CN113114136B - Gradient power amplifier based on self-adaptive prediction control and design method thereof - Google Patents

Gradient power amplifier based on self-adaptive prediction control and design method thereof Download PDF

Info

Publication number
CN113114136B
CN113114136B CN202110419600.1A CN202110419600A CN113114136B CN 113114136 B CN113114136 B CN 113114136B CN 202110419600 A CN202110419600 A CN 202110419600A CN 113114136 B CN113114136 B CN 113114136B
Authority
CN
China
Prior art keywords
circuit
prediction
pid
output
power amplifier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110419600.1A
Other languages
Chinese (zh)
Other versions
CN113114136A (en
Inventor
王平
田训
柳学功
李锡涛
王慧悦
梁家祺
武超
阎鑫龙
李倩文
陈靖翰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chongqing University
Original Assignee
Chongqing University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chongqing University filed Critical Chongqing University
Priority to CN202110419600.1A priority Critical patent/CN113114136B/en
Publication of CN113114136A publication Critical patent/CN113114136A/en
Application granted granted Critical
Publication of CN113114136B publication Critical patent/CN113114136B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

The invention relates to a gradient power amplifier based on self-adaptive prediction control and a design method thereof, belonging to the field of electronic circuits. A gradient power amplifier device based on self-adaptive prediction control mainly comprises a four-bridge arm power circuit and a rapid feedback prediction circuit; the microprocessor adjusts PID control parameters to be optimal by adjusting a digital potentiometer in the PID circuit according to a response curve output by the gradient power amplifier, and calculates a system output response time constant tau; the microprocessor realizes the matching of a prediction coefficient and a system output response time constant tau by adjusting the resistance value of a digital potentiometer in the quick prediction circuit; and then the rapid prediction circuit is cascaded with the PID circuit, so that the adaptive parameter matching of the gradient power amplifier under different application scenes is realized, and the rapid prediction control of the output signal of the control circuit is realized, thereby improving the output response speed and the accuracy of the gradient power amplifier.

