Motor disconnection detection device and motor control device

Abstract

To provide a motor disconnection detection device capable of suppressing erroneous detection of disconnection in an operation region where a drive current of a motor is relatively small, and a motor control device.SOLUTION: A motor disconnection detection device includes a processing unit that detects disconnection of a motor connection line connecting an output end of a motor drive circuit and an input end of a motor based on a drive current supplied from the motor drive circuit to the motor via the motor connection line, and the processing unit disables disconnection detection processing only during a period from when the drive current starts to be supplied to when the drive current reaches a predetermined threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor disconnection detection device and a motor control device. [Background technology]

[0002] Patent Document 1 listed below discloses a wire break detection technology that can deal with momentary wire breaks and reliably detects wire breaks in a motor. This wire break detection technology controls the drive of a three-phase motor using a PWM inverter circuit and operates using the rotational driving force generated by the three-phase motor. The technology includes current detection means that individually detects the phase currents of the three-phase motor, and wire break determination means that determines wire breakage in each phase winding of the three-phase motor. The wire break determination means determines wire breakage when the current value detected by the current detection means for each phase remains below a threshold value for a predetermined period of time at a timing when the line voltage between each phase of the three-phase motor is above a reference value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-213666 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while the background art detects a wire break in a three-phase motor based on the phase current of the motor, such wire break detection based on the phase current may erroneously detect a wire break in an operating region where the phase current (drive current) of the motor is relatively small. The background art does not provide any insight into such erroneous detection.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a motor disconnection detection device and a motor control device that can suppress erroneous detection of disconnection in operating regions where the motor drive current is relatively small. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides, as a first solution relating to a motor disconnection detection device, a motor disconnection detection device that includes a processing unit that detects a disconnection in a motor connection line connecting the output terminal of a motor drive circuit and the input terminal of a motor based on the drive current supplied from the motor drive circuit to the motor via the motor connection line, and the processing unit employs a means for disabling the disconnection detection process for the period from the start of power supply until the drive current reaches a predetermined threshold value.

[0007] The present invention employs, as a second solution relating to a motor disconnection detection device, a solution in the first solution described above, in which the motor drive circuit supplies the drive current to the motor based on a PWM signal, and the processing unit sets the period based on the duty ratio of the PWM signal.

[0008] The present invention employs a solution relating to a motor control device, in which the motor control device is provided with any one of the first to third motor disconnection detection devices. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a motor disconnection detection device and a motor control device that are capable of suppressing erroneous detection of a disconnection in an operating region where the motor drive current is relatively small. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a circuit diagram showing the configuration of a motor control device (motor disconnection detection device) according to one embodiment of the present invention. [Figure 2] 3 is a flowchart showing the operation of a motor control device (motor disconnection detection device) according to one embodiment of the present invention. [Figure 3] 4 is a timing chart showing the operation of a motor control device (motor disconnection detection device) according to one embodiment of the present invention. [Figure 4]1 is a schematic diagram illustrating the operation of a motor control device (motor disconnection detection device) according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1, the power generating device A in this embodiment includes a motor control device 1, a motor drive circuit 2, a motor 3, a current sensor 4, and a pair of motor connection lines H1 and H2. The motor control device 1 is a software control device that controls the motor 3 via the motor drive circuit 2.

[0012] That is, the motor control device 1 generates four control signals a1 to a4 based on a pre-stored control program (motor control program) and outputs them to the motor drive circuit 2. The motor control device 1 has at least one input terminal and four output terminals. One of the input terminals of the motor control device 1 is connected to the output terminal of the current sensor 4, and a current detection signal b is input from the current sensor 4.

[0013] The four output terminals of the motor control device 1 are connected to the motor drive circuit 2. Of the four output terminals, a first output terminal outputs a first control signal a1 to a first switching transistor SW1 in the motor drive circuit 2, as shown in the figure. Furthermore, a second output terminal of the motor control device 1 outputs a second control signal a2 to a second switching transistor SW2 in the motor drive circuit 2, as shown in the figure.

[0014] As shown, the third output terminal of the motor control device 1 outputs a third control signal a3 to the third switching transistor SW3 in the motor drive circuit 2. As shown, the fourth output terminal of the motor control device 1 outputs a fourth control signal a4 to the fourth switching transistor SW4 in the motor drive circuit 2.

[0015] The motor control device 1 outputs these four control signals a1 to a4 to the motor drive circuit 2 to control the drive current, i.e., the motor current, supplied from the motor drive circuit 2 to the motor 3. By manipulating the motor current, the motor control device 1 controls the rotation of the motor 3, i.e., the rotation direction (forward / reverse) and number of rotations (rotational speed).

