Resonant circuit control method and device, household appliance and air conditioner

Abstract

The application discloses a control method and device of a resonant circuit, a household appliance and an air conditioner. The control method comprises the following steps: detecting a resonant current of the resonant circuit; judging whether the resonant current satisfies a zero-voltage turn-on condition; if it is judged that the resonant current does not satisfy the zero-voltage turn-on condition, directly outputting a driving pulse, wherein the driving pulse is used for driving the switch tube to turn on; and if it is judged that the resonant current satisfies the zero-voltage turn-on condition, outputting the driving pulse after waiting for a set time. The control method can flexibly and reliably realize zero-voltage turn-on of the switch tube and control of a dead time of the switch tube.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to a control method, device, household appliance, and air conditioner for a resonant circuit. Background Technology

[0002] In a resonant circuit, zero-voltage turn-on of the switching transistor essentially means that the junction capacitance voltage of the transistor can discharge to zero within the dead time before the transistor is driven to turn on and current flows. During this turn-on instant, the current and voltage do not converge, achieving soft switching and reducing switching losses. However, if the dead time is too short, the transistor will not discharge completely. If the dead time is too long, the junction capacitance voltage will discharge to zero and then recharge. Therefore, both excessively large and excessively small dead times will affect the zero-voltage turn-on of the transistor.

[0003] Traditional dead-time control methods typically employ a fixed dead-time. However, under different load or output voltage conditions, the resonant current of the resonant circuit is not constant. Consequently, the time it takes for the voltage across the junction capacitor of the switching transistor to discharge to zero will vary. This can result in the fixed dead-time being too large or too small, failing to achieve zero-voltage turn-on and hindering system efficiency. Summary of the Invention

[0004] The present invention provides a control method, device, household appliance and air conditioner for a resonant circuit, which at least to some extent solves the technical problem that excessively large or small dead time affects the zero-voltage turn-on of the switching transistor and is not conducive to improving system efficiency.

[0005] In a first aspect, the present invention provides a control method for a resonant circuit, the resonant circuit including a switching transistor, the control method comprising:

[0006] Detect the resonant current of the resonant circuit;

[0007] Determine whether the resonant current meets the zero-voltage turn-on condition. If the resonant current does not meet the zero-voltage turn-on condition, output a drive pulse directly. The drive pulse is used to turn on the switch. If the resonant current meets the zero-voltage turn-on condition, output the drive pulse after waiting for a set time.

[0008] Optionally, determining whether the resonant current meets the zero-voltage turn-on condition includes:

[0009] Determine whether the resonant current is less than a current threshold. If the resonant current is less than the current threshold, determine that the resonant current does not meet the zero-voltage turn-on condition. If the resonant current is greater than or equal to the current threshold, determine that the resonant current meets the zero-voltage turn-on condition.

[0010] The current threshold is determined based on the junction capacitance of the switch transistor, the bus voltage value, and the time it takes for the resonant current to change from negative to positive.

[0011] Optionally, the set time is determined based on the junction capacitance of the switching transistor, the bus voltage value, and the detected resonant current.

[0012] Optionally, before detecting the resonant current of the resonant circuit, the control method further includes:

[0013] Detect the first voltage value across the switching transistor in the resonant circuit;

[0014] If the first voltage value is detected to be 0, the drive pulse is output.

[0015] Optionally, the control method further includes:

[0016] If it is determined that the resonant current meets the zero-voltage turn-on condition, after waiting for the set time, the second voltage value across the switch in the resonant circuit is re-detected.

[0017] If the second voltage value is detected to be 0, then the drive pulse is output;

[0018] If the second voltage value is detected to be non-zero, the resonant circuit is restarted.

[0019] In a second aspect, a control device for a resonant circuit is provided. The resonant circuit includes a switching transistor, and the control device includes a current detection circuit, a driving circuit, and a control module. The current detection circuit is connected to the control module, and the control module is connected to the driving circuit.

[0020] The current detection circuit is used to detect the resonant current of the resonant circuit.

