TWI581550B - Method for Controlling a Converter - Google Patents

Description

Converter control method

The present invention relates to a control method, and more particularly to a converter control method.

Referring to FIG. 1 , a non-inverting buck-boost converter (NBB Converter) includes a first switch 911, a first diode 921, an inductor 93, and a second switch 912. A second diode 922, a capacitor 94, a gate driver 96, a pulse width modulation controller 97, and a compensation circuit 98. The non-inverting buck-boost converter is electrically connected to the DC power source 90 to receive an input voltage, convert the input voltage into an output voltage, and output the output voltage to a load 95. The compensation circuit 98 receives the output voltage and performs at least one of a phase margin (Phase Margin), a DC gain (DC Gain), and an increase in bandwidth to output a compensation voltage. The Pulse Width Modulation Controller (PWM Controller) 97 receives the compensation voltage and generates a control signal accordingly.

The non-inverting buck-boost converter operates between a buck mode, a boost mode, and a buck-boost mode. When the non-inverting buck-boost converter operates the buck-boost mode, the gate driver 96 outputs the control signal generated by the pulse width modulation controller 97 to the first switch 911 and the second switch 912 to At the same time, the duty ratio (Duty Cycle) of the first switch 911 and the second switch 912 is controlled.

When the non-inverting buck-boost converter is operated in the buck mode, the gate driver 96 controls the second switch 912 to be non-conducting, and outputs the control signal generated by the pulse width modulation controller 97 to the first A switch 911 controls the duty ratio d _a at which the first switch 911 is turned on. At this time, V _o =d _a *V _in .

When the non-inverting buck-boost converter operates the boost mode, the gate driver 96 controls the first switch 911 to be turned on, and outputs the control signal generated by the pulse width modulation controller 97 to the second switch. 912, to control the duty ratio d _{b of} the second switch 912 to be turned on. At this time, V _o =V _in /(1-d _b ).

Referring to FIG. 1 and FIG. 2, FIG. 2 illustrates the input voltage V _in , the compensation voltages V _c1 , V _c2 , the duty ratios d ₁ , d _{2 of} the control signals, a sawtooth upper limit voltage V _H , and a sawtooth wave The relationship between the lower limit voltages V _L . The pulse width modulation controller 97 includes a sawtooth wave signal, and compares the voltage magnitude according to the sawtooth wave signal and the compensation voltage V _c to generate the control signal and modulate the duty ratio d _{1 of} the control signal. , d ₂ (Figure 2). The maximum value and the minimum value of the sawtooth wave signal are the sawtooth wave upper limit voltage V _H and the sawtooth wave lower limit voltage V _{L , respectively} . When the non-inverting buck-boost converter operates in the buck mode and the boost mode, the compensation voltages are as shown in equations (1) and (2), respectively. Where V _M = V _H - V _L . ......(1) ......(2)

2 also illustrates that when the input voltage changes, for example, from V _in1 to V _in2 , the non-inverting buck-boost converter operates the buck mode or the boost mode, and the compensation voltage still satisfies the formula (1). Or formula (2), therefore, the compensation voltage difference ΔV _{c is} as shown in equations (3) and (4), respectively. ...(3) ...(4)

The conventional non-inverting step-up and step-down converter can operate between the buck mode, the boost mode, and the buck-boost mode, but actually implements high-efficiency voltage conversion when the input voltage is applied. When the output voltage is greater than or equal to the output voltage, the non-inverting buck-boost converter operates in the buck mode, and when the input voltage is less than the output voltage, the non-inverting buck-boost converter operates in the boost mode, that is, The non-inverting step-up and step-down converter will avoid operating in the buck-boost mode. However, the compensation circuit 98 of the conventional non-inverting buck-boost converter generally has a large compensation capacitor, and the compensation capacitor outputs the compensation voltage. Therefore, the compensation voltage cannot be changed immediately, and more importantly, It can be known from formula (3) or (4) that when the input voltage changes, the value of the compensation voltage difference ΔV _c is also large, and the non-inverting step-up and step-down converter takes time to make the output voltage stabilize again. In other words, the line voltage transient response of the non-inverting buck-boost converter is not good.

Accordingly, it is an object of the present invention to provide a converter control method that is fast in line voltage transient response.

