power detection circuit and control circuit

Abstract

A power detection circuit for detecting a current total input power of a resonant circuit. The power detection circuit comprises a detection circuit and an estimation circuit. The detection circuit receives a current signal and obtains a resonant tank fundamental power from the current signal to generate a fundamental power value. The current signal represents a resonant tank current generated by the resonant circuit. The estimation circuit receives the fundamental power value and estimates the current total input power from the fundamental power value to generate an estimated power value. The disclosure also relates to a control circuit.

Description

TECHNICAL FIELD

[0001] The present invention relates to a power detection circuit, and more particularly to a control circuit for controlling a resonant circuit by detecting a fundamental power of a resonant tank. BACKGROUND

[0002] A resonant circuit is a circuit used for energy conversion in an electronic system. For example, a resonant circuit is often used in a wireless signal transmitting and receiving device, a power converter, and the like. When a device uses a resonant circuit, the input power of a resonant tank in the resonant circuit determines the efficiency of using the device. Therefore, it is necessary to detect the input power of the resonant tank and to control or adjust the subsequent circuit or device or the device according to the input power. However, in the existing detection method of the input power of the resonant tank, the resonant tank current and voltage are usually obtained by high-speed sampling, multiplication, integration, and averaging, which increases the complexity of the operation and requires a high-order operation processor to perform the operation. SUMMARY

[0003] Therefore, the present invention proposes a power detection circuit and a control circuit, which estimate the input power of a resonant tank of a resonant circuit by a fundamental power of the resonant tank and control the resonant circuit according to the input power.

[0004] According to an embodiment of the present invention, a power detection circuit is provided for detecting a current total input power of a resonant circuit. The power detection circuit includes a detection circuit and an estimation circuit. The detection circuit receives a current signal and obtains a fundamental power of a resonant tank from the current signal to generate a fundamental power value. The current signal represents a resonant tank current generated by the resonant circuit. The estimation circuit receives the fundamental power value and estimates the current total input power from the fundamental power value to generate an estimated power value.

[0005] According to another embodiment of the present invention, a control circuit is provided for generating a first control signal to control a resonant circuit. The control circuit includes a detection circuit, an estimation circuit, and a regulation circuit. The detection circuit receives a current signal and obtains a fundamental power of a resonant tank from the current signal to generate a fundamental power value. The current signal represents a resonant tank current generated by the resonant circuit. The estimation circuit receives the fundamental power value and estimates a current total input power of the resonant circuit from the fundamental power value to generate an estimated power value. The regulation circuit receives the estimated power value and generates the first control signal. The regulation circuit calculates a power difference between the estimated power value and a preset power value and adjusts a duty cycle of the first control signal according to the power difference. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 An electronic device according to an embodiment of the present invention includes a resonant circuit and a power detection circuit.

[0007] Figure 2is indicative of Figure 1 the resonant tank voltage of the resonant circuit and its harmonic components in the resonant circuit.

[0008] Figure 3 represents an electronic device according to another embodiment of the present application, which comprises a resonant circuit, a power detection circuit, and a regulation circuit.

[0009] Figure 4 represents the percentage of the fundamental power, the second harmonic power, the third harmonic power, the coil loss power, and the stray loss power in the total power in the resonant tank under different operating periods of the resonant circuit.

[0010] Figure 5 represents the error of the parameter K L and K R and its corresponding parameter K1 under the general operation of the electromagnetic oven.

