Full-bridge inverter output ripple cancellation network and coupling inductor design method thereof

Abstract

The invention discloses a full-bridge inverter output ripple offset network and a coupling inductor design method thereof. The full-bridge inverter output ripple offset network comprises a full-bridge circuit which is electrically connected with a coupling inductor; the first upper port is electrically connected with the dotted terminal of the first coupling winding, and the synonym terminal of the first coupling winding is electrically connected with the synonym terminal of the third coupling winding, one end of the output capacitor and the second upper port; the first lower port is electrically connected with the synonym terminal of the second coupling winding, and the dotted terminal of the second coupling winding is electrically connected with one end of the ripple capacitor, the other end of the output capacitor and the second lower port. The ripple counteracting network provided by the invention can effectively reduce the amplitude of the output ripple, suppress higher harmonics and realize low-distortion harmonic output under the condition that the volume of a filter is not obviously increased in a manner of transferring high-frequency ripple current through a coupling winding; according to the design method of the coupling inductor, the most common circular magnetic ring is used for inductor winding, and accurate control over self inductance and mutual inductance of the coupling inductor can be conveniently achieved.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering, and in particular to a full-bridge inverter output ripple cancellation network. Background Technology

[0002] Full-bridge inverters have a wide range of applications. Their core principle is to generate an AC voltage waveform at the output by controlling the on / off state of switching devices. The high-frequency switching of these devices introduces high-order harmonics into the output waveform. These harmonics can degrade equipment performance, causing overheating, resonance, and in severe cases, even damage the equipment. Furthermore, applications such as power supplies for precision electronic equipment and radar systems place even higher demands on the low-distortion harmonic output of full-bridge inverters. Therefore, eliminating high-order harmonics and ensuring low-distortion harmonic output is an important research topic for full-bridge inverters.

[0003] To suppress higher harmonics, a common method is to use LC filters with low cutoff frequencies (such as...). Figure 1 (As shown) Alternatively, the switching frequency can be increased. Filters with low cutoff frequencies can effectively reduce the amplitude of output ripple, thereby reducing the content of higher harmonics. However, this increases the size of the converter, reduces power density, and since the frequency of output higher-order ripple is mainly concentrated at the switching frequency, traditional filters struggle to filter out this sub-ripple. Increasing the switching frequency increases switching losses, exacerbates device heating, increases heat dissipation pressure, and enhances high-frequency noise radiation from the device. It also challenges the high-frequency characteristics of inductors and capacitors. Summary of the Invention

[0004] To address the aforementioned issues, this invention discloses a full-bridge inverter output ripple cancellation network. Compared to traditional filters employing low cutoff frequencies, this network offers significant advantages in power density and ripple cancellation effectiveness. Compared to methods that increase the switching frequency to reduce output ripple amplitude, it offers significant advantages in terms of device losses and EMI characteristics.

[0005] To achieve the above object, the technical solution of the present invention is: A full-bridge inverter output ripple cancellation network includes a full-bridge circuit, wherein the full-bridge circuit is electrically connected to a first upper port. p 11 and the first port p 12 First upper port p 11 and the first port p 12 Electrically connected coupling inductor; the coupling inductor includes a first coupling winding. L 1 Second coupling winding L 2 and the third coupling winding L3 Among them, the first coupling winding L 2 Second coupling winding L 2 The coupling coefficient is 1; assume the third coupling winding L 3 self-perception Third coupling winding L 3 Coupled with the first winding L 1 Second coupling winding L 2 The mutual inductance is ,but and satisfy: ; Among them, the first upper port p 11 Electrical connection to the first coupling winding L 1 The same-named terminal, the first coupling winding L 1 The third coupling winding is connected to the opposite-named terminal. L 3 heteronym terminals, output capacitor C 2 One end and the second upper port p 21 First lower port p 12 Electrical connection to the second coupling winding L 2 The opposite end, the second coupling winding L 2 The same-name terminal connection ripple capacitor C One end of 1, output capacitor C The other end of 2 and the second lower port p 22 Third coupling winding L 3 The same-name terminal connection ripple capacitor C The other end of 1.

