CN112054676B - A PID control method and system for a Boost DC-DC converter - Google Patents

Abstract

The invention relates to the technical field of Boost DC-DC converters, and specifically discloses a PID control method and system for the Boost DC-DC converter. The method comprises the steps of: S1. Using a state space average method to perform a PID control on the Boost DC-DC converter Modeling, obtain the duty cycle-output open-loop transfer function of the Boost DC-DC converter; S2. Determine the basic parameters of the Boost DC-DC converter, substitute the basic parameters into the duty cycle-output open-loop transfer function and draw the corresponding S3. Determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use PD to perform advance correction on the Boost DC-DC converter to make its phase margin and gain crossover frequency reach the set values; S4. Determine the steady-state rms value of the output voltage of the Boost DC-DC converter after PD correction; S5. According to the steady-state rms value of the output voltage, use PI to perform advance correction on the Boost DC-DC converter to make the output voltage steady-state rms value reach the set value. The invention enables the Boost DC-DC converter to output a constant voltage direct current with a required voltage value through a PID controller, and is efficient and accurate.

Description

A PID control method and system for a Boost DC-DC converter

technical field

The invention relates to the technical field of Boost DC-DC converters, in particular to a PID control method and system of the Boost DC-DC converter.

Background technique

A DC-DC converter converts a direct current into another direct current with fixed voltage or adjustable voltage, including direct direct current conversion circuit and indirect direct current conversion circuit. The direct direct current conversion circuit directly converts a direct current into Another type of direct current, and an indirect direct current converter circuit is a circuit that first converts direct current to alternating current and then converts alternating current to direct current. With the rapid development of DC-DC switching power supply technology, and because of its high efficiency, high power and high reliability, it is more and more widely used in industrial fields. The DC-DC switching power supply can realize the transformation from high-voltage power supply to low-voltage power supply, such as Buck DC-DC converter; it can also realize the transformation from low-voltage power supply to high-voltage power supply, such as DC-DC Boost converter.

How to achieve a constant output from low-voltage DC to high-voltage DC, there is still a lack of an efficient and precise control strategy.

SUMMARY OF THE INVENTION

The present invention provides a PID control method and system for a Boost DC-DC converter, and the technical problem to be solved is: how to efficiently and accurately realize constant output from low-voltage direct current to high-voltage direct current.

In order to solve the above technical problems, the present invention provides a PID control method of a Boost DC-DC converter, comprising the steps:

S1. Model the Boost DC-DC converter using the state space averaging method, and obtain the duty cycle-output open-loop transfer function of the Boost DC-DC converter;

S2. Determine the basic parameters of the Boost DC-DC converter, substitute the basic parameters into the duty cycle-output open-loop transfer function and draw the corresponding Bode diagram;

S3. Determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use the lead PD correction device to perform lead correction on the Boost DC-DC converter, so that its phase margin is greater than the set value and the gain crossover frequency reach the set value;

S4. Determine the steady-state effective value of the output voltage of the Boost DC-DC converter after PD correction;

S5. According to the steady-state effective value of the output voltage, use a hysteresis PI correction device to perform lag correction on the Boost DC-DC converter, so that the steady-state effective value of the output voltage reaches the set value.

Further, the Boost DC-DC converter includes a DC power supply, an inductor, a diode and a load, a MOS tube, and a capacitor;

The inductor, the diode and the load are sequentially connected between the positive and negative poles of the DC power supply, and the diode is connected in a forward direction;

The drain of the MOS tube is connected to the positive terminal of the diode, the source is connected to the negative terminal of the DC power supply E, and the gate is connected to the on-off time controller;

the capacitor is connected between the negative terminal of the diode and the negative terminal of the DC power supply;

The duty cycle-output open-loop transfer function is expressed as:

Among them, L, C, R ₀ represent the inductance, the capacitance, the inductance value, capacitance value, and resistance value of the load respectively, D represents the duty cycle, U ₀ represents the required output voltage, and s represents the The complex frequency of the Boost DC-DC converter.

