Two-segment dead zone method of novel hybrid clamping type six-level inverter

Abstract

The invention discloses a two-segment dead zone method of a novel hybrid clamping type six-level inverter, and the circuit topology structure of the hybrid clamping type six-level inverter comprises a DC power supply, a DC bus capacitor, a flying capacitor, and a plurality of groups of main switch tubes and clamping switch tubes, wherein every two of the main switch tubes and the clamping switch tubes are complementary. The dead zone time of the hybrid clamping type six-level inverter comprises two segments, and for the state switching process with the dead zone effect, one segment of dead zone is replaced by two segments of dead zones. The invention belongs to the technical field of inverters, and particularly provides a two-stage dead zone method of a novel hybrid clamping type six-level inverter, which is used for solving the problem of distortion of output voltage of a multi-level inverter in dead zone time.

Description

Technical Field

[0001] The invention belongs to the technical field of inverters, and in particular refers to a two-segment dead zone method of a novel hybrid clamped six-level inverter. Background Art

[0002] In order to avoid the direct conduction of the upper and lower tubes during the inverter power period due to delay problems and to prevent the switching devices from being burned out due to direct conduction, a dead zone is usually inserted in the upper and lower tube drive waveforms to reduce the risk of short circuit. After the dead zone is inserted, the dead time is introduced. The so-called dead time refers to the period of time that must pass after the switch tube is turned off before its complementary switch tube can be turned on. This period of time is called the dead time.

[0003] However, during the dead time, the system output voltage is significantly distorted and non-adjacent level switching will cause greater electromagnetic interference, resulting in a dead time effect. The dead time effect causes the output voltage waveform to be distorted, thereby increasing the electromagnetic interference to the outside world. Therefore, a method needs to be taken to solve the dead time effect. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a novel two-stage dead zone method of a hybrid clamped six-level inverter, which is used to solve the problem of output voltage distortion of a multi-level inverter during the dead zone time.

[0005] The technical solutions adopted in this application are as follows:

[0006] The present invention provides a novel hybrid clamped six-level inverter. The circuit topology of the hybrid clamped six-level inverter includes a DC power supply, a DC bus capacitor, a flying capacitor, a plurality of pairs of complementary main switch tubes and clamping switch tubes.

[0007] The topology circuit of the six-level inverter includes:

[0008] The left path is composed of DC bus capacitors C1, C2, and C3 connected in series in the same direction;

[0009] The main switch S 1 , S 2 , S 3 , S 4 The right road is composed of serial connections in the same direction;

[0010] By clamp switch tube S 5 , S 6 Middle route one composed of reverse series connection;

[0011] By clamp switch tube S 7 , S 8 Middle route 2 composed of reverse series connection;

[0012] The flying capacitor C f Connect between middle road 1 and middle road 2.

[0013] In a preferred embodiment, the switch tube adopts an insulated gate bipolar transistor (IGBT) with a built-in reverse diode, and each switch tube is connected in reverse parallel with a diode, that is, the drain of the switch tube is connected to the cathode of the diode, and the source of the switch tube is connected to the anode of the diode.

[0014] As a further elaboration of the scheme, the present scheme discloses a novel hybrid clamped six-level inverter, including a circuit topology structure of the hybrid clamped six-level inverter as described above, and controlling the conduction of the main switch tube and the clamping switch tube through a driving circuit to output a level.

[0015] In a preferred solution, the inverter includes two dead time periods. For a state switching process with a dead time effect, two dead time periods are used instead of one dead time period.

[0016] In the preferred embodiment, the inverter has eight switching states, corresponding to six levels 0, V dc / 5,2V dc / 5,3V dc / 5,4V dc / 5, V dc .

[0017] In this scheme, the on-off states of the switch tubes corresponding to the eight switching states are (1, 1, 0, 0, 1, 0, 1, 0), (0, 1, 0, 0, 1, 1, 0), (1, 0, 1, 0, 1, 0, 1, 0), (0, 1, 0, 0, 0, 1, 1, 1), (0, 1, 0, 1, 0, 1, 0, 1), (0, 0, 1, 0, 0, 1, 1, 1), (0, 0, 1, 0, 0, 1, 1, 1), (0, 0, 1, 1, 0, 1, 0, 1).

