Current type DC / DC current-rising chopper circuit construction and simulation correction method

Abstract

The invention discloses a current type DC / DC current-rising chopper circuit construction and simulation correction method, and the method comprises the steps: S1, constructing a current type DC / DC current-rising chopper circuit, and determining the parameters of all components in the circuit; s2, simulating the working mode of the current type DC / DC current-rising chopper circuit based on the constructed current type DC / DC current-rising chopper circuit; s3, carrying out modeling analysis on the constructed current type DC / DC current rising chopper circuit through a small signal analysis method; and S4, constructing a closed loop of the current type DC / DC current-rising chopper circuit, and correcting the current type DC / DC current-rising chopper circuit. A DC-DC current-rising chopping conversion circuit construction and simulation correction method is designed, the working principle and the potential application environment of the DC-DC current-rising chopping conversion circuit are systematically elaborated in detail, and a specific equivalent model is constructed to perform detailed and detailed analysis on different working states of the DC-DC current-rising chopping conversion circuit; a closed-loop regulator is established for a current rising circuit, and stability analysis is carried out by using a root locus and Bode so that the conditions that the amplitude margin is 45 degrees and the system bandwidth is 200Hz are met.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and more particularly to a current type DC / DC current boost chopper circuit construction and simulation correction method. Background Art

[0002] According to the current situation analysis, power electronics technology has become one of the important basic technologies in my country's national economy, and its development can also drive the improvement of the quality of the power system. In recent years, with the rapid development of my country's economy, it has provided sufficient material guarantees for the development of many industries, especially the application of electronic power technology has also shown a good momentum of rapid development. In the face of the current global energy crisis and environmental pollution problems, power electronics technology has also played a huge role in the field of electrical engineering with its own characteristics. Modern power electronics technology is becoming more and more mature, and power electronic circuits are already quite complete for the realization of power conversion such as AC-DC, DC-DC, DC-AC, AC-AC, etc., and can adapt to different occasions.

[0003] Chopper circuit is an important part of modern power electronics technology and is widely used in voltage regulation and conversion of DC power supply. It is usually composed of fully controlled power electronic devices (such as MOSFET, IGBT, etc.), diodes, inductors and capacitors. According to whether it is isolated by a transformer, DC / DC conversion circuits can be divided into two categories: isolated and non-isolated. The isolated circuit provides electrical isolation between the input and output through a transformer. Common topologies include flyback, forward, half-bridge and full-bridge. It is suitable for application scenarios that require input and output isolation, such as communication equipment and electric vehicle chargers. The non-isolated circuit has no transformer isolation and directly realizes voltage conversion through electronic components. It has a simple structure, high efficiency and low cost. It is widely used in portable electronic devices and battery management systems.

[0004] According to the different circuit wiring forms and functions, non-isolated circuits can be divided into buck, boost, buck-boost, Cuk, Sepic and Zeta circuits. Buck circuit reduces the higher DC voltage to a lower voltage, which is suitable for voltage-stabilized power supplies and chargers; Boost circuit increases the lower voltage to a higher voltage, which is often used in photovoltaic power generation systems and electric vehicles; Buck-Boost circuit can adjust the voltage when the input voltage is higher or lower than the output voltage, which is suitable for occasions where the input voltage fluctuates greatly; Cuk circuit realizes voltage up and down conversion through dual conversion of inductance and capacitance, which is suitable for applications sensitive to current fluctuations; SEPIC circuit maintains a stable voltage when the input voltage is higher or lower than the output voltage, which is suitable for systems with a wide input voltage range; Zeta circuit achieves stable output through a combination of two sets of inductors and capacitors, providing better efficiency and stability in some applications. Different types of DC / DC conversion circuits have their own advantages and disadvantages in practical applications. Non-isolated circuits have simple structures, low costs, and high efficiency, which are suitable for portable devices and LED drivers, but are not suitable for application scenarios with high safety requirements; isolated circuits provide electrical isolation to ensure safety and interference suppression, and are widely used in industry, power and communications. Choosing the right type of DC / DC converter circuit requires comprehensive consideration based on specific application requirements, input and output voltage range, power level, safety requirements, etc. With the development of technology, DC / DC converter circuits are constantly improving in terms of energy efficiency, stability, and integration, and will play an important role in more fields.

[0005] The publication number is CN105048807A, and the name is a boost chopper circuit and its current sharing control method. It specifically discloses that a current sharing current comparison circuit is used to receive a current sharing signal and a current feedback signal of a BOOST main circuit to output a first error signal, and then the superposition signal composed of the first error signal and a given voltage signal and the voltage feedback signal of the BOOST main circuit are connected to the voltage comparison circuit to obtain a second error signal, thereby changing the duty cycle of the PWM controller output drive square wave, and controlling the opening and closing of the power tube through the drive circuit to achieve output tracking and set, so as to achieve the purpose of adjustable voltage and parallel current sharing, solve the problem that the output voltage of the existing boost chopper circuit is fixed and cannot be adjusted and cannot work in parallel, and realizes that it can be used for parallel current sharing to increase the module capacity.

[0006] The publication number is CN109462333A, and the name is a continuous input current active switch capacitor Z source boost chopper circuit, which specifically discloses a DC input power supply Vin, a first inductor (L) 1, a second inductor (L2), a first capacitor (C1), a second capacitor (C2), a third capacitor (C3), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D) 4, a first switch tube (S1), a second switch tube (S2), an output capacitor (Cout) and a load. Compared with a Boost converter, a traditional quasi-Z source converter, etc., the present invention has a higher voltage gain and lower capacitor, switch and diode voltage stress, and the input current is continuous, and is suitable for non-isolated high-gain DC voltage conversion occasions.

