Household appliances and their driving circuits

Abstract

The present invention discloses a household appliance and a drive circuit thereof, which includes a voltage conversion unit, a zero-crossing detection unit, a micro-control unit, a variable frequency drive unit and a current sampling unit; the voltage conversion unit is connected to an AC power supply, and is used to reduce the voltage of the AC power input by the AC power supply, and convert the reduced AC power into DC power with multiple voltage levels; the output end of the voltage conversion unit includes an AC output end, a second DC output end and a third DC output end; the zero-crossing detection unit is used to detect the zero-crossing moment of the voltage at the AC output end; the current sampling unit is used to detect the current when the load is working; the variable frequency drive unit is used to adjust the speed of the load according to the zero-crossing moment of the voltage at the AC output end and the current when the load is working; the second DC output end is connected to the power supply end of the variable frequency drive unit for power supply; and the third DC output end is connected to the power supply end of the zero-crossing detection unit, the micro-control unit and the current sampling unit for power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of household appliances, and in particular to a driving circuit for household appliances and a household appliance. Background Art

[0002] Applying frequency conversion technology to range hoods allows them to adjust the motor speed based on flue pressure, thereby overcoming flue resistance and smoothly exhausting oil smoke and exhaust gases outdoors. Motors are categorized as DC and AC motors based on the nature of their power supply. DC motors have the advantage of a wide adjustable speed range, making them suitable for high-resistance flue conditions. However, they have the disadvantage of higher drive circuit costs for controlling DC motors. While AC motors have lower drive circuit costs, existing AC motor frequency conversion solutions primarily rely on detecting the zero-crossing signal of the mains to control the conduction of thyristors. This method can easily result in voltage waveform loss, leading to excessive power supply harmonics. Summary of the Invention

[0003] In order to solve the above technical problems, the first aspect of the present invention provides a driving circuit for household appliances, which achieves the purpose of changing the load speed by changing the amplitude of the load working power supply, and while achieving adjustable load speed, it can effectively maintain the integrity of the sinusoidal wave of the load working power supply.

[0004] A second aspect of the present invention provides a household appliance.

[0005] To achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0006] According to a first aspect of the present invention, there is provided a driving circuit for a household appliance, comprising a voltage conversion unit, a zero-crossing detection unit, a micro-control unit, a variable frequency drive unit, and a current sampling unit;

[0007] The voltage conversion unit is connected to the AC power supply and is used to reduce the voltage of the AC power input by the AC power supply and convert the reduced AC power into DC power with multiple voltage levels; the output end of the voltage conversion unit includes an AC output end, a second DC output end and a third DC output end;

[0008] The zero-crossing detection unit is used to detect the zero-crossing moment of the voltage of the AC output end; the input end of the zero-crossing detection unit is connected to the AC output end, and the output end is connected to the micro-control unit;

[0009] The current sampling unit is used to detect the current when the load is working; the input end of the current sampling unit is connected to the live wire of the AC power supply, and the output end is connected to the micro-control unit;

[0010] The variable frequency drive unit is used to adjust the speed of the load according to the zero-crossing moment of the voltage at the AC output end and the current of the load when the load is working; the control signal input end of the variable frequency drive unit is connected to the micro-control unit, the signal input end of the variable frequency drive unit is connected to the live wire of the AC power supply, and the signal output end of the variable frequency drive unit is connected to the load;

[0011] The second DC output terminal is connected to the power supply terminal of the variable frequency drive unit for power supply; the third DC output terminal is connected to the power supply terminals of the zero-crossing detection unit, the micro-control unit and the current sampling unit for power supply.

[0012] According to some embodiments of the present invention, the voltage conversion unit includes an AC step-down branch, a rectifier branch, a filter branch, a first DC step-down branch and a second DC step-down branch; the input end of the AC step-down branch is connected to the AC power supply, and the output end of the AC step-down branch serves as the AC output end; the input end of the rectifier branch is connected to the output end of the AC step-down branch; the input end of the filter branch is connected to the output end of the rectifier branch, and the output end of the filter branch serves as the first DC output end; the input end of the first DC step-down branch is connected to the output end of the filter branch, and the output end of the first DC step-down branch serves as the second DC output end; the input end of the second DC step-down branch is connected to the output end of the first DC step-down branch, and the output end of the second DC step-down branch serves as the third DC output end.

[0013] According to some embodiments of the present invention, the AC step-down branch includes a transformer; the first pin of the primary winding of the transformer is connected to the live wire of the AC power supply, and the second pin of the primary winding of the transformer is connected to the neutral wire of the AC power supply; the secondary winding of the transformer is connected to the input end of the rectifier branch as the AC output end, and the secondary winding of the transformer is connected to the input end of the zero-crossing detection unit.

[0014] According to some embodiments of the present invention, the zero-crossing detection unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, an optocoupler, a fourth diode, a fifth diode and a fifth transistor; the anode of the fifth diode is connected to the AC output end, and the cathode of the fifth diode is connected to the base of the fifth transistor through the third resistor; the emitter of the fifth transistor is connected to the anode of the fifth diode, and the collector of the fifth transistor is connected to the cathode of the optocoupler input end; the anode of the optocoupler input end is connected in series to the cathode of the fifth diode through the first resistor and the second resistor; the anode of the fourth diode is connected to the AC output end, and the cathode of the fourth diode is connected to the common node between the first resistor and the second resistor; the emitter of the optocoupler output end is grounded; the collector of the optocoupler output end is connected to the third DC output end through the fourth resistor, and the collector of the optocoupler output end is connected to the micro-control unit.