[0006] A further improvement is made to the third coupling winding. L 3 Coupled with the first winding L 1 and the second coupling winding L 2 Coupling coefficient for: ; For the first coupling windingL 2 and the second coupling winding L 2 Self-perception; Critical mutual inductance coefficient for: ; in, .

[0007] A further improvement is made to the third coupling winding. L 3 With ripple capacitor C 1. A series resonance forms a notch filter network; the notch frequency of the notch filter network... for: ; in, Ripple capacitor C A tolerance value of 1.

[0008] Further improvements include the output capacitor. C 2 capacitance values Ripple capacitor C A capacitance of 1 ,but .

[0009] A further improvement is made to the full-bridge circuit, which includes a first switching transistor. Second switching transistor Third switching transistor and the fourth switching transistor The first switching transistor The source of the second switching transistor is connected. The drain and the first upper port First switching transistor The drain of the third switching transistor is connected. The drain of the third switching transistor The source of the fourth switch is connected. The drain and the first lower port Fourth switching transistor The source of the second switching transistor is connected. The source pole.

[0010] Further improvements, the first switching transistor Second switching transistor Third switching transistor and the fourth switching transistor All are MOSFETs.

[0011] A method for designing a coupled inductor, wherein the coupled inductor is as described above, includes the following steps: Step 1: Stack identical magnetic rings A1 and B2 to form a stacked structure; Step 2, First coupling winding L 1 Second coupling winding L 2 and the third coupling winding L 3 Three strands are wound together on a stacked structure, and then wound... Turns; Step 3, First coupling winding L 1 Second coupling winding L 2 Two additional strands are wound in parallel on magnetic ring A1. Turns, third coupling winding L 3 Additional windings are made on magnetic ring B2 Turns; Step 4: Change the number of turns To adjust the coupling coefficient , making .

[0012] Further improvements can be made by changing the number of turns. At that time, by adjusting the number of turns This makes the first coupling winding L 1 Second coupling winding L 2 Each person's self-perceived sense Keep it unchanged, adjust the number of turns To ensure the third coupling winding L 3 Self-sensory quantity constant.

[0013] Advantages of this invention: The ripple cancellation network proposed in this invention can effectively reduce the output ripple amplitude and suppress high-order harmonics without significantly increasing the size of the filter by transferring high-frequency ripple current through coupling windings. The proposed coupling inductor design method uses the most common circular magnetic ring for inductor winding, which can easily achieve precise control of the self-inductance and mutual inductance of the coupling inductor. Attached Figure Description

[0014] Figure 1 The output of a traditional full-bridge inverter is connected to a low-pass LC filter.

[0015] Figure 2 This invention proposes a full-bridge inverter output ripple cancellation network.

[0016] Figure 3This is the key waveform of the ripple cancellation network proposed in this invention.

[0017] Figure 4 This is the equivalent network after decoupling the full-bridge inverter output ripple cancellation network proposed in this invention.

[0018] Figure 5 The gain transfer function of the ripple cancellation network in the embodiment. The amplitude-frequency curve.

[0019] Figure 6 This is a schematic diagram of the winding cross-winding optimization design method based on double magnetic rings proposed in this invention.

[0020] Figure 7 Mutual inductance coefficient in the embodiment , and Follow A changing curve.

[0021] Figure 8 The number of turns in the example and The effect of rounding on the self-inductance and mutual inductance coefficients of windings. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0023] like Figure 2 As shown, this invention proposes a full-bridge inverter output ripple cancellation network, which includes two ports, namely port 1. p 1 and port p 2. Port p 1 includes the first upper port p 11 and the first port p 12 ,port p 2 includes the second upper port p 21 Second lower port p 22 The coupling winding L 1 and L 2 represents two fully coupled windings with a coupling coefficient of 1. L 3 and ripple capacitor C 1. Form a high-frequency ripple absorption circuit to absorb ripple from the port.p 1's high-frequency current ripple is transferred to L 3 and C In branch 1, the secondary ripple of the switch can be absorbed, and the parallel output capacitor... C 2. The small capacitance value can improve the network's filtering effect on higher frequency ripples.

