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

Abstract

The present invention enables switching of the rotation direction of a motor while ensuring a wide setting range of the rotation speeds of the motor. In a motor drive control device (1), a control circuit (2) generates a drive control signal (Sd) so that a motor (40) rotates at a rotation speed designated by a second signal (S2) appearing at a signal input terminal (P3) in the rotation direction designated by a first signal (S1) appearing at a signal input / output terminal (P4), and generates a rotation state signal (So) indicating the rotation state of the motor (40).

Description

Motor Drive Control Device, Fan Unit, and Motor Drive Control Method

[0001] The present invention relates to a motor drive control device, a fan unit, and a motor drive control method, and more particularly to a motor drive control device for controlling the rotation of a motor in a fan unit.

[0002] Conventionally, a fan (fan motor) is widely known as a cooling device that discharges heat generated inside electrical equipment or the like to the outside and cools the inside of the equipment. The fan has a motor and an impeller connected to the output shaft of the motor, and generates an air flow (wind) as the impeller rotates in response to the rotation of the output shaft of the motor. The fan, for example, constitutes a single fan unit together with a motor drive control device for controlling the drive of the fan motor.

[0003] Generally, in a fan unit, when the motor drive control device drives the motor in response to an instruction from a higher-level device, the fan (motor) rotates in one direction at a constant rotational speed. On the other hand, when the fan unit is used for a long period of time, dust may adhere to the impeller or the like, making it difficult for the motor to rotate. In particular, in the case of a fan used outdoors, dust, sand, and the like are likely to adhere. Therefore, a fan unit having a function of rotating the fan in the reverse direction for the purpose of dust removal of the fan is known.

[0004] For example, Patent Document 1 discloses a technique in which the fan is rotated forward when the duty ratio of a PWM signal for specifying the rotational speed is between 5% and 45%, and the fan is rotated backward when the duty ratio of the PWM signal is between 55% and 95%.

[0005] U.S. Patent No. 10,060,438

[0006] However, according to the technique disclosed in Patent Document 1, since the rotation direction of the motor (fan) is specified by the range of the duty ratio of the PWM signal, there is a problem that the range of the rotational speed that can be set by the duty ratio of the PWM signal becomes narrow.

[0007] This invention has been made in view of the above-mentioned problems, and aims to enable switching of the motor's rotation direction while ensuring a wide range of motor rotation speed settings.

[0008] A motor drive control device according to a typical embodiment of the present invention is characterized by comprising: a signal input terminal; a signal input / output terminal; a control circuit that generates a drive control signal for controlling the rotation of the motor so that the motor rotates in a rotation direction specified by a first signal appearing at the signal input / output terminal and at a rotation speed specified by a second signal appearing at the signal input terminal, and also generates a rotation state signal indicating the rotation state of the motor; and a drive circuit that drives the motor based on the drive control signal.

[0009] According to the motor drive control device of the present invention, it is possible to switch the rotation direction of the motor while ensuring a wide range of setting ranges for the motor's rotation speed.

[0010] This is a diagram showing the configuration of a fan system equipped with a fan unit according to Embodiment 1. This is a block diagram showing the configuration of a fan unit according to Embodiment 1. This is a schematic perspective view showing the external appearance of a fan unit according to Embodiment 1. This is a flowchart showing an example of the processing flow by a motor drive control device according to Embodiment 1. This is a diagram showing an example of the relationship between a drive command signal and the operating state of a fan in a fan unit according to Embodiment 1. This is a diagram showing the configuration of a fan system equipped with a fan unit according to Embodiment 2. This is a block diagram showing the configuration of a fan unit according to Embodiment 2. This is a flowchart showing an example of the processing flow by a motor drive control device according to Embodiment 2. This is a diagram showing an example of the relationship between a drive command signal and the operating state of a fan in a fan unit according to Embodiment 2. This is a diagram showing another example of the relationship between a drive command signal and the operating state of a fan in a fan unit according to Embodiment 2.

[0011] 1. Outline of Embodiments First, a general overview of a typical embodiment of the invention disclosed in this application will be given. In the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are indicated in parentheses.

[0012] [1] A motor drive control device (1, 1A) according to a typical embodiment of the present invention is characterized by comprising: a signal input terminal (P3); a signal input / output terminal (P4); a control circuit (2, 2A) that generates a drive control signal (Sd) for controlling the rotation of the motor so that the motor (40) rotates in the rotation direction specified by a first signal (S1) appearing at the signal input / output terminal and at the rotation speed specified by a second signal (S2) appearing at the signal input terminal, and also generates a rotation state signal (So) indicating the rotation state of the motor; and a drive circuit (3) that drives the motor based on the drive control signal.

[0013] [2] In the motor drive control device (1) described in [1] above, the control circuit (2) may stop outputting the rotation status signal from the signal input / output terminal when it detects that the motor is stopped, and output the rotation status signal from the signal input / output terminal when it detects that the motor is not stopped.

[0014] [3] In the motor drive control device described in [2] above, the control circuit includes a rotation state signal generation unit (25) that detects the rotation state of the motor and generates and outputs the rotation state signal, an output control unit (26) that switches whether or not to output the rotation state signal from the signal input / output terminal (P4), and a drive control signal generation unit (20) that determines whether or not the motor is rotating based on the rotation state signal and generates the drive control signal, wherein the drive control signal generation unit analyzes the first signal to identify the specified rotation direction and generates information (Str) of the specified rotation direction, and analyzes the second signal to identify The output control unit includes a drive command analysis unit (21) that identifies the rotational speed and generates information (Stv) of the specified rotational speed, a signal generation unit (22) that generates the drive control signal based on the information of the specified rotational direction and the information of the specified rotational speed, and a motor stop determination unit (24) that determines whether or not the motor is stopped. The output control unit may stop outputting the rotational status signal from the signal input / output terminal when the motor stop determination unit determines that the motor is stopped, and output the rotational status signal from the signal input / output terminal when the motor stop determination unit determines that the motor is not stopped.

[0015] [4] In the motor drive control device described in [3] above, the rotation status signal is a signal having a frequency corresponding to the actual rotation speed of the motor, and the motor stop determination unit may determine that the motor is not stopped if the frequency of the rotation status signal is equal to or greater than a threshold, and determine that the motor is stopped if the frequency of the rotation status signal is lower than the threshold.

[0016] [5] In the motor drive control device described in [4] above, the drive command analysis unit may analyze the first signal after a predetermined period (Txs) has elapsed since the motor stop determination unit determined that the motor has stopped.

[0017] [6] In the motor drive control device described in any one of [1] to [5] above, the drive command analysis unit may determine that a first direction is specified as the rotation direction when the first signal satisfies a first condition, and determine that a second direction opposite to the first direction is specified as the rotation direction when the first signal satisfies a second condition different from the first condition.

[0018] [7] In the motor drive control device (1A) described in [1] above, the signal input / output terminal is an open terminal and is pulled up to a predetermined voltage via a load (Rpu), the high level of the first signal is a voltage corresponding to the predetermined voltage, and the control circuit may specify the designated direction of rotation based on the magnitude of the high-level voltage of the first signal.

[0019] [8] In the motor drive control device described in [7] above, the predetermined voltage may be a first voltage (5V) or a second voltage (12V) that is greater than the first voltage.

[0020] [9] In the motor drive control device described in [7] or [8] above, the control circuit includes a rotation state signal generation unit (25A) that detects the rotation state of the motor and generates the rotation state signal by driving the load connected to the signal input / output terminal according to the detected rotation state, and a drive control signal generation unit (20A) that generates the drive control signal, wherein the drive control signal generation unit includes a drive command analysis unit (21A) that analyzes the first signal appearing at the signal input / output terminal to identify a specified rotation direction and generates information on the specified rotation direction, and analyzes the second signal to identify a specified rotation speed and generates information on the specified rotation speed, and a signal generation unit (22) that generates the drive control signal based on the information on the specified rotation direction and the information on the specified rotation speed, wherein the drive command analysis unit may determine that a first direction is specified as the rotation direction when the high level of the first signal appearing at the signal input / output terminal is greater than a threshold (Vth), and may determine that a second direction opposite to the first direction is specified as the rotation direction when the high level of the first signal appearing at the signal input / output terminal is less than the threshold.

