LLC resonant power converter with printed circuit board winding

Abstract

The application discloses an LLC resonant power converter with printed circuit board winding, comprising: a switching circuit electrically coupled to an input DC voltage, converting the DC voltage into a switching signal; a resonant tank electrically coupled to the switching circuit, receiving the switching signal to provide a primary side current; a transformer circuit electrically coupled to the resonant tank, comprising a plurality of discrete transformers, each transformer having a primary and secondary winding disposed on a printed circuit board, the primary winding of each transformer can be selectively connected in series or parallel with the primary winding of other transformers to form a dynamically changing equivalent primary winding, and the turns ratio is maintained to allow the resonant tank to be finely tuned accordingly. The resonant tank dynamically adjusts the gain curve by electrically coupling external excitation inductance, resonant capacitance or resonant inductance according to the output current requirement of the LLC resonant power converter.

Description

Technical Field

[0001] This invention relates to the field of LLC resonant power converters, and more specifically to an LLC resonant power converter with printed circuit board windings. Background Technology

[0002] In traditional switched power supplies, magnetic components are typically used for filtering, energy storage, and transmission. The higher the operating frequency of the switching component, the smaller the size of the magnetic component can be, making it easier to achieve miniaturization, weight reduction, and cost reduction of the power supply. However, increasing the switching frequency also increases the switching losses of the switching component, hence the development of soft-switching technology. To achieve ideal soft switching, the best scenario is to make the switch (switching component) turn off and on when both voltage and current are zero (zero-voltage switching, ZVS; zero-current switching, ZCS), thus truly eliminating losses. To achieve this goal, resonant technology must be employed.

[0003] According to circuit principles, an inductor and capacitor connected in series or in parallel can form a resonant circuit, causing the current in the circuit to change sinusoidally when the power supply is DC. Since the current or voltage changes sinusoidally, there is a zero-crossing point. If the switching component is turned on or off at this point, the resulting loss is zero.

[0004] An LLC resonant power converter is a resonant inverter with three reactive elements. The DC input voltage is converted to a square wave via a switch network configured as a half-bridge or full-bridge to feed into the LLC resonant tank, effectively filtering harmonics and providing a sinusoidal voltage and current waveform. This, in turn, powers a transformer that provides voltage scaling and primary-secondary isolation. The converter's power flow is controlled by modulating the square wave frequency relative to the resonant tank circuit. In an LLC resonant power converter, all semiconductor switches are soft-switching or zero-voltage switching (ZVS) when the primary MOSFETs are on, and the secondary rectifiers are zero-current switching (ZCS) when on and off, resulting in low electromagnetic emission levels. Furthermore, it enables a high degree of integration of magnetic components, thereby allowing the design of converters with higher efficiency and power density.

[0005] An LLC resonant power converter is a topology of a series resonant converter that provides an output voltage signal isolated from the input signal. An LLC resonant power converter includes a series resonant circuit with a transformer primary winding. A switching circuit alternately couples the switching node of the resonant circuit or energy storage circuit to a positive power node and a ground node to provide an AC resonant current flowing through the transformer primary winding. Secondary circuitry (e.g., a rectifier) ​​provides the output voltage to drive the load. This secondary circuitry may include a synchronous rectifier switch or a diode rectifier. The primary-side switching circuitry can be regulated to regulate the output voltage. LLC resonant power converters offer high efficiency and high power density, and can provide zero-voltage switching and low shutdown current for the primary-side switching over a fairly wide load range. These advantages make LLC resonant power converters suitable for a variety of applications, such as high-performance servers and telecommunications applications.

[0006] As mentioned earlier, when the primary-side switching frequency is below the resonant frequency, the primary-side switch can be turned off with zero-current switching. This helps improve voltage gain capability without reducing efficiency in applications with hold-up time requirements. Operating at high switching frequencies can reduce the size of magnetic components and capacitors in LLC resonant power converters. However, this increases switching-related losses and magnetic component losses, leading to inefficiency. Due to core and winding losses, especially at high switching frequencies, the magnetic components used in LLC resonant power converters remain a limitation to improving converter efficiency. Further improvements are needed to support higher efficiency and power density in LLC resonant power converters.

[0007] Traditional LLC resonant power converters have large magnetic components, and the size of the core and windings cannot be reduced due to power and operating frequency limitations. LLC resonant power converters cannot change the parameters of the resonant tank. When the output voltage or current requirement exceeds the design of the resonant tank, the power converter cannot operate. How to efficiently improve power density and widen the output voltage and current range of LLC resonant power converters are problems that need to be addressed in the development of LLC resonant power converters.

