A method and device for protecting drum washing machine from high-speed power failure

Abstract

The embodiment of the present invention provides a method and device for high-speed power-off protection of a drum washing machine. The method includes: the drum washing machine includes: a microcontroller unit, a bus capacitor, a three-phase inverter, a motor and a drum; when a fault occurs during the operation of the washing machine, causing a power-off shutdown, the three-phase inverter is controlled to be in a first working state; the voltage on the bus capacitor is detected; based on the voltage on the bus capacitor, the working state of the three-phase inverter is controlled to switch between the first working state and the second working state. The high-speed power-off protection method of the present invention, when the drum is in high-speed rotation and suddenly stops due to a fault, controls the voltage on the bus capacitor to keep the microcontroller unit in a normal working state, and effectively controls the working state of the three-phase inverter according to the voltage, so as to avoid the prior art that after the bus capacitor is protected once, the microcontroller unit is reset and exits the power-off protection state due to insufficient voltage of the bus capacitor, causing the bus capacitor to be damaged by overvoltage.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of washing machines, and more specifically, the embodiments of the present invention relate to a high-speed power-off protection method and device for a drum washing machine. Background Art

[0002] This section is intended to provide a background or context to embodiments of the invention that are recited in the claims. No description herein is admitted to be prior art by inclusion in this section.

[0003] When the washing machine is running at high speed (for example, high-speed dehydration), if the inverter board suddenly loses power, the inverter board will report a fault and shut down. When the drum of the washing machine is decelerating and shutting down, the drum of the washing machine will drive the motor to rotate. The motor is in a power generation state at this time, and the energy generated will charge the bus capacitor, causing the bus voltage to increase. When the bus capacitor voltage exceeds the preset overvoltage threshold, the control circuit on the inverter board controls the lower bridge of the three-phase inverter to directly short-circuit the brake, and the energy generated by the bus capacitor is discharged and consumed between the windings of the three-phase inverter of the motor. When the speed of the washing machine drum drops to a safe speed, the washing machine exits the high-speed power-off protection state.

[0004] The prior art has the following disadvantages: During the short-circuit braking process of the lower bridge of the three-phase inverter, the voltage on the bus capacitor will gradually decrease. When the bus voltage is lower than a certain level, the microcontroller unit (MCU) power supply circuit will work abnormally, causing the MCU to reset and stop working. If the washing machine drum is still running at a relatively high speed at this time, the energy generated will continue to charge the bus capacitor, causing the bus capacitor voltage to rise again. When the bus voltage exceeds the preset overvoltage threshold, since the MCU is in a reset state, there is no way to control the short-circuit braking of the lower bridge of the three-phase inverter to discharge the bus capacitor. The voltage on the bus capacitor will continue to rise, and when it rises to a certain level, it will cause problems such as overvoltage damage to the bus capacitor. Summary of the invention

[0005] Since the existing high-speed power-off protection technical solution has the problem that when the bus capacitor reaches the preset overvoltage threshold and the bus capacitor voltage is discharged by short-circuiting the lower bridge of the three-phase inverter, when the bus capacitor voltage is lower than a certain level, the microcontroller unit works abnormally and resets and stops working, it cannot control the high-speed operation of the drum to drive the motor to continue charging the bus capacitor, resulting in overvoltage damage to the bus capacitor. Therefore, an improved high-speed power-off protection solution is urgently needed to solve the above technical problems.

[0006] In this context, embodiments of the present invention are intended to provide a method and device for high-speed power-off protection of a drum washing machine.

[0007] In a first aspect of the embodiments of the present invention, a high-speed power-off protection method for a drum washing machine is provided, wherein the drum washing machine comprises: a microcontroller unit, a bus capacitor, a three-phase inverter, a motor and a drum;

[0008] When a fault occurs during the operation of the washing machine, causing power failure and shutdown, controlling the three-phase inverter to be in a first working state;

[0009] Detecting the voltage on the bus capacitor;

[0010] The working state of the three-phase inverter is controlled to switch between the first working state and the second working state based on the voltage on the bus capacitor.

[0011] In one embodiment of the present invention, the three-phase inverter comprises: a three-phase six-bridge-arm structure inverter circuit, wherein each bridge arm is composed of a switch tube connected in parallel with a diode, and each phase is composed of two upper and lower bridge arms connected in series, and three phases are connected in parallel to form the three-phase inverter;

[0012] The three upper bridge arms are the upper bridges of the three-phase inverter, and the three lower bridge arms are the lower bridges of the three-phase inverter;

[0013] And a connection is drawn out between the switch tubes of the upper and lower bridge arms of each phase and connected to the motor.

[0014] In another embodiment of the present invention, the first working state of the three-phase inverter is: a blocking state, that is, the six switch tubes inside the three-phase inverter are controlled to be turned off, and the bus capacitor is charged by the energy generated by the mechanical rotation of the motor;

[0015] The second working state of the three-phase inverter is a braking state, that is, the three switch tubes of the lower bridge of the three-phase inverter are controlled to be turned on, the three switch tubes of the upper bridge are turned off, and the bus capacitor is discharged.