[0018] Among them, 1 is on and 0 is off.

[0019] In the preferred embodiment, the eight switching states include V 0 , V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , V 7 The voltage levels corresponding to the above switch states are: 0, V dc / 5,2V dc / 5,2V dc / 5,3V dc / 5,3V dc / 5,4V dc / 5, V dc .

[0020] As a further elaboration of the scheme, the present scheme also discloses a two-stage dead zone compensation method for a novel hybrid clamped six-level inverter, including:

[0021] The switch state V 2 , V 3 and V 4 , V 5 The distinction is determined by their influence on the flying capacitor. i0<0 has a switching state for charging the flying capacitor, which is V 3 and V 5 , followed by V 2 and V 4 .

[0022] The beneficial effects achieved by the present invention using the above scheme are as follows:

[0023] For the state switching process without dead zone effect, the traditional dead zone method is still used. For the state switching process with dead zone effect, the two-segment dead zone method provided by this solution is used to replace the traditional dead zone method, using two-segment dead zones to replace the original one-segment dead zone, which can well solve the dead zone effect while ensuring that the complementary switch tube will not be directly connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the topological structure of the novel hybrid clamped six-level inverter provided by this solution;

[0025] Figure 2 It is the current path of the switching state of the novel hybrid clamped six-level inverter provided by the present solution;

[0026] Figure 3 It is the switching state switching diagram of the novel hybrid clamped six-level inverter provided by this solution;

[0027] Figure 4 The two-stage dead-zone method is applied to V when the output current flows out 6 Convert to V 5 The current path;

[0028] Figure 5 The two-stage dead-zone method is applied to V when the output current flows out 2 Convert to V 1 current path.

[0029] The meanings of the labels are as follows:

[0030] Figure 1 In the middle, 1 represents the left road; 2 represents the middle road consisting of middle road one and middle road two; 3 represents the right road. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] Example 1

[0033] Please refer to Figure 1 As shown, this embodiment provides a novel hybrid clamped six-level inverter, including a hybrid clamped six-level inverter, wherein the circuit topology structure of the hybrid clamped six-level inverter includes a DC power supply, a DC bus capacitor, a flying capacitor, and multiple groups of main switch tubes and clamping switch tubes that are complementary in pairs.

[0034] like Figure 1 As shown, the left circuit is composed of DC bus capacitors C1, C2, and C3 connected in series in the same direction; the main switch tube S 1 , S 2 , S 3 , S 4 The right path is composed of the same direction series connection; the clamp switch tube S 5 , S 6 The middle circuit 1 is composed of reverse series connection; the clamp switch tube S 7 , S 8 The flying capacitor C f Connected between middle path 1 and middle path 2; controls the conduction of the main switch tube and the clamp switch tube to output the electrical level.

[0035] like Figure 1 As shown, the switch tube S 1 The drain of is connected to the positive electrode of the DC bus capacitor C1 and connected to the DC bus voltage V dc The positive electrode, the switch tube S 4 The source of is connected to the negative electrode of the DC bus capacitor C3 and connected to the DC bus voltage V dc negative electrode;

[0036] The potential of output point A is located at the switch tube S 2 The source and S 3 Between the drain electrodes;

[0037] The clamping switch tube S 5 The drain of the capacitor is connected between the negative electrode of the DC bus capacitor C1 and the positive electrode of C2. The clamping switch tube S 5 The source and clamp switch S 6 The source of the clamp switch S 6 The drain of the main switch S 1 The source and S 2 Between the drain electrodes;

[0038] The clamping switch tube S 7The drain of the capacitor C2 is connected between the negative electrode of the DC bus capacitor C2 and the positive electrode of C3. The clamping switch tube S 7 The source and clamp switch S 8 The source of the clamp switch S 8 The drain of the main switch S 3 The source and S 4 Between the drain electrodes;

[0039] The flying capacitor C f The positive electrode and the clamp switch tube S 6 The drain of the flying capacitor C f The negative electrode and the clamp switch tube S 8 The drain is connected.

