CN113114136B - A Gradient Power Amplifier Based on Adaptive Predictive Control and Its Design Method - Google Patents

Abstract

The invention relates to a gradient power amplifier based on adaptive predictive control and a design method thereof, belonging to the field of electronic circuits. A gradient power amplifier device based on adaptive predictive control mainly includes a four-arm power circuit and a fast feedback predictive circuit; the microprocessor adjusts the PID control parameters by adjusting the digital potentiometer in the PID circuit according to the response curve output by the gradient power amplifier. Adjust to the optimum and calculate the system output response time constant τ; the microprocessor adjusts the resistance value of the digital potentiometer in the fast prediction circuit to match the prediction coefficient with the system output response time constant τ; then the fast prediction circuit and the PID The circuits are cascaded to realize adaptive parameter matching of the gradient power amplifier in different application scenarios, and fast predictive control of the output signal of the control circuit, thereby improving the output response speed and accuracy of the gradient power amplifier.

Description

A Gradient Power Amplifier Based on Adaptive Predictive Control and Its Design Method

technical field

The invention belongs to the field of electronic circuits, and relates to a gradient power amplifier based on adaptive predictive control and a design method thereof.

Background technique

As the core component of the MRI system, the gradient amplifier receives the gradient signals output by the spectrometer in the three directions of the X-axis, Y-axis, and Z-axis with a certain time sequence for power amplification, and generates corresponding spatial encoding gradients in space through the gradient coil drive current. The magnetic field realizes the spatial positioning of the imaging voxel. The gradient amplifier generates a changing gradient magnetic field around the gradient coil through the changing current. The ultimate goal of the gradient amplifier is to provide a high-performance gradient magnetic field for MRI. The development of gradient technology can effectively improve the imaging speed and quality. The maximum value that the gradient magnetic field can reach is the strength of the gradient magnetic field. The increase of the gradient magnetic field strength can effectively improve the spatial resolution of imaging, and perform imaging with thinner layers. Therefore, the design of high-performance gradient amplifiers has become the top priority of MRI system design.

In recent years, some research institutions and manufacturers have begun to study the control system of digital circuit power amplifiers, and have achieved preliminary results in the research of some control methods and structures, but the performance of the control system is far from satisfying high-level requirements. Quality imaging is required and cannot be put into practical application. The circuit structure adopted by the gradient amplifiers already on the market is generally a double H-bridge topology, and the driving current is provided for the gradient coil through a digital switch. There are different control methods for this structure, but they generally focus on closed-loop control, using the classic PID control algorithm, and improving the algorithm on this basis in order to achieve the required performance, such as state feedback, feedforward control, Delay compensation, etc.

The key issues of the gradient power amplifier are the high precision of the output gradient current signal, the fast tracking output and the adaptive parameter setting adjustment for different application systems. At present, the classic PID control algorithm still faces many problems. In the actual application of nuclear magnetic resonance imaging system, it is urgent to study a set of gradient power amplifier system with fast, stable, high-precision and adaptive adjustment of control parameters. need.

Contents of the invention

In view of this, the object of the present invention is to provide a gradient power amplifier based on adaptive predictive control and a design method thereof. It can realize the fast and high-precision current output of the gradient power amplifier, solve the problem of slow response speed and low precision of the current output of the gradient power amplifier, and effectively improve the output current accuracy and response speed of the gradient power amplifier. The resonance imaging system needs to be able to realize adaptive parameter adjustment to match the system parameters to achieve optimal control.

To achieve the above object, the present invention provides the following technical solutions:

A gradient power amplifier based on adaptive predictive control and its design method, including sequentially connected four-arm power circuits and fast feedback predictive circuits;

The four-bridge arm power circuit consists of a four-bridge arm drive circuit, a four-bridge arm switch circuit, an LC filter circuit and an H-bridge circuit for forward and reverse current switching connected in sequence;

The fast feedback prediction circuit includes an amplifier realized by analog circuits connected in sequence, a fast prediction circuit, a PID circuit, a comparator, and a microprocessor, FPGA, DAC converter, digital potentiometer and adjustable potentiometer and ADC converter.

