Single-stage multi-path alternating current / direct current conversion circuit

Abstract

Provided in the present application is a single-stage multi-path alternating current / direct current conversion circuit. Said circuit uses three sets of switches to perform conduction switching of different lines, so as to achieve two input energy transfer modes a three-phase input line voltage mode and a phase voltage mode, thus solving the problem that the voltage stress of semiconductor devices is high when input line voltages are high, and solving the problem that when input line voltages are low, semiconductor devices have large conduction loss and reduced conversion efficiency. Additionally, the present application relates to a single-stage isolation circuit, and compared with two-stage isolation circuits, the single-stage isolation circuit can realize input power factor correction, electrical isolation and direct-current output buck-boost conversion, and has higher conversion efficiency.

Description

Single-stage multi-channel AC / DC conversion circuit

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 28, 2023, with application number 202311600025.0 and application name “Single-stage multi-channel AC / DC conversion circuit”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of power supply circuits, and in particular to a single-stage multi-channel AC / DC conversion circuit. Background Art

[0003] With the rapid development of electric vehicles, the demand for charging infrastructure is increasing. Currently, there are numerous circuit topologies for the charging modules in these facilities. For example, a two-stage solution is commonly used for three-phase input, but the overall conversion efficiency of this two-stage solution is relatively low. Therefore, achieving higher conversion efficiency for the circuits corresponding to charging modules is a pressing technical issue in this field.

[0004] Summary of the Invention

[0005] The present application provides a single-stage multi-channel AC / DC conversion circuit, which realizes the regulation of input current through a single-stage circuit, and simultaneously realizes power factor correction and input and output isolation, and has a higher conversion efficiency than a two-stage circuit.

[0006] The present application provides a single-stage multi-channel AC / DC conversion circuit, which includes: a three-phase circuit, wherein each phase circuit of the three-phase circuit includes a switching circuit, a rectifier circuit, a single-stage energy transfer circuit, and a filter circuit; the single-stage energy transfer circuit includes a transformer, an inverter circuit of the primary winding of the transformer, and an output rectifier circuit of the secondary winding of the transformer; the inverter circuit includes a DC blocking capacitor, an inductor, and a switch tube;

[0007] For each phase circuit, the first fixed terminal of the switching circuit is connected to the second port of the input voltage source, and the second fixed terminal of the switching circuit is connected to the first port of the input voltage source of another phase circuit other than the phase circuit, so that each phase circuit receives a different line voltage. The first input terminal and the second input terminal of the rectifier circuit are respectively connected to the first port of the input voltage source and the moving terminal of the switching circuit. The first output terminal and the second output terminal of the rectifier circuit are respectively connected to the first input terminal and the second input terminal of the single-stage energy transfer circuit. The first output terminal and the second output terminal of the single-stage energy transfer circuit are connected to the two ends of the filter circuit, and the three filter circuits in the three-phase circuit are connected in parallel.

[0008] The switch circuit is configured to control the conduction between the second fixed terminals and the first movable terminals of the three switch circuits in the three-phase circuit when the line voltage input to each phase circuit is not greater than a first preset voltage; and to control the conduction between the first fixed terminals and the first movable terminals of the three switch circuits when the line voltage input to each phase circuit is greater than the first preset voltage;

[0009] a rectifier circuit, configured to convert an input first AC signal into a first DC signal;

[0010] an inverter circuit, configured to convert the first DC signal into a second AC signal, wherein the current of the second AC signal is controlled by a switch in the inverter circuit;

[0011] a transformer for adjusting the voltage of the second AC signal; an output rectifier circuit for rectifying the AC signal output by the transformer to output a second DC signal;

[0012] a filtering circuit, configured to filter the second DC signal;

[0013] Among them, the switching tube of the inverter circuit in each phase circuit is controlled according to a control signal, the control signal is determined according to a first control result, the first control result is determined after loop control based on the deviation between the input current of each phase circuit and the corresponding input current control amount, and the input current control amount is determined by the control result determined after loop control based on the deviation between the current or voltage output by the single-stage multi-channel AC / DC conversion circuit and the external required current or required voltage.

[0014] It can be seen that the present application proposes a single-stage multi-channel AC / DC conversion circuit, which switches the conduction of different lines through three sets of switches to realize two input energy transmission modes: three-phase input line voltage and phase voltage. This solves the problem of high voltage stress of semiconductor devices when the input line voltage is high, and also solves the problem of large conduction loss of semiconductor devices and reduced conversion efficiency when the input line voltage is low. In addition, the intelligent input switching strategy of line voltage and phase voltage is combined to achieve a larger input voltage range and a larger output voltage gain range. At the same time, since the present application is a single-stage isolation circuit, compared with a two-stage isolation circuit, it can not only realize input power factor correction, electrical isolation and DC output buck-boost conversion, but also has higher conversion efficiency.