In the step S3, the advance correction of the Boost DC-DC converter by using the advance PD correction device specifically includes the steps:

S31. Determine the phase correction amount according to the Bode diagram of the Boost DC-DC converter, and use a lead PD correction device without gain to perform phase lead correction on the Boost DC-DC converter, so that the phase margin is greater than the setting value;

S32. Analyze the phase-corrected Boost DC-DC converter, and use a correction device with gain k to perform gain correction on it, so that the gain crossover frequency reaches a set value.

Further, the step S31 is specifically:

To make the phase margin larger than its set value, let the phase increase of the leading PD correction device be θ, and the transfer function of the leading PD correction device without gain is:

while the division factor

The relationship between the gain crossover frequency f _g and the switching frequency f _s is:

Then, the gain crossover angular frequency ω _g =2πf _g ;

Let the maximum leading phase angle frequency of the leading PD correction device ω _m =ω _g , then the turning frequency of the leading PD correction transposition is obtained as:

于是得到

T为时间常数；

so get

T is the time constant;

中，得到不含增益的超前PD校正装置的传递函数。Substitute a and T into

, the transfer function of the lead PD correction device without gain is obtained.

Further, the step S32 is specifically:

A Bode diagram is drawn for the phase-corrected Boost DC-DC converter, and the amplitude L(ω _g ) of the gain crossover frequency point is determined, so after adding the gain k, there are: L(ω _g )+20lgk=0, Calculate the value of k.

Further, the step S5 is specifically:

Determine whether the steady-state effective value of the output voltage is less than its preset value, if not, do not correct, if so, use a hysteresis PI correction device to perform voltage correction, and the transfer function of the hysteresis PI correction device is:

As a rule of thumb, there is a corrected angular frequency ω≤0.1ω _g .

The invention also provides a PID control system of the Boost DC-DC converter, including the Boost DC-DC converter and a PID controller;

The PID controller is used to determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use the lead PD correction device to perform lead correction on the Boost DC-DC converter, so that the phase margin is greater than the set value. and the gain crossover frequency reaches the set value;

The PID controller is further configured to perform lag correction on the Boost DC-DC converter by using a lag PI correction device according to the steady-state effective value of the output voltage, so that the steady-state effective value of the output voltage reaches a set value;

The Boost DC-DC converter is used to convert the input initial DC voltage source into a boosted DC voltage source that reaches a preset voltage value under the control of the PID controller.

Preferably, the circuit structure of the Boost DC-DC converter is as described in the above-mentioned PID control system, and the duty cycle-output open-loop transfer function is expressed as:

Wherein, L, C, R ₀ represent the inductance, capacitance, and resistance of the inductor L, the capacitor C, and the load R ₀ respectively, U ₀ represents the required output voltage, and s represents the Boost DC - Complex frequency of the DC converter.

Specifically, the PID controller includes a leading PD correction device and a lag PI correction device;

The leading PD correction device is used to determine the phase correction amount according to the Bode diagram of the Boost DC-DC converter, and perform phase and gain lead correction on the Boost DC-DC converter, so that the phase margin is greater than the setting value and gain crossover frequency reach the set value;

The lag PI correction device is configured to perform voltage correction on the Boost DC-DC converter according to the steady-state effective value of the output voltage of the Boost DC-DC converter after correction by the leading PD correction device, so that the output voltage of the Boost DC-DC converter is stable The effective value reaches the set value.

Preferably, the leading PD correction device performs phase correction on the Boost DC-DC converter according to the process described in the above-mentioned PID control method;

The leading PD correction device performs gain correction on the Boost DC-DC converter according to the process described in the above-mentioned PID control method;

The hysteresis PI correction device performs voltage correction on the Boost DC-DC converter according to the process described in the above-mentioned PID control method.