[0021]

[10] A fan unit (6, 6A) according to a typical 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, 1A) according to any one of [1] to

[11] above.

[0022]

[11] A typical embodiment of the present invention is a motor drive control method for controlling the rotation of a motor (40) using a motor drive control device (1) having a signal input terminal (P3) and a signal input / output terminal (P4). The method is characterized by including: a first step (S13, S13A) of identifying a specified rotation direction based on a first signal (S1, So) appearing at the signal input / output terminal; a second step (S14) of identifying a specified rotation speed based on a second signal (S2) appearing at the signal input terminal; a third step (S15) of generating a drive control signal (Sd) for controlling the rotation of the motor so that the motor rotates in the rotation direction identified in the first step and at the rotation speed identified in the second step; and a fourth step (S16) of generating a rotation state signal (So) corresponding to the rotation state of the motor.

[0023] 2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the figures. In the following description, common components in each embodiment will be denoted by the same reference numerals, and repeated explanations will be omitted.

[0024] <Embodiment 1> Figure 1 is a diagram showing the configuration of a fan system 100 equipped with a fan unit 6 according to Embodiment 1.

[0025] As shown in Figure 1, the fan system 100 includes a fan unit 6 and a higher-level device 7. The fan unit 6 is a device that generates airflow by rotating an impeller. The fan unit 6 can be used, for example, as a cooling device to expel heat generated inside equipment to the outside and cool the inside of the equipment.

[0026] As shown in Figure 1, the fan unit 6 comprises a fan 4 and a motor drive control device 1. The fan 4 comprises a motor 40 and an impeller 41 attached to the rotating shaft of the motor 40. The fan 4 is, for example, an axial flow fan. The motor 40 is, for example, a three-phase brushless DC (Direct Current) motor. The motor drive control device 1 is a device for controlling the drive of the motor 40. Details of the motor drive control device 1 will be described later.

[0027] The higher-level device 7 is a device that controls the operation of the fan unit 6. For example, when the fan unit 6 is installed inside an information processing device such as a personal computer or a server, the higher-level device 7 functions as a program processing device or the like that realizes the main functions of the information processing device.

[0028] The higher-level device 7 has, for example, external terminals Po and Pio. Here, external terminal Po is an output terminal, and external terminal Pio is an input / output terminal. The higher-level device 7 outputs a drive command signal Sc from external terminals Po and Pio and inputs it to the fan unit 6, thereby controlling the fan unit 6 so that the fan 4 reaches the target drive state.

[0029] Here, the drive command signal Sc is a signal that indicates the target drive state of the motor 40 (fan 4) in the fan unit 6. The drive command signal Sc includes, for example, a rotation direction specification signal S1 that specifies the rotation direction of the motor 40, and a rotation speed specification signal S2 that specifies the target rotation speed (target rotation speed) of the motor 40.

[0030] The host device 7 outputs a rotation direction specification signal S1 from the external terminal Pio, and the rotation direction specification signal S1 is input to the signal input / output terminal P4 of the motor drive control device 1, which will be described later. The host device 7 also outputs a rotation speed specification signal S2 from the external terminal Po, and the rotation speed specification signal S2 is input to the signal input terminal P3 of the motor drive control device 1, which will be described later. Furthermore, when the host device 7 is not outputting the rotation direction specification signal S1 from the external terminal Pio, it monitors the operating state of the fan 4 (motor 40) in the fan unit 6 by analyzing the rotation state signal So, which indicates the rotation state of the motor 40 and is input from the fan unit 6 to the external terminal Pio. Details of the rotation direction specification signal S1, the rotation speed specification signal S2, and the rotation state signal So will be described later.

[0031] Next, we will describe the details of the motor drive control device 1.

[0032] Figure 2 is a block diagram showing the configuration of the fan unit 6 according to Embodiment 1. Figure 3 is a schematic perspective view showing the external appearance of the fan unit 6 according to Embodiment 1.

[0033] As shown in Figure 2, the motor drive control device 1 includes a plurality of external terminals, a control circuit 2, a drive circuit 3, and a position detector 5. Note that the components of the motor drive control device 1 shown in Figure 1 are only a part of the whole, and the motor drive control device 1 may have other components in addition to those shown in Figure 1.

[0034] Specifically, the motor drive control device 1 has the following external terminals: a power terminal P1, a ground terminal P2, a signal input terminal P3 for inputting signals, and a signal input / output terminal P4 for inputting or outputting signals.

[0035] The fan unit 6 constitutes a so-called four-wire fan motor. Specifically, as shown in Figures 2 and 3, a signal line 49 is connected to the power terminal P1, a signal line 50 is connected to the ground terminal P2, a signal line 51 is connected to the signal input terminal P3, and a signal line 52 is connected to the signal input / output terminal P4. As shown in Figure 3, each of the signal lines 49 to 51 is brought out to the outside of the casing 47 of the fan unit 6 and connected to the host device 7 and power supply (DC voltage Vdc) located outside the fan unit 6, thereby electrically connecting the motor drive control device 1 to the host device 7 and power supply.

[0036] A DC voltage Vdc is supplied to the power terminal P1 from the power supply unit via the signal line 49. This supplies the DC voltage Vdc as the power supply voltage to the control circuit 2 and the drive circuit 3. Alternatively, a regulator may be provided in the motor drive control device 1, which generates a new DC voltage from the DC voltage Vdc and supplies that DC voltage as the power supply voltage to the control circuit 2. The ground terminal P2 is connected to the ground potential GND via the signal line 50.

[0037] The rotation speed specification signal S2 is input to the signal input terminal P3. Specifically, the signal input terminal P3 and the external terminal Po of the host device 7 are connected by a signal line 51, and the rotation speed specification signal S2 output from the external terminal Po of the host device 7 is input to the signal input terminal P3 via the signal line 51.

[0038] The rotation direction specification signal S1 is input to the signal input / output terminal P4. Specifically, the signal input / output terminal P4 and the external terminal Pio of the host device 7 are connected by a signal line 52, and the rotation direction specification signal S1 output from the external terminal Pio of the host device 7 is input to the signal input / output terminal P4 via the signal line 52. For example, if the external terminal Pio in the host device 7 is pulled up to the power supply voltage (5V or 12V) via a resistor and the output of the rotation status signal So is stopped, the power supply voltage as the pull-up voltage is input to the signal input / output terminal P4 as the rotation direction specification signal S1. Also, for example, if the external terminal Pio in the host device 7 is pulled down to the ground voltage (0V) via a resistor and the output of the rotation status signal So is stopped, the ground voltage as the pull-down voltage is input to the signal input / output terminal P4 as the rotation direction specification signal S1.

[0039] Furthermore, the pull-up voltage may be switchable by control from the higher-level device 7. For example, the pull-up voltage may be switchable by the higher-level device 7 between a first voltage (e.g., 5V) and a second voltage greater than the first voltage (e.g., 12V).

[0040] Furthermore, a rotation status signal So is output from the signal input / output terminal P4. The rotation status signal So output from the signal input / output terminal P4 is input to the external terminal Pio of the host device 7 via the signal line 52.

[0041] Furthermore, if the fan unit 6 receives power via the host device 7, the power terminal P1 and ground terminal P2 may be connected to the power line and ground line within the host device 7, respectively.

[0042] The position detector 5 is a device for detecting the rotational position of the rotation axis (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 around the rotor (magnet) of the motor 40 at approximately equal intervals from each other. The number of Hall elements is not particularly limited.