[0015] In a feasible example, the inverter circuit includes a DC blocking capacitor, an inductor, and a switching tube, and the output rectifier circuit includes a first diode; for each phase circuit, the first port of the inductor is connected to the first output end of the rectifier circuit, the second port of the inductor is connected to the input end of the switching tube and the first port of the DC blocking capacitor, the second port of the DC blocking capacitor is connected to the first port of the primary winding of the transformer, the second port of the primary winding of the transformer is connected to the output end of the switching tube and the second output end of the rectifier circuit, the first port of the secondary winding of the transformer is connected to the first port of the first diode, the second port of the first diode is connected to the first input end of the filter circuit, and the second port of the secondary winding of the transformer is connected to the second input end of the filter circuit.

[0016] In the present application, the above-mentioned single-stage energy transfer circuit can not only realize isolated energy transfer, but also realize power factor correction function by controlling the switch tube.

[0017] In a feasible example, the control signal driving times corresponding to the switch tubes in the three single-stage energy transfer circuits in the three-phase circuit are respectively spaced apart by one-third of the switching cycle.

[0018] In the present application, the output current ripple can be reduced by spacing the driving times of the control signals corresponding to the three switching tubes in the three-phase circuit by one-third of the switching cycle.

[0019] In a feasible example, each phase circuit further includes a single-stage energy transfer circuit, and the two single-stage energy transfer circuits in each phase circuit are connected in parallel.

[0020] In this application, by connecting a single-stage energy transfer circuit in parallel, not only the output current ripple can be reduced, but also the output power density can be improved.

[0021] In a feasible example, the control signal driving times corresponding to the switch tubes in the two single-stage energy transfer circuits in each phase circuit are separated by half a switching cycle.

[0022] In the present application, the output current ripple can be reduced by setting the driving time of the control signals corresponding to the two switching tubes in one phase to half a switching cycle.

[0023] In a feasible example, the input current control amount is determined based on the minimum value between the second control result and the third control result, the second control result is the control result determined after loop control of the current output by the single-stage multi-channel AC / DC conversion circuit and the external demand current, and the third control result is the control result determined after loop control of the voltage output by the single-stage multi-channel AC / DC conversion circuit and the external demand voltage.

[0024] In the present application, the output current and output voltage can be controlled respectively through output current loop control and output voltage loop control.

[0025] In a feasible example, the input current control amount is determined according to the minimum value between the second control result and the third control result, and the absolute value of the voltage input to each phase circuit.

[0026] In the present application, the absolute value of the voltage input to each phase circuit is introduced to achieve control of the input current waveform following the input voltage waveform.

[0027] In a possible example, the control signal is a pulse width modulation signal.

[0028] In a feasible example, the rectifier circuit includes a second diode, a third diode, a fourth diode, a fifth diode and a first filter capacitor; the rectifier circuit is used to convert alternating current into direct current; for each phase circuit, the first port of the second diode is connected to the first port of the input voltage source and the second port of the third diode, the first port of the third diode serves as the second output end of the rectifier circuit, and is connected to the first port of the fifth diode and the second port of the first filter capacitor, the second port of the second diode serves as the first output end of the rectifier circuit, and is connected to the second port of the fourth diode and the first port of the first filter capacitor, and the first port of the fourth diode is connected to the active end of the switching circuit and the second port of the fifth diode.

[0029] In a feasible example, the filtering circuit includes a second filter capacitor; for each phase circuit, the first port of the second filter capacitor serves as the first input end of the filtering circuit and is respectively connected to the first output ends of the three single-stage energy transfer circuits in the three-phase circuit, and the second port of the second filter capacitor serves as the second input end of the filtering circuit and is respectively connected to the second output ends of the three single-stage energy transfer circuits in the three-phase circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] FIG1 is a topological diagram of a single-stage multi-channel AC-DC conversion circuit provided in an embodiment of the present application;

[0032] FIG2 is a topological diagram of another single-stage multi-channel AC-DC conversion circuit provided in an embodiment of the present application;

[0033] FIG3 is a topological diagram of another single-stage multi-channel AC-DC conversion circuit provided in an embodiment of the present application;

[0034] FIG4 is a schematic diagram of a driving current waveform provided in an embodiment of the present application;

[0035] FIG5 is a control block diagram of a single-stage multi-channel AC / DC conversion circuit. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 are within the scope of protection of this application.

[0037] The terms "first," "second," and the like in the specification, claims, and drawings of this application are used to distinguish between different objects rather than to describe a specific order. In addition, the terms "include," "include," and "have," and any variations thereof, are intended to cover non-exclusive inclusions.

[0038] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0039] Please refer to Figure 1, which is a topological diagram of a single-stage multi-channel AC-DC conversion circuit provided in an embodiment of the present application. As shown in Figure 1, it includes input voltage sources Va, Vb and Vc corresponding to the three phases, switching circuits, rectifier circuits 101, 102 and 103, single-stage energy transfer circuits 111, 112 and 113, and filter circuits 121, 122 and 123. The single-stage energy transfer circuits 111, 112 and 113 respectively include a transformer, an inverter circuit of the primary winding of the transformer and an output rectifier circuit of the secondary winding of the transformer. The switching circuit is implemented by single-pole double-throw switches S1, S2 and S3. The switches S1, S2 and S3 include a moving end and a fixed end. The fixed ends include a first fixed end and a second fixed end, respectively, corresponding to port 1 and port 2 in the figure, respectively.