The invention provides a PID control method and system for a Boost DC-DC converter. The PID controller performs closed-loop adjustment on the gain crossover frequency, phase margin, and steady-state effective value of the output voltage of the Boost DC-DC converter. Make the Boost DC-DC converter output a constant voltage DC with the required voltage value, and it is efficient and accurate.

Description of drawings

1 is a flow chart of steps of a PID control method for a Boost DC-DC converter provided in Embodiment 1 of the present invention;

2 is a circuit topology diagram of the Boost DC-DC converter provided in Embodiment 1 of the present invention;

3 is a circuit topology diagram of the Boost DC-DC converter shown in FIG. 2 when V is turned on and off according to Embodiment 1 of the present invention;

4 is a Bode diagram of the Boost DC-DC converter shown in FIG. 2 provided in Embodiment 1 of the present invention after basic parameters are determined;

FIG. 5 is a Bode diagram of the Boost DC-DC converter shown in FIG. 2 provided in Embodiment 1 of the present invention after adding a calibration device without gain;

6 is a Bode diagram of the Boost DC-DC converter shown in FIG. 2 provided in Embodiment 1 of the present invention after adding a correction device containing gain;

7 is a simulation model diagram of the Boost DC-DC converter shown in FIG. 2 provided in Embodiment 1 of the present invention;

FIG. 8 is a dynamic curve diagram of state variables of the simulation model shown in FIG. 7 provided by Embodiment 1 of the present invention;

Fig. 9 is a simulation model diagram of adding a calibration device containing gain in the Boost DC-DC converter shown in Fig. 2 provided by Embodiment 1 of the present invention;

10 is a simulation model diagram of adding a PID controller to the Boost DC-DC converter shown in FIG. 2 provided in Embodiment 1 of the present invention;

FIG. 11 is an output voltage waveform diagram when the simulation model shown in FIG. 10 is simulated according to Embodiment 1 of the present invention;

FIG. 12 is a closed-loop control schematic diagram of a PID control method for a Boost DC-DC converter provided in Embodiment 1 of the present invention.

Detailed ways

The embodiments of the present invention will be explained in detail below in conjunction with the accompanying drawings. The examples are given only for the purpose of illustration and should not be construed as a limitation of the present invention. The accompanying drawings are only used for reference and description, and do not constitute a limitation on the protection scope of the patent of the present invention. limitation, since many changes may be made in the present invention without departing from the spirit and scope of the invention.

Example 1

A PID control method for a Boost DC-DC converter provided by an embodiment of the present invention, as shown in FIG. 1 , includes the steps:

S1. Model the Boost DC-DC converter using the state space averaging method, and obtain the duty cycle-output open-loop transfer function of the Boost DC-DC converter;

S2. Determine the basic parameters of the Boost DC-DC converter, substitute the basic parameters into the duty cycle-output open-loop transfer function and draw the corresponding Bode diagram;

S3. Determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use the lead PD correction device to perform lead correction on the Boost DC-DC converter, so that the phase margin is greater than the set value and the gain crossover frequency reaches the set value;

S4. Determine the steady-state effective value of the output voltage of the Boost DC-DC converter after PD correction;

S5. According to the steady-state effective value of the output voltage, use the lag PI correction device to perform lag correction on the Boost DC-DC converter, so that the steady-state effective value of the output voltage reaches the set value.

First of all, it should be noted that the Boost DC-DC converter targeted by the method in this embodiment, as shown in FIG. 2 , includes a DC power supply E, an inductor L, a diode VD, a load R ₀ , a MOS transistor V, and a capacitor C;

The inductor L, diode VD and load R ₀ are sequentially connected between the positive and negative electrodes of the DC power supply E, and the diode VD is connected in the forward direction; the drain of the MOS transistor V is connected to the positive terminal of the diode VD, and the source is connected to the negative terminal of the DC power supply E. At the extreme, the gate is connected to the on-off time controller; the capacitor C is connected between the negative terminal of the diode VD and the negative terminal of the DC power supply E.