[0016] The four control signals a1 to a4 are, for example, PWM (Pulse Width Modulation) signals. That is, the four control signals a1 to a4 are control signals that control the motor current based on a duty ratio, which is the ratio between an H (high) level period and an L (low) level period.

[0017] Here, the motor control device 1 has a control function (main function) of generating four control signals a1 to a4 based on a motor control program, as well as a disconnection detection function (secondary function) of detecting a disconnection in a pair of motor connection lines H1, H2 based on a drive current detection signal b.

[0018] That is, the motor control device 1 has a wire break detection function that detects a wire break in a pair of motor connection lines H1, H2 that connect the output terminals Tout1, Tout2 of the motor drive circuit 2 to the input terminals Tin1, Tin2 of the motor 3, based on the drive current Id supplied to the motor 3 from the motor drive circuit 2 via the motor connection lines H1, H2. Such a motor control device 1 corresponds to the motor wire break detection device according to the present invention, and also corresponds to the processing unit in the present invention.

[0019] The motor drive circuit 2 is a type of power amplifier circuit that generates a motor current based on four control signals a1 to a4 input from the motor control device 1 and outputs the generated motor current to the motor 3. As shown in the figure, the motor drive circuit 2 includes, for example, four switching transistors SW1 to SW4. As shown in the figure, the four switching transistors SW1 to SW4 are, for example, IGBTs (Insulated Gate Bipolar Transistors).

[0020] As shown in the figure, of the four switching transistors SW1 to SW4, the first switching transistor SW1 and the second switching transistor SW2 are connected in series to each other to form a first switching leg, and the third switching transistor SW3 and the second switching transistor SW4 are connected in series to each other to form a second switching leg.

[0021] As shown in the figure, of the four switching transistors SW1 to SW4, the first switching transistor SW1 and the second switching transistor SW2 are connected in series to each other to form a first switching leg, and the third switching transistor SW3 and the second switching transistor SW4 are connected in series to each other to form a second switching leg.

[0022] That is, the first switching transistor SW1 has a collector terminal connected to the DC power supply Vcc, an emitter terminal connected to the collector terminal of the second switching transistor SW2, and a gate terminal connected to a first output terminal of the motor control device 1. On the other hand, the second switching transistor SW2 has a collector terminal connected to the emitter terminal of the first switching transistor SW1, an emitter terminal grounded, and a gate terminal connected to a second output terminal of the motor control device 1.

[0023] Of the first switching transistor SW1 and the second switching transistor SW2, the first switching transistor SW1 is an upper arm switching transistor in the first switching leg, and the second switching transistor SW2 is a lower arm switching transistor in the first switching leg.

[0024] The midpoint of the first switching leg, i.e., the connection point between the emitter terminal of the first switching transistor SW1 and the collector terminal of the second switching transistor SW2, is the output terminal of the first switching leg. The output terminal of the first switching leg is one of the output terminals of the motor drive circuit 2, and is connected to the first output terminal Tout1 of the motor drive circuit 2 as shown in the figure.

[0025] The third switching transistor SW3 has a collector terminal connected to the DC power supply Vcc, an emitter terminal connected to the collector terminal of the fourth switching transistor SW4, and a gate terminal connected to the third output terminal of the motor control device 1. On the other hand, the fourth switching transistor SW4 has a collector terminal connected to the emitter terminal of the third switching transistor SW3, an emitter terminal grounded, and a gate terminal connected to the fourth output terminal of the motor control device 1.

[0026] Of the third switching transistor SW3 and the fourth switching transistor SW4, the third switching transistor SW3 is an upper arm switching transistor in the second switching leg, and the fourth switching transistor SW4 is a lower arm switching transistor in the second switching leg.

[0027] The midpoint of the second switching leg, i.e., the connection point between the emitter terminal of the third switching transistor SW3 and the collector terminal of the fourth switching transistor SW4, is the other output terminal of the motor drive circuit 2. The output terminal of the second switching leg is the other output terminal of the motor drive circuit 2, and is connected to the second output terminal Tout2 of the motor drive circuit 2 as shown in the figure.

[0028] In such a motor drive circuit 2, the four switching transistors SW1 to SW4 are set to the ON state (conducting state) or the OFF state (non-conducting state) based on the four control signals a1 to a4, so that the first output terminal Tout1 and the second output terminal Tout2 are connected to the DC power supply Vcc or the ground potential (GND), or are set to a floating state.

[0029] The motor drive circuit 2 supplies a drive current Id corresponding to the connection state of the first output terminal Tout1 and the second output terminal Tout2 to the motor 3. The dashed arrow in Fig. 1 indicates the drive current Id when the first output terminal Tout1 is connected to the DC power supply Vcc and the second output terminal Tout2 is connected to the ground potential (GND).