[0008] Therefore, there is an urgent need to improve the shortcomings of existing LLC resonant power converters by introducing flux cancellation technology to reduce the size of magnetic components, fabricating transformer windings on printed circuit boards, reducing stray characteristics of magnetic components, changing resonant slot parameters to obtain a larger output voltage and current range, and improving the power density of the power converter. Summary of the Invention

[0009] Based on the above, this invention proposes an LLC resonant power converter with printed circuit board windings, comprising: a switching circuit electrically coupled to an input DC voltage to convert the DC voltage into a switching signal; a resonant slot electrically coupled to the switching circuit, the resonant slot being composed of a resonant inductor, a magnetizing inductor, and a resonant capacitor, used to receive the switching signal to provide primary side current; a transformer circuit electrically coupled to the resonant slot, the transformer circuit comprising multiple discrete transformers, each transformer having a primary side winding and a secondary side winding, wherein the primary side winding and the secondary side winding are disposed on a printed circuit board to effectively reduce stray characteristics caused by winding; wherein the printed circuit board comprises multiple vias, a multilayer board, and multiple windings, wherein the positions of the multiple vias correspond to the magnetic cores of the multiple discrete transformers, used to allow the magnetic cores of the multiple discrete transformers to pass through the corresponding multiple vias; multiple windings disposed on each layer of the multilayer board, each surrounding the magnetic cores of the multiple discrete transformers to generate induced electromotive force; multiple windings disposed on each layer of the multilayer board... The multiple windings on the layer are the aforementioned primary or secondary windings; wherein, the primary winding of an individual transformer can be dynamically selected to be electrically coupled or isolated from the resonant slot, and can be dynamically selected to be connected in series or in parallel with the primary windings of other transformers to form a dynamically changing equivalent primary winding, and the resonant slot electrically coupled to the transformer circuit can be finely adjusted accordingly while maintaining the turns ratio; and a rectifier filter circuit coupled to the transformer circuit is used to rectify and filter the secondary current output from the secondary winding of the transformer circuit to provide an output voltage; wherein, one end of the resonant inductor is electrically coupled to the switching circuit, and the other end is connected in series with the equivalent primary winding; the magnetizing inductor is connected in series with the resonant inductor, and one end of the resonant capacitor is connected in series with the magnetizing inductor, and the other end is electrically coupled to the switching circuit; the magnetizing inductor is connected in parallel with the equivalent primary winding; wherein, the resonant slot dynamically adjusts the gain curve of the LLC resonant power converter according to the output current requirements of the LLC resonant power converter by electrically coupling to an external magnetizing inductor, an external resonant inductor, or an external capacitor.

[0010] In one embodiment, the external magnetizing inductor, external resonant inductor, or external capacitor that form the dynamically changing equivalent primary winding and electrically coupled resonant slot are dynamically adjusted by a combination of multiple switches.

[0011] In one embodiment, the aforementioned multiple switches are various types of switches such as transistor switching assemblies and relays.

[0012] In one embodiment, the external magnetizing inductor is either the leakage inductance of the transformer itself or an external inductance. The inductance value in the resonant slot is adjusted by changing the windings of the magnetic components in the resonant slot through the multiple switches, or by connecting external magnetic components in series or parallel.

[0013] In one embodiment, the aforementioned external magnetizing inductor is used to dynamically adjust one of the resonant slot parameters K, i.e., the inductance ratio, so that the gain curve of the LLC resonant power converter is dynamically adjusted accordingly to meet the demand of its output current Io.

[0014] In one embodiment, the external resonant capacitor is either a stray capacitor or an external capacitor. The capacitance value in the resonant slot is changed by adjusting the series and parallel connection of the capacitors through the multiple switches.

[0015] In one embodiment, the aforementioned external resonant capacitor is used to adjust the quality factor Q while keeping the inductance ratio K constant, so that the gain curve of the LLC resonant power converter is dynamically adjusted accordingly to meet the demand of its output current Io.

[0016] In one embodiment, the aforementioned external resonant inductor is either the transformer's own inductance or an externally applied inductor. The inductance value within the resonant slot is adjusted by changing the windings within the magnetic components of the resonant slot through the aforementioned multiple switches, or by using externally applied magnetic components in series and parallel.

[0017] In one embodiment, the aforementioned external resonant inductor is used to adjust the quality factor Q and the inductance ratio K, so that the gain curve of the LLC resonant power converter is dynamically adjusted accordingly to meet the demand for output current Io.

[0018] In one embodiment, the aforementioned multiple switch configuration, through an external controller electrically coupled to the LLC resonant power converter, outputs corresponding resonant tank adjustment signals to the resonant tank and transformer respectively based on the output voltage feedback and output current feedback received by the external controller, so as to achieve the purpose of adjusting the range of output voltage and output current of the LLC resonant power converter. Attached Figure Description

[0019] The components, features, and advantages of the present invention can be understood through the detailed description of the preferred embodiments outlined in the specification and the accompanying drawings:

[0020] Figure 1 This diagram shows a schematic of the circuit architecture of an LLC resonant power converter in the prior art.