First assume that the inductor L and capacitor C values are large. When the controllable switch MOS tube V is in the on state, the DC power supply E _charges the inductor L, and the charging current is constant at Is, and the voltage on the capacitor C supplies power to the load R ₀ . Due to the large value of C, the output voltage u ₀ is basically kept at a constant value. Let V be in the on-state time t _on , be in the off-state time t _off , and the period T=t _on +t _off . The energy accumulated on the inductor L in the on-state phase is E×Is× _{t on} . When V is in the off state, the power supply E and the inductor L jointly charge the capacitor C and provide energy to the load. During this period, the energy released by the inductor is (U ₀ -E)I _s ×t _off , where U ₀ represents the desired output voltage. When the circuit is in steady state, from the conservation of energy, we can get:

E×I _s ×t _on =(U ₀ -E)×I _s ×t _off (1)

After simplification:

Wherein, T/t _off ≥1.

It can be seen that the output voltage is higher than the input voltage, so the converter acts as a boost.

The Boost DC-DC converter has two working modes, namely the continuous and discontinuous working modes of the inductor current. This embodiment only analyzes the continuous mode of the inductor current, and this analysis method and idea can also be used for the discontinuous mode of the inductor current. analyze. In the continuous mode of the inductor current, the circuit work process is divided into two turn-on and turn-off of the switch tube V. When the switch tube V is turned on, the inductor L stores energy. At this time, the load R ₀ does not rely on the power supply E to provide energy, but relies on the capacitor C to provide power. When the switch tube V is turned off, VD is turned on at this time, and the power supply E and the inductor L supply power to the load R ₀ and charge the capacitor C at the same time. In the continuous working mode, the two topologies of the Boost circuit are shown in Figure 3, which are the topology when the switch tube V is turned on, and the topology when the switch tube V is turned off.

For step S1:

Step S1 in this embodiment adopts the state space averaging method to model the Boost DC-DC converter system. Let the state variable be _x =[is u ₀ ] ^T , and denote u=E. Through the above analysis, it can be obtained that the state equations of the system in the two time periods [0, dT _s ] and [dT _s , T _s ] are as follows:

C₁＝[0 0]，

C₂＝[1 0]。in,

C ₁ =[0 0],

C ₂ =[1 0].

记d′＝1-d可得：Defined according to the average value of the switching period of the state variable:

Denote d′=1-d to get:

The same can be obtained:

Therefore:

Wherein A=dA ₁ +(1-d)A ₂ , B=dB ₁ +(1-d)B ₂ , C=dC ₁ +(1-d)C ₂ .

即：In steady state, there is

which is:

Get:

C＝[1-D 0]。here,

C=[1-D 0].

Therefore, the steady-state equation of the Boost DC-DC converter is obtained as follows:

To get the small-signal linear dynamic model, let:

Substitute into the state-space averaging equation and tidy up:

Ignoring the second-order AC small term, substituting the steady-state equation into the small-signal AC model is as follows:

Therefore, the AC small-signal state equation of the Boost DC-DC converter is:

In order to obtain the transfer function, the above state equation is Laplace transform, we get:

Solutions have to:

Therefore, the transfer function can be obtained as follows:

Substitute into the state equation to obtain the duty cycle-output open-loop transfer function:

Among them, L, C, R ₀ represent the inductance L, the capacitor C, the inductance value, capacitance value, and resistance value of the load R ₀ respectively, D represents the duty cycle, U ₀ represents the required output voltage, and s represents Boost DC- The complex frequency of the DC converter.

For step S2:

The basic parameters of the Boost DC-DC converter determined in step S2 in this embodiment include L, C, R ₀ , D, and U ₀ in equation (22), and the basic parameters are substituted into the duty cycle-output open loop Transfer the function and draw the corresponding Bode plot for post analysis.