[0015] According to some embodiments of the present invention, the variable frequency drive unit includes a control branch and a switch branch; the control signal input end of the control branch is connected to the micro-control unit, and the output end of the control branch is connected to the switch branch; the signal input end of the switch branch is connected to the live wire of the AC power supply, and the signal output end of the switch branch is connected to the load; the control branch controls the on and off of the switch branch according to the output signal of the micro-control unit.

[0016] According to some embodiments of the present invention, the control branch includes a first diode, a twelfth resistor and a control module; the anode of the first diode is connected to the second DC output end, the cathode of the first diode is connected to the first end of the control module, the micro-control unit is connected to the second end of the control module through the twelfth resistor, the third end of the control module is grounded, and the first end, the fourth end and the fifth end of the control module are connected to the switch branch.

[0017] According to some embodiments of the present invention, the control module includes a first triode, a second triode, a third triode, a fourth triode, a ninth resistor, a tenth resistor, an eleventh resistor, a thirteenth resistor, a fourteenth resistor and a seventh diode; the emitter of the third triode is connected to the cathode of the first diode as the first end of the control module; the emitter of the third triode is connected to the base of the third triode through the tenth resistor, the base of the third triode is connected to the collector of the fourth triode through the eleventh resistor, the base of the fourth triode is connected to one end of the twelfth resistor as the second end of the control module; the base of the fourth triode is connected to the collector of the fourth triode through the eleventh resistor The thirteenth resistor is grounded, and the emitter of the fourth transistor is grounded through the fourteenth resistor; the anode of the seventh diode is grounded, and the anode of the seventh diode serves as the third end of the control module; the cathode of the seventh diode is connected to the collector of the second transistor, and the collector of the second transistor serves as the fourth end of the control module; the collector of the second transistor is connected to the base of the second transistor through the ninth resistor, and the base of the second transistor is connected to the collector of the third transistor and the base of the first transistor; the emitter of the second transistor is connected to the emitter of the first transistor, and the collector of the first transistor serves as the fifth end of the control module.

[0018] According to some embodiments of the present invention, the switching branch includes a transistor, a first capacitor, a seventh capacitor, a seventh resistor and an eighth resistor; the drain of the transistor is connected to the live wire of the AC power supply; the source of the transistor is connected to one end of the connection terminal of the load as the signal output end of the variable frequency drive unit, and the other end of the connection terminal of the load is connected to the neutral wire of the AC power supply; the gate of the transistor is connected to the control branch through the eighth resistor; the seventh resistor and the seventh capacitor are connected in parallel between the gate and source of the transistor; one end of the first capacitor is connected to the control branch, the other end of the first capacitor is connected to the control branch, and the other end of the first capacitor is connected to the source of the transistor.

[0019] According to some embodiments of the present invention, the current sampling unit includes a current transformer, an operational amplifier, a fifth resistor, a sixth resistor, a fifteenth resistor, a sixteenth resistor and a seventeenth resistor; the coil of the current transformer is sleeved on the live wire of the AC power supply; the first output pin of the current transformer is connected to the second output pin of the current transformer through the fifteenth resistor; the second output pin of the current transformer is connected to the negative input pin of the operational amplifier through the sixth resistor; the first output pin of the current transformer is connected to the positive input pin of the operational amplifier through the sixteenth resistor; the negative input pin of the operational amplifier is connected to the output pin of the operational amplifier through the fifth resistor; the positive input pin of the operational amplifier is grounded through the seventeenth resistor; the ground pin of the operational amplifier is grounded; the power pin of the operational amplifier is connected to the third DC output end; the output pin of the operational amplifier is connected to one end of the fifth resistor and then connected to the micro-control unit as the output end of the current sampling unit.

[0020] A household appliance according to an embodiment of a second aspect of the present invention includes a driving circuit of the household appliance as described in any embodiment of the first aspect.

[0021] The drive circuit for household appliances according to embodiments of the present invention has at least the following beneficial effects: The load's operating state is controlled by controlling the connection and disconnection between the live wire of the AC power supply and the signal output terminal of the variable frequency drive unit. This means that the load's speed is varied by changing the amplitude of the load's operating power supply. While achieving adjustable load speed, the integrity of the AC power supply's sinusoidal wave is maintained, thereby avoiding the generation of harmonics. The use of the drive circuit for household appliances in accordance with the above technical solution is beneficial for improving the reliability of the household appliances and reducing development costs.

[0022] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0024] Figure 1 is a structural block diagram of a driving circuit according to an embodiment of the present invention;

[0025] Figure 2 1 is a circuit schematic diagram of a voltage conversion unit and a zero-crossing detection unit according to an embodiment of the present invention;

[0026] Figure 3 This is a timing diagram of zero-crossing detection according to an embodiment of the present invention;

[0027] Figure 4 1 is a circuit diagram of a variable frequency drive unit according to an embodiment of the present invention;

[0028] Figure 5 This is a current flow diagram when a high level is input to the control signal input terminal of the variable frequency drive unit according to an embodiment of the present invention;

[0029] Figure 6 This is a current flow diagram when a low level is input to the control signal input terminal of the variable frequency drive unit according to an embodiment of the present invention;

[0030] Figure 7 is a circuit schematic diagram of a current sampling unit according to an embodiment of the present invention;

[0031] Figure 8 2 is a diagram showing the principle of adjusting the load speed according to an embodiment of the present invention.