[0043] The position detector 5 outputs a rotation position detection signal (Hall signal) Sh to the control circuit 2. The rotation position detection signal Sh is a signal indicating the rotation position of the motor 40, that is, a signal corresponding to the rotation position of the rotor (magnet) of the motor 40.

[0044] Note that the position detector 5 only needs to have the function of detecting the position information of the rotation axis (rotor) of the motor 40 and outputting it as an electric signal. For example, it may be a rotary encoder. Alternatively, without providing the position detector 5, the control circuit 2 may detect the back electromotive voltage induced in each phase (U phase, V phase, W phase) of the motor 40, and detect the rotation position of the motor 40 by a so-called sensorless method based on the back electromotive voltage.

[0045] The control circuit 2 is a circuit that performs overall control in the motor drive control device 1. The control circuit 2 generates a drive control signal Sd for controlling the rotation of the motor 40. The control circuit 2 is, for example, a program processing device (such as various computers such as a microcontroller) having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, 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 I / F circuit are connected to each other via a bus or a dedicated line. Details of the control circuit 2 will be described later.

[0046] The drive circuit 3 is a circuit that drives the motor 40 based on the drive control signal Sd. The drive circuit 3 has, 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 output from the pre-drive circuit, and energizes the three-phase coils provided in the motor 40. By switching the order of energizing the three-phase coils, the rotation direction of the motor 40 can be switched. For example, the inverter circuit is configured such that pairs of series circuits of two switch elements connected in series between the DC voltage Vdc and the ground potential GND are respectively arranged for each phase coil. In each pair of two switch elements, the terminals of each phase of the motor 40 are connected to the connection point between the switch elements.

[0047] The pre-drive circuit generates an output signal for driving the inverter circuit based on the drive control signal Sd and outputs it to the inverter circuit. For example, the pre-drive circuit generates and outputs a drive signal for driving each switch element of the inverter circuit based on the drive control signal Sd.

[0048] The drive signal output from the pre-drive circuit turns on / off each switch element constituting the inverter circuit, thereby supplying power to each phase of the motor 40 and rotating the rotor of the motor 40.

[0049] In the motor drive control device 1, at least a part of the functional parts of the control circuit 2 and the drive circuit 3 may be packaged as one semiconductor integrated circuit device (IC: Integrated Circuit), or the drive circuit 3 and the control circuit 2 may be packaged as individual semiconductor integrated circuit devices.

[0050] Next, the control circuit 2 will be described in detail.

[0051] The control circuit 2 has a function of detecting whether the motor 40 is stopped and making the signal input / output terminal P4 function as an input terminal or an output terminal based on the detection result. Specifically, when the control circuit 2 detects that the motor 40 is stopped, it stops outputting the rotation state signal So (pulse) from the signal input / output terminal P4, thereby making the signal input / output terminal P4 function as an input terminal. On the other hand, when the control circuit 2 detects that the motor 40 is not stopped, it outputs the rotation state signal So (pulse) from the signal input / output terminal P4, thereby making the signal input / output terminal P4 function as an output terminal.

[0052] The control circuit 2 specifies the rotation direction of the motor 40 specified from the rotation direction designation signal S1 as the first signal appearing at the signal input / output terminal P4, and also specifies the rotation speed (target rotation speed) of the motor 40 specified from the rotation speed designation signal S2 as the second signal appearing at the signal input terminal P3, and has a function of generating the drive control signal Sd based on the specified rotation direction information and rotation speed information.

[0053] As shown in Figure 1, the control circuit 2 includes a drive control signal generation unit 20, a rotation state signal generation unit 25, and an output control unit 26 as functional blocks for realizing the above-described functions. These functional blocks are realized, for example, in the control circuit 2 by the CPU executing various calculation processes according to a program stored in memory, and controlling peripheral circuits such as A / D conversion circuits and input / output interface circuits based on the processing results.

[0054] Furthermore, some or all of the drive control signal generation unit 20, rotation state signal generation unit 25, and output control unit 26 may be implemented by dedicated circuits (such as dedicated hardware logic circuits). For example, the output control unit 26 may be implemented by a switch consisting of a transistor or the like.

[0055] The drive control signal generation unit 20 is a functional block that generates a drive control signal Sd so that the motor 40 rotates at a target rotational speed specified in either the first direction or a second direction opposite to the first direction, based on a rotation direction specification signal S1 as a first signal appearing at the signal input / output terminal P4 and a rotation speed specification signal S2 as a second signal appearing at the signal input terminal P3.

[0056] In the following explanation, the first direction may be referred to as the "forward direction," rotation in the forward direction as "positive rotation," the second direction as the "reverse direction," and rotation in the reverse direction as "negative rotation."

[0057] Details of the drive control signal generation unit 20 will be described later.

[0058] The rotation state signal generation unit 25 is a functional block that detects the rotation state of the motor 40 and generates a rotation state signal So indicating the rotation state of the motor 40. Based on the rotation position detection signal Sh output from the position detector 5, the rotation state signal generation unit 25 generates a rotation state signal So indicating the rotation state of the motor and outputs it to a predetermined node Np.

[0059] Here, the rotational status signal So is, for example, a pulse with a frequency based on the actual rotational speed of the motor 40. Specifically, the rotational status signal So is an FG (Frequency Generator) signal having a frequency corresponding to the rotational speed of the motor 40 and a duty cycle of 50%. The rotational status signal generation unit 25 generates an FG signal by a known method based on, for example, a Hall signal as a rotational position detection signal Sh, and outputs it to node Np as the rotational status signal So.

[0060] For example, if the external terminal Pio is pulled up via a resistor within the host device 7, the rotational status signal generation unit 25 generates a rotational direction specification signal S1 in which the pull-up voltage (e.g., 5V or 12V) becomes high and the ground voltage of the control circuit 2 becomes low. Also, for example, if the external terminal Pio is pulled down via a resistor within the host device 7, the rotational status signal generation unit 25 generates a rotational direction specification signal S1 in which the power supply voltage (e.g., 5V) of the control circuit 2 becomes high and the pull-down voltage (0V) becomes low. In other words, one of the voltage levels of the rotational status signal So is either the pull-up voltage or the pull-down voltage.

[0061] The rotational status signal generation unit 25 may also output information indicating the rotation direction of the motor 40 in the rotational status signal So. For example, when the motor 40 is rotating in the forward direction, the rotational status signal generation unit 25 may output a signal as the rotational status signal So that has a frequency corresponding to the period of the rotational position detection signal Sh and a duty cycle of 50%. On the other hand, when the motor 40 is rotating in the negative direction, the rotational status signal generation unit 25 may output a signal as the rotational status signal So that has a frequency corresponding to the period of the rotational position detection signal Sh and a duty cycle other than 50%.

[0062] The output control unit 26 is a functional unit that switches whether or not to output the rotation status signal So from the signal input / output terminal P4. The output control unit 26 switches whether or not to output the rotation status signal So from the signal input / output terminal P4 according to the determination result by the motor stop determination unit 24, which will be described later. For example, if the motor stop determination unit 24 determines that the motor 40 is stopped, the output control unit 26 stops outputting the rotation status signal So from the signal input / output terminal P4, and if the motor stop determination unit 24 determines that the motor 40 is not stopped, it outputs the rotation status signal So from the signal input / output terminal P4.

[0063] Next, the details of the drive control signal generation unit 20 will be described.

[0064] The drive control signal generation unit 20 determines whether the motor 40 is rotating based on the rotation status signal So, and generates a drive control signal Sd based on the rotation direction specification signal S1 and the rotation speed specification signal S2.