[0021] The control module is used to acquire the resonant current detected by the current detection module and determine whether the resonant current meets the zero-voltage turn-on condition; if the resonant current does not meet the zero-voltage turn-on condition, the control module controls the drive circuit to directly output a drive pulse to drive the switch to turn on; if the resonant current meets the zero-voltage turn-on condition, the control module waits for a set time and then controls the drive circuit to output the drive pulse.

[0022] Optionally, the current detection circuit is a current detection differential amplifier circuit consisting of multiple detection resistors and a differential amplifier.

[0023] Optionally, the control device further includes a voltage detection circuit, which is connected to the control module;

[0024] The voltage detection circuit is used to detect the first voltage value across the switching transistor in the resonant circuit.

[0025] The control module is further configured to acquire the first voltage value detected by the voltage detection circuit, and when the voltage detection circuit detects that the first voltage value is low, control the driving circuit to directly output the driving pulse.

[0026] Optionally, the voltage detection circuit includes a first detection resistor, a second detection resistor, a first diode, and a second diode;

[0027] One end of the first detection resistor is connected to the resonant circuit, the other end of the first detection resistor is connected to one end of the second detection resistor, and the other end of the second detection resistor is grounded.

[0028] The anode of the first diode is connected to the junction of the first detection resistor and the second detection resistor, the cathode of the first diode is connected to the power supply voltage, the anode of the second diode is grounded, and the cathode of the second diode is connected to the anode of the first diode.

[0029] The connection point between the negative terminal of the second diode and the positive terminal of the first diode is the output terminal of the voltage detection circuit.

[0030] Optionally, the control module is further configured to:

[0031] If it is determined that the resonant current meets the zero-voltage turn-on condition, after waiting for the set time, the voltage detection circuit is controlled to re-detect the second voltage value across the switch in the resonant circuit.

[0032] If the second voltage value is detected to be 0, the driving circuit is controlled to output the driving pulse;

[0033] If the second voltage value is detected to be non-zero, the resonant circuit is restarted.

[0034] Optionally, the control module is further configured to:

[0035] Determine whether the resonant current is less than a current threshold. If the resonant current is less than the current threshold, determine that the resonant current does not meet the zero-voltage turn-on condition. If the resonant current is greater than or equal to the current threshold, determine that the resonant current meets the zero-voltage turn-on condition.

[0036] The current threshold is determined based on the junction capacitance of the switch transistor, the bus voltage value, and the time it takes for the resonant current to change from negative to positive.

[0037] Thirdly, a household appliance is provided, including the control device as described in the second aspect.

[0038] Fourthly, an air conditioner is provided, including the control device as described in the second aspect.

[0039] The one or more technical solutions provided in the embodiments of the present invention have at least the following effects or advantages:

[0040] This invention provides a control method, device, household appliance, and air conditioner for a resonant circuit. By detecting the resonant current of the resonant circuit and determining whether it meets the zero-voltage turn-on condition, the output time of the drive pulse is controlled, thereby automatically adjusting the turn-on time of the switching transistor and controlling its dead time. Therefore, this control method can flexibly and reliably achieve zero-voltage turn-on of the switching transistor, thus improving system efficiency. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart of a control method for a resonant circuit provided in an embodiment of the present invention;

[0043] Figure 2 This is a circuit diagram for detecting the current in a resonant circuit according to an embodiment of the present invention;

[0044] Figure 3 This is a waveform diagram of a switching transistor turning on normally with zero voltage, provided in an embodiment of the present invention.

[0045] Figure 4 This is a flowchart of another control method for a resonant circuit provided in an embodiment of the present invention;

[0046] Figure 5 This is a circuit diagram of a resonant circuit switching transistor for detecting voltage across the transistor, provided in an embodiment of the present invention.

[0047] Figure 6 This is a structural block diagram of a control device provided in an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] Figure 1 This is a flowchart of a control method for a resonant circuit provided in an embodiment of the present invention. This control method is applicable to resonant circuits at power transmitting terminals, such as... Figure 1 As shown, the control method includes:

[0050] Step S110: Detect the resonant current of the resonant circuit.

[0051] Specifically, the resonant current of the resonant circuit can be detected by setting up a current detection circuit.