A gradient power amplifier based on adaptive predictive control and a design method thereof, the method comprising the following steps:

S1: The microprocessor closes K1, opens K2, and disconnects the fast prediction circuit from the PID circuit. The microprocessor adjusts the digital potentiometer in the PID circuit according to the feedback error signal to realize the automatic adjustment of the relevant parameters of the PID circuit, and obtain the best Gradient power amplifier output response time parameter τ under optimal PID control;

S2: The microprocessor opens K1, closes K2, connects the fast prediction circuit in series with the PID circuit, calculates the resistance value of the digital potentiometer in the fast prediction circuit according to the output response time parameter τ of the gradient power amplifier, and the microprocessor adjusts quickly The parameters of the digital potentiometer in the second-stage amplification circuit and the third-stage differential circuit of the prediction circuit make the prediction time constant in the fast prediction circuit match the output response time parameter τ of the gradient power amplifier, so as to realize the fast feedback error signal predicted output;

S3: The potentiometer is adjusted manually. After the ADC converter, the microprocessor can perceive the manual parameter setting in real time, thereby controlling the digital potentiometer in the PID and fast prediction circuit, and realizing the manual intervention of the output control parameters of the gradient power amplifier. .

Optionally, the S1 specifically includes:

S11: The microprocessor calculates the DC bus voltage V _DC according to the set value V _SET , and the relational expression between the two is:

In formula (1), K _CONVERT is the conversion coefficient between the set value and the output current, R _coil is the load resistance, and D is the duty cycle, which is 60%;

According to the size of the output current, the microprocessor outputs the signal to the output voltage adjustment terminal of the programmable DC power supply through the DAC and the amplifier, and dynamically adjusts the DC bus voltage to the expected value V _DC ;

S12: The microprocessor automatically adjusts the digital potentiometer of the PID circuit according to the feedback error signal V _ERROR , thereby changing the proportional coefficient K _p , the integral coefficient K _i , and the differential coefficient K _d in the PID circuit in real time;

The relationship expression between PID circuit output V _OUT and V _ERROR is:

S13: The output V _OUT of the PID circuit is compared with four 90° phase-shifted sawtooth waves to generate four 90° phase-shifted PWM waves that are sent to the FPGA. The bridge arm drive circuit controls the output current of the gradient power amplifier by adjusting the PWM duty cycle, and the FPGA controls the switching of the H-bridge circuit switch by judging the positive and negative polarity of the set value signal, thereby realizing the direction control of the output current ;

S14: According to the output current rise and fall time, overshoot and oscillation time under different PID control parameters, debug and adjust to obtain the output response time parameter τ under the optimal PID control of the system.

Optionally, in said S2, calculating the system control parameters matching the system according to the system parameters specifically includes:

S21: The gradient power amplifier output current response time parameter τ is equivalent to an RC charging signal with a first-order exponential rate change, τ=R ₁ C ₁ ;

In formula (3), V ₀ is the initial voltage of V _ERROR , V _F is the stable voltage, V ₁ is the output of the first-stage amplifier circuit, V _T1 is the input of the first-stage operational amplifier, and V _T2 is the output of the first-stage operational amplifier;

S22: After the feedback error signal passes through the first-stage voltage follower circuit, it is sent to the second-stage amplifying circuit, wherein the magnification of the second-stage amplifying circuit is controlled by the microprocessor by adjusting the digital potentiometer dcp1,

The output V ₂ of the second-stage amplifier circuit is:

In formula (5), R _dcp1 is the resistance value of digital potentiometer dcp1, and R ₃ is the resistance resistance value of the inverting input terminal;

S23: After the signal passes through the third-stage differential circuit, we get:

Adjust the resistance value R _dcp2 of the digital potentiometer dcp2 in the differential circuit so that the time constant of the differential circuit is consistent with the equivalent feedback error signal, so R _dcp2 C ₂ =R ₁ C ₁ ;

The output _V3 of the third stage differential circuit is:

S24: Add the output V ₃ of the third-stage differential circuit and the output V ₁ of the first-stage amplifying circuit to the non-inverting input terminal V _IN4+ of the fourth-stage amplifying circuit, as shown in the following formula:

In formula (8), R ₈ and R ₁₁ are the resistance value of the addition circuit, satisfying 2R ₈ =R ₁₁ ;

Adjust the resistance value of digital potentiometer dcp1 to satisfy R _dcp1 = R ₃ :

After the amplification of the final op amp, we get:

In formula (10), V _out is the output of the fast prediction circuit, and R ₉ and R ₁₀ are the resistance values of the amplifier circuit, satisfying 2R ₉ =R ₁₀ ;

have to:

V _out =V _F (11)

The fast prediction circuit can realize the fast prediction output of the output current feedback signal;

S25: The microprocessor selects the switch to open K1 and close K2 to cascade the fast prediction circuit and the PID circuit, and the output of the fast prediction circuit is directly sent to the PID circuit to improve the response speed of the output control of the gradient power amplifier.

Optionally, the S3 specifically includes:

S31: Adjust the adjustable potentiometer manually, and the microprocessor can sense the PID and quickly predict the manual parameter setting in the circuit through the ADC converter in real time, and calculate the corresponding digital potentiometer contact position parameter;

S32: The microprocessor controls the contact of the digital potentiometer in the PID and fast prediction circuit to a corresponding position, thereby realizing the manual intervention and adjustment of the output current control parameters of the gradient power amplifier.

The beneficial effect of the present invention is that: in the present invention, the microprocessor adjusts the fast prediction circuit access control circuit through the selection switch, and on the basis of achieving optimal PID control, the fast prediction circuit and the PID circuit are cascaded, and the microprocessor obtains the Adjust the resistance value of the digital potentiometer of the second-stage amplifying circuit and the third-stage differential circuit in the rapid prediction circuit to make the fast prediction circuit parameters match the system parameters, realize the rapid prediction of the control parameters in the control process, and improve the system control parameters. The control effect of the control system greatly broadens the application scenarios of the designed method; based on the dynamic parameter adjustment realized by the adjustable potentiometer, ADC converter, microprocessor, and digital potentiometer, the circuit parameters can be quickly predicted by manual adjustment, and realized in different Manual intervention and adjustment of gradient power amplifiers in application scenarios, real-time adjustment of output current control effects.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from It is taught in the practice of the present invention. The objects and other advantages of the invention may be realized and attained by the following specification.

Description of drawings

In order to make the purpose of the present invention, technical solutions and advantages clearer, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

Figure 1 is a schematic block diagram of the rapid prediction circuit;

Fig. 2 is the overall scheme diagram of the fast predictive control circuit;

Fig. 3 is an overall block diagram of the adaptive fast predictive control gradient power amplifier hardware system.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments are only schematically illustrating the basic concept of the present invention, and the following embodiments and the features in the embodiments can be combined with each other in the case of no conflict.

Wherein, the accompanying drawings are for illustrative purposes only, and represent only schematic diagrams, rather than physical drawings, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, Enlargement or reduction does not represent the size of the actual product; for those skilled in the art, it is understandable that certain known structures and their descriptions in the drawings may be omitted.

In the drawings of the embodiments of the present invention, the same or similar symbols correspond to the same or similar components; , "front", "rear" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred devices or elements must It has a specific orientation, is constructed and operated in a specific orientation, so the terms describing the positional relationship in the drawings are for illustrative purposes only, and should not be construed as limiting the present invention. For those of ordinary skill in the art, the understanding of the specific meaning of the above terms.

Figure 1 is a block diagram of part of the rapid prediction circuit; Figure 2 is the overall scheme of the rapid prediction control circuit; Figure 3 is the overall block diagram of the adaptive rapid prediction control gradient power amplifier hardware system. A gradient power amplifier device based on adaptive fast predictive control is composed of a four-arm power circuit and a fast feedback predictive circuit. The four-arm power circuit includes a sequentially connected four-arm drive circuit, four-arm switch circuit, and LC filter circuit. It is composed of an H-bridge circuit with positive and negative current switching; the fast feedback prediction circuit includes amplifiers, fast prediction circuits, PID circuits, comparators, and microprocessors, FPGAs, DAC converters, digital potentiometers and The adjustable potentiometer and ADC converter, and the fast prediction circuit include a first-stage follower circuit, a second-stage amplifying circuit, a third-stage differential circuit, and a fourth-stage amplifying circuit connected in sequence.