[0024] In this embodiment, port p The voltage of 1 is denoted as ,port p The voltage of 2 is denoted as ,capacitance C The capacitance value of 1 is denoted as ,capacitance C The capacitance value of 2 is denoted as winding L 1 and L 2 Self-induction and mutual induction The same sensitivity is denoted as winding L The self-perception of 3 is recorded as winding L 3 relative to L 1. L The mutual inductance of 2 is and Mutual inductance is denoted as Coupling coefficient Defined as: (1) According to Kirchhoff's voltage loop and current node laws, we can obtain Figure 2 The voltage loop and current node equations for the circuit shown are as follows: (2) Coupled winding L 1 and L The current in 2 is equal to the input current. Equation (2) can be simplified to the following equation: (3) Filter capacitor C 1. Absorption comes from inductance L The ripple current of 3 has a small voltage fluctuation across its terminals, and the inductor... L The voltage across the capacitor needs to maintain volt-second balance within one switching ripple cycle. Therefore, the capacitor can be approximated as... C voltage of 1 According to equation (3), the coupling winding can be obtained. L 1. L 2. L The differential equations for the current and the input and output currents of component 3 are as follows: (4) From equation (4), it can be seen that by reducing the input current ripple and inductance... L When the current ripple amplitudes of 3 are equal but their directions are opposite, the port can be eliminated. p 2 high-frequency ripple current, i.e. (5) According to equations (4) and (5), the coupling winding can be obtained. L 3's self-perception and L 3 Relative to winding L 1. L Mutual intuition of 2 satisfies: (6) When the coupling winding L 3's self-perception and L 3 Relative to winding L 1. L When the mutual inductance of 2 satisfies the constraint condition of equation (6), high-frequency ripple suppression can be achieved. C When the capacitance value of 2 is very small, the key waveform of the ripple cancellation network is as follows: Figure 3 As shown.

[0025] In this embodiment, the proposed ripple cancellation network p 2 is used as the output port, and the resistance value is denoted as . load R At that time, the equivalent network after decoupling is as follows: Figure 4 As shown, the port can be obtained. p 2 pairs of ports p The transfer function of 1 is: (7) As can be seen from equation (7), there exists a critical mutual inductance coefficient. : (8) According to the numerator of equation (7), L 3 and C 1 forms a series resonant notch network, when At the notch frequency With a gain close to zero, designing the notch filter frequency at the switching frequency can effectively eliminate the sub-high frequency ripple of the switching circuit. The notch filter frequency... for: (9) According to equation (7), , , , For example, the output capacitor is obtained. C2. Gain transfer function under different capacitance values The amplitude-frequency curve is as follows Figure 5 As shown. From Figure 5 It can be seen that when the output capacitor C A larger capacitance value (1mF) results in better high-frequency attenuation characteristics, but it also introduces an additional resonant peak near the switching frequency. This effect varies with the output capacitance. C As the capacitance value gradually decreases (1mF→0.1mF→0.01mF), the frequency at the resonant peak gradually increases and moves further away from the notch filter frequency. Considering the system's size, stability, and high-frequency attenuation characteristics, the output capacitor can be... C 2. Ripple capacitors with a capacitance value less than 10 times the rated value C A tolerance value of 1.