Description

Gradient power amplifier based on self-adaptive prediction control and design method thereof
Technical Field
The invention belongs to the field of electronic circuits, and relates to a gradient power amplifier based on self-adaptive prediction control and a design method thereof.
Background
The gradient amplifier is used as a core component of the MRI system, receives gradient signals which are output by a spectrometer and have a certain time sequence and in three directions of an X axis, a Y axis and a Z axis, carries out power amplification, and generates a corresponding spatial coding gradient magnetic field in space through a gradient coil driving current to realize the spatial positioning of imaging voxels. The gradient amplifier generates a variable gradient magnetic field around the gradient coil by a variable current, the final purpose of the gradient amplifier is to provide a high-performance gradient magnetic field for MRI, and the development of the gradient technology can effectively improve the imaging speed and quality. The maximum value which can be reached by the gradient magnetic field is the strength of the gradient magnetic field, the spatial resolution of imaging can be effectively improved by increasing the strength of the gradient magnetic field, and imaging of thinner layers is carried out. The design of high performance gradient amplifiers is also an important factor in the design of MRI systems.
In recent years, some research institutions and manufacturers have started research on digital circuit power amplifier control systems, and have primary effect on the research on some control methods and structures, but the performance of the control systems is far from meeting the requirement of high-quality imaging, and the control systems cannot be put into practical application. The circuit structure adopted by the gradient amplifier on the market is generally a double H-bridge topology structure, and the gradient coil is provided with a driving current through a digital switch. The control method for such a structure is different, but generally focuses on closed-loop control, adopts a classical PID control algorithm, and performs algorithm improvement on the basis of the classical PID control algorithm so as to achieve the required performance, such as state feedback, feedforward control, delay compensation and the like.
The key problems of the gradient power amplifier are high precision and quick tracking output of output gradient current signals and self-adaptive parameter setting adjustment aiming at different application systems. At present, a classical PID control algorithm still faces many problems, and in the application of an actual nuclear magnetic resonance imaging system, a set of gradient power amplifier systems which are rapid, stable, high in precision and self-adaptive in control parameter adjustment are researched, so that the urgent need in the application at present is met.
Disclosure of Invention
In view of the above, the present invention provides a gradient power amplifier based on adaptive prediction control and a design method thereof. The method can realize the fast and high-precision current output of the gradient power amplifier, solves the problems of slow response speed and low precision of the current output of the gradient power amplifier, effectively improves the output current precision and the response speed of the gradient power amplifier, and can realize the self-adaptive parameter adjustment aiming at the requirements of different nuclear magnetic resonance imaging systems applied to the gradient power amplifier, so that the gradient power amplifier is matched with system parameters to achieve the optimal control.
In order to achieve the purpose, the invention provides the following technical scheme:
a gradient power amplifier based on adaptive prediction control and a design method thereof comprise a four-bridge arm power circuit and a rapid feedback prediction circuit which are sequentially connected;
the four-bridge-arm power circuit comprises a four-bridge-arm driving circuit, a four-bridge-arm switching circuit, an LC filter circuit and a current positive and negative phase switching H-bridge circuit which are sequentially connected;
the rapid feedback prediction circuit comprises an amplifier, a rapid prediction circuit, a PID circuit, a comparator, a microprocessor, an FPGA, a DAC converter, a digital potentiometer, an adjustable potentiometer and an ADC which are sequentially connected and realized by an analog circuit.
A gradient power amplifier based on adaptive prediction control and a design method thereof are disclosed, the method comprises the following steps:
s1: the microprocessor closes K1 and opens K2, the rapid prediction circuit is disconnected with the PID circuit, the microprocessor adjusts a digital potentiometer in the PID circuit according to the feedback error signal, automatic adjustment of relevant parameters of the PID circuit is achieved, and the output response time parameter tau of the gradient power amplifier under optimal PID control is obtained;