[0016] In another embodiment of the present invention, the following steps are also included:

[0017] Comparing a first voltage on the bus capacitor with a preset overvoltage threshold;

[0018] If the first voltage is greater than or equal to the preset overvoltage threshold, controlling the three-phase inverter to be in a second working state;

[0019] If the first voltage is less than the preset overvoltage threshold, the three-phase inverter is controlled to be in a first working state.

[0020] In yet another embodiment of the present invention, the following steps are also included:

[0021] In a second working state, comparing a second voltage detected from the bus capacitor with a first voltage threshold;

[0022] If the second voltage is less than a first voltage threshold, controlling the three-phase inverter to be in a first working state;

[0023] If the second voltage is greater than or equal to the first voltage threshold, the three-phase inverter is controlled to maintain a second working state.

[0024] In yet another embodiment of the present invention, the following steps are also included:

[0025] In a first working state, the detected rotation speed of the drum is compared with a preset rotation speed threshold;

[0026] If the rotation speed of the drum is less than a preset rotation speed threshold, the drum washing machine exits the power-off protection state;

[0027] otherwise, comparing the third voltage of the bus capacitor detected with the second voltage threshold;

[0028] If the third voltage is greater than or equal to the second voltage threshold, controlling the three-phase inverter to return to the second working state;

[0029] If the third voltage is less than the second voltage threshold, controlling the three-phase inverter to remain in the first working state;

[0030] Continue to judge until the drum washing machine exits the power-off protection state.

[0031] In a second aspect of the embodiments of the present invention, a high-speed power-off protection device for a drum washing machine is provided, the drum washing machine comprising: a microcontroller unit, a bus capacitor, a three-phase inverter, a motor and a drum;

[0032] The micro control unit comprises: a control module and a detection module;

[0033] The detection module detects the voltage on the bus capacitor and the rotation speed of the drum;

[0034] The control module controls the three-phase inverter to be in a first working state when a fault occurs during the operation of the washing machine, causing power failure and shutdown; and controls the working state of the three-phase inverter to switch between the first working state and the second working state based on the voltage on the bus capacitor.

[0035] In one embodiment of the present invention, the internal structure of the three-phase inverter includes: a three-phase six-bridge-arm structure inverter circuit, wherein each bridge arm is composed of a switch tube connected in parallel with a diode, and each phase is composed of two upper and lower bridge arms connected in series, and three phases are connected in parallel to form the three-phase inverter;

[0036] The three upper bridge arms are the upper bridges of the three-phase inverter, and the three lower bridge arms are the lower bridges of the three-phase inverter;

[0037] And a connection is drawn out between the switch tubes of the upper and lower bridge arms of each phase and connected to the motor.

[0038] In another embodiment of the present invention, the first working state of the three-phase inverter is: a blocking state, that is, the control module controls the six switch tubes inside the three-phase inverter to be turned off, and the bus capacitor is charged by the energy generated by the mechanical rotation of the motor;

[0039] The second working state of the three-phase inverter is a braking state, that is, the control module controls the three switch tubes of the lower bridge of the three-phase inverter to be turned on, the three switch tubes of the upper bridge to be turned off, and the bus capacitor to be discharged.

[0040] In another embodiment of the present invention, a judgment module is further included:

[0041] Comparing a first voltage on the bus capacitor with a preset overvoltage threshold;

[0042] If the first voltage is greater than or equal to the preset overvoltage threshold, the control module controls the three-phase inverter to be in a second working state;

[0043] If the first voltage is less than the preset overvoltage threshold, the control module controls the three-phase inverter to be in a first working state.

[0044] In yet another embodiment of the present invention, the determining module further includes:

[0045] In a second working state, comparing a second voltage of the bus capacitor detected by the detection module with a first voltage threshold;

[0046] If the second voltage is less than the first voltage threshold, the control module controls the three-phase inverter to be in a first working state;

[0047] If the second voltage is greater than or equal to the first voltage threshold, the control module controls the three-phase inverter to maintain a second working state.

[0048] In yet another embodiment of the present invention, the determining module further includes:

[0049] In a first working state, comparing the rotation speed of the drum detected by the detection module with a preset rotation speed threshold;

[0050] If the rotation speed of the drum is less than a preset rotation speed threshold, the drum washing machine exits the power-off protection state;

[0051] otherwise, comparing the third voltage of the bus capacitor detected by the detection module with the second voltage threshold;

[0052] If the third voltage is greater than or equal to the second voltage threshold, the control module controls the three-phase inverter to return to the second working state;

[0053] If the third voltage is less than the second voltage threshold, the control module controls the three-phase inverter to remain in the first working state;

[0054] The judgment module continues to judge until the drum washing machine exits the power-off protection state. The high-speed power-off protection method of the present invention, when the drum is in high-speed rotation and suddenly stops due to a fault, the drum inertia drives the motor to mechanically rotate to generate energy, and by controlling the voltage on the bus capacitor, the microcontroller unit maintains a normal working state during the power-off protection process, and effectively controls the working state of the three-phase inverter according to the voltage on the bus capacitor, avoiding the prior art that after the bus capacitor is protected once, the microcontroller unit is reset and exits the power-off protection state due to insufficient bus capacitor voltage, so that the bus capacitor is recharged to exceed the overvoltage threshold, thereby damaging the bus capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which:

[0056] Figure 1 The flowchart of the prior art high-speed power-off protection method is schematically shown;

[0057] Figure 2 The flowchart of the high-speed power-off protection method of the present invention is schematically shown;

[0058] Figure 3 The internal structure diagram of a bus capacitor and a three-phase inverter is schematically shown;

[0059] Figure 4 The device of the high-speed power-off protection method of the present invention is schematically shown;

[0060] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts. DETAILED DESCRIPTION

[0061] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0062] Those skilled in the art will appreciate that the embodiments of the present invention may be implemented as a system, device, apparatus, method or computer program product. Therefore, the present disclosure may be specifically implemented in the following forms, namely: complete hardware, complete software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0063] Combine the following Figure 1 The principle of the background technology of the present invention is explained in detail.

[0064] Figure 1 This is a flow chart of the prior art high-speed power-off protection method. The specific steps are as follows:

[0065] S101, the inverter board loses power during the operation of the washing machine, and whether it is caused by a fault;

[0066] S102, when a fault occurs and causes power failure and shutdown, controlling the three-phase inverter to be in a first working state;

[0067] S103, detecting the voltage on the bus capacitor and comparing it with a preset overvoltage threshold, if the voltage is greater than or equal to the preset overvoltage threshold, executing step S104; if the voltage is less than the preset overvoltage threshold, returning to step S102;

[0068] S104, controlling the three-phase inverter to be in a second working state;

[0069] S105, detecting the rotation speed of the washing machine drum and comparing it with a preset rotation speed threshold, if the rotation speed is greater than or equal to the preset rotation speed threshold, executing step S104; if the voltage is less than the preset rotation speed threshold, exiting the high-speed power-off protection state.

[0070] As an example, in the prior art, when a drum washing machine fails during high-speed operation and causes the inverter board to lose power and shut down, the microcontroller unit controls the three-phase inverter to be in the first working state, i.e., the blocking state, to charge the capacitor.

[0071] Monitor the voltage on the capacitor in real time, and compare the measured voltage value with the preset overvoltage threshold. If the measured voltage is greater than or equal to the preset overvoltage threshold, it means that the voltage stored inside the bus capacitor has exceeded the safety range. If the bus capacitor continues to be charged, it will cause the bus capacitor to be overvoltage and damaged. Then the microcontroller controls the three-phase inverter to be in the second working state, i.e., the braking state, to discharge the capacitor. If the measured voltage is less than the preset overvoltage threshold, it means that the voltage on the bus capacitor is within the safety range and the bus capacitor can continue to be charged. Then the microcontroller controls the three-phase inverter to continue to maintain the first working state.

[0072] When the three-phase inverter is in the second working state, the microcontroller unit detects the rotation speed of the washing machine drum in real time. When the detected rotation speed of the drum is less than the preset speed threshold, it means that the energy generated by the mechanical rotation of the motor driven by the drum speed is insufficient to overcharge the voltage on the bus capacitor, and the washing machine can exit the high-speed power-off protection state.

[0073] The inventor discovered that in the existing technical solution for high-speed power-off protection, when the three-phase inverter is controlled to be in the second working state, the bus capacitor power generation voltage is reduced. When the voltage on the bus capacitor is reduced to a certain level, the micro-control unit is reset and stops working due to abnormal operation of the power supply circuit. At this time, the micro-control unit cannot play a monitoring role and cannot detect the voltage on the bus capacitor and control the state of the three-phase inverter. The micro-control unit only provides a one-time protection for the bus capacitor. After the micro-control unit is reset, it cannot control the working state of the three-phase inverter. If the drum still drives the motor to rotate at high speed at this time, the energy generated by the mechanical movement of the motor will all be used to charge the bus capacitor, which will cause overvoltage damage to the bus capacitor.

[0074] In order to overcome the existing technical problems, the present invention proposes a high-speed power-off protection method and device for a drum washing machine.

[0075] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention. In this article, it should be understood that the preset overvoltage threshold, the preset speed threshold, the preset first voltage threshold and the preset second voltage threshold are manually settable. In addition, any number of elements in the drawings is for illustration rather than limitation, and any naming is only for distinction and does not have any limiting meaning.

[0076] Reference below Figure 2 The following describes a high-speed power-off protection method for a drum washing machine according to an exemplary embodiment of the present invention. It should be noted that the above application scenarios are only shown to facilitate understanding of the spirit and principle of the present invention, and the embodiments of the present invention are not limited in this regard. On the contrary, the embodiments of the present invention can be applied to any applicable scenario.

