A hybrid voltage equalization circuit for series wind power converters

Abstract

This invention provides a hybrid voltage equalization circuit for series-connected wind power converters, comprising: an RC coupling branch electrically connected to both a first voltage-stabilizing branch and a second voltage-stabilizing branch; a regulating branch electrically connected to both the first and second voltage-stabilizing branches, and working together with the RC coupling branch to control the voltages of the first and second voltage-stabilizing branches, ensuring that the voltages of the two branches are equal. In practical use, after connecting the first and second voltage-stabilizing branches in parallel to the two series-connected wind power converters, the overall circuit can meet the high voltage withstand requirements, and the voltage imbalance between the two wind power converters is small, with good consistency. The circuit provided by this invention has a simple voltage control method, short control delay, stable voltage after adjustment, and high reliability.

Description

Technical Field

[0001] This invention generally relates to the field of control circuit technology, and more specifically to a hybrid voltage equalization circuit for a series wind power converter. Background Technology

[0002] Against the backdrop of an accelerating global energy transition, the importance of wind power technology is increasingly prominent. As a key component in wind power systems, the performance improvement of wind power converters is crucial for the efficient and stable operation of these systems. In high-voltage, high-capacity wind power converter applications, transistors often need to be connected in series to meet high-voltage operating requirements.

[0003] When wind power converters frequently switch operating states, the electromagnetic environment becomes complex and variable, drive signals are susceptible to interference, and line delays are not negligible. These factors lead to asynchrony of gate drive signals, and passive voltage equalization methods lack active adjustment capabilities, making it impossible to effectively address this situation and thus difficult to maintain voltage balance.

[0004] In existing technologies, complex voltage equalization control strategies often introduce control delays, slowing down the response speed of wind power converters to grid and load changes. This is extremely detrimental to wind power converters that need to maintain stable operation in complex grid environments. In summary, existing voltage equalization technologies in the field of transistor series voltage equalization for wind power converters are insufficient, necessitating innovative and effective hybrid voltage equalization methods to meet the development needs of wind power converters and improve their performance and reliability. Summary of the Invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a hybrid voltage equalization circuit for series wind power converters.

[0006] This invention provides a hybrid voltage equalization circuit for series-connected wind power converters, used to make the voltages of multiple series-connected wind power converters equal, comprising:

[0007] A resistor-capacitor coupling branch, wherein the resistor-capacitor coupling branch has a first terminal, a second terminal, a third terminal, a fourth terminal, and a fifth terminal;

[0008] The first voltage stabilizing branch is electrically connected to the first terminal, the second terminal and the third terminal respectively; the first voltage stabilizing branch is used to connect in parallel with one of the wind power converters.

[0009] The second voltage stabilizing branch is electrically connected to the third, fourth, and fifth terminals respectively; the second voltage stabilizing branch is used to connect in parallel with another wind power converter.

[0010] The regulating branch is electrically connected to the first voltage regulating branch and the second voltage regulating branch respectively, and is used to work together with the RC coupling branch to control the voltage of the first voltage regulating branch and the second voltage regulating branch so that the voltage of the first voltage regulating branch and the second voltage regulating branch are equal.

[0011] According to the technical solution provided by the present invention, the resistor-capacitor coupling branch includes:

[0012] The first coupling branch is electrically connected to the first terminal, the second terminal and the third terminal respectively;

[0013] The second coupling branch is electrically connected to the third terminal, the fourth terminal and the fifth terminal respectively.

[0014] According to the technical solution provided by the present invention, the first coupling branch includes:

[0015] A first resistor is connected between the first terminal and the second terminal;

[0016] The second resistor is connected between the second terminal and the third terminal;

[0017] A first capacitor and a third resistor, wherein one end of the first capacitor is electrically connected to the first terminal and the other end is electrically connected to one end of the third resistor; the other end of the third resistor is electrically connected to the second terminal; and a first node is formed between the third resistor and the first capacitor;

[0018] The second capacitor is electrically connected at both ends to the first node and the third terminal, respectively.

[0019] According to the technical solution provided by the present invention, the second coupling branch includes:

[0020] A fourth resistor is connected between the third terminal and the fourth terminal;

[0021] The fifth resistor is connected between the fourth terminal and the fifth terminal;

[0022] A third capacitor and a sixth resistor, wherein one end of the third capacitor is electrically connected to the third terminal, and the other end is electrically connected to one end of the sixth resistor; the other end of the sixth resistor is electrically connected to the fourth terminal; and a second node is formed between the sixth resistor and the third capacitor;

[0023] The fourth capacitor is electrically connected at both ends to the second node and the fifth terminal, respectively.

