Single-phase four-level rectifier power supply based on pseudo totem-pole structure

Abstract

Single-phase four-level rectifier power supply based on pseudo totem-pole structure, including 8 fully controlled power switch tube S1~S8, diode D1~D6, inductor L1, L2, capacitor C1~C3. AC power supply u g One end is connected with the anode of diode D5 and the cathode of diode D6 to the end point n; AC power supply u g The other end is connected with the one end of inductor L1 and the one end of inductor L2 respectively; the other end of inductor L1 is connected with the anode of diode D1 and the drain of switch tube S1 to the end point a respectively; the other end of inductor L2 is connected with the cathode of diode D2 and the source of switch tube S4 to the end point b respectively. The cathode of diode D1 is connected with the drain of switch tube S3, the cathode of diode D5, the positive electrode of capacitor C1 and the negative electrode of load R L The positive electrode is connected with the end point p; the source of switch tube S2 is connected with the anode of diode D2, the anode of diode D6, the negative electrode of capacitor C3 and the positive electrode of load R L The negative electrode is connected with the end point m. The rectifier of the application combines pseudo totem-pole rectification technology and four-level topology technology, which can effectively reduce the stress of switch tube, improve the overall efficiency of the system, and there is no bridge arm through phenomenon.

Description

TECHNICAL FIELD

[0001] The present application relates to a power conversion, single-phase active four-level rectifier topology, in particular to a single-phase four-level rectifier power supply based on a pseudo-totem pole structure. BACKGROUND

[0002] Traditional two-level rectifiers have been applied for decades, but their switching frequency is limited, and usually requires large inductance and large capacitance, making the overall size of the filter large and the efficiency low, and they have been replaced by emerging multi-level converters. Under the same conditions, the use of multi-level circuit design power factor correction circuit relative to two-level circuit can reduce the voltage stress of the switching tube, reduce electromagnetic interference, and its dynamic response is fast and efficient.

[0003] Four-level technology is a common way to solve the high voltage stress of switching tubes. When the rectifier is running, each switching device bears one-third of the bus voltage. And under the same DC side voltage conditions, the voltage variation of the power switching tube in the four-level structure rectifier is smaller, and the system fluctuation is more stable. Therefore, the use of four-level structure helps to make the rectifier more resistant to high voltage and reduce the cost. SUMMARY

[0004] The present application proposes a single-phase four-level rectifier power supply based on a pseudo-totem pole structure, which retains the advantage of no bridge arm shoot-through of the pseudo-totem pole; under the same power level, compared with the traditional two-level rectifier, it has the advantages of low harmonic content, small filter inductance volume, low power device voltage stress, and can reduce the cost of device selection.

[0005] The technical scheme adopted by the present application is:

[0006] The single-phase four-level rectifier power supply based on the pseudo-totem pole structure comprises: eight fully controlled power switching tubes S1-S8, six diodes D1-D6, inductors L1 and L2, and capacitors C1-C3.

[0007] The AC power supply u g One end is respectively connected to the anode of diode D5 and the cathode of diode D6, and the connection node constitutes the end point n.

[0008] The AC power supply u g The other end is respectively connected to one end of inductor L1 and one end of inductor L2, and the connection node constitutes the end point n.

[0009] The other end of inductor L1 is respectively connected to the anode of diode D1 and the drain of switching tube S1, and the connection node constitutes the end point a.

[0010] The other end of inductor L2 is respectively connected to the cathode of diode D2 and the source of switching tube S4, and the connection node constitutes the end point b.

[0011] The source of the switch tube S1 is connected to the drain of the switch tube S2 and the anode of the diode D4 respectively;

[0012] The source of the switch tube S3 is connected to the drain of the switch tube S4 and the cathode of the diode D3 respectively;

[0013] The anode of diode D3 is connected to the cathode of diode D4, the drain of switch S5, and the source of switch S7 respectively;

[0014] The source of the switch tube S5 is connected to the source of the switch tube S6; the drain of the switch tube S7 is connected to the drain of the switch tube S8;

[0015] The drain of the switch tube S6 is connected to the negative electrode of the capacitor C1 and the positive electrode of the capacitor C2 respectively, and the connection node constitutes the end point e;

[0016] The source of the switch tube S8 is connected to the negative electrode of the capacitor C2 and the positive electrode of the capacitor C3 respectively, and the connection node constitutes the terminal f;

[0017] The cathode of diode D1 is connected to the drain of switch tube S3, the cathode of diode D5, the positive electrode of capacitor C1, and the load R L The positive electrode, whose connection node constitutes the terminal point p;

[0018] The source of the switch tube S2 is connected to the anode of the diode D2, the anode of the diode D6, the negative electrode of the capacitor C3, and the load R L The negative electrode, the connection node of which constitutes the terminal m.

