Motor control device and washing machine

Abstract

To provide a motor controller capable of avoiding the use of a special control circuit in which the input of a negative voltage is allowed.SOLUTION: A selection circuit that selects a target motor that is a motor to be driven among the plurality of motors, a drive circuit that drives the target motor selected by the selection circuit, a current detection circuit that detects an AC current including a negative component flowing through the target motor when the target motor is driven, and a control circuit that controls the drive circuit based on the AC current, the current detection circuit includes a shunt resistor configured to output a first volts alternating current corresponding to the AC current, and a bias circuit configured to output a second volts alternating current by adding a DC bias voltage corresponding to the target motor to the first volts alternating current.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a motor control device and a washing machine. [Background technology]

[0002] A motor drive device according to the background art is disclosed in Patent Document 1. The motor drive device according to the background art detects motor current using a shunt resistor and a current detection IC equipped with a differential amplifier circuit capable of inputting negative voltages and switching the gain. The motor drive device also switches the load relay and the gain of the current detection IC depending on the motor being driven by the control means. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-239515 Summary of the Invention [Problem to be solved by the invention]

[0004] The motor drive device according to the background art uses a special control circuit that can input a negative voltage, which reduces versatility and limits options when selecting components.

[0005] An object of the present disclosure is to provide a motor control device that can avoid the use of a special control circuit that allows input of a negative voltage, and a washing machine equipped with the same. [Means for solving the problem]

[0006] A motor control device according to one aspect of the present disclosure is a motor control device that controls the driving of multiple motors that have different rated currents and are not driven simultaneously, and includes a selection circuit that selects a target motor from the multiple motors that is to be driven, a drive circuit that drives the target motor selected by the selection circuit, a current detection circuit that detects an AC current containing a negative component that flows through the target motor when the target motor is driven, and a control circuit that controls the drive circuit based on the AC current, wherein the current detection circuit has a shunt resistor that outputs a first AC voltage corresponding to the AC current, and a bias circuit that outputs a second AC voltage that does not contain a negative component by adding a DC bias voltage corresponding to the target motor to the first AC voltage.

[0007] A washing machine according to another aspect of the present disclosure includes a washing tub for storing laundry, multiple motors having different rated currents and that are not driven simultaneously during a washing operation, and a motor control device according to the above aspect that controls the driving of the multiple motors. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to avoid the use of a special control circuit that allows the input of a negative voltage, thereby increasing versatility and expanding the options available when selecting components. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a main part schematically illustrating a configuration of a washing machine according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a simplified functional configuration of the washing machine. [Figure 3] FIG. 2 is a diagram showing a simplified configuration example of a drive circuit and a current detection circuit. [Figure 4] FIG. 10 is a diagram showing a simplified configuration example of a shunt resistor and a bias circuit. [Figure 5] FIG. 2 is a diagram illustrating a simplified configuration example of a selection circuit. [Figure 6] FIG. 2 is a diagram illustrating a simplified configuration example of a bias circuit. [Figure 7] FIG. 2 is a diagram illustrating a simplified configuration example of a selection circuit. [Figure 8] FIG. 2 is a simplified diagram showing part of the configuration of a control circuit. [Figure 9] 10A and 10B are diagrams showing signal waveforms of a washing machine during washing operation. [Figure 10] 10A and 10B are diagrams showing signal waveforms of a washing machine during washing operation. [Figure 11] 10A and 10B are diagrams showing signal waveforms of a washing machine during washing operation. [Figure 12] 10A and 10B are diagrams showing signal waveforms of a washing machine during washing operation. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Findings that formed the basis of this disclosure) The motor drive device according to the background art disclosed in Patent Document 1 includes an inverter circuit that converts DC power to AC power, multiple motors driven by the inverter circuit, a load relay that switches wiring so that the inverter circuit's output is connected to a single motor, current detection means connected to the negative voltage side of the inverter circuit and detecting the motor current when the inverter circuit's lower arm switching means is conductive, and control means that controls the inverter circuit to drive the motors using the output signal of the current detection means. The current detection means includes a shunt resistor and a current detection IC that receives and differentially amplifies the voltage across the shunt resistor. The current detection IC has a differential amplifier circuit that can accept negative voltages and has a switchable gain, and the control means switches the gain of the load relay and the current detection IC depending on the motor being driven. The motor drive device according to the background art can achieve smaller size, fewer components, a smaller mounting area, and lower costs in motor drive devices such as washing machines that use inverter circuits to drive multiple motors.

