspondence information such as a table or function indicating the correspondence between the target rotation speed and the target manipulated variable Mtg is stored in advance in the storage unit 16. The target manipulated variable Mtg and the manipulated variable Md may be values indicating the duty ratio of the PWM signal serving as the drive control signal Sd. For example, the target manipulated variable Mtg is set to increase as the target rotation speed increases. Therefore, the duty ratio of the drive control signal Sd increases as the target rotation speed increases.

[0053] The target operation amount calculation unit 11 calculates the target operation amount Mtg corresponding to the target rotation speed obtained from the drive command signal Sc by referring to the correspondence relationship information stored in the storage unit 16. The target operation amount Mtg is stored in the storage unit 16.

[0054] The storage unit 16 is a functional unit that stores various data necessary for the control circuit 5 to realize the above functions. In addition to the target manipulated variable Mtg and correspondence relationship information indicating the correspondence relationship between the target rotation speed and the target manipulated variable Mtg described above, the storage unit 16 also stores, for example, the manipulated variable Md, the rate of change Rv, a plurality of different values Gd1 to Gd(n+1) that can be set as the rate of change Rv, a reference point calculation condition 20, and reference points Mth1 to Mth(n), which will be described later.

[0055] The operation amount calculation unit 15 is a functional unit that calculates the operation amount Md of the motor 3. The operation amount calculation unit 15 calculates and outputs the operation amount Md so that the operation amount Md matches the target operation amount Mtg, and stores it in the storage unit 16. Specifically, as shown in FIG. 3, the operation amount calculation unit 15 changes the operation amount Md to the target operation amount Mtg according to the change rate Rv set for each of the intervals S1 to S(n+1) from the operation amount Md(0) before the target operation amount Mtg is changed to the target operation amount Mtg after the change.

[0056] The drive control signal generation unit 17 is a functional unit that generates a drive control signal Sd. The drive control signal generation unit 17 generates a PWM signal having a duty ratio corresponding to the operation amount Md calculated by the operation amount calculation unit 15, and outputs it as the drive control signal Sd. For example, when the operation amount Md represents a duty ratio, the drive control signal generation unit 17 outputs a PWM signal having the duty ratio specified by the operation amount Md as the drive control signal Sd.

[0057] The deceleration determination unit 12 is a functional unit that determines whether to decelerate the rotational speed of the motor 3. The deceleration determination unit 12 determines whether to decelerate the motor 3 based on the difference between the target operation amount Mtg and the operation amount Md when the target operation amount Mtg is changed. For example, when the value obtained by subtracting the operation amount Md from the target operation amount Mtg (Mtg - Md) is negative (Mtg < Md), the deceleration determination unit 12 determines to decelerate the motor 3. On the other hand, when the value obtained by subtracting the operation amount Md from the target operation amount Mtg (Mtg - Md) is positive (Mtg > Md), the deceleration determination unit 12 determines to accelerate the motor 3. Also, when the target operation amount Mtg and the operation amount Md are equal (Mtg = Md), the deceleration determination unit 12 determines not to decelerate the motor 3.

[0058] The reference point setting unit 13 is a functional unit that sets reference points Mth1 to Mth(n) that serve as references for switching the rate of change Rv within the manipulated variable adjustment range Wm when the deceleration determination unit 12 determines that the motor 3 should be decelerated. The rate of change setting unit 14 is a functional unit that divides the manipulated variable adjustment range Wm into a plurality of sections S1 to S(n+1) with the reference points Mth1 to Mth(n) as boundaries, and sets the rate of change Rv for each of the sections S1 to S(n+1).

[0059] FIG. 4 is a diagram for explaining a method for setting the rate of change Rv of the manipulated variable by the motor drive control device 2 according to the embodiment.

