TWI796918B - Power detection circuit and control circuit - Google Patents

Abstract

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 resonant slot baseband power according to the current signal to generate a baseband power value. The current signal represents a resonant slot current generated by the resonant circuit. The estimation circuit receives the baseband power value and estimates the current total input power according to the baseband power value to generate an estimated power value.

Description

Power detection circuit and control circuit

The present invention relates to a power detection circuit, in particular to a control circuit for controlling the resonant circuit by detecting the fundamental frequency power of the resonant tank.

A resonant circuit is a circuit used in electronic systems to convert energy. For example, resonant circuits are often used in wireless signal transmitting and receiving devices, power converters, and the like. When a device uses a resonant circuit, the input power of the resonant tank in the resonant circuit determines the performance 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 accordingly. However, in the existing detection method of the input power of the resonant tank, the current and voltage of the resonant tank are usually obtained by high-speed sampling, multiplication, integration and averaging, which increases the complexity of the calculation and requires a high-end computing processor. to execute.

In view of this, the present invention proposes a power detection circuit and a control circuit, which use the fundamental frequency power of the resonant tank to estimate the input power of the resonant tank of the resonant circuit, and control the resonant circuit accordingly.

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

According to another embodiment of the present invention, the present invention provides a control circuit for generating a first control signal to control a resonant circuit. The control circuit includes a detection circuit, an estimation circuit, and an adjustment circuit. The detection circuit receives the current signal, and obtains the fundamental frequency power of the resonant tank according to the current signal to generate the fundamental frequency power value. The current signal represents the resonant tank current generated by the resonant circuit. The estimation circuit receives the fundamental frequency power value, and estimates the current total input power of the resonant circuit according to the fundamental frequency power value to generate an estimated power value. The regulating circuit receives the estimated power value and generates a first control signal. The adjustment circuit calculates a power difference between the estimated power value and the preset power value, and adjusts the duty cycle of the first control signal according to the power difference.

In order to make the above-mentioned purpose, features and advantages of the present invention more comprehensible, a preferred embodiment will be exemplified below and described in detail in conjunction with the accompanying drawings.

FIG. 1 shows an electronic device according to an embodiment of the present invention. Referring to FIG. 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 used for detecting the current total input power of the resonant circuit 10 . In one embodiment, the electronic device 1 can be any device that needs to use a resonant circuit to convert energy, such as a wireless signal transceiver device, an electromagnetic oven, and the like. In the following, the technical features of the present application will be described by taking the electronic device 1 as an induction cooker as an example.

Referring to FIG. 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 _Req . 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 respectively control the on/off states of the upper arm switching element Q _H and the lower arm switching element Q _L . In this embodiment, each of the switching signals G _OH and G _OL has a duty cycle (Duty), so that the controlled upper arm switching element Q _H and the lower arm switching element Q _L operate according to their respective corresponding duty cycles. Through the control of the switching signals G _OH and G _OL , the upper arm switching element Q _H and the lower arm switching element Q _L are respectively switched between the on state and the off state, and the conduction time of the upper arm switching element Q _H and the lower arm switching element Q _{L is} Do not overlap.

Referring to FIG. 1 , when the electronic device 1 is an induction cooker, the inductance L _eq and the resistance R _eq in the resonant circuit 10 are respectively the equivalent inductance and equivalent resistance of the pan placed on the electronic device (induction cooker) 1 . The resonant capacitor Cr, inductor L _eq , and resistor R _eq connected in series form a resonant tank of the resonant circuit 10 , which is coupled to a common node N10 between the upper arm switching element Q _H and the lower arm switching element Q _L . By controlling the upper arm switching element Q _H and the lower arm switching element Q _L to switch between the on state and the off state respectively, a resonant tank voltage v _r is generated between the drain and the source of the lower arm switching element Q _L , and a The resonant tank current _ir flows through the capacitor Cr. As shown in Figure 1, the resonant tank current _ir flows from the common node N10 to the resonant tank. It can be known from the circuit structure of the resonant circuit 10 that the resonant circuit 10 is a half-bridge series resonant circuit.

As shown in FIG. 1 , 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 _ir . The current sensor 13 generates a current signal _{Si r according} to the sensed resonant tank current ir. In the embodiment shown in FIG. 1 , the current sensor 13 is configured outside the power detection circuit 11 . In other embodiments, the current sensor 13 can be included in the power detection circuit 11 .