[0011] However, the motor drive device according to the background art uses a special control circuit that can input a negative voltage, which reduces versatility and limits the options available when selecting components.

[0012] In order to solve this problem, the inventor discovered that by adding a DC bias voltage corresponding to the target motor to be driven to the output voltage of the shunt resistor, an AC voltage that does not contain negative components can be input to the control circuit, thereby avoiding the use of a special control circuit that is capable of inputting negative voltages, and this finding constitutes the subject matter of the present disclosure.

[0013] Therefore, the present disclosure provides a motor control device that can avoid the use of a special control circuit that allows input of a negative voltage, and a washing machine equipped with the same.

[0014] (Embodiments of the present disclosure) Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted.

[0015] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the disclosure, and are not intended to limit the subject matter described in the claims.

[0016] FIG. 1 is a cross-sectional view of a main part schematically illustrating the configuration of a washing machine 1 according to an embodiment of the present disclosure. The washing machine 1 includes a washing tub 17, a washing motor 14, and a motor control device 11. The washing machine 1 also includes multiple motors that have different rated currents and are not driven simultaneously during a washing operation. The multiple motors include at least two of a bath pump motor 4, a circulation pump motor 5, and a drying fan motor 6. The multiple motors are not limited to this example. The washing machine 1 may be a drum-type washing machine or a vertical washing machine. The locations of the motor control device 11 and the multiple motors are not limited to the example shown in FIG. 1.

[0017] 2 is a simplified diagram showing the functional configuration of washing machine 1. Washing machine 1 includes motor control device 11, first motor 12, second motor 13, washing motor 14, first device 15, second device 16, and washing tub 17.

[0018] The motor control device 11 controls the driving of the first motor 12, the second motor 13, and the washing motor .

[0019] First motor 12 is a motor for driving first device 15, and second motor 13 is a motor for driving second device 16. For example, first device 15 is a bath pump, first motor 12 is a bath pump motor 4 for driving the bath pump, second device 16 is a circulation pump, and second motor 13 is a circulation pump motor 5 for driving the circulation pump. The bath pump is a pump for pumping remaining bath water into washing tub 17 during a water supply process included in the washing operation. The circulation pump is a pump for circulating wash water in washing tub 17 during a washing process included in the washing operation. Alternatively, first device 15 is a bath pump or a circulation pump, first motor 12 is a bath pump motor 4 or a circulation pump motor 5, second device 16 is a drying fan, and second motor 13 is a drying fan motor 6 for driving the drying fan. The drying fan is a fan for circulating warm air in washing tub 17 during a drying process included in the washing operation. Note that the first motor 12 and the second motor 13 are not limited to the above example. Furthermore, the multiple motors having different rated currents and not driven simultaneously during the washing operation may include three or more motors. In the following description, an example is taken in which the rated current of the second motor 13 is greater than the rated current of the first motor 12, and the motor current flowing through the second motor 13 during the washing operation is greater than the motor current flowing through the first motor 12. In the following description, the rated current of the first motor 12 is set to 0.75 A, and the rated current of the second motor 13 is set to 4 A, but the present invention is not limited to this example.

[0020] The washing motor 14 is a motor for driving the washing tub 17. The washing tub 17 contains laundry to be washed. The washing motor 14 may be driven simultaneously with the first motor 12 or the second motor 13 during the washing operation.

[0021] The motor control device 11 includes a control circuit 21, a drive circuit 22, a current detection circuit 23, a selection circuit 24, a drive circuit 25, and a current detection circuit 26.

[0022] The selection circuit 24 selects a target motor to be driven from either the first motor 12 or the second motor 13 based on a selection signal S3 input from the control circuit 21. The drive circuit 22 drives the target motor selected by the selection circuit 24 based on a control signal S1 input from the control circuit 21. The control signal S1 includes a position command value or a speed command value for the target motor. The current detection circuit 23 detects an AC motor current (AC current I1) that flows through the target motor when the target motor is driven. The current detection circuit 23 inputs a detection signal S2 related to the detection result of the motor current of the target motor to the control circuit 21. The control circuit 21 generates the control signal S1 based on the detection signal S2.