[0077] like Figure 2 As shown, the high-speed power-off protection method of the embodiment of the present invention at least includes:

[0078] S201, the inverter board loses power during the operation of the washing machine, and whether it is caused by a fault;

[0079] S202, when a fault occurs and causes power failure and shutdown, controlling the three-phase inverter to be in a first working state;

[0080] S203, detecting the voltage on the bus capacitor and comparing it with a preset overvoltage threshold, if the voltage is greater than or equal to the preset overvoltage threshold, executing step S204; if the voltage is less than the preset overvoltage threshold, returning to step S202;

[0081] S204, controlling the three-phase inverter to be in a second working state;

[0082] S205, in the second working state, detecting the voltage on the bus capacitor and comparing it with the preset first voltage threshold, if the voltage is greater than or equal to the preset first voltage threshold, returning to step S204; if the voltage is less than the preset first voltage threshold, executing step S206;

[0083] S206, controlling the three-phase inverter to be in a first working state;

[0084] S207, in the first working state, the detected rotation speed of the drum is compared with a preset rotation speed threshold, and if the rotation speed of the drum is less than the preset rotation speed threshold, the drum washing machine exits the power-off protection state;

[0085] Otherwise, execute step S208, compare the detected bus capacitance with the second voltage threshold, and if the voltage is greater than or equal to the second voltage threshold, return to step S204;

[0086] If the voltage is less than the second voltage threshold, return to step S206.

[0087] As an example, combining Figure 3 The internal structure diagram of a bus capacitor and a three-phase inverter used in the present invention is shown in the figure: the bus capacitor 313 is connected in parallel with the three-phase inverter 314. The three-phase inverter includes: six switch tubes 301-306 and six diodes 307-312. The three-phase six-bridge arm structure inverter circuit, the three phases are connected in parallel to form a three-phase inverter. The switch tube 301 and the diode 307 are connected in parallel to form the upper bridge arm, the switch tube 304 and the switch tube 310 are connected in parallel to form the lower bridge arm, and the upper and lower bridge arms are connected in series to form one phase of the three-phase inverter. The other two phases of the three-phase inverter are the same and will not be described here. The three upper bridge arms are the upper bridges of the three-phase inverter, and the three lower bridge arms are the lower bridges of the three-phase inverter. And a wiring is drawn between the switch tubes of the upper and lower bridge arms of each phase to connect to the one-phase coil of the motor.

[0088] When the power is off due to a fault, the microcontroller controls the six switches inside the three-phase inverter to turn off, and the energy generated by the mechanical rotation of the motor driven by the inertia of the drum is used to charge the bus capacitor to the first working state of the three-phase inverter, i.e. the blocking state. The microcontroller controls the three switches on the lower bridge of the three-phase inverter to turn on, and the three switches on the upper bridge to turn off, and the bus capacitor is discharged to the second working state of the three-phase inverter, i.e. the braking state.

[0089] When the drum washing machine fails during high-speed operation and the inverter board loses power and stops, the microcontroller unit controls the three-phase inverter to be in the first working state, i.e., the locked state. The microcontroller unit controls the six switching tubes inside the three-phase inverter to be turned off, and the energy generated by the mechanical rotation of the motor is used to charge the capacitor.

[0090] Monitor the voltage on the capacitor in real time, and compare the measured voltage value with the preset overvoltage threshold. If the measured voltage is greater than or equal to the preset overvoltage threshold, it means that the voltage stored inside the bus capacitor has exceeded the safety range. If the bus capacitor continues to be charged, the bus capacitor will be damaged by overvoltage. Then the microcontroller controls the three-phase inverter to be in the second working state, i.e., the braking state, and controls the three switches of the lower bridge of the three-phase inverter to be turned on and the three switches of the upper bridge to be turned off, so that the capacitor is discharged. If the measured voltage is less than the preset overvoltage threshold, it means that the voltage on the bus capacitor is within the safety range and the bus capacitor can continue to be charged. Then the microcontroller controls the three-phase inverter to continue to remain in the first working state. For example: the three-phase inverter is in the first working state, and the charging voltage of the bus capacitor gradually increases. Assuming that the preset overvoltage threshold is 440V, if the measured voltage on the bus capacitor is 450V, which is greater than the preset overvoltage threshold of 440V, it means that the voltage charged on the bus capacitor has exceeded the safety range. If the bus capacitor continues to be charged, it will cause the bus capacitor to be overvoltage and damaged. In this case, the three-phase inverter is controlled to switch to the second working state to discharge the bus capacitor. If the measured voltage on the bus capacitor is 300V, which is less than the preset overvoltage threshold of 440V, it means that the voltage on the bus capacitor is within the safety range and can continue to be charged. In this case, the three-phase inverter is controlled to remain in the first working state.

[0091] When the three-phase inverter is in the second working state, the bus capacitor discharges and causes the voltage to decrease. The voltage on the bus capacitor is detected in real time and compared with the preset first voltage threshold. If the voltage on the bus capacitor is greater than the preset first voltage threshold, it means that the voltage on the bus capacitor at this time can still continue to supply power to the micro control unit so that the micro control unit circuit works normally, then the micro control unit controls the three-phase inverter to continue to maintain the second working state and continue to control the bus capacitor discharge. If the voltage on the bus capacitor is less than the first voltage threshold, it means that if the voltage on the bus capacitor continues to decrease, the micro control unit will reset and stop working, then the micro control unit will control the three-phase inverter to switch to the first working state to charge the bus capacitor. For example: assuming that the preset first voltage threshold is 160V, if the voltage on the bus capacitor is detected to be 150V less than the preset first voltage threshold 160V, it means that if the voltage on the bus capacitor continues to decrease, it will cause the micro control unit to stop working, then the micro control unit controls the three-phase inverter to switch to the first working state to charge the bus capacitor. If it is detected that the capacitance of the bus capacitor is 180V which is greater than the preset first voltage threshold 160V, it means that the voltage of the bus capacitor is sufficient for the micro control unit to work normally, then the micro control unit controls the three-phase inverter to continue to maintain the second working state.

