A step-up DC-DC converter with open-loop stable operation under constant power load and its control system

Abstract

The invention discloses a boost DC-DC converter and a control system capable of operating stably in an open loop under a constant power load, and belongs to the technical field of boost converters. The positive electrode of an external voltage source is connected to the same-name end of a first coupled inductor coil, the non-same-name end of the first coupled inductor coil is connected to the positive electrode of a first diode, the drain of a power switch tube and the positive electrode of a second diode, one end of a first capacitor is connected to the negative electrode of the first diode and the same-name end of a second coupled inductor coil, the negative electrode of the second diode is connected to the non-same-name end of the second coupled inductor coil, one end of the second capacitor and one end of an external constant power load, the negative electrode of the external voltage source is connected to the source of the power switch tube, the other end of the first capacitor, the other end of the second capacitor and the other end of the external constant power load, and the converter and the control system can operate stably in an open loop under a constant power load.

Description

Technical Field

[0001] The invention belongs to the technical field of boost converters, and relates to a boost DC-DC converter with open-loop stable operation under constant power load and a control system thereof. Background Art

[0002] Constant power load is a type of load widely found in the actual engineering field. For example, Song Xinda et al. pointed out in the document “Control Method of Constant Power Load System Based on Virtual Damping Compensation” (Journal of Electric Machines and Control, 2016, 20(8): 1-9): In the DC / DC power module driving motor system of new energy vehicles, when the motor speed is constant in steady state, it can be regarded as a constant power load. Du Wenjing et al. pointed out in the document “Dynamic Response Analysis of DC-DC Converter with Constant Power Load and Stability Prediction of Cascade System” (Transactions of China Electrotechnical Society, 2011, 26(Supplement 1): 83-90.): In order to meet the power demand of the electronic equipment of new energy vehicles, in order to improve the conversion efficiency of power conversion within a wide input voltage range, a two-stage DC-DC power supply cascade structure is often used. The front stage is a pre-regulator, which can optimize the efficiency of the entire system, and the DC / DC power module with closed-loop regulation in the rear stage can be equivalent to a constant power load. Zhou Suying et al. stated in the paper “Load Stability Analysis of Power System of More-Electric Aircraft” (Aviation Computing Technology, 2002, 32(4): 93-95) that the power electronic converters and electric actuators widely used in more-electric and all-electric aircraft systems can generally be regarded as constant power loads. Zhou Jiemin et al. predicted in the paper “Simulation Research on Constant Power Load of More-Electric Aircraft Based on Simplorer” (Journal of Chongqing University of Technology (Natural Science), 2016, 30(5): 102-107) that in the future more-electric and all-electric aircraft high voltage DC power distribution systems, about 75% of the loads will be constant power loads.

[0003] Under constant power load, the increase of voltage across the load means the decrease of current to keep the load power unchanged. Therefore, the constant power load has negative impedance characteristics, so that the DC-DC converter driving the constant power load in an open loop is in an unstable state. To solve this problem, the main approaches in the past were to consider the parasitic parameters of the DC-DC converter and design the controller.

[0004] For a DC-DC converter driving a constant power load without considering parasitic parameters, when it is in open-loop control and the inductor current is in continuous mode, the system is in an unstable state. For example, Vlad Grigore et al. in the literature "Dynamics of a Buck converter with a constant power load" (29th Annual IEEE Power Electronics Specialists Conference (PESC), Fukuoka, Japan, 1998, 72-78) analyzed the Buck DC-DC converter in the open-loop control inductor current continuous mode without considering parasitic parameters and found that the Buck DC-DC converter under constant power load is unstable in the entire parameter domain. The research results of Li Yushan et al. in the literature "Current mode control for Boost converters with constant power loads" show that when the load of the Boost DC-DC converter under open-loop control without considering parasitic parameters is a constant power load, it is also in an unstable state in the entire parameter domain.