[0019] The diodes D1 and D2, the switches S1 to S4, and the inductors L1 and L2 form a pseudo totem pole structure.

[0020] The capacitors C1, C2, and C3 are series split capacitors, and the DC bus is composed of C1, C2, and C3. The capacitors C1, C2, and C3 are of the same model. Each capacitor withstands the DC bus voltage U dc One third of the four-level ±1 / 3U dc level.

[0021] The power switch tubes S1 to S8 are all insulated gate bipolar transistors IGBTs or integrated gate commutated thyristors IGCTs or power field effect transistors MOSFETs.

[0022] The converter has the following eight operating modes in CCM mode:

[0023] (1) Four working modes of positive half cycle:

[0024] Mode 1: All switches S1 to S8 are turned off, and the grid current i gThrough the inductor L1, a path is formed through the diode D1, capacitors C1, C2, C3, and diode D6. The power supply and inductor L1 together charge the capacitors C1, C2, and C3, and the charging current is equal to i g -i dc and to the load R L Power supply, load current equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =+U dc , voltage u between endpoint b and endpoint N bN =u g .

[0025] Mode 2: Switches S1 and S5 are turned on, and the grid current i g A path is formed through the inductor L1, the switch tube S1, the diode D4, the switch tube S5, the body diode on the switch tube S6, the capacitors C2, C3, and the diode D6. The power supply charges the capacitors C2 and C3, and the charging current is equal to i g -i dc , capacitor C1 discharges to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =+2U dc / 3, voltage u between endpoint b and endpoint N bN =u g .

[0026] Mode 3: Switches S1 and S8 are turned on, and the grid current i g A path is formed through the inductor L1, the switch S1, the diode D4, the body diode of the switch S7, the switch S8, the capacitor C3, and the diode D6. The power supply charges the capacitor C3, and the charging current is equal to i g -i dc , capacitors C1 and C2 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =+1U dc / 3, voltage u between endpoint b and endpoint N bN =u g .

[0027] Mode 4: Switches S1 and S2 are turned on, and the grid current i g Through the inductor L1, a path is formed through the switch tube S1, switch tube S2, and diode D6, and the AC power supply u g The inductor L1 is charged. The capacitors C1, C2, C3 and the load form another path. The capacitors C1, C2, C3 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN=0, voltage u between endpoint b and endpoint N bN =u g .

[0028] (2) Four working modes of negative half cycle:

[0029] Mode 5: Switches S3 and S4 are turned on, and the grid current i g A path is formed through diode D5, switch tube S3, switch tube S4, and inductor L2, and the AC power supply u g The inductor L1 is charged. The capacitors C1, C2, C3 and the load form another path. The capacitors C1, C2, C3 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =0.

[0030] Mode 6: Switches S4 and S6 are turned on, and the grid current i g A path is formed through diode D5, capacitor C1, switch S6, the body diode on switch S5, diode D3, switch S4, and inductor L2. The power supply charges capacitor C1, and the charging current is equal to -i g -i dc , capacitors C2 and C3 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-1U dc / 3.

[0031] Mode 7: Switches S4 and S7 are turned on, and the grid current i g A path is formed through diode D5, capacitors C1, C2, the body diode on switch S8, switch S7, diode D3, switch S4, and inductor L2. The power supply charges capacitors C1 and C2, and the charging current is equal to -i g -i dc , capacitor C3 discharges to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-2U dc / 3.

[0032] Mode 8: All switches S1 to S8 are turned off, and the grid current i gThrough diode D5, capacitors C1, C2, C3, diode D2, and inductor L2, a path is formed. The power supply and inductor L2 charge capacitors C1, C2, and C3, and the charging current is equal to -i g -i dc and to the load R L Power supply, load current equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-U dc .

[0033] The present invention provides a single-phase four-level rectifier power supply based on a pseudo-totem pole structure, and the technical effects are as follows:

[0034] 1. The converter of the present invention has boost and rectification functions. Three equal-value capacitors on the DC side are connected in series in the same direction to realize a four-level circuit. The voltage stress of the power device is low, and low-cost switching devices can be selected to save costs.

