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

Abstract

The invention relates to a motor drive control device, a fan unit and a motor drive control method. The motor drive control device is characterized by comprising: a control circuit for generating a drive control signal for controlling the rotation of a motor; and a drive circuit that drives the motor on the basis of the drive control signal, the control circuit having: a drive control signal generation unit that generates the drive control signal such that the motor rotates at a target rotational speed which is a target value of the rotational speed of the motor; a current measuring unit that measures the current of the motor; a storage unit that stores current-related thresholds associated with each of the target rotational speeds; and an abnormality determination unit that determines whether or not the motor is abnormal on the basis of a result of comparison between the measured value of the current and a threshold value related to the current and corresponding to the target rotational speed.

Description

Technical Field

[0001] This invention relates to a motor drive control device, a fan unit, and a motor drive control method, for example, to a motor drive control device for controlling the rotation of a motor within a fan unit. Background Technology

[0002] Traditionally, fans (fan motors) have been widely known as cooling devices that dissipate heat generated inside electrical equipment to the outside, thereby cooling the interior of the equipment. A fan has a motor and an impeller connected to the motor's output shaft. The impeller rotates according to the rotation of the motor's output shaft, thereby generating airflow (wind). A fan, for example, together with a motor drive control device for controlling the motor of the fan, constitutes a fan unit. In the fan unit, the motor drive control device drives the motor according to instructions from a higher-level device, thereby causing the fan (motor) to rotate in one direction at a constant speed.

[0003] In recent years, motor drive control devices that not only drive motors (fans) but also detect motor malfunctions have been increasing. For example, Patent Document 1 discloses a technique for determining the lifespan of a motor by monitoring its rotational speed (revolutions).

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2021-19398 Summary of the Invention

[0005] The problem that the invention aims to solve The method of monitoring motor speed and detecting a decrease in speed to determine signs of motor life, as described in Patent Document 1, can determine signs of motor life when the motor speed is controlled in an open-loop manner. However, it cannot determine signs of motor life when the motor speed is controlled in a closed-loop manner (in the case of feedback control) with a constant motor speed. Especially in fan units, it is not easy to determine the signs of fan life caused by bearing deterioration when the motor (fan) becomes difficult to rotate due to years of deterioration of the bearings connected to the motor's output shaft.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to be able to properly detect the signs of motor life.

[0007] Solution for solving the problem A representative embodiment of the motor drive control device of the present invention is characterized by comprising: a control circuit for generating a drive control signal for controlling the rotation of a motor; and a drive circuit for driving the motor based on the drive control signal. The control circuit includes: a drive control signal generation unit for generating the drive control signal such that the motor rotates at a target speed, wherein the target speed is a target value of the motor's rotational speed; a current measurement unit for measuring the current of the motor; a storage unit for storing current-related thresholds established for each target speed; and an anomaly determination unit for determining whether the motor is abnormal based on a comparison result between the measured current value and the current-related threshold corresponding to the target speed.

[0008] Invention Effects According to the motor drive control device of the present invention, signs of motor life can be appropriately detected. Attached Figure Description

[0009] Figure 1 This is a block diagram illustrating the configuration of the fan unit in the implementation method.

[0010] Figure 2 This is a perspective view schematically showing the appearance of the fan unit in an embodiment.

[0011] Figure 3 It is a schematic representation. Figure 2 A cross-sectional view of the fan unit shown.

[0012] Figure 4 This is a graph illustrating an example of the relationship between a motor's speed and its rated current.

[0013] Figure 5A This is a graph illustrating an example of how the current in a motor changes over time.

[0014] Figure 5B This is a graph illustrating an example of how the current in a motor changes over time.

[0015] Figure 6 This is a flowchart illustrating an example of the process for determining and handling abnormal states in a motor drive control device according to an implementation method. Detailed Implementation

[0016] 1. Overview of the implementation method First, a summary of representative embodiments of the invention disclosed in this application will be given. It should be noted that, as an example, in the following description, reference numerals on the accompanying drawings corresponding to the constituent elements of the invention are indicated by parentheses.

[0017] [1] A motor drive control device (1) according to a representative embodiment of the present invention is characterized by comprising: a control circuit (2) for generating a drive control signal for controlling the rotation of a motor; and a drive circuit (3) for driving the motor based on the drive control signal. The control circuit includes: a drive control signal generation unit (20) for generating the drive control signal such that the motor rotates at a target speed, wherein the target speed is a target value of the motor speed; a current measurement unit (24) for measuring the current of the motor; a storage unit (25) for storing current-related thresholds (Ith1, Ith2) established for each target speed; and an anomaly determination unit (26) for determining whether the motor is abnormal based on a comparison result between the measured value of the current and the current-related threshold corresponding to the target speed.

[0018] [2] In the motor drive control device (1) described in [1] above, the threshold related to the current may include a first current threshold (Ith2), the storage unit stores a time threshold (Tth) related to time, and the anomaly determination unit measures the current rise time (Tup) from a first time point (t1) when the measured value of the current is detected to a second time point (t2) when the measured value of the current reaches the first current threshold. If the current rise time is above the time threshold, the motor is determined to be in a specified abnormal state.