s2: the microprocessor opens K1 and closes K2, connects the rapid prediction circuit with the PID circuit in series, calculates the resistance value of the digital potentiometer in the rapid prediction circuit according to the output response time parameter tau of the gradient power amplifier, and adjusts the digital potentiometer parameters in the second-stage amplification circuit and the third-stage differential circuit of the rapid prediction circuit to make the prediction time constant in the rapid prediction circuit match with the output response time parameter tau of the gradient power amplifier, thereby realizing the rapid prediction output of the feedback error signal;
s3: the potentiometer is adjusted in a manual mode, and after passing through the ADC, the microprocessor can sense manual parameter setting in real time, so that the digital potentiometer in the PID and fast prediction circuit is controlled, and manual intervention of the output control parameters of the gradient power amplifier is realized.
Optionally, the S1 specifically includes:
s11: the microprocessor is based on the set value V SET Calculating DC bus voltage V DC The relational expression between the two is as follows:
Figure BDA0003027382720000021
k in formula (1) CONVERT Is a conversion factor between a set value and an output current, R coil Taking load resistance as well as duty ratio as D, and taking 60 percent;
according to the output current, the microprocessor outputs signals to an output voltage adjusting end of the programmable direct current power supply through the DAC and the amplifier to dynamically adjust the direct current bus voltage to a desired value V DC ；
S12: the microprocessor is based on the feedback error signal V ERROR Automatically adjusting the digital potentiometer of the PID circuit to change the proportionality coefficient K in the PID circuit in real time p Integral coefficient K i Differential coefficient K d ；
PID circuit output V OUT And V ERROR The relational expression is:
Figure BDA0003027382720000031
s13: PID circuit output V OUT Comparing with four paths of sawtooth waves with 90-degree phase shift, generating four paths of PWM waves with 90-degree phase shift, sending the four paths of PWM waves into an FPGA (field programmable gate array), generating eight paths of PWM waves with complementary dead zones after processing, sending the eight paths of PWM waves into a four-bridge arm driving circuit, controlling the output current of a gradient power amplifier by adjusting the PWM duty ratio, and controlling the gating of an H-bridge circuit switch by the FPGA by judging the positive and negative polarities of a set value signal so as to realize the direction control of the output current;
s14: and debugging and setting according to the rise-fall time, overshoot and oscillation time of the output current under different PID control parameters to obtain an output response time parameter tau during the optimal PID control of the system.
Optionally, in S2, the obtaining of the system control parameter matched with the system according to the calculation of the system parameter specifically includes:
s21: the output current response time parameter tau of the gradient power amplifier is equivalent to an RC charging signal with first-order exponential rate change, wherein tau = R 1 C 1 ；
Figure BDA0003027382720000032
V in formula (3) 0 Is a V ERROR Initial voltage of V F To stabilize the voltage, V 1 Is output from the first stage of the amplifying circuit, V T1 For the input of the first stage operational amplifier, V T2 Outputting for the first-stage operational amplifier;
s22: the feedback error signal is sent to a second-stage amplifying circuit after passing through a first-stage voltage following circuit, wherein the amplification factor of the second-stage amplifying circuit is controlled by a microprocessor through adjusting a digital potentiometer dcp1,
Figure BDA0003027382720000033
obtain the output V of the second stage amplifying circuit 2 Comprises the following steps:
Figure BDA0003027382720000034
r in the formula (5) dcp1 Is the resistance value of a digital potentiometer dcp1, R 3 Is the resistance value of the inverted input end resistor;
s23: after the signal passes through a third stage of differential circuit, the following results are obtained:
Figure BDA0003027382720000035
adjusting the resistance R of the digital potentiometer dcp2 in a differential circuit dcp2 Make a differential circuitIs consistent with the equivalent feedback error signal, so R dcp2 C 2 ＝R 1 C 1 ；
Third stage differential circuit output V 3 Comprises the following steps:
Figure BDA0003027382720000036
s24: the output V of the third stage differential circuit 3 And the output V of the first stage amplifying circuit 1 After being added, the added signals are sent to a non-inverting input end V of a fourth-stage amplifying circuit IN4+ As shown in the following formula:
Figure BDA0003027382720000041
r in the formula (8) 8 、R 11 The resistance of the resistor of the addition circuit satisfies 2R 8 ＝R 11 ；
Adjusting the resistance value of the digital potentiometer dcp1 to satisfy R dcp1 ＝R 3 Obtaining:
Figure BDA0003027382720000042
and finally amplifying the operational amplifier to obtain:
Figure BDA0003027382720000043
v in formula (10) out For fast prediction of circuit output, R 9 、R 10 The resistance value of the resistor of the amplifying circuit is satisfied with 2R 9 ＝R 10 ；
Obtaining:
V out ＝V F (11)
the fast prediction circuit can realize fast prediction output of the output current feedback signal;