[0065] As described above, the rotation direction specification signal S1 is a signal that specifies the rotation direction of the motor 40. The host device 7 generates signals of different types depending on the rotation direction of the motor 40 to be specified and outputs them as the rotation direction specification signal S1 from the external terminal Pio. Specifically, when the rotation direction of the motor 40 is specified as forward (positive rotation), the host device 7 outputs a rotation direction specification signal S1 that satisfies the first condition, and when the rotation direction of the motor 40 is specified as reverse (negative rotation), it outputs a rotation direction specification signal S1 that satisfies the second condition, which is different from the first condition.

[0066] Here, the first condition is that at least one of the voltage, frequency, and duty cycle of the rotation direction specification signal S1 is a first value or within a first range, and the second condition is that at least one of the voltage, frequency, and duty cycle of the rotation direction specification signal S1 is a second value different from the first value or within a second range different from the first range.

[0067] For example, the first condition is that the rotation direction designation signal S1 is 5V, and the second condition is that the rotation direction designation signal S1 is 0V. Alternatively, the first condition is that the rotation direction designation signal S1 is 12V, and the second condition is that the rotation direction designation signal S1 is 5V. Or, the first condition is that the rotation direction designation signal S1 is a pulse with a frequency of 10kHz and a duty cycle of 50%, and the second condition is that the rotation direction designation signal S1 is a pulse with a frequency of 5kHz and a duty cycle of 50%. Note that the first and second conditions are not limited to the examples above.

[0068] In Embodiment 1, as an example, the first condition is that the rotation direction specification signal S1 is 5V, and the second condition is that the rotation direction specification signal S1 is 0V.

[0069] As described above, the rotation speed specification signal S2 is a signal that specifies the target rotation speed (target rotation speed) of the motor 40. The rotation speed specification signal S2 is a binary signal and has a voltage corresponding to a first logic level or a second logic level opposite to the first logic level. In Embodiment 1, as an example, the first logic level is set to a low level (e.g., ground voltage) and the second logic level is set to a high level (e.g., DC voltage Vdc), but it is not limited to this.

[0070] In Embodiment 1, the rotational speed specification signal S2 is, for example, a PWM signal having a duty cycle corresponding to the specified target rotational speed. The host device 7 generates a PWM signal having a duty cycle corresponding to the specified target rotational speed and outputs it as the rotational speed specification signal S2 from the external terminal Po.

[0071] For example, as shown in Figure 2, the drive control signal generation unit 20 includes a drive command analysis unit 21, a signal generation unit 22, a rotation speed calculation unit 23, a motor stop determination unit 24, and a rotation state signal generation unit 25.

[0072] The drive command analysis unit 21 analyzes the rotation direction specification signal S1 input to the signal input / output terminal P4 and the rotation speed specification signal S2 input to the signal input terminal P3.

[0073] Specifically, the drive command analysis unit 21 analyzes the rotation direction specification signal S1 to identify the specified rotation direction and generates information indicating the specified rotation direction (also referred to as "specified rotation direction information") Str. More specifically, the drive command analysis unit 21 determines that "forward direction (positive rotation)" is specified as the rotation direction if the rotation direction specification signal S1 satisfies the first condition, and determines that "reverse direction (negative rotation)" is specified as the rotation direction if the rotation direction specification signal S1 satisfies the second condition.

[0074] For example, when the motor 40 is stopped and the signal input / output terminal P4 is functioning as an input terminal, if the rotation direction specification signal S1 input to the signal input / output terminal P4 is 5V, the drive command analysis unit 21 determines that the rotation direction of the motor 40 is specified as "forward (positive rotation)" and generates specified rotation direction information Str indicating "forward (positive rotation)". On the other hand, if the rotation direction specification signal S1 input to the signal input / output terminal P4 is 0V, the drive command analysis unit 21 determines that the rotation direction of the motor 40 is specified as "reverse (negative rotation)" and generates specified rotation direction information Str indicating "reverse (negative rotation)".

[0075] Furthermore, the drive command analysis unit 21 analyzes the rotation speed specification signal S2 to identify the specified target rotation speed and generates information indicating the specified target rotation speed (also referred to as "specified rotation speed information") Stv. For example, information of a table or function representing the correspondence between the duty cycle of the PWM signal as the rotation speed specification signal S2 and the target rotation speed is pre-stored in the memory device within the control circuit 2. The drive command analysis unit 21 analyzes the duty cycle of the rotation speed specification signal S2 and, using the above table or function, determines the target rotation speed corresponding to the analyzed duty cycle and generates specified rotation speed information Stv indicating the target rotation speed.

[0076] The drive command analysis unit 21 provides the specified rotation direction information Str and specified rotation speed information Stv, generated by the method described above, to the signal generation unit 22.

[0077] The rotational speed calculation unit 23 is a functional unit that calculates the actual rotational speed of the motor 40. Based on the rotational position detection signal Sh, the rotational speed calculation unit 23 calculates the actual rotational speed of the motor 40 using a known calculation method and provides the actual rotational speed information Sv, which indicates the actual rotational speed, to the signal generation unit 22. In the case of the sensorless method described above, for example, the rotational speed calculation unit 23 may detect the back electromotive force induced in each phase (U phase, V phase, W phase) of the motor 40 and calculate the actual rotational speed of the motor 40 based on that back electromotive force.

[0078] The signal generation unit 22 generates a drive control signal Sd for the motor 40 based on the specified rotation direction information Str, the specified rotation speed information Stv, and the actual rotation speed information Sv. Specifically, the signal generation unit 22 calculates the error between the specified rotation speed (target rotation speed) and the actual rotation speed of the motor 40, and calculates the control amount for the motor 40 so that the error becomes zero, for example, by PID (Proportional Integral Differential) control calculation. Then, the signal generation unit 22 generates a PWM signal having a duty cycle corresponding to the control amount so that the motor 40 rotates in the specified rotation direction, and outputs it as the drive control signal Sd.

[0079] Furthermore, if the control circuit 2 performs open-loop control, which attempts to rotate the motor 40 with a constant force rather than maintaining its rotational speed, the signal generation unit 22 may generate a drive control signal Sd for the motor 40 based on the specified rotational direction information Str and the specified rotational speed information Stv, without using the actual rotational speed information Sv. For example, the signal generation unit 22 may generate a PWM signal having a duty cycle pre-associated with the specified rotational speed information Stv so that the motor 40 rotates in the rotational direction specified by the specified rotational direction information Str, and output this as the drive control signal Sd.

[0080] The motor stop determination unit 24 determines whether the motor 40 is stopped or not. Specifically, the motor stop determination unit 24 monitors the rotation status signal So and determines whether the motor 40 is stopped or not based on the frequency or period of the rotation status signal So. For example, the motor stop determination unit 24 determines that the motor 40 is stopped if the frequency of the rotation status signal So is below a threshold, and determines that the motor 40 is not stopped (the motor 40 is rotating) if the frequency of the rotation status signal So is greater than the threshold. The threshold can be set to an appropriate value depending on the application to which the fan unit 6 is applied. For example, the threshold is 10 Hz.

[0081] Figure 4 is a flowchart showing an example of the processing flow by the motor drive control device 1 according to Embodiment 1.

[0082] For example, when a DC voltage Vdc is applied to the fan unit 6, the control circuit 2 is activated. The control circuit 2 determines, for example, whether the motor 40 has stopped after a predetermined period (sleep mode) has elapsed (step S11). Specifically, the motor stop determination unit 24 determines whether the motor 40 has stopped based on the frequency (or period) of the rotation status signal So using the method described above.

[0083] If the control circuit 2 determines that the motor 40 is stopped (step S11: YES), the output control unit 26 stops outputting the rotation status signal So (step S12). As a result, the signal input / output terminal P4 functions as an input terminal.