Therefore, the converter control method of the present invention is applicable to a converter that receives a control signal to control whether a switch is turned on or off to convert an input voltage V _in into an output voltage V _o . The converter control method Implemented by a digital controller, the digital controller includes an analog-to-digital converter, a compensation circuit, and a hybrid controller. The converter control method includes the following steps: (a) analogy by the analog-to-digital converter The input voltage and the output voltage are respectively converted into digital input voltage and the output voltage; (b) calculating, by the hybrid controller, an auxiliary slope m _a according to the output voltage of the digit, and according to the input voltage of the digit And calculating a variable slope of the output voltage, wherein , α is a coefficient that is proportional to a difference between the input voltage and the output voltage; and (c) generated by the hybrid controller based at least on the auxiliary slope, the variable slope, and the compensation circuit the relationship between a compensation voltage V _c, calculation of the intersection of a voltage V _d, then calculate the coefficient α is obtained and the duty ratio control signal.

In some implementations, wherein the converter is a non-inverting buck-boost converter (NBB Converter) and operates in a buck mode, wherein in step (b), the The variable slope is m _saw , , β is a coefficient. In the step (c), the hybrid controller calculates the intersection voltage according to the following formula, and further calculates the coefficient α, the coefficient β, and the duty ratio d _{a of} the control signal, wherein V _valley is a parameter voltage, T _s is the period of the control signal, , .

In some implementations, wherein, in step (c), the duty cycle d _a of the control signal is . The coefficient α is equal to the coefficient β, and the coefficient α is . V _c,buck is a predetermined intermediate value, the predetermined intermediate value is equal to an average value of a predetermined maximum value and a predetermined minimum value, and the predetermined maximum value and the predetermined minimum value are respectively the input voltage and an output current of the converter The maximum and minimum values of the compensation voltage in the worst case (Worst Case) analysis.

In other implementations, when the converter is a non-inverting buck-boost converter (NBB Converter) and operates in a boost mode, wherein in step (b), the The slope is m _b , , β is a coefficient. In step (c), the hybrid controller is further based on another variable slope m _saw and formula Calculating the intersection voltage, and further calculating the coefficient α, the coefficient β, the coefficient γ, and the duty ratio d _{b of} the control signal, wherein V _valley is a parameter voltage, and T _s is a period of the control signal , , .

In other implementations, in step (c), the duty cycle d _b of the control signal is . The coefficient β is equal to the coefficient γ, and the coefficient α is . V _{c, boost} is a predetermined intermediate value, the predetermined intermediate value being equal to an average of a predetermined maximum value and a predetermined minimum value, wherein the predetermined maximum value and the predetermined minimum value are respectively the input voltage and an output current of the converter The maximum and minimum values of the compensation voltage in the worst case (Worst Case) analysis.

In other implementations, when the converter is a forward converter, a flyback converter, a half bridge converter, and a full bridge converter (Full Bridge) In any of the Converters, wherein in the step (c), the coefficient α is , V _{c, converter} is a predetermined intermediate value, the predetermined intermediate value is equal to an average value of a predetermined maximum value and a predetermined minimum value, the predetermined maximum value and the predetermined minimum value are respectively the input voltage and an output of the converter When the current is analyzed in the worst case (Worst Case), the maximum and minimum values of the compensation voltage, K is a coefficient and is related to the turns ratio of a transformer of the converter.

The effect of the present invention is that when the input voltage is changed, the hybrid controller calculates the duty ratio of the control signal of the converter according to the input voltage and the output voltage, so that the compensation voltage does not change or relative In the case that the amount of change in the technology is small, the control signal can control the converter to continuously output the stable output voltage, and realize a hybrid feedforward input (Hybrid Input Feedforward) with fast line voltage transient response (Line Transient) Response) converter control method.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 3, FIG. 3 is an embodiment of a non-inverting buck-boost converter (NBB Converter) to which the converter control method of the present invention is applied. The non-inverting buck-boost converter includes a first The switch Q _a , a first diode D ₁ , an inductor L, a second switch Q _b , a second diode D ₂ , a capacitor C _o , a gate driver (1) Scaling 71, 72, and a digital controller 8. The digital controller 8 includes an analog-to-digital converter (ADC) 6, a multiplexer (Mux) 5, a soft start circuit (Soft Start Circuit) 4, a compensation circuit (Compensator) 3, and a hybrid controller 2. .