[0026] To achieve precise control of the self-inductance and mutual inductance of coupled inductors in a ripple cancellation network, this invention proposes an optimized design method for cross-winding of windings based on a dual magnetic ring. The winding method is as follows: Figure 6 As shown, two identical magnetic rings A and B are stacked, and the windings... L 1. L 2 and L 3. Three strands are wound together on two stacked magnetic rings to form a winding. Turns, then winding L 1 and L 2. Two additional strands are wound in parallel on magnetic ring A. Turns, windings L 3. Additional winding on magnetic ring B Since there is a gap between the two stacked magnetic rings, the magnetic circuits of the two magnetic rings can be considered to be independent of each other, that is, the magnetic flux is mainly distributed in their respective magnetic rings.

[0027] For windings L For example, the number of turns of magnetic ring A is ( ). The number of turns on magnetic ring B is For the winding L For example, the number of turns of magnetic ring A is ( ). The number of turns on magnetic ring B is For the winding L For 3, the number of turns on magnetic ring A is The number of turns on magnetic ring B is .

[0028] The magnetic reluctance of magnetic ring A and magnetic ring B is (Magnetic reluctance of a single magnetic ring), the total magnetic reluctance after stacking is Assuming the current flows through the winding L 1. L 2 and L The currents of 3 are respectively I 1. I2 and I 3. Then the magnetomotive forces on magnetic ring A and magnetic ring B can be obtained respectively as follows: (10) According to equation (10), the magnetic flux on magnetic ring A and magnetic ring B can be obtained as follows: (11) L 1's self-perception is when I 2= I When 3=0, L 1 magnetic flux and I The ratio of 1, L The flux linkage of 1 is: (12) but L 1's self-perception for: (13) Due to inductance coefficient ,therefore L The intuition of 1 can be expressed as: (14) Similarly, we can obtain L 2 and L 3 self-perception , for: (15) Due to the winding L 1 and L 2. Always wound in pairs around the same magnetic ring. L 1 and L The self-inductance of 2 is equal to its mutual inductance, that is: (16) winding L 1 relative to the winding L Mutual inductance of 3 When I 2= I When 3=0, I 1 in L Magnetic linkage in 3 and I The ratio of 1, I 1 in L The magnetic flux linkage in 3 is: (17) Then the winding L 1 relative to the winding L Mutual inductance of 3 for: (18) Due to the winding L 1 and winding L 2. Always two strands wound in parallel, winding L 2 Relative to winding L Mutual inductance of 3 .

[0029] Based on equations (14), (15), and (18), the winding can be obtained. L 1 and L 2 Relative to winding L The expression for the mutual inductance coefficient of 3 is as follows: (19) Winding L 1 and winding L The self-inductance of 2 is winding L The self-inductance of 3 is According to equations (14), (15) and (18), equation (19) can be transformed into: (20) Number of turns and It can be represented as: (twenty one) According to equations (20) and (21), it can be seen that, given the self-inductance... and Below, the number of turns can be changed. To achieve mutual inductance coefficient Adjustment, and simultaneously adjust the number of turns. and To ensure self-sensitivity and constant.

[0030] In this embodiment, given , , The mutual inductance coefficient can be obtained. , and Follow The changing curve is as follows Figure 7 As shown. From Figure 7 It can be seen from this that the mutual inductance coefficient along with The number of turns increases with the increase of [something]. and along with The number of turns decreases as the number of turns increases. Furthermore, the number of turns calculated according to equation (21) and The number of turns in a winding cannot be non-integer; therefore, the calculated number of turns must be considered. The value is rounded down.

[0031] when When the number of turns changes, it is based on the rounded-down number of turns. and The calculated winding self-inductance and mutual inductance coefficients are as follows: Figure 8 As shown, from Figure 8 It can be seen that the number of turns after rounding and The effect on the winding self-inductance and mutual inductance coefficients is negligible.

[0032] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be easily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and shown herein.