[0060] When the deceleration determination unit 12 determines that the motor 3 is to be decelerated due to a change in the target manipulated variable Mtg, the reference point setting unit 13 acquires the manipulated variable Md(0) before the target manipulated variable Mtg was changed and the target manipulated variable Mtg after the change from the storage unit 16. The reference point setting unit 13 calculates the manipulated variable adjustment range Wm based on the acquired manipulated variable Md(0) and target manipulated variable Mtg. For example, the reference point setting unit 13 determines the difference between the manipulated variable Md(0) and the target manipulated variable Mtg as the manipulated variable adjustment range Wm.

[0061] Next, the reference point setting unit 13 determines the reference points Mth1 to Mth(n) based on the reference point calculation conditions 20 stored in the storage unit 16. Here, the reference point calculation conditions 20 are information specifying the ratio by which the manipulated variable adjustment range Wm is divided, and are stored in advance in the storage unit 16. Note that the reference point calculation conditions 20 may be rewritable by a device external to the motor drive control device 2.

[0062] The reference point setting unit 13 sets the points that divide the manipulated variable adjustment range Wm at a ratio specified in the reference point calculation condition 20 as reference points Mth1 to Mth(n). For example, when the reference point calculation condition 20 that specifies dividing the manipulated variable adjustment range Wm into (n+1) equal parts is set in the storage unit 16 as shown in FIG. 4, the reference point setting unit 13 sets reference points Mth1 to Mth(n) for each small range obtained by dividing the manipulated variable adjustment range Wm by (n+1). That is, the value obtained by adding the value obtained by dividing the manipulated variable adjustment range Wm by (n+1) to the manipulated variable Md(0) is set as the reference point Mth1, and the value obtained by dividing the manipulated variable adjustment range Wm by (n+1) and multiplying it by "n" (Wm×n / (n+1)) is set as the reference point Mth(n).

[0063] For example, when the manipulated variable adjustment range Wm is divided into two (n=1), the reference point Mth1 is set to the value obtained by dividing the manipulated variable adjustment range Wm by 2 and adding the resultant value to the manipulated variable Md(0). As a result, one reference point Mth1 is set within the manipulated variable adjustment range Wm, and the manipulated variable adjustment range Wm is divided into two sections S1 and S2, with the reference point Mth1 as the boundary. Furthermore, when the manipulated variable adjustment range Wm is divided into three (n=2), the reference point Mth1 is set to the value obtained by adding the resultant value obtained by dividing the manipulated variable adjustment range Wm by 3 to the manipulated variable Md(0), and the reference point Mth2 is set to the value obtained by adding the resultant value obtained by dividing the manipulated variable adjustment range Wm by 3 and doubling it to the manipulated variable Md(0). As a result, two reference points Mth1 and Mth2 are set within the manipulated variable adjustment range Wm, and the manipulated variable adjustment range Wm is divided into three sections S1, S2, and S3 with the reference points Mth1 and Mth2 as boundaries.

[0064] In the following description, when there is no need to distinguish between the reference points Mth1 to Mth(n), they are also collectively referred to as "reference point Mth."

[0065] Here, the method for setting the sections S1 to S(n+1) is not limited to the method of equally dividing the manipulated variable adjustment range Wm described above. For example, the manipulated variable adjustment range Wm may be divided into a plurality of sections S1 to S(n+1) by dividing the manipulated variable adjustment range Wm at different ratios. For example, as shown in FIG. 3, when the reference point calculation condition 20 for specifying to divide the operation amount adjustment range Wm into two parts with a ratio of 2 to 1 based on the operation amount Md(0) is set in the storage unit 16, the reference point setting unit 13 may divide the operation amount adjustment range Wm into two intervals S1 and S2 by setting the reference point Mth1 to the value obtained by adding the value obtained by multiplying the operation amount adjustment range Wm by "2 / 3" to the operation amount Md(0). Alternatively, when the reference point calculation condition 20 for specifying to divide the operation amount Md(0) into two parts with a ratio of 1 to 2 is set in the storage unit 16, the reference point setting unit 13 may divide the operation amount adjustment range Wm into two intervals S1 and S2 by setting the reference point Mth1 to the value obtained by adding the value obtained by multiplying the operation amount adjustment range Wm by "1 / 3" to the operation amount Md(0).