[0084] Next, the control circuit 2 identifies the specified rotation direction based on the rotation direction specification signal S1 input to the signal input / output terminal P4 (step S13). Specifically, the drive command analysis unit 21 identifies the specified rotation direction based on the characteristics (voltage, frequency, duty cycle, etc.) of the rotation direction specification signal S1 input to the signal input / output terminal P4 using the method described above, and provides the specified rotation direction information Str to the signal generation unit 22. For example, if the signal input / output terminal P4 is pulled up as in the example above, the pull-up voltage (5V or 12V) is input to the signal input / output terminal P4 as the rotation direction specification signal S1. For example, the host device 7 sets the pull-up voltage to "5V (or 12V)" when specifying "forward direction" as the rotation direction, and sets the pull-up voltage to "0V" when specifying "reverse direction" as the rotation direction. The drive command analysis unit 21 then identifies the specified rotation direction by determining the voltage level of the rotation direction specification signal S1.

[0085] Next, the control circuit 2 determines whether or not the rotation speed specification signal S2 has been input (step S14). If the rotation speed specification signal S2 has not been input (step S14: NO), the control circuit 2 returns to step S13 and determines the direction of rotation based on the rotation direction specification signal S1.

[0086] On the other hand, if a rotational speed specification signal S2 is input (step S14: YES), the control circuit 2 identifies the specified rotational speed (target rotational speed) (step S15). Specifically, the drive command analysis unit 21 identifies the specified target rotational speed based on the duty cycle of the rotational speed specification signal S2 input to the signal input terminal P3 using the method described above, and provides the specified rotational speed information Stv to the signal generation unit 22.

[0087] After step S14, the control circuit 2 generates a drive control signal Sd (step S16). Specifically, the signal generation unit 22 generates a PWM signal as the drive control signal Sd using the method described above, based on the specified rotation direction information Str acquired in step S13 and the specified rotation speed information Stv acquired in step S15, and provides it to the drive circuit 3. As a result, the motor 40 rotates. The control circuit 2 generates a rotation state signal So according to the rotation of the motor 40 (step S17). Next, the control circuit 2 outputs the rotation state signal So from the signal input / output terminal P4 via the output control unit 26 (step S18). As a result, the signal input / output terminal P4 functions as an output terminal.

[0088] Furthermore, in step S11, if the control circuit 2 determines that the motor 40 is not stopped (step S11: NO), the output control unit 26 continues to output the rotation status signal So from the signal input / output terminal P4 (step S18). As a result, the signal input / output terminal P4 continues to function as an output terminal.

[0089] Figure 5 shows an example of the relationship between the drive command signal Sc (rotation direction specification signal S1 and rotation speed specification signal S2) and the operating state of the fan 4 in the fan unit 6 according to Embodiment 1.

[0090] Figure 5 shows the waveforms of the DC voltage Vdc, the voltage at the signal input terminal P3 (rotation speed specification signal S2), the voltage at the signal input / output terminal P4 (rotation direction specification signal S1 / rotation status signal So), and the rotation speed, from top to bottom. In the example in Figure 5, it is assumed that the rotation direction specification signal S1 and the rotation status signal So are 5V or 0V.

[0091] As shown in Figure 5, for example, at time t0, a DC voltage Vdc is input and the fan unit 6 starts up. At this time, a voltage of 5V is input to the signal input / output terminal P4 from the host device 7.

[0092] For example, after startup, the control circuit 2 enters a sleep mode in which it does not accept external signal inputs, resets internal registers, etc., and sets initial values ​​for the registers, etc. After a predetermined period of time has elapsed, the control circuit 2 exits sleep mode and transitions to normal mode in which it drives the motor 40 according to the drive command signal Sc. For example, at time t1 shown in Figure 5, the control circuit 2 transitions from sleep mode to normal mode.

[0093] At this time, since the motor 40 is stopped, the control circuit 2 stops the output of the rotation state signal So from the signal input / output terminal P4 by the output control unit 26, recognizes the signal input to the signal input / output terminal P4 as the rotation direction specification signal S1, and identifies the specified rotation direction using the method described above. In the example shown in Figure 5, since the voltage at the signal input / output terminal P4 at time t1 is "5V", the control circuit 2 determines that "forward direction (positive rotation)" is specified.

[0094] Next, the control circuit 2 analyzes the duty cycle of the rotation speed specification signal S2 input to the signal input terminal P3 to determine the specified rotation speed. Then, the control circuit 2 generates a drive control signal Sd so that the motor 40 rotates in the forward direction at the specified rotation speed, causing the motor 40 to rotate in the forward direction. As a result, a rotation status signal So is generated, and the control circuit 2, via the output control unit 26, enables the output of the rotation status signal So from the signal input / output terminal P4. Consequently, a pulse representing the rotation status signal So is output from the signal input / output terminal P4 from time t1 onward.

[0095] Subsequently, at time t2, the rotation speed specification signal S2 is fixed at a low level, causing the control circuit 2 to stop rotating the motor 40. As a result, the motor 40 rotates by inertia and stops at time t3. At time t4, after a predetermined period Txs has elapsed since detecting the motor 40 stopping, the control circuit 2 recognizes the signal input to the signal input / output terminal P4 as the rotation direction specification signal S1 and identifies the specified rotation direction using the method described above. In the example shown in Figure 5, since the voltage at the signal input / output terminal P4 at time t4 is "0V", the control circuit 2 determines that "reverse direction (negative rotation)" is specified.

[0096] Next, the control circuit 2 analyzes the duty cycle of the rotation speed specification signal S2 input to the signal input terminal P3 at time t5 and identifies the specified rotation speed. Then, it generates a drive control signal Sd so that the motor 40 rotates in the reverse direction (negative rotation) at the specified rotation speed, causing the motor 40 to rotate negatively. As a result, a rotation status signal So is generated, and the control circuit 2 enables the output of the rotation status signal So from the signal input / output terminal P4 via the output control unit 26. Consequently, a pulse representing the rotation status signal So is output from the signal input / output terminal P4 from time t5 onward.

[0097] Subsequently, at time t6, the rotation speed specification signal S2 is fixed at a low level, causing the control circuit 2 to stop rotating the motor 40. As a result, the motor 40 rotates by inertia and stops at time t7. From the time the motor 40 stops until a predetermined period Txs has elapsed, the control circuit 2 does not recognize the signal input to the signal input / output terminal P4 as the rotation direction specification signal S1 and does not analyze the rotation direction specification signal S1. As shown in Figure 5, when the input of the rotation speed specification signal S2 is resumed at time t8, after a period Tys (≤ Txs) has elapsed from time t7, the control circuit 2 generates a drive control signal Sd to rotate in the rotation direction previously specified, i.e., the "reverse direction (negative rotation)", and drives the motor 40. Note that the timing to start measuring the predetermined period Txs may be time t2, when the rotation speed specification signal S2 is fixed at a low level.

[0098] In the fan unit 6 according to Embodiment 1 described above, the control circuit 2 stops outputting the rotation status signal So from the signal input / output terminal P4 when it detects that the motor 40 is stopped, and outputs the rotation status signal So from the signal input / output terminal P4 when it detects that the motor 40 is not stopped.

[0099] According to this, the signal input / output terminal P4 can be switched between an input terminal and an output terminal depending on whether the motor 40 is stopped or not. Therefore, when the signal input / output terminal P4 is functioning as an input terminal, the rotation direction of the motor 40 can be specified by inputting the rotation direction specification signal S1 to the signal input / output terminal P4. On the other hand, when the signal input / output terminal P4 is functioning as an output terminal, the rotation status signal So can be output from the signal input / output terminal P4 as before.

[0100] As described above, with the fan unit 6 (motor drive control device 1) according to Embodiment 1, the rotation direction of the motor 40 can be specified by the signal input to the signal input / output terminal P4, so that the target rotation speed can be assigned to the entire range of the duty cycle of the rotation speed specification signal S2 (PWM signal) input to the signal input terminal P3. This makes it possible to switch the rotation direction of the motor 40 while ensuring a wide range of setting the rotation speed of the motor 40.

