JP6407556B2 - Washing machine - Google Patents

Description

  Embodiments described herein relate generally to a washing machine.

  Conventionally, there have been the following first to fourth conventional examples as functions for detecting disconnection of a motor in a washing machine (Patent Documents 1 to 4). In the first conventional example (Patent Document 1), a three-phase brushless DC motor is driven by an inverter circuit, and among the three-phase currents output to the motor, the current value of one phase is another two-phase. When the state of being equal to or less than a predetermined value compared to the current value continues for a predetermined time (5 seconds), it is determined that the wire is disconnected.

  In the second conventional example (Patent Document 2), an overcurrent detecting means for detecting an overcurrent of the inverter circuit is provided, and when an overcurrent abnormality is repeatedly detected a predetermined number of times or more, it is determined that a circuit failure, a motor disconnection, or a short circuit has occurred. And prohibit driving. In the third conventional example (Patent Document 3), when a motor having a three-phase winding is driven by an inverter circuit, the inverter current is detected every time the energized phase of the three-phase winding is detected by the sensor. When the current is not detected in the specific phase, it is determined that the wire is disconnected. In the fourth conventional example (Patent Document 4), which has a triac-driven induction motor, the current flowing through the load output line is detected by a current transformer, and the current is detected in accordance with each step of the washing operation. . Whether there is an open or short circuit abnormality is determined.

JP 2009-61164 A JP 2001-327175 A Japanese Patent Laid-Open No. 10-145960 Japanese Patent Laid-Open No. 10-249089

  However, the above-described conventional techniques have the following drawbacks. That is, in the first conventional example, since the motor current is alternating current and constantly fluctuates, the absolute value is taken and averaged over a certain interval, and further compared with the other two phases to eliminate malfunction. For this reason, taking into account the case of low rotation, it takes a relatively long time for detection, and a delay time in seconds occurs for abnormality detection. Although it is possible to detect if it is a complete disconnection, in the case of an instantaneous disconnection in a half-contact state, it may not be detected because the disconnection time is short.

  In the second conventional example, a large current is generated in the remaining two other than the one that was cut off during the discharge due to an instantaneous disconnection, and an overcurrent abnormality is detected, but the amount of clothes is small and the motor load is originally small. In the case of overload due to a large amount of clothing, even if there was no abnormality, the motor current increased due to the overload, and there was a high risk of erroneous detection.

  In the third conventional example, when 120 ° energization (rectangular wave) is applied, the stationary phase is energized according to the detection of the rotor position sensor. Therefore, if the inverter current is checked when the position sensor signal is switched, an abnormality is detected in the disconnection phase. However, with 180 ° energization (sinusoidal wave), switching energization is continuously performed little by little, so that an abnormality cannot be clearly detected. In the fourth conventional example, in a three-phase motor using an inverter, even if only one phase is instantaneously disconnected, energization is continued in the remaining two phases, so even if the overall current is detected by a current transformer, Abnormality cannot be judged.

  Accordingly, a washing machine that includes a three-phase motor, can cope with instantaneous disconnection, and can reliably detect disconnection of the motor is provided.

The washing machine of the embodiment is configured to drive and control a three-phase motor by a PWM inverter circuit, and to perform a washing operation by a rotational driving force generated by the three-phase motor. current detecting means for detecting a, a disconnection determination unit that determines breakage of the phase windings of the three-phase motor, the disconnection determination means of the line voltage between each phase of the three-phase motor, either in the timing Kano line voltage is greater than or equal to the reference value, if the detected current value of the phase current corresponding to the line voltage reaches or exceeds the reference value by the current detecting means has continued following the state threshold predetermined time In addition, it is characterized in that it is determined as a disconnection.