s25: the microprocessor opens K1 and closes K2 through the selection switch, so that the rapid prediction circuit and the PID circuit are cascaded, the output of the rapid prediction circuit is directly sent to the PID circuit, and the response speed of the output control of the gradient power amplifier is improved.
Optionally, the S3 specifically includes:
s31: the adjustable potentiometer is adjusted in a manual mode, the microprocessor can sense manual parameter settings in a PID and rapid prediction circuit in real time through an ADC (analog to digital converter), and calculates corresponding digital potentiometer contact position parameters;
s32: the microprocessor controls the PID and the digital potentiometer contact in the quick prediction circuit to the corresponding position, thereby realizing the manual intervention and adjustment of the output current control parameter of the gradient power amplifier.
The invention has the beneficial effects that: the microprocessor is connected with the control circuit through the selection switch to adjust the quick prediction circuit, the quick prediction circuit and the PID circuit are cascaded on the basis of achieving optimal PID control, the microprocessor adjusts the resistance values of digital potentiometers of a second-stage amplifying circuit and a third-stage differential circuit in the quick prediction circuit according to the obtained system control parameters, so that the quick prediction circuit parameters are matched with the system parameters, the quick prediction of the control parameters in the control process is realized, the control effect of the control system is improved, and the application scene of the designed method is greatly widened; based on dynamic parameter adjustment realized by an adjustable potentiometer, an ADC (analog to digital converter), a microprocessor and a digital potentiometer, manual intervention and adjustment of the gradient power amplifier under different application scenes are realized by manually adjusting parameters of a rapid prediction circuit, and the control effect of output current is adjusted in real time.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic block diagram of a portion of a fast prediction circuit;
FIG. 2 is a diagram of the overall scheme of the fast predictive control circuit;
fig. 3 is an overall block diagram of the hardware system of the adaptive fast predictive control gradient power amplifier.
Detailed Description
The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
FIG. 1 is a schematic block diagram of a portion of a fast prediction circuit; FIG. 2 is a diagram of an overall scheme of a fast predictive control circuit; fig. 3 is an overall block diagram of the hardware system of the adaptive fast predictive control gradient power amplifier. A gradient power amplifier device based on self-adaptive fast predictive control is composed of a four-leg power circuit and a fast feedback predictive circuit, wherein the four-leg power circuit comprises a four-leg driving circuit, a four-leg switching circuit, an LC filter circuit and a current positive and negative phase switching H-bridge circuit which are sequentially connected; the rapid feedback prediction circuit comprises an amplifier, a rapid prediction circuit, a PID circuit and a comparator which are realized by an analog circuit, a microprocessor, an FPGA, a DAC converter, a digital potentiometer, an adjustable potentiometer and an ADC converter which are connected in sequence, and the rapid prediction circuit comprises a first-stage following circuit, a second-stage amplifying circuit, a third-stage differential circuit and a fourth-stage amplifying circuit which are connected in sequence.
The invention provides a gradient power amplifier based on self-adaptive prediction control and a design method thereof, wherein the method comprises the following steps:
s1: the microprocessor closes K1 and opens K2, the rapid prediction circuit is disconnected with the PID circuit, the microprocessor adjusts a digital potentiometer in the PID circuit according to the feedback error signal, automatic adjustment of relevant parameters of the PID circuit is achieved, and the output response time parameter tau of the gradient power amplifier under optimal PID control is obtained;
s2: the microprocessor opens K1 and closes K2, connects the rapid prediction circuit with the PID circuit in series, calculates the resistance value of the digital potentiometer in the rapid prediction circuit according to the output response time parameter tau of the gradient power amplifier, and adjusts the digital potentiometer parameters in the second-stage amplification circuit and the third-stage differential circuit of the rapid prediction circuit to make the prediction time constant in the rapid prediction circuit match with the output response time parameter tau of the gradient power amplifier, thereby realizing the rapid prediction output of the feedback error signal;
s3: the potentiometer is adjusted in a manual mode, and after passing through the ADC, the microprocessor can sense manual parameter setting in real time, so that the digital potentiometer in the PID and fast prediction circuit is controlled, and manual intervention of the output control parameters of the gradient power amplifier is realized.
In step S1, the method specifically includes:
s11: the microprocessor is based on the set value V SET Calculating DC bus voltage V DC The relational expression between the two is as follows:
Figure BDA0003027382720000061
k in formula (1) CONVERT Is a conversion factor between a set value and an output current, R coil Taking load resistance as well as duty ratio as D, and taking 60 percent;
according to the output current, the microprocessor outputs signals to an output voltage adjusting end of the programmable DC power supply through the DAC and the amplifier to dynamically adjust the DC bus voltage to a desired value V DC ；
S12: the microprocessor is based on the feedback error signal V ERROR Automatically adjusting the digital potentiometer of the PID circuit to change the proportionality coefficient K in the PID circuit in real time p Integral coefficient K i Differential coefficient K d ；
PID circuit output V OUT And V ERROR The relational expression is:
Figure BDA0003027382720000062
s13: PID circuit output V OUT Comparing with four paths of sawtooth waves with 90-degree phase shift, generating four paths of PWM waves with 90-degree phase shift, sending the four paths of PWM waves into an FPGA (field programmable gate array), generating eight paths of PWM waves with complementary dead zones after processing, sending the eight paths of PWM waves into a four-bridge arm driving circuit, controlling the output current of a gradient power amplifier by adjusting the PWM duty ratio, and controlling the gating of an H-bridge circuit switch by the FPGA by judging the positive and negative polarities of a set value signal so as to realize the direction control of the output current;
s14: and debugging and setting according to the rise-fall time, overshoot and oscillation time of the output current under different PID control parameters to obtain an output response time parameter tau during the optimal PID control of the system.
In step S2, the step of calculating and obtaining the system control parameter matched with the system according to the system parameter specifically includes:
s21: the gradient power amplifier output current response time parameter tau is equivalent to an RC charging signal with first-order exponential rate change, namely tau = R 1 C 1 。
Figure BDA0003027382720000071
V in formula (3) 0 Is a V ERROR Initial voltage of V F To stabilize the voltage, V 1 Is output from the first stage of the amplifying circuit, V T1 For the first stage operational amplifier input, V T2 Outputting for the first-stage operational amplifier;
s22: the feedback error signal is sent to a second-stage amplifying circuit after passing through a first-stage voltage following circuit, wherein the amplification factor of the second-stage amplifying circuit is controlled by a microprocessor through adjusting a digital potentiometer dcp1,
Figure BDA0003027382720000072
to obtain the output V of the second-stage amplifying circuit 2 Comprises the following steps:
Figure BDA0003027382720000073
r in the formula (5) dcp1 Is the resistance value of a digital potentiometer dcp1, R 3 Is the resistance value of the inverted input end resistor;
s23: after the signal passes through a third stage of differential circuit, the following can be obtained:
Figure BDA0003027382720000074
adjusting a differential circuitResistance R of middle digital potentiometer dcp2 dcp2 So that the time constant of the differentiating circuit is consistent with the equivalent feedback error signal, R dcp2 C 2 ＝R 1 C 1 ；
Third stage differential circuit output V 3 Comprises the following steps:
Figure BDA0003027382720000075
s24: the output V of the third stage differential circuit 3 And the output V of the first stage amplifying circuit 1 After being added, the added signals are sent to a non-inverting input end V of a fourth-stage amplifying circuit IN4+ As shown in the following formula:
Figure BDA0003027382720000076
r in the formula (8) 8 、R 11 The resistance value of the resistor of the addition circuit satisfies 2R 8 ＝R 11 ；
Adjusting the resistance value of the digital potentiometer dcp1 to satisfy R dcp1 ＝R 3 Obtaining:
Figure BDA0003027382720000077
after the amplification of the final operational amplifier, the following can be obtained:
Figure BDA0003027382720000081
v in formula (10) out For fast prediction of circuit output, R 9 、R 10 The resistance of the resistor of the amplifying circuit satisfies 2R 9 ＝R 10 ；
Obtaining the following components:
V out ＝V F (11)
namely, the fast prediction circuit can realize fast prediction output of the output current feedback signal.
S25: the microprocessor opens the K1 and closes the K2 through the selection switch, so that the rapid prediction circuit and the PID circuit are cascaded, the output of the rapid prediction circuit is directly sent to the PID circuit, and the response speed of the output control of the gradient power amplifier is improved.
In step S3, the method specifically includes:
s31: the adjustable potentiometer is adjusted in a manual mode, the microprocessor can sense manual parameter settings in a PID and rapid prediction circuit in real time through an ADC converter, and calculates corresponding digital potentiometer contact position parameters;
s32: the microprocessor controls the PID and the digital potentiometer contact in the quick prediction circuit to the corresponding position, thereby realizing the manual intervention and adjustment of the output current control parameter of the gradient power amplifier.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims (5)