[0023] The control circuit 21 is configured using a microcontroller or the like. The drive circuit 22 is configured using an inverter circuit or the like. The inverter circuit is configured using, for example, an intelligent power module (hereinafter referred to as "IPM"). The IPM has a built-in three-phase full-bridge inverter circuit, a drive circuit, and a protection circuit.

[0024] The drive circuit 25 drives the wash motor 14 based on a control signal S4 input from the control circuit 21. The control signal S4 includes a position command value or a speed command value for the wash motor 14, etc. The current detection circuit 26 detects the AC motor current flowing through the wash motor 14 when the wash motor 14 is driven. The current detection circuit 26 inputs a detection signal S5 related to the detection result of the motor current of the wash motor 14 to the control circuit 21. The control circuit 21 generates the control signal S4 based on the detection signal S5. The drive circuit 25 is configured using an inverter circuit, etc. The inverter circuit is configured using an IPM, etc.

[0025] FIG. 3 is a diagram showing a simplified configuration example of the drive circuit 22 and the current detection circuit 23.

[0026] The drive circuit 22 is an IPM incorporating a three-phase full-bridge inverter circuit. The three-phase full-bridge inverter circuit has six power switching elements, such as insulated gate bipolar transistors, connected between the power supply wiring and GND wiring of the inverter circuit, and diodes connected in anti-parallel to each power switching element. The power supply wiring is a wiring that provides a high-side reference potential (power supply potential), and the GND wiring is a wiring that provides a low-side reference potential (GND potential).

[0027] The current detection circuit 23 includes current detection circuits 23a to 23c corresponding to the three phases. Since the current detection circuits 23a to 23c have the same configuration, the current detection circuit 23a will be described below. The current detection circuit 23a has a shunt resistor 31 and a bias circuit 32.

[0028] The shunt resistor 31 is connected to the GND wiring of the inverter circuit. The current detection circuit 23a detects an AC current I1 (motor current) containing a negative component that flows through the target motor when the target motor is driven. The shunt resistor 31 outputs a first AC voltage corresponding to the AC current I1.

[0029] The bias circuit 32 adds a DC bias voltage corresponding to the target motor to the first AC voltage, thereby outputting a second AC voltage (detection signal S2a) that does not contain a negative component.

[0030] 4 is a simplified diagram showing an example configuration of the shunt resistor 31 and bias circuit 32. The bias circuit 32 includes a voltage-dividing pull-down resistor 41 connected to the shunt resistor 31, a voltage-dividing pull-up resistor 42 connected to the voltage-dividing pull-down resistor 41, and a switching circuit that switches the resistance value of the voltage-dividing pull-up resistor 42 in accordance with the target motor. The switching circuit includes a switching element 44 for adjusting the voltage-dividing resistor and a voltage-dividing adjustment resistor 43. The switching element 44 is configured using a MOSFET or the like.

[0031] As shown in Figure 4, the resistance value of shunt resistor 31 is R0, the resistance value of voltage-dividing pull-down resistor 41 is R1, the resistance value of voltage-dividing pull-up resistor 42 is R2, and the resistance value of voltage-dividing adjustment resistor 43 is R3. For example, resistance value R0 is 0.2Ω, resistance value R1 is 2 kΩ, resistance value R2 is 39 kΩ, and resistance value R3 is 10 kΩ. However, this example is not limiting. Note that resistance value R0 is sufficiently small compared to resistance values ​​R1 to R3, so resistance value R0 can be ignored in calculating the bias voltage.

[0032] When the switching element 44 is turned off based on a high-level selection signal S3 input from the control circuit 21, the resistance of the voltage-dividing pull-up resistor 42 becomes resistance R2. In this case, the voltage of the DC bias voltage becomes the value obtained by dividing the power supply potential by resistances R1 and R2. If the power supply potential is VDD, the voltage of the DC bias voltage is VDD×R1 / (R1+R2). If the power supply potential VDD is 5V, the voltage of the DC bias voltage is 5×2k / (2k+39k)=0.24V.