[0021] Figure 2(A) shows a circuit diagram of an LLC resonant power converter with a printed circuit board transformer winding according to an embodiment of the present invention.

[0022] Figure 2(B) shows a plan view of a printed circuit board transformer winding in an LLC resonant power converter according to an embodiment of the present invention.

[0023] Figure 2(C) shows a circuit diagram of the resonant slot design in a resonant power converter with a printed circuit board winding LLC according to an embodiment of the present invention.

[0024] Figure 2(D) shows a schematic diagram of the circuit architecture of a resonant power converter with a printed circuit board winding LLC according to an embodiment of the present invention.

[0025] Figure 3(A) shows a schematic diagram of a resonant groove design proposed according to an embodiment of the present invention.

[0026] Figure 3(B) shows a comparison of the gain curves between the resonant slot design proposed according to an embodiment of the present invention based on Figure 3(A) and the initial resonant slot design.

[0027] Figure 4(A) shows a schematic diagram of a resonant groove design proposed according to another embodiment of the present invention.

[0028] Figure 4(B) shows a comparison of the gain curves between the resonant groove design proposed according to an embodiment of the present invention based on Figure 4(A) and the initial resonant groove design.

[0029] Figure 5(A) shows a schematic diagram of a resonant groove design proposed according to another embodiment of the present invention.

[0030] Figure 5(B) shows a comparison of the gain curves between the resonant slot design proposed according to an embodiment of the present invention based on Figure 5(A) and the initial resonant slot design.

[0031] Figure 6 This diagram shows a circuit block diagram and related operation control flow of an LLC resonant power converter according to an embodiment of the present invention.

[0032] Explanation of key component symbols:

[0033] Half-bridge switching circuit 101

[0034] Resonant slot 103

[0035] Transformer 104

[0036] 105 Rectifier and filter circuit

[0037] Planar transformer winding structure 20

[0038] Magnetic cores 21, 22, 23 and 24

[0039] Through holes 27-1, 27-2, 27-3 and 27-4

[0040] Full-bridge switching circuit 201

[0041] Resonant slot 203

[0042] Transformer circuit 204

[0043] Circuit block 203-1

[0044] 205 Rectifier and filter circuit

[0045] Resonant slot 303

[0046] Transformer Circuit 304

[0047] Circuit block 303-1

[0048] Curves 311, 313, 321 and 323

[0049] Resonant slot 403

[0050] Transformer circuit 404

[0051] Circuit block 403-1

[0052] Curves 411, 413, 421 and 423

[0053] Resonant slot 503

[0054] Transformer Circuit 504

[0055] Circuit block 503-1

[0056] Curves 511, 513, 521 and 523

[0057] 601 Full-bridge / Half-bridge Switching Circuit

[0058] 603 Resonant Slot and Transformer Circuit

[0059] 605 rectifier filter circuit

[0060] External control circuit 607 Detailed Implementation

[0061] Some preferred embodiments of the invention will now be described in more detail. However, it should be understood that the preferred embodiments of the invention are provided for illustrative purposes and not for limiting the invention. Furthermore, the invention may be practiced in a wide range of other embodiments besides those explicitly described, and the scope of the invention is not expressly limited unless specified in the appended claims.

[0062] As previously described in the background section, the magnetic components of LLC resonant power converters are large, and the size of the core and windings cannot be reduced due to power and operating frequency limitations. LLC resonant power converters cannot change the parameters of the resonant tank. When the output voltage or current requirements exceed the resonant tank design, the power converter cannot operate. How to efficiently improve power density and widen the output voltage and current range of LLC resonant power converters are problems that need to be addressed in the development of LLC resonant power converters.

[0063] Figure 1 This is a schematic diagram of the circuit architecture of an existing LLC resonant power converter 100, a full-bridge LLC resonant power converter with an array transformer core integrated with synchronous rectification. The LLC resonant power converter is used to convert the DC input voltage V... in Converted to DC output voltage V o To provide load R L The system includes a half-bridge switching circuit 101, a resonant tank 103, a transformer 104, and a rectifier-filter circuit 105. The switching circuit 101 is used to control the DC voltage V. in The input. The resonant slot 103 is coupled to the switching circuit 101, which includes a resonant inductor L connected in series. r Magnetizing inductance L m and resonant capacitor C r The transformer 104 is coupled to the resonant slot 103 and includes a magnetic core, a primary (main and secondary) winding, and a secondary winding. The secondary winding is rectified by a center tap and rectified by a rectifier switch.