[0066] The change rate setting unit 14 sets the change rate Rv for each of the intervals S1 to Sn such that the closer the interval S1 to Sn is to the target operation amount Mtg, the smaller the change rate Rv becomes, based on a plurality of different values Gd1 to Gd(n + 1) that can be set as the change rate Rv and are stored in the storage unit 16. For example, when Gd(n + 1) < Gd(n) <... < Gd2 < Gd1, the change rate setting unit 14 sets the change rate Rv of the interval S1 to "Gd1", sets the change rate Rv of the interval S2 to "Gd2", sets the change rate Rv of the interval S(n) to "Gd(n)", and sets the change rate Rv of the interval S(n + 1) to "Gd(n + 1)". For example, in the example of FIG. 3, the change rate setting unit 14 sets the change rate Rv of the interval S1 to "Gd1" and sets the change rate Rv of the interval S2 to "Gd2" which is smaller than "Gd1".

[0067] The operation amount calculation unit 15 identifies the interval S1 to Sn to which the immediately preceding operation amount Md belongs, and changes the operation amount Md to the target operation amount Mtg based on the rate of change Rv set for the identified interval S1 to Sn. In the example of Fig. 3, when the operation amount Md is in interval S1, the operation amount calculation unit 15 reduces the operation amount Md at the rate of change Rv=Gd1, and when the operation amount Md is in interval S2, the operation amount calculation unit 15 reduces the operation amount Md at the rate of change Rv=Gd2 which is smaller than the rate of change Rv=Gd1. Then, when the operation amount Md reaches the target operation amount Mtg, the operation amount calculation unit 15 fixes the operation amount Md to the target operation amount Mtg until the target operation amount Mtg is changed.

[0068] When the deceleration determination unit 12 determines that the motor 3 is to be accelerated due to a change in the target manipulated variable Mtg, the change rate setting unit 14 sets the change rate Rv to "Gu" based on, for example, the value Gu stored in the storage unit 16. That is, when the motor 3 is accelerating, the change rate Rv becomes a constant value (=Gu).

[0069] Next, a flow of a method for setting the rate of change Rv of the manipulated variable by the motor drive control device 2 according to the embodiment will be described.

[0070] 5 is a flowchart showing the flow of processing related to a method for setting the rate of change Rv of the manipulated variable by the motor drive control device 2 according to the embodiment. In the following description, as an example, it is assumed that one reference point Mth1 is set within the manipulated variable adjustment range Wm, and the manipulated variable adjustment range Wm is divided into two sections S1 and S2, as shown in FIG.

[0071] First, in the motor drive control device 2, the control circuit 5 acquires the value of the manipulated variable Md at that time and stores it in the memory unit 16 (step St1). Furthermore, the target manipulated variable calculation unit 11 of the control circuit 5 calculates the value of the target manipulated variable Mtg corresponding to the target rotation speed specified by the drive command signal Sc using the method described above and stores it in the memory unit 16 (step St2).

[0072] Next, the deceleration determination unit 12 of the control circuit 5 determines whether or not to decelerate the motor 3 (step St3). Specifically, the deceleration determination unit 12 determines whether or not to decelerate the motor 3 using the method described above, based on the value of the manipulated variable Md acquired in step St1 and the value of the target manipulated variable Mtg acquired in step St2. If the motor 3 is not to be decelerated or is to be accelerated (step St3: NO), the change rate setting unit 14 fixes the change rate Rv to "Gu" (step St9).

[0073] On the other hand, when the motor 3 is to be decelerated (step St3: YES), the control circuit 5 determines whether the target manipulated variable Mtg has been changed (step St4). When the target manipulated variable Mtg has been changed (step St4: YES), the reference point setting unit 13 sets the reference point Mth1 within the manipulated variable adjustment range Wm by the above-described method (step St5).