[0092] When the three-phase inverter is in the first working state, the bus capacitor is charged, resulting in a voltage increase. First, the speed of the drum is measured in real time and compared with the preset speed threshold. If the actual speed of the drum measured is less than the preset speed threshold, it means that the speed of the drum is already within the safe range, that is, the energy generated by the motor rotation caused by the inertia of the drum will not affect or damage the components inside the washing machine, and the microcontroller unit controls the washing machine to exit the high-speed power-off protection state. If the actual speed of the drum measured is greater than the preset speed threshold, the voltage on the bus capacitor needs to be detected and compared with the preset second voltage threshold. If the voltage on the bus capacitor is greater than the preset second voltage threshold, it means that the voltage on the bus capacitor at this time can still continue to supply power to the microcontroller unit to make its circuit work normally, but in order to consume the energy converted by the mechanical rotation of the motor caused by the inertia of the drum, when the voltage on the bus capacitor is greater than the second voltage threshold, the bus capacitor needs to be controlled to discharge, and the microcontroller unit controls the three-phase inverter in the second working state. If the voltage on the bus capacitor is less than the second voltage threshold, the microcontroller unit will control the three-phase inverter to continue to remain in the first working state to charge the bus capacitor.

[0093] The microcontroller controls the voltage on the bus capacitor to fluctuate between a preset first voltage threshold and a preset second voltage threshold by controlling the working state of the three-phase inverter, thereby ensuring the normal operation of the microcontroller while consuming the energy converted from the mechanical rotation of the motor due to the inertia of the drum, thereby achieving high-speed power-off protection.

[0094] For example: the preset speed threshold of the drum is 20 rpm. If the actual drum speed is measured to be 18 rpm, it means that the energy generated by the drum driving the motor to rotate will not affect or damage the components inside the washing machine, and the microcontroller unit controls the washing machine to exit the high-speed power-off protection state. If the actual drum speed is measured to be 30 rpm, it means that the drum speed is too large and the energy generated by the motor rotation will damage the components of the washing machine, so high-speed power-off protection is required. Assuming that the predetermined second voltage threshold is 200V, if the voltage on the bus capacitor is detected to be 180V less than the preset second voltage threshold of 200V, it means that the voltage on the bus capacitor can continue to increase, and the microcontroller unit controls the three-phase inverter to continue to maintain the first working state to charge the bus capacitor. If the voltage on the bus capacitor is detected to be 220V greater than the preset second voltage threshold of 200V, it means that the voltage on the bus capacitor is sufficient to provide energy for the normal operation of the microcontroller unit, and in order to consume the energy generated by the drum driving the motor to rotate mechanically due to inertia, the microcontroller unit controls the three-phase inverter to switch to the second working state to discharge the bus capacitor.

[0095] The advantages of the present invention over the background technology are as follows: when the drum is rotating at high speed and suddenly fails and stops, the inertia of the drum drives the motor to mechanically rotate and generate energy, and the voltage on the bus capacitor is controlled to keep the microcontroller unit in normal working state during the power-off protection process, and the working state of the three-phase inverter is effectively controlled according to the voltage on the bus capacitor, thereby avoiding the situation in the prior art where the microcontroller unit is reset and exits the power-off protection state due to insufficient voltage of the bus capacitor after a one-time protection of the bus capacitor, so that the bus capacitor is recharged to exceed the overvoltage threshold, thereby damaging the bus capacitor.

[0096] After introducing the method of the exemplary embodiment of the present invention, next, refer to Figure 4 A high-speed power-off protection device for a drum washing machine according to an exemplary embodiment of the present invention is provided. Figure 4 As shown, the high-speed power-off protection device for a drum washing machine includes: a microcontroller unit 401, a three-phase inverter 403, a motor 404 and a drum 405. The connection method is as follows:

[0097] The micro control unit 401 is connected to the bus capacitor 402, the three-phase inverter 403, the motor 404 and the drum 405 respectively, and is used to detect the voltage on the bus capacitor 402, the rotation speed of the motor 404 and the drum 405, and control the working state of the three-phase inverter 403 according to the voltage on the bus capacitor 402;

[0098] The roller 405 is connected to the motor 404 via a transmission device, and is used to drive the motor 404 to rotate and generate energy by utilizing inertia;

[0099] The three-phase inverter 403 repeatedly consumes the energy converted by the mechanical rotation of the motor 404;

[0100] The bus capacitor 402 is connected in parallel with the three-phase inverter 403 to store part of the energy generated by the motor and provide energy required for the micro control unit 401 to operate normally.

[0101] The micro control unit 401 further includes: a control module 406 , a detection module 407 and a judgment module 408 .