[0052] Figure 2 This is a circuit diagram for detecting the current in a resonant circuit according to an embodiment of the present invention, such as... Figure 2 As shown, the resonant circuit includes multiple switching transistors, a resonant capacitor CT, a coil LT, and a resistor RS. The multiple switching transistors include a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, and a fourth switching transistor Q4.

[0053] In this circuit, the drains of the first switching transistor Q1 and the second switching transistor Q2 are both electrically connected to the voltage input terminal Vin. The source of the first switching transistor Q1 is connected to the drain of the third switching transistor Q3, and the source of the second switching transistor Q2 is connected to the drain of the fourth switching transistor Q4. The sources of the third switching transistor Q3 and the fourth switching transistor Q4 are both connected to one end of the resistor RS, and the other end of the resistor RS is grounded to GND. One end of the coil LT is connected to the source of the second switching transistor Q2 and the drain of the fourth switching transistor Q4, and the other end of the coil LT is connected to one end of the resonant capacitor CT. The other end of the resonant capacitor CT is connected to the source of the first switching transistor Q1 and the drain of the third switching transistor Q3.

[0054] The four switches Q1 to Q4 form a full-bridge inverter network, which can invert the DC power input to the voltage input terminal into AC power, and then transmit it through the coil LT. A dead time is set between the upper and lower switches on the same bridge arm. That is, when the first switch Q1 and the fourth switch Q4 are on, the second switch Q3 and the third switch Q4 are off. When the first switch Q1 and the fourth switch Q4 are off, the second switch Q3 and the third switch Q4 are on. This staggers the on and off times of the two switches on the same bridge arm, i.e., the dead time, to ensure that the upper and lower switches on the same bridge arm are always turned off first and then turned on.

[0055] In this embodiment, the four switching transistors Q1, Q2, Q3, and Q4 are all N-type metal-oxide-semiconductor field-effect transistors. Parasitic diodes are provided on each of the four switching transistors Q1, Q2, Q3, and Q4 to limit the current direction and prevent backflow. The anodes of the parasitic diodes on the four switching transistors Q1, Q2, Q3, and Q4 are connected to the source of each switching transistor, and the cathodes are connected to the drain of each switching transistor.

[0056] like Figure 2 As shown, the current detection circuit is a current detection differential amplifier circuit composed of multiple sensing resistors and a differential amplifier ICIA, that is, it uses an operational amplifier to detect the current. The multiple sensing resistors include the third sensing resistor R3, the fourth sensing resistor R4, the fifth sensing resistor R5, the sixth sensing resistor R6, and the seventh sensing resistor R7.

[0057] Specifically, one end of the fourth detection resistor R4 is connected to the source of the fourth switching transistor Q4, and the other end is connected to the non-inverting input of the differential amplifier ICIA. One end of the sixth detection resistor R6 is connected to the non-inverting input of the differential amplifier ICIA, and the other end is connected to the power supply VCC. One end of the fifth detection resistor R5 is grounded, and the other end is connected to the inverting input of the differential amplifier ICIA. One end of the third detection resistor R3 is connected to the inverting input of the differential amplifier ICIA, and the other end is connected to the output of the differential amplifier ICIA. One end of the seventh detection resistor R7 is connected to the output of the differential amplifier ICIA, and the other end is the resonant current output terminal. The seventh detection resistor R7 is a current conversion resistor; the voltage output from the differential amplifier ICIA is converted into current through the seventh detection resistor R7. By detecting the current at this output terminal, the resonant current of the resonant circuit can be detected.

[0058] Step S120: Determine whether the resonant current meets the zero-voltage turn-on condition.

[0059] Specifically, step S120 may include:

[0060] Determine whether the resonant current is less than the current threshold. If the resonant current is less than the current threshold, it is determined that the resonant current does not meet the zero-voltage turn-on condition. If the resonant current is greater than or equal to the current threshold, it is determined that the resonant current meets the zero-voltage turn-on condition.

[0061] In this embodiment, the current threshold is determined based on the junction capacitance of the switch transistor, the bus voltage, and the time it takes for the resonant current to change from negative to positive.