The invention provides a gradient power amplifier based on adaptive predictive control and a design method thereof, the method comprising the following steps:

S1: The microprocessor closes K1, opens K2, and disconnects the fast prediction circuit from the PID circuit. The microprocessor adjusts the digital potentiometer in the PID circuit according to the feedback error signal to realize the automatic adjustment of the relevant parameters of the PID circuit, and obtain the best Gradient power amplifier output response time parameter τ under optimal PID control;

S2: The microprocessor opens K1, closes K2, connects the fast prediction circuit in series with the PID circuit, calculates the resistance value of the digital potentiometer in the fast prediction circuit according to the output response time parameter τ of the gradient power amplifier, and the microprocessor adjusts quickly The parameters of the digital potentiometer in the second-stage amplification circuit and the third-stage differential circuit of the prediction circuit make the prediction time constant in the fast prediction circuit match the output response time parameter τ of the gradient power amplifier, so as to realize the fast feedback error signal predicted output;

S3: The potentiometer is adjusted manually. After the ADC converter, the microprocessor can perceive the manual parameter setting in real time, thereby controlling the digital potentiometer in the PID and fast prediction circuit, and realizing the manual intervention of the output control parameters of the gradient power amplifier. .

In step S1, specifically include:

S11: The microprocessor calculates the DC bus voltage V _DC according to the set value V _SET , and the relational expression between the two is:

In formula (1), K _CONVERT is the conversion coefficient between the set value and the output current, R _coil is the load resistance, and D is the duty cycle, which is 60%;

According to the size of the output current, the microprocessor outputs the signal to the output voltage adjustment terminal of the programmable DC power supply through the DAC and the amplifier, and dynamically adjusts the DC bus voltage to the expected value V _DC ;

S12: The microprocessor automatically adjusts the digital potentiometer of the PID circuit according to the feedback error signal V _ERROR , thereby changing the proportional coefficient K _p , the integral coefficient K _i , and the differential coefficient K _d in the PID circuit in real time;

The relationship expression between PID circuit output V _OUT and V _ERROR is:

S13: The output V _OUT of the PID circuit is compared with four 90° phase-shifted sawtooth waves to generate four 90° phase-shifted PWM waves that are sent to the FPGA. The bridge arm drive circuit controls the output current of the gradient power amplifier by adjusting the PWM duty cycle, and the FPGA controls the switching of the H-bridge circuit switch by judging the positive and negative polarity of the set value signal, thereby realizing the direction control of the output current ;

S14: According to the output current rise and fall time, overshoot and oscillation time under different PID control parameters, debug and adjust to obtain the output response time parameter τ under the optimal PID control of the system.

In step S2, the system control parameters that match the system are calculated according to the system parameters and specifically include:

S21: The gradient power amplifier output current response time parameter τ is equivalent to an RC charging signal with a first-order exponential rate change, ie τ=R ₁ C ₁ .

In formula (3), V ₀ is the initial voltage of V _ERROR , V _F is the stable voltage, V ₁ is the output of the first-stage amplifier circuit, V _T1 is the input of the first-stage operational amplifier, and V _T2 is the output of the first-stage operational amplifier;

S22: After the feedback error signal passes through the first-stage voltage follower circuit, it is sent to the second-stage amplifying circuit, wherein the magnification of the second-stage amplifying circuit is controlled by the microprocessor by adjusting the digital potentiometer dcp1,

That is, the output V ₂ of the second-stage amplifier circuit is:

In formula (5), R _dcp1 is the resistance value of digital potentiometer dcp1, and R ₃ is the resistance resistance value of the inverting input terminal;

S23: After the signal passes through the third-stage differential circuit, it can be obtained:

Adjust the resistance value R _dcp2 of the digital potentiometer dcp2 in the differential circuit so that the time constant of the differential circuit is consistent with the equivalent feedback error signal, so R _dcp2 C ₂ =R ₁ C ₁ ;

The output _V3 of the third stage differential circuit is:

S24: Add the output V ₃ of the third-stage differential circuit and the output V ₁ of the first-stage amplifying circuit to the non-inverting input terminal V _IN4+ of the fourth-stage amplifying circuit, as shown in the following formula:

In formula (8), R ₈ and R ₁₁ are the resistance value of the addition circuit, satisfying 2R ₈ =R ₁₁ ;

Adjust the resistance value of digital potentiometer dcp1 to satisfy R _dcp1 = R ₃ :

After the amplification of the final op amp, we can get:

In formula (10), V _out is the output of the fast prediction circuit, and R ₉ and R ₁₀ are the resistance values of the amplifier circuit, satisfying 2R ₉ =R ₁₀ ;

That is:

V _out =V _F (11)

That is, the fast prediction circuit can realize the fast prediction output of the output current feedback signal.

S25: The microprocessor selects the switch to open K1 and close K2 to cascade the fast prediction circuit and the PID circuit, and the output of the fast prediction circuit is directly sent to the PID circuit to improve the response speed of the output control of the gradient power amplifier.

In step S3, specifically include:

S31: Adjust the adjustable potentiometer manually, and the microprocessor can sense the PID and quickly predict the manual parameter setting in the circuit through the ADC converter in real time, and calculate the corresponding digital potentiometer contact position parameter;

S32: The microprocessor controls the contact of the digital potentiometer in the PID and fast prediction circuit to a corresponding position, thereby realizing the manual intervention and adjustment of the output current control parameters of the gradient power amplifier.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims (5)

1. a design method based on the gradient power amplifier of adaptive predictive control, it is characterized in that: the method may further comprise the steps: S1: The microprocessor closes K1, opens K2, and disconnects the fast prediction circuit from the PID circuit. The microprocessor adjusts the digital potentiometer in the PID circuit according to the feedback error signal to realize the automatic adjustment of the relevant parameters of the PID circuit, and obtain the best Gradient power amplifier output response time parameter τ under optimal PID control; S2: The microprocessor opens K1, closes K2, connects the fast prediction circuit in series with the PID circuit, calculates the resistance value of the digital potentiometer in the fast prediction circuit according to the output response time parameter τ of the gradient power amplifier, and the microprocessor adjusts quickly The resistance value of the digital potentiometer in the second-stage amplifying circuit and the third-stage differential circuit of the prediction circuit makes the prediction time constant in the fast prediction circuit match the output response time parameter τ of the gradient power amplifier, so as to realize the accuracy of the feedback error signal fast prediction output; S3: The adjustable potentiometer is adjusted manually. After the ADC converter, the microprocessor can perceive the parameter setting of the adjustable potentiometer in real time, thereby controlling the digital potentiometer in the PID and fast prediction circuit to realize the gradient power amplifier. Manual intervention of output control parameters. 2. the design method of a kind of gradient power amplifier based on adaptive predictive control according to claim 1, is characterized in that: described S1 specifically comprises: S11: The microprocessor calculates the DC bus voltage V _DC according to the set value V _SET , and the relational expression between the two is:

In formula (1), K _CONVERT is the conversion coefficient between the set value and the output current, R _coil is the load resistance, and D is the duty cycle, which is 60%; According to the size of the output current, the microprocessor outputs the signal to the output voltage adjustment terminal of the programmable DC power supply through the DAC and the amplifier, and dynamically adjusts the DC bus voltage to the expected value V _DC ; S12: The microprocessor automatically adjusts the digital potentiometer of the PID circuit according to the feedback error signal V _ERROR , thereby changing the proportional coefficient K _p , the integral coefficient K _i , and the differential coefficient K _d in the PID circuit in real time; The relationship expression between PID circuit output V _OUT and V _ERROR is:

S13: The output V _OUT of the PID circuit is compared with four 90° phase-shifted sawtooth waves to generate four 90° phase-shifted PWM waves that are sent to the FPGA. The bridge arm drive circuit controls the output current of the gradient power amplifier by adjusting the PWM duty cycle, and the FPGA controls the switching of the H-bridge circuit switch by judging the positive and negative polarity of the set value signal, thereby realizing the direction control of the output current ; S14: According to the output current rise and fall time, overshoot and oscillation time under different PID control parameters, debug and adjust to obtain the output response time parameter τ under the optimal PID control of the system. 3. the design method of a kind of gradient power amplifier based on adaptive predictive control according to claim 1, is characterized in that: in described S2, according to system parameter calculation, the system control parameter that matches with system specifically comprises: S21: The gradient power amplifier output current response time parameter τ is equivalent to an RC charging signal with a first-order exponential rate change, that is, τ=R ₁ C ₁ ;