[0102] The detection module 407 detects the capacitance on the bus capacitor 402 and the rotation speed of the drum 405 .

[0103] The judgment module 408, when executing step S201, judges whether the washing machine has a fault that causes the inverter board to lose power during the operation of the washing machine; when executing step S203, judges whether the capacitance on the bus capacitor 402 detected by the detection module 407 exceeds the preset overvoltage threshold; when executing S205, judges whether the capacitance on the bus capacitor 402 detected by the detection module 407 can provide sufficient energy to enable the microcontroller unit to work normally; when executing S207, judges whether the rotation speed of the drum 405 detected by the detection module 407 is within a safe range; when executing S208, judges whether the capacitance on the bus capacitor 402 detected by the detection module 407 is greater than the preset second voltage threshold.

[0104] The control module 406 controls the three-phase inverter 403 to be in the first working state when a fault occurs during the operation of the washing machine, causing power failure and shutdown; and controls the working state of the three-phase inverter 403 to switch between the first working state and the second working state based on the judgment result of the judgment module 408 and the voltage on the bus capacitor 402.

[0105] As an example, combining Figure 3 The internal structure diagram of a bus capacitor and a three-phase inverter used in the present invention is shown in the figure: the bus capacitor 313 is connected in parallel with the three-phase inverter 314. The three-phase inverter includes: six switch tubes 301-306 and six diodes 307-312. The three-phase six-bridge arm structure inverter circuit, the three phases are connected in parallel to form a three-phase inverter. The switch tube 301 and the diode 307 are connected in parallel to form the upper bridge arm, the switch tube 304 and the switch tube 310 are connected in parallel to form the lower bridge arm, and the upper and lower bridge arms are connected in series to form one phase of the three-phase inverter. The other two phases of the three-phase inverter are the same and will not be described here. The three upper bridge arms are the upper bridges of the three-phase inverter, and the three lower bridge arms are the lower bridges of the three-phase inverter. And a wiring is drawn between the switch tubes of the upper and lower bridge arms of each phase to connect to the one-phase coil of the motor.

[0106] When the power is off due to a fault, the control module 406 controls the six switch tubes inside the three-phase inverter 403 to be turned off, and the energy generated by the mechanical rotation of the motor 404 driven by the inertia of the drum 405 is used to charge the bus capacitor 402 to the first working state of the three-phase inverter 403, i.e., the blocking state. The control module 406 controls the three switch tubes of the lower bridge of the three-phase inverter to be turned on, and the three switch tubes of the upper bridge to be turned off, and the bus capacitor 402 is discharged to the second working state of the three-phase inverter 403, i.e., the braking state.

[0107] After the drum washing machine fails during high-speed operation and causes the inverter board to lose power and shut down, the control module 406 controls the three-phase inverter 403 to be in the first working state, i.e., the locked state. The control module 406 controls the six switching tubes inside the three-phase inverter 403 to be closed, and the energy generated by the mechanical rotation of the motor 404 is used to charge the bus capacitor 402.

[0108] The voltage on the bus capacitor 402 is monitored in real time, and the judgment module 408 compares the voltage value measured by the detection module 407 with the preset overvoltage threshold. If the judgment result is that the measured voltage is greater than or equal to the preset overvoltage threshold, it means that the voltage stored in the bus capacitor 402 has exceeded the safety range at this time. If the bus capacitor 402 is continuously charged, the bus capacitor 402 will be damaged by overvoltage. Then the execution control module 406 controls the three-phase inverter 403 to be in the second working state, i.e., the braking state. The control module 406 controls the three switches of the lower bridge of the three-phase inverter 403 to be turned on, and the three switches of the upper bridge are disconnected, and the capacitor is discharged. If the judgment result is that the measured voltage is less than the preset overvoltage threshold, it means that the voltage on the bus capacitor 402 is within the safety range at this time, and the bus capacitor 402 can continue to be charged. Then the control module 406 controls the three-phase inverter 403 to continue to remain in the first working state. For example: the three-phase inverter 403 is in the first working state, and the charging voltage of the bus capacitor 402 gradually increases. Assuming that the preset overvoltage threshold is 440V, if the measured voltage on the bus capacitor 402 is 450V, which is greater than the preset overvoltage threshold 440V, it means that the voltage charged on the bus capacitor 402 has exceeded the safety range. If the bus capacitor 402 continues to be charged, the bus capacitor 402 will be damaged by overvoltage. Then the control module 406 controls the three-phase inverter 403 to switch to the second working state, so that the bus capacitor 402 is discharged. If the measured voltage on the bus capacitor 402 is 300V, which is less than the preset overvoltage threshold 440V, it means that the voltage on the bus capacitor is within the safety range and can continue to be charged. Then the control module 406 controls the three-phase inverter 403 to remain in the first working state.

