Interleaved BUCK output current sharing control circuit with isolated DC output

Abstract

This utility model discloses an interleaved BUCK output current sharing control circuit with isolated DC output, belonging to the field of BUCK output. It includes a DC source VD1, two BUCK topology circuits, and two isolated DC output circuits. The DC source VD1 is connected to both BUCK topology circuits, and each BUCK topology circuit is connected to one of the two isolated DC output circuits. The two BUCK topology circuits include an A-phase BUCK topology circuit and a B-phase BUCK topology circuit. The two BUCK topology circuits also include an A-phase isolated DC output circuit and a B-phase isolated DC output circuit. This utility model enables adaptive fan speed adjustment based on load changes; the larger the load, the higher the speed, without requiring additional software control. It reduces output current ripple and the size of the output filter capacitor. Simultaneously, it improves the stress on the switching transistor, resulting in more uniform heat distribution and increased system reliability.

Description

Technical Field

[0001] This utility model relates to the field of BUCK output, specifically an interleaved BUCK output current sharing control circuit with isolated DC output. Background Technology

[0002] A BUCK circuit is a step-down DC-DC converter that achieves voltage conversion through the periodic switching of a switching device. Its core structure consists of a switching transistor, an inductor, a freewheeling diode, and a filter capacitor. It utilizes the energy storage and release principle of the inductor to achieve the voltage reduction function. The core function of the BUCK output circuit is to maintain a stable output voltage, achieving voltage conversion through inductor energy storage and capacitor filtering. The output voltage is adjusted by controlling the duty cycle (on-time ratio) of the switching transistor. When the input voltage changes, adjusting the duty cycle maintains a stable output voltage. When the switching transistor is on, the input voltage supplies power to the capacitor and load through the inductor, while simultaneously storing energy. When the switching transistor is off, the inductor discharges through the freewheeling diode, maintaining a stable load voltage. At this time, the capacitor continues to supply power to the load and stores remaining energy.

[0003] Traditional BUCK circuits, when connected in parallel, suffer from poor current sharing due to differences in hardware parameters. This results in uneven heating of switching transistors and magnetic components, large output ripple, and reduced system reliability. Furthermore, the lack of an isolation auxiliary winding prevents the achievement of isolated power supply. Utility Model Content

[0004] To address some existing problems, the purpose of this invention is to provide an interleaved BUCK output current sharing control circuit with isolated DC output, so as to solve the problem that isolated power supply cannot be achieved without an isolation auxiliary winding.

[0005] To achieve the above objectives, this utility model provides the following technical solution: An interleaved BUCK output current sharing control circuit with isolated DC output includes a DC source VD1, two BUCK topology circuits, and two isolated DC output circuits. The DC source VD1 is connected to both BUCK topology circuits, and each BUCK topology circuit is connected to one of the two isolated DC output circuits. The two BUCK topology circuits include an A-phase BUCK topology circuit and a B-phase BUCK topology circuit. The two BUCK topology circuits also include an A-phase isolated DC output circuit and a B-phase isolated DC output circuit.

[0006] As a further embodiment of this utility model: the A-phase BUCK topology circuit includes a switch Q1, a diode D1, the primary side of a transformer T1, a current transformer CT1, a capacitor C1, and a resistor R1.

[0007] As a further embodiment of this utility model: the input terminal of the switch Q1 is connected to the input terminal of the switch Q2 and the positive terminal of the DC source; the output terminal of the switch Q1 is connected to the non-same-name terminal of the primary winding of the transformer T1 and the negative terminal of the diode D1; the negative terminal of the diode D1 is connected to the output terminal of the switch Q1 and the non-same-name terminal of the primary winding of the transformer T1; the non-same-name terminal of the primary winding of the transformer T1 is connected to the output terminal of the switch Q1 and the negative terminal of the diode D1; the same-name terminal of the primary winding of the transformer T1 is connected to the input terminal of the current transformer CT1; the output terminal of the current transformer CT1 is connected to the common terminal of the capacitor C1 and the resistor R1; the other end of the capacitor C1 is connected to GND1; and the other end of the resistor R1 is connected to GND1.

[0008] As a further embodiment of this invention, the positive terminal of diode D1 is connected to GND1.

[0009] As a further embodiment of this utility model: the A-phase isolated DC output circuit includes the secondary winding of transformer T1, diode D2, capacitor C2, resistor R2 and fan F1.