[0030] The motor 3 is connected to the motor drive circuit 2 via a pair of motor connection lines H1, H2. That is, the motor 3 has a pair of input terminals Tin1, Tin2, with the first input terminal Tin1 connected to the first output terminal Tout1 via the first motor connection line H1. Furthermore, the second input terminal Tin2 of the motor 3 is connected to the second output terminal Tout2 via the second motor connection line H2.

[0031] The motor 3 is supplied with a drive current Id from the motor drive circuit 2 via a pair of motor connection lines H1 and H2, and is a power source that generates rotational power based on the drive current Id. For example, when the drive current Id indicated by the dashed arrow is applied, the motor 3 rotates forward at a rotation speed corresponding to the magnitude of the drive current Id, and when the drive current Id is applied in the direction opposite to the dashed arrow, the motor 3 rotates reversely at a rotation speed corresponding to the magnitude of the drive current Id.

[0032] The current sensor 4 is provided as an accessory to the motor 3 and is a current detector that detects the drive current Id flowing through the motor 3. The current sensor 4 outputs a current detection signal b indicating the magnitude of the drive current Id to the input terminal of the motor control device 1.

[0033] Next, the operation of the power generating device A in this embodiment, in particular the operation of the motor control device 1 (motor disconnection detection device), will be described with reference to FIGS.

[0034] First, we will explain the control operation (main operation) of the motor control device 1 according to this embodiment. In the power generating device A according to this embodiment, the motor control device 1 generates four control signals a1 to a4 based on a motor control program and outputs the control signals a1 to a4 to the motor drive circuit 2. That is, the motor control device 1 outputs the first control signal a1 generated based on the motor control program to the gate terminal of the first switching transistor SW1 in the motor drive circuit 2.

[0035] The motor control device 1 also outputs a second control signal a2 generated based on the motor control program to the gate terminal of the second switching transistor SW2 in the motor drive circuit 2. The motor control device 1 also outputs a third control signal a3 generated based on the motor control program to the gate terminal of the third switching transistor SW3 in the motor drive circuit 2. The motor control device 1 also outputs a fourth control signal a4 generated based on the motor control program to the gate terminal of the fourth switching transistor SW4 in the motor drive circuit 2.

[0036] In the motor drive circuit 2, the four switching transistors SW1 to SW4 are set to an ON state (conducting state) or an OFF state (non-conducting state) based on the four control signals a1 to a4. Based on the ON / OFF states of the four switching transistors SW1 to SW4, a drive current Id is passed through the motor 3 via a pair of motor connection lines H1 and H2. The motor 3h generates rotational power based on the drive current Id.

[0037] Next, the disconnection detection operation (disconnection detection processing) of the motor control device A according to this embodiment will be described with reference to the flowchart shown in Fig. 2. This disconnection detection operation, like the control operation (main operation) described above, is based on a motor control program.

[0038] As shown in the timing chart of Fig. 3, the drive current Id supplied to the motor 3 gradually increases from power supply start time t0 and is set to a predetermined value. That is, after power supply starts, the drive current Id gradually increases each time pulses constituting the four control signals a1 to a4 (PWM signals) are applied to the four switching transistors SW1 to SW4 in the motor drive circuit 2. Furthermore, as shown in Fig. 3, this increase becomes faster as the duty ratios of the four control signals a1 to a4 (PWM signals) increase.

[0039] As a disconnection detection operation, the motor control device A detects a disconnection in the pair of motor connection lines H1, H2 by comparing the drive current Id, which gradually increases after the power supply start time t0, with a predetermined current threshold Cth. That is, the motor control device A detects the magnitude of the drive current Id based on the current detection signal b input from the current sensor 4, and determines (detects) that one of the pair of motor connection lines H1, H2 is disconnected if the drive current Id is smaller than the current threshold Cth.

[0040] When the pair of motor connection lines H1, H2 are normal, the current path between one output terminal Tout1 and the other output terminal Tout2 in the motor drive circuit 2 is closed, so that the drive current Id flows normally through the motor 3.

[0041] On the other hand, if either of the pair of motor connection lines H1, H2 is broken, the current path between one output terminal Tout1 and the other output terminal Tout2 is open, and therefore the drive current Id is not supplied to the motor 3. Therefore, as described above, it is possible to determine whether either of the pair of motor connection lines H1, H2 is broken based on the comparison between the drive current Id and the current threshold value Cth.