The longitudinal cross-sectional view which shows one Embodiment and shows the whole structure of a washing machine roughly Diagram showing the configuration of the three-phase motor drive control system The figure which explains the content of sine wave drive, and shows the waveform (a) and the line voltage waveform (b) of the output signal wave of each phase The figure which shows an example of the waveform of the motor current in the washing process The flowchart which shows the process sequence of the disconnection determination which a control circuit performs The figure which shows the example of the threshold value etc. which is used for the decision in each process

  Hereinafter, an embodiment applied to a vertical automatic washing machine will be described with reference to the drawings. First, FIG. 1 schematically shows a configuration of a washing machine (fully automatic washing machine) 1 according to the present embodiment. Here, in the washing machine 1, a water tank 3 for storing washing water is elastically supported (suspended and supported) by an elastic suspension mechanism 4 in an outer box 2 having a rectangular shape as a whole. . As shown only partially, the elastic suspension mechanism 4 has, for example, four suspension rods 4a provided at the four corners of the outer box 2, and springs 4b disposed at the lower end portions of the suspension rods 4a. The known configuration is provided.

  In the water tank 3, there is rotatably provided a vertical tank 5 having a cylindrical shape with a bottom. For example, a liquid-filled rotary balancer 5 a is attached to the upper end of the rotary tank 5. Further, a dewatering hole 5 b is formed at the upper end of the peripheral wall portion of the rotating tub 5. A laundry (not shown) is accommodated in the rotating tub 5, and the laundry is washed, rinsed, dehydrated, and dried.

  A stirring body (pulsator) 6 is disposed at the inner bottom of the rotating tank 5. Further, a water passage 7 is formed at the bottom of the rotary tank 5, and this water passage 7 communicates with the drain 8 through a drain passage 7a. A drainage channel 10 having an electronically controlled drainage valve 9 is connected to the drainage port 8. Therefore, when water is supplied into the rotary tank 5 with the drain valve 9 closed, water is stored in the rotary tank 5, and when the drain valve 9 is opened, the water in the rotary tank 5 is discharged into the drain passage 7 a, the drain port 8, and It is discharged through the drainage channel 10. An auxiliary drainage port 8a is formed at the bottom of the water tank 3, and this auxiliary drainage port 8a is connected to the drainage channel 10 by bypassing the drainage valve 9 via a connection hose (not shown). Is rotated, the water discharged from the upper part into the water tank 3 is discharged.

  Further, an outer rotor type DC three-phase brushless motor 14 (hereinafter simply referred to as a three-phase motor 14) and a drive mechanism section 11 are disposed on the outer bottom of the water tank 3. The drive mechanism 11 includes a hollow tank shaft 12, a stirring shaft 13 that passes through the tank shaft 12, a clutch mechanism (not shown) that selectively transmits the rotation of the three-phase motor 14 to them. The rotating tank 5 is connected to the upper end of the tank shaft 12, and the stirring body 6 is connected to the upper end of the stirring shaft 13.

  The clutch mechanism operates in conjunction with the drain valve 9, and during the washing and rinsing (washing process), the rotating tank 5 is fixed (stopped) and the driving force of the three-phase motor 14 is applied to the stirring shaft 13. To the stirrer 6 and the stirrer 6 is directly driven forward and reverse at low speed. Further, at the time of dehydration (dehydration process), the driving force of the three-phase motor 14 is transmitted to the rotary tank 5 via the tank shaft 12 in a state where the tank shaft 12 and the stirring shaft 13 are connected, and the rotary tank 5 (and The stirring body 6) is directly driven to rotate in one direction at a high speed.

  On the other hand, a top cover 15 made of a synthetic resin having a thin hollow box shape is attached to the upper portion of the outer box 2. A substantially circular laundry doorway (not shown) is formed at the center of the top surface of the top cover 15 and is located above the rotating tub 5, and is a two-fold type lid for opening and closing the laundry doorway. 16 is provided. Also. A well-known water supply mechanism for supplying water into the water tank 3 is provided at the rear portion of the top cover 15. Although not shown in detail, an operation panel is provided on the front portion of the top cover 15 for the user to select a course for washing operation and instruct the start of operation. Further, on the back side of the operation panel, a control circuit 17 configured mainly with a computer and controlling the entire washing machine 1 is provided.