The power detection circuit 11 includes a detection circuit 110 and an estimation circuit 111 . The detection circuit 110 receives the current signal _Sir , and obtains the fundamental frequency power P _r1 of the resonant tank according to the current signal _Sir to generate the fundamental frequency power value VP _r1 . The estimation circuit 111 receives the fundamental frequency power value VP _r1 , and estimates the current total input power P _r12 of the resonant tank according to the fundamental frequency power value VP _r1 to generate an estimated power value VP _r12 . The detailed operations of the detection circuit 110 and the estimation circuit 111 will be described below.

Referring to FIG. 1 , the detection circuit 110 includes a bandpass filter 110A, a peak detector 110B, and a measurement circuit 110C. The band-pass filter 110A receives the current signal _Sir from the current sensor 13, and performs a band-pass wave operation on the current signal _Sir to obtain the fundamental frequency current i _r1 of the resonant tank (that is, the fundamental frequency of the resonant tank current i _r Element). The bandpass filter 110A generates a fundamental-frequency current signal Si _r1 representing the fundamental-frequency voltage i _r1 , and outputs it to the peak detection circuit 110B.

The peak detection circuit 110B is coupled to the bandpass filter 110A and receives the fundamental frequency current signal Si _r1 from the bandpass filter 110A. Since the fundamental frequency current signal Si _r1 represents the fundamental frequency current i _r1 , the peak value detection circuit 110B can detect the peak value VP _i of the fundamental frequency current i _r1 through the fundamental frequency current signal Si _r1 . The peak value detection circuit 110B transmits the detected peak value VP _i to the measurement circuit 110C.

）以產生對應的基頻功率值VP _r1，其中，在計算基頻功率P _r1時，上述式子中的參數i _r1（基頻電流）是以其鋒值VP _i帶入。在計算出基頻功率P _r1後，量測電路110C產生對應的基頻功率值VP _r1，並將其傳送至估計電路111。在此實施例中，基頻電阻R ₁的值是預先決定的，其可預先儲存於量測電路110C。在其他實施例中，基頻電阻R ₁的值是預先決定的，其可預先儲存於電子裝置1的一記憶體（未顯示）中。當功率偵測電路11操作時，自該記憶體讀取基頻電阻R ₁的值。 The measurement circuit 110C is coupled to the peak detector 110B and receives the peak value VP _i . The measurement circuit _110C measures the fundamental frequency power _{P r1 (}

) to generate the corresponding fundamental frequency power value VP _r1 , wherein, when calculating the fundamental frequency power P _r1 , the parameter i _r1 (the fundamental frequency current) in the above formula is brought in by its peak value VP _i . After calculating the fundamental frequency power P _r1 , the measurement circuit 110C generates a corresponding fundamental frequency power value VP _r1 and transmits it to the estimation circuit 111 . In this embodiment, the value of the fundamental frequency resistor R ₁ is predetermined and can be stored in the measuring circuit 110C in advance. In other embodiments, the value of the fundamental frequency resistor R ₁ is predetermined, which can be stored in a memory (not shown) of the electronic device 1 in advance. When the power detection circuit 11 is operating, the value of the fundamental frequency resistor _R1 is read from the memory.

The estimation circuit 111 is coupled to the measurement circuit 110C and receives the fundamental frequency power value VP _r1 . The estimation circuit 111 obtains the fundamental frequency power P _r1 of the resonant tank through the fundamental frequency power value VP _r1 . The estimation circuit 111 also receives an indication signal S11, which indicates the duty cycle of the switching signal G _OH . In this embodiment, the estimation circuit 111 judges whether the duty cycle of the switching signal G _OH is greater than a threshold value (eg, 30% or 50%) according to the indication signal S11 . When it is determined that the duty cycle of the switching signal G _OH is not greater than the critical value, the estimation circuit 111 compensates the fundamental frequency power P _r1 according to the compensation parameter K to obtain the estimated current total input power P _r12 , and according to the estimated The current total input power P _r12 produces an estimated power value VP _r12 . When it is determined that the duty cycle of the switching signal G _OH is greater than the critical value, the estimation circuit 111 directly uses the fundamental frequency power value VP _r1 as the estimated power value VP _r12 .