The basic parameters of this embodiment include: duty cycle D=0.25, required output voltage U ₀ =10V, inductance L=20μH, capacitance C=500μF, input DC voltage E=5V, load R ₀ =10Ω, switching frequency =100kHz. Substituting into equation (22), the control-output transfer function can be obtained as:

The corresponding Bode diagram is drawn as shown in Figure 4.

It can be seen from the Bode diagram in Figure 4 that the phase margin is -5.34° and the gain crossover frequency is 2.84×10 ⁴ rad/s, so lead correction is required. In the following, lead correction will be performed using PD.

For step S3:

In this embodiment, in the step S3, the advance correction is performed on the Boost DC-DC converter by using the advance PD correction device, which specifically includes the steps:

S31. Determine the phase correction amount according to the Bode diagram of the Boost DC-DC converter, and use a lead PD correction device without gain to perform phase lead correction on the Boost DC-DC converter, so that the phase margin is greater than the set value;

S32. Analyze the phase-corrected Boost DC-DC converter, and use a correction device with gain k to perform gain correction on it, so that the gain crossover frequency reaches the set value.

The step S31 is specifically:

To make the phase margin larger than its set value by 45° (the phase correction amount is 50.34°), by estimation, let the phase increase of the lead PD correction device be θ=70°, and the transfer function of the lead PD correction device without gain is :

while the division factor

The relationship between the gain crossover frequency f _g and the switching frequency f _s is:

Therefore, the gain crossover angular frequency ω _g =2πf _g =1.26×10 ⁵ rad/s;

Let the maximum leading phase angle frequency of the leading PD correction device ω _m =ω _g =1.26×10 ⁵ rad/s, then the turning frequency of the leading PD correction transposition is obtained as:

于是得到

时间常数

so get

time constant

中，得到不含增益的超前PD校正装置的传递函数为：Substitute a and T into

, the transfer function of the lead PD correction device without gain is obtained as:

Step S32 is specifically:

Draw a Bode diagram for the Boost DC-DC converter after phase correction, and determine the amplitude L(ω _g ) of its gain crossover frequency point, so after adding the gain k, there is: L(ω _g )+20lgk=0, the calculation can be get the value of k.

More specifically, in order to determine the gain k, first draw the Bode diagram of the original Boost DC-DC converter after the correction device without gain is added, as shown in Figure 5.

It can be seen from Figure 5 that when the correction device without gain k is added, the phase margin is 50.1°, and the gain crossover frequency is 4.03×10 ⁴ rad/s. Therefore, after adding the gain k, the gain crossover frequency of the system should be 1.26×10 ⁵ rad/s. It can be seen from the figure that the amplitude of the figure is L(ω _g )=-10.6dB, so add k followed by:

L(ω _g )+20lgk=0 (27)

Find k = 3.3884.

Therefore, the PD correction device containing gain k is obtained as follows;

The Bode diagram of the Boost DC-DC converter after adding gain k is drawn again, as shown in Figure 6. As can be seen from Figure 6, when the PD correction device including gain k is added to the Boost DC-DC converter, the phase margin becomes 46°, and the gain crossover frequency is 1.26×10 ⁵ rad/s, reaching the set value.

For step S4:

The MATLAB/Simulink simulation model before the PID controller is not added to the Boost DC-DC converter system is shown in Figure 7. The lower left is the display of the measured amplitude (such as root mean square); the lower right is the measured waveform monitor. The MATLAB/Simulink toolbox is used to draw the dynamic curve of each state variable of the Boost DC-DC converter before the controller is added, as shown in Figure 8. From the figure, it can be obtained that the steady-state effective value of the output voltage u ₀ is 5.866V, which is less than 10V. In order to make u ₀ steady-state effective value is 10V. According to the analysis of steps S1 to S3, the corresponding Simulink PD closed-loop control simulation module is obtained as shown in Figure 9.