[0101] Furthermore, in the motor drive control device 1, the control circuit 2 determines that the motor 40 is not stopped if the frequency of the rotation status signal So is above a threshold, and determines that the motor 40 is stopped if the frequency of the rotation status signal So is below the threshold. This makes it possible to easily detect whether the motor 40 is stopped or not.

[0102] Furthermore, in the motor drive control device 1, the control circuit 2 analyzes the rotation direction specification signal S1 after a predetermined period Txs has elapsed since determining that the motor 40 is stopped. This makes it possible to prevent the rotation direction of the motor 40 from being unintentionally switched when the motor 40 is stopped for a short time for any reason.

[0103] Furthermore, in the motor drive control device 1, the control circuit 2 determines that the first direction (forward direction) is specified as the direction of rotation when the rotation direction specification signal S1 satisfies the first condition, and determines that the second direction (reverse direction) is specified as the direction of rotation when the rotation direction specification signal S1 satisfies the second condition. According to this, the rotation direction of the motor 40 can be easily changed by changing the characteristics of the rotation direction specification signal S1.

[0104] <Embodiment 2> Figure 6 is a diagram showing the configuration of a fan system 100A equipped with a fan unit 6A according to Embodiment 2. Figure 7 is a block diagram showing the configuration of the fan unit 6A according to Embodiment 2.

[0105] The fan unit 6A according to Embodiment 2 differs from the fan unit 6 according to Embodiment 1 in that it specifies a designated rotation direction based on the magnitude of the high level of the rotation state signal So output from the signal input / output terminal P4 which is pulled up to a predetermined voltage, but is otherwise the same as the fan unit 6 according to Embodiment 1.

[0106] The signal input / output terminal P4 is pulled up to a predetermined voltage. For example, the signal input / output terminal P4 is pulled up to a voltage generated by the host device A7.

[0107] As shown in Figure 6, the host device 7A includes a control circuit 71, a voltage generation circuit 72, and a pull-up resistor Rpu.

[0108] The control circuit 71 is the main circuit for realizing the functions of the higher-level device 7A, and is, for example, a program processing unit including a processor and memory. The control circuit 71 comprehensively controls other circuits within the higher-level device 7A in order to realize the functions of the higher-level device 7A.

[0109] For example, when the control circuit 71 specifies the rotation speed of the fan 4 (motor 40), it generates a rotation speed specification signal S2 containing information about the specified rotation speed and outputs it from the external terminal Po. Also, when the control circuit 71 specifies the rotation direction of the fan 4 (motor 40), it specifies the magnitude of the voltage to be output to the voltage generation circuit 72. For example, when specifying a first direction (forward rotation) as the rotation direction of the motor 40, the control circuit 71 instructs the voltage generation circuit 72 to generate a first voltage (e.g., 5V) as the voltage Vout, which is smaller than the threshold Vth described later. When specifying a second direction (reverse rotation) as the rotation direction of the motor 40, the control circuit 71 instructs the voltage generation circuit 72 to generate a second voltage (e.g., 12V) as the voltage Vout, which is larger than the threshold Vth. Furthermore, the control circuit 71 monitors the rotation state of the motor 40 based on the frequency (period) of the rotation state signal So input from the external terminal Pio.

[0110] The voltage generation circuit 72 is a circuit that generates and outputs a voltage of a predetermined magnitude (hereinafter also referred to as "output voltage") Vout. The voltage generation circuit 72 is, for example, a regulator that generates a constant voltage such as an AC / DC converter or a DC / DC converter.

[0111] The voltage generation circuit 72 generates and outputs a predetermined voltage in response to instructions from the control circuit 71. As described above, when the control circuit 71 instructs the voltage generation circuit 72 to generate a first voltage (5V), the voltage generation circuit 72 generates a first voltage (5V) and outputs it as the output voltage Vout. Similarly, when the control circuit 71 instructs the voltage generation circuit 72 to generate a second voltage (12V), the voltage generation circuit 72 generates a second voltage (12V) and outputs it as the output voltage Vout.

[0112] The voltage Vout output from the voltage generation circuit 72 is supplied to the power line Vcc as a power supply voltage to other circuits in the control circuit 71, for example.

[0113] The pull-up resistor Rpu is a resistor that pulls up the external terminal Pio. The pull-up resistor Rpu is connected between the power supply line Vcc, which supplies the output voltage Vout, and the external terminal Pio.

[0114] In the motor drive control device 1A according to Embodiment 2, the signal input / output terminal P4 is an open terminal. For example, the signal input / output terminal P4 is an open drain terminal. As described above, the signal input / output terminal P4 is pulled up to the output voltage Vout via a pull-up resistor Rpu which acts as a load.

[0115] The control circuit 2A determines the specified rotation direction and generates a drive control signal Sd based on the magnitude of the high-level voltage of the first signal appearing at the signal input / output terminal P4. Specifically, the control circuit 2A includes a rotation state signal generation unit 25A and a drive control signal generation unit 20A.

[0116] The rotation state signal generation unit 25A, similar to the rotation state signal generation unit 25, detects the rotation state of the motor 40, generates a binary signal according to the detected rotation state, and outputs it as a rotation state signal So. Specifically, the rotation state signal generation unit 25A generates the rotation state signal So by driving a load (pull-up resistor Rpu) connected to the signal input / output terminal P4. As shown in Figure 7, for example, if a transistor M1 (e.g., an FET) is provided connected between the signal input / output terminal P4 and ground potential, the rotation state signal generation unit 25A switches the on / off state of the transistor M1 in synchronization with the rotation position detection signal Sh. As a result, a rotation state signal So, whose voltage level switches between high and low levels, is output from the signal input / output terminal P4. Note that the rotation state signal generation unit 25A may drive the signal input / output terminal P4 even without providing the transistor M1.

[0117] Here, the low level of the rotation status signal So is, for example, the ground voltage (0V). The high level of the rotation status signal So is the pull-up voltage, that is, the voltage corresponding to the output voltage Vout of the power line Vcc of the higher-level device 7A. For example, if the output voltage Vout is 5V, the high level of the rotation status signal So will be 5V, and if the output voltage Vout is 12V, the high level of the rotation status signal So will be 12V.

[0118] The drive control signal generation unit 20A generates a drive control signal Sd. Specifically, the drive control signal generation unit 20A includes a drive command analysis unit 21A, a signal generation unit 22, and a rotational speed calculation unit 23.

[0119] The drive command analysis unit 21A analyzes the first signal appearing at the signal input / output terminal P4 to identify the specified rotation direction and generates information on the specified rotation direction. It also analyzes the rotation speed specification signal S2, which is the second signal appearing at the signal input terminal P3, to identify the specified rotation speed and generates information on the specified rotation speed. Specifically, the drive command analysis unit 21A analyzes the rotation speed specification signal S2 using the same method as the drive command analysis unit 21 to identify the specified rotation speed, and generates and outputs the specified rotation speed information Stv.

[0120] Here, if the motor 40 is rotating, the rotation status signal So becomes the first signal. On the other hand, if the motor 40 is not rotating, a constant voltage appearing at the signal input / output terminal P4 becomes the first signal.

[0121] The drive command analysis unit 21A determines the specified direction of rotation based on the magnitude of the high level of the first signal. For example, when the motor 40 is rotating, the drive command analysis unit 21A determines that the first direction (forward rotation) is specified as the direction of rotation if the high level of the rotation state signal So is greater than the threshold Vth, and determines that the second direction (negative rotation), opposite to the first direction, is specified as the direction of rotation if the high level of the rotation state signal So is less than the threshold Vth. Also, when the motor 40 is not rotating, the drive command analysis unit 21A determines that the first direction (forward rotation) is specified as the direction of rotation if a constant voltage (pull-up voltage) appearing at the signal input / output terminal P4 is greater than the threshold Vth, and determines that the second direction (negative rotation), opposite to the first direction, is specified as the direction of rotation if the constant voltage (pull-up voltage) appearing at the signal input / output terminal P4 is less than the threshold Vth. The drive command analysis unit 21A determines the specified direction of rotation using the method described above, generates specified direction of rotation information Str, and outputs it.