[0005] When a DC-DC converter driving a constant power load with parasitic parameters is considered, although the system can be kept in an open-loop stable state within a limited parameter domain, the value of the parasitic parameters is generally small, so that its stable region is very limited. For example, Khaligh Alireza et al. studied the influence of parasitic parameters (including the on-resistance of the power switch, the on-resistance of the diode, the series equivalent resistance of the inductor, etc.) on the stability of an open-loop controlled Buck DC-DC converter driving a constant power load in the document "Realization of parasitics in stability of DC-DC converters loaded by constant power loads in advanced multiconverterautomotive systems" (IEEE Transactions on Industrial Electronics, 2008, 55(6):2295-2305) and pointed out that: in the open-loop working mode, when considering the existence of component parasitic parameters, although the Buck DC-DC converter with a constant power load can be made stable within a certain parasitic parameter range, the parameter values ​​of the parasitic parameters are generally small, resulting in a very small parameter stability range.

[0006] Therefore, exploring DC-DC converters that can operate stably in open loop under constant power load is of great significance to the drive design of constant power load and has always been a hot topic in industry research. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a boost DC-DC converter and its control system that can operate stably in an open loop under a constant power load. The converter and its control system can operate stably in an open loop under a constant power load.

[0008] To achieve the above object, the present invention discloses a step-up DC-DC converter with open-loop stable operation under constant power load, comprising a first coupled inductor, a first diode, a power switch tube, a second diode, a second coupled inductor, a first capacitor and a second capacitor;

[0009] The positive electrode of the external voltage source is connected to the same-name end of the first coupled inductor coil, the non-same-name end of the first coupled inductor coil is connected to the positive electrode of the first diode, the drain of the power switch tube and the positive electrode of the second diode, one end of the first capacitor is connected to the negative electrode of the first diode and the same-name end of the second coupled inductor coil, the negative electrode of the second diode is connected to the non-same-name end of the second coupled inductor coil, one end of the second capacitor and one end of the external constant power load, and the negative electrode of the external voltage source is connected to the source of the power switch tube, the other end of the first capacitor, the other end of the second capacitor and the other end of the external constant power load.

[0010] The further improvement of the step-up DC-DC converter with open-loop stable operation under constant power load described in the present invention is:

[0011] Furthermore, the output voltage of the external voltage source V i and the voltage across the external constant power load V The relationship of 2 is:

[0012]

[0013] in, D is the duty cycle of the power switch.

[0014] Furthermore, D ∈(0, 1).

[0015] Furthermore, the power switch tube is a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a gate turn-off thyristor, an integrated gate commutated thyristor or a MOS controlled thyristor.

[0016] The present invention discloses a control system, comprising a controller and a boost DC-DC converter with open-loop stable operation under a constant power load, wherein the boost DC-DC converter with open-loop stable operation under a constant power load comprises a first coupled inductor, a first diode, a power switch tube, a second diode, a second coupled inductor, a first capacitor and a second capacitor, and the output end of the controller is connected to the gate of the power switch tube Q in the boost DC-DC converter with open-loop stable operation under a constant power load.

[0017] The further improvement of the control system of the present invention is:

[0018] Furthermore, when working, the controller outputs a PWM signal and inputs the PWM signal to the gate of the power switch tube.

[0019] Furthermore, the voltage across the external constant power load is adjusted by adjusting the duty cycle of the PWM signal. V 2.

[0020] Furthermore, the output voltage of the external voltage source V i and the voltage across the external constant power load V The relationship of 2 is:

[0021]

[0022] in, D is the duty cycle of the power switch.

[0023] Furthermore, D ∈(0, 1).

[0024] Furthermore, the power switch tube is a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a gate turn-off thyristor, an integrated gate commutated thyristor or a MOS controlled thyristor.

[0025] The present invention has the following beneficial effects:

[0026] In the specific operation of the boost DC-DC converter with open-loop stable operation under constant power load and the control system thereof described in the present invention, the output end of the controller is connected to the gate of the power switch tube in the boost DC-DC converter with open-loop stable operation under constant power load. In the boost DC-DC converter with open-loop stable operation under constant power load, only one active device needs to be controlled, namely the power switch tube. Therefore, boosting can be achieved by controlling the power switch tube, and open-loop stable operation can be achieved under constant power load, which is suitable for driving constant power load requirements. In addition, according to experiments, the converter described in the present invention can achieve open-loop stable operation under an external constant power load P0, and is extremely practical.