After simulation, it is found that the output voltage value is still less than 10V, so it is necessary to add a hysteresis PI correction device for voltage correction. The transfer function of the PI link is as follows:

According to experience, there is generally a correction angular frequency ω≤0.1ω _g , so ω=800rad/s can be taken here, and the transfer function of the PI link is obtained as:

So the complete PID closed-loop control simulation model is shown in Figure 10, and the corresponding output voltage waveform obtained through simulation is shown in Figure 11. As can be seen from Figure 11, the output voltage meets the specified requirement of 10V.

至输出

的传递函数即式(22)，G_m(s)为PWM脉冲宽度调制器的传递函数，H(s)为反馈分压网络的传递函数，G_c(s)为补偿网络(PID控制器)的传递函数。V_ref(s)表示参考信号，B(s)表示反馈信号，E(s)表示误差信号。其中，G_c(s)＝G_c1(s)+G_c2(s)。The closed-loop control process of the whole method can be summarized as shown in Figure 12. where G _vd (s) is the DC-DC duty cycle,

to output

The transfer function of is Eq. (22), G _m (s) is the transfer function of the PWM pulse width modulator, H (s) is the transfer function of the feedback voltage divider network, G _c (s) is the compensation network (PID controller) transfer function. _Vref (s) represents the reference signal, B(s) represents the feedback signal, and E(s) represents the error signal. Wherein, G _c (s)=G _c1 (s)+G _c2 (s).

The whole process is that the real phase margin, gain crossover frequency, and the error value E(s) of the output voltage steady-state rms value V ₀ (s) and its set value are transmitted to the feedback voltage divider network H(s), and the feedback voltage divider The network H(s) generates the corresponding feedback signal B(s) according to the error signal. Under the joint action of the reference signal V _ref (s), it is fed back to the compensation network G _c (s), and the output of the compensation network G _c (s) corresponds to The voltage signal Vc(s) is modulated by the PWM pulse width modulator, and then input to the Boost DC-DC converter, and the voltage is output after boosting and changing, thus forming a closed-loop control.

It should be noted that the Boost DC-DC converter to which the present invention is applicable is not limited to the circuit structure shown in FIG. 2 , and other modifications made on the basis of FIG. 2 are also applicable.

A PID control method for a Boost DC-DC converter provided by an embodiment of the present invention is to control the gain crossover frequency and phase margin of the Boost DC-DC converter through a PID controller (a leading PD correction device and a lag PI correction device). , The steady-state effective value of the output voltage is closed-loop adjusted, so that the output of the Boost DC-DC converter reaches the constant voltage DC of the required voltage value, and is efficient and accurate.

Example 2

An embodiment of the present invention provides a PID control system for a Boost DC-DC converter, which is applied to the PID control method described in Embodiment 1, including a Boost DC-DC converter and a PID controller;

The PID controller is used to determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use the lead PD correction device to perform lead correction on the Boost DC-DC converter, so that the phase margin is greater than the set value and the gain crossover frequency reaches set value;

The PID controller is also used to perform lag correction on the Boost DC-DC converter by using the lag PI correction device according to the steady-state effective value of the output voltage, so that the steady-state effective value of the output voltage reaches the set value;

The Boost DC-DC converter is used to convert the input initial DC voltage source into a boosted DC voltage source that reaches a preset voltage value under the control of the PID controller.

Specifically, the PID controller includes a leading PD correction device and a lag PI correction device;

The advanced PD correction device is used to determine the phase correction amount according to the Bode diagram of the Boost DC-DC converter, and perform phase and gain lead correction on the Boost DC-DC converter, so that the phase margin is greater than the set value and the gain crossover frequency. reach the set value;

The lag PI correction device is used to correct the voltage of the Boost DC-DC converter according to the steady-state effective value of the output voltage of the Boost DC-DC converter after being corrected by the leading PD correction device, so that the steady-state effective value of the output voltage reaches the set value .

Preferably, the leading PD correction device performs phase correction on the Boost DC-DC converter according to the PID control method of Embodiment 1;

The leading PD correction device performs gain correction on the Boost DC-DC converter according to the PID control method of Embodiment 1;

The hysteresis PI correction device performs voltage correction on the Boost DC-DC converter according to the PID control method of the first embodiment.