[0033] When the switching element 44 is turned on based on a low-level selection signal S3 input from the control circuit 21, the resistance of the voltage-dividing pull-up resistor 42 becomes a combined resistance value R23 of the resistance values ​​R2 and R3. The combined resistance value R23 is (R2×R3) / (R2+R3). In this case, the voltage value of the DC bias voltage becomes the value obtained by dividing the power supply potential by the resistance value R1 and the combined resistance value R23. If the power supply potential is VDD, the voltage value of the DC bias voltage is VDD×R1 / (R1+R23). The combined resistance value R23 is (39kΩ×10kΩ) / (39kΩ+10kΩ)=8kΩ. Therefore, if the power supply potential VDD is 5V, the voltage value of the DC bias voltage is 5×2kΩ / (2kΩ+8kΩ)=1V.

[0034] The voltage value of the DC bias voltage is set based on the amplitude of the first AC voltage according to the target motor, and the resistance values ​​R1 to R3 are set so as to realize the voltage value of the DC bias voltage.

[0035] 5 is a diagram showing a simplified example of the configuration of the selection circuit 24. The selection circuit 24 is configured using, for example, a mechanical relay 50 and a switching element 53. The mechanical relay 50 includes a contact 51 that connects the drive circuit 22 to the first motor 12 or the second motor 13, and a coil 52 that controls the switching of the contact 51. The switching element 53 is configured using a bipolar transistor or the like, and is connected to the coil 52.

[0036] When the switching element 53 is turned on based on a high-level selection signal S3 input from the control circuit 21, current flows through the coil 52, generating magnetic flux, and the contact 51 connects the drive circuit 22 and the first motor 12.

[0037] When the switching element 53 is turned off based on a low-level selection signal S3 input from the control circuit 21, the magnetic flux of the coil 52 disappears and the contact 51 connects the drive circuit 22 and the second motor 13.

[0038] In addition, when the plurality of motors having different rated currents and not driven simultaneously during the washing operation include three or more motors, the voltage value of the DC bias voltage can be switched according to the selection of three or more target motors by cascading a plurality of selection circuits 24, providing a plurality of the above-mentioned switching circuits in the bias circuit 32, and setting the number of bits of the selection signal S3 to multiple bits.

[0039] 6 and 7 are simplified diagrams showing examples of the configuration of the bias circuit 32 and the selection circuit 24, respectively, when selecting from three motors. The multiple motors include a first motor 12, a second motor 13, and a third motor 19. The selection signal S3 is two bits long and includes a selection signal S31 corresponding to the first bit and a selection signal S32 corresponding to the second bit.

[0040] 6, the switching circuit includes a first switching circuit and a second switching circuit. The first switching circuit includes a switching element 441 and a voltage division adjustment resistor 431. The switching element 441 is controlled by a selection signal S31. The resistance value of the voltage division adjustment resistor 431 is assumed to be R31. The second switching circuit includes a switching element 442 and a voltage division adjustment resistor 432. The switching element 442 is controlled by a selection signal S32. The resistance value of the voltage division adjustment resistor 432 is assumed to be R32.

[0041] Referring to FIG. 7, two selection circuits 24 are cascade-connected. The two selection circuits 24 include a front-stage selection circuit 241 and a rear-stage selection circuit 242. The selection circuit 242 switches between the second motor 13 and the third motor 19 in response to a selection signal S31. The selection circuit 241 switches between the first motor 12 and the selection circuit 242 in response to a selection signal S32. The selection circuit 242 is configured using, for example, a mechanical relay 502 and a switching element 532. The mechanical relay 502 includes a contact 512 that connects the selection circuit 241 with the second motor 13 or the third motor 19, and a coil 522 that controls the switching of the contact 512. The switching element 532 is configured using a bipolar transistor or the like and is connected to the coil 522. The selection circuit 241 is configured using, for example, the mechanical relay 501 and the switching element 531. The mechanical relay 501 includes a contact 511 that connects the drive circuit 22 to the first motor 12 or the selection circuit 242, and a coil 521 that controls the switching of the contact 511. The switching element 531 is configured using a bipolar transistor or the like, and is connected to the coil 521.