[0010] As a further embodiment of this utility model: the same-name terminal of the secondary winding of the transformer T1 is connected to the positive terminal of the diode D2, and the negative terminal of the diode D2 is connected to one end of the capacitor C2, one end of the resistor R2, and the positive terminal of the fan F1; the non-same-name terminal of the transformer T1, the capacitor C2, the resistor R2, and the negative terminal of the fan F1 are connected to GND2.

[0011] As a further embodiment of this utility model: the B-phase BUCK topology circuit includes a switch Q2, a diode D3, the primary side of a transformer T2, a current transformer CT2, a capacitor C4, and a resistor R4.

[0012] As a further embodiment of this utility model: the input terminal of the switch Q2 is connected to the input terminal of the switch Q1 and the positive terminal of the DC source; the output terminal of the switch Q2 is connected to the non-same-name terminal of the primary winding of the transformer T2 and the negative terminal of the diode D3; the negative terminal of the diode D3 is connected to the output terminal of the switch Q2 and the non-same-name terminal of the primary winding of the transformer T2; the non-same-name terminal of the primary winding of the transformer T2 is connected to the output terminal of the switch Q2 and the negative terminal of the diode D3; the same-name terminal of the primary winding of the transformer T2 is connected to the input terminal of the current transformer CT2; the output terminal of the current transformer CT2 is connected to the common terminal of the capacitor C3 and the resistor R3; the other end of the capacitor C3 is connected to GND1; the other end of the resistor R3 is connected to GND1; and the positive terminal of the diode D3 is connected to GND1.

[0013] As a further embodiment of this utility model: the B-phase isolated DC output circuit includes the secondary winding of transformer T2, diode D4, capacitor C4, resistor R4 and fan F2.

[0014] As a further embodiment of this utility model: the same-name terminal of the secondary winding of the transformer T2 is connected to the positive terminal of the diode D4, the negative terminal of the diode D4 is connected to one end of the capacitor C4, one end of the resistor R4, and the positive terminal of the fan F2; the non-same-name terminal of the transformer T2, the capacitor C4, the resistor R4, and the negative terminal of the fan F2 are connected to GND2.

[0015] Compared with the prior art, the beneficial effects of this utility model are: This invention enables adaptive fan speed adjustment that follows load changes; the higher the load, the higher the speed, without requiring additional software control. The PI controller parameters Kp and Ki are intelligently tuned using the PSO algorithm, reducing manual adjustments and improving the system's dynamic response and stability. Through 180-degree phase-shifted interleaved parallel BUCK current sharing control, output current ripple is reduced, and the size of the output filter capacitor is decreased. Simultaneously, it improves the stress on the switching transistors, resulting in more uniform heat distribution and increased system reliability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an interleaved BUCK output current sharing control circuit with isolated DC output.

[0017] Figure 2 This is a voltage V speed control curve for the fan in an interleaved BUCK output current sharing control circuit with isolated DC output.

[0018] Figure 3 This is a basic schematic diagram of the current sharing control in an interleaved BUCK output current sharing control circuit with isolated DC output.

[0019] Figure 4 The steps are for a control method in an interleaved BUCK output current sharing control circuit with isolated DC output. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0022] Please see Figure 1-4 An interleaved BUCK output current sharing control circuit with isolated DC output includes a DC source VD1, two BUCK topology circuits, and two isolated DC output circuits. The DC source VD1 is connected to two BUCK topology circuits, and the two BUCK topology circuits are respectively connected to two isolated DC output circuits. The two-way BUCK topology circuit includes an A-phase BUCK topology circuit and a B-phase BUCK topology circuit; The two-way BUCK topology circuit includes an A-phase isolated DC output circuit and a B-phase isolated DC output circuit.

[0023] This invention includes a DC power source VD1, two BUCK topology circuits, and two isolated DC output circuits. The two BUCK circuits with isolated DC outputs are connected in parallel and phase-shifted by 180° to reduce output current ripple. By specifying the minimum load on the BUCK circuit, a minimum isolated DC voltage of 8V can be obtained to ensure fan power supply. As the load on the BUCK circuit increases, the isolated DC voltage continuously rises until it reaches 12V, achieving the fan's maximum speed, thus realizing the function of adaptively adjusting the fan speed according to the load.