[0062] Specifically, the current threshold can be calculated using the following formula (1):

[0063] I0=CU / t (1)

[0064] In the above formula (1), Q represents the charge amount, C represents the junction capacitance of the switching transistor, and C is a fixed value that can be obtained from the switching transistor's datasheet. U represents the bus voltage value, that is, the voltage value input at the voltage input terminal Vin, and U is also a fixed value. I0 represents the current threshold, and t represents the time it takes for the current to change from negative to positive, which can be obtained by detecting the current change through a current detection circuit.

[0065] It should be noted that, in this embodiment, as Figure 2 The junction capacitances of the four switching transistors shown are all the same.

[0066] If the resonant current does not meet the zero-voltage turn-on condition, proceed directly to step S130. If the resonant current meets the zero-voltage turn-on condition, proceed to step S140.

[0067] Step S130: Output drive pulse.

[0068] Specifically, the gate of each switch can be connected to the driving circuit, and the driving circuit can output driving pulses to turn on each switch.

[0069] In this embodiment, the control module can control the timing of the drive pulses output by the drive circuit for each switch transistor, thereby controlling the dead time of the switch transistors. For example, drive pulses are simultaneously output to the first switch transistor Q1 and the fourth switch transistor Q4, driving the second switch transistor Q3 and the third switch transistor Q4 to conduct. Then, the output of drive pulses to the first switch transistor Q1 and the fourth switch transistor Q4 is stopped. After a dead time interval T, drive pulses are simultaneously output to the second switch transistor Q3 and the third switch transistor Q4, driving them to conduct.

[0070] Step S140: After waiting for the set time, output the drive pulse.

[0071] In this embodiment, the set time can be determined based on the junction capacitance of the switching transistor, the bus voltage value, and the detected resonant current.

[0072] Specifically, the set time t0 can be calculated using the following formula (2):

[0073] t0=CU / I (2)

[0074] In formula (2) above, C represents the junction capacitance of the switching transistor. C is a fixed value and can be obtained from the transistor's datasheet. U represents the bus voltage, i.e., the voltage input at the voltage input terminal Vin. U is also a fixed value. I represents the detected resonant current.

[0075] Figure 3This is a waveform diagram of a switching transistor turning on normally with zero voltage, provided in an embodiment of the present invention, such as... Figure 3 As shown in the figure, the solid line waveform represents the voltage V(MOS) across the switching transistor, and the dashed line waveform represents the drive pulse VGS4. Before the drive pulse is emitted, the voltage across the switching transistor drops to 0V, achieving zero-voltage turn-on and thus zero turn-on loss. This is because the resonant current is large enough under the action of the resonant circuit to discharge the junction capacitance in the switching transistor, causing the voltage across the switching transistor to become 0V. The drive pulse is emitted precisely when the resonant current changes from negative to positive (i.e.,...). Figure 3 At time t1, the switching transistor is turned on, thus achieving zero-voltage turn-on.

[0076] As mentioned above, for a switching transistor to achieve zero-voltage turn-on, the junction capacitance voltage of the transistor must be discharged to zero within the dead time before the transistor is driven to turn on and allow current to flow. At this point, the current and voltage do not converge during the turn-on instant, achieving soft switching. Therefore, to achieve zero-voltage turn-on, the resonant current must be large enough within the dead time to discharge the junction capacitance voltage of the transistor to zero.

[0077] In this embodiment, by setting a current threshold and determining whether the magnitude of the resonant current is greater than the current threshold, it can be determined whether the junction capacitor voltage of the switching transistor can discharge to zero within the dead time.

[0078] If it is determined in step S120 that the resonant current does not meet the zero-voltage turn-on condition, it means that the switching transistor of the resonant circuit cannot achieve zero-voltage turn-on at this time. In this case, step S130 can be executed directly to output a drive pulse. If it is determined that the resonant current meets the zero-voltage turn-on condition, then step S140 is executed, that is, after waiting for a set time, after the voltage across the switching transistor drops to 0V, a drive pulse is output to achieve zero-voltage turn-on of the switching transistor.

[0079] This invention also provides another control method for a resonant circuit, which is similar to... Figure 1 The difference in the control method shown is that this control method also needs to detect the voltage value across the switching transistor in the resonant circuit, and determine whether to output a drive pulse based on the detected voltage value and resonant current.