The non-inverting step-up and step-down converter receives the input voltage V _{in in} constant current, converts the input voltage V _in into a continuous output voltage V _o , and outputs the output voltage V _o to a load R _L . The digital controller 8 can be implemented by a chip of a digital integrated circuit, and the two fixed ratio circuits 71, 72 respectively receive the input voltage V _in and the output voltage V _o , and the input voltage V _in and the output voltage V _o is scaled down to a voltage range that the wafer can withstand. The analog-to-digital converter 6 converts the analog signal of the input voltage V _in and the output voltage V _o into a digital signal. The multiplexer 5 outputs the input voltage V _in or the output voltage V _o to the soft start circuit 4 when the converter is initially started to prevent the output voltage V _{o from} drastically changing during the initial process. When the initial startup of the converter is completed, the multiplexer 5 outputs the input voltage V _in and the output voltage V _o to the compensation circuit 3. The compensation circuit 3 is equivalent to the compensation circuit 98 in the prior art for receiving the output voltage V _o and performing at least one of a phase margin (Phase Margin), a DC gain (DC Gain), and an increase in bandwidth of the loop. Compensation to output a compensation voltage. The hybrid controller 2 implements the converter control method and generates a control signal.

The non-inverting buck-boost converter operates between a Buck Mode, a Boost Mode, and a Buck-Boost Mode. When the non-inverting buck-boost converter operates the buck-boost mode, the gate driver 1 outputs the control signal generated by the hybrid controller 2 to the first switch Q _a and the second switch Q _b simultaneously controlling the first switch and the second switch Q _a Q _b oN duty ratio _{(Duty Cycle) d a, d} b.

When the non-inverting buck-boost converter is operated in the buck mode, the gate driver 1 controls the second switch Q _{b to be} non-conducting, and outputs the control signal generated by the hybrid controller 2 to the first switch Q _a , to control the duty ratio d _{a of} the first switch Q _{a to be} turned on. At this time, that is, Steady State, V _o =d _a *V _in .

When the non-inverting buck-boost converter operates the boost mode, the gate driver 1 controls the first switch Q _{a to be} turned on, and outputs the control signal generated by the hybrid controller 2 to the second switch Q _b To control the duty ratio d _{b of} the second switch Q _{b to be} turned on. At this time, that is, at steady state, V _o =V _in /(1-d _b ).

Referring to FIG. 3, FIG. 4 and FIG. 5, the converter control method includes steps S1 to S3. The steps of the converter control method when the non-inverting buck-boost converter operates in the buck mode will be described below. FIG 5 is a timing diagram indicating that the non-inverting buck-boost converter and the operating relationship between the input voltage V is changed _in a plurality of variables in the buck mode.

In step S1, the class than the analog digital converter to the input voltage V _in and the output voltage V _o respectively converted bit number of the input voltage V _in and the output voltage V _o.

In step S2, the hybrid controller 2 calculates an assist slope m _a The number of bits of the output voltage V _o, as shown in equation (5), and calculates a variable slope according to the number of bits of the input voltage V _in and the output voltage V _o m _sawa , as in formula (6). ...formula (5) Equation (6) where α is a coefficient, β is another coefficient, and the unit is one second (1/sec).

In step S3, the controller 2 based at least on the mixing of the secondary slope m _a, the relationship between the variable slope m _sawa, and said compensation circuit 3 generates the compensation voltage V _c, calculation of the intersection of a voltage V _da, further The coefficient α and the duty ratio d _{a of} the control signal are calculated. In more detail, the hybrid controller 2 calculates the intersection voltage _Vda according to the following formula, and further calculates the coefficient α, the coefficient β, and the duty ratio d _{a of} the control signal, wherein V _valley is a parameter voltage , T _s is the period of the control signal, that is, the sawtooth period corresponding to the prior art. ...formula (7) ...formula (8)

Equation (7) and formula (8) can be derived from Fig. 5, and then equations (5) to (7) are substituted into equation (8), and equation (9) can be obtained as follows. ...formula (9)

When the input voltage V _in is changed from V _in1 to V _in2 and reaches a steady state, the duty ratio d _{a of} the control signal should be the same as the duty ratio of the pulse width modulation control method of the prior art, and according to the inductance volt The Inductor Voltage-Second Balance theorem, the parameter voltage V _valley is equal to 0, and therefore, the conditional equation of the formula (10) can be obtained. ...formula (10)

