Bidirectional wide-range DCDC module and control method thereof

Abstract

The invention belongs to the technical field of battery charging and discharging management, and particularly provides a bidirectional wide-range DCDC module and a control method thereof. Comprising a first isolation DCDC conversion circuit, a second isolation DCDC conversion circuit, an input capacitor C1, an input capacitor C2, an input soft start circuit, an output capacitor C3, an output capacitor C4, a series-parallel adjustment switch S1, a series-parallel adjustment switch S2, a series-parallel adjustment switch S3, an output soft start circuit, a microcontroller and a power supply for supplying power to the whole module. Starting impact current caused by a thin-film capacitor when multiple modules are connected in parallel is eliminated, power at the two ends of the converter can be accurately controlled, model selection of power semiconductor devices is facilitated, cost is reduced, transient current overshoot when a constant-voltage state is switched to a constant-current state is eliminated through a voltage and current double-closed-loop control method, switching devices are protected, error protection is avoided, and reliability of the converter is improved. According to the voltage-sharing and current-sharing control method, voltage and current balancing of the two DCDC converters in the module is achieved, the overvoltage or overcurrent phenomenon of one module is avoided, an output capacitor and a switching device are protected, and the module works stably and reliably.

Description

Technical Field

[0001] The invention belongs to the technical field of battery charge and discharge management, and in particular relates to a bidirectional wide-range DCDC module and a control method thereof. Background Art

[0002] In V2G charging piles, bidirectional on-board chargers and emergency battery charging and discharging systems, bidirectional wide-range DCDC modules play a vital role, responsible for efficient and stable energy transmission between external power sources and batteries in external discharge systems. However, the traditional bidirectional wide-range DCDC module design has exposed a series of technical problems in response to the high requirements of modern emergency power supply systems.

[0003] In traditional designs, in order to filter out high-frequency interference, film capacitors are often placed at the input and output ports of the module. Although this approach is effective, as the number of modules connected in parallel increases, the capacitance of the film capacitor will increase accordingly, resulting in excessive impact current at startup, which not only poses a threat to the stability of the system, but may also damage other components in the circuit. Secondly, although the output side of the traditional bidirectional wide-range DCDC module can be switched between series and parallel modes to achieve input and output in a wide voltage range, in actual applications, only the current on this side is often sampled to control the charging and discharging power of the battery. Although this approach simplifies the control system, it cannot accurately control the power on the other side (i.e., the input side or another parallel / series module), resulting in the inability to accurately execute the power instructions of the energy scheduling system when connected to complex energy management systems such as light storage and charging systems.

[0004] In addition, the traditional bidirectional wide-range DCDC module has a large output current under low-voltage and high-power working conditions, which places extremely high demands on the selection of semiconductor power switch devices, which not only increases the cost but also limits the application scope of the module. Furthermore, when the bidirectional wide-range DCDC module switches between the constant voltage control and constant current control functions, it is easy to generate instantaneous current overshoot due to the switching between the two separate control loops, which may trigger the overcurrent protection mechanism and even damage the device, affecting the reliability and safety of the system. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a bidirectional wide-range DCDC module and a control method thereof to solve the above-mentioned technical problems.

[0006] In a first aspect, the present invention provides a bidirectional wide-range DCDC module, comprising a first isolated DCDC conversion circuit, a second isolated DCDC conversion circuit, an input capacitor C1, an input capacitor C2, an input soft-start circuit, an output capacitor C3, an output capacitor C4, a series-parallel regulating switch S1, a series-parallel regulating switch S2, a series-parallel regulating switch S3, an output soft-start circuit, a microcontroller, and a power supply for powering the entire module; The first input end of the first isolated DCDC conversion circuit and the first input end of the second isolated DCDC conversion circuit are both connected to the first end of the capacitor C1 and the first output end of the input soft-start circuit, the second input end of the first isolated DCDC conversion circuit and the second input end of the second isolated DCDC conversion circuit are both connected to the first end of the capacitor C2 and the second output end of the input soft-start circuit, the second end of the capacitor C1 is connected to the second end of the capacitor C2, the first input end and the second input end of the input soft-start circuit serve as input ports of the bidirectional wide-range DCDC module, and the input port of the bidirectional wide-range DCDC module is connected to an external power supply; The first output end of the first isolated DCDC conversion circuit is connected to the first end of the output capacitor C3, the first end of the series-parallel regulating switch S2 and the first input end of the output soft-start circuit, the second end of the output capacitor C3 is connected to the second output end of the first isolated DCDC conversion circuit, the second output end of the first isolated DCDC conversion circuit is connected to the first output end of the second isolated DCDC conversion circuit through the series-parallel regulating switch S1, the first output end of the second isolated DCDC conversion circuit is connected to the first end of the output capacitor C4 and the second end of the series-parallel regulating switch S2, the second end of the output capacitor C4 is connected to the second output end of the second isolated DCDC conversion circuit, the second output end of the second isolated DCDC conversion circuit is connected to the first end of the series-parallel regulating switch S3 and the second input end of the output soft-start circuit, the second end of the series-parallel regulating switch S3 is connected to the second output end of the first isolated DCDC conversion circuit, the first output end and the second output end of the output soft-start circuit serve as output ports of the bidirectional wide-range DCDC module, and the output port of the bidirectional wide-range DCDC module is connected to the battery in the external charging and discharging system; The first isolated DCDC conversion circuit, the second isolated DCDC conversion circuit, the input soft start circuit, the series-parallel regulating switch S1, the series-parallel regulating switch S2, the series-parallel regulating switch S3 and the output soft start circuit are all connected to the microcontroller control.

[0007] A further improvement of the technical solution is that the first isolated DCDC conversion circuit includes MOS transistor Q1, MOS transistor Q2, MOS transistor Q3, MOS transistor Q4, capacitor C5, inductor L1, transformer T1, capacitor C6, MOS transistor Q5, MOS transistor Q6, MOS transistor Q7, MOS transistor Q8, MOS transistor Q9, MOS transistor Q10, MOS transistor Q11 and MOS transistor Q12; The drain of the MOS transistor Q1 and the drain of the MOS transistor Q2 are both connected to the first end of the input capacitor C1, the source of the MOS transistor Q1 is connected to the drain of the MOS transistor Q3 and the first end of the primary coil of the transformer T1, the source of the MOS transistor Q2 is connected to the drain of the MOS transistor Q4 and the first end of the capacitor C5, the second end of the capacitor C5 is connected to the second end of the primary coil of the transformer T1 through the inductor L1, and the source of the MOS transistor Q3 and the source of the MOS transistor Q4 are both connected to the first end of the input capacitor C2; A first end of the secondary coil of the transformer T1 is connected to the source of the MOS transistor Q5, the source of the MOS transistor Q6, the drain of the MOS transistor Q7, and the drain of the MOS transistor Q8 through the capacitor C6, a second end of the secondary coil of the transformer T1 is connected to the source of the MOS transistor Q9, the source of the MOS transistor Q10, the drain of the MOS transistor Q11, and the drain of the MOS transistor Q12, the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, the drain of the MOS transistor Q9, and the drain of the MOS transistor Q10 are all connected to the first end of the output capacitor C3, and the source of the MOS transistor Q7, the source of the MOS transistor Q8, the source of the MOS transistor Q11, and the source of the MOS transistor Q12 are all connected to the second end of the output capacitor C3.

[0008] A further improvement of the technical solution is that the second isolated DCDC conversion circuit includes MOS tube Q13, MOS tube Q14, MOS tube Q15, MOS tube Q16, capacitor C7, inductor L2, transformer T2, capacitor C8, MOS tube Q17, MOS tube Q18, MOS tube Q19, MOS tube Q20, MOS tube Q21, MOS tube Q22, MOS tube Q23 and MOS tube Q24; The drain of the MOS transistor Q13 and the drain of the MOS transistor Q14 are both connected to the first end of the input capacitor C1, the source of the MOS transistor Q13 is connected to the drain of the MOS transistor Q15 and the first end of the primary coil of the transformer T2, the source of the MOS transistor Q14 is connected to the drain of the MOS transistor Q16 and the first end of the capacitor C7, the second end of the capacitor C7 is connected to the second end of the primary coil of the transformer T2 through the inductor L2, and the source of the MOS transistor Q15 and the source of the MOS transistor Q16 are both connected to the first end of the input capacitor C2; A first end of the secondary coil of the transformer T2 is connected to the source of the MOS transistor Q17, the source of the MOS transistor Q18, the drain of the MOS transistor Q19, and the drain of the MOS transistor Q20 through the capacitor C8, a second end of the secondary coil of the transformer T2 is connected to the source of the MOS transistor Q21, the source of the MOS transistor Q22, the drain of the MOS transistor Q23, and the drain of the MOS transistor Q24, the drain of the MOS transistor Q17, the drain of the MOS transistor Q18, the drain of the MOS transistor Q21, and the drain of the MOS transistor Q22 are all connected to the first end of the output capacitor C4, and the source of the MOS transistor Q19, the source of the MOS transistor Q20, the source of the MOS transistor Q23, and the source of the MOS transistor Q24 are all connected to the second end of the output capacitor C4.

[0009] A further improvement of the technical solution also includes a first current sampler R1, a second current sampler R2 and a third current sampler R3, wherein a first end of the first current sampler R1 is connected to an input end of an external device, a second end of the first current sampler R1 is connected to a first end of an input capacitor C2, a first end of the second current sampler R2 is connected to a source of a MOS tube Q12, a second end of the second current sampler R2 is connected to a second end of an output capacitor C3, a first end of the third current sampler R3 is connected to a source of a MOS tube Q24, and a second end of the third current sampler R3 is connected to a second end of an output capacitor C4.

[0010] A further improvement of the technical solution is that it also includes a first voltage sampler, a second voltage sampler and a third voltage sampler, wherein the first end of the first voltage sampler is connected to the first end of the capacitor C1, the second end of the first voltage sampler is connected to the first end of the first current sampler R1, the first end of the second voltage sampler is connected to the first end of the series-parallel regulation switch S2, the second end of the second voltage sampler is connected to the second end of the output capacitor C3, the first end of the third voltage sampler is connected to the first end of the output capacitor C4, and the second end of the third voltage sampler is connected to the first end of the series-parallel regulation switch S3.

[0011] A further improvement of the technical solution is that the input soft-start circuit includes a start switch S4, a start switch S5, a resistor R4 and a film capacitor Cfin, the first end of the start switch S4 and the first end of the start switch S5 are both connected to the first end of the external DC power supply, the second end of the start switch S4 is connected to the first end of the resistor R4, the first end of the film capacitor Cfin and the first end of the input capacitor C1, the second end of the start switch S5 is connected to the second end of the resistor R4, and the second end of the film capacitor Cfin is connected to the first end of the input capacitor C2 and the second end of the external DC power supply.

[0012] A further improvement of the technical solution is that the output soft-start circuit includes a start switch S6, a start switch S7, a resistor R5 and a film capacitor Cfo, the first end of the start switch S6 and the first end of the start switch S7 are both connected to the first end of the series-parallel regulation switch S2 and the first end of the film capacitor Cfo, the second end of the start switch S6 is connected to the first end of the resistor R5 and the first end of the external device, the second end of the start switch S7 is connected to the second end of the resistor R5, and the second end of the film capacitor Cfo is connected to the first end of the series-parallel regulation switch S3 and the second end of the external device.

[0013] A further improvement of the technical solution is that the microcontroller includes a voltage difference calculation unit, a voltage loop PI controller, a current comparator, a current difference calculation unit, a current loop PI controller, and a control / modulation algorithm unit, and the voltage difference calculation unit, the voltage loop PI controller, the current comparator, the current difference calculation unit, the current loop PI controller and the control / modulation algorithm unit are connected in sequence.

[0014] In a second aspect, the present invention provides a control method for a bidirectional wide-range DCDC module, comprising: Subtract the sampled voltage from a preset reference voltage; The calculated voltage difference generates a current reference signal after passing through the voltage loop PI controller; Compare the generated current reference signal with a preset current reference signal, and output a current reference signal with a smaller value between the two; Subtract the output current reference signal from the sampled current value; The calculated current difference passes through the current loop PI controller and is input into the control / modulation algorithm unit, where a PWM drive signal is generated after calculation.

[0015] A further improvement of the technical solution is that after the calculated current difference passes through the current loop PI controller and is input into the control / modulation algorithm unit, before the PWM drive signal is generated after calculation, it also includes: When the output side of the module is at high voltage, the series-parallel regulating switch S2 and the series-parallel regulating switch S3 are disconnected, and the series-parallel regulating switch S1 is closed. The module is configured to output series mode, and a voltage-balanced PI control loop is added for regulation before inputting to the control / modulation algorithm unit. Alternatively, when the output side of the module is low voltage and high current, the series-parallel regulation switch S1 is disconnected, the series-parallel regulation switch S2 and the series-parallel regulation switch S3 are closed, the module is configured in parallel mode, and a current sharing PI control loop is added for regulation before inputting into the control / modulation algorithm unit.

[0016] The beneficial effect of the present invention is that the bidirectional wide-range DCDC module provided by the present invention aims to solve the technical difficulties faced by the traditional bidirectional wide-range DCDC module in dealing with the high requirements of modern emergency power supply systems by introducing a series of innovative designs such as two isolated DCDC conversion circuits in parallel design, reasonable configuration of input capacitors C1 and C2, and comprehensive monitoring of microcontrollers. This design not only effectively filters out high-frequency interference, reduces the starting impact current, protects the system stability and circuit component safety, but also realizes precise control of the input side and parallel / series module power, and improves the overall efficiency and stability of the system. At the same time, the module can disperse the output current, optimize the selection of semiconductor power switch devices, reduce costs, and broaden the scope of application. In addition, through the intelligent scheduling of the microcontroller, a smooth transition between constant voltage control and constant current control functions is achieved, and the reliability and safety of the system are enhanced. Finally, by introducing series-parallel regulating switches S1, S2 and S3, the module can flexibly respond to application scenarios with different voltage ranges and input and output requirements, enhance its adaptability and flexibility, and enable it to be widely used in various emergency power supply systems.

[0017] In addition, the invention has a reliable design principle, a simple structure and a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a series-parallel adjustable bidirectional wide range DCDC module topology diagram Figure 2 It is a series-parallel adjustable bidirectional wide-range DCDC module topology diagram based on DAB converter.

[0020] Figure 3 is a schematic flow chart of the control method.

[0021] Figure 4 It is the voltage and current dual closed-loop control block diagram.

[0022] Figure 5 This is the block diagram of voltage equalization control when working in forward direction in series mode.

[0023] Figure 6 This is the block diagram of voltage equalization control when working in reverse direction in series mode.

[0024] Figure 7 This is the current sharing control block diagram when working in the forward direction in parallel mode.

[0025] Figure 8 This is the block diagram of current sharing control when working in reverse mode in parallel mode. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present invention, 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 only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] like Figure 1 As shown, the present invention provides a bidirectional wide-range DCDC module, comprising a first isolated DCDC conversion circuit, a second isolated DCDC conversion circuit, an input capacitor C1, an input capacitor C2, an input soft-start circuit, an output capacitor C3, an output capacitor C4, a series-parallel regulating switch S1, a series-parallel regulating switch S2, a series-parallel regulating switch S3, an output soft-start circuit, a microcontroller and a power supply for the entire module; the first isolated DCDC conversion circuit, the second isolated DCDC conversion circuit, the input soft-start circuit, the series-parallel regulating switch S1, the series-parallel regulating switch S2, the series-parallel regulating switch S3 and the output soft-start circuit are all connected to the microcontroller for control.

[0029] Specifically, the first input end of the first isolated DCDC conversion circuit and the first input end of the second isolated DCDC conversion circuit are both connected to the first end of the capacitor C1 and the first output end of the input soft-start circuit, the second input end of the first isolated DCDC conversion circuit and the second input end of the second isolated DCDC conversion circuit are both connected to the first end of the capacitor C2 and the second output end of the input soft-start circuit, the second end of the capacitor C1 is connected to the second end of the capacitor C2, the first input end and the second input end of the input soft-start circuit serve as the input ports of the bidirectional wide-range DCDC module, and the input port of the bidirectional wide-range DCDC module is connected to an external power supply; the first output end of the first isolated DCDC conversion circuit is connected to the first end of the output capacitor C3, the first end of the series-parallel adjustment switch S2 and the first input end of the output soft-start circuit, and the second end of the output capacitor C3 is connected to the first isolated DCDC The second output end of the conversion circuit, the second output end of the first isolated DCDC conversion circuit is connected to the first output end of the second isolated DCDC conversion circuit through the series-parallel regulation switch S1, the first output end of the second isolated DCDC conversion circuit is connected to the first end of the output capacitor C4 and the second end of the series-parallel regulation switch S2, the second end of the output capacitor C4 is connected to the second output end of the second isolated DCDC conversion circuit, the second output end of the second isolated DCDC conversion circuit is connected to the first end of the series-parallel regulation switch S3 and the second input end of the output soft-start circuit, the second end of the series-parallel regulation switch S3 is connected to the second output end of the first isolated DCDC conversion circuit, the first output end and the second output end of the output soft-start circuit serve as the output ports of the bidirectional wide-range DCDC module, and the output port of the bidirectional wide-range DCDC module is connected to the battery in the external charging and discharging system.

[0030] Among them, the input soft-start circuit includes a start switch S4, a start switch S5, a resistor R4 and a film capacitor Cfin, the first end of the start switch S4 and the first end of the start switch S5 are both connected to the first end of the external DC power supply, the second end of the start switch S4 is connected to the first end of the resistor R4, the first end of the film capacitor Cfin and the first end of the input capacitor C1, the second end of the start switch S5 is connected to the second end of the resistor R4, and the second end of the film capacitor Cfin is connected to the first end of the input capacitor C2 and the second end of the external DC power supply.

[0031] Correspondingly, the output soft-start circuit includes a start switch S6, a start switch S7, a resistor R5 and a film capacitor Cfo, the first end of the start switch S6 and the first end of the start switch S7 are both connected to the first end of the series-parallel regulation switch S2 and the first end of the film capacitor Cfo, the second end of the start switch S6 is connected to the first end of the resistor R5 and the first end of the external device, the second end of the start switch S7 is connected to the second end of the resistor R5, and the second end of the film capacitor Cfo is connected to the first end of the series-parallel regulation switch S3 and the second end of the external device.

[0032] Define the power transmission from Vin side to Vo side as forward transmission, and from Vo side to Vin side as reverse transmission. When the Vo side is low voltage and high current, disconnect the series-parallel regulating switch S1 and close the series-parallel regulating switch S2 and the series-parallel regulating switch S3 to make it work in parallel mode; when the Vo side is high voltage, close the series-parallel regulating switch S1 and disconnect the series-parallel regulating switch S2 and the series-parallel regulating switch S3 to make it work in series mode. Cfin and Cfo are the film capacitors at the input and output ports respectively, and the start switch S4, start switch S5 and start switch S6, start switch S7 are the control relays of the soft start circuit on the output side and the input side respectively.

[0033] like Figure 2 As shown, the first isolated DCDC conversion circuit includes a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, a capacitor C5, an inductor L1, a transformer T1, a capacitor C6, a MOS transistor Q5, a MOS transistor Q6, a MOS transistor Q7, a MOS transistor Q8, a MOS transistor Q9, a MOS transistor Q10, a MOS transistor Q11 and a MOS transistor Q12; the drain of the MOS transistor Q1 and the drain of the MOS transistor Q2 are both connected to the first end of the input capacitor C1, the source of the MOS transistor Q1 is connected to the drain of the MOS transistor Q3 and the first end of the primary coil of the transformer T1, the source of the MOS transistor Q2 is connected to the drain of the MOS transistor Q4 and the first end of the capacitor C5, the second end of the capacitor C5 is connected to the second end of the primary coil of the transformer T1 through the inductor L1, and the MOS transistor Q1 is connected to the drain of the MOS transistor Q3 and the first end of the primary coil of the transformer T1. The source of Q3 and the source of MOS transistor Q4 are both connected to the first end of input capacitor C2; the first end of the secondary coil of transformer T1 is connected to the source of MOS transistor Q5, the source of MOS transistor Q6, the drain of MOS transistor Q7 and the drain of MOS transistor Q8 through capacitor C6; the second end of the secondary coil of transformer T1 is connected to the source of MOS transistor Q9, the source of MOS transistor Q10, the drain of MOS transistor Q11 and the drain of MOS transistor Q12; the drain of MOS transistor Q5, the drain of MOS transistor Q6, the drain of MOS transistor Q9 and the drain of MOS transistor Q10 are all connected to the first end of output capacitor C3; the source of MOS transistor Q7, the source of MOS transistor Q8, the source of MOS transistor Q11 and the source of MOS transistor Q12 are all connected to the second end of output capacitor C3.

[0034] In addition, the second isolated DCDC conversion circuit includes a MOS transistor Q13, a MOS transistor Q14, a MOS transistor Q15, a MOS transistor Q16, a capacitor C7, an inductor L2, a transformer T2, a capacitor C8, a MOS transistor Q17, a MOS transistor Q18, a MOS transistor Q19, a MOS transistor Q20, a MOS transistor Q21, a MOS transistor Q22, a MOS transistor Q23 and a MOS transistor Q24; the drain of the MOS transistor Q13 and the drain of the MOS transistor Q14 are both connected to the first end of the input capacitor C1, the source of the MOS transistor Q13 is connected to the drain of the MOS transistor Q15 and the first end of the primary coil of the transformer T2, the source of the MOS transistor Q14 is connected to the drain of the MOS transistor Q16 and the first end of the capacitor C7, the second end of the capacitor C7 is connected to the second end of the primary coil of the transformer T2 through the inductor L2, and the MOS transistor Q13 is connected to the drain of the MOS transistor Q15 and the first end of the primary coil of the transformer T2. The source of the MOS transistor Q15 and the source of the MOS transistor Q16 are both connected to the first end of the input capacitor C2; the first end of the secondary coil of the transformer T2 is connected to the source of the MOS transistor Q17, the source of the MOS transistor Q18, the drain of the MOS transistor Q19 and the drain of the MOS transistor Q20 through the capacitor C8; the second end of the secondary coil of the transformer T2 is connected to the source of the MOS transistor Q21, the source of the MOS transistor Q22, the drain of the MOS transistor Q23 and the drain of the MOS transistor Q24; the drain of the MOS transistor Q17, the drain of the MOS transistor Q18, the drain of the MOS transistor Q21 and the drain of the MOS transistor Q22 are all connected to the first end of the output capacitor C4; the source of the MOS transistor Q19, the source of the MOS transistor Q20, the source of the MOS transistor Q23 and the source of the MOS transistor Q24 are all connected to the second end of the output capacitor C4.

[0035] In addition, the bidirectional wide-range DCDC module also includes a first current sampler R1, a second current sampler R2 and a third current sampler R3, wherein the first end of the first current sampler R1 is connected to the input end of the external device, the second end of the first current sampler R1 is connected to the first end of the input capacitor C2, the first end of the second current sampler R2 is connected to the source of the MOS tube Q12, the second end of the second current sampler R2 is connected to the second end of the output capacitor C3, the first end of the third current sampler R3 is connected to the source of the MOS tube Q24, and the second end of the third current sampler R3 is connected to the second end of the output capacitor C4.

[0036] Furthermore, the bidirectional wide-range DCDC module also includes a first voltage sampler, a second voltage sampler and a third voltage sampler, the first end of the first voltage sampler is connected to the first end of the capacitor C1, the second end of the first voltage sampler is connected to the first end of the first current sampler R1, the first end of the second voltage sampler is connected to the first end of the series-parallel regulation switch S2, the second end of the second voltage sampler is connected to the second end of the output capacitor C3, the first end of the third voltage sampler is connected to the first end of the output capacitor C4, and the second end of the third voltage sampler is connected to the first end of the series-parallel regulation switch S3.

[0037] Specifically, the microcontroller includes a voltage difference calculation unit, a voltage loop PI controller, a current comparator, a current difference calculation unit, a current loop PI controller, and a control / modulation algorithm unit, and the voltage difference calculation unit, the voltage loop PI controller, the current comparator, the current difference calculation unit, the current loop PI controller and the control / modulation algorithm unit are connected in sequence.

[0038] like Figure 3 As shown, the present invention provides a control method for a bidirectional wide-range DCDC module, comprising: Step 310, subtracting the sampled voltage from a preset reference voltage; Step 320, the calculated voltage difference is passed through a voltage loop PI controller to generate a current reference signal; Step 330, comparing the generated current reference signal with a preset current reference signal, and outputting a current reference signal having a smaller value between the two; Step 340, subtract the output current reference signal from the sampled current value; Step 350: The calculated current difference is input into the control / modulation algorithm unit after passing through the current loop PI controller, and a PWM drive signal is generated after calculation.

[0039] Specifically, assuming that the first isolated DCDC conversion circuit (converter 1) and the second isolated DCDC conversion circuit (converter 2) in the module are dual active bridge converters (DAB), ignoring the difference between the first isolated DCDC conversion circuit and the second isolated DCDC conversion circuit, the control drive signals of the first isolated DCDC conversion circuit and the second isolated DCDC conversion circuit are exactly the same regardless of the series mode or the parallel mode, and can be controlled by a set of controllers. At this time, the control block diagram is as follows: Figure 4As shown, first, it is the voltage outer loop. The user-given reference voltage is compared with the sampled actual output voltage. The error value generates a current reference signal after passing through the voltage loop PI controller. Furthermore, the current reference signal needs to be compared with the user-given current reference signal, and the smaller value is selected for output, and then the difference is made with the output current sampling value. The error value is input into the control / modulation algorithm after passing through the current loop PI controller, and a PWM drive signal is generated after calculation. The control / modulation algorithm is determined by the topology of the specific isolated DCDC converter. Taking the dual active bridge DAB topology as an example, the algorithm is a phase-shift control algorithm.

[0040] In the initial state, the module works in a constant voltage state, and the voltage loop PI output value is less than the output current reference value. At this time, the module works in a voltage and current dual closed loop state; when the load increases and the module output current exceeds the set current limit value, the output voltage decreases, and the voltage loop PI controller output increases to try to stabilize the output voltage. When the voltage loop PI controller output is greater than the output current reference value, the controller enters the current loop PI single loop control state, and the module enters the constant current state. During this state switching process, the current inner loop is always in working state, and the loop switches smoothly, so the internal current of the isolated DCDC converter will not produce instantaneous overshoot.

[0041] On the other hand, in view of the non-negligible difference between the two isolated DCC converters in the actual module, the present invention further proposes a control method for voltage and current balancing, including: When the output side of the module is at high voltage, the series-parallel regulating switch S2 and the series-parallel regulating switch S3 are disconnected, and the series-parallel regulating switch S1 is closed. The module is configured to output series mode, and a voltage-balanced PI control loop is added for regulation before inputting to the control / modulation algorithm unit. Alternatively, when the output side of the module is low voltage and high current, the series-parallel regulation switch S1 is disconnected, the series-parallel regulation switch S2 and the series-parallel regulation switch S3 are closed, the module is configured in parallel mode, and a current sharing PI control loop is added for regulation before inputting into the control / modulation algorithm unit.

[0042] Specifically, when the output side of the module is at high voltage, the series-parallel regulating switch S2 and the series-parallel regulating switch S3 are disconnected, the series-parallel regulating switch S1 is closed, and the module is configured to output series mode. At this time, due to the difference between the two DCDC converters, their respective output voltages V1o and V2o may differ greatly, causing the switch tube and output capacitor of one of the converters to be subjected to excessive voltage stress, which may cause device damage, and also cause the converter to work in a non-optimal working state, affecting efficiency. Therefore, the present invention proposes a voltage balancing control method, that is, adding a voltage balancing loop PI controller on the basis of the above-mentioned voltage and current double closed loop.

[0043] First, in addition to sampling the output voltage, the control method also needs to sample the output voltage of one of the two DCDC converters. The present invention takes sampling the output voltage of the second isolated DCDC converter circuit as an example. Figure 5 As shown, the main control loop is consistent with when the converter differences are ignored. The outermost loop is the total output voltage PI controller, which is then output to the control / modulation algorithm unit after passing through the inner loop output current PI controller. In order to compensate for the difference between the output voltages V1o and V2o, a voltage-equalizing PI control loop is added before the input of the control / modulation module of the second isolated DCDC conversion circuit for adjustment. When the module is in the forward working state, if the output voltage of the second isolated DCDC conversion circuit is low, the voltage-equalizing loop outputs a positive value, increasing the transmission power of the second isolated DCDC conversion circuit, which increases the output voltage V2o of the second isolated DCDC conversion circuit, and the total output voltage is guaranteed by the outermost loop voltage PI controller, so that V1o and V2o are equal in the end. When the module is in the reverse working state, as shown in FIG. Figure 6 As shown, the control loop is similar to the forward control loop, the difference is that the voltage outer loop control target is changed to Vin, and the voltage equalizing loop compensation value is negative.

[0044] When the output side of the module is low voltage and high current, the series-parallel regulating switch S1 is disconnected, the series-parallel regulating switch S2 and the series-parallel regulating switch S3 are closed, and the module is configured in parallel mode. Similar to the series mode, at this time, due to the difference between the two DCDC converters, their respective output currents I1 and I2 may be very different, causing the switch tube of one of the converters to be subjected to excessive current stress, which may cause device damage and affect efficiency. To address this problem, this article proposes a current equalization control method. Similar to the voltage equalization control, this control method requires sampling the total output current and the output current of one of the two converters. The present invention takes the sampling of the output current I2 of the second isolated DCDC conversion circuit as an example. When the module is in the forward working state, such as Figure 7 As shown, the main control loop is consistent with when the converter differences are ignored. The outermost loop is the total output voltage PI controller, which is then output to the control / modulation algorithm unit after passing through the inner loop output current PI controller. In order to compensate for the difference between the output currents I1 and I2, a current sharing PI control loop is added before the input of the control / modulation module of the second isolated DCDC conversion circuit for adjustment. When the module is in the forward working state, if the output current of the second isolated DCDC conversion circuit is too small, the current sharing loop outputs a positive value, increasing the transfer power of the second isolated DCDC conversion circuit, which increases the output current I2 of the second isolated DCDC conversion circuit, and the total output current is guaranteed by the inner loop current PI controller, so that I1 and I2 are equal in the end. When the module is in the reverse working state, as shown in Figure 8As shown, the control loop is similar to the forward control loop, the difference is that the voltage outer loop control target is changed to Vin, and the current sharing loop compensation value is negative.

[0045] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A bidirectional wide range DCDC module, characterized in that: It includes a first isolated DCDC conversion circuit, a second isolated DCDC conversion circuit, an input capacitor C1, an input capacitor C2, an input soft-start circuit, an output capacitor C3, an output capacitor C4, a series-parallel adjustment switch S1, a series-parallel adjustment switch S2, a series-parallel adjustment switch S3, an output soft-start circuit, a microcontroller, and a power supply for the entire module; The first input end of the first isolated DCDC conversion circuit and the first input end of the second isolated DCDC conversion circuit are both connected to the first end of the capacitor C1 and the first output end of the input soft-start circuit, the second input end of the first isolated DCDC conversion circuit and the second input end of the second isolated DCDC conversion circuit are both connected to the first end of the capacitor C2 and the second output end of the input soft-start circuit, the second end of the capacitor C1 is connected to the second end of the capacitor C2, the first input end and the second input end of the input soft-start circuit serve as input ports of the bidirectional wide-range DCDC module, and the input port of the bidirectional wide-range DCDC module is connected to an external power supply; The first output end of the first isolated DCDC conversion circuit is connected to the first end of the output capacitor C3, the first end of the series-parallel regulating switch S2 and the first input end of the output soft-start circuit, the second end of the output capacitor C3 is connected to the second output end of the first isolated DCDC conversion circuit, the second output end of the first isolated DCDC conversion circuit is connected to the first output end of the second isolated DCDC conversion circuit through the series-parallel regulating switch S1, the first output end of the second isolated DCDC conversion circuit is connected to the first end of the output capacitor C4 and the second end of the series-parallel regulating switch S2, the second end of the output capacitor C4 is connected to the second output end of the second isolated DCDC conversion circuit, the second output end of the second isolated DCDC conversion circuit is connected to the first end of the series-parallel regulating switch S3 and the second input end of the output soft-start circuit, the second end of the series-parallel regulating switch S3 is connected to the second output end of the first isolated DCDC conversion circuit, the first output end and the second output end of the output soft-start circuit serve as output ports of the bidirectional wide-range DCDC module, and the output port of the bidirectional wide-range DCDC module is connected to the battery in the external charging and discharging system; The first isolated DCDC conversion circuit, the second isolated DCDC conversion circuit, the input soft start circuit, the series-parallel regulating switch S1, the series-parallel regulating switch S2, the series-parallel regulating switch S3 and the output soft start circuit are all connected to the microcontroller control.

2. The bidirectional wide-range DCDC module according to claim 1, characterized in that: The first isolated DCDC conversion circuit includes a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, a capacitor C5, an inductor L1, a transformer T1, a capacitor C6, a MOS transistor Q5, a MOS transistor Q6, a MOS transistor Q7, a MOS transistor Q8, a MOS transistor Q9, a MOS transistor Q10, a MOS transistor Q11 and a MOS transistor Q12; The drain of the MOS transistor Q1 and the drain of the MOS transistor Q2 are both connected to the first end of the input capacitor C1, the source of the MOS transistor Q1 is connected to the drain of the MOS transistor Q3 and the first end of the primary coil of the transformer T1, the source of the MOS transistor Q2 is connected to the drain of the MOS transistor Q4 and the first end of the capacitor C5, the second end of the capacitor C5 is connected to the second end of the primary coil of the transformer T1 through the inductor L1, and the source of the MOS transistor Q3 and the source of the MOS transistor Q4 are both connected to the first end of the input capacitor C2; A first end of the secondary coil of the transformer T1 is connected to the source of the MOS transistor Q5, the source of the MOS transistor Q6, the drain of the MOS transistor Q7, and the drain of the MOS transistor Q8 through the capacitor C6, a second end of the secondary coil of the transformer T1 is connected to the source of the MOS transistor Q9, the source of the MOS transistor Q10, the drain of the MOS transistor Q11, and the drain of the MOS transistor Q12, the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, the drain of the MOS transistor Q9, and the drain of the MOS transistor Q10 are all connected to the first end of the output capacitor C3, and the source of the MOS transistor Q7, the source of the MOS transistor Q8, the source of the MOS transistor Q11, and the source of the MOS transistor Q12 are all connected to the second end of the output capacitor C3.

3. The bidirectional wide-range DCDC module according to claim 2, characterized in that: The second isolated DCDC conversion circuit includes a MOS transistor Q13, a MOS transistor Q14, a MOS transistor Q15, a MOS transistor Q16, a capacitor C7, an inductor L2, a transformer T2, a capacitor C8, a MOS transistor Q17, a MOS transistor Q18, a MOS transistor Q19, a MOS transistor Q20, a MOS transistor Q21, a MOS transistor Q22, a MOS transistor Q23 and a MOS transistor Q24; The drain of the MOS transistor Q13 and the drain of the MOS transistor Q14 are both connected to the first end of the input capacitor C1, the source of the MOS transistor Q13 is connected to the drain of the MOS transistor Q15 and the first end of the primary coil of the transformer T2, the source of the MOS transistor Q14 is connected to the drain of the MOS transistor Q16 and the first end of the capacitor C7, the second end of the capacitor C7 is connected to the second end of the primary coil of the transformer T2 through the inductor L2, and the source of the MOS transistor Q15 and the source of the MOS transistor Q16 are both connected to the first end of the input capacitor C2; A first end of the secondary coil of the transformer T2 is connected to the source of the MOS transistor Q17, the source of the MOS transistor Q18, the drain of the MOS transistor Q19, and the drain of the MOS transistor Q20 through the capacitor C8, a second end of the secondary coil of the transformer T2 is connected to the source of the MOS transistor Q21, the source of the MOS transistor Q22, the drain of the MOS transistor Q23, and the drain of the MOS transistor Q24, the drain of the MOS transistor Q17, the drain of the MOS transistor Q18, the drain of the MOS transistor Q21, and the drain of the MOS transistor Q22 are all connected to the first end of the output capacitor C4, and the source of the MOS transistor Q19, the source of the MOS transistor Q20, the source of the MOS transistor Q23, and the source of the MOS transistor Q24 are all connected to the second end of the output capacitor C4.

4. The bidirectional wide-range DCDC module according to claim 3, characterized in that: It also includes a first current sampler R1, a second current sampler R2 and a third current sampler R3, wherein a first end of the first current sampler R1 is connected to an input end of an external device, a second end of the first current sampler R1 is connected to a first end of an input capacitor C2, a first end of the second current sampler R2 is connected to a source of a MOS tube Q12, a second end of the second current sampler R2 is connected to a second end of an output capacitor C3, a first end of the third current sampler R3 is connected to a source of a MOS tube Q24, and a second end of the third current sampler R3 is connected to a second end of an output capacitor C4.

5. The bidirectional wide-range DCDC module according to claim 4, characterized in that: It also includes a first voltage sampler, a second voltage sampler and a third voltage sampler, wherein the first end of the first voltage sampler is connected to the first end of the capacitor C1, the second end of the first voltage sampler is connected to the first end of the first current sampler R1, the first end of the second voltage sampler is connected to the first end of the series-parallel regulation switch S2, the second end of the second voltage sampler is connected to the second end of the output capacitor C3, the first end of the third voltage sampler is connected to the first end of the output capacitor C4, and the second end of the third voltage sampler is connected to the first end of the series-parallel regulation switch S3.

6. The bidirectional wide-range DCDC module according to claim 1, characterized in that: The input soft-start circuit includes a start switch S4, a start switch S5, a resistor R4 and a film capacitor Cfin. The first end of the start switch S4 and the first end of the start switch S5 are both connected to the first end of the external DC power supply. The second end of the start switch S4 is connected to the first end of the resistor R4, the first end of the film capacitor Cfin and the first end of the input capacitor C1. The second end of the start switch S5 is connected to the second end of the resistor R4. The second end of the film capacitor Cfin is connected to the first end of the input capacitor C2 and the second end of the external DC power supply.

7. The bidirectional wide-range DCDC module according to claim 1, characterized in that: The output soft-start circuit includes a start switch S6, a start switch S7, a resistor R5 and a film capacitor Cfo. The first end of the start switch S6 and the first end of the start switch S7 are both connected to the first end of the series-parallel regulation switch S2 and the first end of the film capacitor Cfo. The second end of the start switch S6 is connected to the first end of the resistor R5 and the first end of the external device. The second end of the start switch S7 is connected to the second end of the resistor R5. The second end of the film capacitor Cfo is connected to the first end of the series-parallel regulation switch S3 and the second end of the external device.

8. The bidirectional wide range DCDC module according to claim 1, characterized in that: The microcontroller includes a voltage difference calculation unit, a voltage loop PI controller, a current comparator, a current difference calculation unit, a current loop PI controller, and a control / modulation algorithm unit. The voltage difference calculation unit, the voltage loop PI controller, the current comparator, the current difference calculation unit, the current loop PI controller, and the control / modulation algorithm unit are connected in sequence.

9. A control method for a bidirectional wide-range DCDC module, characterized in that: include: Subtract the sampled voltage from a preset reference voltage; The calculated voltage difference generates a current reference signal after passing through the voltage loop PI controller; Compare the generated current reference signal with a preset current reference signal, and output a current reference signal with a smaller value between the two; Subtract the output current reference signal from the sampled current value; The calculated current difference passes through the current loop PI controller and is input into the control / modulation algorithm unit, where a PWM drive signal is generated after calculation.

10. The control method of the bidirectional wide range DCDC module according to claim 9, characterized in that: The calculated current difference is input into the control / modulation algorithm unit after passing through the current loop PI controller, and before generating the PWM drive signal after calculation, it also includes: When the output side of the module is at high voltage, the series-parallel regulating switch S2 and the series-parallel regulating switch S3 are disconnected, and the series-parallel regulating switch S1 is closed. The module is configured to output series mode, and a voltage-balanced PI control loop is added for regulation before inputting to the control / modulation algorithm unit. Alternatively, when the output side of the module is low voltage and high current, the series-parallel regulation switch S1 is disconnected, the series-parallel regulation switch S2 and the series-parallel regulation switch S3 are closed, the module is configured in parallel mode, and a current sharing PI control loop is added for regulation before inputting into the control / modulation algorithm unit.

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