[0019] [3] In the motor drive control device described in [2] above, the abnormality determination unit may determine that the measured value of the current has reached the first current threshold if the measured value of the current has been above the first current threshold for a specified time or more.

[0020] [4] In the motor drive control device described in [2] or [3] above, the threshold related to the current may include a second current threshold (Ith1) that is smaller than the first current threshold, and the abnormality determination unit sets the timing when the measured value of the current reaches the second current threshold as the first time point.

[0021] [5] In the motor drive control device described in [4] above, the abnormality determination unit may determine that the measured value of the current has reached the second current threshold if the measured value of the current has been above the second current threshold for a specified time or more.

[0022] [6] In any of the motor drive control devices described in [2] to [5] above, the abnormality determination unit may set the timing of the detection of the increase in the ratio of the change of the measured value of the current with respect to time as the first time point.

[0023] [7] In any of the motor drive control devices described in [2] to [5] above, the abnormality determination unit may determine that the motor is in an abnormal state different from the specified abnormal state when the current rise time is less than the time threshold.

[0024] [8] In any of the motor drive control devices described in [2] to [7] above, the current measuring unit may calculate the average or central value of multiple current detection values ​​and output it as the current measurement value.

[0025] [9] The fan unit (7) of the representative embodiment of the present invention is characterized by comprising: the motor (40); an impeller (41) connected to the output shaft of the motor; and a motor drive control device (1) as described in any one of [1] to [8] above.

[0026]

[10] A representative embodiment of the present invention is a motor drive control method for controlling the rotation of a motor via a motor drive control device. The method is characterized by comprising: a first step (S1), generating a drive control signal for controlling the rotation of the motor such that the motor rotates at a target speed, wherein the target speed is a target value of the motor's rotational speed; a second step (S2), measuring the current of the motor; and a third step (S3-S8), determining whether the motor is malfunctioning based on a comparison between the measured current value and a current-related threshold corresponding to the target speed.

[0027]

[11] In the motor drive control method described in

[10] above, the threshold related to the current may include a first current threshold (Ith2), and the third step may include the following steps: step (S4), measuring the current rise time from a first time point when the measured value of the current starts to rise to a second time point when the measured value of the current reaches the first current threshold; and step (S7), determining that the motor is in a specified abnormal state when the current rise time is above a time threshold that is a time-related threshold.

[0028] 2. Specific examples of implementation methods Hereinafter, specific examples of embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that in the following description, common components in various embodiments will be labeled with the same reference numerals, and repeated descriptions will be omitted.

[0029] Implementation Method Figure 1 This is a block diagram showing the configuration of the fan unit 7 in the embodiment.

[0030] Figure 2 This is a perspective view schematically showing the appearance of the fan unit 7 in the embodiment.

[0031] Figure 3 It is a schematic representation. Figure 2 A cross-sectional view of fan unit 7 shown.

[0032] The fan unit 7 in this embodiment is a device that generates airflow by rotating an impeller. The fan unit 7 can be used, for example, as a cooling device that cools the interior of a device by expelling heat generated inside the device to the outside.

[0033] like Figure 1 As shown, the fan unit 7 includes a fan 4 and a motor drive control device 1.

[0034] Fan 4 includes: a motor 40; and an impeller 41, mounted on a rotating shaft 42 of the motor 40. Fan 4 is, for example, an axial fan. Figure 3 As shown, in fan 4, motor 40 is disposed inside the hub of impeller 41.

[0035] Motor 40 is, for example, an external rotor type three-phase brushless DC (Direct Current) motor having a rotating shaft 42 and a rotor. The rotating shaft 42 is connected to an impeller 41, and the rotor is connected to the rotating shaft 42 and rotates by the rotational force of motor 40. In addition to the rotating shaft 42, motor 40 also includes bearings 43 and 44, a stator 45, a magnet 46, a housing 47, and a circuit board 48.

[0036] like Figure 3 As shown, the rotating shaft 42 is a rod-shaped member with its axis X-direction aligned along its length. Bearings 43 and 44 are supported by a bearing support portion 421 located at the center of the housing 47. Bearings 43 and 44 support the rotating shaft 42 so that it can rotate. Each bearing 43 and 44 has an inner ring, an outer ring, and rolling elements.

[0037] The stator 45 is fixed, for example, near the center (axis X) of the rotating shaft 42 within the housing 47. The stator 45 includes, for example, a stator core formed by stacking multiple electromagnet plates and a coil wound around the stator core with an insulator in between. The magnet 46 functions as a rotor and is provided with a predetermined gap between it and the stator 45. The circuit board 48 is, for example, a printed circuit board (PCB). The circuit board 48, on an insulated substrate with conductive wiring, houses electronic components constituting the motor drive control device 1 (control circuit 2, drive circuit 3, and current detection circuit 6).