[0035] 2. The front end of the present invention adopts a pseudo-totem pole structure, which connects two identical inductors in parallel in the circuit to boost the voltage, reducing the nominal value and volume of the boost inductor and output capacitor. The overall design of the filter can be modularized in a small size, which is conducive to installation and application.

[0036] 3. Compared with the traditional two-level rectifier circuit, the use of a four-level rectifier circuit is beneficial to reducing the size of the filter inductor, reducing the harmonic content, achieving a higher power level, and can still achieve power output under fault conditions, thereby improving the reliability of the topology to a certain extent.

[0037] 4. The bridgeless structure reduces conduction loss and helps improve the overall efficiency of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below with reference to the accompanying drawings and examples:

[0039] Figure 1 This is a main topology diagram of a single-phase four-level rectifier power supply based on a pseudo totem pole structure according to the present invention.

[0040] Figure 2 This is a schematic diagram of the first working mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure of the present invention.

[0041] Figure 3 This is a schematic diagram of the second working mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure of the present invention.

[0042] Figure 4This is a schematic diagram of the third working mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure of the present invention.

[0043] Figure 5 This is a schematic diagram of the fourth operating mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure according to the present invention.

[0044] Figure 6 This is a schematic diagram of the fifth operating mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure according to the present invention.

[0045] Figure 7 This is a schematic diagram of the sixth operating mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure according to the present invention.

[0046] Figure 8 This is a schematic diagram of the seventh operating mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure according to the present invention.

[0047] Figure 9 This is a schematic diagram of the eighth operating mode of a single-phase four-level rectifier power supply based on a pseudo totem pole structure according to the present invention.

[0048] Figure 10 is the steady-state AC input voltage u of the present invention g And the steady-state AC input current i g Waveform graph.

[0049] Figure 11 The voltage u between point a and point N in the present invention aN Steady-state waveform diagram.

[0050] Figure 12 is the voltage u between point b and point N in the present invention bN Steady-state waveform diagram.

[0051] Figure 13 is the current i of the inductor L1 of the present invention L1 Waveform graph.

[0052] Figure 14 is the current i of the inductor L2 of the present invention L2 Waveform graph.

[0053] Figure 15 The voltage u of the DC split capacitors C1, C2, and C3 of the present invention is C1 、u C2 、u C3 Waveform graph.

[0054] Figure 16 is the steady-state output voltage U of the present invention dc Waveform graph. DETAILED DESCRIPTION

[0055] like Figure 1 The application is a single-phase four-level rectifier power supply based on a pseudo-totem-pole structure, which comprises:

[0056] 8 fully-controlled power switches S1, S2, S3, S4, S5, S6, S7, S8, 6 diodes D1, D2, D3, D4, D5, D6, inductors L1, L2, and capacitors C1, C2, C3;

[0057] AC power supply u g One end is connected to the anode of diode D5 and the cathode of diode D6 at terminal point n.

[0058] AC power supply u g The other end is respectively connected to one end of inductor L1 and one end of inductor L2.

[0059] The other end of inductor L1 is respectively connected to the anode of diode D1 and the drain of switch S1 at terminal point a.

[0060] The other end of inductor L2 is respectively connected to the cathode of diode D2 and the source of switch S4 at terminal point b.

[0061] The source of switch S1 is connected to the drain of switch S2 and the anode of diode D4.

[0062] The source of switch S3 is connected to the drain of switch S4 and the cathode of diode D3.

[0063] The anode of diode D3 is connected to the cathode of diode D4 and the drain of switch S5 and the source of switch S7.

[0064] The source of switch S5 is connected to the source of switch S6.

[0065] The drain of switch S7 is connected to the drain of switch S8.

[0066] The drain of switch S6 is connected to the negative electrode of capacitor C1 and the positive electrode of capacitor C2 at e.

[0067] The source of switch S8 is connected to the negative electrode of capacitor C2 and the positive electrode of capacitor C3 at f.

[0068] The cathode of diode D1 is connected to the drain of switch S3, the cathode of diode D5, the positive electrode of capacitor C1, and the positive electrode of load R L at terminal point p.