[0007] Therefore, how to provide a fast-response and highly stable current-type DC / DC boost chopper circuit construction and simulation correction method is a problem that those skilled in the art need to solve urgently. Summary of the invention

[0008] In view of this, the present invention provides a current-type DC / DC current boost chopper circuit construction and simulation correction method, aiming to solve the above technical problems.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A current-type DC / DC current boost chopper circuit construction and simulation correction method, comprising:

[0011] Step S1, constructing a current-type DC / DC current-boosting chopper circuit, and determining the parameters of each component in the circuit;

[0012] Step S2, based on the constructed current-type DC / DC current-boosting chopper circuit, simulating its working mode;

[0013] Step S3, modeling and analyzing the constructed current-source DC / DC current-boosting chopper circuit by a small signal analysis method;

[0014] Step S4: construct a closed loop of the current-source DC / DC current-boosting chopper circuit, and calibrate the current-source DC / DC current-boosting chopper circuit.

[0015] Furthermore, the construction of the current-type DC / DC current boost chopper circuit described in step S1 is specifically as follows:

[0016] The current-type DC / DC current-boosting chopper circuit includes a DC power supply with a constant output, a fully controlled switching device IGBT or MOSFET controlled by a PWM signal, and also includes energy storage elements such as a capacitor C and an inductor L, a diode VD, and a load resistor R;

[0017] When the trigger pulse is not loaded, the IGBT is turned off, and the constant current source will be used to charge the energy storage capacitor C. After a period of time t off After that, the pulse generator outputs a positive pulse, and the IGBT is turned on. At this time, the current released by the constant current source and the capacitor C passes through the inductor together to supply power to the resistor R. The current in the inductor L gradually increases, and the voltage difference between the input and output terminals is converted into electromagnetic energy and stored. After t on After a certain time, the IGBT is turned off again, and the constant current source continues to charge the capacitor C. The current in the inductor L cannot change suddenly, and the self-induced electromotive force will be generated in the inductor to hinder the decrease of the current. At this time, the diode is forward-conducted, and the current in the circuit decreases slowly. The magnetic energy stored in the circuit is converted into electrical energy and released to the load. After a certain time t off Repeat the above process until the entire circuit reaches a stable state.

[0018] Furthermore, the parameters of each component in the determining circuit are specifically:

[0019] When the IGBT is turned on, the voltage across the inductor is V i -V o , the inductor converts electrical energy into magnetic energy and stores it, and the current increases by ΔI L1 for:

[0020]

[0021] Where L is the inductance, V L is the inductor voltage, V i is the voltage at the inductor input terminal, V o The voltage at the inductor output terminal is:

[0022] When the IGBT is turned off, the magnetic field energy stored in the inductor is converted into electric field energy and released, and the current decreases by ΔI L2 for:

[0023]

[0024] Because when the circuit is stable, the above two currents are equal, then:

[0025]

[0026] Assuming the circuit is lossless and the input and output powers are the same, then:

[0027] I i V i =I o V o

[0028] but

[0029]

[0030] Will Substituting into the above formula, we can get:

[0031]

[0032] Among them, the average value of the entire current input is I i , the average output current is I o , D is the duty cycle of the control pulse;

[0033] The filter inductance value is calculated based on the ripple coefficient requirement for the output current. The relationship between the output current ripple peak and the inductance is shown in the following formula:

[0034]

[0035] Furthermore, based on the constructed current-type DC / DC current boost chopper circuit, its working mode is simulated, and the working mode includes a capacitor voltage continuous working mode and a capacitor voltage discontinuous working mode.

[0036] Furthermore, the capacitor voltage continuous working mode is specifically:

[0037] When the capacitor voltage is in a continuous state, it goes through two working states, on and off, in one working cycle of the circuit. The on state of the circuit switch is represented by 0 and 1, and the average value of the entire current input is I i and the average output current is I o ;

[0038] When the switch is set to zero, that is, the circuit switch is turned off, the constant current source charges the capacitor, and the capacitor voltage increases linearly. The load resistor on the other side forms a closed loop with the diode through the freewheeling effect of the inductor, the inductor discharges, and the current in the load decreases;

[0039] When the switch is in state 1 and the entire circuit is in state 1, the constant current source and the capacitor charge the load together, the capacitor voltage decreases, the capacitor discharges, the capacitor current direction is reversed, the capacitor current and the constant current source current flow through the switch tube together, and the load current increases;

[0040] When the capacitance is relatively large, the capacitance voltage is continuous, so I s =D·I l , I s is the current of the current source, I l is the current in the load, D is the duty cycle, if the capacitor voltage remains continuous, the initial and final voltages remain consistent, when it is turned off, the power supply charges the capacitor; when it is turned on, the capacitor discharges itself, and the voltage drop during discharge should be equal to the voltage increase during charging, which is as follows:

[0041] I s ·toff =(I l -I s )·t on

[0042] Then the relationship between the output current and the input current is:

[0043]

[0044] Furthermore, the capacitor voltage intermittent working mode is specifically:

[0045] When the capacitor is very small, the capacitor voltage will be zero during the entire discharge process, and the capacitor voltage will be intermittent. When the capacitor voltage is intermittent, the entire current boost circuit has three working modes. According to the critical condition of the capacitor voltage continuity and the law of conservation of energy, the following formula is obtained:

[0046]