[0038] Motor drive control device 1 is a device used to control the drive of motor 40. For example... Figure 1 As shown, the motor drive control device 1 includes, for example, multiple external terminals, a control circuit 2, a drive circuit 3, a position detector 5, and a current detection circuit 6. It should be noted that, alternatively, Figure 1 The components of the motor drive control device 1 shown are part of a whole. In addition to having… Figure 1 In addition to the constituent elements shown, it also has other constituent elements.

[0039] like Figure 1 As shown, the motor drive control device 1 has, for example, a power supply terminal P1, a ground terminal P2, a signal input terminal P3 for input signals, and a signal output terminal P4 for output signals as multiple external terminals.

[0040] Fan unit 7 constitutes a so-called four-wire fan motor. Specifically, as... Figure 1 and Figure 2 As shown, signal line 49 is connected to power terminal P1, signal line 50 is connected to ground terminal P2, signal line 51 is connected to signal input terminal P3, and signal line 52 is connected to signal output terminal P4. Figure 2 As shown, each signal line 49 to 52 is led out to the outside of the housing 47 of the fan unit 7 and connected to a host device (not shown) and a power supply device (not shown) located outside the fan unit 7, thereby electrically connecting the motor drive control device 1 to the power supply device and the host device.

[0041] A DC voltage Vdc is supplied from the power supply unit to the power terminal P1 via signal line 49. This supplies power to the control circuit 2 and the drive circuit 3. It should be noted that a regulator can also be provided in the motor drive control unit 1. The regulator regenerates a DC voltage based on the DC voltage Vdc and supplies it to the control circuit 2 as the power supply voltage. The ground terminal P2 is connected to the ground potential GND via signal line 50.

[0042] As described later, a drive command signal Sc indicating the motor's drive status is input to the signal input terminal P3. For example, if the signal input terminal P3 is connected to a host device, the drive command signal Sc output from the host device is input to the signal input terminal P3. The signal output terminal P4 outputs a rotation status signal So, as described later. For example, if the signal output terminal P4 is connected to a host device, the rotation status signal So output from control circuit 2 is input to the host device from the signal output terminal P4.

[0043] It should be noted that when the fan unit 7 receives power from the host device, the power terminal P1 and the ground terminal P2 can also be connected to the power line and ground line in the host device, respectively.

[0044] The position detector 5 is a device used to detect the rotational position of the rotating shaft (rotor) of the motor 40. The position detector 5 is, for example, a Hall element. For example, three Hall elements corresponding to each phase (U phase, V phase, W phase) of the motor 40 are arranged at approximately equal intervals around the rotor (magnet) of the motor 40. It should be noted that the number of Hall elements is not particularly limited.

[0045] Position detector 5 outputs a rotational position detection signal (Hall signal) Sh to control circuit 2. The rotational position detection signal Sh is a signal representing the rotational position of motor 40, that is, a signal corresponding to the rotational position of the rotor (magnet) of motor 40.

[0046] It should be noted that the position detector 5 only needs to have the function of detecting the position information of the rotating shaft (rotor) of the motor 40 and outputting it as an electrical signal; for example, it can also be a rotary encoder. Alternatively, the position detector 5 can be omitted, and the rotational position of the motor 40 can be detected by a so-called sensorless method. In this sensorless method, the control circuit 2 detects the back electromotive force voltage induced in each phase (U phase, V phase, W phase) of the motor 40, and detects the rotational position of the motor 40 based on the back electromotive force voltage.

[0047] Control circuit 2 is the overall control circuit for the motor drive control device 1. Control circuit 2 generates drive control signals Sd for controlling the rotation of motor 40. Control circuit 2 is, for example, a program processing device (such as a microcontroller or other computer) consisting of a processor (CPU, etc.), various storage devices such as RAM (Random Access Memory) and ROM (Read-Only Memory), and peripheral circuits such as counters (timers), A / D (Analog to Digital) conversion circuits, D / A (Digital to Analog) conversion circuits, clock generation circuits, and input / output (I / F) circuits interconnected via buses and dedicated lines. Details regarding control circuit 2 will be described later.

[0048] The drive circuit 3 is a circuit that drives the motor 40 based on the drive control signal Sd. The drive circuit 3 includes, for example, an inverter circuit (not shown) and a pre-drive circuit (not shown). The inverter circuit outputs a drive signal to the motor 40 based on the output signal from the pre-drive circuit, energizing the three-phase coils of the motor 40. By switching the order in which the three-phase coils are energized, the rotation direction of the motor 40 can be switched. For example, the inverter circuit is configured with a pair of series circuits of two switching elements connected in series between the DC voltage Vdc and the ground potential GND for each phase coil. In each pair of switching elements, the terminals of each phase of the motor 40 are connected to the connection points between the switching elements.

[0049] The pre-drive circuit generates and outputs the output signal for driving the inverter circuit based on the drive control signal Sd. For example, the pre-drive circuit generates and outputs drive signals for each switching element of the inverter circuit based on the drive control signal Sd.