[0069] The anode of diode D2 is connected to the anode of diode D6, the negative electrode of capacitor C3, and the negative electrode of load R L at terminal point m.

[0070] The left diodes D1 and D2, switches S1-S4, and inductors L1 and L2 of the converter form a pseudo-totem-pole structure.

[0071] The capacitors C1, C2, and C3 are series split capacitors, and the DC bus is composed of C1, C2, and C3. The capacitors C1, C2, and C3 are of the same model. Each capacitor withstands the DC bus voltage U dc One third of the four-level ±1 / 3U dc level.

[0072] The power switch tubes S1 to S8 are all insulated gate bipolar transistors IGBTs or integrated gate commutated thyristors IGCTs or power field effect transistors MOSFETs.

[0073] The specific parameters of the circuit are as follows: The effective value of the AC power supply voltage is 220V, the frequency is 50Hz, and the DC side output voltage U dc =400V, inductor L1=L2=2mH, capacitor C1=C2=C3=4700μF, switching frequency fs=20kHz, load R L =50Ω.

[0074] The single-phase four-level rectifier power supply based on the pseudo totem pole structure has the following operating modes in CCM steady-state operation:

[0075] (1) Four working modes of positive half cycle:

[0076] Mode 1: If Figure 2 As shown, all the switches S1 to S8 are turned off, and the grid current i g Through the inductor L1, a path is formed through the diode D1, capacitors C1, C2, C3, and diode D6. The power supply and inductor L1 together charge the capacitors C1, C2, and C3, and the charging current is equal to i g -i dc and to the load R L Power supply, load current equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =+U dc , voltage u between endpoint b and endpoint N bN =u g .

[0077] Mode 2: If Figure 3 As shown, the switches S1 and S5 are turned on, and the grid current i g A path is formed through the inductor L1, the switch tube S1, the diode D4, the switch tube S5, the body diode on the switch tube S6, the capacitors C2, C3, and the diode D6. The power supply charges the capacitors C2 and C3, and the charging current is equal to i g -i dc , capacitor C1 discharges to the load, and the load current is equal to i dcIn this mode, the voltage u between terminal a and terminal n is aN =+2U dc / 3, voltage u between endpoint b and endpoint N bN =u g .

[0078] Mode 3: If Figure 4 As shown, the switches S1 and S8 are turned on, and the grid current i g A path is formed through the inductor L1, the switch S1, the diode D4, the body diode of the switch S7, the switch S8, the capacitor C3, and the diode D6. The power supply charges the capacitor C3, and the charging current is equal to i g -i dc , capacitors C1 and C2 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =+1U dc / 3, voltage u between endpoint b and endpoint N bN =u g .

[0079] Mode 4: If Figure 5 As shown, the switches S1 and S2 are turned on, and the grid current i g Through the inductor L1, a path is formed through the switch tube S1, switch tube S2, and diode D6, and the AC power supply u g The inductor L1 is charged. The capacitors C1, C2, C3 and the load form another path. The capacitors C1, C2, C3 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =0, voltage u between endpoint b and endpoint N bN =u g .

[0080] (2) Four working modes of negative half cycle:

[0081] Mode 5: If Figure 6 As shown, the switches S3 and S4 are turned on, and the grid current i g A path is formed through diode D5, switch tube S3, switch tube S4, and inductor L2, and the AC power supply u g The inductor L1 is charged. The capacitors C1, C2, C3 and the load form another path. The capacitors C1, C2, C3 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =0.

[0082] Mode 6: If Figure 7 As shown, the switches S4 and S6 are turned on, and the grid current i g A path is formed through diode D5, capacitor C1, switch S6, the body diode on switch S5, diode D3, switch S4, and inductor L2. The power supply charges capacitor C1, and the charging current is equal to -i g -i dc , capacitors C2 and C3 discharge to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-1U dc / 3.

[0083] Mode 7: If Figure 8 As shown, the switches S4 and S7 are turned on, and the grid current i g A path is formed through diode D5, capacitors C1, C2, the body diode on switch S8, switch S7, diode D3, switch S4, and inductor L2. The power supply charges capacitors C1 and C2, and the charging current is equal to -i g -i dc , capacitor C3 discharges to the load, and the load current is equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-2U dc / 3.