[0024] According to the technical solution provided by the present invention, the first voltage stabilizing branch includes:

[0025] A first transistor, wherein the collector of the first transistor is electrically connected to the first terminal and the emitter of the first transistor is electrically connected to the third terminal;

[0026] A first variable resistor, one end of which is electrically connected to the gate of the first transistor; the first variable resistor has a first adjustment terminal; the first adjustment terminal is electrically connected to the control branch; the control branch is used to adjust the resistance value of the first variable resistor.

[0027] The first diode has its anode electrically connected to the other end of the first variable resistor, and its cathode electrically connected to the second terminal.

[0028] According to the technical solution provided by the present invention, the second voltage stabilizing branch includes:

[0029] The second transistor has its collector electrically connected to the first terminal and its emitter electrically connected to the third terminal.

[0030] A second variable resistor, one end of which is electrically connected to the gate of the second transistor; the second variable resistor has a second adjustment terminal; the second adjustment terminal is electrically connected to the control branch; the control branch is used to adjust the resistance value of the second variable resistor;

[0031] The second diode has its anode electrically connected to the other end of the second variable resistor, and its cathode electrically connected to the second terminal.

[0032] According to the technical solution provided by the present invention, the anode of the first diode is also electrically connected to a first bias voltage source; the anode of the second diode is also electrically connected to a second bias voltage source.

[0033] According to the technical solution provided by the present invention, the first voltage stabilizing branch further includes:

[0034] The third diode has its anode electrically connected to the collector of the first transistor and its cathode electrically connected to the emitter of the first transistor.

[0035] The second voltage stabilizing branch also includes:

[0036] A fourth diode, wherein the anode of the fourth diode is electrically connected to the collector of the second transistor, and the cathode of the fourth diode is electrically connected to the emitter of the second transistor.

[0037] According to the technical solution provided by the present invention, the control branch includes:

[0038] A first voltage detector has two detection terminals and a first output terminal; the two detection terminals of the first voltage detector are respectively electrically connected to the collector and emitter of the first transistor.

[0039] The first operational amplifier has its inverting input terminal electrically connected to its first output terminal, and its non-inverting input terminal connected to a reference voltage.

[0040] A first feedback network is electrically connected to the output terminal of the first operational amplifier and the first adjustment terminal, respectively, and is used to adjust the resistance value of the first variable resistor.

[0041] The second voltage detector has two detection terminals and a second output terminal; the two detection terminals of the second voltage detector are respectively electrically connected to the collector and emitter of the second transistor.

[0042] The second operational amplifier has its inverting input terminal electrically connected to its second output terminal, and its non-inverting input terminal connected to a reference voltage.

[0043] The second feedback network is electrically connected to the output terminal of the second operational amplifier and the second adjustment terminal, respectively, and is used to adjust the resistance value of the second variable resistor.

[0044] According to the technical solution provided by the present invention, the first voltage stabilizing branch and / or the second voltage stabilizing branch have multiple branches, which are respectively connected in parallel with multiple wind power converters connected in series, so that the voltage of the multiple wind power converters connected in series is equal.

[0045] The beneficial effects of this invention are as follows:

[0046] The RC coupling branch is electrically connected to both the first and second voltage-stabilizing branches. The regulating branch is also electrically connected to both the first and second voltage-stabilizing branches and works in conjunction with the RC coupling branch to control the voltages of the first and second voltage-stabilizing branches, ensuring that the voltages of the two branches are equal. In practical applications, after connecting the first and second voltage-stabilizing branches in parallel to the two series-connected wind turbine converters, the overall circuit can meet the high voltage withstand requirements, and the voltage imbalance between the two wind turbine converters is small, exhibiting good consistency. The circuit provided by this invention offers a simple voltage control method, short control delay, stable voltage after adjustment, and high reliability. Attached Figure Description

[0047] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0048] Figure 1 This is a schematic diagram of a hybrid voltage equalization circuit;

[0049] Figure 2 This is another schematic diagram of a hybrid voltage equalization circuit;

[0050] Figure 3 Comparison of voltages during the turn-off phase before connecting to the hybrid voltage equalization circuit;

[0051] Figure 4 Comparison of voltages during the turn-off phase after connecting to the hybrid voltage equalization circuit;