[0050] The drive signal output from the pre-drive circuit turns on / off each of the switching elements constituting the inverter circuit, thereby supplying power to each phase of the motor 40 to make the rotor of the motor 40 rotate.

[0051] The current detection circuit 6 is a circuit that detects the current flowing through the motor 40. For example, the current detection circuit 6 is connected in series with the inverter circuit constituting the drive circuit 3 between the power supply line supplying the DC voltage Vdc and the ground potential GND. In this embodiment, as an example, the current detection circuit 6 is connected between the drive circuit 3 and the ground potential GND.

[0052] The current detection circuit 6 includes, for example, a shunt resistor. When the motor 40 rotates, the current flowing in the coil of the motor 40 flows to the ground potential GND via the shunt resistor of the current detection circuit 6. The current detection circuit 6 outputs the voltage generated across the shunt resistor in response to the current flowing into it as a current detection signal Si. The current detection signal Si is input to the control circuit 2.

[0053] It should be noted that the current detection circuit 6 is not limited to the shunt resistor mentioned above, and can also be other known circuits capable of detecting the current of the motor 40. In addition, at least a portion of the functional parts of the control circuit 2 and the drive circuit 3 (including the current detection circuit 6) can be packaged as a semiconductor integrated circuit device (IC), and the control circuit 2 and the drive circuit 3 (including the current detection circuit 6) can also be packaged as separate semiconductor integrated circuit devices.

[0054] Next, the control circuit 2 will be described in detail.

[0055] The control circuit 2 generates a drive control signal Sd for controlling the rotation of the motor 40 based on the drive command signal Sc input to the signal input terminal P3. Specifically, the control circuit 2 has the function of generating the drive control signal Sd in such a way that the motor 40 is in the rotational state specified by the drive command signal Sc.

[0056] The control circuit 2 has the function of detecting abnormal conditions of the motor 40 (fan 4).

[0057] Here, the abnormal state of motor 40 refers to a state indicating the lifespan of motor 40. For example, control circuit 2 has the function of detecting abnormal states (also called "first abnormal states") caused by, for example, the deterioration of bearings 43 and 44 of motor 40. The abnormal state caused by the deterioration of bearings 43 and 44 of motor 40 will be described below.

[0058] Figure 4 This is a graph illustrating an example of the relationship between a motor's speed and its rated current.

[0059] exist Figure 4 In the figure, the horizontal axis represents the rotational speed, and the vertical axis represents the rated current. Reference numeral 300 indicates the characteristic of the rated current relative to the motor's rotational speed when the motor is in normal operating condition, while reference numeral 301 indicates the characteristic of the rated current relative to the motor's rotational speed when the motor is in abnormal operating condition.

[0060] according to Figure 4 It is generally understood that the higher the motor speed, the higher the rated current. Here, rated current refers to the current flowing through the motor when it rotates at a specific speed. The inventors of this application have discovered that the rated current increases when the motor bearings deteriorate. Specifically, as... Figure 4 As shown, the rated current when the motor rotates at a speed of ω0 is "In0" when the motor is in normal condition, and "In1", which is larger than "In0", when the motor is in an abnormal condition caused by bearing deterioration. Furthermore, the inventors of this application have discovered that the rated current slowly increases as bearing deterioration progresses.

[0061] Therefore, the control circuit 2 of the motor drive control device 1 in this embodiment detects the abnormal state (first abnormal state) caused by the deterioration of the bearings 43 and 44 of the motor 40 by monitoring the current of the motor 40.

[0062] Next, the function blocks used to implement the above-mentioned functions of control circuit 2 will be described.

[0063] like Figure 1As shown, the control circuit 2 includes a drive control signal generation unit 20, a current measurement unit 24, a storage unit 25, and an anomaly determination unit 26 as function blocks for implementing the aforementioned functions. These function blocks, for example, in the control circuit 2, are implemented by the CPU executing various arithmetic operations according to a program stored in memory and controlling peripheral circuits such as the A / D conversion circuit and input / output interface circuit based on the processing results. It should be noted that some or all of the drive control signal generation unit 20, current measurement unit 24, storage unit 25, and anomaly determination unit 26 can also be implemented using dedicated circuits (dedicated hardware logic circuits, etc.).

[0064] The drive control signal generation unit 20 is a functional block that generates a drive control signal Sd. The drive control signal generation unit 20 generates the drive control signal Sd such that the motor 40 rotates at a target speed, where the target speed is a target value for the speed. For example, the drive control signal generation unit 20 includes a target speed setting unit 21, a signal generation unit 22, and a speed calculation unit 23.