[0011] BRIEF DESCRIPTION OF DRAWINGS

[0012] 1, 3: electronic device

[0013] 10: resonant circuit

[0014] 11: power detection circuit

[0015] 12: driver

[0016] 13: current sensor

[0017] 14: regulation circuit

[0018] 15: control circuit

[0019] 100: voltage source

[0020] 110: detection circuit

[0021] 110A: band-pass filter

[0022] 110B: peak detector

[0023] 110C: measurement circuit

[0024] 111: estimation circuit

[0025] 140: subtractor

[0026] 141: power regulator

[0027] 142: signal generator

[0028] C r : resonant capacitor

[0029] G H ,G L : control signal

[0030] G OH ,G OL : switching signal

[0031] i r : resonant tank current

[0032] i r1 : fundamental frequency current

[0033] K1,K v : parameter

[0034] L eq : inductance

[0035] N10: common node

[0036] P r1 : fundamental frequency power

[0037] P r12 : current total input power

[0038] Q H : upper arm switching element

[0039] Q L : lower arm switching element

[0040] R eq : resistance

[0041] S11: indication signal

[0042] S14: adjustment signal

[0043] Si r : current signal

[0044] Si r1 : fundamental frequency current signal

[0045] V in : input voltage

[0046] V r : resonant tank voltage

[0047] VP d : power difference value

[0048] VP i : peak value

[0049] VP r : preset power value

[0050] VP r1 : fundamental frequency power value

[0051] VP r12 : estimated power value DETAILED DESCRIPTION

[0052] To make the above objects, features and advantages of the present application more clear and easily understood, a preferred embodiment is described below in detail with reference to the accompanying drawings.

[0053] Figure 1 is an electronic device according to an embodiment of the present application. Referring to Figure 1 , the electronic device 1 includes a resonant circuit 10, a power detection circuit 11, a driver 12, and a current sensor 13. The power detection circuit 11 is configured to detect a current total input power of the resonant circuit 10. In an embodiment, the electronic device 1 can be any device that needs to convert energy using a resonant circuit, such as a wireless signal transceiver, an electromagnetic oven, etc. In the following, the technical features of the present disclosure will be described with the electronic device 1 as an example of an electromagnetic oven.

[0054] Referring to Figure 1 , the resonant circuit 10 is coupled to a voltage source 100 to receive an input voltage V in . The resonant circuit 10 includes an upper arm switching element Q H , a lower arm switching element Q L , a resonant capacitor Cr, an inductor L eq , and a resistor R eq . The upper arm switching element Q H and the lower arm switching element Q L are connected in series between the positive terminal and the negative terminal of the voltage source 100. The driver 12 generates switching signals G OH and G OL to control the on / off states of the upper arm switching element Q H and the lower arm switching element Q L , respectively. In this embodiment, the switching signals G OH and G OL each have a duty cycle, so that the controlled upper arm switching element Q H and the lower arm switching element Q L operate according to their respective duty cycles. By controlling the switching signals G OH and G OL , the upper arm switching element Q H and the lower arm switching element Q L are switched between the on state and the off state, respectively, and the on time of the upper arm switching element Q H and the lower arm switching element Q L do not overlap.

[0055] Referring to Figure 1 , in the case where the electronic device 1 is an electromagnetic oven, the inductor L eq and the resistor R eqThese are the equivalent inductance and equivalent resistance of the cookware placed on the electronic device (induction cooker) 1. The series-connected resonant capacitor Cr and inductor L... eq and resistor R eq This forms the resonant slot of the resonant circuit 10, which is coupled to the upper arm switching element Q. H Switching element Q with lower arm L The common node N10 between them. The upper arm switching element Q is controlled. H Switching element Q with lower arm L Each switches between the on and off states, and the voltage v of a resonant tank... r Generated from the lower arm switching element Q L Between the drain and source, and a resonant tank current i r Flow through capacitor Cr. For example... Figure 1 As shown, the resonant tank current i r The flow originates from the common node N10 and flows to the resonant slot. The circuit architecture of the resonant circuit 10 reveals that it is a half-bridge series resonant circuit.

[0056] like Figure 1 As shown, the current sensor 13 is coupled to the resonant tank of the resonant circuit 10 at a common node N10 to sense the resonant tank current i. r The current sensor 13 detects the resonant tank current i. r Generate current signal Si r .exist Figure 1 In one embodiment, the current sensor 13 is disposed outside the power detection circuit 11. In other embodiments, the current sensor 13 may be included within the power detection circuit 11.

[0057] The power detection circuit 11 includes a detection circuit 110 and an estimation circuit 111. The detection circuit 110 receives the current signal Si. r And according to the current signal Si r Obtain the fundamental frequency power P of the resonant slot r1 To generate the fundamental frequency power value VP r1 The estimation circuit 111 then receives the baseband power value VP. r1 And according to the fundamental frequency power value VP r1 Estimate the current total input power P of the resonant tank. r12 To generate an estimated power value VP r12 The detailed operation of the detection circuit 110 and the estimation circuit 111 will be described below.