[0032] Reference numerals:

[0033] 10. Voltage conversion unit; 20. Zero-crossing detection unit; 30. Micro-control unit; 40. Frequency conversion drive unit; 50. Current sampling unit; 11. AC step-down branch; 12. Rectification branch; 13. Filter branch; 14. First DC step-down branch; 15. Second DC step-down branch. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0035] In the description of the present invention, it should be understood that, with respect to descriptions of orientation, the orientations or positional relationships indicated by terms such as “center, longitudinal, transverse, length, width, thickness, up, down, front, back, left, right, vertical, horizontal, top, bottom, inside, outside, circumferential, radial, and axial” are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0037] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "set," "arranged," etc. should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0038] Reference below Figures 1 to 8 A driving circuit for a household appliance according to an embodiment of the first aspect of the present invention is described.

[0039] like Figure 1 As shown, the driving circuit according to the embodiment of the present invention includes a voltage conversion unit 10 , a zero-crossing detection unit 20 , a micro-control unit 30 , a variable frequency driving unit 40 and a current sampling unit 50 .

[0040] The input end of the voltage conversion unit 10 is connected to an AC power source to reduce the voltage of the AC power input from the AC power source and convert the reduced AC power into DC power with multiple voltage levels. The output end of the voltage conversion unit 10 includes an AC output end, a first DC output end, a second DC output end, and a third DC output end. The second DC output end is connected to the power supply end of the variable frequency drive unit 40 to power the frequency drive unit 40. The third DC output end is respectively connected to the power supply end of the zero-crossing detection unit 20, the power supply end of the micro-control unit 30, and the power supply end of the current sampling unit 50 to respectively power the zero-crossing detection unit 20, the micro-control unit 30, and the current sampling unit 50.

[0041] The input end of the zero-crossing detection unit 20 is connected to the AC output end of the voltage conversion unit 10 to detect the zero-crossing moment of the voltage at the AC output end of the voltage conversion unit 10; the output end Zero_check of the zero-crossing detection unit 20 is connected to the zero-crossing detection input pin of the micro-control unit 30 to send a zero-crossing detection signal to the micro-control unit 30 for processing.

[0042] The control signal input terminal Control of the variable frequency drive unit 40 is connected to the control signal output pin of the micro-control unit 30, the signal input terminal of the variable frequency drive unit 40 is connected to the live wire AC_L of the AC power supply, and the signal output terminal MOTOR_L of the variable frequency drive unit 40 is connected to the load. It should be noted that in the present application, the load is preferably an AC motor, which is conducive to reducing the cost of electronic control. One end of the connection terminal of the AC motor is connected to the signal output terminal MOTOR_L of the variable frequency drive unit 40, and the other end is connected to the neutral wire AC_N of the AC power supply; the working state of the AC motor is controlled by controlling the connection and disconnection of the live wire AC_L of the AC power supply and the signal output terminal MOTOR_L of the variable frequency drive unit 40, that is, the speed of the AC motor is controlled by controlling the working voltage of the AC motor.

[0043] The input terminal of the current sampling unit 50 is connected to the live wire AC_L of the AC power supply, and the output terminal Current_check of the current sampling unit 50 is connected to the current detection input pin of the micro-control unit 30 to detect the current magnitude during load operation. It should be noted that in the present application, the output terminal Current_check of the current sampling unit 50 outputs a voltage signal, and the micro-control unit 30 can convert the voltage signal into a corresponding current value.

[0044] The drive circuit in the present application controls the working state of the load by controlling the connection and disconnection of the live wire AC_L of the AC power supply and the signal output terminal MOTOR_L of the variable frequency drive unit 40, that is, the purpose of changing the load speed is achieved by changing the amplitude of the load working power supply. While achieving adjustable load speed, it can maintain the integrity of the AC power supply sine wave, thereby avoiding the generation of harmonics.

[0045] In some specific embodiments of the present invention, the micro-control unit 30 can be a single-chip microcomputer, which is a microcomputer that integrates major computer functional components such as a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), and input / output ports (I / O) on an integrated circuit chip.

[0046] like Figure 2 As shown, in some specific embodiments of the present invention, the voltage conversion unit 10 includes an AC step-down branch 11 , a rectifier branch 12 , a filter branch 13 , a first DC step-down branch 14 and a second DC step-down branch 15 .

[0047] Among them, the input end of the AC step-down branch 11 is connected to the AC power supply, and the output end of the AC step-down branch 11 is connected to the input end of the zero-crossing detection unit 20 as the AC output end; at the same time, the input end of the rectifier branch 12 is connected to the output end of the AC step-down branch 11 to rectify the AC power (24V) output by the AC step-down branch 11 into DC power (36V); the input end of the filter branch 13 is connected to the output end of the rectifier branch 12 to process the DC power (36V) output by the rectifier branch 12 into a DC output with a first voltage (24V); the output end of the filter branch 13 serves as the first DC output end, and the output voltage of the first DC output end is the first voltage (24V).