[0047] The current equation is as follows:

[0048]

[0049] The boundary conditions for voltage continuity are as follows:

[0050]

[0051]

[0052] Furthermore, the modeling analysis of the constructed current-type DC / DC boost chopper circuit by the small signal analysis method described in step S3 is specifically as follows:

[0053] Assume that IGBT and diode are ideal switches, filter inductor L is an ideal inductor, the circuit works in continuous current mode, and the load resistance is R;

[0054] When the IGBT is turned on, the state equation is:

[0055]

[0056]

[0057] When the IGBT is turned off, the diode D 1 The freewheeling conduction is on, and the state is:

[0058]

[0059]

[0060] Therefore, the average state equation of the capacitor and inductor in one cycle is:

[0061]

[0062]

[0063] In steady state, Then i s (t) = D·i L (t), U c (t)·D=i L ·R, the output current is a constant, and its magnitude is proportional to the inverse of the input current and the duty cycle.

[0064] Furthermore, it also includes:

[0065] The state variables of the circuit fluctuate around the steady-state value, so:

[0066]

[0067] Omitting the product of the two fluctuations, we can obtain:

[0068]

[0069] The steady-state value plus the small signal fluctuation value gives:

[0070]

[0071] Omitting the product of the two fluctuations yields:

[0072]

[0073] The input current is constant within the switching frequency band. Performing Laplace transform yields:

[0074]

[0075] but

[0076]

[0077]

[0078] eliminate get:

[0079]

[0080] That is, the control-output small signal transfer function of this converter circuit when the inductor current and capacitor voltage are continuous, then the original loop gain function G 0 As shown below:

[0081]

[0082] Among them, G vd (s) is the transfer function of the low-pass filter, V m is the peak-to-peak value of the carrier signal.

[0083] Furthermore, the step S4 is specifically as follows:

[0084] Based on the basic principle of closed-loop control circuit, the influence of relevant parameters on the closed-loop control link is analyzed to determine the PI parameters. The output current is sampled and compared with the current reference value to obtain the error value. The error value is amplified by the PI controller. The output value is compensated and intersected with the triangular carrier, that is, the modulation wave to control the duty cycle, and then control the on and off of the switching device IGBT, so that its output current is controlled to be accurate to the reference current value.

[0085] Furthermore, the circuit is specifically:

[0086] A current source, a capacitor connected in series with the current source, a switch S and a diode VD connected in parallel with the capacitor, and an inductor L and a resistor R connected in parallel with the diode VD.

[0087] The above technical solution includes at least the following technical effects:

[0088] Through the above technical solutions, it can be known that the present invention discloses a current-type DC / DC current boost chopper circuit construction and simulation correction method. Compared with the prior art, the present invention derives and designs a DC-DC current boost chopper conversion circuit by analogy with the step-down chopper circuit, and systematically and in detail explains its working principle and its potential application environment, and constructs a specific equivalent model to conduct a detailed and detailed analysis of its different working states; a closed-loop regulator is established for the current boost circuit, and stability analysis is performed using root loci and Burdett to make it meet the conditions of an amplitude margin of 45 degrees and a system bandwidth of 200Hz. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0090] Figure 1 The present invention is a schematic structural diagram of a current-boosting chopper conversion circuit.

[0091] Figure 2 A DT of the present invention S Schematic diagram of the structure of the state diagram.

[0092] Figure 3 A 1-DT S Schematic diagram of the structure.

[0093] Figure 4 It is a structural schematic diagram of a capacitor voltage continuous working mode of the present invention.

[0094] Figure 5 It is a structural schematic diagram of a capacitor voltage discontinuous working mode of the present invention.

[0095] Figure 6 The figure is a schematic diagram of the structure of a main circuit of the present invention.

[0096] Figure 7 The figure is a structural schematic diagram of a main circuit output waveform of the present invention.

[0097] Figure 8 The figure is a schematic diagram of the structure of a closed-loop circuit equivalent control of the present invention.

[0098] Fig. 9 The figure is a schematic diagram of the structure of a step current output waveform of the present invention.

[0099] Fig.10 The figure is a schematic structural diagram of a closed-loop transfer function root locus of the present invention. DETAILED DESCRIPTION

[0100] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0101] See attached Figure 1-10 The embodiment of the present invention discloses a current-type DC / DC current boost chopper circuit construction and simulation correction method, including:

[0102] Step S1, constructing a current-type DC / DC current-boosting chopper circuit, and determining the parameters of each component in the circuit;

[0103] Step S2, based on the constructed current-type DC / DC current-boosting chopper circuit, simulating its working mode;

[0104] Step S3, modeling and analyzing the constructed current-source DC / DC current-boosting chopper circuit by a small signal analysis method;

[0105] Step S4: construct a closed loop of the current-source DC / DC current-boosting chopper circuit, and calibrate the current-source DC / DC current-boosting chopper circuit.

[0106] To further optimize the above technical solution, the construction of the current-type DC / DC current-boosting chopper circuit in step S1 is specifically as follows:

[0107] The current-type DC / DC boost chopper circuit includes a DC power supply with a constant output, a fully controlled switching device IGBT or MOSFET controlled by a PWM signal, and also includes energy storage elements capacitor C and inductor L, a diode VD, and a load resistor R;

[0108] When the trigger pulse is not loaded, the IGBT is turned off, and the constant current source will be used to charge the energy storage capacitor C. After a period of time t off After that, the pulse generator outputs a positive pulse, and the IGBT is turned on. At this time, the current released by the constant current source and the capacitor C passes through the inductor together to supply power to the resistor R. The current in the inductor L gradually increases, and the voltage difference between the input and output terminals is converted into electromagnetic energy and stored. After t on After a certain time, the IGBT is turned off again, and the constant current source continues to charge the capacitor C. The current in the inductor L cannot change suddenly, and the self-induced electromotive force will be generated in the inductor to hinder the decrease of the current. At this time, the diode is forward-conducted, and the current in the circuit decreases slowly. The magnetic energy stored in the circuit is converted into electrical energy and released to the load. After a certain time t off Repeat the above process until the entire circuit reaches a stable state.