[0058] See Figure 1 The detection circuit 110 includes a bandpass filter 110A, a peak detector 110B, and a measurement circuit 110C. The bandpass filter 110A receives the current signal Si from the current sensor 13. rAnd for the current signal Si r Perform bandpass wave operation to obtain the fundamental frequency current i of the resonant slot. r1 (i.e., the resonant tank current i) r (The fundamental frequency component). The bandpass filter 110A generates a signal representing the fundamental frequency. r1 The fundamental frequency current signal Si r1 It is then output to the peak detection circuit 110B.

[0059] Peak detection circuit 110B is coupled to bandpass filter 110A and receives the fundamental frequency current signal Si from bandpass filter 110A. r1 Due to the fundamental frequency current signal Si r1 This represents the fundamental frequency current i. r1 Therefore, the peak detection circuit 110B can detect the fundamental frequency current signal Si. r1 To detect the fundamental frequency current i r1 peak value VP i The peak detection circuit 110B will detect the peak value VP. i Transmitted to measurement circuit 110C.

[0060] Measurement circuit 110C is coupled to peak detector 110B and receives peak value VP. i The measurement circuit 110C measures the peak value VP. i And the fundamental frequency power of the resonant slot is measured by the fundamental frequency resistor R1. To generate the corresponding fundamental frequency power value VP r1 Among them, in calculating the fundamental frequency power P r1 When, the parameter i in the above formula r1 (Fundamental frequency current) is determined by its peak value VP i Substitute it in. Calculate the fundamental frequency power P. r1 Then, the measurement circuit 110C generates the corresponding fundamental frequency power value VP. r1 The value of the baseband resistor R1 is then transmitted to the estimation circuit 111. In this embodiment, the value of the baseband resistor R1 is predetermined and can be stored in advance in the measurement circuit 110C. In other embodiments, the value of the baseband resistor R1 is predetermined and can be stored in advance in a memory (not shown) of the electronic device 1. When the power detection circuit 11 operates, the value of the baseband resistor R1 is read from the memory.

[0061] The estimation circuit 111 is coupled to the measurement circuit 110C and receives the fundamental frequency power value VP. r1 The estimation circuit 111 uses the baseband power value VP. r1 Obtain the fundamental frequency power P of the resonant slot r1 The estimation circuit 111 also receives an indication signal S11, which indicates the switching signal G. OHduty cycle of the switching signal G OH In this embodiment, the estimation circuit 111 determines, according to the indication signal S11, whether the duty cycle of the switching signal G OH is greater than a threshold value (e.g. 30% or 50%). In the case where the duty cycle of the switching signal G r1 is determined to be not greater than the threshold value, the estimation circuit 111 compensates the fundamental power P r12 according to a compensation parameter K to obtain an estimated current total input power P r12 , and generates an estimated power value VP r12 according to the estimated current total input power P OH . In the case where the duty cycle of the switching signal G r1 is determined to be greater than the threshold value, the estimation circuit 111 directly takes the fundamental power value VP r12 as the estimated power value VP r12 .

[0062] In this embodiment, the compensation parameter K is equal to the ratio of the preset double-frequency power to the preset fundamental power of the resonant tank at a specific duty cycle D. The compensation parameter K is predetermined and can be pre-stored in the estimation circuit 111. In other embodiments, the value of the compensation parameter is a predetermined parameter which can be pre-stored in a memory (not shown) of the electronic device 1. The compensation parameter K is read from the memory when the power detection circuit 11 is operated.

[0063] According to the embodiments of the present disclosure, the current total input power P r12 of the resonant tank can be estimated without complex calculation, since only the fundamental power of the resonant tank is needed. Moreover, the total input power P r12 (estimated power value VP r12 ) obtained by the present disclosure has high accuracy due to the compensation mechanism of the estimation circuit 111.

[0064] The analysis of how the power detection circuit 11 of the present disclosure can obtain the accurate current total input power P r12 from the fundamental power of the resonant tank will be described below.