In this embodiment, the compensation parameter K is equal to the ratio of the preset double frequency power to the preset fundamental frequency power of the resonant tank under a specific duty cycle D. The compensation parameter K is predetermined and can be stored in the estimation circuit 111 in advance. 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 . When the power detection circuit 11 is in operation, the compensation parameter K is read from the memory.

According to the embodiment of the present case, it can be seen that in this case, the current total input power P _r12 of the resonant tank can be estimated only by obtaining the fundamental frequency power of the resonant tank, without complicated calculations. In addition, due to the compensation mechanism of the estimation circuit 111 , the total input power P _r12 (estimated power value VP _r12 ) obtained in this case has higher accuracy.

The analysis that the power detection circuit 11 of the present application can obtain accurate current total input power P _r12 according to the fundamental frequency power of the resonant tank will be explained below.

式（1） 其中，

：表示諧振槽電壓v _r的切換頻率；

：表示切換頻率

的切換週期；以及

：表示切換信號G _OH的工作週期（也就是，上臂切換元件Q _H的導通時間佔週期時間的比例）。 FIG. 2 shows the resonant tank voltage v _r of the resonant circuit 10 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 frequency component of the resonant tank voltage v _r (also known as the fundamental frequency voltage of the resonant tank), v _r2 represents the double frequency component of the resonant tank voltage v _r (also known as the double frequency voltage of the resonant tank), v _r3 represents the triple frequency component of the resonant tank voltage v _r (also known as the triple frequency voltage of the resonant tank). The resonant tank voltage v _r can be expressed as:

Formula (1) where,

: Indicates the switching frequency of the resonant tank voltage v _r ;

: Indicates the switching frequency

The switching period of ; and

: Indicates the duty cycle of the switching signal G _OH (that is, the ratio of the conduction time of the upper arm switching element Q _H to the cycle time).

式（2） 其中，

；

：表示諧振槽電壓v _r的方波的最大值（即輸入電壓）；

：表示諧振槽電壓v _r的諧波次數；以及

：n次諧波相位角度。 Equation (1) is expressed through Fourier series expansion as:

Formula (2) where,

;

: Represents the maximum value of the square wave of the resonant tank voltage v _r (that is, the input voltage);

: represents the harmonic order of the resonant tank voltage v _r ; and

: nth harmonic phase angle.

=0.3帶入式（2）後得到：

式（3） Assuming that the duty cycle D is equal to 30% as an example, the

= 0.3 into formula (2) to get:

Formula (3)

、

及

。從這些數值可觀察到，基頻電壓v _r1的峰值大於二倍頻電壓v _r2的鋒值且更遠大於三倍頻電壓v _r3的峰值。因此，在偵測功率時可忽略三倍頻電壓v _r3的影響。 In the case of only considering the peak value (maximum value) of the voltage, the peak values of the fundamental frequency voltage v _r1 , the double frequency voltage v _r2 , and the triple frequency voltage v _r3 are respectively

,

and

. It can be observed from these values that the peak value of the fundamental frequency voltage v _r1 is greater than the peak value of the double frequency voltage v _r2 and far greater than the peak value of the triple frequency voltage v _r3 . Therefore, the influence of the triple frequency voltage v _r3 can be ignored when detecting power.

Since the input impedance of the resonant tank increases with the increase of the operating frequency of the resonant circuit 10, and according to the above analysis of the fundamental frequency voltage v _r1 , the double frequency voltage v _r2 , and the triple frequency voltage v _r3 , only the low order The influence of voltage harmonics (ie, fundamental frequency harmonics and double frequency ramps) on the total input power of the resonant tank.

The Applicant simulated the power distribution of the resonant circuit 10 . Refer to _{Figure 4, which shows the fundamental frequency power P r1 , double frequency power P r2 ,} triple frequency power P _r3 , The percentages of coil loss power P _coil and stray loss power P _stray in the total power P _r . As shown in Figure 4, when the duty cycle D is equal to or less than 30%, the fundamental frequency power P _r1 accounts for less than 90% of the total power P _r , the triple frequency power P _r3 , the coil loss power P _coil , and the stray loss power P _stray each accounts for less than 5% of the total power P _r . When the duty cycle D is greater than 30%, the fundamental frequency power P _r1 is almost equal to the total power P _r , while the double frequency power P _r2 , triple frequency power P _r3 , coil loss power P _coil , and stray loss power P _stray are also It accounts for less than 5% of the total power P _r .