[0084] Mode 8: If Figure 9 As shown, all the switches S1 to S8 are turned off, and the grid current i g Through diode D5, capacitors C1, C2, C3, diode D2, and inductor L2, a path is formed. The power supply and inductor L2 charge capacitors C1, C2, and C3, and the charging current is equal to -i g -i dc and to the load R L Power supply, load current equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-U dc .

[0085] Based on the above analysis, eight modes are obtained from different combinations of switch states, and each mode corresponds to a voltage level, as shown in Table 1. In the table, "1" represents on and "0" represents off.

[0086] Table 1 Combinations of eight modal switch states

[0087]

[0088] Figure 10 To convert the alternating current i g The AC input current and AC side input voltage waveform after multiplying by 10 times the gain represent the AC input voltage u of the present invention. g and AC input current i g The waveform is well sinusoidal and the current i g Waveform and voltage u g The waveforms have the same frequency and phase, achieving the purpose of power factor correction.

[0089] Figure 11 、 Figure 12 is the steady-state output voltage U of the present invention aN 、U bN The waveform diagram shows that the topology of the present invention can achieve four-level rectification.

[0090] Figure 13 、 Figure 14 The current i of the two inductors L1 and L2 of the present invention are L1 、i L2 Waveform diagram. Current i L1 The waveform is 0 in the negative half cycle, that is, the inductor L1 does not work in the negative half cycle, and the inductor L2 current i L2 The waveform is 0 in the positive half cycle, and the g =i L1 +i L2 , i.e. i L1 、i L2 After the merger g Can achieve sinusoidal waveform.

[0091] Figure 15 The voltage U of the DC split capacitors C1, C2, and C3 of the present invention is C1 、U C2 、U C3 The waveform diagram shows that the voltage of a single series capacitor on the DC side of the present invention can be stabilized at around 133V.

[0092] Figure 16 is the steady-state output voltage U of the present invention dc Waveform, DC output voltage U dc It is stable at around 400V, proving the feasibility of the topology.

[0093] From the above analysis of the experimental results, it can be seen that the topology of the present invention realizes power factor correction, and the DC voltage output is stable with good steady-state performance.

[0094] The rectifier of the present invention integrates pseudo-totem pole rectification technology and four-level topology technology. Compared with traditional two-level rectifiers, it can effectively reduce the stress of the switch tube, improve the overall efficiency of the system, and does not have the bridge arm shoot-through phenomenon.

Claims

1. A single-phase four-level rectifier power supply based on a pseudo-totem pole structure, characterized in that: The rectifier power supply includes: 8 fully controlled power switches S1~S8, 6 diodes D1~D6, inductors L1 and L2, and capacitors C1~C3; AC power supply g One end is connected to the anode of diode D5 and the cathode of diode D6, and the connection node constitutes terminal n; AC power supply g The other end is connected to one end of the inductor L1 and one end of the inductor L2 to form a connection node; The other end of the inductor L1 is connected to the anode of the diode D1 and the drain of the switch S1, and the connection node constitutes the terminal a; The other end of the inductor L2 is connected to the cathode of the diode D2 and the source of the switch S4, and the connection node constitutes the terminal b; The source of the switch tube S1 is connected to the drain of the switch tube S2 and the anode of the diode D4 respectively; The source of the switch tube S3 is connected to the drain of the switch tube S4 and the cathode of the diode D3 respectively; The anode of diode D3 is connected to the cathode of diode D4, the drain of switch S5, and the source of switch S7 respectively; The source of the switch tube S5 is connected to the source of the switch tube S6; the drain of the switch tube S7 is connected to the drain of the switch tube S8; The drain of the switch tube S6 is connected to the negative electrode of the capacitor C1 and the positive electrode of the capacitor C2 respectively, and the connection node constitutes the end point e; The source of the switch tube S8 is connected to the negative electrode of the capacitor C2 and the positive electrode of the capacitor C3 respectively, and the connection node constitutes the terminal f; The cathode of diode D1 is connected to the drain of switch tube S3, the cathode of diode D5, the positive electrode of capacitor C1, and the load R L The positive electrode, whose connection node constitutes the terminal point p; The source of the switch tube S2 is connected to the anode of the diode D2, the anode of the diode D6, the negative electrode of the capacitor C3, and the load R L The negative electrode, whose connection node constitutes the terminal m; The rectifier power supply includes the following operating modes in CCM mode: Four working modes of the positive half cycle: Mode 1: All switches S1 to S8 are turned off, and the grid current i g Through the inductor L1, a path is formed through the diode D1, capacitors C1, C2, C3, and diode D6; the power supply and inductor L1 together charge the capacitors C1, C2, and C3, and the charging current is equal to i g -i dc and to the load R L Power supply, load current equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =+U dc , voltage u between endpoint b and endpoint N bN =u g ; Mode 2: Switches S1 and S5 are turned on, and the grid current i g Through the inductor L1, a path is formed through the switch tube S1, diode D4, switch tube S5, the body diode on the switch tube S6, capacitors C2, C3, and diode D6; the power supply charges the capacitors C2 and C3, and the charging current is equal to i g -i dc , capacitor C1 discharges to the load, and the load current is equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =+2U dc / 3, voltage u between endpoint b and endpoint N bN =u g ; Mode 3: Switches S1 and S8 are turned on, and the grid current i g Through the inductor L1, a path is formed through the switch tube S1, diode D4, the body diode on the switch tube S7, the switch tube S8, capacitor C3, and diode D6; the power supply charges the capacitor C3, and the charging current is equal to i g -i dc , capacitors C1 and C2 discharge to the load, and the load current is equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =+1U dc / 3, voltage u between endpoint b and endpoint N bN =u g ; Mode 4: Switches S1 and S2 are turned on, and the grid current i g Through the inductor L1, a path is formed through the switch tube S1, switch tube S2, and diode D6, and the AC power supply u g The inductor L1 is charged; the capacitors C1, C2, C3 and the load form another path; the capacitors C1, C2, C3 discharge to the load, and the load current is equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =0, the voltage u between endpoint b and endpoint N bN =u g ; The four working modes of the negative half cycle are similar to the four working modes of the positive half cycle, and the positive and negative half cycle working modes are symmetrical.