[0074] After the reference point Mth1 is set, or if there is no change in the target operation amount Mtg in step St4, the operation amount calculation unit 15 identifies the sections S1 and S2 to which the operation amount Md acquired in step St1 belongs (step St6). Specifically, the operation amount calculation unit 15 determines whether the operation amount Md is equal to or less than the reference point Mth1.

[0075] If the operation amount Md is equal to or greater than the reference point Mth1 (step St6: YES), the operation amount Md is in the section S1, and therefore the change rate setting unit 14 sets the change rate Rv to "Gd1" (step St7). On the other hand, if the operation amount Md is smaller than the reference point Mth1 (step St6: NO), the operation amount Md is in the section S2, and therefore the change rate setting unit 14 sets the change rate Rv to "Gd2" (step St8). Through the above processing procedure, the control circuit 5 sets the rate of change Rv of the operation amount of the motor 3.

[0076] Next, the effects of the motor drive control device 2 according to the embodiment will be described.

[0077] FIG. 6A is a diagram showing the change over time in the rotation speed of the motor 3 in the motor unit 1 according to the embodiment when the motor 3 is decelerated. FIG. 6B is a diagram showing the change over time in the power supply voltage when the motor 3 in the motor unit 1 according to the embodiment is decelerating.

[0078] In Fig. 6A, the horizontal axis represents time (sec), and the vertical axis represents the rotational speed (rpm) of the motor 3. Fig. 6A shows the simulation results of the change in rotational speed over time when the motor 3 rotating at 5000 rpm is decelerated to 1200 rpm. Specifically, reference numeral 600 represents the simulation results of the rotational speed of the motor 3 over time when the motor 3 is decelerated in the motor drive control device 2 according to embodiment 1, where the manipulated variable adjustment range Wm is divided into two sections as shown in Fig. 3 and the rate of change Rv of the manipulated variable is gradually reduced. Reference numeral 601 represents the simulation results of the rotational speed of the motor 3 over time when the motor 3 is decelerated in the motor drive control device 2 according to embodiment 1, where the rate of change Rv of the manipulated variable is fixed to a large value (>Gd1) (Rv = constant), as a comparative example.

[0079] In Figure 6B, the horizontal axis represents time (sec) and the vertical axis represents voltage (V). Figure 6B shows simulation results of the change over time in the voltage (power supply voltage) of the power supply line supplying power to the drive circuit 6 (inverter circuit) when the motor 3 rotating at 5000 rpm is decelerated to 1200 rpm. Specifically, reference numeral 700 represents the simulation results of the power supply voltage versus time when the motor 3 is decelerated in the motor drive control device 2 according to the first embodiment, where the manipulated variable adjustment range Wm is divided into two sections as shown in Figure 3 and the rate of change Rv of the manipulated variable is gradually reduced. Reference numeral 701 represents the simulation results of the power supply voltage versus time when the motor 3 is decelerated, as a comparative example, when the rate of change Rv of the manipulated variable of the motor 3 is fixed to a large value (>Gd1) (Rv = constant).

[0080] As can be seen from reference numerals 601 and 701, when the motor is decelerated while the rate of change Rv of the motor's manipulated variable is fixed at a large value, the speed at which the motor's rotational speed approaches the target rotational speed increases, but the power supply voltage also increases significantly. This causes the operation of the motor drive control device to become unstable, and as a result, it takes time for the rotational speed to reach the target rotational speed. Furthermore, since a large increase in power supply voltage raises concerns about damage to electronic components, it is necessary to select electronic components with high voltage resistance.

