Current sharing control system for dc-dc converter, dc-dc converter system and control method

Abstract

The application relates to a current sharing control system of a DCDC converter, a DCDC converter system and a control method. The current sharing control system comprises a control circuit connected in one-to-one correspondence with each power conversion circuit. The control circuit comprises: a first feedforward unit configured to receive a first current signal representing a load current of the power conversion circuit, generate a first voltage compensation signal according to the first current signal, and provide a reference compensation amount in a steady state; a second feedforward unit configured to generate a second voltage compensation signal according to the first current signal, and provide a transient compensation amount associated with a change rate when the load current changes; and a reference voltage correction unit configured to superimpose the first voltage compensation signal and the second voltage compensation signal on a voltage reference signal, and provide the superimposed reference voltage to a voltage control loop. The application can effectively eliminate transient circulating current and realize the unity of steady-state current sharing and dynamic current sharing.

Description

Technical Field

[0001] This application relates to the field of converter control technology, and in particular to a current sharing control system for a DC-DC converter, a DC-DC converter system, and a control method. Background Technology

[0002] With the continuous development of science and technology, high-performance, high-power DC power supplies have gradually become a critical infrastructure. Limited by the rated current and thermal bottlenecks of single power modules, a single DC-DC converter can hardly meet high power demands. In practice, a parallel Buck converter architecture is often used as a solution for high-power power supplies. In a parallel Buck converter system, the core control objective is current distribution, i.e., current sharing control among the power conversion modules.

[0003] Virtual impedance technology can be used in related technologies. Specifically, it involves introducing additional feedback variables, such as current feedback, into the control loop to adjust the equivalent output impedance characteristics of the parallel Buck converter system, thereby meeting the required current sharing requirements. However, virtual impedance technology is mostly based on steady-state phasor models or average models, ignoring the high-frequency characteristics of the output LC. Although it can solve the steady-state current sharing problem, the system performance during high-frequency dynamic processes is mainly limited by physical hardware parameters, making it difficult to effectively suppress transient circulating currents caused by the difference in physical inertia between inductors and capacitors during load steps. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a current sharing control system, a DC-DC converter system and a control method for a DC-DC converter to solve at least one problem existing in the background art, which can effectively eliminate transient circulating current and achieve the unity of steady-state current sharing and dynamic current sharing.

[0005] In a first aspect, embodiments of this application provide a current sharing control system for a DC-DC converter, wherein the DC-DC converter includes at least two power conversion circuits connected in parallel, and the current sharing control system includes control circuits connected one-to-one with the power conversion circuits; each of the control circuits includes:

[0006] A voltage control loop configured to generate a current reference signal based on the difference between a voltage reference signal and the output voltage feedback signal of the power conversion circuit;

[0007] A current control loop is configured to generate a switch drive signal based on the difference between the current reference signal and the inductor current feedback signal of the power conversion circuit, the switch drive signal being used to control the power switch of the power conversion circuit.

[0008] A first feedforward unit is configured to receive a first current signal characterizing the load current of the power conversion circuit, and generate a first voltage compensation signal based on the first current signal. The first feedforward unit has a preset constant amplitude, so that the first voltage compensation signal provides a reference compensation amount in steady state.

[0009] The second feedforward unit is configured to receive the first current signal and generate a second voltage compensation signal based on the first current signal. The second feedforward unit has a preset frequency characteristic so that the second voltage compensation signal provides a transient compensation amount related to the rate of change when the load current changes.

[0010] A reference voltage correction unit is configured to negatively superimpose the first voltage compensation signal and positively superimpose the second voltage compensation signal onto the voltage reference signal, and provide the reference voltage after superimposing the first voltage compensation signal and the second voltage compensation signal to the voltage control loop.

[0011] In conjunction with the first aspect of this application, in an alternative embodiment, the DC-DC converter includes a Buck converter.

[0012] In conjunction with the first aspect of this application, in an alternative embodiment, the first current signal is the inductor current signal of the power conversion circuit.

[0013] In conjunction with the first aspect of this application, in an optional embodiment, the transfer function of the first feedforward unit is G. comp1 =R v1 , where R v1 This is the first preset virtual resistance value.