[0052] Wherein: 1. RC coupling branch; 2. First voltage regulation branch; 3. Second voltage regulation branch; 4. Regulation branch; 5. First resistor; 6. Second resistor; 7. First capacitor; 8. Third resistor; 9. Second capacitor; 10. First node; 11. Fourth resistor; 12. Fifth resistor; 13. Third capacitor; 14. Sixth resistor; 15. Fourth capacitor; 16. Second node; 17. First transistor; 18. First variable resistor; 19. First adjustment terminal; 20. First diode; 21. Second transistor; 22. Second variable resistor; 23. Second adjustment terminal; 24. Second diode; 25. First bias voltage source; 26. Second bias voltage source; 27. Third diode; 28. Fourth diode; 29. ​​First voltage detector; 30. First output terminal; 31. First operational amplifier; 32. First feedback network; 33. Second voltage detector; 34. Second output terminal; 35. Second operational amplifier; 36. Second feedback network;

[0053] 37. DC power supply; 38. Inductor; 39. Seventh resistor; 40. Fifth diode;

[0054] 01. First terminal; 02. Second terminal; 03. Third terminal; 04. Fourth terminal; 05. Fifth terminal. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0056] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0057] Please refer to Figure 1-2 In an operational amplifier, a negative sign indicates the inverting input, and a positive sign indicates the non-inverting input. Uref This indicates the reference voltage. All transistors are Insulated Gate Bipolar Transistors (IGBTs).

[0058] This invention provides a hybrid voltage equalization circuit for series-connected wind power converters, used to make the voltages of multiple series-connected wind power converters equal, comprising:

[0059] The resistor-capacitor coupling branch 1 has a first terminal 01, a second terminal 02, a third terminal 03, a fourth terminal 04, and a fifth terminal 05.

[0060] The first voltage stabilizing branch 2 is electrically connected to the first terminal 01, the second terminal 02 and the third terminal 03 respectively; the first voltage stabilizing branch 2 is used to be connected in parallel with one of the wind power converters.

[0061] The second voltage stabilizing branch 3 is electrically connected to the third terminal 03, the fourth terminal 04 and the fifth terminal 05 respectively; the second voltage stabilizing branch 3 is used to connect in parallel with another wind power converter;

[0062] The regulating branch 4 is electrically connected to the first voltage regulating branch 2 and the second voltage regulating branch 3 respectively, and is used to work together with the RC coupling branch 1 to control the voltage of the first voltage regulating branch 2 and the second voltage regulating branch 3 so that the voltage of the first voltage regulating branch 2 and the second voltage regulating branch 3 are equal.

[0063] Furthermore, the first voltage stabilizing branch 2 and / or the second voltage stabilizing branch 3 have multiple branches, which are respectively connected in parallel with multiple wind power converters connected in series, so that the voltage of the multiple wind power converters connected in series is equal.

[0064] In some implementations, if it is necessary to equalize the voltage of multiple wind power converters, the total number of the first voltage stabilizing branch 2 and the second voltage stabilizing branch 3 is the same as the number of wind power converters; the resistor-capacitor coupling branch 1 and the control branch 4 are also connected to multiple first voltage stabilizing branches 2 and second voltage stabilizing branches 3.

[0065] Multiple first voltage stabilizing branches 2 and second voltage stabilizing branches 3 are connected in parallel in sequence and are respectively connected in parallel at both ends of multiple wind power converters.

[0066] In practical use, after the hybrid voltage equalization circuit provided by this invention is connected to the overall circuit, each wind power converter in the entire circuit system can meet the high voltage withstand requirements, and the voltage imbalance between multiple wind power converters is small and the consistency is good.

[0067] The circuit provided by this invention has a simple method for controlling voltage, short control delay, stable voltage after adjustment, and high reliability.

[0068] refer to Figure 3 This is a comparison diagram of the voltage during the turn-off phase before connecting to the hybrid voltage equalization circuit; Figure 4 This is a comparison diagram of the voltage during the turn-off phase after connecting to the hybrid voltage equalization circuit.

[0069] Figure 3-4 In the diagram, U1 and U2 represent the voltages of two wind power converters, respectively. The horizontal axis represents time, and the vertical axis represents voltage U, with the unit being V.

[0070] The voltage change is significant during the turn-off phase before connecting to the hybrid voltage equalization circuit, such as... Figure 3 As shown;

[0071] The voltage change during the turn-off phase is significantly reduced after connecting the hybrid voltage equalization circuit, such as... Figure 4 As shown.

