Hierarchical control system of efficient discrete magnetic integrated power supply and control method thereof

Abstract

The invention provides a hierarchical control system of an efficient discrete magnetic integrated power supply and a control method thereof, which are applied to the technical field of micro inverters, and comprise a power supply circuit, a high-level power management module and a low-level PWM control module, the power supply circuit comprises a transformer T1 and a transformer T2 which are connected in parallel, one of the two transformers is a magnetic integrated transformer, and the other transformer is a discrete transformer; the high-level power management module is used for performing intelligent decision making according to the power requirement of the power supply system, a transformer connected to the power supply system is selected, the decision made by the high-level power management module is executed through the low-level PWM control module, the power supply system is accurately controlled, accurate staggered connection of the transformer is achieved through hierarchical control, and the power supply system is more accurate. And the working efficiency of the power supply system is maximized on the basis of ensuring the normal work of the power supply system.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro inverters, and in particular relates to a hierarchical control system of a high-efficiency discrete magnetic integrated power supply. Background Art

[0002] The flyback converter has the functions of boosting and high-frequency isolation, and has a simple topology, few switching devices, simple control, and low cost. It is the mainstream topology of PVMI at present. However, the power level of a single-channel flyback is generally 50W to 150W, which cannot meet the power level requirements of PVMI. Therefore, an interleaved flyback micro-power photovoltaic grid-connected inverter (referred to as an interleaved flyback micro-inverter) with a two-channel flyback parallel structure is adopted. The two-channel flyback converters are connected in parallel and connected to the grid after the power frequency polarity reversal bridge and filter. The interleaved parallel structure improves the power level of the inverter.

[0003] However, currently, the two transformers of the two-way flyback converter connected in parallel both adopt a discrete transformer structure, and the discrete transformer is relatively large in size. Moreover, while the two-way flyback converter improves the power level of the inverter, the working efficiency is not high. Summary of the invention

[0004] In view of the above-mentioned problems in the prior art, the purpose of the present invention is to provide a hierarchical control system for a high-efficiency discrete magnetic integrated power supply, which adopts a magnetic integrated transformer and a discrete transformer to form a parallel interleaved flyback micro-inverter structure, and uses a high-level power management module to make intelligent decisions according to the power demand of the power supply system, select the transformer connected to the power supply system, and execute the decision made by the high-level power management module through the low-level PWM control module to accurately control the power supply system. Through hierarchical control, accurate interleaved access of transformers is achieved, and the working efficiency of the power supply system is maximized on the basis of ensuring the normal operation of the power supply system.

[0005] A hierarchical control system for a highly efficient discrete magnetic integrated power supply comprises a power supply circuit, a high-level power management module and a low-level PWM control module; the power supply circuit comprises a transformer T1 and a transformer T2 connected in parallel, one of the two transformers is a magnetic integrated transformer, and the other is a discrete transformer; the input ends of the transformers T1 and T2 are respectively driven by a switch tube and connected to a power supply system, and the output ends of the transformers T1 and T2 are respectively driven by a polarity reversal bridge and connected to the power supply system; the high-level power management module is used to make intelligent decisions according to the power required by the current load, select a corresponding transformer to be connected to the power supply system, so that the power supply system can meet the load demand while maximizing the efficiency, and generate a corresponding instruction set to transmit to the low-level PWM control module; the low-level PWM control module is used to adjust the duty cycle of the PWM signal to drive the corresponding switch tube, connect the transformer selected by the high-level power management module to the power supply system, so that the power supply system can meet the load demand while maximizing the working efficiency.

[0006] Preferably, the input voltage Vin of the power supply circuit is connected to the decoupling capacitor C decoup The input end of the transformer T1 and the transformer T2 are connected. The input end of the transformer T1 is connected to the switch tube Q1, and the output end is connected to the polarity reversal bridge through the rectifier diode VD1; the input end of the transformer T2 is connected to the switch tube Q2, and the output end is connected to the polarity reversal bridge through the rectifier diode VD2. The output signal of the polarity reversal bridge passes through the filter and then outputs the grid-connected current i o , grid voltage v grid ; The switch tubes Q1 and Q2 are driven by the PWM signals output by the low-level PWM control module.

[0007] Preferably, an active clamping circuit 1 is configured at the switch tube Q1, and the active clamping circuit 1 includes a capacitor C1 and a switch tube Q3; an active clamping circuit 2 is configured at the switch tube Q2, and the active clamping circuit 2 includes a capacitor C2 and a switch tube Q4.

[0008] Preferably, the polarity reversal bridge comprises a thyristor T4, a thyristor T5, a MOS tube Q5, and a MOS tube Q6, and the polarity reversal bridge is connected to the grid according to the grid voltage v grid The polarity changes and switches on and off alternately. When the grid voltage v grid In the positive half cycle, transformer T1 and MOS tube Q6 are turned on, and transformer T1 is connected to the power supply system; when the grid voltage v grid In the negative half cycle, transformer T2 and MOS tube Q5 are turned on, and transformer T2 is connected to the power supply system.

[0009] Preferably, the low-level PWM control module includes:

[0010] ADC module, used to collect input voltage v in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid ;

[0011] Phase-locked loop, used to convert the grid voltage v grid The frequency and phase are adjusted to be synchronized with the grid voltage to form a standard sinusoidal signal;

[0012] PI regulator is used to adjust the grid current i o , reference current i oref Calculate the dynamic duty cycle Δd, the reference current i oref Related to the standard sinusoidal signal;

[0013] Feedforward compensation module is used to adjust the grid voltage v grid and input voltage vin Calculate the steady-state duty cycle d;

[0014] The current sharing control module is used to control the primary current i p1 、Flyback primary current i p2 Calculate the duty cycle correction term Δd';

[0015] The PWM signal generating module is used to output a corresponding PWM signal according to the calculated duty cycle D to drive the corresponding transformer to be connected to the power supply system, wherein the duty cycle D=d+Δd±Δd'.

[0016] Preferably, the dynamic duty cycle Δd=(K p +K i / s)*(i oref -i o ), where the reference current i oref Produced by multiplying the standard sinusoidal signal by the current given value, (K p +K i / s) is the transfer function of the PI regulator; steady-state duty cycle d = v grid / (v grid +nv in ), where n is the turns ratio of the primary and secondary sides of the transformer; duty cycle correction term Δd'=(K p '+K i ' / s)*(i p1 -i p2 ), where (K p '+K i ' / s) is the transfer function of the PI regulator during the current sharing control process.

[0017] Preferably, the process of the PWM signal driving the transformer input end to connect to the power supply system and the process of the polarity reversal bridge driving the transformer output end to connect to the power supply system are coordinated and synchronized with each other.

[0018] Another object of the present invention is to provide a control method for a high-efficiency discrete magnetic integrated power supply, which is applicable to the hierarchical control system of the high-efficiency discrete magnetic integrated power supply, and comprises the following steps:

[0019] Real-time monitoring of the power required by the load in the power supply system, the power including reactive power and active power;

[0020] The high-level power management module selects the corresponding transformer to connect to the power supply system according to the power demand of the current load, and generates the corresponding instruction set to be transmitted to the low-level PWM control module;

[0021] The low-level PWM control module adjusts the duty cycle of the PWM signal according to the instructions of the high-level power management module to drive the corresponding switch tube to conduct, so that the transformer selected by the high-level power management module is connected to the power supply system;

[0022] The polarity reversal bridge in the power supply circuit is based on the grid voltage v grid The polarity of turns on the corresponding switch tube to connect the corresponding transformer;

[0023] The low-level PWM control module monitors the grid-connected voltage v output by the power supply system in real time grid and grid current i o and feeds the data back to the high-level power management module to achieve dynamic adjustment;

[0024] The process of the low-level PWM control module driving the transformer to access the power supply system is coordinated and synchronized with the process of the polarity reversal bridge driving the transformer to access the power supply system.

[0025] Preferably, the operation process of the low-level PWM control module is as follows:

[0026] Acquisition signal: real-time acquisition of input voltage v in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid ;

[0027] Obtain a standard sinusoidal signal: grid Input into the phase-locked loop to generate a standard sinusoidal signal with the same frequency and phase as the grid voltage;

[0028] Calculate the dynamic duty cycle Δd: Multiply the standard sinusoidal signal by the current given value to calculate the reference current i oref , and the grid-connected current i o With reference current i oref The error signal between the two generates a dynamic duty cycle Δd through the PI regulator. The transfer function of the PI regulator is (K p +K i / s), so the dynamic duty cycle Δd=(K p +K i / s)*(i oref -i o );

[0029] Calculate the steady-state duty cycle d: grid voltage v grid and input voltage v in The steady-state duty cycle d=v is obtained by the feedforward compensation module. grid / (v grid +nv in ), where n is the transformer primary-to-secondary turns ratio;

[0030] Calculate the duty cycle correction term Δd': The flyback primary current i p1、Flyback primary current i p2 PI regulation is performed, and the transfer function of the PI regulator for current sharing control is (K p '+K i ' / s), so the output duty cycle correction term Δd'=(K p '+K i ' / s)*(i p1 -i p2 );

[0031] Calculate the duty cycle D of the power supply system according to the dynamic duty cycle Δd, the steady-state duty cycle d, and the duty cycle correction term Δd', where the duty cycle D=d+Δd±Δd';

[0032] Output PWM signal: Output the corresponding PWM signal according to the calculated duty cycle D to drive the corresponding switch tube to conduct, so that the transformer selected by the high-level power management module is connected to the power supply system;

[0033] Data feedback: Real-time monitoring of the grid-connected voltage v output by the power supply system grid and grid current i o and feeds the data back to the high-level power management module to achieve dynamic adjustment.

[0034] Preferably, the specific process of coordinated synchronization between the process of the low-level PWM control module driving the transformer to access the power supply system and the process of the polarity reversal bridge driving the transformer to access the power supply system is as follows:

[0035] Determine the real-time collected grid voltage v grid Whether the polarity of changes, if the grid voltage v grid If the polarity of the input voltage changes, the phase angle θ is reset to zero, the phase angle increment Δθ is recalculated, and the polarity reversal bridge is driven to flip, thereby driving the corresponding transformer output end to connect to the power supply system;

[0036] If the grid voltage v grid If the polarity of does not change, the phase angle θ is accumulated, and the current given value is obtained by looking up the sine table according to the phase, thereby calculating the reference current i oref , according to the reference current i oref Calculate the dynamic duty cycle Δd, thereby determining the duty cycle D;

[0037] According to the result of the duty cycle D, a corresponding PWM signal is output to drive the corresponding transformer input end to connect to the power supply system.

[0038] The beneficial effects of the present invention are as follows: the hierarchical control system and control method of the high-efficiency discrete magnetic integrated power supply adopts a magnetic integrated transformer and a discrete transformer to form a parallel interleaved flyback micro-inverter structure, and utilizes the characteristics of the magnetic integrated transformer and the discrete transformer to select the transformer connected to the power supply system according to the power required by the current load while meeting the power supply demand of the power supply system, so as to maximize the working efficiency of the power supply system.

[0039] A high-level power management module is set up to make intelligent decisions based on the real-time monitoring of load power requirements, select the transformers connected to the power supply system, and then execute the decisions made by the high-level power management module through the low-level PWM control module to accurately control the power supply system. Accurate staggered access of transformers is achieved through hierarchical control, which maximizes the working efficiency of the power supply system while ensuring the normal operation of the power supply system.

[0040] During the execution of the low-level PWM control module, the corresponding switch tube is turned on by adjusting the duty cycle of the PWM signal to drive the corresponding transformer input end to connect to the power supply system, and the corresponding switch tube is turned on by the polarity reversal bridge to drive the corresponding transformer output end to connect to the power supply system, so that the power supply system can work normally. At the same time, through the mutual correlation and signal feedback between the polarity reversal bridge drive and the PWM signal drive, the efficiency and accuracy of the power supply system switching are improved, which can further improve the working efficiency of the power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 is a circuit diagram of a power supply circuit of the present invention;

[0043] Figure 2 is the grid-connected voltage vgrid, grid-connected current io, instantaneous output power P of the present invention. o (ωt) and the voltage across the decoupling capacitor v c Waveform diagram of

[0044] Figure 3 is a comparison diagram of efficiency curves of different transformers connected to the power supply system of the present invention;

[0045] Figure 4 is the grid-connected current i when the magnetic integrated transformer of the present invention is connected to the power supply system o With grid voltage v grid Experimental waveform expansion diagram;

[0046] Figure 5 When the magnetic integrated transformer of the present invention is connected to the power supply system, v under different duty cyclesgs1 、v ds1 Experimental waveform expansion diagram;

[0047] Figure 6 When the magnetic integrated transformer of the present invention is connected to the power supply system, the i p1 with i p2 Experimental waveform expansion diagram;

[0048] Figure 7 When the magnetic integrated transformer of the present invention is connected to the power supply system, the i p1 、i s1 Experimental waveform expansion diagram;

[0049] Figure 8 is a block diagram of a low-level PWM control module of the present invention;

[0050] Fig. 9 is a flow chart of the grid-connected current control of the present invention;

[0051] Fig.10 It is a flow chart of the current sharing control of the present invention. DETAILED DESCRIPTION

[0052] Embodiment 1

[0053] like Figure 1 As shown, a high-efficiency discrete magnetic integrated power supply circuit includes a transformer T1 and a transformer T2 connected in parallel. The input voltage Vin is connected through a decoupling capacitor C decoup The input end of the transformer T1 and the transformer T2 are connected. The input end of the transformer T1 is connected to the switch tube Q1, and the output end is connected to the polarity reversal bridge through the rectifier diode VD1; the input end of the transformer T2 is connected to the switch tube Q2, and the output end is connected to the polarity reversal bridge through the rectifier diode VD2. The output signal of the polarity reversal bridge passes through the filter and then outputs the grid-connected current i o , grid voltage v grid The filter in this embodiment is composed of capacitor C f and inductor L f composition.

[0054] The transformer connected to the power supply system is selected through the cooperation between the switch tube Q1, the switch tube Q2 and the polarity reversal bridge, so as to realize the staggered connection of the transformer T1 and the transformer T2. Among them, the switch tube Q1 and the switch tube Q2 are driven and controlled by the PWM signal, and the polarity reversal bridge is driven by the grid voltage v grid Drive control. The PWM signal is adjusted according to the real-time data of the power supply system, and the corresponding transformer is selected to connect to the power supply system, so that the power supply system can maximize its working efficiency while ensuring the load power demand.

[0055] It should be noted that in this embodiment, one of the transformers T1 and T2 is a magnetic integrated transformer, and the other transformer is a discrete transformer opposite to the magnetic integrated transformer. Therefore, under the condition of meeting the power supply demand of the power supply system, the characteristics of the magnetic integrated transformer and the discrete transformer are used to control the on and off of the switch tubes Q1 and Q2 according to the power required by the current load, so as to select the transformer connected to the circuit as the transformer T1 or the transformer T2, so that the parallel transformers T1 and T2 are staggeredly connected to the circuit to maximize the efficiency of the entire circuit.

[0056] In addition, in order to absorb the voltage spike generated when the switch tubes Q1 and Q2 are turned off, an active clamping circuit 1 is configured at the switch tube Q1, and an active clamping circuit 2 is configured at the switch tube Q2. The active clamping circuit 1 includes a capacitor C1 and a switch tube Q3, and the active clamping circuit 2 includes a capacitor C2 and a switch tube Q4.

[0057] Specifically, take the active clamping circuit 1 as an example: when the switch tube Q1 is turned off, the voltage spike energy charges the capacitor C1 through the body diode of the switch tube Q3, and the drain-source voltage of the switch tube Q1 is clamped at the voltage across the capacitor C1. Then the switch tube Q3 is turned on, and the capacitor C1 discharges to the input side through the switch tube Q3, thereby achieving lossless absorption of the voltage spike energy when the switch tube Q1 is turned off.

[0058] For the polarity reversal bridge, compared with the polarity reversal bridge structure formed by four thyristors in the prior art, the polarity reversal bridge of this embodiment adopts a structure of two thyristors and two switch tubes, specifically including the following: Figure 1 The thyristor T4, thyristor T5, MOS tube Q5, and MOS tube Q6 shown in the figure are connected to the grid when the thyristor current i o and grid voltage v grid Automatically shutting down at zero crossing can prevent grid energy from being input into the power supply system, causing the power supply system to fail. The use of two MOS tubes is to effectively reduce the conduction loss of the polarity reversal bridge. Specifically, the polarity reversal bridge is based on the grid voltage v grid The polarity of the switch is switched on and off alternately. When the grid voltage v grid In the positive half cycle, transformer T1 and MOS tube Q6 are turned on, and transformer T1 is connected to the power supply system; when the grid voltage v grid In the negative half cycle, transformer T2 and MOS tube Q5 are turned on, and transformer T2 is connected to the power supply system.

[0059] For the decoupling capacitor, its function is to buffer the power difference between input and output. When the instantaneous output power P of the power supply system o When (ωt) is less than the input power Pin, the decoupling capacitor is in a charging state; when P o When (ωt) is greater than Pin, the decoupling capacitor is in a discharged state.

[0060] In a specific embodiment, Figure 1 As shown, assuming that the power factor of the high-efficiency discrete magnetic integrated power supply circuit is 1, the grid-connected voltage v grid and grid current i o The expressions are:

[0061] v grid (ωt)=V grid_pk sin(ωt) (1-1)

[0062] i o (ωt)=I o_pk sin(ωt) (1-2)

[0063] Among them, V grid_pk is the grid voltage v grid The peak value, I o_pk is the grid-connected current i o Peak value, ω=2πf o , then the instantaneous output power of the power supply system is:

[0064]

[0065] Assuming the system conversion efficiency is 100%, the system input power P in Equal to the output average power, that is:

[0066]

[0067] From formula (1-3), we can see that the output power of the power supply system fluctuates at twice the power frequency, which makes it impossible for the photovoltaic panel to output at maximum power. Therefore, the output and input can be decoupled by electrolytic capacitors. The voltage across the decoupling capacitor is equal to the input voltage, so the current i c and voltage v c The expression is as follows:

[0068] i c (ωt)=I in cos(2ωt) (1-5)

[0069]

[0070] Among them, V c is the average voltage across the decoupling capacitor.

[0071] Grid voltage vgrid, grid current io, instantaneous output power P o (ωt) and the waveform of the voltage vc across the decoupling capacitor Cdecoup is as follows Figure 2 As shown. When the instantaneous output power P of the power supply systemo When (ωt) is less than the input power Pin, the decoupling capacitor Cdecoup is charged; when P o When (ωt) is greater than Pin, the decoupling capacitor Cdecoup discharges. The function of the decoupling capacitor Cdecoup is to buffer the power difference between input and output, as shown in formula (1-7):

[0072]

[0073] The energy absorbed by it is E c for:

[0074]

[0075] The solution of equations (1-4) to (1-8) is:

[0076]

[0077] Where Δv c is the decoupling capacitor C decoup voltage ripple.

[0078] In this embodiment, in order to ensure that the utilization rate of the photovoltaic panel is not less than 98%, the voltage ripple is less than 8.5% of the maximum power point voltage. The maximum power point voltage is taken as 36V, then Δv c =8.5%*36=3.06V, P in =220W, V c =36V, f o =50Hz Substituting into formula (1-9) we can get C decoup =6357uF. In actual use, four 2200uF / 63V aluminum electrolytic capacitors can be connected in parallel.

[0079] Since the discrete transformers and magnetic integrated transformers connected in parallel need to be selectively connected to the power supply system according to the load demand power monitored in real time, in a specific embodiment, based on the following power supply system parameter design, the data of the power supply system when connected to different transformers is recorded.

[0080] The parameters of the power supply system in this embodiment are as follows:

[0081] Rated grid-connected voltage: V grid =220V ac ±10%;

[0082] Maximum grid-connected power: P o =220W;

[0083] The system allows input voltage range: 16V dc ~45V dc ;

[0084] MPPT voltage tracking range: V inmin =22V dc , V inmax =36V dc ;

[0085] Rated grid-connected frequency: f o =50Hz;

[0086] Grid-connected frequency range f omin =49.5Hz, f omax =50.5Hz;

[0087] Grid-connected current total harmonic distortion: THD≤5%;

[0088] Power factor: PF ≥ 0.95;

[0089] Peak efficiency: η≥92%.

[0090] For the discrete transformer, in order to meet the above power supply system parameter requirements, the core of the discrete transformer is set to EEW43.2B ferrite core, the material model is DMR44, and its parameters are: core effective cross-sectional area AP = 44328.37mm4, window area Aw = 196.84mm2, center column area Ae0 = 225.2mm2. Take the peak-to-peak value of the AC magnetic flux density ΔB = 0.12T, the number of turns of the primary winding of the discrete transformer N p =6, then the number of turns of the secondary winding is N s =42.

[0091] For the magnetic integrated transformer, in order to meet the above power supply system parameter requirements, the magnetic core of the magnetic integrated transformer is set to EEW58.4A ferrite core, the material model is DMR44, and its related parameters are: effective cross-sectional area AP = 81432.65mm 4 , window area A w =160.02mm 2 , the area of ​​the middle column is A e0 =299mm 2 The number of turns of the primary and secondary sides of the coupled magnetic integrated transformer are N p =6, N s =4.

[0092] Based on the comparison of the number of turns of the primary and secondary sides of the separation transformer and the number of turns of the primary and secondary sides of the magnetic integrated transformer, it can be seen that the volume of the magnetic integrated transformer is smaller while meeting the parameter design of the power supply system.

[0093] During the experiment, set the input voltage V in =30V, grid voltage V grid =220V, grid current I o=0.3~1.0A, record the data of discrete transformer and magnetic integrated transformer connected to the power supply system, as shown in Table 5-1 and Table 5-2, where Table 5-1 is the experimental data of the discrete solution prototype; Table 5-2 is the experimental data of the planar magnetic integrated solution prototype. The efficiency curve comparison diagram of the discrete transformer and the planar magnetic integrated transformer obtained based on the experimental data shown in Table 5-1 and Table 5-2 is shown in Figure 3 shown.

[0094] Table 5-1 Discrete solution prototype experimental data

[0095]

[0096] Table 5-2 Experimental data of prototype of planar magnetic integration solution

[0097]

[0098] according to Figure 3 It can be seen that the peak efficiency of the separation transformer and the peak efficiency of the magnetic integrated transformer are both related to the size of the grid-connected active power.

[0099] On the basis of satisfying the power supply system parameter design, when the grid-connected active power is less than the boundary value, the peak efficiency is higher when the separation transformer is connected under the same circumstances, and when the grid-connected active power is greater than the boundary value, the peak efficiency is higher when the magnetic integrated transformer is connected under the same circumstances. Among them, the size of the boundary value varies according to the design of the power supply system and is not limited here.

[0100] Therefore, on the basis of meeting the load power requirements, by utilizing the characteristics of discrete transformers and magnetic integrated transformers and accurately controlling the type of connected transformers, the power supply system efficiency can be effectively maximized.

[0101] In addition, during the process of recording experimental data, the waveform diagrams of various signals were recorded by taking the connection of magnetic integrated transformer as an example.

[0102] (1) Set the input voltage V in =30V, grid voltage V grid =220V, different grid current I o The grid voltage V grid With the grid current i o The experimental waveform is as follows Figure 4 As shown. Figure 4 (a) shows the grid-connected current i o When the grid voltage is 0.3A, V grid With the grid current i o The waveform of Figure 4 (b) shows the grid-connected current i o When the grid voltage is 0.5A, Vgrid and grid-connected current i o waveform; Attached Figure 4 (c) shows the grid-connected current i o when it is 0.7 A, the grid-connected voltage V grid and grid-connected current i o waveform; Attached Figure 4 (d) shows the grid-connected current i o when it is 1.0 A, the grid-connected voltage V grid and grid-connected current i o waveform. Since the attached Figure 4 (a)-(d) the grid-connected current i o waveform is approximately a sine wave and is in the same frequency and phase as the grid-connected voltage v grid , it verifies the feasibility of the grid-connected current control strategy in the magnetic integration transformer scheme.

[0103] (2) Set the input voltage V in = 30 V, grid-connected voltage V grid = 220 V, grid current I o = 1.0 A, the experimental waveform expansion diagrams of v gs1 and v ds1 at different duty cycles are as shown in Figure 5 . Among them, attached Figure 5 (a) shows the waveforms of v gs1 and v ds1 when 0 < D < 0.5; Attached Figure 5 (b) shows the waveforms of v gs1 and v ds1 when D = 0.5; Attached Figure 5 (c) shows the waveforms of v gs1 and v ds1 when 0.5 < D < 1. According to Figure 5 (a)-(c), the active clamping circuit effectively limits the voltage spike between the drain and source when the switch Q1 turns off, reducing the voltage stress on the MOS transistor.

[0104] (3) The experimental waveform expansions of i p1 and i p2 at different duty cycles are as shown in Figure 6 . Among them, attached Figure 6 (a) shows the waveforms of i p1 and i p2 when 0 < D < 0.5; Attached Figure 6 (b) shows the waveforms of i p1 and i p2 when D = 0.5; Attached Figure 6 (c) shows the waveforms of i p1 and i p2The waveform. According to Figure 6 (a)-(c), it can be seen that i p1 and i p2 are approximately sinusoidal double half-waves within one power grid cycle, and the current sharing control is well achieved.

[0105] (4) Under different duty cycles, the waveforms of the primary current i p1 and the secondary current i s1 of the transformer T1 are shown in the expanded experimental waveforms as Figure 7 shown. Among them, Figure 7 as shown in Fig. (a), the waveforms of i p1 and i s1 when 0 < D < 0.5 are shown; Figure 7 as shown in Fig. (b), the waveforms of i p1 and i s1 when D = 0.5 are shown; Figure 7 as shown in Fig. (c), the waveforms of i p1 and i s1 when 0.5 < D < 1 are shown. According to Figure 7 (a)-(c), it can be seen that when the duty cycle is relatively large, the instantaneous power is relatively large. After the primary main MOS transistor is turned off, the resonant energy of the primary inductor and the clamping capacitor is relatively large, and obvious resonant phenomena occur in i p1 and i s1 . Under high load conditions, the magnetically integrated transformer performs well in power management, working efficiency, and current waveform control.

[0106] Embodiment 2

[0107] A hierarchical control system for an efficient discrete magnetically integrated power supply includes a power supply circuit, a high-level power management module, and a low-level PWM control module as described in Embodiment 1. Among them, the high-level power management module makes intelligent decisions according to the power demand of the power supply system, reasonably allocates system resources to achieve global optimization, and the low-level PWM control module executes the decisions made by the high-level power management module, precisely controls the power supply system, and realizes the accurate interleaved connection of the transformer through hierarchical control, maximizing the working efficiency of the power supply system while ensuring the normal operation of the power supply system.

[0108] Specifically, the high-level power management module makes intelligent decisions according to the actual power required by the load obtained in real time, selects the corresponding transformer to participate in the circuit operation, maximizes the efficiency of the power supply system under different load conditions, optimally allocates system resources, and generates an instruction set to be transmitted to the low-level PWM control module. Specifically, the active power and reactive power demand data of the current load can be obtained through existing sensors and metering devices.

[0109] After receiving the instruction set transmitted by the high-level power management module, the low-level PWM control module drives the corresponding switch tube to conduct so that the corresponding transformer is connected to the power supply system, and adjusts the duty cycle D of the PWM signal to ensure that the current waveform output by the power supply circuit is good and the power transmission is stable. At the same time, the low-level PWM control module also monitors the grid-connected voltage v output by the power supply system in real time. grid and grid current i o And feed back the data to the high-level power management module to achieve dynamic adjustment, so as to enable the high-level power management module to make more accurate decisions.

[0110] In addition, the flipping of the polarity reversal bridge in the power supply circuit requires the current direction to change in time, and the selection of the transformer often involves physical connection and switching timing, which may cause instability in the intermediate state or difficulty in switching. If the transformer is not switched in time, it may cause the interruption of power transmission, which in turn affects the coordination of energy adjustment and polarity reversal. Therefore, it is necessary to set the synchronization of the two processes of polarity reversal and transformer selection access to ensure the compatibility and coordination of the two operations at the software and hardware levels. In addition, it is necessary to dynamically adjust the execution order and strategy of the two processes of polarity reversal and transformer selection access according to the operation priority, such as selecting the transformer after polarity reversal, or designing a circuit with fast response capability to improve switching efficiency. Finally, it is necessary to find the best coordination time of current reversal and transformer access through simulation and actual testing, and adjust the control algorithm and hardware connection. Effectively solving the potential contradiction between "polarity reversal" and "transformer selection" can improve the overall stability and efficiency of the power supply system.

[0111] Embodiment 3

[0112] like Figure 8 As shown, the structure of this embodiment is basically the same as that of the second embodiment, except that the low-level PWM control module of this embodiment includes an ADC module, a phase-locked loop, a PI regulator, a feedforward compensation module, a current sharing control module and a PWM signal generating module.

[0113] Among them, the ADC module is used to collect the input voltage v in real time in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid .

[0114] The phase-locked loop is used to convert the grid voltage v grid The frequency and phase are adjusted to be synchronized with the grid voltage to form a standard sinusoidal signal.

[0115] The PI regulator is used to adjust the grid current i o , reference current i orefThe dynamic duty cycle Δd is calculated by the difference between K and . Dynamic duty cycle Δd = (K p +K i / s)*(i oref -i o ), where the reference current i oref Produced by multiplying the standard sinusoidal signal by the current given value, (K p +K i / s) is the transfer function of the PI regulator.

[0116] The feedforward compensation module is used to adjust the grid voltage v grid and input voltage v in And produce steady-state duty cycle d. Steady-state duty cycle d = v grid / (v grid +nv in ), where n is the turns ratio of the primary and secondary sides of the transformer. The feedforward compensation module can reduce the impact of grid disturbances on the low-level PWM control module, thereby improving the stability and accuracy of the low-level PWM control module.

[0117] The current sharing control module is used to control the primary current i p1 、Flyback primary current i p2 The duty cycle correction term Δd' is generated. Duty cycle correction term Δd' = (K p '+K i ' / s)*(i p1 -i p2 ), where (K p '+K i ' / s) is the transfer function of the PI regulator during the current sharing control process.

[0118] The duty cycle D of the power supply system is calculated according to the dynamic duty cycle Δd, the steady-state duty cycle d, and the duty cycle correction term Δd', wherein the duty cycle D=d+Δd±Δd'.

[0119] The PWM signal generation module is used to output a corresponding PWM signal according to the result of the duty cycle D to drive the corresponding switch tube to turn on, so that the corresponding transformer is connected to the power supply system.

[0120] like Fig. 9 As shown, the grid-connected current control process is as follows:

[0121] The analog signal is sampled through the ADC module to obtain the input voltage v in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid .

[0122] Determine the grid voltage vgrid Whether the polarity of changes, if the grid voltage v grid The polarity of the grid voltage v grid The phase angle θ is reset, the phase angle increment Δθ is recalculated, and the polarity reversal bridge is controlled to flip, thereby driving the corresponding transformer output end to connect to the power supply system.

[0123] If the polarity remains unchanged, the phase angle θ is accumulated, and the current given value is obtained by looking up the sine table according to the phase, thereby calculating the reference current i oref , according to the reference current i oref The dynamic duty cycle Δd is calculated to determine the duty cycle D, and the duty cycle D is loaded into the duty cycle register of the PWM module, wherein D=d+Δd±Δd.

[0124] According to the duty cycle D, a corresponding PWM signal is output to drive the corresponding transformer input end to connect to the power supply system.

[0125] Since the parameters of the power semiconductor devices and transformers of the two flybacks cannot be completely consistent, in order to ensure that the power of the two flybacks can be balanced under the same duty cycle, the duty cycle of each flyback is corrected through the current sharing control module. Fig.10 As shown in the figure, the current sharing control process is as follows:

[0126] Calculate the flyback primary current i p1 、Flyback primary current i p2 The difference Δi between them is adjusted by PI to obtain the duty cycle correction term Δd', the duty cycle correction term Δd'=(K p '+K i ' / s)*(i p1 -i p2 ), use the duty cycle correction term Δd' to correct the duty cycles D1 and D2 of the two flybacks, and then load D1 and D2 into the duty cycle register of the PWM module.

[0127] Embodiment 4

[0128] A second aspect of the present invention provides a hierarchical control method for a high-efficiency discrete magnetic integrated power supply, which specifically comprises the following steps:

[0129] Real-time monitoring of the power required by the load in the power supply system. The power required by the load includes reactive power and active power.

[0130] The high-level power management module selects the corresponding transformer to connect to the power supply system according to the power demand of the current load, and generates a corresponding instruction set to transmit to the low-level PWM control module.

[0131] The low-level PWM control module adjusts the duty cycle of the PWM signal according to the instructions of the high-level power management module to drive the corresponding switch tube to conduct, so that the transformer selected by the high-level power management module is connected to the power supply system.

[0132] Specifically, the low-level PWM control module controls the power supply system as follows:

[0133] Acquisition signal: real-time acquisition of input voltage v through ADC module in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid .

[0134] Obtain a standard sinusoidal signal: grid It is input into the phase-locked loop to generate a standard sinusoidal signal with the same frequency and phase as the grid voltage.

[0135] Calculate the dynamic duty cycle Δd: Multiply the standard sinusoidal signal by the current given value to calculate the reference current i oref , and the grid-connected current i o With reference current i oref The error signal between the two generates a dynamic duty cycle Δd through the PI regulator. The transfer function of the PI regulator is (K p +K i / s), so the dynamic duty cycle Δd=(K p +K i / s)*(i oref -i o ).

[0136] Calculate the steady-state duty cycle d: grid voltage v grid and input voltage v in The steady-state duty cycle d=v is obtained by the feedforward compensation module. grid / (v grid +nv in ), where n is the ratio of the primary and secondary turns of the transformer.

[0137] Calculate the duty cycle correction term Δd': The flyback primary current i p1 、Flyback primary current i p2 PI regulation is performed, and the transfer function of PI regulation of current sharing control is (K p '+K i ' / s), so the output duty cycle correction term Δd'=(K p '+K i ' / s)*(i p1 -i p2 ).

[0138] The duty cycle D of the power supply system is calculated according to the dynamic duty cycle Δd, the steady-state duty cycle d, and the duty cycle correction term Δd', wherein the duty cycle D=d+Δd±Δd'.

[0139] Output PWM signal: Output the corresponding PWM signal according to the calculated duty cycle D to drive the corresponding switch tube to turn on, so that the transformer selected by the high-level power management module is connected to the power supply system.

[0140] Data feedback: Real-time monitoring of the grid-connected voltage v output by the power supply system grid and grid current i o and feeds the data back to the high-level power management module to achieve dynamic adjustment.

[0141] The polarity reversal bridge in the power supply circuit is based on the grid voltage v grid The polarity turns on the corresponding switch tube to connect the corresponding transformer.

[0142] Among them, the input end of the low-level PWM control module drives the transformer to be connected to the power supply system, and the polarity reversal bridge in the power supply circuit drives the output end of the transformer to be connected to the power supply system, so that the transformer can work normally in the power supply system. It should be noted that the process of the low-level PWM control module selecting the transformer to be connected is synchronized with the process of the polarity reversal bridge flipping, which ensures the compatibility and coordination of the software and hardware levels and improves the switching efficiency of the power supply system.

[0143] Specifically, the specific process of coordinated synchronization between the process of the low-level PWM control module driving the transformer to connect to the power supply system and the process of the polarity reversal bridge driving the transformer to connect to the power supply system is as follows:

[0144] Determine the real-time collected grid voltage v grid Whether the polarity of changes, if the grid voltage v grid If the polarity of the input voltage changes, the phase angle θ is reset to zero, the phase angle increment Δθ is recalculated, and the polarity reversal bridge is driven to flip, thereby driving the corresponding transformer output end to connect to the power supply system;

[0145] If the grid voltage v grid If the polarity of does not change, the phase angle θ is accumulated, and the current given value is obtained by looking up the sine table according to the phase, thereby calculating the reference current i oref , according to the reference current i oref Calculate the dynamic duty cycle Δd, thereby determining the duty cycle D;

[0146] According to the result of the duty cycle D, a corresponding PWM signal is output to drive the corresponding transformer input end to connect to the power supply system.

[0147] According to the attached Figure 3As shown in the figure, when both the discrete transformer and the magnetic integrated transformer can meet the load power demand, different transformers have different working efficiencies in the power supply system when providing the same active power. Therefore, the high-level power management module makes intelligent decisions based on the load power demand, and then the low-level PWM control module is used to execute it, so that the power supply system can connect to the corresponding transformer on the basis of meeting the load demand to maximize the working efficiency of the power supply system.

[0148] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hierarchical control system for a high-efficiency discrete magnetic integrated power supply, characterized in that: It includes power supply circuit, high-level power management module and low-level PWM control module; The power supply circuit includes a transformer T1 and a transformer T2 connected in parallel, one of the two transformers is a magnetic integrated transformer, and the other transformer is a discrete transformer; the input ends of the transformer T1 and the transformer T2 are respectively driven by a switch tube and connected to the power supply system, and the output ends of the transformer T1 and the transformer T2 are respectively driven by a polarity reversal bridge and connected to the power supply system; The high-level power management module is used to make intelligent decisions based on the power required by the current load, select the corresponding transformer to connect to the power supply system, so that the power supply system can meet the load demand while maximizing efficiency, and generate the corresponding instruction set to be transmitted to the low-level PWM control module; The low-level PWM control module is used to adjust the duty cycle of the PWM signal to drive the corresponding switch tube, and connect the transformer selected by the high-level power management module to the power supply system, so that the power supply system can maximize the working efficiency while meeting the load demand.

2. The hierarchical control system of the high-efficiency discrete magnetic integrated power supply according to claim 1, characterized in that: The input voltage Vin of the power circuit is connected to the decoupling capacitor C decoup Connect to the input end of transformer T1 and transformer T2, the input end of transformer T1 is connected to switch tube Q1, and the output end is connected to the polarity reversal bridge through rectifier diode VD1; The input end of the transformer T2 is connected to a switch tube Q2, and the output end is connected to a polarity reversal bridge through a rectifier diode VD2. The output signal of the polarity reversal bridge passes through a filter and then outputs a grid-connected current i o , grid voltage v grid ; The switch tubes Q1 and Q2 are driven by PWM signals output by a low-level PWM control module.

3. The hierarchical control system of the high-efficiency discrete magnetic integrated power supply according to claim 2, characterized in that: An active clamping circuit 1 is configured at the switch tube Q1, and the active clamping circuit 1 includes a capacitor C1 and a switch tube Q3; an active clamping circuit 2 is configured at the switch tube Q2, and the active clamping circuit 2 includes a capacitor C2 and a switch tube Q4.

4. The hierarchical control system of the high-efficiency discrete magnetic integrated power supply according to claim 1, characterized in that: The polarity reversal bridge comprises thyristor T4, thyristor T5, MOS tube Q5, and MOS tube Q6. The polarity reversal bridge is connected to the grid according to the grid voltage v grid The polarity changes and switches on and off alternately. When the grid voltage v grid In the positive half cycle, transformer T1 and MOS tube Q6 are turned on, and transformer T1 is connected to the power supply system; when the grid voltage v grid In the negative half cycle, transformer T2 and MOS tube Q5 are turned on, and transformer T2 is connected to the power supply system.

5. The hierarchical control system of the high-efficiency discrete magnetic integrated power supply according to claim 1, characterized in that: The low-level PWM control module includes: ADC module, used to collect input voltage v in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid ; Phase-locked loop, used to convert the grid voltage v grid The frequency and phase are adjusted to be synchronized with the grid voltage to form a standard sinusoidal signal; PI regulator is used to adjust the grid current i o , reference current i oref Calculate the dynamic duty cycle Δd, the reference current i oref Related to the standard sinusoidal signal; Feedforward compensation module is used to adjust the grid voltage v grid and input voltage v in Calculate the steady-state duty cycle d; The current sharing control module is used to control the primary current i p1 、Flyback primary current i p2 Calculate the duty cycle correction term Δd'; The PWM signal generating module is used to output a corresponding PWM signal according to the calculated duty cycle D to drive the corresponding transformer to be connected to the power supply system, wherein the duty cycle D=d+Δd±Δd'.

6. The hierarchical control system of the high-efficiency discrete magnetic integrated power supply according to claim 5, characterized in that: The dynamic duty ratio Δd=(K p +K i / s)*(i oref -i o ), where the reference current i oref Produced by multiplying the standard sinusoidal signal by the current given value, (K p +K i / s) is the transfer function of the PI regulator; The steady-state duty cycle d=v grid / (v grid +nv in ), where n is the turns ratio between the primary and secondary sides of the transformer; The duty cycle correction term Δd'=(K p '+K i ' / s)*(i p1 -i p2 ), where (K p '+K i ' / s) is the transfer function of the PI regulator during the current sharing control process.

7. The hierarchical control system of the high-efficiency discrete magnetic integrated power supply according to claim 5, characterized in that: The process of the PWM signal driving the transformer input end to connect to the power supply system and the process of the polarity reversal bridge driving the transformer output end to connect to the power supply system are coordinated and synchronized with each other.

8. A control method for a high-efficiency discrete magnetic integrated power supply, characterized in that: A hierarchical control system suitable for a high-efficiency discrete magnetic integrated power supply as claimed in claim 1, comprising the following steps: Real-time monitoring of the power required by the load in the power supply system, the power including reactive power and active power; The high-level power management module selects the corresponding transformer to connect to the power supply system according to the power demand of the current load, and generates the corresponding instruction set to be transmitted to the low-level PWM control module; The low-level PWM control module adjusts the duty cycle of the PWM signal according to the instructions of the high-level power management module to drive the corresponding switch tube to conduct, so that the transformer selected by the high-level power management module is connected to the power supply system; The polarity reversal bridge in the power supply circuit is based on the grid voltage v grid The polarity of turns on the corresponding switch tube to connect the corresponding transformer; The low-level PWM control module monitors the grid-connected voltage v output by the power supply system in real time grid and grid current i o and feeds the data back to the high-level power management module to achieve dynamic adjustment; The process of the low-level PWM control module driving the transformer to access the power supply system is coordinated and synchronized with the process of the polarity reversal bridge driving the transformer to access the power supply system.

9. The control method of the high-efficiency discrete magnetic integrated power supply according to claim 8, characterized in that: The operation process of the low-level PWM control module is as follows: Acquisition signal: real-time acquisition of input voltage v in 、Flyback primary current i p1 、Flyback primary current i p2 , grid-connected current i o and grid voltage v grid ; Obtain a standard sinusoidal signal: grid Input into the phase-locked loop to generate a standard sinusoidal signal with the same frequency and phase as the grid voltage; Calculate the dynamic duty cycle Δd: Multiply the standard sinusoidal signal by the current given value to calculate the reference current i oref , and the grid-connected current i o With reference current i oref The error signal between the two generates a dynamic duty cycle Δd through the PI regulator. The transfer function of the PI regulator is (K p +K i / s), so the dynamic duty cycle Δd=(K p +K i / s)*(i oref -i o ); Calculate the steady-state duty cycle d: grid voltage v grid and input voltage v in The steady-state duty cycle d=v is obtained by the feedforward compensation module. grid / (v grid +nv in ), where n is the transformer primary-to-secondary turns ratio; Calculate the duty cycle correction term Δd': The flyback primary current i p1 、Flyback primary current i p2 PI regulation is performed, and the transfer function of the PI regulator for current sharing control is (K p '+K i ' / s), so the output duty cycle correction term Δd'=(K p '+K i ' / s)*(i p1 -i p2 ); Calculate the duty cycle D of the power supply system according to the dynamic duty cycle Δd, the steady-state duty cycle d, and the duty cycle correction term Δd', where the duty cycle D=d+Δd±Δd'; Output PWM signal: Output the corresponding PWM signal according to the calculated duty cycle D to drive the corresponding switch tube to conduct, so that the transformer selected by the high-level power management module is connected to the power supply system; Data feedback: Real-time monitoring of the grid-connected voltage v output by the power supply system grid and grid current i o and feeds the data back to the high-level power management module to achieve dynamic adjustment.

10. The control method of the high-efficiency discrete magnetic integrated power supply according to claim 8, characterized in that: The specific process of the coordinated synchronization between the process of the low-level PWM control module driving the transformer to access the power supply system and the process of the polarity reversal bridge driving the transformer to access the power supply system is as follows: Determine the real-time collected grid voltage v grid Whether the polarity of changes, if the grid voltage v grid If the polarity of the input voltage changes, the phase angle θ is reset to zero, the phase angle increment Δθ is recalculated, and the polarity reversal bridge is driven to flip, thereby driving the corresponding transformer output end to connect to the power supply system; If the grid voltage v grid If the polarity of does not change, the phase angle θ is accumulated, and the current given value is obtained by looking up the sine table according to the phase, thereby calculating the reference current i oref , according to the reference current i oref Calculate the dynamic duty cycle Δd, thereby determining the duty cycle D; According to the result of the duty cycle D, a corresponding PWM signal is output to drive the corresponding transformer input end to connect to the power supply system.

Images