[0014] In conjunction with the first aspect of this application, in an optional embodiment, the transfer function of the second feedforward unit is G. comp2 =(R v2 +L v ·s)·ω c / (s+ω c ), where R v2 R is the second preset virtual resistance value. v2 <R v1 L v To preset the virtual inductance value, ω c s is the cutoff frequency of the preset virtual low-pass filter, and s is the Laplace operator.

[0015] In conjunction with the first aspect of this application, in an optional embodiment, the first feedforward unit and the second feedforward unit are implemented by a digital control algorithm.

[0016] In conjunction with the first aspect of this application, in an optional embodiment, the voltage control loop includes a voltage regulator, the current control loop includes a current regulator, and both the voltage regulator and the current regulator are proportional-integral regulators.

[0017] Secondly, embodiments of this application provide a DC-DC converter system, characterized in that it includes a DC-DC converter and a current sharing control system for the DC-DC converter as described in the first aspect, wherein the DC-DC converter includes at least two power conversion circuits connected in parallel, and the current sharing control system includes control circuits of the same number as the power conversion circuits, wherein the control circuits are connected one-to-one with the power conversion circuits.

[0018] Thirdly, embodiments of this application provide a current sharing control method for a DC-DC converter, characterized in that it is applied to a current sharing control system for a DC-DC converter as described in the first aspect, the current sharing control method comprising:

[0019] The first current signal characterizing the load current of the power conversion circuit is received, and a first voltage compensation signal is generated based on the first current signal. The first feedforward unit has a preset constant amplitude, so that the first voltage compensation signal provides a reference compensation amount in steady state.

[0020] The first current signal is received, and a second voltage compensation signal is generated based on the first current signal. The second feedforward unit has a preset frequency characteristic, so that the second voltage compensation signal provides a transient compensation amount related to the rate of change when the load current changes.

[0021] The first voltage compensation signal is superimposed negatively onto the voltage reference signal, and the second voltage compensation signal is superimposed positively.

[0022] A current reference signal is generated based on the difference between the reference voltage after superimposing the first voltage compensation signal and the second voltage compensation signal and the output voltage feedback signal of the power conversion circuit.

[0023] A switch drive signal is generated based on the difference between the current reference signal and the inductor current feedback signal of the power conversion circuit. The switch drive signal is used to control the power switch of the power conversion circuit.

[0024] In conjunction with the first aspect of this application, in an optional embodiment, generating the first voltage compensation signal based on the first current signal includes:

[0025] The first current signal is transformed by the transfer function of the first feedforward unit to generate the first voltage compensation signal. The transfer function of the first feedforward unit is G. comp1 =R v1 , where Rv1 The first preset virtual resistance value; and,

[0026] The step of generating a second voltage compensation signal based on the first current signal includes:

[0027] The first current signal is transformed by the transfer function of the second feedforward unit to generate the second voltage compensation signal. The transfer function of the second feedforward unit is G. comp2 =(R v2 +L v ·s)·ω c / (s+ω c ), where R v2 R is the second preset virtual resistance value. v2 <R v1 L v To preset the virtual inductance value, ω c s is the cutoff frequency of the preset virtual low-pass filter, and s is the Laplace operator.

[0028] The current sharing control system for the DC-DC converter provided in this application embodiment includes at least two control circuits. Each control circuit is connected one-to-one with a single power conversion circuit in the DC-DC converter. Each control circuit includes a voltage control loop, a current control loop, a first feedforward unit, a second feedforward unit, and a reference voltage correction unit. That is, based on the voltage control loop and the current control loop, the first feedforward unit and the second feedforward unit are introduced to provide a reference compensation amount based on the load current of the power conversion circuit and a transient compensation amount based on the load current of the power conversion circuit. All values ​​are superimposed on the reference voltage, resulting in low computational complexity. The first feedforward unit, acting as a negative feedforward compensation path, can establish a steady-state current sharing rule through the reference compensation amount. The second feedforward unit, acting as a positive feedforward compensation path, can actively cancel the inertia of the physical LC filter through the transient compensation amount. This can solve the dynamic impedance mismatch caused by the deviation of the filter LC parameters during load step, thereby effectively eliminating transient circulating current. The positive and negative synergistic effect with the first feedforward unit can significantly improve the current distribution performance during dynamic processes while maintaining the steady-state current sharing capability of droop control. This achieves the unity of steady-state current sharing and dynamic current sharing, and the computational complexity is low.