[0109] In order to further optimize the above technical solution, the parameters of each component in the circuit are determined as follows:

[0110] When the IGBT is turned on, the voltage across the inductor is V i -V o , the inductor converts electrical energy into magnetic energy and stores it, and the current increases by ΔI L1 for:

[0111]

[0112] Where L is the inductance, V L is the inductor voltage, V i is the voltage at the inductor input terminal, V o The voltage at the inductor output terminal is:

[0113] When the IGBT is turned off, the magnetic field energy stored in the inductor is converted into electric field energy and released, and the current decreases by ΔI L2 for:

[0114]

[0115] Because when the circuit is stable, the above two currents are equal, then:

[0116]

[0117] Assuming the circuit is lossless and the input and output powers are the same, then:

[0118] I i V i =I o V o

[0119] but

[0120]

[0121] Will Substituting into the above formula, we can get:

[0122]

[0123] Among them, the average value of the entire current input is I i , the average output current is I o , D is the duty cycle of the control pulse:

[0124] The filter inductance value is calculated based on the ripple coefficient requirement for the output current. The relationship between the output current ripple peak and the inductance is shown in the following formula:

[0125]

[0126] In order to further optimize the above technical solution, based on the constructed current-type DC / DC current boost chopper circuit, its working mode is simulated, and the working modes include capacitor voltage continuous working mode and capacitor voltage intermittent working mode.

[0127] In order to further optimize the above technical solution, the capacitor voltage continuous working mode is specifically as follows:

[0128] When the capacitor voltage is in a continuous state, it goes through two working states, on and off, in one working cycle of the circuit. The on state of the circuit switch is represented by 0 and 1, and the average value of the entire current input is I i and the average output current is I o ;

[0129] When the switch is set to zero, that is, the circuit switch is turned off, the constant current source charges the capacitor, and the capacitor voltage increases linearly. The load resistor on the other side forms a closed loop with the diode through the freewheeling effect of the inductor, the inductor discharges, and the current in the load decreases;

[0130] When the switch is in state 1 and the entire circuit is in state 1, the constant current source and the capacitor charge the load together, the capacitor voltage decreases, the capacitor discharges, the capacitor current direction is reversed, the capacitor current and the constant current source current flow through the switch tube together, and the load current increases;

[0131] When the capacitance is relatively large, the capacitance voltage is continuous, so I s=D·I l , I s is the current of the current source, I l is the current in the load, D is the duty cycle, if the capacitor voltage remains continuous, the initial and final voltages remain consistent, when it is turned off, the power supply charges the capacitor; when it is turned on, the capacitor discharges itself, and the voltage drop during discharge should be equal to the voltage increase during charging, which is as follows:

[0132] I s ·t off =(I l -I s )·t on

[0133] Then the relationship between the output current and the input current is:

[0134]

[0135] In order to further optimize the above technical solution, the capacitor voltage intermittent working mode is specifically as follows:

[0136] When the capacitor is very small, the capacitor voltage will be zero during the entire discharge process, and the capacitor voltage will be intermittent. When the capacitor voltage is intermittent, the entire current boost circuit has three working modes. According to the critical condition of the capacitor voltage continuity and the law of conservation of energy, the following formula is obtained:

[0137]

[0138] The current equation is as follows:

[0139]

[0140] The boundary conditions for voltage continuity are as follows:

[0141]

[0142]

[0143] In order to further optimize the above technical solution, the modeling analysis of the constructed current-type DC / DC current-boosting chopper circuit by the small signal analysis method in step S3 is as follows:

[0144] Assume that IGBT and diode are ideal switches, filter inductor L is an ideal inductor, the circuit works in continuous current mode, and the load resistance is R;

[0145] When the IGBT is turned on, the state equation is:

[0146]

[0147]

[0148] When the IGBT is turned off, the diode D 1 The freewheeling conduction is on, and the state is:

[0149]

[0150]

[0151] Therefore, the average state equation of the capacitor and inductor in one cycle is:

[0152]

[0153]

[0154] In steady state, Then i s (t) = D·i L (t), U c (t)·D=i L ·R, the output current is a constant, and its magnitude is proportional to the inverse of the input current and the duty cycle.

[0155] To further optimize the above technical solution, it also includes:

[0156] The state variables of the circuit fluctuate around the steady-state value, so:

[0157]

[0158] Omitting the product of the two fluctuations, we can obtain:

[0159]

[0160] The steady-state value plus the small signal fluctuation value gives:

[0161]

[0162] Omitting the product of the two fluctuations yields:

[0163]

[0164] The input current is constant within the switching frequency band. Performing Laplace transform yields:

[0165]

[0166] but

[0167]

[0168]

[0169] eliminate get:

[0170]

[0171] That is, the control-output small signal transfer function of this converter circuit when the inductor current and capacitor voltage are continuous, then the original loop gain function G 0 As shown below:

[0172]

[0173] Among them, G vd (s) is the transfer function of the low-pass filter, V m is the peak-to-peak value of the carrier signal.