[0024] The parameters Kp and Ki of the PI controller of this invention are intelligently tuned by the PSO algorithm, reducing manual adjustment and improving the dynamic response and stability of the system.

[0025] See the interleaved parallel BUCK circuit with isolated DC output. Figure 1 It consists of two identical BUCK circuits with isolated DC output connected in parallel on the input and output sides, respectively. For ease of subsequent description, it is divided into two phases, A and B. The phase difference between A and B is always maintained at 180°, effectively reducing the output current ripple.

[0026] The A-phase BUCK topology circuit includes a switch Q1, a diode D1, the primary winding of a transformer T1, a current transformer CT1, a capacitor C1, and a resistor R1. The input terminal of the switch Q1 is connected to the input terminal of the switch Q2 and the positive terminal of the DC source. The output terminal of the switch Q1 is connected to the non-same-name terminal of the primary winding of the transformer T1 and the negative terminal of the diode D1. The negative terminal of the diode D1 is connected to the output terminal of the switch Q1 and the non-same-name terminal of the primary winding of the transformer T1, and the positive terminal of the diode D1 is connected to GND1. The non-same-name terminal of the primary winding of the transformer T1 is connected to the output terminal of the switch Q1 and the negative terminal of the diode D1. The same-name terminal of the primary winding of the transformer T1 is connected to the input terminal of the current transformer CT1. The output terminal of the current transformer CT1 is connected to the common terminal of the capacitor C1 and the resistor R1. The other end of the capacitor C1 is connected to GND1, and the other end of the resistor R1 is connected to GND1. The A-phase isolated DC output circuit includes the secondary winding of transformer T1, diode D2, capacitor C2, resistor R2, and fan F1; the same-name terminal of the secondary winding of transformer T1 is connected to the positive terminal of diode D2, and the negative terminal of diode D2 is connected to one end of capacitor C2, one end of resistor R2, and the positive terminal of fan F1; the non-same-name terminal of transformer T1, capacitor C2, resistor R2, and the negative terminal of fan F1 are connected to GND2; The B-phase BUCK topology circuit includes a switch Q2, a diode D3, the primary winding of transformer T2, a current transformer CT2, a capacitor C4, and a resistor R4. The input terminal of switch Q2 is connected to the input terminal of switch Q1 and the positive terminal of the DC source. The output terminal of switch Q2 is connected to the non-same-name terminal of the primary winding of transformer T2 and the negative terminal of diode D3. The negative terminal of diode D3 is connected to the output terminal of switch Q2 and the non-same-name terminal of the primary winding of transformer T2, while the positive terminal of diode D3 is connected to GND1. The non-same-name terminal of the primary winding of transformer T2 is connected to the output terminal of switch Q2 and the negative terminal of diode D3. The same-name terminal of the primary winding of transformer T2 is connected to the input terminal of current transformer CT2. The output terminal of current transformer CT2 is connected to the common terminal of capacitor C3 and resistor R3. The other end of capacitor C3 and resistor R3 are both connected to GND1. The B-phase isolated DC output circuit includes the secondary winding of transformer T2, diode D4, capacitor C4, resistor R4, and fan F2; the same-name terminal of the secondary winding of transformer T2 is connected to the positive terminal of diode D4, and the negative terminal of diode D4 is connected to one end of capacitor C4, one end of resistor R4, and the positive terminal of fan F2; the non-same-name terminal of transformer T2, capacitor C4, resistor R4, and the negative terminal of fan F2 are connected to GND2. Assuming the interleaved parallel BUCK with isolated DC output operates under ideal conditions, neglecting differences between components, parasitic effects of the components themselves, and conduction losses, the working principle in this operating mode will be explained in detail. Within this cycle, the main operating timing is divided into two states.

[0027] Modal 1: When phase A switch Q1 is turned on, the DC source charges the primary winding of transformer T1 and output capacitor C1 through Q1, while simultaneously supplying power to load R1. The secondary winding of transformer T1 stores energy through inductance, capacitor C2 discharges into resistor R2, and simultaneously supplies power to fan F1.

[0028] When phase B switch Q2 is off, the primary winding of transformer T2 acts as a current source to charge capacitor C3, and simultaneously supplies power to resistor R3 and the load. The secondary winding of transformer T2 acts as a current source to charge capacitor C2, and simultaneously supplies power to resistor R2 and fan F1.