According to the above analysis, when the duty cycle D is large, since the fundamental frequency power P _r1 is almost equal to the total power P _r , therefore, the estimation circuit 111 does not need to compensate the fundamental frequency power P _r1 , but directly calculates the fundamental frequency power value VP _r1 As the estimated power value VP _r12 , the current total input power P _r12 of the resonant circuit 10 can be accurately estimated. As mentioned above, when the duty cycle D is small, the fundamental frequency power P _r1 accounts for less than 90% of the total power P _r and the double frequency power P _r2 still occupies a considerable proportion of the total power P _r . In order to more accurately estimate the current total input power P _r12 according to the fundamental frequency power P _r1 , the estimation circuit 111 compensates the fundamental frequency power P _r1 with the compensation parameter K to obtain an estimated power value VP _r12 .

In one embodiment, the estimation circuit 111 sets a threshold value, and determines whether to compensate the fundamental frequency power P _r1 according to whether the duty cycle D is greater than the threshold value. According to the above description, this threshold value can be set at 30%.

The definition of the compensation parameter K will be explained below.

式（4） Assuming that the current total input power P _r12 is estimated by the fundamental frequency power P _r1 and the double frequency power P _r2 of the resonant tank, then P _r12 can be expressed as:

Formula (4)

以及

帶入式（4），並重新整理可得：

式（5） 其中，

：諧振槽的基頻電壓；

：諧振槽的二倍頻電壓；

：諧振槽的輸入基頻阻抗；

：諧振槽的輸入二倍頻阻抗；

：諧振槽的基頻電阻以及二倍頻電阻；

：諧振槽的基頻電感以及二倍頻電感；

：操作角速度。 Will

as well as

Bring into formula (4) and rearrange to get:

Formula (5) where,

: Fundamental frequency voltage of the resonant tank;

: double frequency voltage of the resonant tank;

: The input fundamental frequency impedance of the resonant tank;

: Input double-frequency impedance of the resonant tank;

: The fundamental frequency resistance and the double frequency resistance of the resonant tank;

: The fundamental frequency inductance and double frequency inductance of the resonant tank;

: Operating angular velocity.

改寫為：

式（6） In formula (5)

rewritten as:

Formula (6)

為K，其中，

為K _v且

為K ₁，那麼式（5）改寫為：

式（7） 此外，

式（8）

式（9）

式（10）

式（11）

式（12） 其中，

為自然協振角速度。 In order (5)

is K, where,

is K _v and

is K ₁ , then formula (5) is rewritten as:

Equation (7) In addition,

Formula (8)

Formula (9)

Formula (10)

Formula (11)

Formula (12) where,

is the natural resonance angular velocity.

According to formula (4) and formula (7), the compensation parameter K is the ratio of the double frequency power P _r2 to the fundamental frequency power P _r1 . According to formula (5), formula (7), and formula (8), the parameter K _v is related to the ratio of the double frequency voltage v _r2 to the fundamental frequency voltage v _r1 , and the parameter K ₁ is related to the double frequency resistance and The ratio of the fundamental frequency resistors. 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 formula (8), it can be seen that when the duty cycle D is larger, the proportion of the double frequency power P _r2 is lower, which means that when the current total input power P _r12 is estimated by the fundamental frequency power P _r1 The error is small.

According to the above, when the duty cycle D is smaller, the parameter K _v is larger, that is, the proportion of the double frequency power P _r2 is larger. Therefore, when estimating the current total input power P _r12 according to the fundamental frequency power P _r1 , it is necessary to compensate the fundamental frequency power P _r1 . In the embodiment of the present invention, the compensation parameter K is used to compensate the fundamental frequency power P _r1 , wherein the compensation parameter K is equal to the ratio of the double frequency power P _r2 to the fundamental frequency power P _r1 , and is equal to the parameters K _v and K ₁ The product of ( K=K _v K ₁ ).