[0174] To further optimize the above technical solution, step S4 is specifically as follows:

[0175] Based on the basic principle of closed-loop control circuit, the influence of relevant parameters on the closed-loop control link is analyzed to determine the PI parameters. The output current is sampled and compared with the current reference value to obtain the error value. The error value is amplified by the PI controller. The output value is compensated and intersected with the triangular carrier, that is, the modulation wave to control the duty cycle, and then control the on and off of the switching device IGBT, so that its output current is controlled to be accurate to the reference current value.

[0176] To further optimize the above technical solution, the circuit is specifically as follows:

[0177] A current source, a capacitor connected in series with the current source, a switch S and a diode VD connected in parallel with the capacitor, and an inductor L and a resistor R connected in parallel with the diode VD.

[0178] The technical problem to be solved by the present invention is mainly a current-type DC / DC current boost circuit design and a closed-loop regulator research. First, the balance between the stability and response speed of the circuit is a key issue. In order to achieve fast response and high stability, the compensation network needs to be accurately designed, which requires a deep understanding of the dynamic characteristics of the circuit and the need to find the optimal point when adjusting the parameters. Secondly, the current-type control strategy itself has a certain complexity. Current mode control can improve dynamic response and anti-interference capabilities through inner loop current feedback, but it also introduces stability problems such as subharmonic oscillation, which need to be solved by slope compensation and other technologies. Furthermore, the impact of noise and interference in the circuit on system performance cannot be ignored. The noise in the current detection and feedback path can cause error accumulation and regulator instability, so it is necessary to design effective filtering and anti-interference measures. In addition, high-efficiency and low-power design is also a challenge. In order to improve the conversion efficiency, it is necessary to select high-performance switching devices and optimize the circuit layout to reduce switching loss and conduction loss. In summary, the design of current-type DC / DC boost circuit and its closed-loop regulator research requires comprehensive consideration and optimization in multiple aspects such as stability, dynamic response, noise processing, efficiency optimization and practical implementation in order to achieve a high-performance power conversion system.

[0179] To achieve the above object, the present invention provides the following solutions:

[0180] A current-type DC / DC current boost circuit design and closed-loop regulator research includes the following steps:

[0181] Step 1: Design and analysis of the DC-DC current boost main circuit, including: designing the main circuit schematic of the current boost chopper circuit, designing the parameters of the filter inductor in the circuit, analyzing the working mode of the current boost circuit, including the capacitor voltage continuous working mode and the capacitor voltage intermittent working mode, and finally performing a simulation analysis of the main circuit output.

[0182] Figure 1 This is the main circuit schematic diagram of the current boost chopper circuit. It consists of a DC power supply with a constant output, a fully controlled switching device IGBT or MOSFET controlled by a PWM signal, and also includes energy storage components such as capacitor C and inductor L, diode VD, load resistor R, I i is the input current, I o is the output current.

[0183] When the trigger pulse is not loaded, the IGBT is turned off, and the constant current source will be used to charge the energy storage capacitor C. After a period of time t off After that, the pulse generator outputs a positive pulse, and the IGBT is turned on. At this time, the current released by the constant current source and the capacitor C passes through the inductor together to supply power to the resistor R. The current in the inductor L gradually increases, and the voltage difference between the input and output terminals is converted into electromagnetic energy and stored. After t onAfter a certain time, the IGBT is turned off again, and the constant current source continues to charge the capacitor C. The current in the inductor L cannot change suddenly, and the self-induced electromotive force will be generated in the inductor to hinder the decrease of the current. At this time, the diode is forward-conducted, and the current in the circuit decreases slowly. The magnetic energy stored in the circuit is converted into electrical energy and released to the load. After a certain time t off Repeat the above process until the entire circuit reaches a stable state.

[0184] When the IGBT is turned on, the voltage across the inductor is V i -V o , the inductor converts electrical energy into magnetic energy and stores it, and the current increase is:

[0185]

[0186] When the IGBT is turned off, the magnetic field energy stored in the inductor is converted into electric field energy and released, and the current decreases by:

[0187]

[0188] Because when the circuit is stable, the above two currents are equal, the following formula can be obtained:

[0189]

[0190] Because in an ideal situation, the entire circuit is lossless, the input and output power are the same, and there are:

[0191] I i V i =I o V o

[0192]

[0193] Will Substituting into the above formula, we can get:

[0194]

[0195] The average value of the entire current input is I i , the average output current is I o , D is the duty cycle of the control pulse. Because theoretically, 0≤D≤1, I o ≥I i , then this circuit theoretically has the possibility of achieving an output current greater than the input current. If analyzed from the perspective of capacitance, the above formula can be obtained in the same way.

[0196] According to the requirements of the output current ripple coefficient, the filter inductance value can be calculated and then the appropriate inductance component can be selected. When the energy storage capacitor is charged, the inductor provides the charging current. Under normal circumstances, the output current ripple fluctuation range is 2%-5%. The relationship between the output current ripple peak and the inductance is shown in the following formula:

[0197]

[0198] In this article, the ripple factor is taken as 2%. In the above formula, Δi o =2%·i o The inductance value that meets the conditions can be calculated based on the above three formulas.

[0199] If the ripple fluctuation of input and output current of the current boost chopper circuit is ignored, the voltage conversion mode on the capacitor will show a linear change. The whole circuit has two working modes: continuous and discontinuous capacitor voltage. The two working modes will be analyzed one by one below.

