Transformer

Abstract

The present disclosure provides a conversion device, comprising a first end, a second end, a first-side switch circuit, a second-side switch circuit and a transformer. The first end comprises a first positive electrode and a first negative electrode. The second end comprises a second positive electrode and a second negative electrode. The first-side switch circuit is coupled to the first end and comprises a first bridge arm and a second bridge arm, the two ends of the first bridge arm are respectively coupled to the first positive electrode and the first negative electrode, and the two ends of the second bridge arm are respectively coupled to the first positive electrode and the second positive electrode. The transformer comprises a first-side winding coupled to the first-side switch circuit and a second-side winding coupled to the second-side switch circuit, and the turns ratio of the first-side winding and the second-side winding is N:1.

Description

Technical Field

[0001] The present disclosure relates to a conversion device, and in particular to a conversion device capable of realizing a non-integer multiple voltage transformation ratio. Background Art

[0002] With the rapid development of the Internet and artificial intelligence, high-efficiency and high-power-density power supplies have become quite common. For example, when transmitting power, in order to reduce the loss during the transmission process, the voltage needs to be increased from 12V to 54V, and when the power is actually supplied, the voltage needs to be reduced from 54V to 12V. Since 12V and 54V are non-integer multiples, the structure or control method of the transformer needs to be adjusted accordingly to achieve a non-integer multiple voltage ratio.

[0003] There are two ways to achieve non-integer multiple (taking N+0.5 times as an example) voltage transformation in existing conversion devices. One way is to directly adjust the turns ratio between the primary winding and the secondary winding of the transformer to a non-integer multiple. However, since the number of turns must be an integer, the transformer winding turns ratio must be set to (2N+1):2 to achieve a voltage transformation ratio of N+0.5, that is, the total number of turns of the transformer winding is at least 2N+3. Therefore, if the total number of turns of this voltage transformation method is too much, it will lead to excessive winding losses, thereby affecting the efficiency of the transformer. Another way is to maintain the transformer winding turns ratio at (N+1):1, and achieve a voltage transformation ratio of N+0.5 by adjusting the switching frequency of the switching circuit. However, since the switching frequency deviates from the resonant operating point, the resonant parameters are difficult to design, and the inductance of the resonant inductor increases, causing the magnetizing inductance of the transformer to decrease. Therefore, the voltage conversion loss of the conversion device increases.

[0004] Therefore, how to develop a conversion device that can improve the above-mentioned prior art is an urgent need. Summary of the invention

[0005] The main purpose of the present disclosure is to provide a conversion device, wherein the turns ratio of the transformer is N:1, wherein N is a positive integer, and a non-integer voltage conversion ratio is achieved by adjusting the connection relationship of the switch circuit on the high-voltage side. Thus, the conversion device does not increase the winding loss of the transformer without increasing the number of turns of the transformer, and because the switching frequency of the switch circuit is equal to the resonant frequency, it is easy to design and optimize the resonant parameters, and the inductance of the resonant inductor is reduced, resulting in an increase in the excitation inductance of the transformer, thereby improving the voltage conversion efficiency of the conversion device.

[0006] To achieve the above-mentioned purpose, the present disclosure provides a conversion device, comprising a first end, a second end, a first side switch circuit, a second side switch circuit and a transformer. The first end comprises a first positive electrode and a first negative electrode. The second end comprises a second positive electrode and a second negative electrode. The first side switch circuit is coupled to the first end and comprises a first bridge arm and a second bridge arm, the two ends of the first bridge arm are respectively coupled to the first positive electrode and the first negative electrode, and the two ends of the second bridge arm are respectively coupled to the first positive electrode and the second positive electrode. The transformer is coupled between the first side switch circuit and the second side switch circuit, and the transformer comprises a first side winding coupled to the first side switch circuit and a second side winding coupled to the second side switch circuit, the turns ratio of the first side winding and the second side winding is N:1, and the ratio of the voltage of the first end to the voltage of the second end is (N+0.5):1, where N is a positive integer. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Schematic diagram of the circuit structure of the conversion device of the preferred embodiment of the present disclosure.

[0008] Figure 2 for Figure 1 Schematic diagram of the circuit operation of the conversion device in the first working state.

[0009] Figure 3 for Figure 1 Schematic diagram of the circuit operation of the conversion device in the second working state.