[0029] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 This is a structural diagram of a single power conversion circuit;

[0032] Figure 2 This is a block diagram of the current sharing control system of a DC-DC converter provided in an embodiment of this application;

[0033] Figure 3 A detailed structural block diagram of the current sharing control system for a DC-DC converter provided in the embodiments of this application;

[0034] Figure 4 This is a simplified schematic diagram of a dual-parallel Buck converter;

[0035] Figure 5(a) and Figure 5(b) are the response waveforms of the output voltage and the load current of each branch of the DC-DC converter (without current sharing control) under the load step loading and unloading conditions, respectively.

[0036] Figures 5(c) and 5(d) are the response waveforms of the output voltage and the load current of each branch of the DC-DC converter system provided in the embodiments of this application under the load step loading condition and the load unloading condition, respectively.

[0037] Figures 6(a) and 6(b) are the response waveforms of the output voltage and the load current of each branch of another DC-DC converter (only the first feedforward unit) under the load step loading condition and the unloading condition, respectively.

[0038] Figures 6(c) and 6(d) are the response waveforms of the output voltage and the load current of each branch of another DC-DC converter provided in the embodiments of this application under the step loading and unloading conditions.

[0039] Figures 7(a) and 7(b) are the response waveforms of the output voltage and the load current of each branch of another DC-DC converter provided in the embodiment of this application under the condition of step loading and unloading of the load when the output inductance deviation is 20%.

[0040] Figures 7(c) and 7(d) are the response waveforms of the output voltage and the load current of each branch of another DC-DC converter provided in the embodiments of this application under the conditions of step loading and unloading of the load when the output capacitor deviation is 20%. Detailed Implementation

[0041] To make the technical solution and beneficial effects of this application more apparent and understandable, a detailed description is provided below by listing specific embodiments. The accompanying drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application pertains.

[0042] This application provides a current sharing control system for a DC-DC converter, applied to a DC-DC converter system. The DC-DC converter system includes a DC-DC converter and a current sharing control system. The DC-DC converter can be a Buck converter, a Boost converter, etc. The DC-DC converter includes at least two power conversion circuits connected in parallel. In this embodiment, the DC-DC converter can be a Buck converter, specifically adopting a dual-parallel Buck converter architecture, that is, the DC-DC converter has two power conversion circuits, and the output terminals of the two power conversion circuits are connected to the same output bus. The current sharing control system includes control circuits connected one-to-one with the power conversion circuits, that is, each power conversion circuit is controlled independently.

[0043] like Figure 1 As shown, the power conversion circuit includes switching transistors Q1 and Q2, input capacitor C1, output inductor L, and output capacitor C2. Switches Q1 and Q2 can be N-type MOSFETs. Diode D1 is connected in reverse parallel across Q1, and diode D2 is connected in reverse parallel across Q2. Switches Q1 and Q2 are the upper and lower transistors, respectively. Switch Q1 is positioned at the input voltage V. i The positive terminal of the capacitor is connected to the output inductor L, and the other end of the output inductor L is connected to the positive terminal of the output capacitor C2. The negative terminal of the output capacitor C2 is connected to the reference ground. The voltage across the output capacitor C2 is the output voltage V. o The output inductor L and output capacitor C2 are cascaded to form a second-order LC filter, and the switching transistor Q2 is located at the midpoint between the upper and lower transistors and the input voltage V. i Between the negative terminals, the input capacitor C1 is connected to the input voltage V. i Between the positive and negative terminals, the input voltage V i The negative terminal and output voltage V o The negative terminal is connected to the reference ground.

[0044] like Figure 2 and Figure 3 As shown, each control circuit includes a voltage control loop and a current control loop G. close_i(s) First feedforward unit, second feedforward unit, and reference voltage correction unit. Considering that the operating principles of each control circuit are the same, this application embodiment provides a detailed description of a power conversion circuit and the control circuit connected to that power conversion circuit.