[0122] Here, the threshold Vth is a reference value for determining the magnitude of the pull-up voltage of the higher-level device 7A, i.e., the output voltage Vout generated by the voltage generation circuit 72. For example, the threshold Vth is set to a value greater than the first voltage (5V) and less than the second voltage (12V).

[0123] For example, if the voltage at the signal input / output terminal P4 remains greater than the threshold Vth for a predetermined period of time, the drive command analysis unit 21A may determine that the high-level voltage of the rotation state signal So (first signal) has switched from the first voltage to the second voltage. Similarly, if the voltage at the signal input / output terminal P4 remains less than the threshold Vth for a predetermined period of time, the drive command analysis unit 21A may determine that the high-level voltage of the rotation state signal So (first signal) has switched from the second voltage to the first voltage.

[0124] Figure 8 is a flowchart showing an example of the processing flow by the motor drive control device 1A according to Embodiment 2.

[0125] For example, when a DC voltage Vdc is applied to the fan unit 6A, the control circuit 2A is activated. The control circuit 2A then determines a specified rotation direction based on the high level (pull-up voltage) of the first signal that appears at the signal input / output terminal P4, for example, after a predetermined period (sleep mode) has elapsed (step S13A).

[0126] For example, immediately after the fan unit 6A is powered on, the motor 40 is not rotating, so the rotation status signal So is not output, and the voltage appearing at the signal input / output terminal P4 remains constant at a high level. That is, the voltage appearing at the signal input / output terminal P4 is the output voltage Vout output from the voltage generation circuit 72 of the higher-level device 7A. At this time, if the higher-level device 7A (control circuit 71) instructs the motor 40 to rotate in the forward direction, a first voltage (5V) is output as the output voltage Vout, and if it instructs the motor 40 to rotate in the reverse direction, a second voltage (12V) is output as the output voltage Vout.

[0127] The drive command analysis unit 21A identifies the specified rotation direction by comparing the high level of the first signal (the high-level voltage of the rotation state signal So or a constant voltage appearing at the signal input / output terminal P4) with the threshold Vth using the method described above, and provides the specified rotation direction information Str to the signal generation unit 22. The subsequent processing flow (S14 to S18) is the same as the processing flow of the motor drive control device 1 according to Embodiment 1.

[0128] On the other hand, when the motor 40 is rotating, a binary signal having a frequency corresponding to the rotation speed of the motor 40 is output from the signal input / output terminal P4 as the rotation status signal So. In this case as well, just as immediately after the fan unit 6A is powered on, the drive command analysis unit 21A identifies the specified rotation direction by comparing the high-level voltage of the rotation status signal So with the threshold value Vth.

[0129] Figure 9 shows an example of the relationship between the drive command signal Sc (rotation state signal So and rotation speed specification signal S2) and the operating state of the fan 4 in the fan unit 6A according to Embodiment 2.

[0130] Figure 9 shows the waveforms of the DC voltage Vdc, the voltage at the signal input terminal P3 (rotation speed specification signal S2), the voltage at the signal input / output terminal P4 (rotation status signal So), and the rotation speed, from top to bottom.

[0131] As shown in Figure 9, for example, at time t0 when the motor 40 is stopped, a DC voltage Vdc is input. This starts the fan unit 6.

[0132] Meanwhile, in the higher-level device 7A, the control circuit 71 instructs the voltage generation circuit 72 to generate an output voltage Vout of 5V (first voltage) in order to specify the first direction (forward rotation) as the rotation direction of the motor 40. At this time, since the motor 40 is stopped, the rotation state signal generation unit 25A of the control circuit 2A of the fan unit 6 turns off the transistor M1. As a result, the voltage at the signal input / output terminal P4 is kept constant at the output voltage Vout (= 5V) by the pull-up resistor Rpu.

[0133] The control circuit 2A of the fan unit 6 determines the specified rotation direction based on the high level of the first signal that appears at the signal input / output terminal P4. In the example shown in Figure 9, since the voltage at the signal input / output terminal P4 at time t1 is "5V", the control circuit 2A determines that "forward direction (forward rotation)" is specified.

[0134] Next, the control circuit 2A analyzes the duty cycle of the rotation speed specification signal S2 input to the signal input terminal P3 to determine the specified rotation speed. Then, the control circuit 2A generates a drive control signal Sd so that the motor 40 rotates in the forward direction at the specified rotation speed, causing the motor 40 to rotate in the forward direction. As a result, a rotation status signal So is generated, and the control circuit 2A enables the rotation status signal So to be output from the signal input / output terminal P4 by the rotation status signal generation unit 25A. Consequently, a pulse as the rotation status signal So is output from the signal input / output terminal P4 from time t1 onward.

[0135] Subsequently, at time t2, the rotation speed specification signal S2 is fixed at a low level, causing the control circuit 2A to stop rotating the motor 40. As a result, the motor 40 rotates by inertia and stops at time t3. At this time, the voltage at the signal input / output terminal P4 is constant at the output voltage Vout (= 5V) due to the pull-down resistor Rpu.

[0136] At time t4, the control circuit 71 of the higher-level device 7A instructs the voltage generation circuit 72 to generate an output voltage Vout of 12V (second voltage) in order to specify the second direction (negative rotation) as the rotation direction of the motor 40. At this time, since the motor 40 is stopped, the rotation status signal generation unit 25A of the control circuit 2A on the fan unit 6 side turns off the transistor M1. As a result, the voltage at the signal input / output terminal P4 becomes the output voltage Vout (=12V) due to the pull-up resistor Rpu.

[0137] The control circuit 2A of the fan unit 6 determines the specified rotation direction based on the high level of the first signal that appears at the signal input / output terminal P4. In the example shown in Figure 9, at time t5, a certain period of time has elapsed from time t4 when the voltage at the signal input / output terminal P4 switched, the control circuit 2A determines that the high-level voltage appearing at the signal input / output terminal P4 has switched from "5V" to "12V", and determines that "reverse direction (negative rotation)" is specified. Note that the timing to start measuring the above certain period may be time t2 when the rotation speed specification signal S2 is fixed at a low level.

[0138] Next, the control circuit 2A analyzes the duty cycle of the rotation speed specification signal S2 input to the signal input terminal P3 at time t6 and determines the specified rotation speed. Then, it generates a drive control signal Sd so that the motor 40 rotates in the reverse direction (negative rotation) at the specified rotation speed, causing the motor 40 to rotate negatively. As a result, from time t5 onward, a high-level pulse of 12V is output from the signal input / output terminal P4 as the rotation status signal So.

[0139] In the fan unit 6A according to Embodiment 2 described above, the signal input / output terminal P4 is an open terminal and is pulled up to a predetermined voltage (first voltage or second voltage) via a pull-down resistor Rpu as a load. The control circuit 2A determines the specified rotation direction based on the magnitude of the high-level voltage of the first signal appearing at the signal input / output terminal P4.

[0140] According to this, the rotation direction of the motor 40 can be specified by the magnitude of the pull-up voltage (output voltage Vout) of the signal input / output terminal P4, so that the target rotation speed can be assigned to the entire range of the duty cycle of the rotation speed specification signal S2 (PWM signal) input to the signal input terminal P3. This makes it possible to switch the rotation direction of the motor 40 while ensuring a wide range of setting the rotation speed of the motor 40.

[0141] Furthermore, this allows the signal input / output terminal P4 of the fan unit 6 to be used as a terminal to output the rotation status signal So, similar to conventional fan units, thus reducing the effort required to redesign the microcontroller as the control circuit 2A.