[0072] The following circuit design uses two wind power converters as an example:

[0073] In this embodiment, voltage equalization can be performed on two wind power converters connected in series. The circuit structure design of the first voltage stabilizing branch 2 and the second voltage stabilizing branch 3 is the same.

[0074] Furthermore, the RC coupling branch 1 includes:

[0075] The first coupling branch is electrically connected to the first terminal 01, the second terminal 02 and the third terminal 03 respectively.

[0076] The second coupling branch is electrically connected to the third terminal 03, the fourth terminal 04 and the fifth terminal 05 respectively.

[0077] Furthermore, the first coupling branch includes:

[0078] The first resistor 5 is connected between the first terminal 01 and the second terminal 02;

[0079] The second resistor 6 is connected between the second terminal 02 and the third terminal 03;

[0080] A first capacitor 7 and a third resistor 8 are connected, with one end of the first capacitor 7 electrically connected to the first terminal 01 and the other end electrically connected to one end of the third resistor 8; the other end of the third resistor 8 is electrically connected to the second terminal 02; and a first node 10 is located between the third resistor 8 and the first capacitor 7.

[0081] The second capacitor 9 is electrically connected at both ends to the first node 10 and the third terminal 03, respectively.

[0082] Furthermore, the second coupling branch includes:

[0083] The fourth resistor 11 is connected between the third terminal 03 and the fourth terminal 04;

[0084] The fifth resistor 12 is connected between the fourth terminal 04 and the fifth terminal 05;

[0085] A third capacitor 13 and a sixth resistor 14 are connected, with one end of the third capacitor 13 electrically connected to the third terminal 03 and the other end electrically connected to one end of the sixth resistor 14; the other end of the sixth resistor 14 is electrically connected to the fourth terminal 04; a second node 16 is located between the sixth resistor 14 and the third capacitor 13.

[0086] The fourth capacitor 15 is electrically connected at both ends to the second node 16 and the fifth terminal 05, respectively.

[0087] Specifically, the first resistor 5 and the fourth resistor 11 have the same resistance value, the second resistor 6 and the fifth resistor 12 have the same resistance value, and the third resistor 8 and the sixth resistor 14 have the same resistance value.

[0088] The capacitance values ​​of the first capacitor 7 and the third capacitor 13 are different, while the capacitance values ​​of the second capacitor 9 and the fourth capacitor 15 are the same.

[0089] Furthermore, the first voltage stabilizing branch 2 includes:

[0090] The first transistor 17 has its collector electrically connected to the first terminal 01 and its emitter electrically connected to the third terminal 03.

[0091] A first variable resistor 18, one end of which is electrically connected to the gate of the first transistor 17; the first variable resistor 18 has a first adjustment terminal 19; the first adjustment terminal 19 is electrically connected to the control branch 4; the control branch 4 is used to adjust the resistance value of the first variable resistor 18.

[0092] The first diode 20 has its anode electrically connected to the other end of the first variable resistor 18, and its cathode electrically connected to the second terminal 02.

[0093] Furthermore, the second voltage stabilizing branch 3 includes:

[0094] The second transistor 21 has its collector electrically connected to the first terminal 01 and its emitter electrically connected to the third terminal 03.

[0095] A second variable resistor 22, one end of which is electrically connected to the gate of the second transistor 21; the second variable resistor 22 has a second adjustment terminal 23; the second adjustment terminal 23 is electrically connected to the control branch 4; the control branch 4 is used to adjust the resistance value of the second variable resistor 22.

[0096] The second diode 24 has its anode electrically connected to the other end of the second variable resistor 22, and its cathode electrically connected to the second terminal 02.

[0097] Furthermore, the anode of the first diode 20 is also electrically connected to a first bias voltage source 25; the anode of the second diode 24 is also electrically connected to a second bias voltage source 26.

[0098] Furthermore, the first voltage stabilizing branch 2 also includes:

[0099] The third diode 27 has its anode electrically connected to the collector of the first transistor 17, and its cathode electrically connected to the emitter of the first transistor 17.

[0100] The second voltage stabilizing branch 3 also includes:

[0101] The fourth diode 28 has its anode electrically connected to the collector of the second transistor 21, and its cathode electrically connected to the emitter of the second transistor 21.

[0102] Furthermore, the control branch 4 includes:

[0103] A first voltage detector 29 has two detection terminals and a first output terminal 30; the two detection terminals of the first voltage detector 29 are electrically connected to the collector and emitter of the first transistor 17, respectively.