[0200] Capacitor voltage continuous working mode

[0201] When the capacitor voltage is in a continuous state, in one working cycle of the circuit, it successively experiences the two working states of on and off. The on state of the circuit switch S is represented by 0 and, and the average value of the entire current input and output current is represented by I i and I o In this working mode, the output waveform is as follows Figure 4 As shown:

[0202] When the switch S is set to zero, that is, the circuit switch is turned off, the constant current source charges the capacitor, and the capacitor voltage increases linearly. The load resistance on the other side forms a closed loop with the diode through the freewheeling effect of the inductor, the inductor discharges, and the current in the load decreases.

[0203] When the switch S is in state 1, the entire circuit is in DT S In this case, the constant current source and the capacitor charge the load together, the capacitor voltage decreases, the capacitor discharges, the capacitor current direction is reversed, the capacitor current and the constant current source current flow through the switch tube together, and the load current increases.

[0204] When the capacitance is relatively large, the capacitance voltage is continuous. At this time, I s =D·I l , I s is the current of the current source, I l is the current in the load, D is the duty cycle, and if the capacitor voltage remains continuous, the initial and final voltages should remain consistent. When the IGBT is turned off, the power supply charges the capacitor; when it is turned on, the capacitor discharges itself, and the voltage drop during discharge should be equal to the voltage increase during charging, which is as follows:

[0205] Is ·t off =(I l -I s )·t on

[0206] From the above formula, the relationship between the output current and the input current is as follows:

[0207]

[0208] In this case, the current boost chopper circuit can work in a normal state and can achieve current amplification.

[0209] Capacitor voltage discontinuous working mode

[0210] When the capacitance is very small, the capacitor voltage will be zero during the entire discharge process, and the capacitor voltage will be intermittent. At this time, there are three working states in one working cycle of the circuit, namely, conduction, diode conduction, and capacitor discharge stop, and a single constant current source is used for power supply.

[0211] When the capacitor voltage is intermittent, the entire current boost circuit has three working modes. According to the critical condition of the capacitor voltage being continuous, the following formula is obtained through the law of conservation of energy:

[0212]

[0213] The current equation is as follows:

[0214]

[0215] According to the derivation, the boundary conditions for voltage continuity are as follows:

[0216]

[0217] After considering the capacitor voltage continuity and ripple coefficient requirements, D is set to 0.5, R = 20Ω, inductor L = 1H, C = 30×10 -5 c, period T = 0.0002s. The simulation model built in Matlab is as follows Figure 6 shown.

[0218] according to Figure 7 It can be seen that the load current reaches stability after experiencing a transient process of about 0.6 seconds, and the load output current stabilizes at around 2A, which is consistent with the theoretical analysis process. The waveforms of the load voltage and load current are consistent. Since the capacitor current needs to be charged and discharged in a complete cycle, its value alternates between positive and negative, and the amplitude is between 1 and -1.

[0219] Step 2: Derive the transfer function of the system, specifically including: In the current boost chopper circuit, there are many nonlinear elements. Applying traditional methods for modeling will encounter many inconveniences and the analysis will be relatively difficult. Small signal model establishment and state space method are two commonly used analysis methods. The present invention uses the equivalent controlled source method in the small signal model to analyze the entire circuit.

[0220] Because there is no low-frequency disturbance during the switching cycle, the AC low-frequency signal disturbance superimposed on it is much smaller than the switching frequency, so the low-frequency assumption in this circuit is met. Secondly, the turning frequency in this system is much smaller than the switching frequency, which meets the small ripple assumption. Furthermore, the amplitude of the AC component is also much smaller than the amplitude of the DC component. When the above three conditions are met, the small signal analysis method can be used for equivalent modeling.

[0221] To simplify the analysis, it is assumed that the IGBT and diode are ideal switches, the filter inductor L is an ideal inductor, the entire circuit operates in continuous current mode (CCM), and the load resistance is R.

[0222] When the IGBT is turned on, the state equation is:

[0223]

[0224]

[0225] When the IGBT is turned off, the diode D 1 The freewheeling conduction is on, and the state is:

[0226]

[0227]

[0228] Therefore, the average state equation of the capacitor and inductor in one cycle is:

[0229]

[0230]

[0231] In steady state, Then i s (t) = D·i L (t), U c (t)·D=i L ·R, the output current is a constant, and its magnitude is proportional to the inverse of the input current and the duty cycle.

[0232] Since the state variables of the circuit always fluctuate around the steady-state value, therefore:

[0233]

[0234] Omitting the product of the two fluctuations, we can obtain:

[0235]

[0236] The steady-state value plus the small signal fluctuation value can be obtained:

[0237]

[0238] Omitting the product of the two fluctuations yields:

[0239]

[0240] It is generally believed that the input current is constant within the switching frequency band, which can be assumed Performing Laplace transform yields:

[0241]

[0242] From the previous derivation, we can get:

[0243]

[0244]

[0245] eliminate available:

[0246]

[0247] This is the control-output small signal transfer function of the converter circuit when the inductor current and capacitor voltage are continuous. Then the original loop gain function G 0 As shown below:

[0248]

[0249] Substituting the previously designed parameter values, the original loop gain function is:

[0250]

[0251] Step 3: Introduce the closed-loop control principle, including: In order to make the output performance indicators of the current-boosting chopper circuit meet the corresponding stability requirements, closed-loop control is introduced to achieve the corresponding conditions so that it meets our expected requirements.