[0065] Figure 2 represents the resonant tank voltage v r and its harmonic components. Referring to Figure 2 , the maximum value of the resonant tank voltage v r is the input voltage V in . v r1 represents the fundamental component of the resonant tank voltage v r (also referred to as the fundamental voltage of the resonant tank), and v r2 represents the double-frequency component of the resonant tank voltage v r (also referred to as the double-frequency voltage of the resonant tank).r3 the resonant tank voltage v r a three times frequency component (also referred to as a three times frequency voltage of the resonant tank) of the resonant tank voltage v r may be expressed as:

[0066]

[0067] wherein,

[0068] f s : represents a switching frequency of the resonant tank voltage v r ; and

[0069] represents a switching period of the switching frequency f s ; and

[0070] D: represents a duty cycle of the switching signal G OH , i.e., a ratio of a conduction time of the upper arm switching element Q H to a period time.

[0071] Equation (1) is expressed as:

[0072]

[0073] wherein,

[0074]

[0075] V in : represents a maximum value of a square wave of the resonant tank voltage v r ; and

[0076] n: represents a harmonic number of the resonant tank voltage v r ; and

[0077] θ n : an n-th harmonic phase angle.

[0078] Assuming that the duty cycle D is equal to 30%, D = 0.3 is brought into Equation (2) to obtain:

[0079]

[0080] In a case where only a peak value (maximum value) of the voltage is considered, the peak values of the fundamental frequency voltage v r1 , the second frequency voltage v r2 , and the third frequency voltage v r3 are 0.515 V in , 0.303 V in , and 0.066 V in , respectively. From these values, it can be observed that the fundamental frequency voltage v r1The peak value is greater than the second harmonic voltage V. r2 The peak value is much greater than the third harmonic voltage V. r3 The peak value. Therefore, the third harmonic voltage V can be ignored when detecting power. r3 The impact.

[0081] Since the input impedance of the resonant slot increases with the operating frequency of the resonant circuit 10, and according to the aforementioned fundamental frequency voltage v r1 Second harmonic voltage v r2 and the third harmonic voltage v r3 Therefore, based on the analysis, we only need to consider the influence of low-order voltage harmonics (i.e., fundamental frequency harmonics and second harmonic ramps) on the total input power of the resonant slot.

[0082] This disclosure describes the power distribution of the simulated resonant circuit 10. (See also...) Figure 4 The figure shows the fundamental frequency power P at duty cycles D of 10%, 20%, 30%, 40%, and 50%, respectively. r1 Second harmonic power P r2 Third harmonic power P r3 Coil power loss P coil Stray loss power P stray In total power P r The percentage it accounts for. For example... Figure 4 As shown, when the duty cycle D is equal to or less than 30%, the fundamental frequency power P r1 Percentage of total power P r Below 90%, third harmonic power P r3 Coil power loss P coil Stray loss power P stray Each accounts for a portion of the total power P r Less than 5%. When the duty cycle D is greater than 30%, the fundamental frequency power P r1 Almost equal to the total power P r The second harmonic power P r2 Third harmonic power P r3 Coil power loss P coil Stray loss power P stray Each also accounts for a portion of the total power P r Less than 5%.

[0083] Based on the above analysis, when the duty cycle D is large, due to the fundamental frequency power P r1 Almost equal to the total power P r Therefore, the estimation circuit 111 does not need to estimate the fundamental frequency power P. r1 Compensation is performed instead of directly converting the baseband power value VP. r1 As the estimated power value VP r12 That is, it can accurately estimate the current total input power P of the resonant circuit 10. r12As mentioned above, when the duty cycle D is small, the fundamental power P r1 accounts for less than 90% of the total power P r and the second harmonic power P r2 still accounts for a considerable proportion of the total power P r . In order to more accurately estimate the current total input power P r1 based on the fundamental power P r12 , the estimation circuit 111 compensates the fundamental power P r1 with a compensation parameter K to obtain an estimated power value VP r12 .

[0084] In one embodiment, the estimation circuit 111 sets a threshold value and determines whether to compensate the fundamental power P r1 based on whether the duty cycle D is greater than the threshold value. According to the above description, the threshold value can be set to 30%.

[0085] The definition of the compensation parameter K will be described below.