[0081] On the other hand, as can be seen from reference numerals 600 and 700, if the manipulated variable adjustment range Wm is divided into two sections and the rate of change Rv of the manipulated variable is reduced in stages, the increase in power supply voltage is suppressed. This stabilizes the operation of the motor drive control device, and as a result, the time it takes for the rotation speed to reach the target rotation speed is approximately the same as the time required to decelerate the motor with the rate of change Rv of the motor's manipulated variable fixed at a large value.

[0082] In this way, according to the motor drive control device 2 of the embodiment, when decelerating the motor 3, the rate of change Rv of the operation amount of the motor 3 is set to become smaller as the operation amount Md approaches the target operation amount Mtg, so that it is possible to improve speed responsiveness while suppressing an increase in power supply voltage when the motor is decelerating.

[0083] Furthermore, in the motor drive control device 2, when decelerating the motor 3 by changing the target rotational speed, the control circuit 5 divides the manipulated variable adjustment range Wm, which extends from the manipulated variable Md(0) before the target manipulated variable Mtg is changed to the changed target manipulated variable Mtg, into multiple sections S1 to S(n+1), and assigns a different rate of change Rv to each of the sections S1 to S(n+1) so that the rate of change Rv decreases as the section S1 to S(n+1) is closer to the target manipulated variable Mtg. In this way, the manipulated variable adjustment range Wm is divided into appropriate sections S1 to S(n+1) depending on the operating state of the motor 3 when deceleration operation is initiated, and a rate of change Rv is assigned to each section S1 to S(n+1), thereby enabling more stable deceleration operation of the motor.

[0084] Furthermore, in the motor drive control device 2, the control circuit 5 may equally divide the manipulated variable adjustment range Wm into a plurality of sections S1 to S(n+1). For example, as in the above example, the manipulated variable adjustment range Wm may be equally divided into two sections S1 and S2, or the manipulated variable adjustment range Wm may be equally divided into three sections S1, S2, and S3. This simplifies the calculations for setting the sections S1 to S(n+1), thereby reducing the computational load on the processor.

[0085] Furthermore, in the motor drive control device 2, the control circuit 5 may divide the manipulated variable adjustment range Wm into multiple sections S1 to S(n+1) by dividing the range Wm at different ratios (see FIG. 3). By appropriately setting the ratios, it is possible to improve speed responsiveness while effectively suppressing increases in power supply voltage.

[0086] Furthermore, in the motor drive control device 2, when it is determined that the motor 3 should be decelerated, the control circuit 5 sets a reference point Mth within the manipulated variable adjustment range Wm and divides the manipulated variable adjustment range Wm into a plurality of sections S1 to S(n+1) with the reference point Mth as the boundary. This makes it easy to divide the manipulated variable adjustment range Wm into appropriate sections S1 to S(n+1) depending on the operating state of the motor 3 when a deceleration operation is performed.

[0087] Furthermore, in the motor drive control device 2, the control circuit 5 sets the reference point Mth as a point that divides the manipulated variable adjustment range Wm at a ratio specified in the reference point calculation condition 20. This makes it easy to calculate the reference point Mth. Furthermore, by appropriately changing the reference point calculation condition 20, it is possible to set the reference point Mth at any position.

[0088] <<Extension of Embodiment>> The invention made by the inventor 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.

[0089] For example, in the above embodiment, the motor 3 is not limited to a three-phase brushless DC motor, but may be, for example, a single-phase brushless DC motor.Furthermore, the motor 3 is not limited to a brushless DC motor, but may be another type of motor.

[0090] 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).

[0091] 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]

[0092] 1...motor unit, 2...motor drive control device, 3...motor, 4...rotor (propeller), 5...control circuit, 6...drive circuit, 11...target manipulated variable calculation unit, 12...deceleration determination unit, 13...reference point setting unit, 14...change rate setting unit, 15...manipulated variable calculation unit, 16...memory unit, 17...drive control signal generation unit, 20...reference point calculation condition, Md...manipulated variable, Mtg...target manipulated variable, Mth, Mth1 to Mth(n)...reference point, Rv...change rate, S1 to S(n+1)...section, Sc...drive command signal (speed command signal), Sd...drive control signal, Wm...manipulated variable adjustment range, Md(0)...manipulated variable before target manipulated variable is changed (manipulated variable at start of acceleration / deceleration), Gd1 to Gd(n+1)...values that can be set as change rate.