[0065] The target speed setting unit 21 is a functional unit for setting the target speed. For example, when a drive command signal Sc is input to the signal input terminal P3 from an external source (host device), the target speed setting unit 21 analyzes the drive command signal Sc input to the signal input terminal P3. For example, consider the following case: the drive command signal Sc is a PWM (Pulse Width Modulation) signal, and the target speed is specified by the duty cycle of the PWM signal. In this case, the correspondence information indicating the relationship between the duty cycle of the PWM signal and the target speed is pre-stored in the storage unit 25. The target speed setting unit 21 analyzes the duty cycle of the PWM signal, and based on the analyzed duty cycle, determines the target speed of the motor 40 by referring to the above-mentioned correspondence information. The target speed setting unit 21 outputs the determined target speed information Stv. It should be noted that, in the case of a fan 4 where the target speed is fixed without inputting a drive command signal Sc, the target speed setting unit 21 can also read and output the target speed information Stv pre-set in the storage unit 25.

[0066] The speed calculation unit 23 is a functional unit that calculates the actual speed of the motor 40. Based on the rotational position detection signal Sh, the speed calculation unit 23 calculates the speed of the motor 40 using a known calculation method and provides the speed information Sv to the signal generation unit 22. It should be noted that, in the sensorless configuration described above, for example, the speed calculation unit 23 may detect the back electromotive force voltage induced in each phase (U phase, V phase, W phase) of the motor 40 and calculate the speed of the motor 40 based on this back electromotive force voltage.

[0067] The signal generation unit 22 generates a drive control signal Sd for the motor 40 based on the target rotational speed information Stv and the rotational speed information Sv of the motor 40. Specifically, the signal generation unit 22 calculates the error between the target rotational speed and the motor rotational speed, and calculates the operating quantity of the motor 40 in such a way that the error becomes zero by means of PID (Proportional Integral Differential) control operation, generates a PWM signal with a duty cycle corresponding to the above operating quantity, and outputs it as the drive control signal Sd.

[0068] It should be noted that, in the case of open-loop control where the motor 40 is to be rotated with a constant force but not maintained at a constant speed, the signal generation unit 22 generates a PWM signal with a duty cycle corresponding to the operating amount used to maintain the target speed and outputs it as a drive control signal Sd.

[0069] The current measuring unit 24 is a functional unit that measures the current of the motor 40. The current measuring unit 24 acquires the detected current value based on the current detection signal Si output from the current detection circuit 6, and generates a measured current value for the motor 40 based on the detected current value. For example, the current measuring unit 24 converts the current detection signal Si, which is an analog signal, into a digital value at a predetermined sampling period, thereby acquiring the detected current value. The current measuring unit 24 generates and outputs the measured current value based on the detected current value. For example, the current measuring unit 24 can output the detected current value as the measured current value, or it can calculate the average value (e.g., a moving average) or the center value (e.g., a moving center value) of multiple detected current values ​​and output it as the measured current value.

[0070] The storage unit 25 is a functional unit that stores various data such as parameters and calculation results used in the calculations to implement the functions described above for the control circuit 2. For example, the storage unit 25 stores correspondence information (Stv-Ith) 250, which represents the correspondence between the target rotational speed of the motor 40 and the current-related threshold of the motor 40 (described later), and information 251, which is a time-related threshold Tth.

[0071] The anomaly determination unit 26 is a functional unit that determines whether the motor 40 is in an abnormal state. Specifically, it determines whether the motor 40 is abnormal based on a comparison between a measured current value and a current-related threshold corresponding to a target rotational speed. The determination method performed by the anomaly determination unit 26 will be described in detail below.

[0072] Figure 5A and Figure 5B This is a graph illustrating an example of how the current in a motor changes over time.

[0073] exist Figure 5Aand Figure 5B In the diagram, the horizontal axis represents time t, and the vertical axis represents the motor current I. Figure 5A The figure shows the change of motor current I over time when the motor enters an abnormal state caused by bearing deterioration (also known as the "first abnormal state"). Figure 5B The figure shows the change of motor current I over time when the motor is in an abnormal state caused by factors other than bearing deterioration (hereinafter also referred to as "second abnormal state").

[0074] As mentioned above, when the motor bearings deteriorate, the motor's rated current will increase. The rate of this current increase is slower than the rate of current increase when an abnormality occurs in the motor due to reasons other than bearing deterioration. For example, when the motor becomes overloaded, the motor current rises sharply, but when the motor bearings deteriorate, the motor's rated current rises slowly.

[0075] Therefore, the abnormality determination unit 26 of the motor drive control device 1 in this embodiment monitors the measured value of the current and the rise time of the current obtained by the current measurement unit 24 based on setting the time threshold related to the time required for the rise of the current of the motor 40 and the current threshold related to the current of the motor 40, thereby determining whether a first abnormal state has occurred.

[0076] In the motor drive control device 1, a current threshold Ith2 is set as a current-related threshold. As mentioned above, the rated current of the motor varies according to the rotational speed. Therefore, the current threshold Ith2 is set for each target rotational speed. For example, a table or function representing the correspondence between the target rotational speed and the current threshold Ith2 (Stv-Ith) is pre-stored in the storage unit 25 as correspondence information 250. In the correspondence information 250, the current threshold Ith2 is set in such a way that the higher the target rotational speed, the higher the current threshold Ith2.