[0040] Example 2

[0041] like Figure 1 The topology diagram of the novel hybrid clamped six-level inverter is shown in FIG. Figure 2 The 8 switch states shown are V 0 , V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , V 7 , corresponding to six levels 0, V dc / 5,2V dc / 5,3V dc / 5,4V dc / 5, V dc In order to optimize the output voltage harmonic characteristics, the output levels of the previous and next switching states must be adjacent. Under the premise of satisfying the adjacent levels, the optimal switching state is selected by comprehensively considering other parameter indicators.

[0042] In this solution, the on-off states of the switch tube corresponding to the eight switch states are (1, 1, 0, 0, 1, 0, 1, 0), (0, 1, 0, 0, 1, 1, 1, 0), (1, 0, 1, 0, 1, 0), (0, 1, 0, 0, 0, 1, 1, 1), (0, 1, 0, 1, 0, 1, 0, 1), (0, 0, 1, 0, 0, 1, 1, 1), (0, 0, 1, 0, 0, 1, 1, 1), (0, 0, 1, 1, 0, 1, 0, 1). Among them, 1 is on and 0 is off.

[0043] In the preferred embodiment, the eight switching states include V 0 , V 1 , V 2 , V 3 , V 4 , V 5 , V 6, V 7 The voltage levels corresponding to the above switch states are: 0, V dc / 5,2V dc / 5,2V dc / 5,3V dc / 5,3V dc / 5,4V dc / 5, V dc .

[0044] The two-segment dead zone method of the hybrid clamped six-level inverter comprises:

[0045] The dead time of the hybrid clamped six-level inverter includes two sections. For the state switching process with the dead time effect, the two sections of dead time are used to replace it.

[0046] Example 3

[0047] In the traditional dead zone method, the state V 6 Switch to state V 5 For example, simply expressed as V 6 →V 5 , for state V 5 , switch tube S 1 -S 8 The state is (0,1,0,0,1,1,1,0); for state V 6 , switch tube S 1 -S 8 The state of is (1,0,1,0,1,0,1,0). According to the traditional dead zone method, first S 2 and S 6 From on to off, after a period of dead time, the complementary switch S 1 and S 3 From off to on. During the whole process, the switch tube S 1 -S 8 The state of is changed from (0,1,0,0,1,1,1,0) to (0,0,0,0,1,0,1,0) and then to (1,0,1,0,1,0,1,0). It can be seen that during the dead time, only S 5 and S 7 In the on state. When the output current direction is outflow, the current flows through S 5 , S 6 The anti-parallel diode and S 3 The anti-parallel diode, at this time the current path of the system is in the state V 3 Same, its output level is 2V dc / 5. When the output current direction is inflow, the current flows through S 1 and S 2The anti-parallel diode, at this time the current path of the system is in the state V 7 The same, its output level is V dc The entire V 6 →V 5 During the switching process, the output level changes from 4V dc / 5 switch to 3V dc / 5. However, during the dead time, the output level is 2V dc / 5 or V dc , the output voltage can be seen to be obviously distorted, and non-adjacent level switching will cause greater electromagnetic interference.

[0048] Example 4

[0049] like Figure 3 The figure shows the switching state switching diagram of the new hybrid clamped six-level inverter. It can be seen that there are 8 state switching processes, which are Indicates bidirectional switching of states. Since the eight switch tubes of the new hybrid clamped six-level inverter complement each other, the on-off status of each state can be replaced by four independent switches, which are S 1 , S 2 , S 4 , S 5 , similarly, "1" indicates that the switch is on, and "0" indicates that the switch is off.

[0050] Figure 3 The numbers in brackets below each switch state are the on / off status of the four independent switches. 7 (1,1,0,1) indicates that when the new hybrid clamped six-level inverter is in state V 7 When the independent switch S 1 , S 2 , S 4 , S 5 They are on, on, off, on. The remaining four switches are the complementary states of the independent switches.