[0086] Suppose the current total input power P r12 is estimated based on the fundamental power P r1 and the second harmonic power P r2 of the resonant tank, P r12 can be expressed as:

[0087]

[0088] Substituting P and P into equation (4) and rearranging, we obtain:

[0089]

[0090] wherein,

[0091] the fundamental voltage of the resonant tank;

[0092] the second harmonic voltage of the resonant tank;

[0093] the input fundamental impedance of the resonant tank;

[0094] the input second harmonic impedance of the resonant tank;

[0095] R1, R2: the fundamental resistance and the second harmonic resistance of the resonant tank;

[0096] L1, L2: the fundamental inductance and the second harmonic inductance of the resonant tank;

[0097] ω s: operating angular velocity

[0098] Rewrite equation (5) as:

[0099] Rewrite equation (5) as:

[0100] = K, where = K v and = K1, equation (5) is rewritten as:

[0101] P r12 = P r1 (1 + K) = P r1 (1 + K v K1) equation (7)

[0102] Further,

[0103]

[0104] where ω o is the natural angular velocity of oscillation

[0105] According to equation (4) and equation (7), the compensation parameter K is the ratio of the second harmonic power P r2 to the fundamental power P r1 . According to equation (5), equation (7), and equation (8), the parameter K v is related to the ratio of the second harmonic voltage v r2 to the fundamental voltage v r1 , and the parameter K1 is related to the ratio of the second harmonic resistance to the fundamental resistance. When the duty cycle D is 10%, 20%, and 30%, the parameter K v is 0.9, 0.65, and 0.35, respectively. Therefore, according to equation (8), when the duty cycle D is larger, the proportion of the second harmonic power P r2 is smaller, which means that the error of estimating the current total input power P r1 from the fundamental power P r12 is smaller.

[0106] According to the above, when the duty cycle D is smaller, the parameter K v is larger, that is, the proportion of the second harmonic power P r2 is larger. Therefore, when estimating the current total input power P r1 from the fundamental power P r12 , the fundamental power P r1 needs to be compensated. In the embodiment of the present application, the fundamental power P r1 is compensated by the compensation parameter K, where the compensation parameter K is equal to the second harmonic power P​r2 the ratio of the fundamental power P r1 and equal to the parameter K v times the product of K v and K

[0107] According to equations (10) to (12), the parameter K L is determined according to the parameter K R and K Figure 5 is the error of the parameter K L and K R and its corresponding parameter K Figure 5 1 under the general operation of the electromagnetic oven. As shown in the figure, within a wide variation range of the parameter K L and K R (the region indicated by dots in the figure), the error of the parameter K Figure 5 1 is less than 10%, which means that the variation range of the parameter K R 1 is not large and is considered as a parameter not affected by the duty cycle D. Therefore, in the embodiment according to the present application, the electronic device 1 can first obtain the compensation parameter K v under a specific duty cycle D by testing or analysis, then obtain the parameter K v according to equation (8), and finally estimate the parameter K v 1 according to the compensation parameter K v and the parameter K v . The obtained compensation parameter K v and the parameter K v and K v 1 are stored in a memory of the electronic device 1 or in the estimation circuit 111 as predetermined parameters for use when the power detection circuit 11 operates.

[0108] In an embodiment, the electronic device 1 is predetermined with the compensation parameter K v and the parameter K r1 and K v 1 corresponding to the duty cycle D of 10%. In this case, the estimation circuit 111 sets the threshold value to 30% as the criterion for determining whether to compensate the fundamental power P r1 .

[0109] In other embodiments, the electronic device 1 can be predetermined with multiple compensation parameters K v and multiple parameters K OH and K v corresponding to multiple duty cycles as multiple predetermined parameters. When the power detection circuit 11 operates, a compensation parameter K OH or a set of parameters K v and K r1 1 among the multiple predetermined parameters can be selected according to the indication signal S OH 11 indicating the duty cycle D of the switching signal G OH to compensate the fundamental power P r1 .

[0110] In the above embodiments, the estimation circuit 11 determines whether to compensate the fundamental power P r1Compensation is performed. In other embodiments, regardless of the switching signal G OH What is the working cycle D? The estimation circuit 111 is based on the compensation parameter K for the fundamental frequency power P. r1 Compensation is performed to obtain an estimated current total input power P. r12 And based on the estimated current total input power P r12 Generate estimated power value VP r12 .

[0111] Figure 3 This refers to an electronic device according to another embodiment of the present invention. See also... Figure 3 Electronic device 3 includes Figure 1 The circuit includes a resonant circuit 10, a power detection circuit 11, a driver 12, and a current sensor 13. For the operation of the resonant circuit 10, power detection circuit 11, driver 12, and current sensor 13, please refer to [link to relevant documentation]. Figure 1 The description of the embodiments is omitted here.