[0077] For example, the anomaly determination unit 26 acquires the target rotational speed information Stv and determines the target rotational speed based on the acquired information. The anomaly determination unit 26 reads the current threshold Ith2 corresponding to the determined target rotational speed from the correspondence information 250, and thereby sets the current threshold Ith2 for each target rotational speed.

[0078] In the motor drive control device 1, a time threshold Tth is set as a time-related threshold. For example, in order to properly detect the rise in rated current as the bearings 43 and 44 of the motor 40 deteriorate, a rise time is measured in advance through experiments or the like as a reference. Based on this measured value, an appropriate value is set and stored as the time threshold Tth in the storage unit 25.

[0079] The anomaly determination unit 26 acquires the measured current value obtained by the current measurement unit 24 at predetermined intervals. The anomaly determination unit 26 measures the current rise time Tup from the time point t1 when the measured current value obtained by the current measurement unit 24 begins to rise until the second time point t2 when the measured current value reaches the current threshold Ith2. If the current rise time Tup is greater than or equal to the time threshold Tth, the anomaly determination unit 26 determines that the motor 40 is in a first abnormal state.

[0080] More specifically, the anomaly detection unit 26 includes, for example, a counter (timing unit). The anomaly detection unit 26 starts the counter when it detects that the measured current value obtained from the current measurement unit 24 has begun to rise, and begins measuring the time. The anomaly detection unit 26 sets the value of the counter to the current rise time Tup.

[0081] After the counter begins measuring the current rise time Tup, the anomaly determination unit 26 determines whether the measured current value has reached or exceeded the current threshold Ith2. For example, if the measured current value (moving average or moving median value) has been at or above the current threshold Ith2 for a specified period of time or more, the anomaly determination unit 26 determines that the measured current value has reached or exceeded the current threshold Ith2 (the measured current value has reached the current threshold Ith2).

[0082] When the measured current value exceeds the current threshold Ith2, the anomaly detection unit 26 stops the counter from measuring the current rise time Tup, and determines whether the current rise time Tup at the time of stopping is above the time threshold Tth. The information 251 of the time threshold Tth is pre-stored in the storage unit 25.

[0083] For example, such as Figure 5A As shown, if the current rise time Tup from the first time point t1 when the measured current value rises to the second time point t2 when the measured current value reaches the current threshold Ith2 is greater than the time threshold Tth, the abnormality determination unit 26 determines that the motor 40 is in a first abnormal state.

[0084] On the other hand, such as Figure 5B As shown, if the current rise time Tup from the first time point t1 when the measured current value rises to the second time point t2 when the measured current value reaches the current threshold Ith2 is less than the time threshold Tth, the anomaly determination unit 26 determines that the motor 40 is not in the first abnormal state. In this case, the anomaly determination unit 26 may also determine that it is in the second abnormal state.

[0085] Here, the determination of whether the measured current value has started to rise can be achieved, for example, by the following method.

[0086] The first method is to use a current threshold Ith1, which is smaller than the current threshold Ith2, as the current-related threshold. Specifically, as the current-related threshold, in addition to setting the current threshold Ith2, a further current threshold Ith1, which is smaller than Ith2, is set. For example, ... Figure 5A As shown, preferably, the current threshold Ith1 is set to a value that is greater than the rated current of the motor 40 and closer to the rated current than the current threshold Ith2. The anomaly determination unit 26 sets the timing of the measured current value reaching the current threshold Ith1 as a first time point t1. For example, it is also possible that if the measured current value (e.g., a moving average or a moving median value) has been above the current threshold Ith1 for a predetermined time or more, the anomaly determination unit 26 determines that the measured current value has reached the current threshold Ith1.

[0087] The second method uses the percentage change of the measured current value. Specifically, the anomaly detection unit 26 sets the timing of detecting an increase in the percentage change of the measured current value relative to time as a first time point t1. For example, the anomaly detection unit 26 acquires the measured current value from the current measurement unit 24 at predetermined intervals. Based on the acquired measured current value and the measured current value acquired in the previous cycle, the anomaly detection unit 26 calculates the percentage change of the measured current value relative to time at predetermined intervals using a known calculation method. Then, the anomaly detection unit 26 monitors the percentage change calculated at predetermined intervals and sets the timing of detecting an increase in the percentage change as the first time point t1.

[0088] It should be noted that the specific method for determining whether the measured current value has started to rise is not limited to the example above, and other methods can also be used.

[0089] Alternatively, the anomaly determination unit 26 may generate a rotational state signal So indicating the rotational state of the motor 40 and output it from the signal output terminal P4. For example, if no anomaly is detected in the motor 40, the anomaly determination unit 26 may generate an FG (Frequency Generator) signal with a frequency based on the rotational position detection signal Sh (Hall signal) or the like using a known method and output it as the rotational state signal So.