[0051] Table 1

[0052]

[0053] Using the traditional dead zone method, in all state switching processes, the switching state of the system during the dead zone time is shown in Table 1. From Table 1, it can be seen that using the traditional dead zone method, and There is a dead zone effect in these two state switching processes. In the other state switching processes, the switch state presented in the dead zone time must be the same as the switch state before or after the switching, and there is no dead zone effect.

[0054] V 6 →V 5 For example, analyze V 6 →V 5 The specific operation process of using the two-stage dead zone method.

[0055] When the output current flows out, the specific operation process of the two-stage dead zone method is as follows: the first step is to turn off S 6 , the output current path remains unchanged, and the system is in state V 6 ; After a period of dead time, the second step is to open S 1 , turn off S 2 , at this time the system is in state V 5 ; After a period of dead time, the third step is to open S 3 , the system has completely switched to state V 5 The current path diagram of the entire switching process is shown in Figure 4 As shown in the figure, it can be seen that the dead time is changed from one section to two sections. The first section is the complementary switch S 1 and S 6 The second section is the dead time of the complementary switch S 2 and S 3 The state presented during the first dead time is V 6 The state presented during the second dead time is V 5 , they are all switching states before or after switching, there is no distortion in the output voltage, and the dead zone effect no longer exists.

[0056] When the output current flows in, the first step is to turn off S 2 , at this time the system is in state V 6 ; After a period of dead zone, the second step is to open S 3 , turn off S 6 , at this time the system is in state V 5 ; After a period of dead time, the third step is to open S 1 , the system has completely switched to state V 5 Similarly, the entire switching process not only ensures the dead time of the complementary switch, but also makes the output voltage free of distortion, thus avoiding the dead time effect.

[0057] The above article analyzes V 6 →V 5 The specific operation process of the two-stage dead zone method is, in principle, V 5 →V 6 The two-stage dead zone method operation process is V 6 →V 5 The reverse process is not described here anymore.

[0058] Analysis V 2 →V 1 The specific operation process of using the two-stage dead zone method.

[0059] When the output current flows out, the first step is to turn off S 4 , at this time the current can still flow through S 4 The anti-parallel diode flows, the current path remains unchanged, and the system still presents the state V 2 ; After a period of dead time, the second step is to open S 7 , turn off S 2 , at this time the system is in state V 1 ; After a period of dead time, the third step is to open S 3 , the system has completely switched to state V 1 The current path diagram of the entire switching process is shown in Figure 5 When the output current flows in, the first step is to turn off S 2 , at this time the system is in state V 2 ; After a period of dead time, the second step is to open S 3 , turn off S 4 , at this time the system is in state V 1 ; After a period of dead time, the third step is to open S 7 , at this time the system completely switches to state V 1 .

[0060] Similarly, V 1 →V 2 The operation process of the two-stage dead zone method is V 2 →V 1 The reverse process will not be described in detail.

[0061] In summary, the two-stage dead zone method proposed in the present invention effectively solves the dead zone effect existing when the single-phase novel hybrid clamped six-level inverter adopts the traditional dead zone method when some switch states are switched, and avoids the output voltage distortion during the dead zone time.

[0062] For the state switching process where there is no dead zone effect, the traditional dead zone method is still used. For the state switching process where there is a dead zone effect, the present invention proposes to replace the traditional dead zone method with a two-stage dead zone method. The so-called two-stage dead zone method is to use two sections of dead zones to replace the original one section of dead zone, which can well solve the dead zone effect under the premise of ensuring that the complementary switch tube will not be directly connected. Due to the dead zone effect, the output voltage waveform is distorted, thereby increasing the electromagnetic interference to the outside world. Through the above technical solution conceived by the present invention, compared with the prior art, the two-stage dead zone method provided by the present invention for the new hybrid clamped six-level inverter can effectively solve the dead zone effect.

[0063] It should be noted that although the embodiments of the present invention have been shown and described, for ordinary technicians in this field, without departing from the purpose of the invention, structural methods and embodiments similar to the technical solution are designed without creativity and should all fall within the scope of protection of the present invention.