[0104] The first operational amplifier 31 has its inverting input terminal electrically connected to the first output terminal 30, and its non-inverting input terminal connected to a reference voltage.

[0105] The first feedback network 32 is electrically connected to the output terminal of the first operational amplifier 31 and the first adjustment terminal 19, respectively, and is used to adjust the resistance value of the first variable resistor 18.

[0106] The second voltage detector 33 has two detection terminals and a second output terminal 34; the two detection terminals of the second voltage detector 33 are electrically connected to the collector and emitter of the second transistor 21, respectively.

[0107] The second operational amplifier 35 has its inverting input terminal electrically connected to the second output terminal 34, and its non-inverting input terminal connected to a reference voltage.

[0108] The second feedback network 36 is electrically connected to the output terminal of the second operational amplifier 35 and the second adjustment terminal 23, respectively, and is used to adjust the resistance value of the second variable resistor 22.

[0109] Specifically, in practical applications, the first terminal 01 and the third terminal 03 are connected to the two ends of one of the wind power converters, the third terminal 03 and the fifth terminal 05 are connected to the two ends of the other wind power converter; the fifth terminal 05 is grounded.

[0110] To test the usability of the circuit of this invention, a test branch can be connected between the first terminal 01 and the fifth terminal 05. The test branch includes: a DC power supply 37, an inductor 38, and a seventh resistor 39 connected in series; it also includes a fifth diode 40, with the anode of the fifth diode 40 connected between the DC power supply 37 and the inductor 38, and the cathode connected between the seventh resistor 39 and the first terminal 01.

[0111] Therefore, the first voltage detector 29 can detect the voltage between the first terminal 01 and the third terminal 03; the second voltage detector 33 can detect the voltage between the third terminal 03 and the fifth terminal 05; if the voltages detected by the two parts are equal, it means that the circuit of the present invention effectively controls the voltage and ensures the equality of the voltage.

[0112] Based on the above circuit design, the working principle includes three cases: passive control of transient voltage equalization during shutdown, active control of transient voltage equalization during shutdown, and static voltage equalization control.

[0113] To reflect the dynamic voltage imbalance between the two transistors, when the first transistor 17 is turned on and the second transistor 21 is turned off, the voltages on both the second capacitor 9 and the fourth capacitor 15 are equal to the voltage of the DC power supply 37. The voltage across the second capacitor 9 and the fourth capacitor 15 is half of the voltage across the first capacitor 7 and the third capacitor 13, while the voltage across the second capacitor 9 and the fourth capacitor 15 is 100 times the voltage across the first capacitor 7 and the third capacitor 13.

[0114] The voltages across the second capacitor 9 and the fourth capacitor 15 will not change significantly in a short period of time; therefore, the second capacitor 9 and the fourth capacitor 15 can be considered as two constant voltage sources. During initial stable conduction, the conduction voltages of the first transistor 17 and the second transistor 21 are 0, and the second capacitor 9 and the fourth capacitor 15 are considered as voltage sources, with the voltage being the DC power supply voltage 37. Half of the voltage of the first capacitor 7 and the third capacitor 13 is equal to the voltage of the DC power supply 37. Half of the voltage, but in the opposite direction; both the first diode 20 and the second diode 24 are reverse-biased and cut off.

[0115] When the shutdown begins, the first transistor 17 turns off first, and its voltage rises. The voltage at the second transistor 21 then exceeds the voltage of the DC power supply 37. When the voltage is half of the rated voltage, the fourth capacitor 15 activates, turning on the second diode 24. The voltage on the fourth capacitor 15 causes the gate of the second transistor 21 to briefly turn on, resulting in a drop in terminal voltage. As the voltage on the fourth capacitor 15 decreases, the terminal voltage of the first transistor 17 increases. After multiple cycles, both transistors enter a turn-off steady state. The same applies when the second transistor 21 turns on and the first transistor 17 turns off.

[0116] The methods for switching off transient equalization passive control, switching off transient equalization active control, and static equalization control include the following steps:

[0117] S1, Transient Voltage Equalization Passive Control for Turn-Off: When the first transistor 17 and the second transistor 21 enter the turn-off process, a voltage sensor continuously monitors the change in their terminal voltage. Once the terminal voltage starts to rise and exceeds... Half of the circuit is used to dynamically equalize the voltage of the second capacitor 9 and the fourth capacitor 15 with appropriate parameters, as well as a high-frequency fast recovery second diode 24, so that the fourth capacitor 15 starts to charge. Its voltage change changes the gate voltage of the corresponding device through a specific circuit connection. The gate voltage makes it briefly conduct, and the terminal voltage drops.