[0042] When both selection signals S31 and S32 are at a high level, the first motor 12 is selected and the DC bias voltage has a first voltage value. When selection signal S31 is at a high level and selection signal S32 is at a low level, the second motor 13 is selected and the DC bias voltage has a second voltage value that is higher than the first voltage value. When both selection signals S31 and S32 are at a low level, the third motor 19 is selected and the DC bias voltage has a third voltage value that is higher than the second voltage value.

[0043] 8 is a simplified diagram showing part of the configuration of the control circuit 21. The control circuit 21 includes an amplifier circuit 62 and an AD conversion circuit 63.

[0044] The amplifier circuit 62 receives the second AC voltage (detection signal S2) from the current detection circuit .

[0045] The amplifier circuit 62 generates a third AC voltage S11 by amplifying the second AC voltage S2 with an amplification factor according to the target motor, and inputs the third AC voltage S11 to the AD conversion circuit 63.

[0046] The AD conversion circuit 63 converts the third AC voltage S11, which is an analog signal, into voltage data S12, which is a digital signal. The control circuit 21 generates and outputs control signals S1 and S4 based on the voltage data S12 as the washing operation progresses. The control circuit 21 also generates and outputs a selection signal S3 as the washing operation progresses.

[0047] 9 to 12 are diagrams showing signal waveforms of washing machine 1 during washing operation. For comparison, (A) of each diagram shows the signal waveform when first motor 12 with a small rated current is selected as the target motor, and (B) of each diagram shows the signal waveform when second motor 13 with a large rated current is selected as the target motor.

[0048] Fig. 9 shows an example of a motor current waveform of the washing machine 1. Fig. 9(A) shows AC current I1A that flows through first motor 12 when first motor 12 is selected. In this embodiment, the rated current of first motor 12 is 0.75 A, so AC current I1A fluctuates within a range of -0.75 A to +0.75 A with 0 A as the reference.

[0049] 9B shows AC current I1B that flows through second motor 13 when second motor 13 is selected. In this embodiment, the rated current of second motor 13 is 4 A, so AC current I1B fluctuates within a range of −4 A to +4 A with 0 A as the reference.

[0050] Fig. 10 shows a voltage waveform converted from the waveform of Fig. 9. Fig. 10(A) shows the first AC voltage V1A output from the shunt resistor 31 when the first motor 12 is selected. In this embodiment, the resistance value R0 of the shunt resistor 31 is 0.2Ω, so the first AC voltage V1A fluctuates within a range of -0.15V to +0.15V with 0V as the reference. In other words, the amplitude X1 of the first AC voltage V1A is 0.15V.

[0051] 10(B) shows the first AC voltage V1B output from the shunt resistor 31 when the second motor 13 is selected. In this embodiment, the resistance value R0 of the shunt resistor 31 is 0.2Ω, so the first AC voltage V1B fluctuates within a range of −0.8V to +0.8V with 0V as the reference. In other words, the amplitude X2 of the first AC voltage V1B is 0.8V.

[0052] FIG. 11 shows the waveform of FIG. 10 after a DC bias component is applied. (A) of FIG. 11 shows the second AC voltage V2A output from the bias circuit 32 when the first motor 12 is selected. In this embodiment, the voltage value Y1 of the DC bias voltage when the first motor 12 is selected (when the selection signal S3 is at a high level) is 0.24 V. Therefore, the second AC voltage V2A fluctuates within a range of −0.15 V to +0.15 V, i.e., +0.09 V to +0.39 V, with 0.24 V as the reference. As a result, the second AC voltage V2A does not contain a negative component. The second AC voltage V2A is input from the current detection circuit 23 to the control circuit 21 as the detection signal S2. Therefore, a general-purpose control circuit that does not allow the input of a negative voltage can be used as the control circuit 21.

[0053] 11B shows the second AC voltage V2B output from the bias circuit 32 when the second motor 13 is selected. In this embodiment, the voltage value Y2 of the DC bias voltage when the second motor 13 is selected (when the selection signal S3 is at a low level) is 1 V. Therefore, the second AC voltage V2V fluctuates within a range of −0.8 V to +0.8 V, that is, within a range of +0.2 V to +1.8 V, with 1 V as the reference. As a result, the second AC voltage V2B does not contain a negative component. The second AC voltage V2B is input from the current detection circuit 23 to the control circuit 21 as the detection signal S2. Therefore, a general-purpose control circuit that does not allow the input of a negative voltage can be used as the control circuit 21.