[0252] The closed-loop control system controls based on the information of the system output change, that is, by comparing the deviation between the system behavior (output) and the expected behavior, and eliminating the deviation to obtain the expected system performance. In the feedback control system, there is both a forward signal path from input to output and a feedback signal path from the output end to the input end, which form a closed loop. The closed-loop control system uses negative feedback. That is, an automatic control system with a closed loop composed of a forward signal path and a feedback path is also called a feedback control system.

[0253] The closed-loop control system has the following control characteristics: Since the feedback of the output signal is compared with the input to generate a deviation signal, the output is controlled or adjusted by using the deviation signal, so the output of the system can automatically track the input, reduce tracking errors, improve control accuracy, and suppress the influence of disturbance signals. In addition, the closed-loop control system composed of negative feedback has other advantages: after the introduction of the feedback path, the system is insensitive to changes in the parameters of the components in the forward path, so that the system does not require high accuracy for the components in the forward path; the feedback effect can also make the entire system insensitive to certain nonlinear effects. The open-loop control system cannot detect errors or correct them. The control accuracy and interference suppression performance are relatively poor, and it is very sensitive to changes in system parameters. Therefore, it is generally only used in some occasions where external influences can be ignored, or the inertia is small, or the accuracy requirements are not high. The advantage of closed-loop control is that it gives full play to the important role of feedback, eliminates unpredictable or uncertain factors, and makes the correction action more accurate and more powerful.

[0254] Step 4: Design a closed-loop regulation module based on the DC / DC current boost chopper circuit, specifically including: analyzing the influence of relevant parameters on the closed-loop control link based on the basic principle of the closed-loop control circuit, so as to determine the PI parameters.

[0255] After sampling, the output current is compared with the current reference value to obtain the error value, and the error value is amplified by the PI controller. After a certain compensation, the output value is intersected with the triangular carrier, that is, the modulation wave, to control the duty cycle, and then control the on and off of the switching device IGBT, so that its output current can be accurately close to the reference current value. Figure 8 This is the basic principle of the closed-loop control circuit.

[0256] In order to achieve the requirements of closed-loop control and further discuss the impact of relevant parameters on the closed-loop control link, a small signal method analysis model has been established. c (s), G vd (s), V m are the transfer function of the compensator, the low-pass filter and the peak-to-peak value of the carrier signal. The PWM transfer function is easy to understand: Using the small signal model analysis, the entire loop gain can be obtained as

[0257] The open-loop transfer function is brought into the program, and the program applies the principles of trial and error and linear convolution to output its open-loop Bode diagram to observe whether its phase margin meets the requirements, as well as the root locus and bandwidth in the closed-loop mode.

[0258] The results show that the phase margin is 45.9 degrees and the bandwidth is 196 Hz. At the same time, the results are p = 11 and I = 11000. The PI parameters are determined.

[0259] Step 5: DC / DC current boost chopper circuit simulation analysis, including: building a simulation model in MATLAB / Simulink software, and verifying the system bandwidth through output step response.

[0260] In transient conditions, the initial value is 2, and the step value is 5 at the 5th second. The output current waveform is shown in the figure. It can be seen that the output current tracks quickly and quickly tracks the step current. The tracking ability of the circuit model is stable.

[0261] according to Fig.10 The phase margin of the closed-loop transfer function shown meets the requirements very well. The bandwidth is 196 Hz, which meets the response requirements very well and has a fast response speed. However, according to the closed-loop root locus diagram, there are zero poles on the right side of the y-axis, and the stability is poor.

[0262] The present invention discloses a current type DC / DC current boost circuit design and a closed-loop regulator research. Power electronics technology has become one of the important basic technologies in my country's national economy. Modern power electronics technology is becoming more and more mature, but in DC-DC power conversion, there is currently a lack of effective conversion circuits for DC current source current boost. In this paper, a DC-DC current boost chopper conversion circuit is derived and designed by analogy with the step-down chopper circuit, and its working principle and potential application environment are systematically and detailedly explained. A specific equivalent model is constructed to conduct a detailed and detailed analysis of its different working states; a closed-loop regulator is established for the current boost circuit, and the root locus and Burdett are used to perform stability analysis to make it meet the conditions of an amplitude margin of 45 degrees and a system bandwidth of 200Hz. Finally, a simulation model is built in MATLAB / Simulink software, and the system bandwidth is verified by outputting a step response.

[0263] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0264] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A current-type DC / DC current boost chopper circuit construction and simulation correction method, characterized in that: include: Step S1, constructing a current-type DC / DC current-boosting chopper circuit, and determining the parameters of each component in the circuit; Step S2, based on the constructed current-type DC / DC current-boosting chopper circuit, simulating its working mode; Step S3, modeling and analyzing the constructed current-source DC / DC current-boosting chopper circuit by a small signal analysis method; Step S4: construct a closed loop of the current-source DC / DC current-boosting chopper circuit, and calibrate the current-source DC / DC current-boosting chopper circuit.

2. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 1, characterized in that: The construction of the current-type DC / DC current-boosting chopper circuit described in step S1 is specifically as follows: The current-type DC / DC current-boosting chopper circuit includes a DC power supply with a constant output, a fully controlled switching device IGBT or MOSFET controlled by a PWM signal, and also includes energy storage elements such as a capacitor C and an inductor L, a diode VD, and a load resistor R; When the trigger pulse is not loaded, the IGBT is turned off, and the constant current source will be used to charge the energy storage capacitor C. After a period of time t off After that, the pulse generator outputs a positive pulse, and the IGBT is turned on. At this time, the current released by the constant current source and the capacitor C passes through the inductor together to supply power to the resistor R. The current in the inductor L gradually increases, and the voltage difference between the input and output terminals is converted into electromagnetic energy and stored. After t on After a certain time, the IGBT is turned off again, and the constant current source continues to charge the capacitor C. The current in the inductor L cannot change suddenly, and the self-induced electromotive force will be generated in the inductor to hinder the decrease of the current. At this time, the diode is forward-conducted, and the current in the circuit decreases slowly. The magnetic energy stored in the circuit is converted into electrical energy and released to the load. After a certain time t off Repeat the above process until the entire circuit reaches a stable state.

3. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 2, characterized in that: The parameters of each component in the determination circuit are specifically: When the IGBT is turned on, the voltage across the inductor is V i -V o , the inductor converts electrical energy into magnetic energy and stores it, and the current increases by ΔI L1 for: Where L is the inductance, V L is the inductor voltage, V i is the voltage at the inductor input terminal, V o is the voltage at the inductor output terminal; When the IGBT is turned off, the magnetic field energy stored in the inductor is converted into electric field energy and released, and the current decreases by ΔI L2 for: Because when the circuit is stable, the above two currents are equal, then: Assuming the circuit is lossless and the input and output powers are the same, then: I i V i =I o V o but Will Substituting into the above formula, we can get: Among them, the average value of the entire current input is I i , the average output current is I o , D is the duty cycle of the control pulse; The filter inductance value is calculated based on the ripple coefficient requirement for the output current. The relationship between the output current ripple peak and the inductance is shown in the following formula:

4. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 1, characterized in that: Based on the constructed current-type DC / DC current boost chopper circuit, its working mode is simulated, and the working mode includes a capacitor voltage continuous working mode and a capacitor voltage discontinuous working mode.

5. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 4, characterized in that: The capacitor voltage continuous working mode is specifically: When the capacitor voltage is in a continuous state, it goes through two working states, on and off, in one working cycle of the circuit. The on state of the circuit switch is represented by 0 and 1, and the average value of the entire current input is I i and the average output current is I o ; When the switch is set to zero, that is, the circuit switch is turned off, the constant current source charges the capacitor, and the capacitor voltage increases linearly. The load resistor on the other side forms a closed loop with the diode through the freewheeling effect of the inductor, the inductor discharges, and the current in the load decreases; When the switch is in state 1 and the entire circuit is in state, the constant current source and the capacitor charge the load together, the capacitor voltage decreases, the capacitor discharges, the capacitor current direction is reversed, the capacitor current and the constant current source current flow through the switch tube together, and the load current increases; When the capacitance is relatively large, the capacitance voltage is continuous, so I s =D·I l , I s is the current of the current source, I l is the current in the load, D is the duty cycle, if the capacitor voltage remains continuous, the initial and final voltages remain consistent, when it is turned off, the power supply charges the capacitor; when it is turned on, the capacitor discharges itself, and the voltage drop during discharge should be equal to the voltage increase during charging, which is as follows: I s ·t off =(I l -I s )·t on Then the relationship between the output current and the input current is:

6. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 4, characterized in that: The capacitor voltage intermittent working mode is specifically: When the capacitor is very small, the capacitor voltage will be zero during the entire discharge process, and the capacitor voltage will be intermittent. When the capacitor voltage is intermittent, the entire current boost circuit has three working modes. According to the critical condition of the capacitor voltage continuity and the law of conservation of energy, the following formula is obtained: The current equation is as follows: The boundary conditions for voltage continuity are as follows:

7. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 1, characterized in that: The modeling and analysis of the constructed current-type DC / DC boost chopper circuit by the small signal analysis method described in step S3 is specifically as follows: Assume that IGBT and diode are ideal switches, filter inductor L is an ideal inductor, the circuit works in continuous current mode, and the load resistance is R; When the IGBT is turned on, the state equation is: When the IGBT is turned off, the diode D1 is turned on and the state is: Therefore, the average state equation of the capacitor and inductor in one cycle is: In steady state, Then i s (t) = D·i L (t), U c (t)·D=i L ·R, the output current is a constant, and its magnitude is proportional to the inverse of the input current and the duty cycle.

8. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 7, characterized in that: Furthermore, it also includes: The state variables of the circuit fluctuate around the steady-state value, so: Omitting the product of the two fluctuations, we can obtain: The steady-state value plus the small signal fluctuation value gives: Omitting the product of the two fluctuations yields: The input current is constant within the switching frequency band. Performing Laplace transform yields: but eliminate get: That is, the control-output small signal transfer function of this converter circuit when the inductor current and capacitor voltage are continuous, and the original loop gain function G0 is as follows: Among them, G vd (s) is the transfer function of the low-pass filter, V m is the peak-to-peak value of the carrier signal.

9. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 1, characterized in that: The step S4 is specifically as follows: Based on the basic principle of closed-loop control circuit, the influence of relevant parameters on the closed-loop control link is analyzed to determine the PI parameters. The output current is sampled and compared with the current reference value to obtain the error value. The error value is amplified by the PI controller. The output value is compensated and intersected with the triangular carrier, that is, the modulation wave to control the duty cycle, and then control the on and off of the switching device IGBT, so that its output current is controlled to be accurate to the reference current value.

10. The method for constructing and simulating a current-source DC / DC current-boosting chopper circuit according to claim 1, characterized in that: The circuit is specifically: A current source, a capacitor connected in series with the current source, a switch S and a diode VD connected in parallel with the capacitor, and an inductor L and a resistor R connected in parallel with the diode VD.

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