In order for equation (10) to hold, the coefficient α must be equal to the coefficient β. Further, when the required load R _L of the load current changes, this time, the voltage V _valley parameter is not equal to 0, the equation (7) is the voltage V _valley parameter into the formula (9), can be obtained formula ( 11). ...formula (11)

When the load current required by the load R _L changes to a steady state, the duty ratio d _{a of} the control signal will be equal to V _o /V _in , and therefore, according to the inductance volt-second equilibrium theorem, the second of the formula (11) The item will be equal to 0. That is to say, when the load current changes, the output voltage V _o changes briefly. At this time, the compensation voltage V _c changes slightly to compensate for the change of the output voltage V _o . Therefore, in order to make the compensation voltage V _c The amount of change is minimized, and the coefficient α is set as in the formula (12), wherein V _{c, buck} is a predetermined intermediate value equal to an average of a predetermined maximum value and a predetermined minimum value, and the predetermined the predetermined maximum and minimum value, respectively, when the non-inverting buck-boost converter and the input voltage V _in an output current in a worst case analysis (worst case), the compensation of supply voltage V _c maximum and minimum values. ...formula (12)

Referring to FIG. 3, FIG. 4 and FIG. 6, the steps of the converter control method when the non-inverting step-up/down converter operates in the boost mode will be described below. Figure 6 is a timing diagram indicating that the non-inverting buck-boost converter and the operating relationship between the input voltage V is changed _in a plurality of variables in the boost mode.

Step S1 is the same as when operating in the buck mode, and in step S2, the auxiliary slope m _a and the variable slope m _{b are} redefined as in equations (14) and (15). ...formula (14) Equation (15) where α is a coefficient, β is another coefficient, and the unit is one second (1/sec).

In step S3, the operation is similar to the step-down mode, but the hybrid controller 2 calculates the intersection voltage V _db according to another variable slope m _sawb as in equation (13) and equations (16) and (17). And further calculating the coefficient α, the coefficient β, the coefficient γ, and the duty ratio d _{b of} the control signal, wherein V _valley is a parameter voltage, and T _s is a period of the control signal, that is, equivalent The sawtooth cycle of the prior art. ...formula (13) ...formula (16) ...formula (17)

Equation (16) to Equation (17) can be derived from Fig. 6, and equations (13) to (16) are substituted into equation (17), and equation (18) can be obtained as follows. ...formula (18)

Similar to when operating in the buck mode, when the input voltage V _in is changed from V _in1 to V _in2 and reaches a steady state, the duty ratio d _{b of} the control signal should be the pulse width modulation control method of the prior art. The duty ratio is the same, and according to the Inductor Voltage-Second Balance theorem, the parameter voltage V _valley is equal to 0, and therefore, the conditional equation of the formula (19) can be obtained. ...formula (19)

In order for equation (19) to hold, the coefficient β must be equal to the coefficient γ. Furthermore, when the load current required for the load R _L changes, at this time, the parameter voltage V _{valley is} not equal to 0, and the formula (18) can be rewritten into the formula (20). ...formula (20)

When the load current required by the load R _L changes to a steady state, the duty ratio d _{b of} the control signal will be equal to (V _o -V _in )/V _in , and therefore, according to the inductance volt-second equilibrium theorem, the formula The second item of 20) will be equal to zero. Similarly, when the load current changes, the output voltage V _o changes briefly. At this time, the compensation voltage V _c changes slightly to compensate for the change of the output voltage V _o . Therefore, in order to make the compensation voltage V _c The amount of change is minimized, and the coefficient α is set as in the formula (21), wherein V _{c, boost} is a predetermined intermediate value, the predetermined intermediate value being equal to an average value of a predetermined maximum value and a predetermined minimum value, the predetermined maximum value and said predetermined minimum value, respectively, of the converter when the input voltage V _in and an output current in a worst case analysis (worst case), the compensation of supply voltage V _c maximum and minimum values. ...formula (21)

From the equations (11) and (20), (V _c -αV _o T _s ) can be regarded as the adjustment amount of the compensation voltage V _c , that is, ΔV _c , which is compared with the conventional technique (3) and (4) It can be seen that the variation ΔV _c of the compensation voltage V _c generated by the converter control method of the present invention is much smaller than the compensation voltage difference ΔV _{c of the} prior art, and therefore, when the input voltage V _in changes, The present invention provides a fast line voltage transient response.