In formula (3), V ₀ is the initial voltage of V _ERROR , V _F is the stable voltage, V ₁ is the output of the first-stage amplifier circuit, V _T1 is the input of the first-stage operational amplifier, and V _T2 is the output of the first-stage operational amplifier; S22: After the feedback error signal passes through the first-stage voltage follower circuit, it is sent to the second-stage amplifying circuit, wherein the magnification of the second-stage amplifying circuit is controlled by the microprocessor by adjusting the digital potentiometer dcp1

The output V ₂ of the second-stage amplifier circuit is:

In formula (5), R _dcp1 is the resistance value of digital potentiometer dcp1, and R ₃ is the resistance resistance value of the inverting input terminal; S23: After the signal passes through the third-stage differential circuit, we get:

Adjust the resistance value R _dcp2 of the digital potentiometer dcp2 in the differential circuit so that the time constant of the differential circuit is consistent with the equivalent feedback error signal, so R _dcp2 C ₂ =τ=R ₁ C ₁ ; The output _V3 of the third stage differential circuit is:

S24: Add the output V ₃ of the third-stage differential circuit and the output V ₁ of the first-stage amplifying circuit to the non-inverting input terminal V _IN4+ of the fourth-stage amplifying circuit, as shown in the following formula:

In formula (8), R ₈ and R ₁₁ are the resistance value of the addition circuit, satisfying 2R ₈ =R ₁₁ ; Adjust the resistance value of digital potentiometer dcp1 to satisfy R _dcp1 = R ₃ :

After the amplification of the final op amp, we get:

In formula (10), V _out is the output of the fast prediction circuit, and R ₉ and R ₁₀ are the resistance values of the amplifier circuit, satisfying 2R ₉ =R ₁₀ ; have to: V _out =V _F (11) The fast prediction circuit can realize the fast prediction output of the output current feedback signal; S25: The microprocessor selects the switch to open K1 and close K2 to cascade the fast prediction circuit and the PID circuit, and the output of the fast prediction circuit is directly sent to the PID circuit to improve the response speed of the output control of the gradient power amplifier. 4. the design method of a kind of gradient power amplifier based on adaptive predictive control according to claim 1, is characterized in that: described S3 specifically comprises: S31: Adjust the adjustable potentiometer manually, and the microprocessor can sense the PID and quickly predict the manual parameter setting in the circuit through the ADC converter in real time, and calculate the corresponding digital potentiometer contact position parameter; S32: The microprocessor controls the contact of the digital potentiometer in the PID and fast prediction circuit to a corresponding position, thereby realizing the manual intervention and adjustment of the output current control parameters of the gradient power amplifier. 5. A gradient power amplifier, designed according to the method claimed in claim 2, is characterized in that: comprising four bridge arm power circuits and fast feedback predictive circuits connected successively; The four-bridge arm power circuit consists of a four-bridge arm drive circuit, a four-bridge arm switch circuit, an LC filter circuit and an H-bridge circuit for forward and reverse current switching connected in sequence; The fast feedback prediction circuit includes an amplifier realized by sequentially connected analog circuits, a fast prediction circuit, a PID circuit, a comparator, and a microprocessor, FPGA, DAC converter, digital potentiometer, adjustable potentiometer and ADC converter; The microprocessor adjusts the fast prediction circuit to be connected to the control circuit through the selection switch. On the basis of achieving the optimal PID control, the fast prediction circuit and the PID circuit are cascaded, and the microprocessor adjusts the first prediction circuit in the fast prediction circuit according to the obtained system control parameters. The resistance value of the digital potentiometer of the two-stage amplifying circuit and the third-stage differential circuit makes the rapid prediction circuit parameters match the system parameters, and realizes the rapid prediction of the control parameters in the control process.

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