[0048] The input end of the first DC step-down branch 14 is connected to the output end of the filter branch 13 to process the DC power having the first voltage (24V) into a DC power output having the second voltage (12V); the output end of the first DC step-down branch 14 serves as the second DC output end, and the output voltage of the second DC output end is the second voltage (12V); the output end of the first DC step-down branch 14 is connected to the power supply end of the variable frequency drive unit 40 to supply power.

[0049] The input end of the second DC step-down branch 15 is connected to the output end of the first DC step-down branch 14 to convert the DC power having the second voltage (12V) into DC power having a third voltage (5V). The output end of the second DC step-down branch 15 serves as a third DC output end, and the output voltage of the third DC output end is the third voltage (5V). The output end of the second DC step-down branch 15 is connected to the power supply end of the zero-crossing detection unit 20, the power supply end of the micro-control unit 30, and the power supply end of the current sampling unit 50 to provide power.

[0050] like Figure 2 As shown, in some specific embodiments of the present invention, the AC step-down branch 11 includes a transformer T1; a first pin of the primary winding of the transformer T1 is connected to the live wire AC_L of the AC power supply, and a second pin of the primary winding of the transformer T1 is connected to the neutral wire AC_N of the AC power supply; a secondary winding of the transformer T1 is connected to the input end of the rectifier branch 12, and at the same time, the secondary winding of the transformer T1 is connected to the input end of the zero-crossing detection unit 20.

[0051] Specifically, the rectifier branch 12 includes a rectifier bridge, the first pin of the secondary winding of the transformer T1 is connected to the first end of the rectifier bridge, the second pin of the secondary winding of the transformer T1 is connected to the third end of the rectifier bridge, and the second end of the rectifier bridge is connected to the fourth end of the rectifier bridge through the filter branch 13.

[0052] like Figure 2As shown, in some specific embodiments of the present invention, the filter branch 13 includes a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a switching power supply U2; wherein the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are sequentially connected in parallel to the power supply terminal of the switching power supply U2; at the same time, the positive electrode of the power supply terminal of the switching power supply U2 is connected to the fourth terminal of the rectifier bridge, the negative electrode of the power supply terminal of the switching power supply U2 is connected to the second terminal of the rectifier bridge, and the second terminal of the rectifier bridge is grounded; the output terminal of the switching power supply U2 is connected to the first DC step-down branch 14, and the output terminal of the switching power supply U2 outputs the first voltage (24V) as the first DC output terminal. In this application, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 mainly play a filtering role.

[0053] like Figure 2 As shown, in some specific embodiments of the present invention, the first DC step-down branch 14 includes a first voltage stabilizing module U3; the positive electrode of the power supply terminal of the first voltage stabilizing module U3 is connected to the output terminal of the switching power supply U2, the negative electrode of the power supply terminal of the first voltage stabilizing module U3 is grounded, and the output terminal of the first voltage stabilizing module U3 is connected to the second DC step-down branch 15. The output terminal of the first voltage stabilizing module U3 serves as a second DC output terminal to output a second voltage (12V). The output terminal of the first voltage stabilizing module U3 is connected to the power supply terminal of the variable frequency drive unit 40 for power supply.

[0054] like Figure 2 As shown, in some specific embodiments of the present invention, the second DC step-down branch 15 includes a second voltage stabilizing module U4, a fifth capacitor C5 and a sixth capacitor C6; the positive pole of the power supply terminal of the second voltage stabilizing module U4 is connected to the output terminal of the first voltage stabilizing module U3, the negative pole of the power supply terminal of the second voltage stabilizing module U4 is grounded, the fifth capacitor C5 and the sixth capacitor C6 are sequentially connected in parallel between the output terminal and the negative pole of the power supply terminal of the second voltage stabilizing module U4, and the output terminal of the second voltage stabilizing module U4 outputs the third voltage (5V) as the third DC output terminal. In this application, the fifth capacitor C5 and the sixth capacitor C6 mainly play a filtering role. The output terminal of the second voltage stabilizing module U4 is respectively connected to the power supply terminal of the zero crossing detection unit 20, the power supply terminal of the micro-control unit 30 and the power supply terminal of the current sampling unit 50, so as to power the zero crossing detection unit 20, the micro-control unit 30 and the current sampling unit 50 respectively.

[0055] like Figure 2 As shown, in some specific embodiments of the present invention, the zero-crossing detection unit 20 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, an optocoupler U1, a fourth diode D4, a fifth diode D5, and a fifth transistor Q5. In the present application, the fifth transistor Q5 is an NPN transistor.

[0056] The anode of the fifth diode D5 is connected to the AC output end. Specifically, the anode of the fifth diode D5 is connected to the first pin of the secondary winding of the transformer T1, and the cathode of the fifth diode D5 is connected to the base of the fifth transistor Q5 through the third resistor R3; the emitter of the fifth transistor Q5 is connected to the anode of the fifth diode D5, and the collector of the fifth transistor Q5 is connected to the cathode of the input end of the optocoupler U1; the anode of the input end of the optocoupler U1 is connected in series to the cathode of the fifth diode D5 through the first resistor R1 and the second resistor R2; the anode of the fourth diode D4 is connected to the AC output end. Specifically, the anode of the fourth diode D4 is connected to the second pin of the secondary winding of the transformer T1, and the cathode of the fourth diode D4 is connected to the common node between the first resistor R1 and the second resistor R2; the emitter of the output end of the optocoupler U1 is grounded; the collector of the output end of the optocoupler U1 is connected to the third DC output end (third voltage 5V) through the fourth resistor R4, and the collector of the output end of the optocoupler U1 is connected to the zero-crossing detection input pin of the micro-control unit 30.