  Although not described in detail, the control circuit 17 controls the water supply valve, the drain valve 9, the three-phase motor 14 and the like based on operation signals from the operation panel and signals from various sensors, and a washing (rinsing) process. A washing operation including a dehydration process and the like is executed. In the washing process, the three-phase motor 14 rotates forward and reverse at 100 rpm to 150 rpm every 1 to several seconds. In this washing process, although the rotation is relatively low, the load torque is large and the motor current is large. In the dehydration process, the three-phase motor 14 rotates at a maximum of about 900 rpm. In this dehydration process, the rotational speed is large but the load torque is small, and the motor current is small.

  FIG. 2 shows a drive control system of the three-phase motor 14. The three-phase motor 14 includes three-phase windings 14u, 14v, and 14w, and is driven and controlled by a PWM-type inverter circuit 21. It has come to be. The inverter circuit 21 is configured by connecting six IGBTs (semiconductor switching elements) 22a to 22f in a three-phase bridge, and flywheel diodes 23a to 23f are connected between collectors and emitters of the IGBTs 22a to 22f. Has been. Each phase output terminal 30u, 30v, 30w of the inverter circuit 42 is connected to each phase terminal (each phase winding 14u, 14v, 14w) of the motor 14.

  The emitters of the IGBTs 22d, 22e, and 22f on the lower arm side of the inverter circuit 21 are connected to a DC power supply line 35b (ground) via shunt resistors (current detection resistors) 24u, 24v, and 24w, respectively. An interconnection point between the emitters of the IGBTs 22d, 22e, and 22f and the shunt resistors 24u, 24v, and 24w is connected to the level shift amplification circuit 25 and the overcurrent determination circuit 26.

  The level shift amplifier circuit 25 is configured to perform level shift and amplification of the terminal voltages of the shunt resistors 24u, 24v, 24w, and to provide the control circuit 17 as a current detection signal. Thus, current detecting means for individually detecting the phase current of the three-phase motor 14 is configured from the shunt resistors 24u, 24v, 24w and the like. In this case, the terminal voltages of the shunt resistors 24u, 24v, and 24w are read into the control circuit 17 when the lower-arm IGBTs 22d, 22e, and 22f are turned on. The overcurrent determination circuit 26 is provided to detect an overcurrent that occurs, for example, when the upper and lower arms of the inverter circuit 21 are short-circuited. The overcurrent determination circuit 26 detects an overcurrent based on the terminal voltages of the shunt resistors 24u, 24v, and 24w. When the current state is detected, an overcurrent detection signal is output to the control circuit 17.

  The three-phase motor 14 is provided with three position sensors 44a, 44b, and 44c that detect the rotational position of the rotor. These position sensors 44a, 44b, 44c are constituted by, for example, Hall ICs. The output terminals of the position sensors 44a, 44b, 44c are connected to the input terminals of the control circuit 17 via NOT gates 45a, 45b, 45c, respectively. The output terminals of the NOT gates 45a, 45b, and 45c are connected to the ground via capacitors 46a, 46b, and 46c, respectively. Thus, the control circuit 17 can detect the rotational direction and rotational position of the three-phase motor 14 from the sensor signals of the position sensors 44a, 44b, and 44c.

  A DC power supply circuit unit 31 is connected to the input side of the inverter circuit 21. The DC power supply circuit unit 31 rectifies a 100V AC power supply 32 by a full-wave rectification circuit 33 constituted by a diode bridge and two capacitors 34a and 34b connected in series, and double-voltage full-wave rectification, and a DC power supply line 35a. , 35b is configured to output a DC voltage of about 280V. The DC power supply line 35b is connected to the ground. An inductor 36 is connected in series between the AC power supply 32 and one input terminal of the full-wave rectifier circuit 33. The inverter circuit 21 is connected between the DC power supply lines 35a and 35b.

  The first power supply circuit 51 steps down the drive power supply of about 280V supplied to the inverter circuit 21 to generate a 15V power supply, and supplies it to the control circuit 17 and the drive circuit 52. The second power supply circuit 53 (control power supply circuit) is a three-terminal regulator that steps down the drive power supply to generate a control power of 5 V and supplies the control power to the control circuit 17. The high voltage driver circuit 54 is arranged to drive the IGBTs 22 a to 22 c on the upper arm side in the inverter circuit 21. A series circuit of resistance elements 55 a and 55 b is connected between the DC power supply lines 35 a and 35 b, and a common connection point between them is connected to an input terminal of the control circuit 17.