[0010] Figure 4 for Figure 1 Schematic diagram of the voltage waveform of the conversion device.

[0011] Figure 5 for Figure 1 Schematic diagram of the current waveform of the conversion device.

[0012] Figure 6 Schematic diagram of the circuit structure of a conversion device according to another preferred embodiment of the present invention.

[0013] Figure 7 Schematic diagram of the circuit structure of a conversion device according to another preferred embodiment of the present invention.

[0014] Description of reference numerals:

[0015] 1: Transformation device

[0016] 10: First End

[0017] 11: Second End

[0018] 12: First side switch circuit

[0019] 121: First bridge arm

[0020] 122: Second bridge arm

[0021] 13: Second side switch circuit

[0022] 131: Switching circuit group

[0023] A: First Node

[0024] B: Second node

[0025] C: The third node

[0026] D: Fourth Node

[0027] V1: First side voltage

[0028] V1+: First positive electrode

[0029] V1-: First negative electrode

[0030] V2: Second side voltage

[0031] V2+: Second positive electrode

[0032] V2-: Second negative electrode

[0033] C1: First side capacitor

[0034] C2: Second side capacitor

[0035] Cr: resonant capacitor

[0036] Cb: DC blocking capacitor

[0037] Lr: resonant inductance

[0038] Lm: magnetizing inductance

[0039] L1: First side inductor

[0040] L2-: Second side inductor

[0041] Q1: First switch

[0042] Q2: Second switch

[0043] Q3: The third switch

[0044] Q4: The fourth switch

[0045] Q5: The fifth switch

[0046] Q6: The sixth switch

[0047] T: Transformer

[0048] T1: primary winding

[0049] T2, T3: Second side winding DETAILED DESCRIPTION

[0050] Some typical embodiments that embody the features and advantages of the present disclosure will be described in detail in the following description. It should be understood that the present disclosure can have various changes in different implementations without departing from the scope of the present disclosure, and the descriptions and illustrations therein are essentially for illustrative purposes, rather than for limiting the present disclosure.

[0051] See also Figure 1 , Figure 1 Schematic diagram of the circuit structure of the conversion device of the preferred embodiment of the present disclosure. In this embodiment, the conversion device 1 is a full-bridge LLC resonant conversion device, and the conversion device 1 includes a first end 10, a second end 11, a first side switch circuit 12, a second side switch circuit 13 and a transformer T. The first end 10 has a first side voltage V1, and the first end 10 includes a first positive electrode V1+ and a first negative electrode V1-. The second end 11 has a second side voltage V2, and the second end 11 includes a second positive electrode V2+ and a second negative electrode V2-, wherein the first negative electrode V1- and the second negative electrode V2- are grounded and electrically connected to each other. The first side switch circuit 12 is coupled to the first end 10, and the first side switch circuit 12 includes a first bridge arm 121 and a second bridge arm 122. The two ends of the first bridge arm 121 are respectively coupled to the first positive electrode V1+ and the first negative electrode V1-, and the two ends of the second bridge arm 122 are respectively coupled to the first positive electrode V1+ and the second positive electrode V2+. The second side switch circuit 13 is coupled to the second end 11, wherein the second side switch circuit 13 may be, for example but not limited to, a center tap rectifier circuit, a full bridge rectifier circuit, or a half bridge rectifier circuit. The transformer T is coupled between the first side switch circuit 12 and the second side switch circuit 13, and the transformer T includes at least one first side winding and at least one second side winding, wherein at least one first side winding is coupled to at least one second side winding. The first side winding is coupled to the first side switch circuit 12, and the second side winding is coupled to the second side switch circuit 13, wherein the turns ratio of the first side winding to the second side winding is N:1, and N is a positive integer.