1. A design method of a gradient power amplifier based on self-adaptive prediction control is characterized by comprising the following steps: the method comprises the following steps:
s1: the microprocessor closes K1 and opens K2, the rapid prediction circuit is disconnected with the PID circuit, the microprocessor adjusts a digital potentiometer in the PID circuit according to the feedback error signal, automatic adjustment of relevant parameters of the PID circuit is achieved, and the output response time parameter tau of the gradient power amplifier under optimal PID control is obtained;
s2: the microprocessor opens K1 and closes K2, connects the rapid prediction circuit with the PID circuit in series, calculates the resistance value of the digital potentiometer in the rapid prediction circuit according to the output response time parameter tau of the gradient power amplifier, and adjusts the resistance values of the digital potentiometers in the second-stage amplification circuit and the third-stage differential circuit of the rapid prediction circuit to make the prediction time constant in the rapid prediction circuit match with the output response time parameter tau of the gradient power amplifier, thereby realizing the rapid prediction output of the feedback error signal;
s3: the adjustable potentiometer is adjusted in a manual mode, and after passing through the ADC, the microprocessor can sense the parameter setting of the adjustable potentiometer in real time, so that the digital potentiometer in the PID and fast prediction circuit is controlled, and the manual intervention of the output control parameters of the gradient power amplifier is realized.
2. The method for designing a gradient power amplifier based on adaptive prediction control according to claim 1, wherein the method comprises the following steps: the S1 specifically comprises:
s11: the microprocessor is based on the set value V SET Calculating DC bus voltage V DC The relational expression between the two is as follows:
Figure FDA0003882642020000011
k in formula (1) CONVERT Is a conversion factor between a set value and an output current, R coil Taking load resistance as well as duty ratio as D, and taking 60 percent;
according to the output current, the microprocessor outputs signals to an output voltage adjusting end of the programmable direct current power supply through the DAC and the amplifier to dynamically adjust the direct current bus voltage to a desired value V DC ；
S12: the microprocessor is based on the feedback error signal V ERROR Automatically adjusting the digital potentiometer of the PID circuit to change the proportionality coefficient K in the PID circuit in real time p Integral coefficient K i Differential coefficient K d ；
PID circuit output V OUT And V ERROR The relational expression is:
Figure FDA0003882642020000012
s13: PID electricityOutput V OUT Comparing with four paths of sawtooth waves with 90-degree phase shift, generating four paths of PWM waves with 90-degree phase shift, sending the four paths of PWM waves into an FPGA (field programmable gate array), generating eight paths of PWM waves with complementary dead zones after processing, sending the eight paths of PWM waves into a four-bridge arm driving circuit, controlling the output current of a gradient power amplifier by adjusting the PWM duty ratio, and controlling the gating of an H-bridge circuit switch by the FPGA by judging the positive and negative polarities of a set value signal so as to realize the direction control of the output current;
s14: and debugging and setting according to the rise-fall time, overshoot and oscillation time of the output current under different PID control parameters to obtain an output response time parameter tau during the optimal PID control of the system.
3. The method for designing a gradient power amplifier based on adaptive prediction control according to claim 1, wherein the method comprises the following steps: in S2, the obtaining of the system control parameter matched with the system according to the system parameter calculation specifically includes:
s21: the gradient power amplifier output current response time parameter tau is equivalent to an RC charging signal with first-order exponential rate change, namely tau = R 1 C 1 ；
Figure FDA0003882642020000021
V in formula (3) 0 Is a V ERROR Initial voltage of V F To stabilize the voltage, V 1 Is the output of the first stage of amplification circuit, V T1 For the input of the first stage operational amplifier, V T2 Outputting for the first-stage operational amplifier;
s22: the feedback error signal is fed into the second stage amplifier circuit after passing through the first stage voltage follower circuit, wherein the amplification factor of the second stage amplifier circuit is controlled by the microprocessor through adjusting the digital potentiometer dcp1