  The control circuit 17 is mainly composed of a microcomputer, detects a current flowing through each phase of the inverter circuit 21 via the level shift amplifier circuit 25, that is, a current flowing through each phase winding of the three-phase motor 14, Based on the detected current value and a speed command given from the outside, vector control of the three-phase motor 14 is performed. At this time, the control circuit 17 generates three-phase upper and lower PWM signals (energization control signals) in which the voltage ratio changes sinusoidally by performing voltage / phase control, and controls the inverter circuit 21.

  At this time, as shown in FIG. 3, the control circuit 17 has a sinusoidal waveform in which the phase voltage waveform of each phase output from the inverter circuit 21 is different in phase by 120 ° in electrical angle (180 ° energization: FIG. 3 ( b), the output signal waves Vu, Vv, Vw (see FIG. 3A) of each phase are generated by the two-phase modulation method. The output signal waves Vu, Vv, Vw of each phase have a non-switching period of 120 ° in electrical angle. Then, from these output signal waves Vu, Vv, Vw, for example, a three-phase PWM signal is generated by a triangular wave comparison method using a symmetric triangular wave (for example, 15.6 kHz) as a carrier wave. In addition, the upper side is output to the gates of the IGBTs 22 a to 22 f of the inverter circuit 21 via the high-voltage driver circuit 54.

  In the present embodiment, the control circuit 17 determines the disconnection of each phase winding 14u, 14v, 14w of the three-phase motor 14 mainly by its software configuration (execution of the disconnection determination processing program). A function as a means is realized. FIG. 4 shows an example of a current waveform of each phase winding 14u, 14v, 14w of the three-phase motor 14 in the washing process. Here, in the u-phase winding 14u, an instantaneous disconnection (0. 1) is generated.

  In the present embodiment, as will be described in detail in the following description of operation (flowchart description), the control circuit 17 has a line voltage composed of PWM duty between the phases of the three-phase motor 14 equal to or higher than a reference value Sv (for example, 85 V). When a state where the detected current value of each phase by the shunt resistors 24u, 24v, 24w is equal to or lower than a threshold value Sc (for example, 0.5 A) continues for a predetermined time St (for example, 0.3 seconds). It is determined to be a disconnection.

  At this time, if the control circuit 17 determines that the winding of the winding of the three-phase motor 14 is broken, the control circuit 17 stores the abnormality occurrence in the nonvolatile memory 18 (see FIG. 2) and stops driving the three-phase motor 14. The display of the operation panel indicates that an abnormality has occurred (that repair is necessary). In the state where the occurrence of abnormality is stored in the nonvolatile memory 18, even when the washing machine 1 is turned on next time, the prohibition of operation is continued.

  In the present embodiment, the disconnection determination process is executed in each of the washing process, the dehydration process, and the brake process in the washing operation process. At this time, as shown in FIG. 6, the process is determined for each process. The reference value Sv of the individual line voltage, the threshold value Sc for current determination, and the predetermined time St are used. Furthermore, in this embodiment, the reference value Sv of the line voltage and the threshold value Sc for current determination are changed according to the number of rotations of the three-phase motor 14 in the dehydration process. In this case, it is 500 rpm or less. It is designed to change in two stages.

  Next, the operation of the washing machine 1 configured as described above will be described with reference to FIGS. The flowchart of FIG. 5 shows a processing procedure for determining disconnection of the three-phase motor 14 executed by the control circuit 17. Here, disconnection determination processing is executed every time an interrupt occurs at a cycle of 128 μs. As described above, in the PWM control, the conduction of the IGBTs 22d, 22e, and 22f on the lower arm side occurs every 64 μsec. However, the current value changes every 128 μsec due to the processing time of the control circuit 17. Read. The current value is read at a timing near the middle of the conduction period.