[0057] In this application, the fifth diode D5 is a voltage-stabilizing diode. By utilizing the reverse breakdown state of the PN junction, the voltage-stabilizing diode maintains the voltage across it essentially constant even when the power supply voltage fluctuates or other voltage fluctuations occur at various points in the circuit. The optocoupler U1 uses light as a medium for unidirectional transmission of electrical signals, electrically isolating the input and output signals.

[0058] Specifically, if Figure 3 As shown, the secondary winding of transformer T1 outputs 24V AC power. When the positive half cycle of the AC power is input from the second pin of the secondary winding of transformer T1, it passes through the fourth diode D4 and is stabilized to 4.7V by the action of the fifth diode D5, so that the fifth transistor Q5 is turned on, and then the optocoupler U1 is turned on, and the fourth pin of the optocoupler U1 outputs a low level. Since the negative half cycle of the AC power cannot pass through the fourth diode D4, the fifth transistor Q5 cannot be turned on, resulting in the optocoupler U1 being cut off and the fourth pin of the optocoupler U1 outputting a high level. The zero-crossing detection input pin of the micro-control unit 30 detects the transition moment of the high and low levels output by the fourth pin of the optocoupler U1, as shown in FIG. Figure 3 The B, C, D, and E moments are the zero-crossing moments of the alternating current.

[0059] like Figure 4 As shown, in some specific embodiments of the present invention, the variable frequency drive unit 40 includes a control branch 41 and a switch branch 42; the control signal input terminal Control of the control branch 41 is connected to the control signal output pin of the micro-control unit 30, and the output terminal of the control branch 41 is connected to the switch branch 42; the signal input terminal of the switch branch 42 is connected to the live wire AC_L of the AC power supply, and the signal output terminal of the switch branch 42 is connected to the load; the control branch 41 is used to control the on and off of the switch branch 42 according to the output signal of the control signal output pin of the micro-control unit 30.

[0060] Specifically, the control branch 41 includes a first diode D1, a twelfth resistor R12, and a control module 411. The anode of the first diode D1 is connected to the second DC output terminal (second voltage 12V), the cathode of the first diode D1 is connected to the first terminal of the control module 411, the control signal output pin of the micro-control unit 30 is connected to the second terminal of the control module 411 through the twelfth resistor R12, the third terminal of the control module 411 is grounded, and the first, fourth, and fifth terminals of the control module 411 are connected to the switch branch 42.

[0061] Furthermore, the control module 411 includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a thirteenth resistor R13, a fourteenth resistor R14, and a seventh diode D7. In the present application, the first transistor Q1 and the fourth transistor Q4 are NPN transistors, and the second transistor Q2 and the third transistor Q3 are PNP transistors.

[0062] Among them, the emitter of the third transistor Q3 is connected to the cathode of the first diode D1 as the first end of the control module 411; the emitter of the third transistor Q3 is connected to the base of the third transistor Q3 through the tenth resistor R10, the base of the third transistor Q3 is connected to the collector of the fourth transistor Q4 through the eleventh resistor R11, and the base of the fourth transistor Q4 is connected to one end of the twelfth resistor R12 as the second end of the control module 411; the base of the fourth transistor Q4 is grounded through the thirteenth resistor R13, and the emitter of the fourth transistor Q4 is grounded through the fourteenth resistor R14; the seventh diode The anode of D7 is grounded, and the anode of the seventh diode D7 serves as the third terminal of the control module 411; the cathode of the seventh diode D7 is connected to the collector of the second transistor Q2, and the collector of the second transistor Q2 serves as the fourth terminal of the control module 411; the collector of the second transistor Q2 is connected to the base of the second transistor Q2 through the ninth resistor R9, and the base of the second transistor Q2 is connected to the collector of the third transistor Q3 and the base of the first transistor Q1; the emitter of the second transistor Q2 is connected to the emitter of the first transistor Q1, and the collector of the first transistor Q1 serves as the fifth terminal of the control module 411.

[0063] like Figure 4As shown, in some specific embodiments of the present invention, the switch branch 42 includes a transistor M1, a first capacitor C1, a seventh capacitor C7, a seventh resistor R7 and an eighth resistor R8; the drain D of the transistor M1 is connected to the live wire AC_L of the AC power supply; the source S of the transistor M1 serves as the signal output terminal MOTOR_L of the variable frequency drive unit 40 and is connected to one end of the connection terminal of the load, and the other end of the connection terminal of the load is connected to the neutral wire AC_N of the AC power supply; the gate G of the transistor M1 is connected to the control branch 41 through the eighth resistor R8, specifically The gate G of the transistor M1 is connected to the emitter of the first transistor Q1 through the eighth resistor R8; the seventh resistor R7 and the seventh capacitor C7 are connected in parallel between the gate G and the source S of the transistor M1; one end of the first capacitor C1 is connected to the control branch 41, specifically, one end of the first capacitor C1 is connected to the collector of the first transistor Q1; the other end of the first capacitor C1 is connected to the control branch 41, specifically, the other end of the first capacitor C1 is connected to the collector of the second transistor Q2, and the other end of the first capacitor C1 is connected to the source S of the transistor M1.