[0064] During the operation of the LLC resonant power converter 100, the output / input nodes of the half-bridge switching circuit 101 are alternately turned on due to the periodic switching of the switching switch, generating a periodically changing switching signal. When the signal is input to the resonant slot 103, the magnetizing inductor L... m The voltage and back electromotive force are repeatedly generated by the excitation, due to the resonant inductance L of the primary winding of transformer 104 and resonant slot 103. r and resonant capacitor C r Series connection with magnetizing inductor L m The parallel connection creates a primary current in the circuit that varies sinusoidally, while the secondary winding of transformer 104 continuously generates a periodically changing current. This current is rectified and filtered by rectifier and filter circuit 105, converting it into a DC current output to provide a DC output voltage V. o Give load R L Basically, once the circuit topology of an LLC resonant power converter is determined, its resonant tank parameters are fixed and cannot be adjusted for different operating conditions. That is, the range of its output voltage and output current cannot be adjusted according to operational needs.

[0065] To improve the power density and increase the output voltage and current range of LLC power converters, this invention proposes to reduce the size of magnetic components by introducing flux cancellation technology, fabricating transformer windings on a printed circuit board to reduce stray characteristics of magnetic components, and changing the resonant slot parameters to obtain a larger output voltage and current range, thereby increasing the power density of the power converter and addressing the shortcomings of existing LLC power converters.

[0066] The technical means proposed in this invention is to design the winding on the printed circuit board to reduce the influence of stray characteristics caused by the winding, and realize the component as shown in Figure 2(A), an array transformer (a collection of multiple transformers).

[0067] Figure 2(A) shows a schematic diagram of the component circuit in the LLC resonant power converter of the present invention, in which the transformer windings are arranged on a printed circuit board. In the embodiment shown in the figure, there are four sets of transformers (T1, T2, T3, T4), discrete transformers that can be arranged in an array. Since the transformer windings are designed on the printed circuit board, the secondary windings in Figure 2(A) are all set to 1 turn, and the primary windings of transformers T1-T4 are all designed to have N / 2 turns. If the primary windings of transformers T1 and T2 are connected in series, the number of turns of each individual primary winding is N... p1 =N / 2 and N p2 = N / 2, the combined number of turns in the primary winding is N turns, and the turns ratio of the transformer is N:1; if the primary windings of transformers T1 and T3 are connected in series, the turns ratio is also N:1, but its L r With L m The stray capacitance differs from that of the primary windings of T1 and T2 connected in series; if the primary windings of transformers T1 and T4 are connected in series, the turns ratio remains N:1, but L r With L m The stray capacitance also differs from the series connection method described above. Even if the primary windings of two different transformer sets are connected in series to maintain the same turns ratio, the relative positions and distances between the windings will change depending on the series connection configuration, leading to variations in the resonant slot parameter L. r With L m And stray capacitance will change accordingly.

[0068] In one embodiment, the planar transformer winding structure 20 on the PCB includes a multilayer board (e.g., a four- or eight- or more-layer PCB board), as shown in FIG2(B). Multiple through-holes (27-1, 27-2, 27-3, and 27-4) are formed on the multiple PCB layers to allow the magnetic cores 21, 22, 23, and 24 corresponding to the array transformers T1, T2, T3, and T4 to pass through, so that the windings formed on each layer of the PCB (including primary and secondary windings) can surround the magnetic cores 21, 22, 23, and 24 to generate an induced electromotive force. The multiple wirings of the secondary winding fabricated on the first layer (Layer 1), namely Ns1-1, Ns1-2, Ns1-3, and Ns1-4, surround the magnetic cores 21, 22, 23, and 24 respectively. 2) The primary windings of the first-side windings are Np1-1, Np1-2, Np1-3 and Np1-4 (not shown) which are respectively wrapped around the magnetic cores 21, 22, 23 and 24; the primary windings of the third layer are Np2-1, Np2-2, Np2-3 and Np2-4 (not shown) which are respectively wrapped around the magnetic cores 21, 22, 23 and 24; the secondary windings of the fourth layer are Ns2-1, Ns2-2, Ns2-3 and Ns2-4 which are respectively wrapped around the magnetic cores 21, 22, 23 and 24.

[0069] In one embodiment, the array transformer, as described above, generally uses a four-layer PCB board to fabricate the wiring of its windings; wherein, the wiring of the primary winding is fabricated on the second layer (Layer 2) and the third layer (Layer 3), and the wiring of the secondary winding is fabricated on the first layer (Layer 1) and the fourth layer (Layer 4).

[0070] The examples above only illustrate the wiring of transformer windings made on four-layer PCBs. Similar concepts can be extended to the wiring of transformer windings made on eight-layer, sixteen-layer, or more PCBs.

[0071] Therefore, by changing the series and parallel connection of the windings, even if the turns ratio remains unchanged, the resonant slot parameter L can still be slightly adjusted due to the change in the routing of the windings between different layers. r With L m And stray capacitance.