[0045] In some embodiments, the voltage control loop is configured to generate a current reference signal based on the difference between a voltage reference signal and the output voltage feedback signal of the power conversion circuit. The current control loop is configured to generate a switch drive signal based on the difference between the current reference signal and the inductor current feedback signal of the power conversion circuit; the switch drive signal is used to control the power switching of the power conversion circuit.

[0046] Furthermore, the voltage control loop includes a voltage regulator, and the current control loop includes a current regulator. Both the voltage regulator and the current regulator are proportional-integral (PI) regulators, with the voltage regulator being a PI regulator. cv (s), the current regulator is a PI regulator G ci (s).

[0047] The voltage control loop acquires the output voltage V of the power conversion circuit in real time. o The feedback voltage, and then the given reference voltage V ref The voltage error is obtained by subtracting the feedback voltage from the voltage, where the PI regulator G is located. cv (s) The voltage regulator performs regulation operations based on the voltage error input and outputs a reference current i. Lref Current control loop G close_i (s) Real-time acquisition of inductor current i in power conversion circuit L The feedback current, and then the reference current i Lref The current error is obtained by subtracting the feedback current from the current, and the PI regulator G... ci (s) A modulation reference voltage is generated based on the current error, and the modulation reference voltage is transmitted through the PWM module K. PWM The duty cycle of control switches Q1 and Q2 is generated, thereby regulating the inductor current i flowing through the output inductor L. L .

[0048] In some embodiments, the first feedforward unit is configured to receive a first current signal characterizing the load current of the power conversion circuit, and generate a first voltage compensation signal based on the first current signal. The first feedforward unit has a preset constant amplitude, so that the first voltage compensation signal provides a reference compensation amount in steady state. The first current signal can be the inductor current signal of the power conversion circuit. In steady-state operation, the output current of the power conversion circuit, i.e., the load current, is approximately equal to the current of the output inductor L; therefore, the load current of the power conversion circuit can be calculated using the inductor current.

[0049] Furthermore, the transfer function of the first feedforward unit is G. comp1 =R v1 , where R v1 This is the first preset virtual resistance value.

[0050] In this embodiment, the first feedforward unit is a negative feedforward compensation path related to the load current introduced on the basis of the voltage control loop and the current control loop. That is, feedforward compensation is performed using a virtual resistor to establish a steady-state current sharing rule. According to the requirements of the DC-DC converter system for current sharing accuracy and voltage regulation, the virtual resistor is designed according to the droop control principle, requiring no additional hardware and having low computational complexity. The virtual resistor is the equivalent impedance constructed through the control algorithm. In the low-frequency region, both the voltage regulator and the current regulator use PI regulators, with the integral element integrated inside the voltage regulator and the current regulator. This makes the gain of the closed-loop control loop much greater than one in steady state, and the output impedance approximates the virtual resistor. The current sharing control system exhibits pure resistive characteristics, thereby achieving accurate steady-state current sharing.

[0051] Among them, the first feedforward unit serves as a negative feedforward compensation path, acquiring the load current in real time and calculating it according to the transfer function G. comp1 (s) The corresponding virtual voltage drop is calculated, that is, the corresponding virtual voltage drop is obtained by solving the first preset virtual resistance value. The virtual voltage drop is subtracted from the given reference voltage to obtain the corrected reference voltage, thereby achieving negative compensation of the reference voltage. Therefore, the virtual voltage drop corresponding to the power conversion circuit with a large output current is also larger, which is equivalent to reducing the reference voltage supplied to the voltage control loop, which can suppress the increase of output current and cause the output current to fall back. Similarly, for the power conversion circuit with a small output current, the reference voltage supplied to the voltage control loop is equivalent to increasing, and the output current is naturally increased accordingly. By adjusting the corresponding power conversion circuit with virtual voltage drop, current balance among multiple parallel power conversion circuits is achieved.

[0052] In some embodiments, the second feedforward unit is configured to receive a first current signal and generate a second voltage compensation signal based on the first current signal. The second feedforward unit has a preset frequency characteristic, so that the second voltage compensation signal provides a transient compensation amount related to the rate of change when the load current changes.