2. The single-phase four-level rectifier power supply based on the pseudo-totem pole structure according to claim 1, characterized in that: The diodes D1 and D2, the switches S1 to S4, and the inductors L1 and L2 form a pseudo totem pole structure.

3. The single-phase four-level rectifier power supply based on the pseudo-totem pole structure according to claim 1, characterized in that: The capacitors C1, C2, and C3 are series split capacitors, and the DC bus is composed of C1, C2, and C3. The capacitors C1, C2, and C3 are of the same model. Each capacitor withstands the DC bus voltage U dc One third of the four-level ±1 / 3U dc level.

4. The single-phase four-level rectifier power supply based on the pseudo-totem pole structure according to claim 1, characterized in that: The power switch tubes S1 to S8 are all insulated gate bipolar transistors IGBTs or integrated gate commutated thyristors IGCTs or power field effect transistors MOSFETs.

5. The single-phase four-level rectifier power supply based on a pseudo-totem pole structure according to any one of claims 1 to 4, characterized in that: The rectifier power supply also includes four working modes of the negative half cycle: Mode 5: Switches S3 and S4 are turned on, and the grid current i g A path is formed through diode D5, switch tube S3, switch tube S4, and inductor L2, and the AC power supply u g The inductor L1 is charged; the capacitors C1, C2, C3 and the load form another path; the capacitors C1, C2, C3 discharge to the load, and the load current is equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =0; Mode 6: Switches S4 and S6 are turned on, and the grid current i g A path is formed through diode D5, capacitor C1, switch S6, the body diode on switch S5, diode D3, switch S4, and inductor L2; the power supply charges capacitor C1, and the charging current is equal to -i g -i dc , capacitors C2 and C3 discharge to the load, and the load current is equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-1U dc / 3; Mode 7: Switches S4 and S7 are turned on, and the grid current i g A path is formed through diode D5, capacitors C1 and C2, the body diode on switch S8, switch S7, diode D3, switch S4, and inductor L2; the power supply charges capacitors C1 and C2, and the charging current is equal to -i g -i dc , capacitor C3 discharges to the load, and the load current is equal to i dc ; In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-2U dc / 3; Mode 8: All switches S1 to S8 are turned off, and the grid current i g A path is formed through diode D5, capacitors C1, C2, C3, diode D2, and inductor L2; the power supply and inductor L2 charge capacitors C1, C2, and C3, and the charging current is equal to -i g -i dc and to the load R L Power supply, load current equal to i dc In this mode, the voltage u between terminal a and terminal n is aN =u g , voltage u between endpoint b and endpoint N bN =-U dc .

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