[0072] According to the spirit of the present invention, the transformer winding shown in Figure 2(A) above is only an example, wherein the winding configuration of the discrete array transformer can vary, and is not limited to 4 sets of primary side coils to 4 sets of secondary side coils, but can also be 4 sets of primary side coils to 1 set of secondary side coils, or 4 sets of primary side coils to 6 sets of secondary side coils.

[0073] The voltage gain of the LLC resonant power converter is expressed by equation (1), if L r L m C r If both I and N are fixed values, then the gain value is determined by the output current I. o Output voltage V o and operating frequency f s Decision, when I o V o To achieve the target value, change f s Obtain the desired gain value.

[0074]

[0075] Where K = L r / L m (Inductance ratio); (Quality Factor); (Resonant frequency); N is the turns ratio of the transformer.

[0076] This invention allows for four methods of changing the resonant groove, namely (i) adjusting the external L m (ii) Adjust external C r (iii) Adjust external L r and (iv) adjust the series and parallel connection method of the transformer windings to change L m With L r .

[0077] Figure 2(C) shows the circuit block 203-1 of the resonant slot 203 coupled to the transformer circuit 204 in the LLC resonant power converter with printed circuit board windings proposed according to the present invention. According to the above design concept, as shown in Figure 2(C), after selecting the winding arrangement of the transformer circuit on the printed circuit board, multiple switches S1, S2, S3... can be used to externally connect L in series and parallel. m1 L r1 and C r1 To adjust the resonant slot; circuit block 203-1 only shows the external L connected in parallel. m1 L r1 and C r1 This is merely an example; other external connection methods are also included in the concept of this invention. The transformer circuit 204 includes four discrete transformers T1, T2, T3, and T4.

[0078] Figure 2(D) shows a schematic diagram of the circuit architecture of an LLC resonant power converter according to one embodiment of the present invention. As shown in Figure 2(D), the primary windings of transformers T1 and T2 are connected in series, and the number of turns of each primary winding is N. p1 =N / 2 and N p2= N / 2, the combined number of turns in the primary winding is N turns, and the transformer turns ratio is N:1, which is only used as an example for illustration; as explained in the previous section, even if the turns ratio remains unchanged, the resonant slot parameter L r With L m And stray capacitance can still be adjusted by the electrical connection method between different transformers.

[0079] Figure 2(D) illustrates the operation of the LLC resonant power converter of the present invention with the primary windings of transformers T1 and T2 connected in series as an example, using this transformer circuit configuration. As shown in Figure 2(D), the LLC resonant power converter of the present invention converts the input voltage V... in Converted to output voltage V o The system, designed to supply power to the load, includes a full-bridge switching circuit 201, a resonant tank 203, transformers (T1, T2, T3, T4), a rectifier and filter circuit 205, and a control circuit (not shown). Figure 2(D) shows a full-bridge switching circuit as an example, but it is not limited to this and may also include a half-bridge switching circuit. The rectifier and filter circuit 205 has a rectifier and filter circuit 205 connected to the transformers (T1, T2, T3, T4) (containing multiple sets of center-tapped secondary windings, each center-tapped secondary winding including positive and negative half-cycle windings, each positive and negative half-cycle winding connected in series with a rectifier switch and a capacitor for rectification and filtering of the positive and negative half-cycles). The full-bridge switching circuit 201 includes switching switches Q1, Q2, Q3, and Q4, wherein, in the positive half-cycle operation mode, the primary side upper bridge switch Q1 and the primary side lower bridge switch Q4 are turned on, and the primary side upper bridge switch Q3 and the primary side lower bridge switch Q2 are turned off, and current flows through L. r The primary windings of transformers T1 and T2, and L connected in parallel with the primary windings of transformers T1 and T2. m And C r The upper half-cycle of the secondary winding coupled to each other is rectified and filtered to generate the output voltage V. o To provide load R L In the negative half-cycle operation mode, primary side upper bridge switch Q3 and primary side lower bridge switch Q2 are turned on, while primary side upper bridge switch Q1 and primary side lower bridge switch Q4 are turned off, and current flows through L. r The primary windings of transformers T1 and T2, and L connected in parallel with the primary windings of transformers T1 and T2. m And C r The lower half-cycle windings of the respective coupled secondary windings are rectified and filtered to generate the output voltage V. o To provide load R L use.

[0080] The circuit block 203-1 of the resonant slot 203 coupled to the transformer circuit 204 in Figure 2(C) can have different variations. The impact of the variations in circuit block 203-1 on the voltage gain of the LLC resonant power converter will be discussed in subsequent paragraphs. See Figure 3-5 and its corresponding description for details.