[0053] Furthermore, the transfer function of the second feedforward unit is G. comp2 =(R v2 +L v ·s)·ω c / (s+ω c ), where R v2 R is the second preset virtual resistance value. v2 <R v1 Lv To preset the virtual inductance value, ω c s is the cutoff frequency of the preset virtual low-pass filter, and s is the Laplace operator.

[0054] While steady-state current sharing can be addressed in droop control by introducing virtual resistors, system performance during high-frequency dynamic processes is primarily limited by physical hardware parameters. For example, in high-power applications, large-capacity electrolytic capacitors, such as 3760uF, are often used at the output to meet ripple specifications. These 3760uF capacitors can introduce voltage inertia, leading to a lag in the voltage loop response. Furthermore, manufacturing tolerances (typically ±20%) in the output inductor and variations in line impedance can cause physical dynamic output impedance mismatch in the corresponding frequency domain between two parallel power conversion circuits. For instance, during load step transitions, virtual resistors cannot promptly compensate for the impedance differences caused by the inertia of the physical LC filter, resulting in significant transient circulating currents. The second feedforward unit, as a positive feedforward compensation path, can actively cancel the inertia of the physical LC filter through transient compensation. It can solve the dynamic impedance mismatch caused by the deviation of the filter LC parameters during load step, thereby effectively eliminating transient circulating current. It works synergistically with the first feedforward unit to maintain the steady-state current sharing capability of droop control, while also significantly improving the current distribution performance in the dynamic process, achieving the unity of steady-state current sharing and dynamic current sharing, and with low computational complexity.

[0055] The second feedforward unit transmits the load current through the transfer function G. comp2 (s) is converted to a positive feedforward compensation voltage, and the transfer function G comp2 (s) has an inertial cancellation term R v2 +L v ·s and noise suppression term ω c / (s+ω c The inertia cancellation term is the core power source used to achieve low impedance design. Near the resonant frequency, the physical impedance exhibits a significant peak; to suppress this peak, the second feedforward unit needs to generate a compensation signal that cancels out the LC dynamic characteristics. The differential term L... v ·s detects the load current i Load The rate of change of the voltage can significantly increase the duty cycle before and after the voltage control loop response through positive feedforward, thereby strongly suppressing the resonant peak of the physical LC filter and preventing deep voltage drops during load step transitions due to the inductor current's inability to change instantaneously. (Proportional term R) v2 This can compensate for the steady-state gain error in the mid-frequency band, helping the closed-loop impedance curve to smoothly approach the target impedance. The target impedance is a pre-set output impedance specification used to constrain the dynamic fluctuation range of the output voltage under load disturbances. A first-order virtual low-pass filter can solve the differential term L. v The high-frequency gain divergence problem caused by ·s, the differential term Lv The gain of the ·s increases with frequency, while the gain of the low-pass filter decreases with frequency at a rate of -20dB / dec. When cascaded, the gain of the second feedforward unit in the high-frequency range tends to be constant, thus avoiding the infinite amplification of switching noise. Obviously, the first-order low-pass filter in this embodiment can solve the differential term L. v The high-frequency gain divergence problem caused by ·s is addressed by the second feedforward unit in this embodiment, whose transfer function consists of an inertia cancellation term and a noise suppression term. While retaining the inertia cancellation capability, it limits the high-frequency gain to a constant, thus solving the engineering impracticality of pure differential compensation.

[0056] In this embodiment, the second feedforward unit and the first feedforward unit serve as a positive feedforward compensation path and a negative feedforward compensation path, respectively, with the load current i Load The reference voltage is compensated by the second feedforward unit, while the load current i Load The reference voltage is reduced by the first feedforward unit. The second feedforward unit works in conjunction with the first feedforward unit to adopt a dual compensation architecture, which can balance dynamic performance and steady-state accuracy.

[0057] The first feedforward unit and the second feedforward unit can reduce the equivalent output resistance from R at low frequencies. v1 Reduce to R v1 -R v2 This achieves the minimization of voltage drop in steady state without affecting the dynamic response characteristics of the Buck converter system, thus balancing dynamic performance and steady-state accuracy.