[0112] like Figure 3 As shown, electronic device 3 also includes adjustment circuit 14. Power detection circuit 11 and adjustment circuit 14 together form control circuit 15 for controlling resonant circuit 10. Adjustment circuit 14 receives estimated power value VP from estimation circuit 111. r12 And generate control signal G H With G L The regulating circuit 14 calculates and estimates the power value VP. r12 With preset power value VP r The power difference between them, and the control signal G is adjusted according to this power difference. H With G L Each has its own work cycle.

[0113] exist Figure 3 In one embodiment, the current sensor 13 is disposed outside the control circuitry 15. In other embodiments, the current sensor 13 may be included within the control circuitry 15.

[0114] Driver 12 receives control signal G from regulating circuit 14 H and G L And according to the control signal G H With G L Each generates a switching signal G OH With G OL To control the upper arm switching element Q H Switching element Q with lower arm L The on / off state. Therefore, it can be seen that the regulating circuit 14 adjusts the control signal G. H With G L Each has its own working cycle, so the switching signal G can be adjusted or changed accordingly.OH With G OL Each has its own working cycle. In this embodiment, the control signal G H Working cycle and switching signal G OH The working cycles (D) are equal, and the control signal G L Working cycle and switching signal G OL The work cycles are equal.

[0115] See Figure 3 The adjustment circuit 14 includes a subtractor 140, a power regulator 141, and a signal generator 142. The subtractor 140 receives an estimated power value VP. r12 With preset power value VP r And calculate the estimated power value VP r12 With preset power value VP r The difference between them produces the power difference VP d Subtractor 140 will calculate the power difference VP. d Provided to power regulator 141.

[0116] Power regulator 141 receives power difference VP d And according to the power difference VP d At least one feature is used to generate the adjustment signal S14. In this embodiment, the power difference VP d At least one feature includes the power difference VP d The amplitude and polarity (positive or negative) of the signal must be at least one of these. The adjustment signal S14 is used to indicate how to adjust the control signal G. H With G L The working cycle, for example, the adjustment signal S14 indicates the adjustment control signal G. H With G L The adjustment range and direction (increase or decrease) of the working cycle are at least one of the following. The power regulator 141 provides the adjustment signal S14 to the signal generator 142.

[0117] Signal generator 142 receives adjustment signal S14 and generates control signal G H With G L Signal generator 142 adjusts control signal G according to adjustment signal S14. H With G L The working cycle. Signal generator 142 will control signal G. H With G L Provided to driver 12. Driver 12 then responds according to control signal G. H With G L Each generates a switching signal G OH With G OL To control the upper arm switching element QH The on / off state of the lower arm switching element Q L .

[0118] By the operation of the power detection circuit 11 and the regulating point circuit 14 in the control circuit 15, the control circuit 15 can estimate the current total input power P r1 of the resonant circuit 10 according to the fundamental power value VP r12 to generate an estimated power value VP r12 . Based on the difference between the estimated power value VP r12 and the desired preset power value VP r , the duty cycles of the control signals G H and G L are adjusted, thereby adjusting the switching signals G OH and G OL . Through the estimation and adjustment operation of the control circuit 15, the current total input power P r12 of the resonant circuit 10 is finally made close to or equal to the desired preset power value VP r .

[0119] Although the present application has been disclosed in its preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make changes and modifications without departing from the spirit and scope of the present application, and the scope of protection of the present application is defined by the claims.

Claims

1. A power detection circuit for detecting a current total input power of a resonant circuit, comprising: A detection circuit receives a current signal and obtains a fundamental frequency power of a resonant tank based on the current signal to generate a fundamental frequency power value, wherein the current signal represents a resonant tank current generated by the resonant circuit; and an estimation circuit receives the fundamental frequency power value and estimates the current total input power based on the fundamental frequency power value to generate an estimated power value, wherein... The resonant circuit includes a switching element, and the switching element operates according to a duty cycle; When the operating cycle is greater than a threshold value, the estimation circuit receives the baseband power value as the estimated power value; and When the operating cycle is not greater than the critical value, the estimation circuit obtains the fundamental frequency power of the resonant slot based on the fundamental frequency power value, and compensates the fundamental frequency power of the resonant slot according to a compensation parameter to generate the estimated power value.