[0081] Figure 3(A) shows a circuit block 303-1 of an LLC resonant power converter with printed circuit board windings according to one embodiment of the present invention, in which the resonant slot 303 is coupled to the transformer circuit 304. According to the above design concept, after the selected primary windings of the transformers are connected in series (for example, the primary windings of transformers T1 and T2 are connected in series, and transformers T3 and T4 are disconnected), when the resonant slot parameters are fixed, i.e., the initial state in the figure (left view of Figure 3(A)), the initial state is that switches S1, S2 and S3 are all not conducting. o V o Changing the Q value will change the Q value; the gain curve M(f) can be plotted based on the change in Q value. s (K,Q) and operating frequency f s The relationship diagram is shown in Figure 3(B). If I o As demand increases, the Q value changes from Q1 to Q2, and the gain value changes from over 1.5 to under 1.5 (from curve 311 to curve 313), causing the power converter to malfunction. If adjusting the external L... m To change the resonant slot, i.e., to turn on the switch S2 (right side of Figure 3(A)), compared to the initial state, the L of the resonant slot... m The value changes from a fixed value to L m '(i.e. L) m / / L m1 It includes an initial fixed magnetizing inductance L. m Electrically coupled first inductor L m1 By turning on switch S2, under the changed K1 parameter (from K to K1), if I o As the demand increases, the corresponding Q1 and Q2 gain curves 321 change to curve 323. Under parameter K1, the Q2 gain value is greater than 1.5, which can meet the gain requirement.

[0082] The examples given above are merely illustrative of how to adjust the external L m To adjust the resonant slot parameters, L m With L m1 Depending on the application, such as different layers of printed circuit boards, the electrical coupling between them can be selected in series or parallel.

[0083] In one embodiment, the above-mentioned electrically coupled first inductor L m1The inductance can be the transformer's own inductance, leakage inductance, or an external inductance. The inductance value within the resonant slot can be adjusted by connecting switches, relays, or any other type of switch in series or parallel, along with external magnetic components. This dynamically adjusts the resonant parameter K, i.e., the inductance ratio, thereby changing the gain curve M(f). s (,K,Q) can follow I o The demand was adjusted accordingly.

[0084] Figure 4(A) shows the circuit block 403-1 of the LLC resonant power converter with printed circuit board windings proposed according to one embodiment of the present invention, in which the resonant slot 403 is coupled to the transformer circuit 404. After being connected in series with the selected primary winding of the transformer (same as in Figure 3), the circuit is adjusted by external C. r To change the resonant tank. When the resonant tank parameters are fixed, i.e., the initial state in the diagram (left side of Figure 4(A)), switches S1, S2, and S3 are all off, I o V o Changing the Q value will change the Q value; the gain curve M(f) can be plotted based on the change in Q value. s (K,Q) and operating frequency f s The relationship diagram is shown in Figure 4(B). If I o As demand increases, the Q value changes from Qa to Qb, and the gain value changes from more than 1.5 to less than 1.5 (from curve 411 to curve 413), causing the power converter to malfunction. If the state of switch S3 is changed to on (i.e., the right side of Figure 4(A)), then the C of the resonant tank... r The value is changed to C r =C r +C r1 (Variable resonant capacitor), which includes an initial fixed capacitance C r Electrically coupled first capacitor C r1 Compared to the initial state, the change of switch S3 to conduction causes a change in the Q value, but the K value remains the same. The gain curve M(f) can be plotted. s (K,Q) and operating frequency f s The relationship diagram is shown in Figure 4(B). If I o With increased demand, under the same K parameters, the Q value changes from Qc to Qd, and the corresponding gain curves are curves 421 and 423. The Qd gain value under the K parameters is greater than 1.5, which can meet the gain requirement.

[0085] The examples given above are for illustrative purposes only. r With C r1 There are many different combinations of electrical coupling between them. Depending on the application, series or parallel electrical coupling is selected. They are not listed here. The above is only for illustrative purposes and is not intended to limit the scope of the claims of this invention.

[0086] In one embodiment, the first resonant capacitor C is described above. r1 It can be a stray capacitor in the circuit or an external capacitor. The capacitance value in the resonant slot can be changed by adjusting the series and parallel connection of the capacitor through any form of switch assembly, relay, etc.

[0087] In one embodiment, the above-mentioned method of changing the capacitance value in the resonant slot by adjusting the series and parallel connection of capacitors can be achieved by configuring multiple switches between different capacitors.

[0088] Figure 5(A) shows the circuit block 503-1 of the LLC resonant power converter with printed circuit board windings proposed in one embodiment of the present invention. The resonant slot 503 is coupled to the transformer circuit 504. After being connected in series with the selected primary winding of the transformer (same as in Figure 3), the circuit is adjusted by external L... r To change the resonant slot. The initial state is that switches S1, S2, and S3 are all off (i.e., the left side of Figure 5(A)). If I... o As demand increases, the Q value changes from Q1 to Q2, and the gain value changes from more than 1.5 to less than 1.5 (from curve 511 to curve 513), as shown in Figure 5(B). The power converter cannot operate at the required gain value. If switch S1 is turned on (i.e., the right side of Figure 5(A)), the L of the resonant tank can be increased. r Adjust to L r '=L r / / L r1 (Variable resonant inductor), which includes an initial fixed resonant inductance L r Electrically coupled second inductor L r1 Compared to the initial state, the switch S1 changes to be on, causing changes in both the K and Q values. The gain curve M(f) can be plotted as follows. s (K,Q) and operating frequency f s A relationship diagram, where the value of K changes from K to K2, if I o As demand increases, the Q value changes from Q3 to Q4. The corresponding gain curves are curve 521 and curve 523. It can be seen that the gain value of Q4 under the K2 parameter is greater than 1.5, which can meet the gain requirement.