[0058] Furthermore, the first and second feedforward units are implemented using digital control algorithms. Without adding extra hardware, the closed-loop output impedance is transformed from a complex second-order characteristic to a pure resistive characteristic over a wide bandwidth by reshaping the output impedance at the control strategy level. This requires no additional hardware and features low computational complexity in the feedforward units, making it easy to implement in engineering. It requires no additional hardware, such as implementation on existing digital controllers (DSPs), making it suitable for low-cost industrial power supply applications.

[0059] In some embodiments, the reference voltage correction unit is configured to negatively superimpose a first voltage compensation signal and positively superimpose a second voltage compensation signal onto the voltage reference signal, and provide the reference voltage after superimposing the first and second voltage compensation signals to the voltage control loop.

[0060] like Figure 2 and Figure 3 As shown, the given reference voltage V ref Subtracting the negative feedforward compensation voltage V1 generated by the first feedforward unit and adding the positive feedforward compensation voltage V2 generated by the second feedforward unit, we obtain the new reference voltage V. ref ′, the new reference voltage Vref The voltage is used as the reference voltage for the voltage control loop.

[0061] As can be seen, the load current is fed back to the input of the reference voltage correction unit via both the negative feedforward compensation path and the positive feedforward compensation path. This reference voltage correction unit also has an input for receiving a given reference voltage V. ref In the reference voltage correction unit, the given reference voltage V is... ref Subtract the negative feedforward compensation voltage V1, add the positive feedforward compensation voltage V2, and obtain the new reference voltage V. ref The output is fed to the voltage control loop for comparison with the feedback voltage.

[0062] The embodiments of this application can effectively counteract the integral effect of the output capacitor C2 through a positive and negative feedforward cooperative mechanism, reshaping the closed-loop output impedance from a complex second-order characteristic to a pure resistive characteristic over a wide bandwidth, and reducing the equivalent output resistance from R v1 Reduce to R v1 Subtract R v2 That is, reduced to R v1 -R v2 This fundamentally eliminates dynamic impedance mismatch and actively counteracts physical inertia.

[0063] like Figure 4 Figure 5 shows a simplified schematic diagram of a dual-parallel Buck converter. Current sharing control according to this embodiment of the application is applied to the dual-parallel Buck converter, and the load step response curve without current sharing control is used for comparison. As shown in Figure 5, the current sharing effect achieved by the current sharing control of this embodiment is better, and the load step response is faster. Experimental results show that the dual-parallel Buck converter system of this embodiment has a steady-state current sharing error of 2.5% under a 10%~90% full-load step, a loading transient current sharing error of 11.3%, and an unloading transient current sharing error of 6.7%. Compared with the scheme without current sharing control, the steady-state current sharing accuracy and transient current sharing performance of this embodiment are significantly improved.

[0064] Referring to Figure 6, which shows the load step response curves of the three-parallel Buck converter using only the virtual resistor droop control scheme and the current sharing control scheme of this embodiment, the case using only the virtual resistor droop control scheme, i.e., only the first feedforward unit, is used. The parameters of each power conversion circuit are the same as those of each power conversion circuit in the dual-parallel Buck converter. Experimental results show that the steady-state current sharing error of the three-parallel Buck converter system of this embodiment is 1.9%, the loaded transient current sharing error is 5.4%, and the unloaded transient current sharing error is 6.9%. Compared with the virtual resistor droop control scheme alone, the steady-state current sharing error of this embodiment is reduced by 64.2%, the loaded transient current sharing error is reduced by 74.6%, and the unloaded transient current sharing error is reduced by 85.7%. It can be seen that the embodiment of this application can balance steady-state and dynamic performance, maintaining the high-precision steady-state current sharing capability of droop control while significantly improving the current distribution performance during dynamic processes.