[0109] When the three-phase inverter 403 is in the second working state, the bus capacitor 402 discharges, resulting in a voltage drop. The detection module 407 detects the voltage on the bus capacitor 402 in real time, and the judgment module 408 compares it with the preset first voltage threshold. If the judgment result shows that the voltage on the bus capacitor 402 is greater than the preset first voltage threshold, it means that the voltage on the bus capacitor 402 at this time can still continue to supply power to the micro control unit 401 so that the micro control unit 401 circuit works normally, then the control module 406 controls the three-phase inverter 403 to remain in the second working state and continue to control the bus capacitor 402 to discharge. If the judgment result shows that the voltage on the bus capacitor 402 is less than the first voltage threshold, it means that if the voltage on the bus capacitor 402 continues to decrease, the micro control unit 401 will reset and stop working, then the control module 406 will control the three-phase inverter 403 to switch to the first working state to charge the bus capacitor 402. For example: Assuming that the preset first voltage threshold is 160V, if the voltage on the bus capacitor is detected to be 150V, which is less than the preset first voltage threshold 160V, it means that if the voltage on the bus capacitor continues to decrease, the micro control unit will stop working, and the micro control unit controls the three-phase inverter to switch to the first working state to charge the bus capacitor. If the capacitance on the bus capacitor is detected to be 180V, which is greater than the preset first voltage threshold 160V, it means that the voltage on the bus capacitor is sufficient for the micro control unit to work normally, and the micro control unit controls the three-phase inverter to continue to remain in the second working state.

[0110] When the three-phase inverter 403 is in the first working state, the bus capacitor 402 is charged, resulting in a voltage increase. First, the judgment module 408 detects the actual speed of the drum 405 detected by the detection module 407 and compares it with the preset speed threshold. If the judgment result is that the measured actual speed of the drum is less than the preset speed threshold, it means that the speed of the drum 405 is already within the safe range, that is, the energy generated by the rotation of the motor 404 due to the inertia of the drum 405 will not affect or damage the components inside the washing machine, then the micro control unit 401 controls the washing machine to exit the high-speed power-off protection state. If the judgment result is that the measured actual rotation speed of the drum is greater than the preset rotation speed threshold, the judgment module 408 will detect the voltage on the bus capacitor 402 by the detection module 407 and compare it with the preset second voltage threshold. If the judgment result is that the voltage on the bus capacitor 402 is greater than the preset second voltage threshold, it means that the voltage on the bus capacitor 402 at this time can still continue to supply power to the micro control unit 401 to make its circuit work normally, but in order to consume the energy converted by the mechanical rotation of the motor 404 caused by the inertia of the drum 405, when the voltage on the bus capacitor 402 is greater than the second voltage threshold, the control module 406 needs to control the bus capacitor 402 to discharge, and the control module 406 controls the three-phase inverter to be in the second working state. If the judgment result is that the voltage on the bus capacitor 402 is less than the second voltage threshold, the control module 406 will control the three-phase inverter to continue to remain in the first working state to charge the bus capacitor.

[0111] The microcontroller unit 401 controls the voltage on the bus capacitor 402 to fluctuate between a preset first voltage threshold and a preset second voltage threshold by controlling the working state of the three-phase inverter 403, thereby ensuring the normal operation of the microcontroller unit 401 while consuming the energy converted from the mechanical rotation of the motor 404 due to the inertia of the roller 405, thereby achieving high-speed power-off protection.

[0112] For example: the preset speed threshold of the drum is 20 rpm. If the actual drum speed is measured to be 18 rpm, it means that the energy generated by the drum driving the motor to rotate will not affect or damage the components inside the washing machine, and the microcontroller unit controls the washing machine to exit the high-speed power-off protection state. If the actual drum speed is measured to be 30 rpm, it means that the drum speed is too large and the energy generated by the motor rotation will damage the components of the washing machine, so high-speed power-off protection is required. Assuming that the predetermined second voltage threshold is 200V, if the voltage on the bus capacitor is detected to be 180V less than the preset second voltage threshold of 200V, it means that the voltage on the bus capacitor can continue to increase, and the microcontroller unit controls the three-phase inverter to continue to maintain the first working state to charge the bus capacitor. If the voltage on the bus capacitor is detected to be 220V greater than the preset second voltage threshold of 200V, it means that the voltage on the bus capacitor is sufficient to provide energy for the normal operation of the microcontroller unit, and in order to consume the energy generated by the drum driving the motor to rotate mechanically due to inertia, the microcontroller unit controls the three-phase inverter to switch to the second working state to discharge the bus capacitor.

[0113] It should be noted that although several units / modules or sub-units / modules of the drum washing machine high-speed power-off protection device are mentioned in the above detailed description, this division is only exemplary and not mandatory. In fact, according to an embodiment of the present invention, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided into multiple units / modules for embodiment.

[0114] In addition, although the operations of the method of the present invention are described in a specific order in the drawings, this does not require or imply that the operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0115] Although the spirit and principle of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined to benefit, and such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the attached claims.