[0042] However, as shown in Figure 3, during a period ΔR starting from power supply start time t0, drive current Id is smaller than current threshold value Cth. This period ΔR is the time from power supply start time t0 until drive current Id reaches a predetermined current threshold value Cth, and is related to the duty ratios of the four control signals a1 to a4 (PWM signals). In other words, the motor control device 1 (motor disconnection detection device) will erroneously detect a disconnection in the pair of motor connection lines H1, H2 during this period ΔR.

[0043] In response to this situation, the motor control device 1 (motor disconnection detection device) according to this embodiment disables the disconnection detection process for the pair of motor connection lines H1, H2 during the period ΔR based on the duty ratios of four control signals a1 to a4 (PWM signals), as shown in Fig. 2. In other words, the motor control device 1 sets the period ΔR as a mask period and does not perform disconnection detection for the pair of motor connection lines H1, H2.

[0044] In the disconnection detection process, the motor control device 1 first determines whether a fault has occurred in the motor 3 (step S1). If the determination in step S1 is "No," that is, if the motor control device 1 does not detect a fault in the motor 3, it performs normal processing (step S2). That is, if the motor 3 is normal, the motor control device 1 sets the status of the disconnection detection process to (0) and sets the mask period to 0 ms, as shown in FIG.

[0045] On the other hand, if the determination in step S1 is "Yes," that is, if a failure of the motor 3 is detected, the motor control device 1 determines whether the duty ratios of the four control signals a1 to a4 (PWM signals) are set to 40% or more (step S3). If the determination in step S3 is "Yes," that is, if the duty ratios are set to 40% or more, the motor control device 1 performs the normal processing described above (step S2).

[0046] On the other hand, if the determination in step S3 is "No," that is, if the duty ratio is set to a value smaller than 40%, the motor control device 1 determines whether the duty ratios of the four control signals a1 to a4 (PWM signals) are set to 30% or more (step S4).

[0047] If the determination in step S4 is "Yes," that is, if the duty ratio is set to a value less than 40% and equal to or greater than 30%, the motor control device 1 executes status update (1) (step S5). This status update (1) updates the status of the disconnection detection process to (1), as shown in Fig. 4, and sets the mask period to, for example, 3 ms.

[0048] That is, when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to a value less than 40% and greater than or equal to 30%, the mask period is set to, for example, 3 ms, so that the motor control device 1 does not perform disconnection detection when the drive current Id is smaller than the current threshold Cth. This makes it possible to avoid erroneous disconnection detection of the pair of motor connection lines H1, H2 when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to a value less than 40% and greater than or equal to 30%.

[0049] On the other hand, if the determination in step S4 is "No," that is, if the duty ratio is set to a value smaller than 30%, the motor control device 1 determines whether the duty ratios of the four control signals a1 to a4 (PWM signals) are set to 20% or more (step S6).

[0050] If the determination in step S6 is "Yes," that is, if the duty ratio is set to a value less than 30% and greater than or equal to 20%, the motor control device 1 executes status update (2) (step S7). This status update (2) updates the status of the disconnection detection process to (2), as shown in Fig. 4, and sets the mask period to, for example, 4 ms.

[0051] That is, when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to a value less than 30% and greater than or equal to 20%, the mask period is set to, for example, 4 ms, so that the motor control device 1 does not perform disconnection detection when the drive current Id is smaller than the current threshold Cth. This makes it possible to avoid erroneous disconnection detection of the pair of motor connection lines H1, H2 when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to a value less than 30% and greater than or equal to 20%.

[0052] On the other hand, if the determination in step S6 is "No," that is, if the duty ratio is set to a value smaller than 20%, the motor control device 1 determines whether the duty ratios of the four control signals a1 to a4 (PWM signals) are set to 10% or more (step S8).

[0053] If the determination in step S8 is "Yes," that is, if the duty ratio is set to a value less than 20% and greater than or equal to 10%, the motor control device 1 executes status update (3) (step S9). This status update (3) updates the status of the disconnection detection process to (3), as shown in Fig. 4, and sets the mask period to, for example, 6 ms.

[0054] That is, when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to a value less than 20% and greater than or equal to 10%, the mask period is set to, for example, 6 ms, so that the motor control device 1 does not perform disconnection detection when the drive current Id is smaller than the current threshold Cth. This makes it possible to avoid erroneous disconnection detection of the pair of motor connection lines H1, H2 when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to a value less than 20% and greater than or equal to 10%.

[0055] On the other hand, if the determination in step S8 is "No," that is, if the duty ratio is set to a value smaller than 10%, the motor control device 1 determines whether the duty ratios of the four control signals a1 to a4 (PWM signals) are set to 0% or more (step S10).