[0065] Referring to Figure 7, it shows the load step response curves of the three-parallel Buck converter using the current sharing control scheme of this application embodiment under load deviations of 20% for both output inductor and output capacitor. In the three-parallel Buck converter system provided in this application embodiment, tests were conducted on the output inductor and output capacitor with deviations of ±20%. Experimental results show that under a 20% inductor deviation, the steady-state current sharing error is 1.9%, the loaded transient current sharing error is 7.4%, and the unloaded transient current sharing error is 6.9%; under a 20% capacitor deviation, the steady-state current sharing error is 1.9%, the loaded transient current sharing error is 7.4%, and the unloaded transient current sharing error is 6.9%. Clearly, even under significant parameter deviations, this application embodiment maintains excellent current sharing performance, verifying its excellent robustness. Even under ±20% deviations in output inductor and output capacitor parameters, the dynamic impedance characteristics of the parallel converter remain highly consistent, significantly suppressing transient circulating current.

[0066] This application also provides a DC-DC converter system, including a DC-DC converter and a current sharing control system for the DC-DC converter as described above. The DC-DC converter includes at least two power conversion circuits connected in parallel. The current sharing control system includes control circuits of the same number as the power conversion circuits, and the control circuits are connected to the power conversion circuits in a one-to-one correspondence.

[0067] This application embodiment also provides a current sharing control method for a DC-DC converter, applied to the current sharing control system of the DC-DC converter as described above. The current sharing control method mainly includes steps S801 to S806.

[0068] Step S801: Receive a first current signal characterizing the load current of the power conversion circuit, generate a first voltage compensation signal based on the first current signal, and the first feedforward unit has a preset constant amplitude so that the first voltage compensation signal provides a reference compensation amount in steady state.

[0069] Step S802: Receive the first current signal, generate the second voltage compensation signal based on the first current signal, and the second feedforward unit has a preset frequency characteristic so that the second voltage compensation signal provides a transient compensation amount related to the rate of change when the load current changes.

[0070] Step S803: Superimpose the first voltage compensation signal in the negative direction onto the voltage reference signal, and superimpose the second voltage compensation signal in the positive direction;

[0071] Step S804: Generate a current reference signal based on the difference between the reference voltage after superimposing the first voltage compensation signal and the second voltage compensation signal and the output voltage feedback signal of the power conversion circuit;

[0072] Step S805: Generate a switch drive signal based on the difference between the current reference signal and the inductor current feedback signal of the power conversion circuit. The switch drive signal is used to control the power switch of the power conversion circuit.

[0073] Further, in step S801, generating the first voltage compensation signal based on the first current signal may include: transforming the first current signal through the transfer function of the first feedforward unit to generate the first voltage compensation signal, wherein the transfer function of the first feedforward unit is G. comp1 =R v1 , where R v1 The first preset virtual resistance value is used. Furthermore, in step S802, generating the second voltage compensation signal based on the first current signal may include: transforming the first current signal through the transfer function of the second feedforward unit to generate the second voltage compensation signal, where the transfer function of the second feedforward unit is G. comp2 =(R v2 +L v ·s)·ω c / (s+ω c ), where R v2 R is the second preset virtual resistance value. v2 <R v1 L v To preset the virtual inductance value, ω c s is the cutoff frequency of the preset virtual low-pass filter, and s is the Laplace operator.

[0074] For details regarding the implementation process of each step in the above embodiments, please refer to the implementation process of the corresponding functions and roles in the above system embodiments. These details will not be elaborated here.

[0075] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0076] It should be noted that the method embodiments, television terminal embodiments, and computer-readable storage medium embodiments provided in this application belong to the same concept; the technical features in the technical solutions described in each embodiment can be arbitrarily combined without conflict.

[0077] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of this application and do not limit the scope of protection of this patent application.