[0090] On the other hand, if the motor 40 is detected to be in a first abnormal state, the abnormality determination unit 26 outputs a signal indicating that the motor 40 is in the first abnormal state as a rotation state signal So. For example, the abnormality determination unit 26 outputs a signal with a constant signal level of either a first logic level (DC voltage Vdc) or a second logic level (ground potential) as the rotation state signal So.

[0091] Alternatively, when the anomaly determination unit 26 detects that the motor 40 is in a second abnormal state, it may output a signal indicating that the motor 40 is in a second abnormal state as a rotation state signal So. For example, the anomaly determination unit 26 may output a signal with a logic level opposite to the rotation state signal So output when the motor 40 is detected to be in a first abnormal state as a rotation state signal So.

[0092] Next, the process for determining the abnormal state of the presence or absence of motor 40 will be explained.

[0093] Figure 6 This is a flowchart illustrating an example of the abnormal state determination and processing flow in the motor drive control device 1 of the embodiment.

[0094] For example, the drive control signal generation unit 20 in the control circuit 2 generates a drive control signal Sd in response to the drive command signal Sc input from the outside and supplies it to the drive circuit 3 by the method described above, thereby causing the motor 40 to rotate (step S1).

[0095] After the motor 40 is driven, the current measuring unit 24 in the control circuit 2 begins to measure the current I of the motor 40 (step S2). At this time, the fault determination unit 26 monitors the measured value of the current I of the motor 40 obtained by the current measuring unit 24.

[0096] The anomaly detection unit 26 determines whether the measured value of current I has increased using the method described above (step S3). If the measured value of current I has not increased (step S3: no), the control circuit 2 returns to step S2, drives the motor 40, and continues to measure the current.

[0097] On the other hand, if the measured value of current I increases (step S3: yes), the abnormality determination unit 26 starts measuring the current rise time Tup using the method described above (step S4).

[0098] The anomaly determination unit 26 determines whether the measured value of current I is greater than or equal to the current threshold Ith2 (step S5). If the measured value of current I is less than the current threshold Ith2 (step S5: no), the anomaly determination unit 26 continues to measure the current rise time Tup (step S4).

[0099] If the measured value of current I is above the current threshold Ith2 (step S5: Yes), the anomaly determination unit 26 determines whether the current rise time Tup is above the time threshold Tth (step S6).

[0100] When the current rise time Tup is above the time threshold Tth (step S6: YES), the abnormality determination unit 26 determines that the motor is in the first abnormal state (step S7). In this case, the abnormality determination unit 26 outputs a rotation state signal So indicating that the motor is in the first abnormal state by the above method.

[0101] On the other hand, when the current rise time Tup is less than the time threshold Tth (step S6: NO), the abnormality determination unit 26 determines that the motor is not in the first abnormal state (step S8). In this case, it is also possible that the abnormality determination unit 26 determines that the motor is in the second abnormal state and outputs a rotation state signal So indicating that the motor is in the second abnormal state by the above method.

[0102] As described above, in the motor drive control device 1 of the fan unit 7 according to the embodiment, the control circuit 2 generates a drive control signal Sd so that the motor 40 rotates at a target speed, and determines whether the motor 40 is abnormal based on the comparison result between the current-related threshold corresponding to each target speed and the measured value of the current of the motor 40. Thus, even when the speed of the motor 40 is controlled by closed-loop control, it is possible to detect an abnormal state of the motor in which a sign of the life of the motor 40 appears as a change in the current of the motor.

[0103] Specifically, the control circuit 2 measures the current rise time Tup from the first time point t1 when the measured value of the current starts to rise to the second time point t2 when the measured value of the current reaches the current threshold Ith2. When the current rise time Tup is above the time threshold Tth, it is determined that the motor 40 is in the first abnormal state. Thus, as described above, it is possible to detect a sign of the life of the motor 40 caused by deterioration of the bearings 43 and 44 of the motor 40.

[0104] Here, the control circuit 2 sets the timing when the measured value of the current reaches the current threshold Ith1 (<Ith2) as the first time point t1, whereby it is possible to easily detect the start of the rise of the measured value of the current. In addition, the control circuit 2 sets the timing when an increase in the change ratio of the measured value of the current with respect to time is detected as the first time point t1, whereby it is possible to easily detect the start of the rise of the measured value of the current.

[0105] In addition, when the current rise time Tup is less than the time threshold Tth, the control circuit 2 determines that the motor 40 is in the second abnormal state. Thus, it is also possible to detect an abnormal state in which the current of the motor rises due to reasons other than deterioration of the bearings 43 and 44 of the motor 40.

[0106] Furthermore, as described above, the control circuit 2 may calculate the average value (e.g., moving average) or central value (e.g., moving central value) of multiple currents and set it as the measured value of the current. This can suppress the erroneous sensing of the first time point t1 and the second time point t2 due to the abrupt change in the microscopic current value caused by fluctuations in the detected current value.