[0040] The moving end of switch S1 is connected to the second input end of rectifier circuit 101. The first input end of rectifier circuit 101 is connected to the first port of input voltage source Va and the second fixed end of switch S3. The first fixed end of switch S1 is connected to the second port of input voltage source Va, the second port of input voltage source Vb, the first fixed end of switch S2, the second port of input voltage source Vc, and the first fixed end of switch S3. The first port of input voltage source Vb is connected to the second fixed end of switch S1 and the first input end of rectifier circuit 102. The moving end of switch S2 is connected to the second input end of rectifier circuit 102, the first port of input voltage source Vc is connected to the second fixed end of switch S2 and the first input end of rectifier circuit 103. The moving end of switch S3 is connected to the second input end of rectifier circuit 103. N is point N of the three-phase AC input phase voltage.

[0041] The first output terminal and the second output terminal of the rectifier circuit 101 are respectively connected to the first input terminal and the second input terminal of the inverter circuit in the single-stage energy transfer circuit 111, and the first output terminal and the second output terminal of the output rectifier circuit in the single-stage energy transfer circuit 111 are connected to the two ends of the filter circuit 121; the first output terminal and the second output terminal of the rectifier circuit 102 are respectively connected to the first input terminal and the second input terminal of the inverter circuit in the single-stage energy transfer circuit 112, and the first output terminal and the second output terminal of the output rectifier circuit in the single-stage energy transfer circuit 112 are connected to the two ends of the filter circuit 122; the first output terminal and the second output terminal of the rectifier circuit 103 are respectively connected to the first input terminal and the second input terminal of the inverter circuit in the single-stage energy transfer circuit 113, and the first output terminal and the second output terminal of the output rectifier circuit in the single-stage energy transfer circuit 113 are connected to the two ends of the filter circuit 123; and the filter circuits 121, 122, and 123 are connected in parallel.

[0042] The rectifier circuits 101 , 102 and 103 are respectively used to convert a first AC signal inputted in each phase into a first DC signal. The first AC signal is determined according to the conduction state of the switches S1 , S2 and S3 .

[0043] Specifically, in the initial stage, the moving terminals of switches S1, S2, and S3 all contact the second fixed terminal, achieving conduction between the second fixed terminal and the moving terminal. At this time, the voltage signals corresponding to the first AC signal input to the circuit are the three-phase line voltages Vab, Vbc, and Vca. When the line voltage input to each phase circuit is greater than a first preset voltage, the moving terminals of switches S1, S2, and S3 all contact the first fixed terminal, achieving conduction between the first fixed terminal and the moving terminal. At this time, the voltage signals corresponding to the first AC signal input to the circuit are the three-phase line voltages Van, Vbn, and Vcn. Similarly, when the line voltage input to each phase circuit is no greater than the first preset voltage, the moving terminals of switches S1, S2, and S3 all contact the second fixed terminal again, achieving conduction between the second fixed terminal and the moving terminal. At this time, the voltage signals corresponding to the first AC signal input to the circuit are the three-phase line voltages Vab, Vbc, and Vca. Wherein, line voltage Vab = Van - Vbn, line voltage Vbc = Vbn - Vcn, and line voltage Vca = Vcn - Van.

[0044] The inverter circuits in the single-stage energy transfer circuits 111, 112 and 113 are respectively used to convert the first DC signals input by the rectifier circuits 101, 102 and 103 in each phase into second AC signals, wherein the current of the second AC signal is controlled by the switch tube in the inverter circuit.

[0045] The transformers in the single-stage energy transfer circuits 111, 112 and 113 are respectively used to adjust the voltage of the second AC signal input by the inverter circuit in each phase;

[0046] The output rectifier circuits in the single-stage energy transfer circuits 111 , 112 and 113 are respectively used to rectify the AC signal output by the transformer in each phase to output a second DC signal.

[0047] The filter circuits 121 , 122 and 123 are respectively used to filter the second DC signal output by the output rectifier circuit in each phase.

[0048] This circuit can achieve a wider input voltage range by switching between phase voltage input and line voltage input. And by controlling the conduction and disconnection of the switching tube in the inverter circuit to adjust the input current of each phase circuit, the power factor correction of the above circuit is achieved.

[0049] The single-stage multi-channel AC-DC conversion circuit is described in detail below:

[0050] Specifically, please refer to Figure 2, which is another single-stage multi-channel AC-DC conversion circuit topology diagram provided in an embodiment of the present application. As shown in Figure 2, it includes input voltage sources Va, Vb and Vc corresponding to the three phases, and single-pole double-throw switches S1, S2 and S3.