Claims

1. A current sharing control system for a DC-DC converter, characterized in that, The DC-DC converter includes at least two power conversion circuits connected in parallel, and the current sharing control system includes control circuits connected to each of the power conversion circuits in a one-to-one correspondence; each control circuit includes: A voltage control loop configured to generate a current reference signal based on the difference between a voltage reference signal and the output voltage feedback signal of the power conversion circuit; A current control loop is configured to generate a switch drive signal based on the difference between the current reference signal and the inductor current feedback signal of the power conversion circuit, the switch drive signal being used to control the power switch of the power conversion circuit. A first feedforward unit is configured to receive a first current signal characterizing the load current of the power conversion circuit, and generate a first voltage compensation signal based on the first current signal. The first feedforward unit has a preset constant amplitude, so that the first voltage compensation signal provides a reference compensation amount in steady state. The second feedforward unit is configured to receive the first current signal and generate a second voltage compensation signal based on the first current signal. The second feedforward unit has a preset frequency characteristic so that the second voltage compensation signal provides a transient compensation amount related to the rate of change when the load current changes. A reference voltage correction unit is configured to negatively superimpose the first voltage compensation signal and positively superimpose the second voltage compensation signal onto the voltage reference signal, and provide the reference voltage after superimposing the first voltage compensation signal and the second voltage compensation signal to the voltage control loop.

2. The flow sharing control system according to claim 1, characterized in that, The DC-DC converter includes a Buck converter.

3. The flow sharing control system according to claim 1, characterized in that, The first current signal is the inductor current signal of the power conversion circuit.

4. The flow sharing control system according to claim 1, characterized in that, The transfer function of the first feedforward unit is G comp1 =R v1 , where R v1 This is the first preset virtual resistance value.

5. The flow sharing control system according to claim 4, characterized in that, The transfer function of the second feedforward unit is G comp2 =(R v2 +L v ·s)·ω c / (s+ω c ), where R v2 R is the second preset virtual resistance value. v2 <R v1 L v To preset the virtual inductance value, ω c s is the cutoff frequency of the preset virtual low-pass filter, and s is the Laplace operator.

6. The flow sharing control system according to claim 1, characterized in that, The first feedforward unit and the second feedforward unit are implemented using a digital control algorithm.

7. The flow sharing control system according to claim 1, characterized in that, The voltage control loop includes a voltage regulator, and the current control loop includes a current regulator. Both the voltage regulator and the current regulator are proportional-integral regulators.

8. A DC-DC converter system, characterized in that, The system includes a DC-DC converter and a current sharing control system for the DC-DC converter as described in any one of claims 1 to 7, wherein the DC-DC converter includes at least two power conversion circuits connected in parallel, and the current sharing control system includes a number of control circuits equal to the number of power conversion circuits, wherein the control circuits are connected in a one-to-one correspondence with the power conversion circuits.

9. A current sharing control method for a DC-DC converter, characterized in that, The current sharing control system applied to the DC-DC converter as described in any one of claims 1 to 7, the current sharing control method comprising: The first current signal characterizing the load current of the power conversion circuit is received, and a first voltage compensation signal is generated based on the first current signal. The first feedforward unit has a preset constant amplitude, so that the first voltage compensation signal provides a reference compensation amount in steady state. The first current signal is received, and a second voltage compensation signal is generated based on the first current signal. The second feedforward unit has a preset frequency characteristic, so that the second voltage compensation signal provides a transient compensation amount related to the rate of change when the load current changes. The first voltage compensation signal is superimposed negatively onto the voltage reference signal, and the second voltage compensation signal is superimposed positively. A current reference signal is generated based on the difference between the reference voltage after superimposing the first voltage compensation signal and the second voltage compensation signal and the output voltage feedback signal of the power conversion circuit. A switch drive signal is generated based on the difference between the current reference signal and the inductor current feedback signal of the power conversion circuit. The switch drive signal is used to control the power switch of the power conversion circuit.

10. The flow sharing control method according to claim 9, characterized in that, The step of generating a first voltage compensation signal based on the first current signal includes: The first current signal is transformed by the transfer function of the first feedforward unit to generate the first voltage compensation signal. The transfer function of the first feedforward unit is G. comp1 =R v1 , where R v1 The first preset virtual resistance value; and, The step of generating a second voltage compensation signal based on the first current signal includes: The first current signal is transformed by the transfer function of the second feedforward unit to generate the second voltage compensation signal. The transfer function of the second feedforward unit is G. comp2 =(R v2 +L v ·s)·ω c / (s+ω c ), where R v2 R is the second preset virtual resistance value. v2 <R v1 L v To preset the virtual inductance value, ω c s is the cutoff frequency of the preset virtual low-pass filter, and s is the Laplace operator.

Images