Claims

1. A full-bridge inverter output ripple cancellation network, characterized in that, Includes a full-bridge circuit, wherein the full-bridge circuit is electrically connected to the first upper port ( p 11 ) and the first lower port ( p 12 ); First upper port ( p 11 ) and the first lower port ( p 12 ) Electrically connected coupling inductor; the coupling inductor includes a first coupling winding ( L 1 ), second coupling winding ( L 2 ) and the third coupling winding ( L 3 ); where the first coupling winding ( L 2 ) and second coupling winding ( L 2 The coupling coefficient of the third coupling winding is 1; L 3 ) self-perception as The third coupling winding ( L 3 ) and the first coupling winding ( L 1 ) and second coupling winding ( L 2 The mutual inductance of ) are all ,but and satisfy: ； Among them, the first upper port ( p 11 Electrical connection to the first coupling winding ( L 1 The same-named end of the first coupling winding () L 1 The third coupling winding is electrically connected to the opposite-named terminal. L 3 The opposite terminal of the output capacitor () C 2) One end and the second upper port ( p 21 ); First lower port ( p 12 Electrical connection to the second coupling winding ( L 2 The opposite end of the second coupling winding () L 2 The same terminal of the ripple capacitor is connected to the same terminal. C 1) One end, output capacitor ( C 2) The other end and the second lower port ( p 22 ); third coupling winding ( L 3 The same terminal of the ripple capacitor is connected to the same terminal. C The other end of 1).

2. The full-bridge inverter output ripple cancellation network as described in claim 1, characterized in that, The third coupling winding ( L 3 ) and the first coupling winding ( L 1 ) and the second coupling winding ( L 2 Coupling coefficient for: ； For the first coupling winding ( L 2 ) and the second coupling winding ( L 2 (self-perception); Critical mutual inductance coefficient for: ； in, .

3. The full-bridge inverter output ripple cancellation network as described in claim 2, characterized in that, The third coupling winding ( L 3 ) and ripple capacitor ( C 1) Series resonance forms a notch filter network, and the notch frequency of the notch filter network... for: ； in, For ripple capacitor ( C 1) The capacitance value.

4. The full-bridge inverter output ripple cancellation network as described in claim 1, characterized in that, The output capacitor ( C 2) Capacity is Ripple capacitor ( C 1) Capacity ,but .

5. The full-bridge inverter output ripple cancellation network as described in claim 1, characterized in that, The full-bridge circuit includes a first switching transistor ( ), second switching transistor ( ), third switching transistor ( ) and the fourth switch ( ); where the first switching transistor ( The source of the second switching transistor is electrically connected to the source of the transistor. The drain and the first upper port () ); First switching transistor ( The drain of the third switching transistor is electrically connected to the third switching transistor. The drain of the third switching transistor () The source of the transistor is electrically connected to the fourth switching transistor. The drain and the first lower port () ); Fourth switching transistor ( The source of the second switching transistor is electrically connected to the source of the transistor. The source pole of ).

6. The full-bridge inverter output ripple cancellation network as described in claim 4, characterized in that, The first switching transistor ( ), second switching transistor ( ), third switching transistor ( ) and the fourth switch ( All of them are MOSFETs.

7. A method for designing coupled inductors, characterized in that, The coupled inductor, as described in any one of claims 1-6, includes the following steps: Step 1: Stack identical magnetic rings A (1) and B (2) to form a stacked structure; Step 2, First coupling winding ( L 1 ), second coupling winding ( L 2 ) and the third coupling winding ( L 3 Three strands are wound together on a stacked structure to form... Turns; Step 3, First coupling winding ( L 1 ) and second coupling winding ( L 2 Two additional strands are wound around the magnetic ring A(1). Turns, third coupling winding ( L 3 Additional windings are made on magnetic ring B(2). Turns; Step 4: Change the number of turns To adjust the coupling coefficient , making .

8. The coupled inductor design method as described in claim 7, characterized in that, Changing the number of turns At that time, by adjusting the number of turns This makes the first coupling winding ( L 1 ) and second coupling winding ( L 2 Each person's self-perceived sense Keep it unchanged, adjust the number of turns To ensure the third coupling winding ( L 3 ) self-sensitivity constant.

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