In addition, it should be particularly noted that in the embodiment, the converter is exemplified by a non-inverting buck-boost converter, and in other embodiments, when the converter is a forward converter (Forward Converter) ), any of the flyback converter (Flyback Converter), half bridge converter (Half Bridge Converter), and full bridge converter (Full Bridge Converter), due to the non-inverting buck-boost of the converter The main difference of the converter is the addition of a transformer such that the output voltage _Vo or the output current has a corresponding relationship with respect to the turns ratio of the coil. Similarly, the converter control method of the present invention is also applicable, and the formula for deriving the coefficient α is as follows, wherein V _{c, converter} is a predetermined intermediate value, the predetermined intermediate value being equal to a predetermined maximum value and a predetermined minimum value. The average value, the predetermined maximum value and the predetermined minimum value are respectively the maximum and minimum values of the input voltage V _in of the converter and an output current in a worst case (Worst Case) analysis, the compensation voltage V _c , K is a coefficient and is related to the coil turns ratio of the transformer of the converter. ...formula (22)

In addition, it should be particularly noted that when the hybrid controller 2 calculates the duty ratio of the control signal of the converter at different time points, the converter of the present invention is not required to be executed in each pulse period of the control signal. Steps S1 to S3 of the control method, for example, the hybrid controller 2 may first calculate the coefficients (α, β, γ) by performing a converter control method, and then the digits obtained with the step S1 at different time points The input voltage and the output voltage do not calculate the coefficients (α, β, γ) of step S3, but still calculate the duty cycle of the control signal. Furthermore, the formulas (11) and (20) for calculating the duty ratio of the control signal can also be substituted by other formulas mentioned in the specification or by other known formulas of the prior art in the field of the invention. Obtained with replacement, not limited to this.

In summary, the converter control method of the present invention can calculate the occupation of the control signal of the converter by the hybrid controller 2 according to the input voltage V _in and the output voltage V _o when the input voltage V _{in is} changed. The air ratio is such that the control signal can control the converter to continuously output the stable output voltage V _o while the compensation voltage V _c does not change or the amount of change of the prior art is small, thereby implementing a hybrid feedforward. The input (Hybrid Input Feedforward) and the fast line voltage transient response (Line Transient Response) can indeed achieve the object of the present invention.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the simple equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still Within the scope of the invention patent.

Q _a ‧‧‧first switch
Q _b ‧‧‧second switch
D ₁ ‧‧‧First Diode
D ₂ ‧‧‧Secondary
L‧‧‧Inductors
C _o ‧‧‧ capacitor
R _L ‧‧‧load
V _in ‧‧‧ input voltage
V _in1 ‧‧‧ input voltage
V _in2 ‧‧‧ input voltage
V _o ‧‧‧output voltage
V _H ‧‧‧Sawtooth upper limit voltage
V _L ‧‧‧Sawtooth lower limit voltage
V _c1 ‧‧‧compensation voltage
V _c2 ‧‧‧compensation voltage ΔV _c ‧‧‧compensation voltage difference
V _valley ‧‧‧parameter voltage
V _da1 ‧‧‧ intersection voltage
V _da2 ‧‧‧ intersection voltage
V _db1 ‧‧‧ intersection voltage
V _db2 ‧‧‧ intersection voltage
t‧‧‧Time
T _s ‧‧‧Sawtooth cycle
d ₁ , d ₂ ‧‧ ‧ duty cycle
d _a1 , d _a2 duty cycle
m _{sawa1 ‧‧‧Variable} slope
m _{sawa2 ‧‧‧Variable} slope
m _a ‧‧‧Auxiliary slope
m _b1 ‧‧‧Variable slope
m _b2 ‧‧‧Variable slope
m _sawb1 ·· variable slope
m _sawb2 ·· variable slope
1‧‧ ‧ brake driver
2‧‧‧Hybrid controller
3‧‧‧Compensation circuit
4‧‧‧Soft start circuit
5‧‧‧Multiplexer
6‧‧‧ analog digital converter
71, 72‧‧ ‧ fixed ratio circuit
8‧‧‧Digital Controller
90‧‧‧DC power supply
911‧‧‧ first switch
912‧‧‧second switch
921‧‧‧First Diode
922‧‧‧second diode
93‧‧‧Inductors
94‧‧‧ capacitor
95‧‧‧load
96‧‧ ‧ brake driver
97‧‧‧ Pulse width modulation controller
98‧‧‧Compensation circuit