2. The power detection circuit as described in claim 1, wherein, The compensation parameter relates to the ratio of a preset second harmonic power to a preset fundamental frequency power of the resonant circuit at a specific value during the operating cycle.

3. The power detection circuit as described in claim 1, wherein, The detection circuit includes: A bandpass filter receives the current signal and performs a bandpass wave operation on the current signal to generate a fundamental frequency current signal, wherein the fundamental frequency current signal represents the fundamental frequency current of a resonant slot of the resonant circuit. A peak detection circuit receives the fundamental frequency current signal and detects a peak value of the fundamental frequency current of the resonant tank based on the fundamental frequency current signal; and A measurement circuit receives the peak value and measures the fundamental frequency power of the resonant slot based on the peak value and a fundamental frequency resistor to generate the fundamental frequency power value.

4. The power detection circuit as described in claim 3, wherein, The fundamental frequency resistor represents the fundamental frequency resistor of a resonant slot in the resonant circuit.

5. A control circuit for generating a first control signal to control a resonant circuit, comprising: A detection circuit receives a current signal and obtains a fundamental frequency power of a resonant tank based on the current signal to generate a fundamental frequency power value, wherein the current signal represents a resonant tank current generated by the resonant circuit. An estimation circuit receives the fundamental frequency power value and estimates a current total input power of the resonant circuit based on the fundamental frequency power value to generate an estimated power value; and An adjustment circuit receives the estimated power value and generates the first control signal, calculates a power difference between the estimated power value and a preset power value, and adjusts a working cycle of the first control signal according to the power difference, wherein... When the operating period of the first control signal is greater than a threshold value, the estimation circuit receives the base frequency power value as the estimated power value; and When the working period of the first control signal is not greater than the critical value, the estimation circuit obtains the fundamental frequency power of the resonant slot based on the fundamental frequency power value, and compensates the fundamental frequency power of the resonant slot according to a compensation parameter to generate the estimated power value.

6. The control circuit as described in claim 5, wherein, The compensation parameter relates to the ratio of a preset second harmonic power to a preset fundamental frequency power of the resonant circuit at a specific value during the operating cycle.

7. The control circuit as described in claim 5, wherein, The detection circuit includes: A bandpass filter receives the current signal and performs a bandpass wave operation on the current signal to generate a fundamental frequency current signal, wherein the fundamental frequency current signal represents the fundamental frequency current of a resonant slot of the resonant circuit. A peak detection circuit receives the fundamental frequency current signal and detects a peak value of the fundamental frequency current of the resonant tank based on the fundamental frequency current signal; and A measurement circuit receives the peak value and a fundamental frequency resistor, and measures the fundamental frequency power of the resonant slot based on the peak value and the fundamental frequency resistor to generate the fundamental frequency power value.

8. The control circuit as described in claim 7, wherein, The fundamental frequency resistor represents the fundamental frequency resistor of a resonant slot in the resonant circuit.

9. The control circuit as described in claim 5, wherein, The regulating circuit includes: A subtractor receives the estimated power value and the preset power value, and calculates the difference between the estimated power value and the preset power value to generate the power difference; A power regulator receives the power difference and generates an adjustment signal based on at least one characteristic of the power difference; and A signal generator is used to generate the first control signal, wherein the signal generator receives the adjustment signal and adjusts the duty cycle of the first control signal according to the adjustment signal.

10. The control circuit as described in claim 9, wherein, The at least one feature of the power difference includes at least one of the amplitude of the power difference and a polarity.

11. The control circuit as described in claim 9, wherein, The adjustment signal indicates at least one of an adjustment range and an adjustment direction for adjusting the work cycle.

12. The control circuit as described in claim 5, wherein, The control circuit further generates a second control signal to control the resonant circuit, and the adjustment circuit also adjusts the second control signal according to the power difference.

13. The control circuit as described in claim 12, wherein, The resonant circuit includes an upper arm switching element and a lower arm switching element connected in series. The first control signal is used to control the upper arm switching element, and the second control signal is used to control the lower arm switching element.

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