Claims

1. A high-speed power-off protection method for a drum washing machine, characterized in that The drum washing machine comprises: a micro control unit, a bus capacitor, a three-phase inverter, a motor and a drum; The three-phase inverter comprises: a three-phase six-bridge-arm structure inverter circuit, wherein each bridge arm is composed of a switch tube connected in parallel with a diode, and each phase is composed of two upper and lower bridge arms connected in series, and three phases are connected in parallel to form the three-phase inverter; The three upper bridge arms are the upper bridges of the three-phase inverter, and the three lower bridge arms are the lower bridges of the three-phase inverter; A connection is drawn between the switch tubes of the upper and lower bridge arms of each phase and connected to the motor; The first working state of the three-phase inverter is: a blocking state, that is, the six switch tubes inside the three-phase inverter are controlled to be turned off, and the bus capacitor is charged by the energy generated by the mechanical rotation of the motor; The second working state of the three-phase inverter is: braking state, that is, the three switches of the lower bridge of the three-phase inverter are controlled to be turned on, the three switches of the upper bridge are turned off, and the bus capacitor is discharged; When a fault occurs during the operation of the washing machine, causing power failure and shutdown, controlling the three-phase inverter to be in a first working state; Detecting the voltage on the bus capacitor; The working state of the three-phase inverter is controlled to switch between the first working state and the second working state based on the voltage on the bus capacitor.

2. The method according to claim 1, characterized in that The following steps are also included: Comparing a first voltage on the bus capacitor with a preset overvoltage threshold; If the first voltage is greater than or equal to the preset overvoltage threshold, controlling the three-phase inverter to be in a second working state; If the first voltage is less than the preset overvoltage threshold, the three-phase inverter is controlled to be in a first working state.

3. The method according to claim 2, characterized in that The following steps are also included: In a second working state, comparing a second voltage detected from the bus capacitor with a first voltage threshold; If the second voltage is less than a first voltage threshold, controlling the three-phase inverter to be in a first working state; If the second voltage is greater than or equal to the first voltage threshold, the three-phase inverter is controlled to maintain a second working state.

4. The method according to claim 3, characterized in that The following steps are also included: In a first working state, the detected rotation speed of the drum is compared with a preset rotation speed threshold; If the rotation speed of the drum is less than a preset rotation speed threshold, the drum washing machine exits the power-off protection state; otherwise, comparing the third voltage of the bus capacitor detected with the second voltage threshold; If the third voltage is greater than or equal to the second voltage threshold, controlling the three-phase inverter to return to the second working state; If the third voltage is less than the second voltage threshold, controlling the three-phase inverter to remain in the first working state; Continue to judge until the drum washing machine exits the power-off protection state.

5. A high-speed power-off protection device for a drum washing machine, characterized in that The drum washing machine comprises: a micro control unit, a bus capacitor, a three-phase inverter, a motor and a drum; The micro control unit comprises: a control module and a detection module; The internal structure of the three-phase inverter includes: a three-phase six-bridge-arm structure inverter circuit, wherein each bridge arm is composed of a switch tube connected in parallel with a diode, and each phase is composed of two upper and lower bridge arms connected in series, and three phases are connected in parallel to form the three-phase inverter; The three upper bridge arms are the upper bridges of the three-phase inverter, and the three lower bridge arms are the lower bridges of the three-phase inverter; A connection is drawn between the switch tubes of the upper and lower bridge arms of each phase and connected to the motor; The first working state of the three-phase inverter is: a blocking state, that is, the control module controls the six switch tubes inside the three-phase inverter to be turned off, and the bus capacitor is charged by the energy generated by the mechanical rotation of the motor; The second working state of the three-phase inverter is: braking state, that is, the control module controls the three switch tubes of the lower bridge of the three-phase inverter to be turned on, the three switch tubes of the upper bridge to be turned off, and the bus capacitor to be discharged; The detection module detects the voltage on the bus capacitor and the rotation speed of the drum; The control module controls the three-phase inverter to be in a first working state when a fault occurs during the operation of the washing machine, causing power failure and shutdown; and controls the working state of the three-phase inverter to switch between the first working state and the second working state based on the voltage on the bus capacitor.

6. The device according to claim 5, characterized in that It also includes the judgment module: Comparing a first voltage on the bus capacitor with a preset overvoltage threshold; If the first voltage is greater than or equal to the preset overvoltage threshold, the control module controls the three-phase inverter to be in a second working state; If the first voltage is less than the preset overvoltage threshold, the control module controls the three-phase inverter to be in a first working state.

7. The device according to claim 6, characterized in that The judging module further includes: In a second working state, comparing a second voltage of the bus capacitor detected by the detection module with a first voltage threshold; If the second voltage is less than the first voltage threshold, the control module controls the three-phase inverter to be in a first working state; If the second voltage is greater than or equal to the first voltage threshold, the control module controls the three-phase inverter to maintain a second working state.

8. The device according to claim 7, characterized in that The judging module further includes: In a first working state, comparing the rotation speed of the drum detected by the detection module with a preset rotation speed threshold; If the rotation speed of the drum is less than a preset rotation speed threshold, the drum washing machine exits the power-off protection state; otherwise, comparing the third voltage of the bus capacitor detected by the detection module with the second voltage threshold; If the third voltage is greater than or equal to the second voltage threshold, the control module controls the three-phase inverter to return to the second working state; If the third voltage is less than the second voltage threshold, the control module controls the three-phase inverter to remain in the first working state; The determination module continues to determine until the drum washing machine exits the power-off protection state.

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