According to the formulas (10)~(12), the parameter K ₁ is determined according to the parameters K _L and K _R. Figure 5 shows the errors of parameters K _L and K _R and their corresponding parameters K ₁ under the general operation of the induction cooker. As shown in Figure 5, within a wide variation range of parameters K _L and K _R (the area marked with dots in Figure 5), the error of parameter K ₁ is less than 10%, which means that the parameter K ₁ The range of change is not large, and it is regarded as a parameter that is not affected by the duty cycle D. Therefore, according to the embodiment of the present invention, the electronic device 1 of this case can first obtain the compensation parameter K under a specific duty cycle D by means of test or analysis, and then obtain the parameter K _v according to formula (8), and finally The parameter K ₁ is estimated according to the compensation parameter K and the parameter K _v . The obtained compensation parameter K and the parameters K _v and K ₁ are stored in a memory of the electronic device 1 or stored in the estimation circuit 111 as predetermined parameters for the operation of the power detection circuit 11 .

In one embodiment, the electronic device 1 predetermines the compensation parameter K corresponding to the duty cycle D being 10%, and the parameters K _v and K ₁ . In this case, the estimation circuit 111 sets the critical value as 30% as a criterion for determining whether to compensate the fundamental frequency power P _r1 .

In other embodiments, the electronic device 1 may predetermine a plurality of compensation parameters K and a plurality of parameters K _v and K ₁ corresponding to a plurality of duty cycles as the predetermined parameters. When the power detection circuit 11 is in operation, a compensation parameter K or a set of parameters K _v and K ₁ can be selected according to the indication signal S11 representing the duty cycle D of the switching signal G _OH to base frequency The power P _r1 is compensated.

In the above embodiment, the estimation circuit 11 determines whether to compensate the fundamental frequency power P _r1 according to whether the duty cycle D is greater than a threshold value. In other embodiments, regardless of the duty cycle D of the switching signal G _OH , the estimation circuit 111 compensates the fundamental frequency power P _r1 according to the compensation parameter K to obtain the estimated current total input power P _r12 , and according to the estimated current The total input power P _r12 produces an estimated power value VP _r12 .

FIG. 3 shows an electronic device according to another embodiment of the present invention. Referring to FIG. 3 , the electronic device 3 includes the resonant circuit 10 , the power detection circuit 11 , the driver 12 , and the current sensor 13 in FIG. 1 . For the operation of the resonant circuit 10 , the power detection circuit 11 , the driver 12 , and the current sensor 13 , please refer to the related description of the embodiment in FIG. 1 , and the description is omitted here.

As shown in FIG. 3 , the electronic device 3 further includes a regulating circuit 14 . The power detection circuit 11 and the regulation circuit 14 form a control circuit 15 for controlling the resonant circuit 10 . The regulating circuit 14 receives the estimated power value VP _r12 from the estimating circuit 111 and generates control signals _GH and _GL . The adjusting circuit 14 calculates a power difference between the estimated power value VP _r12 and the preset power value VP _r , and adjusts respective duty cycles of the control signals _GH and _GL according to the power difference.

In the embodiment of FIG. 3 , the current sensor 13 is configured outside the control circuit 15 . In other embodiments, the current sensor 13 can be included in the control circuit 15 .

The driver 12 receives the control signals GH and _GL from the regulating circuit 14, and generates switching signals G _OH and G _OL respectively according to the control signals GH and _GL to control _the switching of the upper arm switching element Q _H and the lower arm _switching element Q _L. on/off state. Therefore, it can be seen that the adjustment circuit 14 adjusts or changes the respective duty cycles of the switching signals G _OH and G _OL by adjusting the respective duty cycles _of the control signals GH and _GL . In this embodiment, the duty cycle of the control signal _GH is equal to the duty cycle (D) of the switching signal G _OH , and the duty cycle of the control signal _GL is equal to that of the switching signal G _OL .

Referring to FIG. 3 , the adjustment circuit 14 includes a subtractor 140 , a power regulator 141 , and a signal generator 142 . The subtractor 140 receives the estimated power value VP _r12 and the preset power value VP _r , and calculates a difference between the estimated power value VP _r12 and the preset power value VP _r to generate a power difference VP _d . The subtractor 140 provides the power difference VP _d to the power regulator 141 .

The power conditioner 141 receives the power difference VP _d , and generates an adjustment signal S14 according to at least one characteristic of the power difference VP _d . In this embodiment, at least one characteristic of the power difference VP _d includes at least one of the magnitude of the power difference VP _d and its polarity (positive or negative). The adjustment signal S14 is used to indicate how to adjust the duty cycle of the control signals G _H and _GL , for example, the adjustment signal S14 indicates the adjustment range and adjustment direction (increase or decrease) for adjusting the duty cycle of the control signals G _H and _GL ) at least one of. The power regulator 141 provides the regulation signal S14 to the signal generator 142 .