[0118] S2, Transient voltage equalization active control during transistor turn-off: During transistor turn-off, the voltage between the first connection terminal 01 and the third connection terminal 03, and between the third connection terminal 03 and the fifth connection terminal 05, is monitored in real time. Through the first feedback network 32 and the second feedback network 36, With the preset turn-off voltage threshold When comparing, At the same time, the values ​​of the first variable resistor 18 and the second variable resistor 22 are adjusted to change the gate voltage change rate of the transistor, thereby changing the switching speed of the transistor and making the turn-off voltage tend to be balanced.

[0119] Specifically, the variable resistor is a digital potentiometer type.

[0120] The feedback network includes interconnected DC voltage sources and controlled current sources. The output current of the controlled current source varies with the output signal of the operational amplifier.

[0121] Therefore, the resistance value of the variable resistor can be adjusted by controlling the output current of the feedback network, ultimately achieving the effect of voltage adjustment.

[0122] S3, static voltage equalization control, accurately detects the steady-state leakage current of each transistor in the off state and determines its minimum leakage current. and maximum leakage current Based on the number of series-connected wind power converters n DC power supply 37V And set the voltage on the first capacitor 7 and the third capacitor 13, and accurately calculate the values ​​of the first resistor 5 and the fourth resistor 11;

[0123] Then, the first resistor 5 and the fourth resistor 11 are connected in parallel between the first terminal 01 and the third terminal 03, and between the third terminal 03 and the fifth terminal 05, respectively.

[0124] The voltages of the second capacitor 9 and the fourth capacitor 15 remain essentially constant when the first transistor 17 and the second transistor 21 are switched on and off; the voltages of the first capacitor 7 and the third capacitor 13 change with the switching of the first transistor 17 and the second transistor 21.

[0125] The capacitance values ​​of the second capacitor 9 and the fourth capacitor 15 need to be much larger than the capacitance values ​​of the first capacitor 7 and the third capacitor 13, so as to balance the voltage of each transistor in the off state.

[0126] In S1, the formula for calculating the reverse recovery time of the first diode 20 and the second diode 24 can be expressed as:

[0127] Formula 1;

[0128] in, It is the reverse recovery time of the diode. It is the rate of change of current. It stores electrical charge. It is the reverse recovery current of the diode.

[0129] If the transient voltage balancing effect during shutdown is not ideal, the capacitor value or diode parameters need to be finely adjusted according to the specific situation.

[0130] During transistor turn-off, the voltage between the first terminal 01 and the third terminal 03 is: ,when > At that time, the outflow current of the second capacitor 9 The calculation formula can be expressed as:

[0131] Formula 2;

[0132] in, The second resistor is 6. The third resistor is 8.

[0133] > At that time, the outflow current of the fourth capacitor 15 The calculation formula can be expressed as:

[0134] Formula 3;

[0135] in, The fifth resistor is 12. The sixth resistor is 14.

[0136] The current flowing into the second capacitor 9 The calculation formula can be expressed as:

[0137] Formula 4;

[0138] in The voltage across the second capacitor 9 is... The voltage change rate of the second capacitor 9.

[0139] The current flowing into the fourth capacitor 15 The calculation formula can be expressed as:

[0140] Formula 5;

[0141] in The voltage across the fourth capacitor 15 is... The voltage change rate of the fourth capacitor 15.

[0142] Adjust the capacitance values ​​of the second capacitor 9 and the fourth capacitor 15 to optimize the transient voltage equalization effect during shutdown, ensuring that the voltage of each transistor can quickly reach a balanced state during shutdown, and reducing voltage spikes and imbalances.

[0143] Simultaneously, a current feedback mechanism is introduced, with a high-precision current sensor connected in series in the charging circuit of the second capacitor 9 and the fourth capacitor 15 to monitor the current in real time. and The charging feedback coefficients of the second capacitor 9 and the fourth capacitor 15 are: The formula for calculating the feedback current can be expressed as:

[0144] Formula Six;

[0145] in, This is the feedback current of the second capacitor 9. This is the feedback current of the fourth capacitor 15.

[0146] The feedback network is used to dynamically adjust the charging process of the second capacitor 9 and the fourth capacitor 15; when Exceeding the preset current threshold At that time, by adjusting the equivalent resistance connected in series with the second capacitor 9 and the fourth capacitor 15 To control the charging current.