Since the PID control process has been described in detail in Embodiment 1, the specific control process of the PID controller will not be repeated in this embodiment.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (9)

1. a PID control method of Boost DC-DC converter, is characterized in that, comprises the steps: S1. The Boost DC-DC converter is modeled by the state space averaging method, and the duty cycle-output open-loop transfer function of the Boost DC-DC converter is obtained; S2. determine the basic parameters of the Boost DC-DC converter, substitute the basic parameters into the duty cycle-output open-loop transfer function and draw the corresponding Bode diagram; S3. Determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use the lead PD correction device to perform lead correction on the Boost DC-DC converter, so that its phase margin is greater than the set value and the gain crossover frequency reach the set value; S4. Determine the steady-state effective value of the output voltage of the Boost DC-DC converter after PD correction; S5. According to the steady-state effective value of the output voltage, use the lag PI correction device to perform lag correction on the Boost DC-DC converter, so that the steady-state effective value of the output voltage reaches the set value; The step S5 is specifically: Determine whether the steady-state effective value of the output voltage is less than its set value, if not, do not correct, if so, use a hysteresis PI correction device to perform voltage correction, and the transfer function of the hysteresis PI correction device is:

According to experience, there is a correction angular frequency ω≤0.1ω _g , s represents the complex frequency of the Boost DC-DC converter, the gain crossover angular frequency ω _g =2πf _g , and f _g represents the gain crossover frequency. 2. the PID control method of a kind of Boost DC-DC converter as claimed in claim 1, is characterized in that: The Boost DC-DC converter includes a DC power supply, an inductor, a diode and a load, a MOS tube, and a capacitor; The inductor, the diode and the load are sequentially connected between the positive and negative poles of the DC power supply, and the diode is connected in a forward direction; The drain of the MOS tube is connected to the positive terminal of the diode, the source is connected to the negative terminal of the DC power supply, and the gate is connected to the on-off time controller; the capacitor is connected between the negative terminal of the diode and the negative terminal of the DC power supply; The duty cycle-output open-loop transfer function is expressed as:

Wherein, L, C, R ₀ represent the inductance, the capacitor, the inductance value, capacitance value, and resistance value of the load respectively, D represents the duty cycle, U ₀ represents the required output voltage, and s represents the Boost The complex frequency of the DC-DC converter. 3. the PID control method of a kind of Boost DC-DC converter as claimed in claim 2, is characterized in that, in described step S3, described utilizes the advanced PD correction device to carry out the described Boost DC-DC converter. Advance correction, including steps: S31. Determine the phase correction amount according to the Bode diagram of the Boost DC-DC converter, and use a lead PD correction device without gain to perform phase lead correction on the Boost DC-DC converter, so that the phase margin is greater than the setting value; S32. Analyze the phase-corrected Boost DC-DC converter, and use a correction device with gain k to perform gain correction on it, so that the gain crossover frequency reaches a set value. 4. the PID control method of a kind of Boost DC-DC converter as claimed in claim 3, is characterized in that, described step S31 is specially: To make the phase margin larger than its set value, let the phase increase of the leading PD correction device be θ, and the transfer function of the leading PD correction device without gain is:

while the division factor

The relationship between the gain crossover frequency f _g and the switching frequency f _s is:

Then, the gain crossover angular frequency ω _g =2πf _g ; Let the maximum leading phase angle frequency of the leading PD correction device ω _m =ω _g , then the turning frequency of the leading PD correction transposition is obtained as:

so get

T is the time constant; Substitute a and T into

, the transfer function of the lead PD correction device without gain is obtained. 5. the PID control method of a kind of Boost DC-DC converter as claimed in claim 4, is characterized in that, described step S32 is specially: A Bode diagram is drawn for the phase-corrected Boost DC-DC converter, and the amplitude L(ω _g ) of the gain crossover frequency point is determined, so after adding the gain k, there are: L(ω _g )+20lgk=0, Calculate the value of k. 6. a PID control system of Boost DC-DC converter, is characterized in that: comprise Boost DC-DC converter and PID controller; The PID controller is used to determine the correction amount according to the Bode diagram of the Boost DC-DC converter, and use the lead PD correction device to perform lead correction on the Boost DC-DC converter, so that its phase margin is greater than the set value and the gain crossover frequency reaches the set value; The PID controller is also used to perform lag correction on the BoostDC-DC converter by using a lag PI correction device according to the steady-state effective value of the output voltage, so that the steady-state effective value of the output voltage reaches a set value; The Boost DC-DC converter is used to convert the input initial DC voltage source into a boosted DC voltage source that reaches a preset voltage value under the control of the PID controller; The process that the hysteresis PI correction device performs voltage correction on the Boost DC-DC converter is as follows: Determine whether the steady-state effective value of the output voltage is less than its set value, if not, do not correct, if so, use a hysteresis PI correction device to perform voltage correction, and the transfer function of the hysteresis PI correction device is:

According to experience, there is a correction angular frequency ω≤0.1ω _g , s represents the complex frequency of the Boost DC-DC converter, the gain crossover angular frequency ω _g =2πf _g , and f _g represents the gain crossover frequency. 7. the PID control system of a kind of Boost DC-DC converter as claimed in claim 6, is characterized in that: The Boost DC-DC converter includes a DC power supply, an inductor, a diode and a load, a MOS tube, and a capacitor; The inductor, the diode, and the load are sequentially connected between the positive and negative poles of the DC power supply, and the diode is connected in a forward direction; The drain of the MOS tube is connected to the positive terminal of the diode, the source is connected to the negative terminal of the DC power supply, and the gate is connected to the on-off time controller; the capacitor is connected between the negative terminal of the diode and the negative terminal of the DC power supply; The duty cycle-output open-loop transfer function is expressed as:

Wherein, L, C, R ₀ represent the inductance, the capacitor, the inductance value, capacitance value, and resistance value of the load respectively, D represents the duty cycle, U ₀ represents the required output voltage, and s represents the Boost The complex frequency of the DC-DC converter. 8. the PID control system of a kind of Boost DC-DC converter as claimed in claim 7, is characterized in that: described PID controller comprises leading PD correction device and lag PI correction device; The leading PD correction device is used to determine the phase correction amount according to the Bode diagram of the Boost DC-DC converter, and perform phase and gain lead correction on the Boost DC-DC converter, so that the phase margin is greater than the setting value and gain crossover frequency reach the set value; The lag PI correction device is configured to perform voltage correction on the Boost DC-DC converter according to the steady-state effective value of the output voltage of the Boost DC-DC converter after correction by the leading PD correction device, so that the output voltage of the Boost DC-DC converter is stable The effective value reaches the set value. 9. the PID control system of a kind of Boost DC-DC converter as claimed in claim 8, is characterized in that: The process of performing phase correction on the Boost DC-DC converter by the advanced PD correction device is as follows: To make the phase margin larger than its set value, let the phase increase of the leading PD correction device be θ, and the transfer function of the leading PD correction device without gain is:

while the division factor

The relationship between the gain crossover frequency f _g and the switching frequency f _s is:

Then, the gain crossover angular frequency ω _g =2πf _g ; Let the maximum leading phase angle frequency of the leading PD correction device ω _m =ω _g , then the turning frequency of the leading PD correction transposition is obtained as:

so get

T is the time constant; Substitute a and T into

, the transfer function of the leading PD correction device without gain is obtained; The process that the advance PD correction device performs gain correction on the Boost DC-DC converter is as follows: A Bode diagram is drawn for the phase-corrected Boost DC-DC converter, and the amplitude L(ω _g ) of the gain crossover frequency point is determined, so after adding the gain k, there are: L(ω _g )+20lgk=0, Calculate the value of k.

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