[0056] If the determination in step S10 is "Yes," that is, if the duty ratio is set to a value less than 10% and greater than or equal to 0%, the motor control device 1 executes status update (4) (step S11). This status update (4) updates the status of the disconnection detection process to (4), and sets the mask period to ∞ (always), as shown in FIG.

[0057] That is, when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to values ​​less than 10% and greater than or equal to 0%, the mask period can be set to, for example, ∞ (always) so that the motor control device 1 does not perform disconnection detection. Therefore, it is possible to avoid erroneous disconnection detection of the pair of motor connection lines H1, H2 when the duty ratios of the four control signals a1 to a4 (PWM signals) are set to values ​​less than 10% and greater than or equal to 0%.

[0058] If the determination in step S10 is "No," that is, if the four control signals a1 to a4 (PWM signals) have not been output to the motor drive circuit 2, the motor control device 1 executes status update (5) (step S12). This status update (5) updates and sets the status of the disconnection detection process to (5), as shown in Fig. 4, and determines that there is an abnormality in the pair of motor connection lines H1, H2.

[0059] The motor disconnection detection device of this embodiment includes a processing unit that detects a disconnection in a pair of motor connection lines H1, H2 connecting the output terminal of the motor drive circuit 2 and the input terminal of the motor 3 based on the drive current Id supplied from the motor drive circuit 2 to the motor 3 via the motor connection lines H1, H2, and the processing unit (motor disconnection detection device) disables the disconnection detection process for a mask period from the power supply start time t0 until the drive current Id reaches a predetermined current threshold value Cth.

[0060] According to this embodiment, the disconnection detection process is disabled for the period from the power supply start time t0 until the drive current Id reaches a predetermined current threshold value Cth, so it is possible to provide a motor disconnection detection device that can suppress erroneous detection of disconnection of a pair of motor connection lines H1, H2 in an operating region where the drive current Id of the motor 3 is relatively small.

[0061] In the motor disconnection detection device according to this embodiment, the motor drive circuit 2 supplies a drive current Id to the motor 3 based on a PWM signal, and the processing unit sets a mask period based on the duty ratio of the PWM signal. According to this embodiment, it is possible to appropriately set the mask period.

[0062] Furthermore, the motor control device 1 according to this embodiment has the motor disconnection detection device as a secondary function. This embodiment makes it possible to provide a motor control device 1 that can suppress erroneous detection of disconnections in the pair of motor connection lines H1, H2 in an operating region where the drive current Id of the motor 3 is relatively small.

[0063] The present invention is not limited to the above-described embodiment, and the following modifications are possible. (1) In the above embodiment, the motor drive circuit 2 is configured with four IGBTs (switching transistors SW1 to SW4), but the present invention is not limited to this. Switching transistors other than IGBTs may also be used as the motor drive circuit in the present invention.

[0064] (2) In the above embodiment, the motor drive circuit 2 includes a pair of switching legs. However, the present invention is not limited to this. For example, a three-phase inverter circuit may be used as the motor drive circuit of the present invention. In this case, the motor is a three-phase motor consisting of a U phase, a V phase, and a W phase.

[0065] In this case, the motor drive circuit (three-phase inverter circuit) and the motor are connected to each other by three motor connection lines through which three-phase drive current flows. Therefore, the motor control device (motor disconnection detection device, processing unit) detects a disconnection of any of the three motor connection lines.

[0066] (3) In the above embodiment, since the present invention is applied to the power generating device A that uses PWM signals as the four control signals a1 to a4, the mask period is set based on the duty ratio of the PWM signals as shown in FIG. 4. However, the four control signals a1 to a4 are not limited to PWM signals. The present invention can be applied to motors controlled by various types of control signals. [Explanation of symbols]

[0067] A. Power generating device a1~a4 Control signal (PWM signal) b Current detection signal Id Drive current H1, H2 motor connection wires 1. Motor control device (motor disconnection detection device, processing unit) 2 Motor drive circuit 3 motors 4 Current Sensor

Claims

1. 1. A motor wire breakage detection device including a processing unit that detects a wire breakage in a motor connection line connecting an output terminal of a motor drive circuit and an input terminal of a motor based on a drive current supplied from the motor drive circuit to the motor via the motor connection line, The motor disconnection detection device is characterized in that the processing unit disables disconnection detection processing for a period from the start of power supply until the drive current reaches a predetermined threshold value.

2. the motor drive circuit supplies the drive current to the motor based on a PWM signal; 2. The motor disconnection detection device according to claim 1, wherein the processing unit sets the period based on a duty ratio of the PWM signal.

3. A motor control device comprising the motor disconnection detection device according to claim 1 or 2.

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