[0147] The initial value of the equivalent resistance of the second capacitor 9 Equal to the sum of the resistance values ​​of the second resistor 6 and the third resistor 8; updated equivalent resistance The value is represented as:

[0148] Formula 7.

[0149] The equivalent resistance of the fourth capacitor 15 in series Similarly.

[0150] In S2, the formula for adjusting the first variable resistor 18 can be expressed as:

[0151] Formula 8.

[0152] in, The adjusted resistance value of the first variable resistor 18. The initial resistance value of the first variable resistor 18. To increase the feedback gain, the resistance of the first variable resistor 18 is adjusted to change the rate of change of the transistor's gate voltage. , The gate voltage is used to change the switching rate of the transistor, thereby balancing the turn-off voltage; the same principle applies to adjusting the resistance of the second variable resistor 22.

[0153] In S3, regarding the selection of the static voltage equalizing resistor and the dynamic voltage equalizing capacitor, the formula for calculating the resistance value of the first resistor 5 can be expressed as:

[0154] Formula Nine.

[0155] in, The voltage of the first capacitor 7 is... n This indicates the number of wind power converters connected in series.

[0156] Precise calculation The value of is determined, and then the calculated static voltage equalization resistor is reliably connected in parallel across the collector and emitter of each transistor to balance the voltage of each transistor in the off state.

[0157] The capacitance values ​​of the second capacitor 9 and the fourth capacitor 15 remain essentially unchanged when the first transistor 17 and the second transistor 21 are switched on and off; the capacitance values ​​of the second capacitor 9 and the fourth capacitor 15 are much greater than the capacitance values ​​of the first capacitor 7 and the third capacitor 13.

[0158] The capacitance value of the second capacitor 9 According to the formula, it can be expressed as:

[0159] Formula 10.

[0160] in, This is the DC power supply voltage. This represents the maximum charge of the second capacitor 9 during the charging process.

[0161] The capacitance value of the fourth capacitor 15 According to the formula, it can be expressed as:

[0162] Formula 11.

[0163] in, The voltage across the third capacitor 13. This represents the maximum charge of the fourth capacitor 15 during the charging process.

[0164] In a control strategy involving multiple transistors connected in series, an average control strategy is employed. The average voltage of all parallel devices is calculated, and the formula for calculating the average voltage can be expressed as:

[0165] Formula twelve.

[0166] in, The average voltage is ultimately used as the reference voltage. n This refers to the number of wind turbine converters connected in series. For the first j The voltage of the wind power converter.

[0167] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A hybrid voltage equalization circuit for a series wind power converter, characterized in that, include: The resistor-capacitor coupling branch (1) has a first terminal (01), a second terminal (02), a third terminal (03), a fourth terminal (04), and a fifth terminal (05). The first voltage stabilizing branch (2) is electrically connected to the first terminal (01), the second terminal (02) and the third terminal (03) respectively; the first voltage stabilizing branch (2) is used to connect in parallel with one of the wind power converters; The second voltage stabilizing branch (3) is electrically connected to the third terminal (03), the fourth terminal (04) and the fifth terminal (05) respectively; the second voltage stabilizing branch (3) is used to connect in parallel with another wind power converter; The regulating branch (4) is electrically connected to the first voltage regulating branch (2) and the second voltage regulating branch (3) respectively, and is used to work together with the resistor-capacitor coupling branch (1) to control the voltage of the first voltage regulating branch (2) and the second voltage regulating branch (3) so that the voltage of the first voltage regulating branch (2) and the second voltage regulating branch (3) are equal.

2. The hybrid voltage equalization circuit for a series wind power converter according to claim 1, characterized in that, The resistor-capacitor coupling branch (1) includes: The first coupling branch is electrically connected to the first terminal (01), the second terminal (02) and the third terminal (03) respectively; The second coupling branch is electrically connected to the third terminal (03), the fourth terminal (04) and the fifth terminal (05) respectively.

3. A hybrid voltage equalization circuit for a series wind power converter according to claim 2, characterized in that, The first coupling branch includes: The first resistor (5) is connected between the first terminal (01) and the second terminal (02); The second resistor (6) is connected between the second terminal (02) and the third terminal (03); A first capacitor (7) and a third resistor (8) are connected. One end of the first capacitor (7) is electrically connected to the first terminal (01), and the other end is electrically connected to one end of the third resistor (8). The other end of the third resistor (8) is electrically connected to the second terminal (02). A first node (10) is located between the third resistor (8) and the first capacitor (7). The second capacitor (9) is electrically connected at both ends to the first node (10) and the third terminal (03), respectively.