[0107] Furthermore, as described above, the control circuit 2 may determine that the measured current value has reached the current threshold Ith1 (Ith2) if the measured current value (e.g., moving average or moving median value) has been above the current threshold Ith1 (Ith2) for a specified period of time. This allows for more reliable suppression of false sensing at the first time point t1 and the second time point t2.

[0108] Extension of Implementation Methods The invention made by the inventor has been specifically described above based on the embodiments. However, the invention is not limited thereto and various modifications can be made without departing from its spirit.

[0109] For example, in the above embodiment, the case where the abnormal state of the detection object obtained by the motor drive control device 1 is an abnormal state caused by the deterioration of the motor bearing has been described, but it is not limited to this. That is, other abnormal states in which the motor current slowly rises due to reasons other than the deterioration of the motor bearing can also be set as the detection object.

[0110] Furthermore, in the above embodiment, an example of a three-phase brushless motor 40 is shown, but the type and number of phases of motor 40 are not limited to this. For example, motor 40 can also be a single-phase brushless motor.

[0111] Furthermore, the flowchart above illustrates one example of an action and is not limiting. That is, the steps shown in each diagram of the flowchart are specific examples and are not limited to that process. For example, the order of some processes can be changed, other processes can be inserted between processes, and some processes can be performed in parallel.

[0112] Explanation of reference numerals in the attached figures 1: Motor drive control device; 2: Control circuit; 3: Drive circuit; 4: Fan; 5: Position detector; 6: Current detection circuit; 7: Fan unit; 20: Drive control signal generation unit; 21: Target speed setting unit; 22: Signal generation unit; 23: Speed ​​calculation unit; 24: Current measurement unit; 25: Storage unit; 26: Anomaly determination unit; 40: Motor; 41: Impeller; 42: Rotating shaft; 43, 44: Bearings; 45: Stator; 46: Magnet; 47: Housing; 48: Circuit board; 49-52: Signal lines; 421: Bearing support; Ith1: Current threshold (second current threshold); Ith2: Current threshold (first current threshold); I: Motor current; t1: First time point; t2: Second time point; Tth: Time threshold; Tup: Current rise time.

Claims

1. A motor drive control device, comprising: The control circuit generates drive control signals to control the rotation of the motor; as well as The drive circuit drives the motor based on the drive control signal. The control circuit has: The drive control signal generation unit generates the drive control signal in such a way that the motor rotates at a target speed, wherein the target speed is a target value of the motor's speed. The current measuring unit measures the current of the motor. The storage unit stores current-related thresholds for each target rotational speed; and The anomaly determination unit determines whether the motor is abnormal based on a comparison between the measured value of the current and a threshold related to the current corresponding to the target rotational speed.

2. The motor drive control device according to claim 1, wherein, The thresholds related to the current include a first current threshold. The storage unit stores time-related time thresholds. The anomaly determination unit measures the current rise time from a first time point when the measured value of the current starts to rise until a second time point when the measured value of the current reaches the first current threshold. If the current rise time is above the time threshold, the unit determines that the motor is in a specified abnormal state.

3. The motor drive control device according to claim 2, wherein, If the measured current value has been above the first current threshold for a specified period of time, the anomaly determination unit determines that the measured current value has reached the first current threshold.

4. The motor drive control device according to claim 2, wherein, The thresholds related to the current include a second current threshold that is smaller than the first current threshold. The anomaly determination unit sets the time at which the measured value of the current reaches the second current threshold as the first time point.

5. The motor drive control device according to claim 4, wherein, If the measured current value has been above the second current threshold for a specified period of time, the anomaly determination unit determines that the measured current value has reached the second current threshold.

6. The motor drive control device according to claim 2, wherein, The anomaly determination unit sets the timing of the increase in the ratio of the measured value of the current to the change in time as the first time point.

7. The motor drive control device according to claim 2, wherein, If the current rise time is less than the time threshold, the anomaly determination unit determines that the motor is in an abnormal state different from the specified abnormal state.

8. The motor drive control device according to claim 2, wherein, The current measuring unit calculates the average or median value of multiple current detection values ​​and outputs it as the measured value of the current.

9. A fan unit comprising: motor; Impeller, connected to the output shaft of the motor; and The motor drive control device according to any one of claims 1 to 8.

10. A motor drive control method for controlling the rotation of a motor via a motor drive control device, the motor drive control method comprising: The first step is to generate a drive control signal for controlling the rotation of the motor in such a way that the motor rotates at a target speed, wherein the target speed is a target value of the motor's rotation speed; The second step is to measure the current of the motor; and The third step is to determine whether the motor is abnormal based on the comparison between the measured value of the current and the current-related threshold corresponding to the target speed.

11. The motor drive control method according to claim 10, wherein, The thresholds related to the current include a first current threshold. The third step includes the following steps: The current rise time is measured from a first time point when the measured value of the current begins to rise until a second time point when the measured value of the current reaches the first current threshold; and If the current rise time is above a time threshold that is a time-related threshold, the motor is determined to be in a specified abnormal state.

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