[0029] Mode 2: When phase A switch Q1 is off, the primary winding of transformer T1 acts as a current source to charge capacitor C1, and simultaneously supplies power to resistor R1 and the load. The secondary winding of transformer T1 acts as a current source to charge capacitor C4, and simultaneously supplies power to resistor R4 and fan F2.

[0030] When phase B switch Q2 is turned on, the DC source charges the primary winding of transformer T2 and output capacitor C3 through Q2, while simultaneously supplying power to load R3. The secondary winding of transformer T2 stores energy through its inductance, capacitor C4 discharges into resistor R4, and simultaneously supplies power to fan F2.

[0031] Figure 2 This is a voltage speed control curve for the fan. Within the fan's normal power supply range, the higher the fan voltage, the higher the fan speed.

[0032] Resistors R2 and R4 determine the minimum load for the isolated DC output. Adjusting resistors R2 and R4 determines the minimum supply voltage of fans F1 and F2 to 8V. At the same time, it determines the maximum load of the isolated DC output when the load is full. The inductance and turns ratio of transformers T1 and T2 can be adjusted to set the maximum operating voltage of fans F1 and F2 to 12V when the load is full. According to the fan voltage speed control diagram, 8V corresponds to a fan speed of 2800 RPM, and 12V corresponds to a speed of 7500 RPM. Therefore, when the load is between no-load and full-load, the supply voltage of fans F1 and F2 is between 8V and 12V, and the fan speed is between 2800 and 7500 RPM, realizing the function of adaptive adjustment of fan speed as the load increases.

[0033] Figure 3 This is a basic schematic diagram of current sharing control based on an interleaved parallel BUCK converter with isolated DC output.

[0034] PSO algorithm:

[0035] V is the velocity of the i-th particle in the k-th iteration; x is the position of the i-th particle in the k-th iteration; w is the inertia weight with a value of 0.8; c1 and c2 are learning factors with a value of 2; r1 and r2 are random numbers in [0, 1]; pBest is the individual optimal position; gBest is the global optimal position.

[0036] I TAE Evaluation indicators:

[0037] This invention employs current loop control, with automatic PI parameter tuning via the PSO algorithm. The two BUCK currents are adjusted by two P controllers, with each given current being half of the target current. The two PI controllers automatically achieve current sharing control.

[0038] In this process, the parameters Kp and Ki of the PI controller are intelligently tuned by the PSO algorithm. Specifically, an error value is input into the PSO algorithm, and this error is used to calculate the fitness function I in the algorithm. TAE I TAE This is the PID evaluation metric; the smaller the metric, the better the PID parameter tuning performance. The algorithm will transiently adjust the Kp and Ki parameters based on the error value. If the current fitness function value is better than the previous one, the Kp and Ki parameters are updated; otherwise, they remain unchanged.

[0039] Figure 4 Steps for current sharing control method based on interleaved parallel BUCK converter with isolated DC output

[0040] Step 1: Using traditional parameter tuning methods, roughly estimate the parameter value range [a, b]. If the number of particles is N, then the particle swarm initially has N two-dimensional particles Xi = (x...). ip ,x ii Kp and Ki are the positions of each particle.

[0041] Step 2: Select I TAE The evaluation index is the particle swarm fitness function. The smaller the value of this index, the better the PI parameter tuning effect.

[0042] Step 3: Set initial values ​​for Kp and Ki, calculate using the fitness function, compare fitness values, record the current best particle in the individual and the best particle in the group, and update particle velocity and position.

[0043] Step 4: Output the current optimal value to the PI controller to calculate the error value for the next step.

[0044] Step 5: Input the error value into the PSO algorithm for the next iteration.

[0045] Step 6: The algorithm stops updating when the number of iterations reaches the maximum value.

[0046] This invention enables adaptive fan speed adjustment that follows load changes; the higher the load, the higher the speed, without requiring additional software control. The PI controller parameters Kp and Ki are intelligently tuned using the PSO algorithm, reducing manual adjustments and improving the system's dynamic response and stability. Through 180-degree phase-shifted interleaved parallel BUCK current sharing control, output current ripple is reduced, and the size of the output filter capacitor is decreased. Simultaneously, it improves the stress on the switching transistors, resulting in more uniform heat distribution and increased system reliability. This invention, through 180-degree phase shifting, effectively reduces output current ripple, lowers EMI risks, improves efficiency and system reliability, and provides adaptive fan speed adjustment based on load changes.