Figure FDA0003882642020000022
Obtain the output of the second stage amplifying circuitV 2 Comprises the following steps:
Figure FDA0003882642020000023
r in the formula (5) dcp1 Is the resistance value of a digital potentiometer dcp1, R 3 Is the resistance value of the inverted input end resistor;
s23: after the signal passes through a third stage of differential circuit, the following results are obtained:
Figure FDA0003882642020000024
adjusting the resistance R of a digital potentiometer dcp2 in a differential circuit dcp2 The time constant of the differentiating circuit is made to coincide with the equivalent feedback error signal, so R dcp2 C 2 ＝τ＝R 1 C 1 ；
Third stage differential circuit output V 3 Comprises the following steps:
Figure FDA0003882642020000025
s24: the third stage differential circuit output V 3 And the output V of the first stage amplifying circuit 1 After being added, the added signals are sent to a non-inverting input end V of a fourth-stage amplifying circuit IN4+ As shown in the following formula:
Figure FDA0003882642020000026
r in the formula (8) 8 、R 11 The resistance of the resistor of the addition circuit satisfies 2R 8 ＝R 11 ；
Adjusting the resistance value of the digital potentiometer dcp1 to satisfy R dcp1 ＝R 3 Obtaining:
Figure FDA0003882642020000031
and finally amplifying the operational amplifier to obtain:
Figure FDA0003882642020000032
v in formula (10) out For fast prediction of circuit output, R 9 、R 10 The resistance value of the resistor of the amplifying circuit is satisfied with 2R 9 ＝R 10 ；
Obtaining:
V out ＝V F (11)
the fast prediction circuit can realize fast prediction output of the output current feedback signal;
s25: the microprocessor opens the K1 and closes the K2 through the selection switch, so that the rapid prediction circuit and the PID circuit are cascaded, the output of the rapid prediction circuit is directly sent to the PID circuit, and the response speed of the output control of the gradient power amplifier is improved.
4. The method for designing a gradient power amplifier based on adaptive prediction control according to claim 1, wherein the method comprises the following steps: the S3 specifically includes:
s31: the adjustable potentiometer is adjusted in a manual mode, the microprocessor can sense manual parameter settings in a PID and rapid prediction circuit in real time through an ADC (analog to digital converter), and calculates corresponding digital potentiometer contact position parameters;
s32: the microprocessor controls the PID and the digital potentiometer contact in the quick prediction circuit to the corresponding position, thereby realizing the manual intervention and adjustment of the output current control parameter of the gradient power amplifier.
5. A gradient power amplifier designed according to the method of claim 2, wherein: the system comprises a four-bridge arm power circuit and a rapid feedback prediction circuit which are sequentially connected;
the four-leg power circuit comprises a four-leg driving circuit, a four-leg switching circuit, an LC filter circuit and a current positive and negative phase switching H-bridge circuit which are sequentially connected;
the rapid feedback prediction circuit comprises an amplifier, a rapid prediction circuit, a PID circuit, a comparator, a microprocessor, an FPGA, a DAC converter, a digital potentiometer, an adjustable potentiometer and an ADC which are realized by an analog circuit which are connected in sequence;
the microprocessor adjusts the fast prediction circuit to access the control circuit through the selection switch, the fast prediction circuit and the PID circuit are cascaded on the basis of achieving the optimal PID control, and the microprocessor adjusts the resistance values of the digital potentiometers of the second-stage amplification circuit and the third-stage differential circuit in the fast prediction circuit according to the obtained system control parameters, so that the fast prediction circuit parameters are matched with the system parameters, and fast prediction of the control parameters in the control process is realized.
CN202110419600.1A 2021-04-19 2021-04-19 Gradient power amplifier based on self-adaptive prediction control and design method thereof Active CN113114136B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110419600.1A CN113114136B (en) 2021-04-19 2021-04-19 Gradient power amplifier based on self-adaptive prediction control and design method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110419600.1A CN113114136B (en) 2021-04-19 2021-04-19 Gradient power amplifier based on self-adaptive prediction control and design method thereof