[0054] 12A shows the third AC voltage S11A output from the amplifier circuit 62 when the first motor 12 is selected. In this embodiment, the amplification factor of the amplifier circuit 62 when the first motor 12 is selected is set to, for example, 10 times so that the voltage fluctuation range after amplification falls within the input voltage range of the AD conversion circuit. In this case, the amplifier circuit 62 amplifies a signal in the range of +0.09V to +0.39V to an amplitude X3, and outputs the third AC voltage S11A whose voltage value fluctuates within the range of +0.9V to +3.9V.

[0055] 12(B) shows the third AC voltage S11B output from the amplifier circuit 62 when the second motor 13 is selected. In this example of the present embodiment, the amplification factor of the amplifier circuit 62 when the second motor 13 is selected is set to, for example, 2x so that the voltage fluctuation range after amplification falls within the input voltage range of the AD conversion circuit. In this case, the amplifier circuit 62 amplifies a signal in the range of +0.2V to +1.8V to an amplitude X4, and outputs the third AC voltage S11B whose voltage value fluctuates within the range of +0.4V to +3.6V.

[0056] In the above embodiment, the washing machine 1 has been described as an example of an appliance equipped with the motor control device 11, but the application of the motor control device 11 is not limited to the washing machine 1. The motor control device 11 can be applied to any appliance or facility that has multiple motors with different rated currents that are not driven simultaneously.

[0057] As a first example, motor control device 11 may be applied to a dishwasher. The dishwasher includes, as the plurality of motors having different rated currents and not driven simultaneously, a motor for driving a circulation pump that circulates water during washing and a motor for driving a blower fan during drying.

[0058] As a second example, the motor control device 11 may be applied to an elevator. The elevator includes, as the plurality of motors having different rated currents and not driven simultaneously, a motor for driving a drive unit that raises and lowers the car and a motor for driving a drive unit that opens and closes the door.

[0059] As a third example, the motor control device 11 may be applied to a disk drive device such as a PC or a game console. The disk drive device includes a motor for rotating a disk and a motor for driving a drive unit that opens and closes a tray, as the plurality of motors having different rated currents and that are not driven simultaneously.

[0060] As in the above embodiment, motor control device 11 according to a first aspect of the present disclosure is a motor control device that controls the driving of multiple motors that have different rated currents and are never driven simultaneously, and includes: a selection circuit 24 that selects a target motor that is a motor to be driven from the multiple motors; a drive circuit 22 that drives the target motor selected by selection circuit 24; a current detection circuit 23 that detects an AC current containing a negative component that flows through the target motor when it is driven; and a control circuit 21 that controls drive circuit 22 based on the AC current. Current detection circuit 23 includes a shunt resistor 31 that outputs a first AC voltage corresponding to the AC current, and a bias circuit 32 that outputs a second AC voltage that does not contain a negative component by adding a DC bias voltage corresponding to the target motor to the first AC voltage.

[0061] According to this aspect, it is possible to avoid the use of a special control circuit that allows the input of a negative voltage, thereby improving versatility and expanding the options available when selecting components.

[0062] In addition, in the motor control device 11 according to the second aspect of the present disclosure, in the first aspect, it is preferable that the DC bias voltage is set based on the amplitude of the first AC voltage according to the target motor.

[0063] According to this aspect, it is possible to set a DC bias voltage of an appropriate voltage value that does not contain a negative component.

[0064] In addition, in the motor control device 11 according to the third aspect of the present disclosure, in the first or second aspect, the bias circuit 32 preferably includes a voltage-dividing pull-down resistor 41 connected to the shunt resistor 31, a voltage-dividing pull-up resistor 42 connected to the voltage-dividing pull-down resistor 41, and a switching circuit (a switching element 44 and a voltage-dividing adjustment resistor 43) that switches the resistance value of the voltage-dividing pull-up resistor 42 according to the target motor.

[0065] According to this aspect, the DC bias voltage corresponding to the selected target motor can be set with a simple configuration and processing.