The signal generator 142 receives the adjustment signal S14 and generates control signals _GH and _GL . The signal generator 142 adjusts the duty cycles of the control signals _GH and _GL according to the adjustment signal S14. The signal generator 142 provides the control signals _GH and _GL to the driver 12 . The driver 12 generates switching signals G _OH and G _OL respectively according to the control signals G _H and _GL to control the on/off states of the upper arm switching element Q _H and the lower arm switching element Q _L .

Through the operation of the power detection circuit 11 and the adjustment point circuit 14 in the control circuit 15, the control circuit 15 can estimate the current total input power P _r12 of the resonant circuit 10 according to the fundamental frequency power value VP _r1 to generate an estimated power value VP _r12 . The duty cycles of the control signals _GH and _GL are adjusted based on the difference between the estimated power value VP _r12 and the desired preset power value VP _r , so as to adjust 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 to be close to or equal to the desired preset power value VP _r .

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in this art can make changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be subject to what is defined in the scope of the attached patent application.

1, 3: Electronic device 10: Resonant circuit 11: Power detection circuit 12: Driver 13: Current sensor 14: Adjustment circuit 15: Control circuit 100: Voltage source 110: Detection circuit 110A: Band-pass filter 110B: Peak detector 110C: measurement circuit 111: estimation circuit 140: subtractor 141: power regulator 142: signal generator C _r : resonant capacitor G _H , G _L : control signal G _OH , G _OL : switching signal i _r : Resonant tank current i _r1 : Fundamental frequency current K ₁ , K _v : Parameter L _eq : Inductance N10: Common node P _r1 : Fundamental frequency power P _r12 : Current total input power Q _H : Upper arm switching element Q _L : Lower arm Switching element R _eq : resistance S11 : indication signal S14 : adjustment signal Si _r : current signal Si _r1 : fundamental frequency current signal V _in : input voltage V _r : resonance tank voltage VP _d : power difference VP _i : peak value VP _r : Preset power value VP _r1 : Fundamental frequency power value VP _r12 : Estimated power value

FIG. 1 shows an electronic device according to an embodiment of the present invention, which includes a resonant circuit and a power detection circuit. Fig. 2 shows the resonant tank voltage of the resonant circuit in the resonant circuit of Fig. 1 and its harmonic components. FIG. 3 shows an electronic device according to another embodiment of the present invention, which includes a resonant circuit, a power detection circuit, and a regulating circuit. Figure 4 shows the percentages of the fundamental frequency power, double frequency power, triple frequency power, coil loss power, and stray loss power of the resonant tank in the total power under different duty cycles of the resonant circuit. Figure 5 shows the error of parameters K _L and K _R and their corresponding parameters K ₁ under the general operation of the induction cooker.

1: Electronic device

10: Resonant circuit

11: Power detection circuit

12: drive

13: Current sensor

100: voltage source

110: detection circuit

110A: Bandpass filter

110B: Peak detector

110C: Measuring circuit

111: Estimation circuit

C _r : Resonant capacitance

G _OH ,G _OL : switching signal

i _r : resonant tank current

i _r1 : Fundamental frequency current

K ₁ ,K _v : parameters

L _eq : inductance

N10: common node

P _r1 : Fundamental frequency power

P _r12 : current total input power

Q _H : upper arm switching element

Q _L : lower arm switching element

R _eq : resistance

S11: Indication signal

Si _r : current signal

Si _r1 : Fundamental frequency current signal

V _in : input voltage

V _r : Resonant tank voltage

VP _i : peak value

VP _r1 : Fundamental frequency power value

VP _r12 : estimated power value

Claims (17)