4. A hybrid voltage equalization circuit for a series wind power converter according to claim 2, characterized in that, The second coupling branch includes: A fourth resistor (11) is connected between the third terminal (03) and the fourth terminal (04); The fifth resistor (12) is connected between the fourth terminal (04) and the fifth terminal (05); A third capacitor (13) and a sixth resistor (14) are connected, with one end of the third capacitor (13) electrically connected to the third terminal (03) and the other end electrically connected to one end of the sixth resistor (14); the other end of the sixth resistor (14) is electrically connected to the fourth terminal (04); and a second node (16) is located between the sixth resistor (14) and the third capacitor (13). The fourth capacitor (15) is electrically connected at both ends to the second node (16) and the fifth terminal (05), respectively.

5. A hybrid voltage equalization circuit for a series wind power converter according to claim 1, characterized in that, The first voltage-stabilized branch (2) includes: The first transistor (17) has its collector electrically connected to the first terminal (01) and its emitter electrically connected to the third terminal (03). A first variable resistor (18) is electrically connected at one end to the gate of the first transistor (17); the first variable resistor (18) has a first adjustment terminal (19); the first adjustment terminal (19) is electrically connected to the control branch (4); the control branch (4) is used to adjust the resistance value of the first variable resistor (18). The first diode (20) has its anode electrically connected to the other end of the first variable resistor (18), and its cathode electrically connected to the second terminal (02).

6. A hybrid voltage equalization circuit for a series wind power converter according to claim 5, characterized in that, The second voltage stabilizing branch (3) includes: The second transistor (21) has its collector electrically connected to the first terminal (01) and its emitter electrically connected to the third terminal (03). A second variable resistor (22) is connected at one end to the gate of the second transistor (21); the second variable resistor (22) has a second adjustment terminal (23); the second adjustment terminal (23) is connected to the control branch (4); the control branch (4) is used to adjust the resistance value of the second variable resistor (22); The second diode (24) has its anode electrically connected to the other end of the second variable resistor (22), and its cathode electrically connected to the second terminal (02).

7. A hybrid voltage equalization circuit for a series wind power converter according to claim 6, characterized in that, The anode of the first diode (20) is also electrically connected to a first bias voltage source (25); the anode of the second diode (24) is also electrically connected to a second bias voltage source (26).

8. A hybrid voltage equalization circuit for a series wind power converter according to claim 6, characterized in that, The first voltage stabilizing branch (2) also includes: The anode of the third diode (27) is electrically connected to the collector of the first transistor (17), and the cathode of the third diode (27) is electrically connected to the emitter of the first transistor (17). The second voltage stabilizing branch (3) also includes: The fourth diode (28) has its anode electrically connected to the collector of the second transistor (21) and its cathode electrically connected to the emitter of the second transistor (21).

9. A hybrid voltage equalization circuit for a series wind power converter according to claim 6, characterized in that, The control branch (4) includes: A first voltage detector (29) has two detection terminals and a first output terminal (30); the two detection terminals of the first voltage detector (29) are electrically connected to the collector and emitter of the first transistor (17), respectively. The first operational amplifier (31) has its inverting input terminal electrically connected to the first output terminal (30), and its non-inverting input terminal connected to the reference voltage. The first feedback network (32) is electrically connected to the output terminal of the first operational amplifier (31) and the first adjustment terminal (19) respectively, and is used to adjust the resistance value of the first variable resistor (18); The second voltage detector (33) has two detection terminals and a second output terminal (34); the two detection terminals of the second voltage detector (33) are electrically connected to the collector and emitter of the second transistor (21), respectively. The second operational amplifier (35) is electrically connected to the second output terminal (34) and the non-inverting input terminal is connected to the reference voltage. The second feedback network (36) is electrically connected to the output terminal of the second operational amplifier (35) and the second adjustment terminal (23) respectively, and is used to adjust the resistance value of the second variable resistor (22).

10. A hybrid voltage equalization circuit for a series wind power converter according to claim 1, characterized in that, The first voltage stabilizing branch (2) and / or the second voltage stabilizing branch (3) have multiple branches, which are used to connect in parallel with multiple wind power converters connected in series, so that the voltage of the multiple wind power converters connected in series is equal.

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