Claims

1. A novel two-stage dead zone method for a hybrid clamped six-level inverter, comprising a hybrid clamped six-level inverter, wherein the circuit topology of the hybrid clamped six-level inverter comprises a DC power supply, a DC bus capacitor, a flying capacitor, and a plurality of pairs of complementary main switch tubes and clamping switch tubes, and is characterized in that: The DC bus capacitors C1, C2, and C3 are connected in series in the same direction to form the left path; the main switch tubes S1, S2, S3, and S4 are connected in series in the same direction to form the right path; the clamp switch tubes S5 and S6 are connected in series in the opposite direction to form the middle path one; the clamp switch tubes S7 and S8 are connected in series in the opposite direction to form the middle path two; the flying capacitor C f Connected between the middle path 1 and the middle path 2; controlling the conduction of the main switch tube and the clamp switch tube to output the electrical level; The two-segment dead zone method of the hybrid clamped six-level inverter comprises: The dead time of the hybrid clamped six-level inverter includes two sections. For the state switching process with the dead time effect, two sections of dead time are used to replace one section of dead time.

2. The two-segment dead zone method of a novel hybrid clamped six-level inverter according to claim 1, characterized in that: The drain of the switch tube S1 is connected to the positive electrode of the DC bus capacitor C1 and connected to the DC bus voltage V dc The positive electrode of the switch tube S4 is connected to the negative electrode of the DC bus capacitor C3 and connected to the DC bus voltage V dc negative electrode; The drain of the clamp switch tube S5 is connected between the negative electrode of the DC bus capacitor C1 and the positive electrode of C2, the source of the clamp switch tube S5 is connected to the source of the clamp switch tube S6, and the drain of the clamp switch tube S6 is connected between the source of the main switch tube S1 and the drain of S2; The drain of the clamp switch tube S7 is connected between the negative electrode of the DC bus capacitor C2 and the positive electrode of C3, the source of the clamp switch tube S7 is connected to the source of the clamp switch tube S8, and the drain of the clamp switch tube S8 is connected between the source of the main switch tube S3 and the drain of S4; The flying capacitor C f The positive electrode is connected to the drain of the clamp switch tube S6, and the flying capacitor C f The negative electrode is connected to the drain of the clamping switch tube S8.

3. The two-segment dead zone method of a novel hybrid clamped six-level inverter according to claim 2, characterized in that: The hybrid clamped six-level inverter has eight switching states, corresponding to six levels 0, V dc / 5,2V dc / 5,3V dc / 5,4V dc / 5, V dc .

4. The two-segment dead zone method of a novel hybrid clamped six-level inverter according to claim 3, characterized in that: The on-off states of the switch tubes S1, S2, S3, S4, S5, S6, S7, and S8 corresponding to the eight switching states are (1, 1, 0, 0, 1, 0, 1, 0), (0, 1, 0, 0, 1, 1, 0), (1, 0, 1, 0, 1, 0, 1, 0), (0, 1, 0, 0, 0, 1, 1, 1), (0, 1, 0, 1, 0, 1, 0, 1), (0, 0, 1, 0, 0, 1, 1, 1), (0, 0, 1, 0, 0, 1, 1, 1), (0, 0, 1, 1, 0, 1, 0, 1).

5. The two-segment dead zone method of a novel hybrid clamped six-level inverter according to claim 4, characterized in that: The eight switch states include V0, V1, V2, V3, V4, V5, V6, and V7. The voltage levels corresponding to the above switch states are: 0, V dc / 5,2V dc / 5,2V dc / 5,3V dc / 5,3V dc / 5,4V dc / 5, V dc .

6. The two-segment dead zone method of a novel hybrid clamped six-level inverter according to claim 5, characterized in that: The switch states V2, V3 and V4, V5 are distinguished by their effects on the flying capacitor C f The influence of i0<0 on the flying capacitor C f The switching states for charging are V3 and V5, followed by V2 and V4.

7. The two-segment dead zone method of a novel hybrid clamped six-level inverter according to claim 1, characterized in that: The main switch tube and the clamp switch tube adopt insulated gate bipolar transistors with built-in reverse diodes.

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