A power detection circuit for detecting a current total input power of a resonant circuit, comprising: a detection circuit receiving a current signal, and obtaining a fundamental frequency power of a resonance tank according to 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 according to the fundamental frequency power value to generate an estimated power value . The power detection circuit of claim 1, wherein: the resonance circuit includes a switching element, and the switching element operates according to a duty cycle; and the estimation circuit obtains the fundamental frequency power of the resonance tank according to the fundamental frequency power value, and according to A compensation parameter compensates the fundamental frequency power of the resonant tank to generate the estimated power value. Such as the power detection circuit of claim 1, wherein: the resonant circuit includes a switching element, and the switching element operates according to a duty cycle; when the duty cycle is greater than a critical value, the estimation circuit receives the fundamental frequency power value as as the estimated power value; and when the duty cycle is not greater than the critical value, the estimation circuit obtains the fundamental frequency power of the resonance tank according to the fundamental frequency power value and compensates the fundamental frequency power of the resonance tank according to a compensation parameter to generate The estimated power value. Such as the power detection circuit of claim 3, wherein the compensation parameter is It relates to the ratio of a preset double frequency power to a preset fundamental frequency power of the resonant circuit at a specific value of the duty cycle. The power detection circuit of claim 1, wherein the detection circuit includes: a band-pass filter for receiving the current signal, and performing a band-pass filtering operation on the current signal to generate a fundamental frequency current signal, wherein the fundamental frequency The current signal represents a fundamental frequency current of a resonant tank of the resonant circuit; a peak value detection circuit receives the fundamental frequency current signal, and detects a peak value of the fundamental frequency current of the resonant tank according to the fundamental frequency current signal; and a The measuring circuit receives the peak value, and measures the fundamental frequency power of the resonant tank according to the peak value and a fundamental frequency resistance to generate the fundamental frequency power value. The power detection circuit according to claim 5, wherein the fundamental frequency resistance represents a fundamental frequency resistance of a resonant tank of the resonant circuit. A control circuit for generating a first control signal to control a resonant circuit, comprising: a detection circuit receiving a current signal, and obtaining a fundamental frequency power of a resonance tank according to 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 according to the fundamental frequency power value to generate an estimated power value; and an adjustment circuit, receiving the estimated power value and generating the first control signal, calculating a power difference between the estimated power value and a preset power value, and according to the power difference The value adjusts a duty cycle of the first control signal. The control circuit according to claim 7, wherein: the estimation circuit obtains the fundamental frequency power of the resonance tank according to the fundamental frequency power value, and compensates the fundamental frequency power of the resonance tank according to a compensation parameter to generate the estimated power value. The control circuit according to claim 7, wherein: when the duty cycle of the first control signal is greater than a threshold value, the estimation circuit receives the fundamental frequency power value as the estimated power value; and when the duty cycle of the first control signal When the duty cycle is not greater than the critical value, the estimation circuit obtains the fundamental frequency power of the resonance tank according to the fundamental frequency power value and compensates the fundamental frequency power of the resonance tank according to a compensation parameter to generate the estimated power value. The control circuit according to claim 9, wherein the compensation parameter is related to a ratio of a preset double frequency power to a preset fundamental frequency power of the resonant circuit at a specific value of the duty cycle. The control circuit of claim 7, wherein the detection circuit includes: a band-pass filter for receiving the current signal, and performing a band-pass filter operation on the current signal to generate a fundamental frequency current signal, wherein the fundamental frequency current signal Representing a fundamental frequency current of a resonant tank of the resonant circuit; a peak value detection circuit, receiving the fundamental frequency current signal, and detecting a peak value of the fundamental frequency current of the resonant tank according to the fundamental frequency current signal; and a measurement The circuit receives the peak value and a fundamental frequency resistance, and measures the fundamental frequency power of the resonant tank according to the peak value and the fundamental frequency resistance to generate the fundamental frequency power value. Such as the control circuit of claim 11, wherein the fundamental frequency resistance represents A fundamental frequency resistance of the resonant tank of the resonant circuit. The control circuit according to claim 7, wherein the adjustment circuit includes: a subtractor, receiving the estimated power value and the preset power value, and calculating the difference between the estimated power value and the preset power value to generate the Power difference; a power regulator, receiving the power difference, and generating an adjustment signal according to at least one characteristic of the power difference; and a signal generator, used to generate the first control signal, wherein the signal generates The controller receives the adjustment signal, and adjusts the duty cycle of the first control signal according to the adjustment signal. The control circuit of claim 13, wherein the at least one characteristic of the power difference includes at least one of a magnitude and a polarity of the power difference. The control circuit according to claim 13, wherein the adjustment signal indicates at least one of an adjustment range and an adjustment direction for adjusting the duty cycle, for adjusting the duty cycle. The control circuit according to claim 7, wherein the control circuit further generates a second control signal to control the resonant circuit, and the adjustment circuit further adjusts the second control signal according to the power difference. The control circuit according to claim 16, 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 operated to control The lower arm side switches the element.

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