  First, in step S1, it is determined whether or not the motor operation command is on. If the motor operation command is not on (No in step S1), the u, v, and w phase counters are reset in step S2. Then, the process proceeds to step S12 described later. If the motor operation command is ON (Yes in step S1), in the next step S3, it is determined whether or not the absolute value of the uv phase voltage is greater than or equal to the reference value Sv. At this time, as described above, the reference value Sv varies depending on the washing operation process, and specifically, as shown in FIG. 85V, 30V during low speed rotation (499 rpm or less), and 50V during the brake stroke.

  If the uv phase voltage is equal to or higher than the reference value Sv (Yes in step S3), the process proceeds to step S4, where it is determined whether the u phase current value (absolute value) is equal to or less than the current determination threshold value Sc. The As shown in FIG. 6, the current determination threshold value Sc is 0.5 A in the washing stroke, 0.5 A in the high-speed rotation in the dehydration stroke, 0.1 A in the low-speed rotation, and 0.1 in the brake stroke. 5A. If the current value is less than or equal to threshold value Sc (Yes in step S4), the value of the u-phase counter is incremented by 1 in step S5, and the process proceeds to step S12. If the current value is larger than threshold value Sc (No in step S4), the value of the u-phase counter does not vary and the process proceeds to step S12.

  On the other hand, when the uv phase voltage is smaller than the reference value Sv (No in step S3), the process proceeds to the next step S6, where it is determined whether or not the absolute value of the uv phase voltage is greater than or equal to the reference value Sv. Is done. If the v-w phase voltage is equal to or greater than the reference value Sv (Yes in step S6), the process proceeds to step S7, where it is determined whether the v-phase current value (absolute value) is equal to or less than the current determination threshold value Sc. The If the current value is equal to or less than threshold value Sc (Yes in step S7), the value of the v-phase counter is incremented by 1 in step S8, and the process proceeds to step S12. If the current value is larger than threshold value Sc (No in step S7), the value of the v-phase counter does not vary and the process proceeds to step S12.

  When the v-w phase voltage is smaller than the reference value Sv (No in step S6), the process proceeds to the next step S9, where it is determined whether or not the absolute value of the w-u phase voltage is greater than or equal to the reference value Sv. . If the w-u phase voltage is equal to or higher than the reference value Sv (Yes in step S9), the process proceeds to step S10, where it is determined whether the w-phase current value (absolute value) is equal to or smaller than the current determination threshold value Sc. The If the current value is equal to or smaller than threshold value Sc (Yes in step S10), the value of the w-phase counter is incremented by 1 in step S11, and the process proceeds to step S12. If the current value is larger than threshold value Sc (No in step S10), the value of the w-phase counter does not vary and the process proceeds to step S12. Even when the w-u interphase voltage is smaller than the reference value Sv (No in step S9), the process proceeds to step S12.

  In step S12, it is determined whether the counter value of each phase is 800 or more. If the value of at least one of the counters is 800 or more (Yes in step S12), the state where the current value is low continues for about 0.1 second, and the disconnection abnormality occurs in the three-phase motor 14. Determined. Then, in the next step S13, the three-phase motor 14 is stopped, the fact that an abnormality has occurred is stored in the nonvolatile memory 18, and the process ends.

  On the other hand, if the value of any counter is less than 800 (No in step S12), the process proceeds to step S14, and it is determined whether the determination time (time required for determination) exceeds the predetermined time St. The At this time, as shown in FIG. 6, the predetermined time St is set to 0.1 seconds in the washing stroke, 0.3 seconds in the dewatering stroke, and 0.3 seconds in the braking stroke. If the determination time exceeds the predetermined time St (Yes in step S14), the u, v, and w phase counters are reset in step S15, and the process returns to step S1. If the determination time is within predetermined time St (No in step S14), the process directly returns to step S1.