[0027] Furthermore, when working, the controller outputs a PWM signal and inputs the PWM signal to the gate of the power switch tube, and adjusts the voltage across the external constant power load by adjusting the duty cycle of the PWM signal. V 2. Easy and simple operation, highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 It is a structural diagram of the present invention;

[0030] Figure 2a is the voltage on the second capacitor C2 in the verification test V 2. Plot of changes over time;

[0031] Figure 2b is the voltage on the first capacitor C1 in the verification test V 1. Plot of changes over time;

[0032] Figure 2c This is a graph showing the variation of the inductor current i1 on the first coupled inductor L1 with time in the verification test;

[0033] Figure 2d is a graph showing the variation of the inductor current i2 on the second coupled inductor L2 with time in the verification test;

[0034] Figure 2e This is the PWM signal of the power switch Q in the verification test. V p Graph of changes over time. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0036] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0037] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0038] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0039] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0042] Embodiment 1

[0043] refer to Figure 1The step-up DC-DC converter with open-loop stable operation under constant power load of the present invention comprises a first coupled inductor L1, a first diode D1, a power switch tube Q, a second diode D2, a second coupled inductor L2, a first capacitor C1 and a second capacitor C2;

[0044] External voltage source V n The positive electrode of is connected to the same-name end of the first coupled inductor L1, the non-same-name end of the first coupled inductor L1 is connected to the positive electrode of the first diode D1, the drain of the power switch tube Q and the positive electrode of the second diode D2, one end of the first capacitor C1 is connected to the negative electrode of the first diode D1 and the same-name end of the second coupled inductor L2, the negative electrode of the second diode D2 is connected to the non-same-name end of the second coupled inductor L2, one end of the second capacitor C2 and one end of the external constant power load P0, the external voltage source V n The negative electrode is connected to the source of the power switch tube Q, the other end of the first capacitor C1, the other end of the second capacitor C2 and the other end of the external constant power load P0.

[0045] As an implementation mode of the present invention, the power switch tube Q is a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a gate turn-off thyristor, an integrated gate commutated thyristor or a MOS controlled thyristor.

[0046] As an implementation mode of the present invention, the power switch tube Q is driven by a PWM signal with a duty cycle of D, D∈(0, 1), then the external voltage source V n Output voltage V i The voltage across the external constant power load P0 V The relationship of 2 is:

[0047] .

[0048] Embodiment 2

[0049] The present embodiment discloses a control system of a boost DC-DC converter with open-loop stable operation under constant power load, including a controller, wherein the boost DC-DC converter with open-loop stable operation under constant power load includes a first coupled inductor L1, a first diode D1, a power switch tube Q, a second diode D2, a second coupled inductor L2, a first capacitor C1 and a second capacitor C2; an external voltage source V nThe positive electrode of is connected to the same-name end of the first coupled inductor L1, the non-same-name end of the first coupled inductor L1 is connected to the positive electrode of the first diode D1, the drain of the power switch tube Q and the positive electrode of the second diode D2, one end of the first capacitor C1 is connected to the negative electrode of the first diode D1 and the same-name end of the second coupled inductor L2, the negative electrode of the second diode D2 is connected to the non-same-name end of the second coupled inductor L2, one end of the second capacitor C2 and one end of the external constant power load P0, the external voltage source V n The negative electrode is connected to the source of the power switch tube Q, the other end of the first capacitor C1, the other end of the second capacitor C2 and the other end of the external constant power load P0, and the output end of the controller is connected to the gate of the power switch tube Q.

[0050] The working process of the control system of the boost DC-DC converter with open-loop stable operation under constant power load is as follows:

[0051] The controller outputs a PWM signal and inputs the PWM signal to the gate of the power switch tube Q. By adjusting the duty cycle of the PWM signal, the voltage across the external constant power load P0 is adjusted. V 2, where the external voltage source V n Output voltage V i and the voltage across the external constant power load P0 V The relationship of 2 is:

[0052]

[0053] in, D is the duty cycle of the power switch tube Q, D ∈(0, 1).

[0054] In this embodiment, the power switch tube Q is a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a gate turn-off thyristor, an integrated gate-commutated thyristor or a MOS-controlled thyristor.

[0055] It should be noted that the boost DC-DC converter with open-loop stable operation under constant power load described in the present invention includes a first coupled inductor L1, a first diode D1, a power switch tube Q, a second diode D2, a second coupled inductor L2, a first capacitor C1 and a second capacitor C2, wherein only one active device needs to be controlled, namely the power switch tube Q. In actual work, it is only necessary to control the power switch tube Q through a controller to achieve boost and open-loop stable operation under constant power load. The operation is simple and convenient, and the practicability is extremely strong. It can be applied to occasions of driving constant power load.