[0051] Rectifier circuit 101 includes diodes D11, D12, D13, D14, and filter capacitor Cr1; rectifier circuit 102 includes diodes D21, D22, D23, D24, and filter capacitor Cr2; and rectifier circuit 103 includes diodes D31, D32, D33, D34, and filter capacitor Cr3. The aforementioned diodes are rectifier diodes.

[0052] The single-stage energy transfer circuit 111 includes a transformer T1, a first inverter circuit for the primary winding of the transformer T1, and a first output rectifier circuit for the secondary winding of the transformer T1. The first inverter circuit includes a filter inductor Lf1, a switch Q1, and a DC blocking capacitor C1, and the first output rectifier circuit includes a diode D1. The single-stage energy transfer circuit 112 includes a transformer T3, a second inverter circuit for the primary winding of the transformer T3, and a second output rectifier circuit for the secondary winding of the transformer T3. The second inverter circuit includes a filter inductor Lf3, a switch Q3, and a DC blocking capacitor C3, and the second output rectifier circuit includes a diode D3. The single-stage energy transfer circuit 113 includes a transformer T5, a third inverter circuit for the primary winding of the transformer T5, and a third output rectifier circuit for the secondary winding of the transformer T1. The third inverter circuit includes a filter inductor Lf5, a switch Q5, and a DC blocking capacitor C5, and the third output rectifier circuit includes a diode D5. Among them, filter inductors Lf1, Lf3, and Lf5 are all input differential mode filter inductors, DC blocking capacitors C1, C3, and C5 are all high-frequency DC blocking capacitors, and diodes D1, D3, and D5 are secondary side output rectifier diodes.

[0053] The filter circuit 121 includes a filter capacitor Co1. The filter circuit 122 includes a filter capacitor Co2. The filter circuit 123 includes a filter capacitor Co3. The output end of the filter circuit 122 serves as the output of the single-stage multi-channel AC / DC conversion circuit.

[0054] The following describes the connection relationship of the above devices:

[0055] For the first phase: the first port of diode D11 is connected to the first port of input voltage source Va and the second port of diode D12. The first port of diode D12 is connected to the first port of diode D14, the second port of filter capacitor Cr1, the output of switch Q1, and the second port of the primary winding of transformer T1. The second port of diode D11 is connected to the second port of diode D13, the first port of filter capacitor Cr1, and the first port of filter inductor Lf1. The first port of diode D13 is connected to the active terminal of switch S1 and the second port of diode D14. The second port of filter inductor Lf1 is connected to the input of switch Q1 and the first port of DC blocking capacitor C1. The second port of DC blocking capacitor C1 is connected to the first port of the primary winding of transformer T1. The first port of the secondary winding of transformer T1 is connected to the first port of diode D1. The second port of diode D1 is connected to the first port of filter capacitor Co1. The second port of the secondary winding of transformer T1 is connected to the second port of filter capacitor Co1.

[0056] For the second phase: the first port of diode D21 is connected to the first port of input voltage source Vb and the second port of diode D22. The first port of diode D22 is connected to the first port of diode D24, the second port of filter capacitor Cr2, the output of switch Q3, and the second port of the primary winding of transformer T3. The second port of diode D21 is connected to the second port of diode D23, the first port of filter capacitor Cr2, and the first port of filter inductor Lf3. The first port of diode D23 is connected to the active terminal of switch S2 and the second port of diode D24. The second port of filter inductor Lf3 is connected to the input of switch Q3 and the first port of DC blocking capacitor C3. The second port of DC blocking capacitor C3 is connected to the first port of the primary winding of transformer T3. The first port of the secondary winding of transformer T3 is connected to the first port of diode D3. The second port of diode D3 is connected to the first port of filter capacitor Co2. The second port of the secondary winding of transformer T3 is connected to the second port of filter capacitor Co2.

[0057] For the third phase: the first port of diode D31 is connected to the first port of input voltage source Vc and the second port of diode D32. The first port of diode D32 is connected to the first port of diode D34, the second port of filter capacitor Cr3, the output of switch Q5, and the second port of the primary winding of transformer T5. The second port of diode D31 is connected to the second port of diode D33, the first port of filter capacitor Cr3, and the first port of filter inductor Lf5. The first port of diode D33 is connected to the active terminal of switch S3 and the second port of diode D34. The second port of filter inductor Lf5 is connected to the input of switch Q5 and the first port of DC blocking capacitor C5. The second port of DC blocking capacitor C5 is connected to the first port of the primary winding of transformer T5. The first port of the secondary winding of transformer T5 is connected to the first port of diode D5. The second port of diode D5 is connected to the first port of filter capacitor Co3. The second port of the secondary winding of transformer T5 is connected to the second port of filter capacitor Co3.

[0058] The first port of filter capacitor Co1 is connected to the first port of filter capacitor Co2 and the first port of filter capacitor Co3. The second port of filter capacitor Co1 is connected to the second port of filter capacitor Co2 and the second port of filter capacitor Co3. The connection relationship between input voltage sources Va, Vb, and Vc, and single-pole double-throw switches S1, S2, and S3 has been previously described and will not be repeated here.

[0059] When the line voltage input to each phase circuit is no greater than a first preset voltage, the active terminals of the three single-pole double-throw switches S1, S2, and S3 contact the second fixed terminal, achieving conduction between the second fixed terminal and the active terminal. At this point, the circuit input voltage corresponds to the three-phase line voltages Vab, Vbc, and Vca. The voltage stress of switches Q1, Q3, and Q5, as well as diodes D1, D3, and D5, depends on the peak input line voltage and the output power. A higher peak input line voltage increases semiconductor device stress. Under the same input line voltage, a higher output power increases the duty cycle of switches Q1, Q3, and Q5. Consequently, the voltage stress across the terminals of switches Q1, Q3, and Q5 increases after they are turned off.

[0060] Therefore, when the input line voltage is high, the active terminals of the three single-pole double-throw switches S1, S2, and S3 are intelligently connected to the first fixed terminal, achieving conduction between the first fixed terminal and the active terminal. At this time, the circuit input voltage corresponds to the three-phase voltages Van, Vbn, and Vcn. The voltage stress on switches Q1, Q3, and Q5 and diodes D1, D3, and D5 depends on the peak input phase voltage and the output power. Because the peak input phase voltage is much lower than the peak input line voltage, the stress on semiconductor devices is reduced, and the switching losses of the power module are reduced. Even if the output power increases, the voltage stress on switches Q1, Q3, and Q5 and diodes D1, D3, and D5 remains within a safe range.

[0061] When the circuit input voltage corresponds to the phase voltage, the input current for transmitting power is also the phase current. This increases the current flowing through the main power components of the transformer primary winding (such as switches Q1, Q3, and Q5), leading to increased conduction losses in these components. Therefore, when the line voltage (determined by the difference between the two-phase voltages) is low, the circuit's conversion efficiency is low when the input voltage is the phase voltage. Therefore, when the line voltage is low, the active terminals of the three single-pole double-throw switches (S1, S2, and S3) are all connected to the second fixed terminal.

[0062] The first preset voltage may be determined according to the voltage stress of the main power devices (such as the switching tubes Q1 , Q3 , and Q5 ).

[0063] The circuit also achieves power factor correction by controlling the on and off switching transistors in the single-stage energy transfer circuit to adjust the input current of each phase. When switches Q1, Q3, and Q5 are off, energy is transferred to the output side via transformers T1, T3, and T5. When switches Q1, Q3, and Q5 are on, the transformer primary winding undergoes magnetic reset, and energy transfer from the primary winding to the secondary winding ceases.

[0064] The switching tubes Q1, Q3, and Q5 are controlled to be turned on and off by a control signal. The control signal can be a pulse width modulation (PWM) signal. The duty cycle corresponding to the control signal can be determined by performing loop control (current loop) based on the deviation between the input current of each phase circuit and the corresponding input current control amount. The input current control amount is determined based on the absolute value of the voltage input to each phase circuit and the fourth control result. The fourth control result is the second control result and the third control result. The second control result is the control result determined by performing loop control (current loop) between the current output by the single-stage multi-channel AC / DC conversion circuit and the external demand current. The third control result is the control result determined by performing loop control (voltage loop) between the voltage output by the single-stage multi-channel AC / DC conversion circuit and the external demand voltage. The loop control includes proportional integral controller (PI) control or proportional integral differential (PID) control.

[0065] The switching transistors can be triodes or metal-oxide-semiconductor field-effect transistors (MOSFETs). For example, when the switching transistors are N-channel MOS transistors, the input terminal of the switching transistor corresponds to the drain of the MOS transistor, the output terminal of the switching transistor corresponds to the source of the MOS transistor, and the control signal controls the switching transistor via the gate of the MOS transistor. Furthermore, the switching cycles of the control signals corresponding to the switching transistors Q1, Q3, and Q5 are the same, and the driving times are separated by one-third of the switching cycle. In other words, the transmission phases of the control signals corresponding to Q1, Q3, and Q5 are staggered by 120°.

[0066] In addition, each phase circuit may also include an identical single-stage energy transfer circuit, and the two single-stage energy transfer circuits in each phase circuit are connected in parallel. This is illustrated below with reference to FIG3 :

[0067] Please refer to Figure 3, which is a topological diagram of another single-stage multi-channel AC-DC conversion circuit provided in an embodiment of the present application. As shown in Figure 3, compared with Figure 2, the single-stage multi-channel AC-DC conversion circuit further includes transformers T2, T4, T6, switches Q2, Q4, Q6, filter inductors Lf2, Lf4, Lf6, DC blocking capacitors C2, C4, C6, and diodes D2, D4, D6.

[0068] The following describes the connection relationship of the above devices:

[0069] The first port of the filter inductor Lf2 is connected to the first port of the filter inductor Lf1, the second port of the filter inductor Lf2 is connected to the input end of the switch tube Q2 and the first port of the DC blocking capacitor C2, the second port of the DC blocking capacitor C2 is connected to the first port of the primary winding of the transformer T2, the second port of the primary winding of the transformer T2 is connected to the output end of the switch tube Q2 and the second port of the primary winding of the transformer T1, the first port of the secondary winding of the transformer T2 is connected to the first port of the diode D2, the second port of the diode D2 is connected to the second port of the diode D1 and the first port of the filter capacitor Co1, and the second port of the secondary winding of the transformer T2 is connected to the second port of the secondary winding of the transformer T1 and the second port of the filter capacitor Co1.

[0070] The first port of the filter inductor Lf4 is connected to the first port of the filter inductor Lf3, the second port of the filter inductor Lf4 is connected to the input end of the switch tube Q4 and the first port of the DC blocking capacitor C4, the second port of the DC blocking capacitor C4 is connected to the first port of the primary winding of the transformer T4, the second port of the primary winding of the transformer T4 is connected to the output end of the switch tube Q4 and the second port of the primary winding of the transformer T3, the first port of the secondary winding of the transformer T4 is connected to the first port of the diode D4, the second port of the diode D4 is connected to the second port of the diode D3 and the first port of the filter capacitor Co2, and the second port of the secondary winding of the transformer T4 is connected to the second port of the secondary winding of the transformer T3 and the second port of the filter capacitor Co2.

[0071] The first port of the filter inductor Lf6 is connected to the first port of the filter inductor Lf5, the second port of the filter inductor Lf6 is connected to the input end of the switch tube Q6 and the first port of the DC blocking capacitor C6, the second port of the DC blocking capacitor C6 is connected to the first port of the primary winding of the transformer T6, the second port of the primary winding of the transformer T6 is connected to the output end of the switch tube Q6 and the second port of the primary winding of the transformer T5, the first port of the secondary winding of the transformer T6 is connected to the first port of the diode D6, the second port of the diode D6 is connected to the second port of the diode D5 and the first port of the filter capacitor Co3, and the second port of the secondary winding of the transformer T6 is connected to the second port of the secondary winding of the transformer T5 and the second port of the filter capacitor Co3.

[0072] The following describes the conduction status of the switch tube of one of the three phases in conjunction with FIG4 :

[0073] Please refer to Figure 4, which is a schematic diagram of a drive current waveform provided by an embodiment of the present application. As shown in Figure 4, it includes waveform Vgs1 of the control signal for switch Q1, waveform Vgs2 of the control signal for switch Q2, current waveform iLf1 of inductor Lf1, current waveform iLf2 of inductor Lf2, and overall circuit output current waveform io. The control signals for switch Q1 and switch Q2 correspond to the same switching cycle, and the driving time between the two is half a switching cycle. In other words, the control signals for switch Q1 and switch Q2 are phase-shifted by 180°.

[0074] When switch Q1 is turned on, the AC input voltage is superimposed on the filter inductor Lf1, causing the current in filter inductor Lf1 to increase. At this time, the voltage across DC blocking capacitor C1 is reversely superimposed on the primary winding of transformer T1. As transformer T1 undergoes magnetic reset, DC blocking capacitor C1 itself discharges, placing diode D1 in a reverse blocking state. When switch Q1 is turned off, the current in filter inductor Lf1 decreases, and the inductor current flows through DC blocking capacitor C1 and the primary winding of transformer T1, transferring energy to the secondary winding of transformer T1 and charging DC blocking capacitor C1. At this point, diode D1 is in a forward conducting state.

[0075] Similarly, when switch Q2 is turned on, the AC input voltage is superimposed on the filter inductor Lf2, causing the current in filter inductor Lf2 to increase. At this time, the voltage across DC blocking capacitor C2 is reversely superimposed on the primary winding of transformer T2. While transformer T2 is magnetically reset, DC blocking capacitor C2 itself discharges, and diode D2 is now in a reverse blocking state. When switch Q2 is turned off, the current in filter inductor Lf2 decreases, and the inductor current transfers energy to the secondary winding of transformer T2 through DC blocking capacitor C2 and the primary winding of transformer T2, while also charging DC blocking capacitor C2. At this time, diode D2 is in a forward conducting state.

[0076] When the control signals for switches Q1 and Q2 are staggered by 180°, the output current is the sum of the output currents of the two diodes, as shown in Figure 4. The output current ripple period is twice the switching frequency period, significantly reducing the current ripple. When the control signals for the switches in the three-phase circuit are staggered by another 120°, the output current ripple is further reduced, significantly reducing the number of output filter capacitors and improving module power density, while also enhancing the module's output performance and service life.

[0077] The determination of the control signal of the above-mentioned switch tube is specifically described below with reference to FIG5 :

[0078] Please refer to Figure 5, which is a control block diagram of a single-stage, multi-channel AC / DC converter circuit. As shown in Figure 5, the output voltage Vo and output current io of the single-stage, multi-channel AC / DC converter circuit are sampled, and the output voltage set value (demand voltage) Voref and the output current set value (demand current) Ioref are determined based on external load requirements. The output voltage Vo and the output voltage set value Voref are input into the output voltage loop for calculation, resulting in the output voltage loop output result Vpi. The output current io and the output current set value Ioref are input into the output current loop for calculation, resulting in the output current loop result Ipi. The smaller of the output voltage loop result and the output current loop result is taken to obtain the final output loop control result Minpi. This allows voltage control and current control of the aforementioned circuit to be achieved, respectively.

[0079] The conduction state of switches S1, S2, and S3 is switched according to the size of the three-phase input line voltage. When the line voltage is at a higher value, switches S1, S2, and S3 are switched to conduction between the moving end and the first fixed end. At this time, the three-phase phase voltages Van, Vbn, and Vcn are taken to obtain the absolute values ​​of the voltage samples of the three-phase input phase voltages |Vac1|, |Vac2|, and |Vac3|; when the line voltage is at a lower value, switches S1, S2, and S3 are switched to conduction between the moving end and the second fixed end. At this time, the three-phase line voltages Vab, Vbc, and Vca are taken to obtain the absolute values ​​of the voltage samples of the three-phase input line voltages |Vac1|, |Vac2|, and |Vac3|.

[0080] The absolute values ​​of the sampled three-phase input AC voltage signals, |Vac1|, |Vac2|, and |Vac3|, are multiplied by the loop output Minpi to obtain the current reference values ​​Iac1ref, Iac2ref, and Iac3ref, respectively. At this point, the first-phase input current is sampled to obtain the first-phase input current Iac1. The first-phase input current Iac1 and the corresponding first-phase current reference value Iac1ref are input into the first input current loop for calculation, resulting in the duty cycle DR1 of the control signal for the switch in the single-stage energy transfer circuit in that phase circuit.

[0081] The second-phase input current Iac2 is obtained by sampling the second-phase input current. This second-phase input current Iac2 and the corresponding second-phase current reference value Iac2ref are input into the second input current loop for calculation to obtain the duty cycle DR2 of the control signal for the switch in the single-stage energy transfer circuit in the phase circuit. The third-phase input current Iac3 is obtained by sampling the third-phase input current. This third-phase input current Iac3 and the corresponding third-phase current reference value Iac3ref are input into the third input current loop for calculation to obtain the duty cycle DR3 of the control signal for the switch in the single-stage energy transfer circuit in the phase circuit.

[0082] Duty cycles DR1, DR2, and DR3 are input into the PWM generation design unit to generate pulse-width modulated signals PWM1, PWM2, and PWM3 corresponding to switches Q1, Q3, and Q5, respectively. When two single-stage energy transfer circuits are present in each phase, a six-way interleaved generation design is performed on the pulse-width modulated signals PWM1, PWM2, and PWM3 to generate control signals SQ1, SQ2, SQ3, SQ4, SQ5, and SQ6 corresponding to switches Q1, Q2, Q3, Q4, Q5, and Q6, respectively. The generation phases of control signals SQ1 and SQ2 are staggered by 180°, the generation phases of control signals SQ3 and SQ4 are staggered by 180°, and the generation phases of control signals SQ5 and SQ6 are staggered by 180°. Furthermore, the generation phases of control signals SQ1, SQ3, and SQ5 are staggered by 120°. This minimizes output current ripple.

[0083] This application proposes a single-stage multi-channel AC / DC conversion circuit, which realizes two input energy transmission modes of three-phase input line voltage and phase voltage through three sets of single-pole double-throw switches. It solves the problem of high voltage stress of semiconductor devices when the input line voltage is high, and also solves the problem of large conduction loss and reduced conversion efficiency of semiconductor devices when the input line voltage is low. At the same time, combined with the intelligent input switching strategy of line voltage and phase voltage, a larger input voltage range and a larger output voltage gain range can be achieved. At the same time, since this application is a single-stage isolation circuit, compared with a two-stage isolation circuit, it can not only realize input power factor correction, electrical isolation and DC output buck-boost conversion, but also has higher conversion efficiency.

[0084] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0085] The above is a detailed introduction to the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A single-stage multi-channel AC / DC conversion circuit, characterized in that: The single-stage multi-channel AC / DC conversion circuit includes a three-phase circuit, wherein each phase circuit of the three-phase circuit includes a switch circuit, a rectifier circuit, a single-stage energy transfer circuit and a filter circuit, and the single-stage energy transfer circuit includes a transformer, an inverter circuit of the primary winding of the transformer and an output rectifier circuit of the secondary winding of the transformer; For each phase circuit, the first fixed end of the switch circuit is connected to the second port of the input voltage source, and the second fixed end of the switch circuit is connected to the first port of the input voltage source in another phase circuit outside the phase circuit, so that different line voltages are input to each phase circuit respectively, the first input end and the second input end of the rectifier circuit are respectively connected to the first port of the input voltage source and the moving end of the switch circuit, the first output end and the second output end of the rectifier circuit are respectively connected to the first input end and the second input end of the single-stage energy transfer circuit, the first output end and the second output end of the single-stage energy transfer circuit are connected to the two ends of the filter circuit, and the three filter circuits in the three-phase circuit are connected in parallel; The switch circuit is used to control the conduction between the second fixed end and the first movable end of the three switch circuits in the three-phase circuit when the line voltage input to each phase circuit is not greater than the first preset voltage; and to control the conduction between the first fixed end and the first movable end of the three switch circuits when the line voltage input to each phase circuit is greater than the first preset voltage; The rectifier circuit is used to convert the input first AC signal into a first DC signal; The inverter circuit is used to convert the first DC signal into a second AC signal, wherein the current of the second AC signal is controlled by a switch in the inverter circuit; The transformer is used to adjust the voltage of the second AC signal; The output rectifier circuit is used to rectify the AC signal output by the transformer to output a second DC signal; The filtering circuit is used to filter the second DC signal; Among them, the switch tube of the inverter circuit in each phase circuit is controlled according to a control signal, and the control signal is determined according to a first control result, and the first control result is determined after loop control based on a deviation between an input current of each phase circuit and a corresponding input current control amount, and the input current control amount is determined by a control result determined after loop control based on a deviation between a current or voltage output by the single-stage multi-channel AC / DC conversion circuit and an external required current or required voltage.

2. The single-stage multi-channel AC / DC conversion circuit according to claim 1, characterized in that: The inverter circuit includes a DC blocking capacitor, an inductor, and a switch tube, and the output rectifier circuit includes a first diode; For each phase circuit, the first port of the inductor is connected to the first output end of the rectifier circuit, the second port of the inductor is connected to the input end of the switch tube and the first port of the DC blocking capacitor, the second port of the DC blocking capacitor is connected to the first port of the primary winding of the transformer, the second port of the primary winding of the transformer is connected to the output end of the switch tube and the second output end of the rectifier circuit, the first port of the secondary winding of the transformer is connected to the first port of the first diode, the second port of the first diode is connected to the first input end of the filter circuit, and the second port of the secondary winding of the transformer is connected to the second input end of the filter circuit.

3. The single-stage multi-channel AC / DC conversion circuit according to claim 1 or 2, characterized in that: The control signal driving times corresponding to the switch tubes in the three single-stage energy transfer circuits in the three-phase circuit are respectively spaced apart by one third of the switching cycle.

4. The single-stage multi-channel AC / DC conversion circuit according to claim 1 or 2, characterized in that: Each phase circuit also includes a single-stage energy transfer circuit, and the two single-stage energy transfer circuits in each phase circuit are connected in parallel.

5. The single-stage multi-channel AC / DC conversion circuit according to claim 4, characterized in that: The control signal driving times corresponding to the switch tubes in the two single-stage energy transfer circuits in each phase circuit are separated by half a switching cycle.

6. The single-stage multi-channel AC-DC conversion circuit according to claim 1 or 2, characterized in that: The input current control amount is determined based on the minimum value between the second control result and the third control result, the second control result is determined after loop control between the current output by the single-stage multi-channel AC / DC conversion circuit and the external required current, and the third control result is determined after loop control between the voltage output by the single-stage multi-channel AC / DC conversion circuit and the external required voltage.

7. The single-stage multi-channel AC / DC conversion circuit according to claim 6, characterized in that: The input current control amount is determined according to the minimum value between the second control result and the third control result, and the absolute value of the voltage input to the circuit of each phase.

8. The single-stage multi-channel AC-DC conversion circuit according to claim 1 or 2, characterized in that: The rectifier circuit includes a second diode, a third diode, a fourth diode, a fifth diode and a first filter capacitor; For each phase circuit, the first port of the second diode is connected to the first port of the input voltage source and the second port of the third diode, the first port of the third diode serves as the second output end of the rectifier circuit, and is connected to the first port of the fifth diode and the second port of the first filter capacitor, the second port of the second diode serves as the first output end of the rectifier circuit, and is connected to the second port of the fourth diode and the first port of the first filter capacitor, and the first port of the fourth diode is connected to the active end of the switch circuit and the second port of the fifth diode.

9. The single-stage multi-channel AC-DC conversion circuit according to claim 1 or 2, characterized in that: The filtering circuit includes a second filtering capacitor; For each phase circuit, the first port of the second filter capacitor serves as the first input end of the filter circuit and is respectively connected to the first output ends of the three single-stage energy transfer circuits in the three-phase circuit; the second port of the second filter capacitor serves as the second input end of the filter circuit and is respectively connected to the second output ends of the three single-stage energy transfer circuits in the three-phase circuit.

10. The single-stage multi-channel AC-DC conversion circuit according to claim 1 or 2, characterized in that: The control signal is a pulse width modulation signal.

Images