[0064] It should be noted that in this application, transistor M1 is preferably an insulated gate bipolar transistor (IGBT), which has the advantages of low drive power and low saturation voltage. The seventh capacitor C7 is a bootstrap capacitor. The bootstrap capacitor utilizes the characteristic that the voltage across the capacitor cannot change suddenly. When a certain voltage is maintained across the capacitor, the voltage at the negative terminal of the capacitor is increased, while the voltage at the positive terminal remains at the original voltage difference at the negative terminal, which is equivalent to the voltage at the positive terminal being raised by the negative terminal.

[0065] In some specific embodiments of the present invention, when the control signal output pin of the micro-control unit 30 outputs a high level, that is, when the control signal input terminal Control of the variable frequency drive unit 40 inputs a high level, the current of the variable frequency drive unit 40 flows as follows: Figure 5 shown.

[0066] The base of the fourth transistor Q4 is at a high level, turning on the fourth transistor Q4. A voltage difference forms between the collector and base of the third transistor Q3, turning on the third transistor Q3. The base of the first transistor Q1 is at a high level, turning on the first transistor Q1. The base of the second transistor Q2 is at a high level, turning off the second transistor Q2. The voltage difference between the gate G of transistor M1 and the source S (MOTOR_L) is 12V (equal to the voltage across the seventh capacitor C7), turning on the transistor M1. At this time, the DC power (12V) continuously charges the seventh capacitor C7, while the seventh capacitor C7 continuously discharges along the current flow loop, maintaining the voltage difference between the gate G of transistor M1 and the source S (MOTOR_L) at 12V, ensuring that the transistor M1 remains on.

[0067] In some specific embodiments of the present invention, when the control signal output pin of the micro-control unit 30 outputs a low level, that is, when the control signal input terminal Control of the variable frequency drive unit 40 inputs a low level, the current of the variable frequency drive unit 40 flows as follows: Figure 6 shown.

[0068] The base of the fourth transistor Q4 is at a low level, turning off the fourth transistor Q4. There is no voltage difference between the collector and base of the third transistor Q3, turning off the third transistor Q3. The base of the first transistor Q1 is at a low level, turning off the first transistor Q1. The base of the second transistor Q2 is at a low level, turning on the second transistor Q2. The voltage difference between the gate G of transistor M1 and its source S (MOTOR_L) is 0V, turning off the transistor M1. At this point, the junction capacitance within transistor M1 begins to discharge along the current flow loop. When the junction capacitance within transistor M1 is fully discharged, M1 is completely turned off.

[0069] like Figure 7 As shown, in some specific embodiments of the present invention, the current sampling unit 50 includes a current transformer CT, an operational amplifier OP, a fifth resistor R5, a sixth resistor R6, a fifteenth resistor R15, a sixteenth resistor R16, and a seventeenth resistor R17; wherein the coil of the current transformer CT is sleeved on the live wire AC_L of the AC power supply; the first output pin of the current transformer CT is connected to the second output pin of the current transformer CT through the fifteenth resistor R15; the second output pin of the current transformer CT is connected to the negative phase input pin of the operational amplifier OP through the sixth resistor R6; the first output pin of the current transformer CT is connected to the negative phase input pin of the operational amplifier OP through the sixteenth resistor R6; Resistor R16 is connected to the non-inverting input pin of the operational amplifier OP; the negative input pin of the operational amplifier OP is connected to the output pin of the operational amplifier OP via a fifth resistor R5; the non-inverting input pin of the operational amplifier OP is grounded via a seventeenth resistor R17; the ground pin of the operational amplifier OP is grounded; the power pin of the operational amplifier OP is connected to the third DC output terminal (third voltage 5V); the output pin of the operational amplifier OP is connected to one end of the fifth resistor R5, and then serves as the output terminal Current_check of the current sampling unit 50, which is connected to the current detection input pin of the micro-control unit 30 to detect the current magnitude when the load is operating.

[0070] In the present application, the resistance of the fifteenth resistor R15 is preselected to be 100Ω, the resistance of the sixth resistor R6 and the sixteenth resistor R16 are preselected to be 10KΩ, and the resistance of the fifth resistor R5 and the seventeenth resistor R17 are preselected to be 22KΩ. The coil of the current transformer CT is mounted on the live wire AC_L of the AC power supply. When the current transformer CT senses the current on the live wire AC_L of the AC power supply, it outputs an induced current of 4 to 20 mA, generating a voltage difference of 0.4 to 2V across the fifteenth resistor R15. This voltage difference is amplified by the operational amplifier OP, and a voltage signal of 0.88 to 4.4V is output at the output terminal Current_check of the current sampling unit 50. After receiving this voltage signal, the current detection input pin of the micro-control unit 30 can convert it into the corresponding current value. The micro-control unit 30 adjusts the output voltage level of its control signal output pin according to the load current, thereby maintaining a stable load speed.