[0080] Figure 4 This is a flowchart of another control method for a resonant circuit provided in an embodiment of the present invention. This control method is applicable to the resonant circuit of a power transmitting end, such as... Figure 4 As shown, the control method includes:

[0081] Step S210: Detect the first voltage value across the switching transistor in the resonant circuit.

[0082] Specifically, a voltage detection circuit can be set up to detect the first voltage value across the switching transistor in the resonant circuit.

[0083] Figure 5 This is a circuit diagram provided by an embodiment of the present invention for detecting the voltage across the switching transistor in a resonant circuit, as shown below. Figure 5 As shown, the resonant circuit includes multiple switching transistors, a resonant capacitor CT, a coil LT, and a resistor RS. The multiple switching transistors include a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, and a fourth switching transistor Q4. The specific connection method of each component in the resonant circuit is as follows... Figure 2 Same as above, see details. Figure 2 The relevant descriptions will not be repeated here.

[0084] See Figure 5 The voltage detection circuit includes a first detection resistor R1, a second detection resistor R2, a first diode D1, and a second diode D2. One end of the first detection resistor R1 is connected to the source of the second switching transistor R2 and the drain of the fourth switching transistor R4. The other end of the first detection resistor R1 is connected to one end of the second detection resistor R2, and the other end of the second detection resistor R2 is grounded. The anode of the first diode D1 is connected to the junction of the first detection resistor R1 and the second detection resistor R2, and the cathode of the first diode D1 is connected to the power supply VCC. The anode of the second diode D2 is grounded, and the cathode of the second diode D2 is connected to the anode of the first diode D1.

[0085] The connection point between the negative terminal of the second diode D2 and the positive terminal of the first diode D1 is the output terminal of the voltage detection circuit. By detecting the voltage at this point, the first voltage value across the switching transistor in the resonant circuit can be obtained.

[0086] Step S220: Determine whether the first voltage value is 0.

[0087] If the first voltage value is detected to be high, then proceed to step S230. Otherwise, if the first voltage value is detected to be 0V, proceed directly to step S250.

[0088] Step S230: Detect the resonant current of the resonant circuit.

[0089] The specific implementation of step S230 is the same as that of step S110. For details, please refer to the relevant description of step S110 above.

[0090] Step S240: Determine whether the resonant current meets the zero-voltage turn-on condition.

[0091] The specific implementation of step S240 is the same as that of step S120, and you can refer to the relevant description of step S120 above.

[0092] Step S250: Output drive pulse.

[0093] The specific implementation of step S250 is the same as that of step S130, and you can refer to the relevant description of step S130 above.

[0094] Step S260: After waiting for the set time, re-detect the second voltage value across the switching transistor in the resonant circuit.

[0095] In this embodiment, the set time t0 can be determined based on the junction capacitance of the switching transistor, the bus voltage value, and the detected resonant current. For details, please refer to the relevant description of step S140 above; this embodiment will not repeat it here.

[0096] It should be noted that after waiting for the set time t0, the following can be used: Figure 5 The voltage detection circuit shown re-detects the second voltage value across the switching transistor in the resonant circuit.

[0097] Step S270: Determine whether the second voltage value is 0.

[0098] If the second voltage value is detected to be 0V, then step S250 is executed. Conversely, if the second voltage value is detected to be not 0V, then step S280 is executed.

[0099] Step S280: Initialize the control resonant circuit.

[0100] Theoretically, after a waiting time t, the voltage across the switching transistor in the resonant circuit should be 0V. If it is not 0V, it indicates that the resonant circuit is malfunctioning, and the control device needs to perform a restart operation to initialize the resonant circuit.

[0101] Based on the same invention, this embodiment of the invention also provides a control device for a resonant circuit, employing the above-described... Figure 1 or Figure 4 The control method described herein controls, for example, Figure 2 and Figure 5 The control device shown is suitable for the resonant circuit of an electrical power transmitter, which controls the switching of four transistors in the resonant circuit. Figure 6 This is a structural block diagram of a control device provided in an embodiment of the present invention, such as... Figure 6 As shown, the control device 600 includes a current detection circuit 610, a drive circuit 620, and a control module 630. The current detection circuit 610 is connected to the control module 630, and the control module 630 is connected to the drive circuit 620.