[0052] The ratio of the number of turns of the first side winding and the second side winding of the conversion device 1 disclosed in the present invention is N:1, and by coupling the second bridge arm 122 to the second end 11, a non-integer multiple voltage ratio is achieved. For example, the conversion device 1 can be divided into a first working state and a second working state under different switch controls. In the first working state, a part of the energy of the first end 10 is transferred to the second end 11 through the magnetic coupling of the transformer T, and the other part of the energy is transferred to the second end 11 through the second bridge arm 122. In the second working state, the energy of the first end 10 is transferred to the second end 11 through the magnetic coupling of the transformer T. In this way, the conversion device 1 can achieve a non-integer multiple voltage ratio. In the above example, the conversion device 1 receives the voltage through the first end 10 and outputs the voltage from the second end 11. Of course, in other embodiments, the conversion device 1 can be changed to receive the voltage through the second end 11 and output the voltage from the first end 10, and in this case, the conversion device 1 can also achieve a non-integer multiple voltage ratio by the same principle, and the difference is only the difference in the direction of the voltage or current, so its operation process is not described in detail here.

[0053] The transformer turns ratio of the conversion device 1 disclosed in the present invention is N:1, and a non-integer voltage transformation ratio is achieved by adjusting the connection relationship of the switch circuit on the high-voltage side. In this way, the conversion device does not increase the number of turns of the transformer, and does not increase the winding loss of the transformer. Because the switching frequency of the switch circuit is approximately equal to the resonant frequency, it is easy to design and optimize the resonant parameters, and the inductance of the resonant inductor is reduced, resulting in an increase in the excitation inductance of the transformer, thereby improving the voltage conversion efficiency of the conversion device.

[0054] In a preferred embodiment of the present disclosure, the transformer T is a center-tapped transformer and includes a first side winding T1 and two second side windings T2 and T3 coupled in series, wherein the turns ratio of the first side winding T1 and the two second side windings T2 and T3 is N:1:1, but the actual implementation of the transformer T is not limited thereto.

[0055] The first bridge arm 121 includes a first switch Q1 and a second switch Q2 coupled in series, and a first node A is formed between the first switch Q1 and the second switch Q2. The second bridge arm 122 includes a third switch Q3 and a fourth switch Q4 coupled in series, and a second node B is formed between the third switch Q3 and the fourth switch Q4. The first side winding T1 is coupled in series between the first node A and the second node B, and a third node C is formed between the first node A and the first side winding T1.

[0056] In some embodiments, the conversion device 1 further includes a first side capacitor C1 and a second side capacitor C2, wherein the first side capacitor C1 is coupled in parallel to the first end 10, and the second side capacitor C2 is coupled in parallel to the second end 11. The equivalent magnetizing inductance Lm of the transformer T is as follows: Figure 1As shown, the excitation inductor Lm is coupled in parallel to the first winding T1, and the two ends of the excitation inductor Lm are respectively coupled to the second node B and the third node C. The conversion device 1 further includes a resonant capacitor Cr and a resonant inductor Lr, the resonant capacitor Cr and the resonant inductor Lr are coupled in series between the first node A and the third node C, and the resonant capacitor Cr and the resonant inductor Lr have a resonant frequency f r , resonant frequency f r The resonant inductor Lr is equal to or approximately equal to the switching frequency of the first-side switch circuit 12 , wherein the resonant inductor Lr is the equivalent leakage inductance of the transformer T or an inductance independent of the transformer T.

[0057] The second side switch circuit 13 includes a switch circuit set 131. In some embodiments, the switch circuit set 131 includes a fifth switch Q5 and a sixth switch Q6 coupled in series. The fifth switch Q5 and the sixth switch Q6 are respectively coupled to two ends of the two second side windings T2 and T3. There is a fourth node D between the two second side windings T2 and T3, and the fourth node D is coupled to the second positive electrode V2+.

[0058] In some embodiments, the switches Q1 - Q6 may be transistor switches, such as but not limited to metal oxide semiconductor field effect transistors (MOSFETs), bipolar junction transistors (BJTs), or insulated gate bipolar transistors (IGBTs).

[0059] To facilitate understanding of the disclosed technology, the following is Figure 1 The illustrated embodiment is taken as an example to specifically explain the circuit operation in the first and second working states.

[0060] In the following example, the conversion device 1 receives voltage through the first terminal 10 and outputs voltage through the second terminal 11. Of course, in other embodiments, the conversion device 1 can be changed to receive voltage through the second terminal 11 and output voltage through the first terminal 10. In this case, the conversion device 1 can also achieve a non-integer multiple voltage ratio by the same principle. The difference is only the difference in the direction of voltage or current, so its operation process will not be described in detail here. Figure 2 and Figure 3 . Figure 2 and Figure 3 They are Figure 1 Schematic diagram of the circuit operation of the conversion device in the first and second working states. The duty ratios of the first and second working states of the conversion device 1 are both 50%. In the first working state, the first switch Q1, the fourth switch Q4 and the fifth switch Q5 are turned on, and the second switch Q2, the third switch Q3 and the sixth switch Q6 are turned off. The voltage V between the first node A and the second node B is AB As shown in formula (1).