Publications (2)

Publication Number Publication Date
CN113114136A CN113114136A (en) 2021-07-13
CN113114136B true CN113114136B (en) 2022-11-25

Family

ID=76718775

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110419600.1A Active CN113114136B (en) 2021-04-19 2021-04-19 Gradient power amplifier based on self-adaptive prediction control and design method thereof

Country Status (1)

Country Link
CN (1) CN113114136B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114545996B (en) * 2022-03-10 2022-12-27 中国科学院半导体研究所 Temperature control circuit of semiconductor laser

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10201273A (en) * 1997-01-10 1998-07-31 Denso Corp Method and device for measuring steady-state deviation of pid control circuit
CN110995181A (en) * 2019-12-31 2020-04-10 南京磁晨医疗技术有限公司 Gradient power amplifier

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6724191B1 (en) * 2000-05-09 2004-04-20 Admiralty Corporation Systems and methods useful for detecting presence and/or location of various materials
EP1595159A1 (en) * 2003-02-03 2005-11-16 Koninklijke Philips Electronics N.V. Precision gradient amplifier with multiple output voltage levels
US9541609B2 (en) * 2008-07-11 2017-01-10 Koninklijke Philips Electronics N.V. Digital amplifier with feedforward and feedback control
CN102508183B (en) * 2011-11-11 2013-09-11 辽宁开普医疗***有限公司 Digital variable frequency PWM (Pulse Width Modulation) gradient amplifier with adaptively-controlled load
CN102857184B (en) * 2012-09-28 2015-03-04 电子科技大学 Gradient amplifier control device
CN104950273A (en) * 2014-03-28 2015-09-30 辽宁开普医疗***有限公司 Gradient amplifier applying coupled inductors to output filter
CA2982449A1 (en) * 2015-04-13 2016-10-20 Hyperfine Research, Inc. Magnetic coil power methods and apparatus
NL2015303B1 (en) * 2015-08-13 2017-02-28 Prodrive Tech Bv Electric power converter and MRI system comprising such converter.
WO2018027893A1 (en) * 2016-08-12 2018-02-15 上海联影医疗科技有限公司 Gradient power amplifier debugging method and system
CN111478610A (en) * 2020-04-09 2020-07-31 湖南盈晟电子科技有限公司 Phase-shifting frequency-doubling switch power amplifier

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10201273A (en) * 1997-01-10 1998-07-31 Denso Corp Method and device for measuring steady-state deviation of pid control circuit
CN110995181A (en) * 2019-12-31 2020-04-10 南京磁晨医疗技术有限公司 Gradient power amplifier

Also Published As

Publication number Publication date
CN113114136A (en) 2021-07-13

Similar Documents

Publication Publication Date Title
CN113114136B (en) Gradient power amplifier based on self-adaptive prediction control and design method thereof
WO2020220558A1 (en) Digital control method for achieving multi-step frequency modulation of llc resonant converter
CN115441850B (en) Impedance matching method and device of radio frequency power supply system and power supply system
WO2009009984A1 (en) A power supply adjusting unit
CN109541935B (en) Parameter adaptive fractional order active disturbance rejection automatic power generation control method
CN102223077B (en) Sliding-mode controller of LLC (logic link control) series resonance DC-DC converter and control method thereof
CN102355131B (en) Hybrid control method and device of four-switch Buck-Boost converter
CN109004827B (en) Control system for self-adaptive asymmetric dead time of cascade converter
CN108258900B (en) DC-DC converter and power modulator
CN113364291A (en) Two-mode control method and system for bidirectional reversible direct current converter
CN203275625U (en) High-voltage heavy-current small-ripple gradient amplifier
CN111245238A (en) Three-level Boost circuit control method and system
CN111245203A (en) High-performance storage ring magnet power supply
CN104142483A (en) High-voltage high-current small-ripple-wave gradient amplifier
CN114362544B (en) Topological structure of charge control LLC resonant converter and load feedforward method thereof
CN109521833B (en) Broadband signal conditioning device for arbitrary waveform generator
CN113098523B (en) Digital delta-sigma and PID based double-loop control method and high-precision alternating current source
CN108233875B (en) Radio frequency amplifier, method for improving efficiency of radio frequency amplifier and radio frequency power supply
CN101136616B (en) Sigma-Delta type power amplifier and modulation method thereof
CN113765354B (en) Soft start method for LLC resonant converter linear compensation
CN112865533B (en) Flying capacitor voltage balance circuit of three-level step-down DC-DC converter
CN113078834B (en) Inverter based on digital delta-sigma and PID double-loop control and design method
CN202043080U (en) Broadband direct current amplification device
CN111555646B (en) High-bandwidth linear amplification circuit of switching power supply and control method thereof
JPH05275946A (en) Gain control amplifier

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant