Single-phase high-frequency rectifier with clamping circuit and modulation method thereof

Abstract

The invention provides a single-phase high-frequency rectifier with a clamping circuit and a modulation method thereof, and relates to the field of rectifiers, and the single-phase high-frequency rectifier comprises a matrix converter, an active clamping circuit and a full-bridge rectifier. The matrix converter is used for converting a power frequency alternating current signal into a high-frequency alternating current signal; the active clamping circuit is a full-bridge circuit, and the active clamping circuit is used for eliminating leakage inductance of the high-frequency transformer and resonance voltage overshoot of a parasitic capacitor of a switching tube and is matched with the matrix converter to complete safe commutation of inductive current; the active clamping circuit is connected in parallel with the output of the matrix converter; the full-bridge rectifier comprises four MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors), the input end of the full-bridge rectifier is connected with the preceding-stage matrix converter and the active clamping circuit through the high-frequency transformer, and the output end of the full-bridge rectifier is connected with the filter capacitor and the resistor in parallel; the full-bridge rectifier is used for converting the high-frequency alternating-current signal into a direct-current signal. According to the technical scheme, the problems of voltage spike and resonance existing in a rectifier in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of rectifiers, and more specifically to a single-phase high-frequency rectifier with clamping circuit and its modulation method. Background Technology

[0002] In traditional rectification technology, rectifiers are mainly classified into non-isolated rectifiers and isolated rectifiers based on the presence or absence of high-frequency transformer electrical isolation. Non-isolated rectifiers are widely used due to their small size, high efficiency, and mature technology; however, their lack of electrical isolation limits their application in situations with high safety requirements. Isolated rectifiers, by achieving electrical isolation in power transmission, improve the safety of the entire power system. Isolated rectifiers can be further divided into power frequency isolated rectifiers and high-frequency isolated rectifiers based on the type of high-frequency transformer used.

[0003] Compared to AC / DC converters with power frequency isolation, traditional high-frequency isolated converters offer significant advantages in terms of size, weight optimization, and noise control, but they cannot achieve bidirectional power transfer and suffer from low system reliability. In contrast, high-frequency isolated AC / DC conversion systems employing matrix converter topologies demonstrate a breakthrough technological advancement, enabling bidirectional free flow of energy and exhibiting extremely high system stability.

[0004] A major problem faced by matrix converter-type high-frequency isolation rectifiers in practical applications is the severe voltage spikes and resonance issues on the AC side of the high-frequency transformer. This is mainly caused by two factors: First, the filter inductor current cannot achieve safe commutation. Due to the extremely narrow high-frequency commutation time window, when the power switch operates, the inductor's stored energy cannot be released in time through an effective freewheeling path, resulting in significant voltage spikes on the primary winding of the high-frequency transformer. Second, the resonance effect between the leakage inductance of the high-frequency transformer and the parasitic capacitance of the switch causes distortion of the output voltage waveform.

[0005] Therefore, there is a need for a high-frequency chain single-phase matrix rectifier with clamping circuit and its modulation method that can eliminate voltage spikes and improve system safety and reliability. Summary of the Invention

[0006] The main objective of this invention is to provide a single-phase high-frequency rectifier with clamping circuit and its modulation method to solve the problems of voltage spikes and resonance in existing rectifiers.

[0007] To achieve the above objectives, this invention provides a single-phase high-frequency rectifier with a clamping circuit, characterized in that it comprises: a matrix converter, an active clamping circuit, and a full-bridge rectifier; the matrix converter includes two bridge arms, each bridge arm including: two pairs of bidirectional power switches, each pair of bidirectional power switches being composed of two N-type anti-series power MOSFETs with a common source; the matrix converter is used to convert power frequency AC signals into high-frequency AC signals; the active clamping circuit is a full-bridge circuit, including: four MOSFETs and a clamping capacitor, the active clamping circuit is used to eliminate the resonant voltage overshoot caused by the leakage inductance of the high-frequency transformer and the parasitic capacitance of the switching transistors, and cooperates with the matrix converter to complete the safe commutation of the inductor current; the active clamping circuit is connected in parallel with the output of the matrix converter; the full-bridge rectifier includes: four MOSFETs, the input terminal of the full-bridge rectifier is connected to the preceding matrix converter and active clamping circuit through a high-frequency transformer, and the output terminal of the full-bridge rectifier is connected in parallel with a filter capacitor and a resistor; the full-bridge rectifier is used to convert high-frequency AC signals into DC signals.

[0008] Furthermore, the two bridge arms of the matrix converter are the fifth bridge arm and the sixth bridge arm. The two bridge arms are completely identical. The sources of the fifth master MOSFET S5 and the fifth slave MOSFET S5' in the fifth bridge arm are connected, the sources of the sixth master MOSFET S6 and the sixth slave MOSFET S6' in the fifth bridge arm are connected, and the drain of the fifth slave MOSFET S5' in the fifth bridge arm is connected to the drain of the sixth master MOSFET S6 in the fifth bridge arm.

[0009] Furthermore, the matrix converter also includes: an AC power supply V AC and grid-side filter inductor L f The positive terminal of the AC power supply is connected to the mains-side filter inductor L. f Then, it is connected to the drain of the fifth slave MOSFET S5' and the drain of the sixth master MOSFET S6; the negative terminal of the AC power supply is connected to the drain of the seventh slave MOSFET S7' and the drain of the eighth master MOSFET S8 of the sixth bridge arm.

[0010] Furthermore, the active clamping circuit includes two bridge arms, a third bridge arm and a fourth bridge arm. The third bridge arm and the fourth bridge arm are identical, and the third switch S of the fourth bridge arm... C3 The source and the fourth switch S C4 The drains of the seventh main MOSFET S7 of the sixth bridge arm, the drain of the fifth main MOSFET S5, and the first switch S7 of the third bridge arm are connected; C1 The drains of the sixth bridge arm are connected to the drains of the eighth slave MOSFET S8', the drain of the sixth slave MOSFET S6', and the eighth switch S. C4 The drains are connected; the active clamping circuit also includes a clamping capacitor C. CLClamping capacitor C CL One end is connected to the first switching transistor S C1 The drain of the third switch S in the fourth bridge arm C3 The drain, clamping capacitor C CL The other end is connected to the second switch S of the third bridge arm. C2 The drain and the fourth switch S C4 The drain electrode.

[0011] Furthermore, the full-bridge rectifier includes: a high-frequency transformer, a first bridge arm, and a second bridge arm. The first and second bridge arms are identical, and also identical to the third and fourth bridge arms. One end of the primary side of the high-frequency transformer is connected to the drain of the seventh main MOSFET S7 and the drain of the fifth main MOSFET S5, and the other end is connected to the drain of the eighth slave MOSFET S8' and the drain of the sixth slave MOSFET S6'. One end of the secondary side of the high-frequency transformer is connected to the drain of the fourth MOSFET S4 of the second bridge arm and the source of the third MOSFET S3 of the second bridge arm, and the other end is connected to the source of the first MOSFET S1 of the first bridge arm and the drain of the second MOSFET S2 of the first bridge arm. The full-bridge rectifier includes resistors R and filter capacitors C. d The first and second bridge arms are connected in parallel.

[0012] This invention also provides a modulation method for a single-phase high-frequency rectifier with clamping circuit, using a sawtooth wave as the carrier wave and a modulation wave u mw With carrier u cw The intersection of the rising edges marks the switching point of the first MOSFET S1. The drive signal of the second MOSFET S2 is complementary to the drive signal of the first MOSFET S1; modulation wave -u mw With carrier u cw The intersection of the rising edges is the switching point of the third MOSFET S3. The drive signal of the fourth MOSFET S4 is complementary to the drive signal of the third MOSFET S3. A dead time is added between the PWM signals of the first MOSFET S1 and the second MOSFET S2, the third MOSFET S3 and the fourth MOSFET S4.

[0013] A modulation method for a single-phase high-frequency rectifier with clamping circuit, specifically including the following steps:

[0014] S1 will modulate the wave -u mw With sawtooth wave carrier u cw The intersection of the rising edges is defined as time t0. Before time t0, in the active clamping circuit on the primary side of the high-frequency transformer, the second switching transistor S... C2 and the fourth switch S C4 parasitic diode D C4When in the conducting state, it represents the reverse current i on the primary side of the high-frequency transformer. C Provides a freewheeling path; on the secondary side of the high-frequency transformer, the secondary current i of the high-frequency transformer... A When the voltage is less than 0, the parasitic diode D3 of the first MOSFET S1 and the third MOSFET S3 remains in the conducting state, and the secondary output voltage of the high-frequency transformer is v. AB It is 0.

[0015] In phase S2, t0-t1, time t0 plus a certain dead time equals time t1. Before time t0, the parasitic diode D3 of the third MOSFET S3 is turned on, and at time t0, the third MOSFET S3 achieves zero-voltage turn-off. After the third MOSFET S3 turns off, the secondary circuit of the high-frequency transformer still forms a loop through the parasitic diode D3 of the first MOSFET S1 and the third MOSFET S3. The secondary output voltage v of the high-frequency transformer... AB The value remains at 0; the second switch S C2 Before the fourth MOSFET S4 turns on, i.e., at time t1, zero-voltage turn-off is completed; the second switch S C2 After being turned off, the clamping capacitor C is used during the t0-t1 phase. CL The circuit begins charging, and the clamping circuit current is i. ′ C =i C +i LF , where i ′ C i is the clamping circuit current. C i is the primary current of the high-frequency transformer. LF AC side inductor current; clamping capacitor C CL The voltage across the two ends is Where t is the current time; at time t1, the primary input voltage v of the high-frequency transformer is... CD The voltage v on the secondary side of the high-frequency transformer is raised to NE. AB It was elevated to E.

[0016] Furthermore, it also includes the following steps:

[0017] S3, during the t1-t2 phase, time t3 minus a certain dead time equals time t2, the modulated wave u mw With sawtooth wave carrier u cw The intersection of the rising edges is at time t3. At time t1, the fourth MOSFET S4 is turned on in zero-current mode (ZCS), and simultaneously, the parasitic diode D4 of the fourth MOSFET S4 is naturally turned on. Since the first switching transistor S4... C1 parasitic diode D C1 Therefore, after time t1, the first switching transistor S is turned on with zero voltage. C1During the t1-t2 phase, the AC power supply begins to supply power to the secondary side through the primary winding of the high-frequency transformer, while the freewheeling current in the active clamping circuit gradually becomes zero; the time t for this to become zero is:

[0018]

[0019] Among them, i LF For the AC side inductor current, L f NE is the AC side filter inductor, and NE is the voltage of the clamping capacitor when it is fully charged.

[0020] At this time, the active clamping circuit is operating in clamping mode, and the clamping capacitor C... CL Through the first switching transistor S C1 and the fourth switch S C4 To achieve voltage clamping, the input voltage v on the primary side of the high-frequency transformer is... CD Clamped to NE, the primary current i of the high-frequency transformer during the t1-t2 stage C for:

[0021]

[0022] Among them, i C L is the primary current of the high-frequency transformer. f NE is the AC side filter inductor, and NE is the voltage of the clamping capacitor when it is fully charged.

[0023] S4, during the t2-t3 phase, at time t2, the first switch S1 is turned off in zero-voltage mode.

[0024] Furthermore, it also includes the following steps:

[0025] S5, in the t3-t4 stage, where the sawtooth wave carrier u cw The falling edge occurs at time t4. At the start of the t3-t4 phase, the second MOSFET S2 is fully voltage-on at time t3, and the secondary voltage of the high-frequency transformer is v. AB It becomes 0 at time t3; the secondary current i of the high-frequency transformer A Continuous energy transfer is achieved through the freewheeling path formed by the parasitic diode D4 of the second MOSFET S2 and the fourth MOSFET S4; the second switch S C2 parasitic diode D C2 During the natural conduction phase (t3-t4), the active clamping circuit operates in freewheeling mode. The active clamping circuit is activated by the fourth switch S. C4 Second switch S C2 parasitic diode D C2 Complete the freewheeling current of the filter inductor; after the second MOSFET S2 is turned on, the second switch S... C2 It is turned on in zero-voltage mode, where v CD=0.

[0026] S6, during the t4-t5 phase, where t4 plus a certain overlap circulation time equals t5, at t4, the sixth master MOSFET S6, the sixth slave MOSFET S'6, the seventh master MOSFET S7, and the seventh slave MOSFET S'7 are turned on, and the active clamping circuit is activated through the fourth switch S... C4 Second switch S C2 parasitic diode D C2 To continue streaming.

[0027] Furthermore, it also includes the following steps:

[0028] S7, during the t5-t6 phase, the modulated wave -u mw With the sawtooth wave carrier u of the next cycle cw The intersection of the rising edges is defined as time t6. At time t5, due to the active clamping circuit, the voltage v across the fifth master MOSFET S5 and the fifth slave MOSFET S'5... CE The voltage v across the eighth master MOSFET S8 and the eighth slave MOSFET S'8 DF All are zero. At this time, the fifth master MOSFET S5 and the fifth slave MOSFET S5', the eighth master MOSFET S8 and the eighth slave MOSFET S'8 are turned off with zero voltage. The primary current of the high-frequency transformer flows through the fourth switch S of the active clamping circuit. C4 Second switch S C2 parasitic diode D C2 The conduction enables freewheeling. Due to the natural conduction of the parasitic diode D4 of the fourth MOSFET S4, the fourth MOSFET S4 is turned off at zero voltage at time t6.

[0029] S8, single-phase high-frequency rectifier at t6-t 12 The state of this stage is similar to that of the t0-t6 stage, where the secondary current i of the high-frequency transformer... A In t6-t 12 The polarity reversal from positive to negative is completed within the time period; the single-phase high-frequency rectifier completes the reversal from positive to negative within the time period t0-t. 12 For a complete work cycle, in t 12 Each cycle completes at a time, entering the next cycle mode, forming a periodic cyclical working mode; when the modulated wave u mw When the value is positive, each MOSFET completes its corresponding operation according to the predetermined timing sequence; when u mwWhen the value is negative, the leading and lagging bridge arms are swapped, the third MOSFET S3 and the fourth MOSFET S4 become the leading bridge arms, and the first MOSFET S1 and the second MOSFET S2 become the lagging bridge arms. The switching logic of each MOSFET is similar to that of the positive half-cycle operation.

[0030] The present invention has the following beneficial effects:

[0031] This invention effectively eliminates voltage spikes and ensures safe current commutation through the synergistic effect of active clamping circuit and improved modulation strategy. It also achieves soft switching of most switching transistors, effectively improving the service life of each switching transistor in the system, significantly enhancing the efficiency of the inverter system, and ensuring better system safety and reliability. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0033] Figure 1 A diagram of a single-phase high-frequency rectifier with clamping circuit according to the present invention is shown.

[0034] Figure 2 The modulation strategy diagram of a single-phase high-frequency rectifier without active clamping circuitry is shown.

[0035] Figure 3 A modulation strategy diagram of a single-phase high-frequency rectifier with active clamping circuitry is shown.

[0036] Figure 4 Mode 1, before t0 is shown. Figure 1 The circuit continuity diagram.

[0037] Figure 5 Mode 2 is shown, t0-t1 Figure 1 The circuit continuity diagram.

[0038] Figure 6 Mode 3 is shown, t1-t2 Figure 1 The circuit continuity diagram.

[0039] Figure 7 Mode 4, t2-t3 is shown. Figure 1 The circuit continuity diagram.

[0040] Figure 8 Mode 5, t3-t4 is shown. Figure 1 The circuit continuity diagram.

[0041] Figure 9 Mode 6, t4-t5 is shown. Figure 1 The circuit continuity diagram.

[0042] Figure 10 Mode 7, t5-t7, is shown. Figure 1 The circuit continuity diagram.

[0043] Figure 11 The waveforms of AC winding voltage and load voltage without the introduction of an active clamping circuit are shown.

[0044] Figure 12 The waveforms of AC winding voltage and load voltage are shown when an active clamping circuit is introduced.

[0045] Figure 13 The DC-side output voltage and v of a single-phase high-frequency rectifier in steady state are shown. R and AC side inductor current i Lf Waveform diagram.

[0046] Figure 14 This shows the AC current measurement of a single-phase high-frequency rectifier. Lf THD analysis chart.

[0047] Figure 15 The drive signal v is shown when the third MOSFET S3 is turned on. GS Its drain-source voltage v DS The experimental waveform diagram.

[0048] Figure 16 The drive signal v is shown when the third MOSFET S3 is turned off. GS Its drain-source voltage v DS The experimental waveform diagram.

[0049] Figure 17 The drive signal v is shown when the first MOSFET S1 is turned on. GS Its drain-source voltage v DS The experimental waveform diagram.

[0050] Figure 18 The drive signal v is shown when the first MOSFET S1 is turned off. GS Its drain-source voltage v DS The experimental waveform diagram.

[0051] Figure 19 The drive signal v is shown when the first MOSFET Sc1 is turned on. GS Its drain-source voltage v DS The experimental waveform diagram.

[0052] Figure 20 The drive signal v is shown when the first switch Sc1 is turned off. GS Its drain-source voltage v DS The experimental waveform diagram.

[0053] Figure 21 The driving signal v is shown when the second switch Sc2 is turned on. GS Its drain-source voltage v DS The experimental waveform diagram.

[0054] Figure 22 The drive signal v is shown when the second switch Sc2 is turned off. GS Its drain-source voltage v DS The experimental waveform diagram.

[0055] Figure 23 The drive signal v is shown when the third switch Sc3 is turned on. GS Its drain-source voltage v DS The experimental waveform diagram.

[0056] Figure 24 The drive signal v is shown when the third switch Sc3 is turned off. GS Its drain-source voltage v DS The experimental waveform diagram.

[0057] Figure 25 The drive signal v is shown when the fourth switch Sc4 is turned on. GS Its drain-source voltage v DS The experimental waveform diagram.

[0058] Figure 26 The drive signal v is shown when the fourth switch Sc4 is turned off. GS Its drain-source voltage v DS The experimental waveform diagram.

[0059] Figure 27 The drive signal v of the fifth MOSFET S5 is shown. GS With the voltage v across the bidirectional switching transistor CE The experimental waveform diagram.

[0060] Figure 28 The drive signal v of the seventh MOSFET S7 is shown. GS With the voltage v across the bidirectional switching transistor CF The experimental waveform diagram. Detailed Implementation

[0061] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] like Figure 1 The single-phase high-frequency rectifier with clamping circuit shown includes: a matrix converter, an active clamping circuit, and a full-bridge rectifier; the matrix converter includes two bridge arms, each bridge arm including: two pairs of bidirectional power switches, each pair of bidirectional power switches consisting of two N-type anti-series power MOSFETs with a common source; the matrix converter is used to convert power frequency AC signals into high-frequency AC signals; the active clamping circuit is a full-bridge circuit, including: four MOSFETs and clamping capacitors, the active clamping circuit is used to eliminate the resonant voltage overshoot of the leakage inductance of the high-frequency transformer and the parasitic capacitance of the switching transistors, and cooperates with the matrix converter to complete the safe commutation of the inductor current; the active clamping circuit is connected in parallel with the output of the matrix converter; the full-bridge rectifier includes: four MOSFETs, the input terminal of the full-bridge rectifier is connected to the preceding matrix converter and active clamping circuit through a high-frequency transformer, and the output terminal of the full-bridge rectifier is connected in parallel with a filter capacitor and a resistor; the full-bridge rectifier is used to convert high-frequency AC signals into DC signals. The full-bridge rectifier, filter circuit, and resistive load are arranged on the secondary side of the high-frequency isolation transformer; the matrix converter and active clamping circuit are arranged on the primary side of the high-frequency transformer.

[0063] Specifically, the matrix converter has two identical bridge arms, the fifth and sixth. In the fifth bridge arm, the sources of the fifth master MOSFET S5 and the fifth slave MOSFET S5' are connected, as are the sources of the sixth master MOSFET S6 and the sixth slave MOSFET S6'. The drains of the fifth slave MOSFET S5' and the sixth master MOSFET S6 are also connected. The matrix converter consists of eight MOSFETs: S5, S5', S6, S6', S7, S7', S8, and S8'.

[0064] Specifically, the matrix converter also includes: AC power supply V AC and grid-side filter inductor L f The positive terminal of the AC power supply is connected to the mains-side filter inductor L. f Then, it is connected to the drain of the fifth slave MOSFET S5' and the drain of the sixth master MOSFET S6; the negative terminal of the AC power supply is connected to the drain of the seventh slave MOSFET S7' and the drain of the eighth master MOSFET S8 of the sixth bridge arm.

[0065] Specifically, the active clamping circuit includes two bridge arms, a third bridge arm and a fourth bridge arm. The third bridge arm and the fourth bridge arm are identical. The third switch S of the fourth bridge arm... C3 The source and the fourth switch S C4 The drains of the seventh main MOSFET S7 of the sixth bridge arm, the drain of the fifth main MOSFET S5, and the first switch S7 of the third bridge arm are connected; C1 The drains of the sixth bridge arm are connected to the drains of the eighth slave MOSFET S8', the drain of the sixth slave MOSFET S6', and the eighth switch S. C4 The drains are connected; the active clamping circuit also includes a clamping capacitor C. CL Clamping capacitor C CL One end is connected to the first switching transistor S C1 The drain of the third switch S in the fourth bridge arm C3 The drain, clamping capacitor C CL The other end is connected to the second switch S of the third bridge arm. C2 The drain and the fourth switch S C4 The drain of the active clamp circuit consists of four switching transistors S. c1 -S c4 and clamping capacitor C CL composition.

[0066] Specifically, the full-bridge rectifier includes: a high-frequency transformer, a first bridge arm, and a second bridge arm. The first and second bridge arms are identical, and also identical to the third and fourth bridge arms. One end of the primary side of the high-frequency transformer is connected to the drain of the seventh main MOSFET S7 and the drain of the fifth main MOSFET S5, and the other end is connected to the drain of the eighth slave MOSFET S8' and the drain of the sixth slave MOSFET S6'. One end of the secondary side of the high-frequency transformer is connected to the drain of the fourth MOSFET S4 of the second bridge arm and the source of the third MOSFET S3 of the second bridge arm, and the other end is connected to the source of the first MOSFET S1 of the first bridge arm and the drain of the second MOSFET S2 of the first bridge arm. The full-bridge rectifier includes resistors R and filter capacitors C. d The first and second bridge arms are connected in parallel. The full-bridge rectifier consists of four MOSFETs S1-S4, which transform the originally uncontrollable diodes into controllable switches, facilitating the subsequent bidirectional power conversion.

[0067] Figure 2 This demonstrates the SPWPM unipolar phase-shift modulation strategy without clamping circuitry. Where u mw and -u mw Indicates the modulated signal, u cwThe carrier signal is represented by a sawtooth wave. The secondary-side full-bridge circuit operates in phase-shift modulation mode, where the width of the input pulse varies sinusoidally. In the modulation wave u... mw When the value is greater than 0, S1S2 is the leading arm and S3S4 is the lagging arm; in the modulated wave u mw When the value is less than 0, the leading arm and the lagging arm are interchanged.

[0068] This invention provides a modulation method for a single-phase high-frequency rectifier with clamping circuit, using a sawtooth wave as the carrier wave and a modulation wave u mw With carrier u cw The intersection of the rising edges marks the switching point of the first MOSFET S1. The drive signal of the second MOSFET S2 is complementary to the drive signal of the first MOSFET S1; modulation wave -u mw With carrier u cw The intersection of the rising edges is the switching point of the third MOSFET S3. The drive signal of the fourth MOSFET S4 is complementary to the drive signal of the third MOSFET S3. To prevent short circuits caused by the simultaneous conduction of two switches on the same arm of the secondary H-bridge converter, a dead time needs to be added between the PWM signals of S1 and S2, and S3 and S4. At the falling edge of the carrier, the upper half of each arm of the primary-side matrix converter and the lower half of the other arm conduct simultaneously, and the upper and lower half arms of the same arm conduct complementaryly. The duty cycle of each PWM drive signal of the matrix converter is always 0.5. To alleviate the harmful voltage spikes caused by the interruption of the current path at the moment of circuit disconnection, the commutation path of the leakage inductance current can be increased by overlapping the conduction of S5S'5S'8S8 and S6S'6S7S'7.

[0069] like Figure 3 As shown, in the modulated wave u mw When the voltage is greater than 0, the operation process of one switching cycle is as follows. Assume the single-phase high-frequency rectifier is already operating in a steady state, where the output voltage has stabilized at E, and the clamping capacitor C of the clamping circuit... CL The fully charged circuit is NE, where N = N2 / N1, representing the turns ratio of the primary to secondary windings of the high-frequency transformer. The grid-side filter inductor L... f Much greater than the leakage inductance L of a high-frequency transformer K Furthermore, all switching transistors are of the same model, and their parasitic capacitance is C. R The reference voltage on the capacitor is specified to be positive at the top and negative at the bottom, and the leakage inductance L on the secondary side of the high-frequency transformer is specified. K The positive direction of the current is from left to right.

[0070] A modulation method for a single-phase high-frequency rectifier with clamping circuit, specifically including the following steps:

[0071] S1, Mode 1, (modulating wave -u)mw With sawtooth wave carrier u cw The intersection of the rising edges is defined as time t0. Before time t0, the matrix converter achieves a safe commutation process of the filter inductor current through an active clamping circuit, preventing sudden changes in the direction of the high-frequency transformer winding current and avoiding voltage spikes caused by sudden changes in current direction. Figure 4 As shown, at this time, on the primary side of the high-frequency transformer, the second switching transistor S in the active clamping circuit... C2 and the fourth switch S C4 parasitic diode D C4 When in the conducting state, it represents the reverse current i on the primary side of the high-frequency transformer. C Provide a freewheeling path to prevent sudden current changes; on the secondary side of the high-frequency transformer, the secondary current i of the high-frequency transformer... A Since the voltage is less than 0, the parasitic diode D3 of the first MOSFET S1 and the third MOSFET S3 remains on, so the secondary output voltage v of the high-frequency transformer is... AB =0;

[0072] In mode S2, during the t0-t1 phase, time t0 plus a certain dead time equals time t1. Before time t0, the parasitic diode D3 of the third MOSFET S3 is turned on, and at time t0, the third MOSFET S3 achieves zero-voltage turn-off. After the third MOSFET S3 turns off, the secondary circuit of the high-frequency transformer still forms a loop through the parasitic diode D3 of the first MOSFET S1 and the third MOSFET S3. Therefore, the secondary output voltage v of the high-frequency transformer... AB The value remains at 0; the second switch S C2 Before the fourth MOSFET S4 turns on, i.e., at time t1, zero-voltage turn-off is completed; the second switch S C2 After shutting down, as Figure 5 As shown, the clamping capacitor C during the t0-t1 stage CL It begins to charge, for i ′ C =i C +i LF , where i ′ C i is the clamping circuit current. C i is the primary current of the high-frequency transformer. LF AC side inductor current; clamping capacitor C CL The voltage across the two ends is Where t is the current time; at time t1, the primary input voltage v of the high-frequency transformer is... CD The voltage v on the secondary side of the high-frequency transformer is raised to NE. AB It was elevated to E.

[0073] Specifically, it also includes the following steps:

[0074] S3, mode 3, in the t1-t2 phase, such as Figure 6 As shown, time t2 is obtained by subtracting a certain dead time from time t3, and the modulated wave u mw With sawtooth wave carrier u cw The intersection of the rising edges is at time t3. At time t1, the fourth MOSFET S4 is turned on in zero-current mode (ZCS), and at the same time, the parasitic diode D4 of the fourth MOSFET S4 is naturally turned on, providing the conditions for the zero-voltage turn-off of the fourth switch S4 in the subsequent stage, driving the secondary current i of the high-frequency transformer. A Complete the positive transformation (i A >0). Due to the first switching transistor S during the t0-t1 stage. C1 parasitic diode D C1 Therefore, after time t1, the first switching transistor S is turned on with zero voltage. C1 During the t1-t2 phase, the AC power supply begins to supply power to the secondary side through the primary winding of the high-frequency transformer, while the freewheeling current in the active clamping circuit gradually becomes zero; the time t for this to become zero is:

[0075]

[0076] Among them, i LF For the AC side inductor current, L f NE is the AC side filter inductor, and NE is the voltage of the clamping capacitor when it is fully charged.

[0077] At this time, the active clamping circuit is operating in clamping mode, and the clamping capacitor C... CL Through the first switching transistor S C1 and the fourth switch S C4 To achieve voltage clamping, the input voltage v on the primary side of the high-frequency transformer is... CD Clamped to NE to prevent voltage oscillations on the primary side of the high-frequency transformer. Before time t2, the switching transistor S... C1 To shut down, because of this stage S C1 The circuit is conducting and a capacitor is connected in parallel across its terminals, with a voltage of 0 across the capacitor. C1 Zero-voltage shutdown is possible. The primary current i of the high-frequency transformer during the t1-t2 stage. C for:

[0078]

[0079] Among them, i C L is the primary current of the high-frequency transformer. f NE is the AC side filter inductor, and NE is the voltage of the clamping capacitor when it is fully charged.

[0080] S4, mode 4, in the t2-t3 phase, such as Figure 7As shown, during this transition phase, since the first parasitic diode D1 naturally conducts in the previous phase, it creates the condition for the first switch S1 to turn off at zero voltage. At time t2, the first switch S1 turns off in zero voltage mode.

[0081] Specifically, it also includes the following steps:

[0082] S5, mode 5, in the t3-t4 stage, such as Figure 8 As shown, the sawtooth wave carrier u cw The falling edge occurs at time t4. At the start of the t3-t4 phase, the second MOSFET S2 is fully voltage-on at time t3, and the secondary voltage of the high-frequency transformer is v. AB It becomes 0 at time t3; the secondary current i of the high-frequency transformer A Continuous energy transfer is achieved through the freewheeling path formed by the parasitic diode D4 of the second MOSFET S2 and the fourth MOSFET S4; the second switch S C2 parasitic diode D C2 Natural conduction, for the second switching transistor S C2 This creates the conditions for zero-voltage turn-on. During the t3-t4 phase, the active clamp circuit operates in freewheeling mode. The active clamp circuit, through the fourth switch S... C4 Second switch S C2 parasitic diode D C2 Complete the freewheeling current of the filter inductor; after the second MOSFET S2 is turned on, the second switch S... C2 It is turned on in zero-voltage mode, where v CD =0;

[0083] S6, mode 6, occurs during the t4-t5 phase, where t4 is time t5 by adding a certain amount of overlapping circulation time. Figure 9 As shown, this stage is the critical commutation stage. At time t4, the sixth master MOSFET S6, the sixth slave MOSFET S'6, the seventh master MOSFET S7, and the seventh slave MOSFET S'7 are turned on. That is, the primary circuit of the high-frequency transformer is simultaneously commutated by two branches, S6S'6S7S'7 and S5S'5S8S'8. At the same time, the active clamping circuit is also operating in freewheeling mode. The active clamping circuit is connected to the fourth switch S... C4 Second switch S C2 parasitic diode D C2 This allows for freewheeling, providing more commutation paths for the filter inductor current. Due to the active clamping circuit, v... CF =v DE =0, S6S'6S7S'7 is turned on in zero-voltage mode.

[0084] Specifically, it also includes the following steps:

[0085] S7, mode 7, in the t5-t6 stage, such as Figure 10 As shown, the modulated wave -u mw With the sawtooth wave carrier u of the next cycle cw The intersection of the rising edges is defined as time t6. At time t5, due to the active clamping circuit, the voltage v across the fifth master MOSFET S5 and the fifth slave MOSFET S'5... CE The voltage v across the eighth master MOSFET S8 and the eighth slave MOSFET S'8 DF All are zero. At this time, the fifth master MOSFET S5 and the fifth slave MOSFET S5', the eighth master MOSFET S8 and the eighth slave MOSFET S'8 are turned off with zero voltage. The primary current of the high-frequency transformer flows through the fourth switch S of the active clamping circuit. C4 Second switch S C2 parasitic diode D C2 The conduction enables freewheeling, preventing instantaneous current changes in the high-frequency transformer windings and eliminating voltage overshoot and oscillation in the single-phase high-frequency rectifier at this moment. Due to the natural conduction of the parasitic diode D4 of the fourth MOSFET S4, the fourth MOSFET S4 is turned off at zero voltage at time t6.

[0086] S8, single-phase high-frequency rectifier at t6-t 12 The state of this stage is the same as that of the t0-t6 stage, where the secondary current i of the high-frequency transformer... A In t6-t 12 The polarity reversal from positive to negative is completed within the phase; the single-phase high-frequency rectifier completes the t0-t phase. 12 For a complete work cycle, in t 12 Each cycle completes at a time, entering the next cycle mode, forming a periodic cyclical working mode; when the modulated wave u mw When the value is positive, each MOSFET completes its corresponding operation according to the predetermined timing sequence; when u mw When the value is negative, the leading and lagging bridge arms are swapped. The third MOSFET S3 and the fourth MOSFET S4 become the leading bridge arms, while the first MOSFET S1 and the second MOSFET S2 become the lagging bridge arms. The switching logic of each MOSFET is similar to that in the positive half-cycle operation. In addition, all power switching devices achieve efficient operation with full or partial soft switching, effectively reducing switching losses.

[0087] Figure 11 and Figure 12 The following parameters are provided: the AC winding voltage V of the high-frequency transformer before and after the introduction of the active clamping circuit in a single-phase high-frequency rectifier. CD and DC-side resistive load voltage v R The waveform. By comparison Figure 11 and Figure 12 It can be observed that the active clamping circuit can effectively eliminate voltage spikes, significantly reduce waveform distortion, and thus greatly improve the power quality of the entire system.

[0088] Figure 13 This demonstrates the DC-side output voltage v when a single-phase high-frequency rectifier is connected to a 13Ω resistive load. R and AC side inductor current i Lf The steady-state response. The single-phase high-frequency rectifier produces a stable 60V load voltage output, and the grid-side voltage v AC and AC side inductor current i Lf No obvious distortion or phase difference was observed, and the input power factor angle was 0°. Figure 14 It is a single-phase high-frequency rectifier AC current measurement i Lf The THD analysis showed that the AC side current i Lf The total harmonic distortion (THD) is 3.59%.

[0089] like Figure 15 , 16 As shown in 17 and 18, in i Lf When the voltage is ≥0, the switch S3 can turn on and off under zero voltage conditions, but the switch S1 can only turn off under zero voltage conditions. The turn-on of the switch is achieved under full voltage stress conditions.

[0090] Figures 19-26 S was provided respectively C1 ~S C4 The switching waveform, such as Figures 19-26 As shown, S C1 ~S C4 All four switching transistors can achieve zero-voltage turn-on and zero-voltage turn-off, and their drain-source voltage v DS No obvious voltage spikes were observed.

[0091] Figure 27 and Figure 28 The waveforms of the switching transistors S5S'5 and S7S'7 are provided. It can be seen that the bidirectional switching transistor S5S'5 is at v CE =0 during the period of conduction and cutoff under zero voltage condition, S7S'7 at v CF During the period = 0, the transistors are turned on and off under zero-voltage conditions. Since S5S'5S8S'8 and S6S'6S7S'7 have the same turn-on sequence, the bidirectional switches S6S'6 and S8S'8 are also turned on and off under zero-voltage conditions.

[0092] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A single-phase high-frequency rectifier with clamping circuit, characterized in that, include: Matrix converter, active clamping circuit and full-bridge rectifier; The matrix converter includes two bridge arms, each including two pairs of bidirectional power switches, each pair consisting of two N-type anti-series power MOSFETs with a common source. The matrix converter converts power frequency AC signals to high-frequency AC signals. The active clamping circuit is a full-bridge circuit, including four MOSFETs and clamping capacitors. The active clamping circuit eliminates the resonant voltage overshoot caused by the leakage inductance of the high-frequency transformer and the parasitic capacitance of the switching transistors, and works with the matrix converter to safely commutate the inductor current. The active clamping circuit is connected in parallel with the output of the matrix converter. The full-bridge rectifier includes four MOSFETs. The input of the full-bridge rectifier is connected to the preceding matrix converter and active clamping circuit via a high-frequency transformer. The output of the full-bridge rectifier is connected in parallel with a filter capacitor and a resistor. The full-bridge rectifier converts high-frequency AC signals to DC signals.

2. A single-phase high-frequency rectifier with clamping circuit according to claim 1, characterized in that, The matrix converter has two bridge arms, the fifth bridge arm and the sixth bridge arm. The two bridge arms are identical. The sources of the fifth master MOSFET S5 and the fifth slave MOSFET S5' in the fifth bridge arm are connected. The sources of the sixth master MOSFET S6 and the sixth slave MOSFET S6' in the fifth bridge arm are connected. The drain of the fifth slave MOSFET S5' in the fifth bridge arm is connected to the drain of the sixth master MOSFET S6 in the fifth bridge arm.

3. A single-phase high-frequency rectifier with clamping circuit according to claim 2, characterized in that, The matrix converter also includes: AC power supply V AC and grid-side filter inductor L f The positive terminal of the AC power supply is connected to the mains-side filter inductor L. f Then, it is connected to the drain of the fifth slave MOSFET S5' and the drain of the sixth master MOSFET S6; the negative terminal of the AC power supply is connected to the drain of the seventh slave MOSFET S7' and the drain of the eighth master MOSFET S8 of the sixth bridge arm.

4. A single-phase high-frequency rectifier with clamping circuit according to claim 1, characterized in that, The active clamping circuit includes two bridge arms, a third bridge arm and a fourth bridge arm. The third bridge arm and the fourth bridge arm are identical. The third switch S of the fourth bridge arm... C3 The source and the fourth switch S C4 The drains of the seventh main MOSFET S7 of the sixth bridge arm, the drain of the fifth main MOSFET S5, and the first switch S7 of the third bridge arm are connected; C1 The drains of the sixth bridge arm are connected to the drains of the eighth slave MOSFET S8', the drain of the sixth slave MOSFET S6', and the eighth switch S. C4 The drains are connected; the active clamping circuit also includes a clamping capacitor C. CL Clamping capacitor C CL One end is connected to the first switching transistor S C1 The drain of the third switch S in the fourth bridge arm C3 The drain, clamping capacitor C CL The other end is connected to the second switch S of the third bridge arm. C2 The drain and the fourth switch S C4 The drain electrode.

5. A single-phase high-frequency rectifier with clamping circuit according to claim 1, characterized in that, The full-bridge rectifier includes: a high-frequency transformer, a first bridge arm, and a second bridge arm. The first and second bridge arms are identical, and also identical to the third and fourth bridge arms. One end of the primary winding of the high-frequency transformer is connected to the drain of the seventh main MOSFET S7 and the drain of the fifth main MOSFET S5, and the other end is connected to the drain of the eighth slave MOSFET S8' and the drain of the sixth slave MOSFET S6'. One end of the secondary winding of the high-frequency transformer is connected to the drain of the fourth MOSFET S4 of the second bridge arm and the source of the third MOSFET S3 of the second bridge arm, and the other end is connected to the source of the first MOSFET S1 of the first bridge arm and the drain of the second MOSFET S2 of the first bridge arm. The full-bridge rectifier includes resistors R and filter capacitors C. d The first and second bridge arms are connected in parallel.

6. A modulation method for a single-phase high-frequency rectifier with clamping circuit, utilizing the single-phase high-frequency rectifier according to any one of claims 1-5, characterized in that, Using a sawtooth wave as the carrier wave, the modulated wave u mw With carrier u cw The intersection of the rising edges marks the switching point of the first MOSFET S1. The drive signal of the second MOSFET S2 is complementary to the drive signal of the first MOSFET S1; modulation wave -u mw With carrier u cw The intersection of the rising edges is the switching point of the third MOSFET S3. The drive signal of the fourth MOSFET S4 is complementary to the drive signal of the third MOSFET S3. A dead time is added between the PWM signals of the first MOSFET S1 and the second MOSFET S2, the third MOSFET S3 and the fourth MOSFET S4.

7. The modulation method for a single-phase high-frequency rectifier with clamping circuit according to claim 6, characterized in that, Specifically, the steps include the following: S1 will modulate the wave -u mw With sawtooth wave carrier u cw The intersection of the rising edges is defined as time t0. Before time t0, in the active clamping circuit on the primary side of the high-frequency transformer, the second switching transistor S... C2 and the fourth switch S C4 parasitic diode D C4 When in the conducting state, it represents the reverse current i on the primary side of the high-frequency transformer. C Provide a continuation path; On the secondary side of the high-frequency transformer, the secondary current i of the high-frequency transformer... A When the voltage is less than 0, the parasitic diode D3 of the first MOSFET S1 and the third MOSFET S3 remains in the conducting state, and the secondary output voltage of the high-frequency transformer is v. AB =0; In phase S2, t0-t1, time t0 plus a certain dead time equals time t1. Before time t0, the parasitic diode D3 of the third MOSFET S3 is turned on, and at time t0, the third MOSFET S3 achieves zero-voltage turn-off. After the third MOSFET S3 turns off, the secondary circuit of the high-frequency transformer still forms a loop through the parasitic diode D3 of the first MOSFET S1 and the third MOSFET S3. The secondary output voltage v of the high-frequency transformer... AB The value remains at 0; the second switch S C2 Before the fourth MOSFET S4 turns on, i.e., at time t1, zero-voltage turn-off is completed; the second switch S C2 After being turned off, the clamping capacitor C is used during the t0-t1 phase. CL The circuit begins charging, and the clamping circuit current is i. ′ C =i C +i LF , where i ′ C i is the clamping circuit current. C i is the primary current of the high-frequency transformer. LF AC side inductor current; clamping capacitor C CL The voltage across the two ends is Where t is the current time; at time t1, the primary input voltage v of the high-frequency transformer is... CD The voltage v on the secondary side of the high-frequency transformer is raised to NE. AB It was elevated to E.

8. The modulation method for a single-phase high-frequency rectifier with clamping circuit according to claim 7, characterized in that, It also includes the following steps: S3, during the t1-t2 phase, time t3 minus a certain dead time equals time t2, the modulated wave u mw With sawtooth wave carrier u cw The intersection of the rising edges is at time t3. At time t1, the fourth MOSFET S4 is turned on in zero-current mode, and at the same time, the parasitic diode D4 of the fourth MOSFET S4 is naturally turned on. Since the first switching transistor S4 is in the t0-t1 stage... C1 parasitic diode D C1 Therefore, after time t1, the first switching transistor S is turned on with zero voltage. C1 During the t1-t2 phase, the AC power supply begins to supply power to the secondary side through the primary winding of the high-frequency transformer, while the freewheeling current in the active clamping circuit gradually becomes zero; the time t for this to become zero is: Among them, i LF For the AC side inductor current, L f NE is the AC side filter inductor, and NE is the voltage of the clamping capacitor when it is fully charged. At this time, the active clamping circuit is operating in clamping mode, and the clamping capacitor C... CL Through the first switching transistor S C1 and the fourth switch S C4 To achieve voltage clamping, the input voltage v on the primary side of the high-frequency transformer is... CD Clamped to NE, the primary current i of the high-frequency transformer during the t1-t2 stage C for: Among them, i C L is the primary current of the high-frequency transformer. f NE is the AC side filter inductor, and NE is the voltage of the clamping capacitor when it is fully charged. S4, during the t2-t3 phase, at time t2, the first switch S1 is turned off in zero-voltage mode.

9. The modulation method for a single-phase high-frequency rectifier with clamping circuit according to claim 8, characterized in that, It also includes the following steps: S5, in the t3-t4 stage, where the sawtooth wave carrier u cw The falling edge occurs at time t4. At the start of the t3-t4 phase, the second MOSFET S2 is fully voltage-on at time t3, and the secondary voltage of the high-frequency transformer is v. AB It becomes 0 at time t3; the secondary current i of the high-frequency transformer A Continuous energy transfer is achieved through the freewheeling path formed by the parasitic diode D4 of the second MOSFET S2 and the fourth MOSFET S4; the second switch S C2 parasitic diode D C2 During the natural conduction phase (t3-t4), the active clamping circuit operates in freewheeling mode. The active clamping circuit is activated by the fourth switch S. C4 Second switch S C2 parasitic diode D C2 Complete the freewheeling current of the filter inductor; after the second MOSFET S2 is turned on, the second switch S... C2 It is turned on in zero-voltage mode, where v CD =0; S6, during the t4-t5 phase, where t4 plus a certain overlap circulation time equals t5, at t4, the sixth master MOSFET S6, the sixth slave MOSFET S'6, the seventh master MOSFET S7, and the seventh slave MOSFET S'7 are turned on, and the active clamping circuit is activated through the fourth switch S... C4 Second switch S C2 parasitic diode D C2 To continue streaming.

10. The modulation method for a single-phase high-frequency rectifier with clamping circuit according to claim 9, characterized in that, It also includes the following steps: S7, during the t5-t6 phase, the modulated wave -u mw With the sawtooth wave carrier u of the next cycle cw The intersection of the rising edges is defined as time t6. At time t5, due to the active clamping circuit, the voltage v across the fifth master MOSFET S5 and the fifth slave MOSFET S'5... CE The voltage v across the eighth master MOSFET S8 and the eighth slave MOSFET S'8 DF All are zero. At this time, the fifth master MOSFET S5 and the fifth slave MOSFET S5', the eighth master MOSFET S8 and the eighth slave MOSFET S'8 are turned off with zero voltage. The primary current of the high-frequency transformer flows through the fourth switch S of the active clamping circuit. C4 Second switch S C2 parasitic diode D C2 The conduction enables freewheeling. Due to the natural conduction of the parasitic diode D4 of the fourth MOSFET S4, the fourth MOSFET S4 is turned off at zero voltage at time t6. S8, single-phase high-frequency rectifier at t6-t 12 The state of this stage is similar to that of the t0-t6 stage, where the secondary current i of the high-frequency transformer... A In t6-t 12 The polarity reversal from positive to negative is completed within the time period; the single-phase high-frequency rectifier completes the reversal from positive to negative within the time period t0-t. 12 For a complete work cycle, in t 12 Each cycle completes at a time, entering the next cycle mode, forming a periodic cyclical working mode; when the modulated wave u mw When the value is positive, each MOSFET completes its corresponding operation according to the predetermined timing sequence; when u mw When the value is negative, the leading and lagging bridge arms are swapped, the third MOSFET S3 and the fourth MOSFET S4 become the leading bridge arms, and the first MOSFET S1 and the second MOSFET S2 become the lagging bridge arms. The switching logic of each MOSFET is similar to that of the positive half-cycle operation.

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