[0061] V AB =V1-V2 (1)

[0062] The voltage between the first node A and the second node B can also be expressed as a calculation formula related to the resonant capacitor Cr, the resonant inductor Lr and the second side voltage V2, as shown in Formula (2), wherein V Cr is the DC voltage of the resonant capacitor Cr, Δv Cr is the AC component of the voltage of the resonant capacitor Cr, V Lr is the voltage of the resonant inductor Lr.

[0063] V AB =V1-V2=V Cr +Δv Cr +V Lr +N·V2 (2)

[0064] In the second working state, the second switch Q2, the third switch Q3 and the sixth switch Q6 are turned on, and the first switch Q1, the fourth switch Q4 and the fifth switch Q5 are turned off. The switches in the first working state and the switches in the second working state are turned on 180 degrees out of phase, and the voltage between the first node A and the second node B is shown in formula (3),

[0065] V AB =0-V1 (3)

[0066] The voltage between the first node A and the second node B can also be expressed as a calculation formula related to the resonant capacitor Cr, the resonant inductor Lr and the second side voltage V2, as shown in Formula (4),

[0067] V AB =0-V1=V Cr +Δv Cr +V Lr -N·V2 (4)

[0068] In this embodiment, since the switching frequency of the first-side switch circuit 12 is approximately equal to the resonant frequency f r , so the AC component of the voltage of the resonant capacitor Cr is Δv Cr and the voltage V of the resonant inductor Lr Lr The sum can be approximately equal to 0. Therefore, formulas (2) and (4) are approximately simplified to formulas (5) and (6), respectively.

[0069] V 1 -V 2 =V Cr +N·V2 (5)

[0070] -V 1 =V Cr -N·V2 (6)

[0071] From formulas (5) and (6), we can get the DC component V of the first side voltage V1, the second side voltage V2 and the voltage of the resonant capacitor Cr: Cr The relationship is shown in formulas (7) and (8).

[0072] V1=(N+0.5)·V2 (7)

[0073] V Cr =-0.5·V2 (8)

[0074] From formulas (7) and (8), it can be seen that the voltage ratio of the first side voltage V1 to the second side voltage V2 is N+0.5:1, that is, a non-integer multiple voltage transformation ratio is achieved, and the DC component V of the voltage of the resonant capacitor Cr is Cr It is 0.5 times the second side voltage V2.

[0075] When the two ends of the second bridge arm 122 of the first side switch circuit 12 are respectively coupled to the first positive electrode V1+ and the second positive electrode V2+, the detailed working principle and waveform of the circuit structure can be found in Figure 4 and Figure 5 .in Figure 4 For this disclosure Figure 1 Schematic diagram of voltage waveform of the conversion device. The voltage V between the first node A and the second node B AB , the voltage V between the third node C and the second node B CB 、The voltage v of the resonant capacitor Cr Cr , the voltage V of the resonant inductor Lr Lr The voltage waveform of the second side voltage ripple ΔV2 is as follows: Figure 4 As shown. In the first working state and the second working state, the transmission modes of the current flowing from the first end 10 to the second end 11 are different, respectively. Therefore, the amplitude of the second side voltage ripple ΔV2 in the same switching cycle is not the same, and the frequency of the second side voltage ripple ΔV2 is equal to the switching frequency of the switching circuit. For example, in the first working state, the current flowing into the second side voltage V2 when the first switch Q1, the fourth switch Q4 and the fifth switch Q5 are turned on is relatively large, and in the second working state, the current flowing into the second side voltage V2 when the second switch Q2, the third switch Q3 and the sixth switch Q6 are turned on is relatively small. In other words, the change amplitude of the second side voltage ripple ΔV2 in the first working state is greater than the change amplitude in the second working state.

[0076] Figure 5 for Figure 1 Schematic diagram of the current waveform of the conversion device. Among them, the current flowing through the resonant inductor Lr is i Lr , the current flowing through the magnetizing inductor Lm is i Lm , the current flowing through the second winding T2 is i s , current iLr 、i Lm andi s The current waveform is as follows Figure 5 In the first working state, the current at the first end 10 flows through the first side switch circuit 12 and the transformer T, and then is transmitted to the second end 11 through the second side switch circuit 13. The current i flowing through the first winding T1 p =i Lr -i Lm , the current flowing through the second winding T2 after coupling is i s =N·i p At the same time, the current i Lr The load current of the conversion device 1 is i s +i Lr The DC value of the sum of the currents.

[0077] In the second working state, the current of the first terminal 10 flows through the first side switch circuit 12 and the transformer T, and then is transmitted to the second terminal 11 through the second side switch circuit 13. The current flowing through the first winding T1 is also i p =i Lr -i Lm , the current flowing through the second winding T2 is i s =N·i p At this time, the load current of the conversion device 1 is only the current i s The DC value, its current waveform also refers to Figure 5 as shown in .

[0078] In some embodiments, the conversion device 1 is not limited to a full-bridge LLC resonant conversion device, and can still be used for non-integer voltage adjustment. The following examples illustrate other implementations of the conversion device 1. Figure 6 , Figure 6 FIG. 1 is a schematic diagram of the circuit structure of another preferred embodiment of the conversion device disclosed in the present invention. The conversion device 1a of this embodiment is a switched capacitor conversion device. Figure 1 The transformation device 1, Figure 6 The conversion device 1a of the embodiment does not have a resonant capacitor Cr, a resonant voltage Lr, and the excitation inductance Lm is not shown, and the conversion device 1 of this embodiment further includes a first side inductance L1. In addition, the conversion device 1a of this embodiment is Figure 1 Similar components in the conversion device 1 are indicated by the same reference numerals, so they are not described here again. In this embodiment, the first side inductor L1 is coupled in series between the first positive electrode V1+ and the first side capacitor C1, and the first side voltage V1 and the first side inductor L1 form a constant current source, and the transformer T has a leakage inductance, and by reducing the capacitance of the first side capacitor C1, the first side capacitor C1 and the leakage inductance of the transformer T work together to generate an oscillating current.

[0079] See also Figure 7 , Figure 7 FIG. 1 is a schematic diagram of the circuit structure of another preferred embodiment of the conversion device disclosed in the present invention. The conversion device 1b of this embodiment is a hard-switching full-bridge conversion device. Figure 1 The transformation device 1, Figure 7 The conversion device 1b of the embodiment does not have the resonant capacitor Cr and the resonant voltage Lr, and the conversion device 1 of the embodiment further includes a second side inductor L2 and a DC blocking capacitor Cb. In addition, the conversion device 1b of the embodiment is Figure 1 Similar components in the conversion device 1 are denoted by the same reference numerals, and thus are not described in detail herein. In this embodiment, the second side inductor L2 is coupled in series between the second side switch circuit 13 and the second side capacitor C2, the DC blocking capacitor Cb is coupled in series between the first winding T1 and the first node A, and the transformer T has a leakage inductance.

[0080] It should be noted that the description of "equal to" mentioned in all the above embodiments of the present disclosure is not absolutely "equal to", for example: the switching frequency of the switching circuit is equal to the resonant frequency, and its "equal to" has an allowable error, and the allowable error is within ±10%, that is, the switching frequency of the switching circuit can be ±10% of the resonant frequency. Similarly, the description of numerical values ​​such as "duty cycle is 50%", "resonant frequency is equal to switching frequency", "N+0.5" or "0" mentioned in all the above embodiments of the present disclosure can also have an allowable error, and the allowable error is within ±10%.

[0081] In summary, the main purpose of the present disclosure is to provide a conversion device, the turns ratio of the transformer of which is N:1, and a non-integer voltage ratio is achieved by adjusting the connection relationship of the switch circuit on the high-voltage side. Thereby, the conversion device does not increase the winding loss of the transformer without increasing the number of turns of the transformer, and because the switching frequency of the switch circuit is approximately equal to the resonant frequency, it is easy to design and optimize the resonant parameters, and the inductance of the resonant inductor is reduced, resulting in an increase in the excitation inductance of the transformer, thereby improving the voltage conversion efficiency of the conversion device.

[0082] It should be noted that the above are only preferred embodiments for illustrating the present disclosure, and the present disclosure is not limited to the embodiments described. The scope of the present disclosure is determined by the protection scope of the relevant application documents. Moreover, the present disclosure may be modified in various ways by those skilled in the art, but they are all within the scope of protection of the relevant application documents.

Claims

1. A conversion device, comprising: A first end including a first positive electrode and a first negative electrode; A second end, including a second positive electrode and a second negative electrode; A first-side switch circuit, coupled to the first end, comprises: a first bridge arm, two ends of which are respectively coupled to the first positive electrode and the first negative electrode; and A second bridge arm, two ends of which are respectively coupled to the first positive electrode and the second positive electrode; a second-side switch circuit coupled to the second end; and a transformer, coupled between the first-side switch circuit and the second-side switch circuit, and comprising at least one first-side winding and at least one second-side winding, wherein the at least one first-side winding is coupled to the at least one second-side winding, the at least one first-side winding is coupled to the first-side switch circuit, and the at least one second-side winding is coupled to the second-side switch circuit; in, The turns ratio of the at least one first side winding to the at least one second side winding is N:1, and the ratio of the voltage of the first end to the voltage of the second end is (N+0.5):1, where N is a positive integer.

2. The conversion device as claimed in claim 1, in, The first bridge arm includes a first switch and a second switch coupled in series, and a first node is provided between the first switch and the second switch. The second switch bridge arm includes a third switch and a fourth switch coupled in series, and a second node is provided between the third switch and the fourth switch. Both ends of the first side winding are respectively coupled in series to the first node and the second node.

3. The conversion device as claimed in claim 2 further comprises a first side capacitor and a second side capacitor, wherein the first side capacitor is coupled in parallel to the first end, and the second side capacitor is coupled in parallel to the second end.

4. The conversion device as claimed in claim 2 further comprises a resonant capacitor and a resonant inductor, wherein the resonant capacitor and the resonant inductor are coupled in series between the first node and the first side winding, and the resonant capacitor and the resonant inductor have a resonant frequency, which is equal to the switching frequency of the first side switching circuit, wherein the resonant inductor is a leakage inductance of the transformer or an inductance independent of the transformer.

5. A conversion device as claimed in claim 3, wherein a first side inductor is coupled in series between the first positive electrode and the first side capacitor, and the voltage at the first end and the first side inductor form a constant current source, and the transformer has a leakage inductance, and the first side capacitor and the leakage inductance of the transformer work together to generate an oscillating current.

6. The conversion device as claimed in claim 3, wherein a second-side inductor is coupled in series between the second-side winding and the second-side capacitor, and a DC-blocking capacitor is coupled in series between the first-side winding and the first node.

7. A conversion device as claimed in claim 4, 5 or 6, wherein the conversion device has a first working state and a second working state, and the duty cycle of the first working state and the second working state is 50%. In the first working state, the first switch and the fourth switch are turned on, and the second switch and the third switch are turned off. In the second working state, the first switch and the fourth switch are turned off, and the second switch and the third switch are turned on. The switches in the first working state and the switches in the second working state are turned on 180 degrees out of phase.

8. A conversion device as claimed in claim 4, wherein the conversion device has a first working state and a second working state, the duty cycle of the first working state and the second working state are both 50%, in the first working state, the first switch and the fourth switch are turned on, and the second switch and the third switch are turned off, in the second working state, the first switch and the fourth switch are turned off, and the second switch and the third switch are turned on, the switch in the first working state and the switch in the second working state are turned on 180 degrees out of phase, wherein the DC voltage of the resonant capacitor is 0.5 times the voltage of the second end.

9. A conversion device as claimed in claim 7, wherein in the first working state, the current at the first end passes through the first side switch circuit and the transformer, and is then transmitted to the second end via the second side switch circuit, and at the same time flows directly to the second positive pole via the first side switch circuit.

10. A conversion device as claimed in claim 7, wherein the frequency of the voltage ripple of the voltage at the second end is equal to the switching frequency of the first side switching circuit and the second side switching circuit, and in the first working state, the change amplitude of the voltage ripple of the voltage at the second end in the first working state is greater than the change amplitude in the second working state.

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