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: Figure 1 is a circuit diagram illustrating a conventional non-inverting buck-boost converter; Figure 2 is a timing diagram FIG. 3 is a circuit diagram illustrating a non-inverting buck-boost converter applicable to the converter control method of the present invention; FIG. 4 is a flow chart. The steps of an embodiment of the converter control method of the present invention are illustrated; FIG. 5 is a timing diagram illustrating the operational relationship of the non-inverting buck-boost converter of the present invention operating in a buck mode; and FIG. 6 is a timing diagram. The operational relationship of the non-inverting step-up and step-down converter of the present invention operating in a boost mode will be described.

S1~S3‧‧‧ steps

Claims (6)

A converter control method is applicable to a converter that receives a control signal to control whether a switch is turned on or off to convert an input voltage V _in into an output voltage V _o . The converter control method is Implemented by a digital controller comprising an analog-to-digital converter, a compensation circuit, and a hybrid controller, the converter control method comprising the steps of: (a) analogizing the input by the analog-to-digital converter The voltage and the output voltage are respectively converted into digital input voltage and the output voltage; (b) calculating, by the hybrid controller, an auxiliary slope m _a according to the output voltage of the digit, and the output voltage according to the digit and the output The voltage is calculated as a variable slope, wherein , α is a coefficient that is proportional to a difference between the input voltage and the output voltage; and (c) generated by the hybrid controller based at least on the auxiliary slope, the variable slope, and the compensation circuit the relationship between a compensation voltage V _c, calculation of the intersection of a voltage V _d, then calculate the coefficient α is obtained and the duty ratio control signal. The converter control method according to claim 1, when the converter is a non-inverted buck-boost converter (NBB Converter) and operates in a buck mode, wherein in step (b) , defining the variable slope as m _saw , , β is a coefficient, in step (c), the hybrid controller calculates the intersection voltage according to the following formula, and further calculates the coefficient α, the coefficient β, and the duty ratio d _{a of} the control signal, wherein, V _Valley is a parameter voltage, T _s is the period of the control signal, , . The converter control method according to claim 2, wherein, in the step (c), the duty ratio d _a of the control signal is , the coefficient α is equal to the coefficient β, and the coefficient α is And Vc _{, buck} is a predetermined intermediate value, the predetermined intermediate value being equal to an average of a predetermined maximum value and a predetermined minimum value, wherein the predetermined maximum value and the predetermined minimum value are respectively the input voltage and an output of the converter The maximum and minimum values of the compensation voltage when the current is analyzed in the worst case (Worst Case). The converter control method according to claim 1, wherein when the converter is a non-inverting buck-boost converter (NBB Converter) and operating in a boost mode, wherein, in step (b) , defining the variable slope as m _b , , β is a coefficient, in step (c), the hybrid controller is further based on another variable slope m _saw and formula Calculating the intersection voltage, and further calculating the coefficient α, the coefficient β, the coefficient γ, and the duty ratio d _{b of} the control signal, wherein V _valley is a parameter voltage, and T _s is a period of the control signal , , . The converter control method according to claim 4, wherein, in the step (c), the duty ratio d _b of the control signal is , the coefficient β is equal to the coefficient γ, and the coefficient α is And V _{c, boost} is a predetermined intermediate value, the predetermined intermediate value being equal to an average of a predetermined maximum value and a predetermined minimum value, wherein the predetermined maximum value and the predetermined minimum value are respectively the input voltage and an output of the converter The maximum and minimum values of the compensation voltage when the current is analyzed in the worst case (Worst Case). The converter control method according to claim 1, wherein the converter is a forward converter, a flyback converter, a half bridge converter, and a full bridge conversion. In any of the (Full Bridge Converter), wherein in step (c), the coefficient α is And V _{c, the converter} is a predetermined intermediate value, the predetermined intermediate value being equal to an average value of a predetermined maximum value and a predetermined minimum value, wherein the predetermined maximum value and the predetermined minimum value are respectively the input voltage and an output of the converter When the current is analyzed in the worst case (Worst Case), the maximum and minimum values of the compensation voltage, K is a coefficient and is related to the turns ratio of a transformer of the converter.