[0089] The examples given above are for illustrative purposes only. r With L r1 There are many different combinations of electrical coupling between them. Depending on the application, series or parallel electrical coupling is selected. They are not listed here. The above is only for illustrative purposes and is not intended to limit the scope of the claims of this invention.

[0090] In one embodiment, the aforementioned second inductor L r1It can be the transformer's own inductance or an external inductance. The inductance value in the resonant slot can be adjusted by changing the windings inside the magnetic component through any form of switch such as a switching assembly or relay, or by adding external magnetic components in series or parallel.

[0091] In one embodiment, the variation of the windings within the aforementioned magnetic component, or the addition of external magnetic components in series or parallel, can be achieved by configuring multiple switches between the windings. These multiple switches can be any type of switch, such as switching components, transistor switches, or relays.

[0092] In one embodiment, the switches S1, S2 and S3 can be any type of switch such as a switching assembly, a transistor switch or a relay.

[0093] Figure 6 This diagram shows the circuit block diagram and related operation control flow of the LLC resonant power converter. The LLC resonant power converter is used to convert the input DC voltage V in Converted to DC output voltage V o This circuit, designed to supply power to a load, includes a full-bridge / half-bridge switching circuit 601, a resonant tank and transformer circuit 603, a rectifier and filter circuit 605, and an external control circuit 607. The full-bridge / half-bridge switching circuit 601, controlled by the external control circuit 607, switches the upper or lower bridge switch to either side of the circuit. This allows the circuit to input a periodically varying switching signal to the resonant tank and transformer circuit 603, causing the current in the circuit to change sinusoidally. The rectifier and filter circuit 605, coupled to the secondary winding of the resonant tank and transformer 603, then rectifies and filters the current in the secondary winding, generating a DC current I. o And output DC voltage V o To be provided for use by the load.

[0094] The resonant tank and transformer functional block 603 includes a resonant tank (including a series-connected resonant inductor L) coupled to a full-bridge / half-bridge switching circuit 601. r Magnetizing inductance L m and resonant capacitor C r The LLC resonant power converter includes a transformer (containing a magnetic core, primary (main and secondary) windings, and secondary windings) coupled to the resonant slot. The secondary windings of the transformer are coupled to a rectifier and filter circuit 605 (rectified via a rectifier switch). During operation of the LLC resonant power converter, the rectifier and filter circuit 605 rectifies and filters the input secondary signal (current or voltage) to convert it into DC output, providing a DC output voltage V. oThe external control circuit 607 is coupled to the aforementioned full-bridge / half-bridge switching circuit 601, resonant tank and transformer 603, and rectifier-filter circuit 605. The external control circuit 607 receives output voltage feedback, output current feedback, and external communication signals (to confirm output voltage) from the LLC resonant power converter. Based on these feedbacks, it outputs switching signals to control the on / off state of the upper or lower bridge switching switch in the full-bridge / half-bridge circuit 601. Furthermore, based on the received output voltage and current feedback, it outputs corresponding resonant tank adjustment signals to the resonant tank and transformer, thereby dynamically adjusting the magnetizing inductance L. m Resonant capacitor C r and resonant inductor L r The size is adjusted to achieve the purpose of adjusting the range of its output voltage and output current.

[0095] In a preferred embodiment, the external control circuit 607 may be a microprocessor, a microcontroller (MCU), a digital signal processor (DSP), or a computing device with similar functions.

[0096] Basically, once the circuit topology of the LLC resonant power converter is determined, its resonant slot parameter L... r L m and C r It has been largely determined that it cannot be adjusted for different operating scenarios. In other words, it is impossible to adjust the range of its output voltage and output current according to operational needs.

[0097] This invention will use the switching frequency (operating frequency) f s Operating at Mega Hz and above, the size of magnetic components is reduced, and stray characteristics of magnetic components are reduced by using printed circuit board windings. L is achieved through series and parallel connection of transformer windings. r L m C r Fine-tuning or external series-parallel connection L r1 L m1 C r1 To adjust the parameters of the resonant slot, the LLC resonant power converter can achieve the goal of widening the voltage and current range.

[0098] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention and its benefits have been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the embodiments described above, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the scope of the claims of the present invention.