Claims

1. a drive circuit that drives the motor based on a drive control signal for controlling the drive of the motor; a control circuit that calculates an operation amount of the motor based on a drive command signal that specifies a target rotation speed of the motor so that the motor rotates at the target rotation speed, and generates and outputs the drive control signal according to the operation amount, when the control circuit decelerates the motor by changing the target rotation speed, the control circuit sets a rate of change of the manipulated variable so that the rate of change of the manipulated variable becomes smaller as the manipulated variable approaches the target manipulated variable corresponding to the target rotation speed; When the target rotation speed is changed to decelerate the motor, the control circuit changes the manipulated variable according to the rate of change so that the manipulated variable coincides with the changed target manipulated variable. Motor drive control device.

2. 2. The motor drive control device according to claim 1, When the control circuit decelerates the motor by changing the target rotation speed, the control circuit divides an operation amount adjustment range, which is a range from the operation amount before the target operation amount is changed to the target operation amount after the change, into a plurality of sections, and assigns different change rates to each of the sections so that the change rate becomes smaller as the section becomes closer to the target operation amount. Motor drive control device.

3. 3. The motor drive control device according to claim 2, The control circuit divides the manipulated variable adjustment range into the plurality of sections by equally dividing the manipulated variable adjustment range. Motor drive control device.

4. 3. The motor drive control device according to claim 2, The control circuit divides the manipulated variable adjustment range into the plurality of sections by dividing the manipulated variable adjustment range at different ratios. Motor drive control device.

5. 3. The motor drive control device according to claim 2, The control circuit a target operation amount calculation unit that calculates the target operation amount based on the drive command signal; an operation amount calculation unit that calculates the operation amount by changing the operation amount according to the change rate so that the operation amount reaches the target operation amount; a drive control signal generating unit that generates a PWM signal having a duty ratio according to the manipulated variable and outputs the PWM signal as the drive control signal; a deceleration determination unit that determines whether to decelerate the motor based on a difference between the target manipulated variable and the manipulated variable when the target manipulated variable is changed; a reference point setting unit that sets a reference point within the manipulated variable adjustment range when the deceleration determination unit determines that the motor is to be decelerated; a storage unit that stores change rate information including a plurality of different values that can be set as the change rate; a change rate setting unit that divides the manipulated variable adjustment range into a plurality of sections with the reference point as a boundary and sets the change rate for each section, the change rate setting unit sets the change rate for each section based on the change rate information so that the change rate becomes smaller as the section becomes closer to the target manipulated variable; The operation amount calculation unit specifies the section to which the immediately preceding operation amount belongs, and changes the operation amount to the target operation amount based on the change rate set for the specified section. Motor drive control device.

6. 6. The motor drive control device according to claim 5, the storage unit stores a reference point calculation condition that specifies a ratio by which the manipulated variable adjustment range is divided; The reference point setting unit sets a point that divides the manipulated variable adjustment range at a ratio specified by the reference point calculation condition as the reference point. Motor drive control device.

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

8. a first step of calculating an operation amount of the motor so that the motor rotates at a target rotation speed; a second step of generating a drive control signal according to the operation amount calculated in the first step and driving the motor; The first step comprises: a third step of setting a rate of change of the manipulated variable so that the rate of change of the manipulated variable becomes smaller as the manipulated variable approaches a target manipulated variable corresponding to the target rotation speed when the motor is decelerated by changing the target rotation speed; and a fourth step of changing the manipulated variable based on the rate of change so that the manipulated variable coincides with the changed target manipulated variable when the motor is decelerated by changing the target rotation speed. Motor drive control method.

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