[0102] The current detection circuit 610 is used to detect the resonant current of the resonant circuit.

[0103] The control module 630 is used to acquire the resonant current detected by the current detection circuit 610 and determine whether the resonant current meets the zero-voltage turn-on condition. If the resonant current does not meet the zero-voltage turn-on condition, the control drive circuit 620 is directly outputting a drive pulse. If the resonant current meets the zero-voltage turn-on condition, the control drive circuit 620 is controlled to output a drive pulse after waiting for a set time.

[0104] In this embodiment, the specific structure of the current detection circuit 610 can be found in [reference needed]. Figure 2 The relevant descriptions will not be repeated here.

[0105] Optionally, the control module 630 is also used for:

[0106] Determine if the resonant current is less than the current threshold. If the resonant current is less than the current threshold, it is determined that the resonant current does not meet the zero-voltage turn-on condition. If the resonant current is greater than or equal to the current threshold, it is determined that the resonant current meets the zero-voltage turn-on condition.

[0107] The current threshold is determined based on the junction capacitance of the switching transistor, the bus voltage, and the time it takes for the resonant current to change from negative to positive.

[0108] Optionally, the control device 600 also includes a voltage detection circuit 640, which is connected to the control module 630.

[0109] The voltage detection circuit 640 is used to detect the first voltage value across the switching transistor in the resonant circuit. The control module 630 is also used to acquire the first voltage value detected by the voltage detection circuit 640, and when the voltage detection circuit 640 detects that the first voltage value is low, it controls the drive circuit 620 to directly output a drive pulse.

[0110] In this embodiment, the specific structure of the voltage detection circuit 640 can be found in [reference needed]. Figure 5 The relevant descriptions will not be repeated here.

[0111] Optionally, the control module 630 is also used for:

[0112] If the resonant current is determined to meet the zero-voltage turn-on condition, after waiting for a set time, the control voltage detection circuit 640 re-detects the second voltage value across the switching transistor in the resonant circuit.

[0113] If the second voltage value is detected to be 0, the control drive circuit 620 outputs a drive pulse;

[0114] If the second voltage value is detected to be non-zero, the resonant circuit is restarted.

[0115] Specifically, the control module 630 can be a central processing unit (CPU), which can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0116] The specific details of the above-mentioned control device can be understood by referring to the relevant descriptions and effects in the embodiments of the control method described above, and will not be repeated here.

[0117] This invention also provides a home appliance that includes the control device described in the above embodiments. Therefore, this home appliance also includes all the beneficial effects of the control device described in the above embodiments. To avoid repetition, it will not be described in detail here.

[0118] This invention also provides an air conditioner that includes the control device described in the above embodiments. Therefore, the air conditioner also includes all the beneficial effects of the control device described in the above embodiments, which will not be repeated here.

[0119] This invention provides a control method, device, household appliance, and air conditioner for a resonant circuit. By detecting the resonant current of the resonant circuit and determining whether it meets the zero-voltage turn-on condition, the output time of the drive pulse is controlled, thereby automatically adjusting the turn-on time of the switching transistor and controlling its dead time. Therefore, this control method can flexibly and reliably achieve zero-voltage turn-on of the switching transistor, thus improving system efficiency.

[0120] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0121] Similarly, it should be understood that, in order to simplify the invention and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of the invention should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim.

[0122] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the unit claims listing several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. Various modifications and variations of the invention will be apparent to those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of the claims of the invention.

Claims

1. A control method for a resonant circuit, the resonant circuit comprising a switching transistor, characterized in that, The control method includes: Detect the resonant current of the resonant circuit; It is determined whether the resonant current meets the zero-voltage turn-on condition. If the resonant current does not meet the zero-voltage turn-on condition, a drive pulse is directly output to drive the switch to turn on. If the resonant current meets the zero-voltage turn-on condition, the drive pulse is output after waiting for a set time. The determination of whether the resonant current meets the zero-voltage turn-on condition includes: Determine whether the resonant current is less than a current threshold. If the resonant current is less than the current threshold, determine that the resonant current does not meet the zero-voltage turn-on condition. If the resonant current is greater than or equal to the current threshold, determine that the resonant current meets the zero-voltage turn-on condition. The current threshold is determined based on the junction capacitance of the switch transistor, the bus voltage value, and the time it takes for the resonant current to change from negative to positive.