[0071] like Figure 8 As shown, in some specific embodiments of the present invention, the process of the micro-control unit adjusting the load speed according to the current size of the load during operation and the zero-crossing time of the AC power is as follows: the process includes a carrier generation process, a modulation wave output process, and a zero-crossing synchronization process:

[0072] Carrier generation process: The timer and counter are started inside the micro-control unit. The timing period of the timer is T, and the half period is T / 2. When the timing period starts, the counter starts from zero, and the count value of the counter is +1 every time a unit time t passes. When the timing reaches T / 2, the timer starts from the current count value, and the count value of the counter is -1 every time a unit time t passes. When the timing reaches T, both the timer and the counter are cleared.

[0073] Modulation wave output process: A sine wave target value is set within each T / 2 time. This target value can be determined based on the average value within each T / 2 time within one cycle of the target sine wave. During the T / 2 time of the carrier falling phase, when the counter count value reaches the target value, the micro-control unit controls the PWM output to a high level. During the T / 2 time of the carrier rising phase, when the counter count value reaches the target value, the micro-control unit controls the PWM output to a low level, thereby generating a sine wave voltage.

[0074] Zero-crossing synchronization process: combined Figure 3 As shown in the zero-crossing detection timing diagram, when the micro-control unit detects the zero-crossing moment of the AC power, the timer and counter are reset and restart the timing counting to achieve sinusoidal waveform synchronization and output a complete sinusoidal wave voltage for the load to work.

[0075] It should be noted that the target sine wave can be determined based on the target speed of the load. Higher speeds correspond to larger sine wave amplitudes, and vice versa. The microcontroller uses the calculated load current as feedback to maintain the target speed. Specifically, when the load current is low, a higher target sine wave value can be selected to modulate the load voltage. When the load current is high, a lower target sine wave value can be selected to modulate the load voltage.

[0076] A household appliance according to an embodiment of the second aspect of the present invention includes the driving circuit of the household appliance according to the embodiment of the first aspect of the present invention.

[0077] The household appliance of the embodiment of the present invention can realize long-term stable operation of the household appliance through the driving circuit of the above embodiment, which is beneficial to improving the reliability and competitiveness of the household appliance, reducing development costs, and increasing product applicability.

[0078] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0079] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the scope of the present invention.

Claims

1. A driving circuit for household appliances, characterized in that: It comprises a voltage conversion unit (10), a zero-crossing detection unit (20), a micro-control unit (30), a variable frequency drive unit (40) and a current sampling unit (50); The voltage conversion unit (10) is connected to an AC power source and is used to reduce the voltage of the AC power input by the AC power source and convert the reduced AC power into DC power with multiple voltage levels; the output end of the voltage conversion unit (10) includes an AC output end, a second DC output end, and a third DC output end; The zero-crossing detection unit (20) is used to detect the zero-crossing moment of the voltage at the AC output end; the input end of the zero-crossing detection unit (20) is connected to the AC output end, and the output end is connected to the micro-control unit (30); The current sampling unit (50) is used to detect the current when the load is working; the input end of the current sampling unit (50) is connected to the live wire of the AC power supply, and the output end is connected to the micro-control unit (30); The variable frequency drive unit (40) is used to adjust the rotation speed of the load according to the zero-crossing moment of the voltage at the AC output end and the current of the load when the load is working; the control signal input end of the variable frequency drive unit (40) is connected to the micro-control unit (30), the signal input end of the variable frequency drive unit (40) is connected to the live wire of the AC power supply, and the signal output end of the variable frequency drive unit (40) is connected to the load; The second DC output terminal is connected to the power supply terminal of the variable frequency drive unit (40) for power supply; the third DC output terminal is connected to the power supply terminals of the zero-crossing detection unit (20), the micro-control unit (30) and the current sampling unit (50) for power supply; The variable frequency drive unit (40) includes a control branch (41) and a switch branch (42); the control signal input end of the control branch (41) is connected to the micro-control unit (30), and the output end of the control branch (41) is connected to the switch branch (42); the signal input end of the switch branch (42) is connected to the live wire of the AC power supply, and the signal output end of the switch branch (42) is connected to the load; the control branch (41) controls the on / off of the switch branch (42) according to the output signal of the micro-control unit (30); The control branch (41) includes a first diode D1, a twelfth resistor R12, and a control module (411); the anode of the first diode D1 is connected to the second DC output terminal, the cathode of the first diode D1 is connected to the first terminal of the control module (411), the micro-control unit (30) is connected to the second terminal of the control module (411) via the twelfth resistor (R12), the third terminal of the control module (411) is grounded, and the first terminal, the fourth terminal, and the fifth terminal of the control module (411) are connected to the switch branch (42); The control module (411) includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a thirteenth resistor R13, a fourteenth resistor R14 and a seventh diode D7; the emitter of the third transistor Q3 is connected to the cathode of the first diode D1 as the first end of the control module (411); the emitter of the third transistor Q3 is connected to the base of the third transistor Q3 through the tenth resistor R10, the base of the third transistor Q3 is connected to the collector of the fourth transistor Q4 through the eleventh resistor R11, the base of the fourth transistor Q4 is connected to one end of the twelfth resistor R12 as the second end of the control module (411); the base of the fourth transistor Q4 is connected to the cathode of the first diode D1 through the tenth resistor R10. The thirteenth resistor R13 is grounded, and the emitter of the fourth transistor Q4 is grounded through the fourteenth resistor R14; the anode of the seventh diode D7 is grounded, and the anode of the seventh diode D7 serves as the third end of the control module (411); the cathode of the seventh diode D7 is connected to the collector of the second transistor Q2, and the collector of the second transistor Q2 serves as the fourth end of the control module (411); the collector of the second transistor Q2 is connected to the base of the second transistor Q2 through the ninth resistor R9, and the base of the second transistor Q2 is connected to the collector of the third transistor Q3 and the base of the first transistor Q1; the emitter of the second transistor Q2 is connected to the emitter of the first transistor Q1, and the collector of the first transistor Q1 serves as the fifth end of the control module (411); The zero-crossing detection unit (20) comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, an optocoupler U1, a fourth diode D4, a fifth diode D5 and a fifth transistor Q5; the anode of the fifth diode D5 is connected to the AC output end, the cathode of the fifth diode D5 is connected to the base of the fifth transistor Q5 through the third resistor R3; the emitter of the fifth transistor Q5 is connected to the anode of the fifth diode D5, and the collector of the fifth transistor Q5 is connected to the cathode of the input end of the optocoupler U1. The anode of the input end of the optocoupler U1 is connected in series to the cathode of the fifth diode D5 through the first resistor R1 and the second resistor R2; the anode of the fourth diode D4 is connected to the AC output end, and the cathode of the fourth diode D4 is connected to the common node between the first resistor R1 and the second resistor R2; the emitter of the output end of the optocoupler U1 is grounded; the collector of the output end of the optocoupler U1 is connected to the third DC output end through the fourth resistor R4, and the collector of the output end of the optocoupler U1 is connected to the micro-control unit (30).