Claims

1. An LLC resonant power converter with printed circuit board windings, characterized in that, include: A switching circuit is electrically coupled to an input DC voltage to convert the DC voltage into a switching signal; A resonant slot is electrically coupled to the switching circuit. The resonant slot consists of a resonant inductor, a magnetizing inductor, and a resonant capacitor, and is used to receive the switching signal to provide primary side current. A transformer circuit is electrically coupled to the resonant slot. This transformer circuit comprises multiple discrete transformers, each having a primary winding and a secondary winding. The primary and secondary windings are mounted on a printed circuit board to effectively reduce stray characteristics caused by the windings. The printed circuit board includes multiple through holes, a multilayer board, and multiple windings. The positions of the multiple through holes correspond to the magnetic cores of multiple discrete transformers, allowing each magnetic core of the multiple discrete transformers to pass through its corresponding multiple through holes. The multiple windings disposed on each layer of the multilayer board each surround the magnetic cores of the multiple discrete transformers to generate induced electromotive force. The multiple windings disposed on each layer of the multilayer board are either the primary windings or the secondary windings. In this process, the primary winding of an individual transformer is dynamically selected to be electrically coupled or isolated from the resonant slot, and is also dynamically selected to be connected in series or in parallel with the primary windings of other transformers to form a dynamically changing equivalent primary winding. This allows the resonant slot electrically coupled to the transformer circuit to be finely adjusted while maintaining the turns ratio. A rectifier and filter circuit is coupled to the transformer circuit to rectify and filter the secondary current output from the secondary winding of the transformer circuit in order to provide an output voltage. Wherein, one end of the resonant inductor is electrically coupled to the switching circuit, and the other end is connected in series with the equivalent primary winding; the magnetizing inductor is connected in series with the resonant inductor, one end of the resonant capacitor is connected in series with the magnetizing inductor, and the other end is electrically coupled to the switching circuit; the magnetizing inductor is connected in parallel with the equivalent primary winding. The resonant slot dynamically adjusts the gain curve of the LLC resonant power converter according to the output current requirements of the LLC resonant power converter by electrically coupling an external magnetizing inductor, an external resonant inductor, or an external resonant capacitor.

2. The LLC resonant power converter with printed circuit board windings according to claim 1, characterized in that, The aforementioned equivalent primary winding that forms a dynamic change, the external magnetizing inductor electrically coupled to the resonant slot, the external resonant inductor, or the external resonant capacitor are dynamically adjusted through a configuration of multiple switches.

3. The LLC resonant power converter with printed circuit board windings according to claim 2, characterized in that, This switch includes various types of transistor switch assemblies and relay switches.

4. The LLC resonant power converter with printed circuit board windings according to claim 2, characterized in that, The external excitation inductor is either the leakage inductance of the transformer itself or an external inductance. The inductance value of the resonant slot is adjusted by changing the winding of the magnetic component of the resonant slot through the aforementioned multiple switches, or by connecting external magnetic components in series and parallel.

5. The LLC resonant power converter with printed circuit board windings according to claim 4, characterized in that, The external magnetizing inductor is used to dynamically adjust one of the resonant slot parameters K, i.e., the inductance ratio, so that the gain curve of the LLC resonant power converter is dynamically adjusted according to the demand of its output current Io.

6. The LLC resonant power converter with printed circuit board windings according to claim 2, characterized in that, The aforementioned external resonant capacitor is either a stray capacitor in the circuit or an externally added capacitor. The capacitance value within the resonant slot is changed by adjusting the series and parallel connection of the capacitors through the aforementioned multiple switches.

7. The LLC resonant power converter with printed circuit board windings according to claim 6, characterized in that, The external resonant capacitor is used to adjust the quality factor Q while keeping the inductance ratio K constant, so that the gain curve of the LLC resonant power converter is dynamically adjusted according to the demand of its output current Io.

8. The LLC resonant power converter with printed circuit board windings according to claim 2, characterized in that, The external resonant inductor is either the transformer's own inductance or an externally applied inductor. The inductance value in the resonant slot is adjusted by changing the windings within the magnetic components of the resonant slot through the aforementioned multiple switches, or by using externally applied magnetic components in series and parallel.

9. The LLC resonant power converter with printed circuit board windings according to claim 8, characterized in that, The external resonant inductor is used to adjust the quality factor Q and the inductance ratio K, so that the gain curve of the LLC resonant power converter is dynamically adjusted according to the output current Io demand.

10. The LLC resonant power converter with printed circuit board windings according to claim 2, characterized in that, The aforementioned multiple switch configurations, through an external controller electrically coupled to the LLC resonant power converter, output corresponding resonant tank adjustment signals to the resonant tank and the transformer respectively based on the output voltage feedback and output current feedback received by the external controller, so as to adjust the range of output voltage and output current of the LLC resonant power converter.

Images