[0056] Confirmatory test

[0057] To verify the present invention, a simulation model of the present invention is built in PSIM software. In a specific implementation, the external voltage source V n The output voltage is 48V, the inductance of the first coupled inductor L1 is 2mH, the inductance of the second coupled inductor L2 is 2mH, the mutual inductance of the first coupled inductor L1 and the second coupled inductor L2 is 1.5mH, the capacitance of the first capacitor C1 is 4.7μF, the capacitance of the second capacitor C2 is 47μF, the external constant power load P0 is 30W, the switching frequency is 50kHz, and the duty cycle D is 0.4. In addition, in the simulation model, the simulation model of the external constant power load P0 is constructed by controlling the current source with voltage.

[0058] To verify the present invention, the simulation results when the duty cycle D=0.4 are as follows: Figure 2a to Figure 2e As shown, the waveforms from top to bottom are: the voltage of the second capacitor C2 V 2, that is, the output voltage, the voltage of the first capacitor C1 V 1, the inductor current i1 of the first coupled inductor L1, the inductor current i2 of the second coupled inductor L2, the PWM signal of the power switch tube Q V p .from Figure 2a to Figure 2e It can be seen that the voltage of the second capacitor C2 V 2. The voltage of the first capacitor C1 V 1. The inductor current i1 of the first coupled inductor L1 and the inductor current i2 of the second coupled inductor L2 are all stable, indicating that the converter of the present invention can achieve open-loop stable operation under the external constant power load P0.

[0059] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0060] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A step-up DC-DC converter with open-loop stable operation under constant power load, characterized in that: It comprises a first coupled inductor (L1), a first diode (D1), a power switch tube (Q), a second diode (D2), a second coupled inductor (L2), a first capacitor (C1) and a second capacitor (C2); External voltage source (V n ) is connected to the same-name end of the first coupled inductor (L1), the non-same-name end of the first coupled inductor (L1) is connected to the positive electrode of the first diode (D1), the drain of the power switch tube (Q) and the positive electrode of the second diode (D2), one end of the first capacitor (C1) is connected to the negative electrode of the first diode (D1) and the same-name end of the second coupled inductor (L2), the negative electrode of the second diode (D2) is connected to the non-same-name end of the second coupled inductor (L2), one end of the second capacitor (C2) and one end of the external constant power load (P0), and the external voltage source (V n ) is connected to the source of the power switch tube (Q), the other end of the first capacitor (C1), the other end of the second capacitor (C2) and the other end of the external constant power load (P0).

2. The step-up DC-DC converter with open-loop stable operation under constant power load according to claim 1, characterized in that: External voltage source (V n ) output voltage V i The voltage across the external constant power load (P0) V The relationship of 2 is: in, D is the duty cycle of the power switch tube (Q).

3. The step-up DC-DC converter with open-loop stable operation under constant power load according to claim 2, characterized in that: D ∈(0, 1)。 4. The step-up DC-DC converter with open-loop stable operation under constant power load according to claim 1, characterized in that: The power switch tube (Q) is a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a gate turn-off thyristor, an integrated gate commutated thyristor or a MOS controlled thyristor.

5. A control system, characterized in that: It comprises a controller and the step-up DC-DC converter with open-loop stable operation under constant power load as claimed in claim 1, wherein the output end of the controller is connected to the gate of a power switch tube (Q) in the step-up DC-DC converter with open-loop stable operation under constant power load.

6. The control system according to claim 5, characterized in that: When working, the controller outputs a PWM signal and inputs the PWM signal to the gate of the power switch tube (Q).

7. The control system according to claim 6, characterized in that: By adjusting the duty cycle of the PWM signal, the voltage across the external constant power load (P0) is adjusted. V 2.

8. The control system according to claim 7, characterized in that: External voltage source (V n ) output voltage V i and the voltage across the external constant power load (P0) V The relationship of 2 is: in, D is the duty cycle of the power switch tube (Q).

9. The control system according to claim 8, characterized in that D ∈(0, 1)。 10. The control system according to claim 5, characterized in that: The power switch tube (Q) is a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a gate turn-off thyristor, an integrated gate commutated thyristor or a MOS controlled thyristor.

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