2. The driving circuit of the household appliance according to claim 1, characterized in that: The voltage conversion unit (10) comprises an AC step-down branch (11), a rectifier branch (12), a filter branch (13), a first DC step-down branch (14) and a second DC step-down branch (15); the input end of the AC step-down branch (11) is connected to the AC power supply, and the output end of the AC step-down branch (11) serves as the AC output end; the input end of the rectifier branch (12) is connected to the output end of the AC step-down branch (11); the input end of the filter branch (13) is connected to the AC power supply; The output end of the rectifier branch (12) is connected, and the output end of the filter branch (13) serves as a first DC output end; the input end of the first DC step-down branch (14) is connected to the output end of the filter branch (13), and the output end of the first DC step-down branch (14) serves as a second DC output end; the input end of the second DC step-down branch (15) is connected to the output end of the first DC step-down branch (14), and the output end of the second DC step-down branch (15) serves as a third DC output end.

3. The driving circuit of the household appliance according to claim 2, characterized in that: The AC step-down branch (11) includes a transformer T1; a first pin of the primary winding of the transformer T1 is connected to the live wire of the AC power supply, and a second pin of the primary winding of the transformer T1 is connected to the neutral wire of the AC power supply; a secondary winding of the transformer T1 is connected to the input end of the rectifier branch (12) as the AC output end, and the secondary winding of the transformer T1 is connected to the input end of the zero-crossing detection unit (20).

4. The driving circuit of the household appliance according to claim 1, wherein: The switch branch (42) includes a transistor M1, a first capacitor C1, a seventh capacitor C7, a seventh resistor R7, and an eighth resistor R8; a drain D of the transistor M1 is connected to the live wire of the AC power supply; a source S of the transistor M1 is connected to one end of the connection terminal of the load as a signal output end of the variable frequency drive unit (40), and the other end of the connection terminal of the load is connected to the neutral wire of the AC power supply; a gate G of the transistor M1 is connected to the control branch (41) through the eighth resistor R8; the seventh resistor R7 and the seventh capacitor C7 are connected in parallel between the gate G and the source S of the transistor M1; one end of the first capacitor C1 is connected to the control branch (41), the other end of the first capacitor C1 is connected to the control branch (41), and the other end of the first capacitor C1 is connected to the source S of the transistor M1.

5. The driving circuit of the household appliance according to claim 1, characterized in that: The current sampling unit (50) comprises a current transformer CT, an operational amplifier OP, a fifth resistor R5, a sixth resistor R6, a fifteenth resistor R15, a sixteenth resistor R16 and a seventeenth resistor R17; the coil of the current transformer CT is sleeved on the live wire of the AC power supply; the first output pin of the current transformer CT is connected to the second output pin of the current transformer CT via the fifteenth resistor R15; the second output pin of the current transformer CT is connected to the negative phase input pin of the operational amplifier OP via the sixth resistor R6; the first output pin of the current transformer CT is connected to the negative phase input pin of the operational amplifier OP via the sixth resistor R6; The positive phase input pin of the operational amplifier OP is connected to the positive phase input pin of the operational amplifier OP through the sixteenth resistor R16; the negative phase input pin of the operational amplifier OP is connected to the output pin of the operational amplifier OP through the fifth resistor R5; the positive phase input pin of the operational amplifier OP is grounded through the seventeenth resistor R17; the ground pin of the operational amplifier OP is grounded; the power supply pin of the operational amplifier OP is connected to the third DC output terminal; the output pin of the operational amplifier OP is connected to one end of the fifth resistor R5 and then connected to the micro-control unit (30) as the output terminal of the current sampling unit (50).

6. A household appliance, characterized in that: The invention comprises the driving circuit of the household appliance according to any one of claims 1 to 5.

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