  As described above, according to the present embodiment, the apparatus includes the three-phase motor 14 that is driven and controlled by the inverter circuit 21, and the control circuit 17 uses the PWM duty to perform the disconnection determination process. The disconnection is determined based on detecting the current value of each phase at the timing when the line voltage between the 14 phases is equal to or higher than the reference value Sv, that is, excluding the timing when the line voltage is low. . As a result, it is possible to detect an instantaneous disconnection such as a half-contact state of the winding, and it is possible to detect the disconnection of the three-phase motor 14 reliably in a short time even in the case of low rotation.

  In addition, it is possible to eliminate the need for new addition parts or to complicate the circuit for detecting the disconnection, which can be realized at low cost. In the present embodiment, in particular, the individual line voltage predetermined value Sv, the current value threshold value Sc, and the predetermined time St are used in each of the washing process, the dehydrating process, and the braking process, and the line in the dehydrating process is used. The inter-voltage reference value Sv and the current determination threshold value Sc are varied according to the number of rotations of the three-phase motor 14. Thereby, a finer threshold value can be set, and the determination accuracy of disconnection can be further enhanced.

  In the above-described embodiment, the disconnection determination process is performed in each of the washing, dehydration, and brake strokes. However, the disconnection determination process is performed at least in the washing stroke during the washing operation stroke. In addition, it is possible to cope with an instantaneous disconnection in the washing process, and it is possible to obtain the same effect that the disconnection of the motor can be reliably detected. In this case, in a dehydration process where the rotational speed of the motor other than the washing process is relatively high, disconnection detection can be performed using another method. For example, as shown in Patent Document 1 above, a state in which one phase of the three-phase current output to the motor is equal to or smaller than a predetermined value compared to the other two-phase current values is predetermined. When it is continued for a time (5 seconds), it is possible to perform processing such as determining that a disconnection has occurred.

Further, in the above embodiment, the current value of each phase is captured at the timing when the line voltage between the phases of the three-phase motor is equal to or higher than the reference value Sv, but even if it does not depend on the line voltage, It is also possible to determine the corresponding timing by another method, and the same can be implemented. For example, in the case of vector control using a motor applied voltage, Vq or √ (Vq ² + Vd ² ) of the q-axis voltage command value Vq and the d-axis voltage command value Vd and the electrical angle in FIG. Then, when both of 110 ° to 250 ° are established, it can be configured to detect the disconnection by taking in the current value.

  In the above embodiment, the present invention is applied to the vertical type washing machine, but the present invention is not limited to the vertical type washing machine but may be a drum type washing machine or the like. In addition, the specific configuration of the washing machine and the specific numerical values used in the disconnection determination process are merely examples, and various modifications are possible. It can be implemented with appropriate changes.

  In the drawings, 1 is a washing machine, 5 is a rotating tub, 6 is a stirring body, 14 is a three-phase motor, 14u, 14v and 14w are windings, 17 is a control circuit (disconnection determination means), 18 is a nonvolatile memory, 21 Is an inverter circuit, 24u, 24v, and 24w are shunt resistors (current detection means), and 44a, 44b, and 44c are position sensors.

Claims (4)

In a washing machine that drives and controls a three-phase motor by a PWM inverter circuit and performs a washing operation by a rotational driving force generated by the three-phase motor,
Current detection means for individually detecting the phase current of the three-phase motor;
A disconnection determining means for determining disconnection of each phase winding of the three-phase motor,
The disconnection determination means is configured to set a line voltage that is equal to or higher than a reference value by the current detection means at a timing when any of the line voltages between the phases of the three-phase motor is equal to or higher than a reference value. A washing machine, wherein a disconnection is determined when a state in which a detected current value of a corresponding phase current is not more than a threshold value continues for a predetermined time.   2. The washing machine according to claim 1, wherein the disconnection determination means executes a disconnection determination process at least in a washing process during a washing operation process. The disconnection determination means uses the reference value of the individual line voltage, the threshold value of the current value, and the predetermined time in each of the washing process, the dehydration process, and the brake process in the washing operation process. The washing machine according to claim 1.   4. The disconnection determination means changes a reference value of the line voltage and a threshold value of the current value according to the number of rotations of the three-phase motor. The washing machine as described in.

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