2. The control method as described in claim 1, characterized in that, The set time is determined based on the junction capacitance of the switching transistor, the bus voltage value, and the detected resonant current.

3. The control method as described in claim 1, characterized in that, Before detecting the resonant current of the resonant circuit, the control method further includes: Detect the first voltage value across the switching transistor in the resonant circuit; If the first voltage value is detected to be 0, the drive pulse is output.

4. The control method as described in claim 3, characterized in that, The control method further includes: If it is determined that the resonant current meets the zero-voltage turn-on condition, after waiting for the set time, the second voltage value across the switch in the resonant circuit is re-detected. If the second voltage value is detected to be 0, then the drive pulse is output; If the second voltage value is detected to be non-zero, the resonant circuit is restarted.

5. A control device for a resonant circuit, the resonant circuit comprising a switching transistor, characterized in that, The control device includes a current detection circuit, a drive circuit, and a control module. The current detection circuit is connected to the control module, and the control module is connected to the drive circuit. The current detection circuit is used to detect the resonant current of the resonant circuit. The control module is used to acquire the resonant current detected by the current detection circuit and determine whether the resonant current meets the zero-voltage turn-on condition. If it is determined that the resonant current does not meet the zero-voltage turn-on condition, then the drive circuit is controlled to directly output a drive pulse to drive the switch to turn on. If it is determined that the resonant current meets the zero-voltage turn-on condition, then after waiting for a set time, the drive circuit is controlled to output the drive pulse; The control module is used to determine whether the resonant current meets the zero-voltage turn-on condition: Determine whether the resonant current is less than a current threshold. If the resonant current is less than the current threshold, determine that the resonant current does not meet the zero-voltage turn-on condition. If the resonant current is greater than or equal to the current threshold, determine that the resonant current meets the zero-voltage turn-on condition. The current threshold is determined based on the junction capacitance of the switch transistor, the bus voltage value, and the time it takes for the resonant current to change from negative to positive.

6. The control device as described in claim 5, characterized in that, The current detection circuit is a current detection differential amplifier circuit consisting of multiple detection resistors and a differential amplifier.

7. The control device as described in claim 5, characterized in that, The control device further includes a voltage detection circuit, which is connected to the control module. The voltage detection circuit is used to detect the first voltage value across the switching transistor in the resonant circuit. The control module is further configured to acquire the first voltage value detected by the voltage detection circuit, and when the voltage detection circuit detects that the first voltage value is low, control the driving circuit to directly output the driving pulse.

8. The control device as described in claim 7, characterized in that, The voltage detection circuit includes a first detection resistor, a second detection resistor, a first diode, and a second diode; One end of the first detection resistor is connected to the resonant circuit, the other end of the first detection resistor is connected to one end of the second detection resistor, and the other end of the second detection resistor is grounded. The anode of the first diode is connected to the junction of the first detection resistor and the second detection resistor, the cathode of the first diode is connected to the power supply voltage, the anode of the second diode is grounded, and the cathode of the second diode is connected to the anode of the first diode. The connection point between the negative terminal of the second diode and the positive terminal of the first diode is the output terminal of the voltage detection circuit.

9. The control device as described in claim 7, characterized in that, The control module is also used for: If it is determined that the resonant current meets the zero-voltage turn-on condition, after waiting for the set time, the voltage detection circuit is controlled to re-detect the second voltage value across the switching transistor in the resonant circuit; If the second voltage value is detected to be 0, the driving circuit is controlled to output the driving pulse; If the second voltage value is detected to be non-zero, the resonant circuit is restarted.

10. A household appliance, characterized in that, Includes the control device as described in any one of claims 5 to 9.

11. An air conditioner, characterized in that, Includes the control device as described in any one of claims 5 to 9.

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