[0066] Furthermore, in the motor control device 11 according to the fourth aspect of the present disclosure, in the third aspect, the control circuit 21 outputs a selection signal S3 for selecting the target motor, the selection signal S3 is input to the selection circuit 24 and the switching circuit, the selection circuit 24 selects the target motor based on the selection signal S3, and the switching circuit switches the resistance value of the voltage-dividing pull-up resistor 42 based on the selection signal S3.

[0067] According to the fourth aspect, the number of ports used by the control circuit 21 can be reduced by consolidating the control signals, compared to when the control signal for the selection circuit and the control signal for the switching circuit are output from different ports of the control circuit 21.

[0068] Furthermore, in the motor control device 11 according to a fifth aspect of the present disclosure, in any one of the first to fourth aspects, the control circuit 21 preferably has an AD conversion circuit 63 having a predetermined input voltage range and converting an analog signal into a digital signal, and an amplifier circuit 62 that generates a third AC voltage by amplifying the second AC voltage with an amplification factor corresponding to the target motor and inputs the third AC voltage to the AD conversion circuit 63.

[0069] According to this aspect, it is possible to perform an optimal AD conversion process according to the selected target motor.

[0070] A washing machine 1 according to a sixth aspect of the present disclosure includes a washing tub 17 for accommodating laundry, a plurality of motors having different rated currents and not driven simultaneously during a washing operation, and a motor control device 11 according to any one of the first to fifth aspects for controlling the driving of the plurality of motors.

[0071] According to this embodiment, the motor control device 11 can avoid the use of a special control circuit that allows the input of negative voltages, thereby increasing versatility and expanding the options available when selecting components.

[0072] It should be noted that the above-described embodiments are intended to illustrate the technology of the present disclosure, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0073] The present disclosure is widely applicable to motor control devices that control the driving of multiple motors that have different rated currents and are not driven simultaneously. [Explanation of symbols]

[0074] 1 washing machine 4. Bus pump motor 5 Circulation pump motor 6 Drying fan motor 11 Motor control device 12 First motor 13 Second motor 14 Washing motor 15 1st device 16 2nd device 17 Washing machine 21 Control circuit 22 Drive circuit 23 Current detection circuit 24 Selection circuit 31 Shunt resistor 32 Bias circuit 41 Voltage divider pull-down resistor 42 Voltage divider pull-up resistor 43 split adjustment resistor 44 Switching element 62 Amplifier circuit 63 AD conversion circuit

Claims

1. A motor control device that controls the driving of multiple motors that have different rated currents and are not driven simultaneously, a selection circuit for selecting a target motor to be driven from among the plurality of motors; a drive circuit for driving the target motor selected by the selection circuit; a current detection circuit for detecting an AC current including a negative component that flows through the target motor when the target motor is driven; a control circuit that controls the drive circuit based on the AC current; Equipped with The current detection circuit a shunt resistor that outputs a first AC voltage according to the AC current; a bias circuit that outputs a second AC voltage that does not include a negative component by adding a DC bias voltage corresponding to the target motor to the first AC voltage; having Motor control device.

2. the DC bias voltage is set based on the amplitude of the first AC voltage corresponding to the target motor. The motor control device according to claim 1 .

3. The bias circuit a voltage-dividing pull-down resistor connected to the shunt resistor; a voltage-dividing pull-up resistor connected to the voltage-dividing pull-down resistor; a switching circuit that switches the resistance value of the voltage dividing pull-up resistor according to the target motor; Including, The motor control device according to claim 1 .

4. the control circuit outputs a selection signal for selecting the target motor; the selection signal is input to the selection circuit and the switching circuit, the selection circuit selects the target motor based on the selection signal; the switching circuit switches the resistance value of the voltage-dividing pull-up resistor based on the selection signal; The motor control device according to claim 3 .

5. The control circuit an AD conversion circuit having a predetermined input voltage range and converting an analog signal into a digital signal; an amplifier circuit that generates a third AC voltage by amplifying the second AC voltage by an amplification factor corresponding to the target motor and inputs the third AC voltage to the AD conversion circuit; having The motor control device according to claim 1 .

6. a washing tub for storing laundry; A plurality of motors having different rated currents and not driven simultaneously during a washing operation; a motor control device according to any one of claims 1 to 5, which controls the driving of the plurality of motors; Equipped with washing machine.

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