[0047] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects; the scope of this invention is defined by the appended claims rather than the foregoing description; and thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution; this narrative style is merely for clarity; those skilled in the art should consider the specification as a whole; the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An interleaved BUCK output current sharing control circuit with isolated DC output, characterized in that, It includes a DC source VD1, two BUCK topology circuits, and two isolated DC output circuits; the DC source VD1 is connected to both BUCK topology circuits, and the two BUCK topology circuits are respectively connected to the two isolated DC output circuits; the two BUCK topology circuits include an A-phase BUCK topology circuit and a B-phase BUCK topology circuit; the two BUCK topology circuits include an A-phase isolated DC output circuit and a B-phase isolated DC output circuit.

2. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 1, characterized in that, The A-phase BUCK topology circuit includes a switch Q1, a diode D1, the primary side of a transformer T1, a current transformer CT1, a capacitor C1, and a resistor R1.

3. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 2, characterized in that, The input terminal of the switch Q1 is connected to the input terminal of the switch Q2 and the positive terminal of the DC source. The output terminal of the switch Q1 is connected to the non-same-name terminal of the primary winding of the transformer T1 and the negative terminal of the diode D1. The negative terminal of the diode D1 is connected to the output terminal of the switch Q1 and the non-same-name terminal of the primary winding of the transformer T1. The non-same-name terminal of the primary winding of the transformer T1 is connected to the output terminal of the switch Q1 and the negative terminal of the diode D1. The same-name terminal of the primary winding of the transformer T1 is connected to the input terminal of the current transformer CT1. The output terminal of the current transformer CT1 is connected to the common terminal of the capacitor C1 and the resistor R1. The other end of the capacitor C1 is connected to GND1, and the other end of the resistor R1 is connected to GND1.

4. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 3, characterized in that, The positive terminal of diode D1 is connected to GND1.

5. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 4, characterized in that, The A-phase isolated DC output circuit includes the secondary winding of transformer T1, diode D2, capacitor C2, resistor R2, and fan F1.

6. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 5, characterized in that, The same-name terminal of the secondary winding of transformer T1 is connected to the positive terminal of diode D2, and the negative terminal of diode D2 is connected to one end of capacitor C2, one end of resistor R2, and the positive terminal of fan F1; the non-same-name terminal of transformer T1, capacitor C2, resistor R2, and the negative terminal of fan F1 are connected to GND2.

7. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 6, characterized in that, The B-phase BUCK topology circuit includes a switch Q2, a diode D3, the primary side of a transformer T2, a current transformer CT2, a capacitor C4, and a resistor R4.

8. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 7, characterized in that, The input terminal of the switch Q2 is connected to the input terminal of the switch Q1 and the positive terminal of the DC source. The output terminal of the switch Q2 is connected to the non-same-name terminal of the primary winding of transformer T2 and the negative terminal of diode D3. The negative terminal of diode D3 is connected to the output terminal of switch Q2 and the non-same-name terminal of the primary winding of transformer T2. The non-same-name terminal of the primary winding of transformer T2 is connected to the output terminal of switch Q2 and the negative terminal of diode D3. The same-name terminal of the primary winding of transformer T2 is connected to the input terminal of current transformer CT2. The output terminal of current transformer CT2 is connected to the common terminal of capacitor C3 and resistor R3. The other end of capacitor C3 is connected to GND1, and the other end of resistor R3 is connected to GND1. The positive terminal of diode D3 is connected to GND1.

9. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 8, characterized in that, The B-phase isolated DC output circuit includes the secondary winding of transformer T2, diode D4, capacitor C4, resistor R4, and fan F2.

10. The interleaved BUCK output current sharing control circuit with isolated DC output according to claim 9, characterized in that, The same-name terminal of the secondary winding of transformer T2 is connected to the positive terminal of diode D4, and the negative terminal of diode D4 is connected to one end of capacitor C4, one end of resistor R4, and the positive terminal of fan F2; the non-same-name terminal of transformer T2, capacitor C4, resistor R4, and the negative terminal of fan F2 are connected to GND2.

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