[0142] Furthermore, in the fan unit 6A according to Embodiment 2, the control circuit 2A (drive command analysis unit 21A) determines that the first direction (forward direction) is specified as the rotation direction when the high level of the first signal appearing at the signal input / output terminal P4 is greater than the threshold Vth, and determines that the second direction (reverse direction), opposite to the first direction, is specified as the rotation direction when the high level of the first signal appearing at the signal input / output terminal P4 is less than the threshold Vth. With this, the rotation direction can be specified simply by switching the magnitude of the pull-up voltage based on the threshold Vth, which simplifies the design of the microcontroller as the control circuit 2A.

[0143] Note that Figure 9 illustrates a case where the higher-level device 7 switches the pull-up voltage (output voltage Vout) of the signal input / output terminal P4 after the motor 40 has stopped, but it is not limited to this. For example, as shown in Figure 10, the higher-level device 7 may switch the pull-up voltage (output voltage Vout) of the signal input / output terminal P4 while the motor 40 is rotating. In this case as well, the rotation direction of the motor 40 can be switched.

[0144] <<Expansion of Embodiments>> The present invention has been described in detail above based on embodiments, but it goes without saying that the present invention is not limited thereto and can be modified in various ways without departing from its essence.

[0145] For example, in Embodiment 1, monitoring the rotational state signal So was given as an example of a method for determining whether the motor 40 is stopped, but the method is not limited to this. For example, the motor stop determination unit 24 may monitor the rotational position detection signal Sh or the actual rotational speed information Sv and determine that the motor 40 is stopped if the actual rotational speed of the motor 40 is below a threshold. Alternatively, the motor stop determination unit 24 may monitor the rotational speed specification signal S2 and determine that the motor 40 is stopped if the rotational speed specification signal S2 remains fixed at a high level or low level for a predetermined period of time or longer. Thus, the method for determining whether the motor 40 is stopped is not limited to the above examples, and various methods can be employed.

[0146] Furthermore, while embodiments 1 and 2 illustrate the case where the motor 40 is a three-phase brushless motor, the type of motor 40, the number of phases, etc., are not limited thereto. For example, it may be a single-phase brushless motor.

[0147] Furthermore, the flowchart described above is merely an example illustrating the operation and is not limited to it. In other words, the steps shown in each diagram of the flowchart are specific examples and are not limited to this flow. For example, the order of some processes may be changed, other processes may be inserted between each process, or some processes may be performed in parallel.

[0148] 1, 1A...Motor drive control device, 2, 2A...Control circuit, 3...Drive circuit, 4...Fan, 5...Position detector, 6, 6A...Fan unit, 7, 7A...Host device, 20, 20A...Drive control signal generation unit, 21, 21A...Drive command analysis unit, 22...Signal generation unit, 23...Rotation speed calculation unit, 24...Motor stop determination unit, 25, 25A...Rotation state signal generation unit, 26...Output control unit, 40...Motor, 41...Impeller, 49-52...Signal line, 10 0...Fan system, Np...Node, P1...Power terminal, P2...Ground terminal, P3...Signal input terminal, P4...Signal input / output terminal, S1...Rotation direction specification signal (first signal), S2...Rotation speed specification signal (second signal), Sc...Drive command signal, Sd...Drive control signal, So...Rotation status signal (first signal), Stv...Specified rotation speed information, Str...Specified rotation direction information, Sv...Actual rotation speed information, Sh...Rotation position detection signal, Txs...Determined period.

Claims

1. A motor drive control device comprising: a signal input terminal; a signal input / output terminal; a control circuit that generates a drive control signal for controlling the rotation of the motor so that the motor rotates in a rotation direction specified by a first signal appearing at the signal input / output terminal and at a rotation speed specified by a second signal appearing at the signal input terminal, and also generates a rotation state signal indicating the rotation state of the motor; and a drive circuit that drives the motor based on the drive control signal.

2. A motor drive control device according to claim 1, wherein the control circuit stops outputting the rotation status signal from the signal input / output terminal when it detects that the motor is stopped, and outputs the rotation status signal from the signal input / output terminal when it detects that the motor is not stopped.

3. A motor drive control device according to claim 2, wherein the control circuit includes: a rotation state signal generation unit that detects the rotation state of the motor and generates and outputs the rotation state signal; an output control unit that switches whether or not to output the rotation state signal from the signal input / output terminal; a drive control signal generation unit that determines whether or not the motor is rotating based on the rotation state signal and generates the drive control signal, wherein the drive control signal generation unit includes: a drive command analysis unit that analyzes the first signal to identify a specified rotation direction and generates information for the specified rotation direction, analyzes the second signal to identify a specified rotation speed and generates information for the specified rotation speed; a signal generation unit that generates the drive control signal based on the information for the specified rotation direction and the information for the specified rotation speed; and a motor stop determination unit that determines whether or not the motor is stopped, wherein the output control unit stops outputting the rotation state signal from the signal input / output terminal when the motor stop determination unit determines that the motor is stopped, and outputs the rotation state signal from the signal input / output terminal when the motor stop determination unit determines that the motor is not stopped.

4. A motor drive control device according to claim 3, wherein the rotation status signal is a signal having a frequency corresponding to the actual rotation speed of the motor, and the motor stop determination unit determines that the motor is not stopped when the frequency of the rotation status signal is equal to or greater than a threshold, and determines that the motor is stopped when the frequency of the rotation status signal is lower than the threshold.

5. A motor drive control device according to claim 4, wherein the drive command analysis unit analyzes the first signal after a predetermined period has elapsed since the motor stop determination unit determined that the motor was stopped.

6. A motor drive control device according to claim 3, wherein the drive command analysis unit determines that a first direction is designated as the rotation direction when the first signal satisfies a first condition, and determines that a second direction opposite to the first direction is designated as the rotation direction when the first signal satisfies a second condition different from the first condition.

7. A motor drive control device according to claim 1, wherein the signal input / output terminal is an open terminal and is pulled up to a predetermined voltage via a load, the high level of the first signal is a voltage corresponding to the predetermined voltage, and the control circuit determines the specified rotation direction based on the magnitude of the high-level voltage of the first signal.

8. A motor drive control device according to claim 7, wherein the predetermined voltage is a first voltage or a second voltage greater than the first voltage.

9. A motor drive control device according to claim 7, wherein the control circuit includes: a rotation state signal generation unit that detects the rotation state of the motor and generates the rotation state signal by driving the load connected to the signal input / output terminal according to the detected rotation state; and a drive control signal generation unit that generates the drive control signal, wherein the drive control signal generation unit includes: a drive command analysis unit that analyzes the first signal appearing at the signal input / output terminal to identify a specified rotation direction and generates information on the specified rotation direction, and analyzes the second signal to identify a specified rotation speed and generates information on the specified rotation speed; and a signal generation unit that generates the drive control signal based on the information on the specified rotation direction and the information on the specified rotation speed, wherein the drive command analysis unit determines that a first direction is specified as the rotation direction when the high level of the first signal appearing at the signal input / output terminal is greater than a threshold, and determines that a second direction opposite to the first direction is specified as the rotation direction when the high level of the first signal appearing at the signal input / output terminal is less than the threshold.

10. A fan unit comprising the motor, an impeller connected to the output shaft of the motor, and a motor drive control device according to any one of claims 1 to 9.

11. A motor drive control method for controlling the rotation of a motor using a motor drive control device having a signal input terminal and a signal input / output terminal, comprising: a first step of identifying a specified rotation direction based on a first signal appearing at the signal input / output terminal; a second step of identifying a specified rotation speed based on a second signal appearing at the signal input terminal; and a third step of generating a drive control signal for controlling the rotation of the motor so that the motor rotates in the rotation direction identified in the first step and at the rotation speed identified in the second step.

Images