Non-isolated push-pull converter
By adjusting the winding turns ratio and core structure using a non-isolated push-pull converter, the problems of high copper wire loss and excessively high cross-voltage in traditional voltage converters at high conversion ratios are solved, achieving low-loss and high-efficiency current conversion.
Patent Information
- Application Number
- CN202510641389.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-08-12
- Filing Date
- 2025-05-19
- Publication Date
- 2026-02-13
AI Technical Summary
Traditional voltage converters suffer from high copper wire losses at high conversion ratios, and the voltage across the primary circuit can easily exceed the withstand limit of the switching elements, leading to component damage or shortened lifespan.
A non-isolated push-pull converter is used. By adjusting the turns ratio of the primary and secondary windings and combining it with the core structure, the current ratio can be controlled and the cross voltage of the primary circuit can be reduced.
It achieves low-loss and high-efficiency current conversion while reducing the cross voltage of switching elements, increasing power density and reducing cost.
Smart Images
Figure CN121530186A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to voltage converters, and in particular to a non-isolated push-pull converter with reduced number of components and losses. BACKGROUND
[0002] Voltage converters can be used to step up or step down between different types of circuits for better performance. Conventional voltage converters are usually isolated converters. However, in cases where the circuit requires a high conversion ratio, a high turns ratio is usually required. As a result, the copper loss is also high. SUMMARY
[0003] According to an embodiment of the present disclosure, a non-isolated push-pull converter is provided, comprising a first primary winding, a second primary winding, a first secondary winding, a second secondary winding, a first feedback switch and a second feedback switch. The first primary winding is coupled in series with a first switch between an input terminal and a first node, and the second primary winding is coupled in series with a second switch between the input terminal and a second node. The first secondary winding is coupled between the first node and a third node, and the second secondary winding is coupled between the second node and the third node. The first feedback switch is coupled between the second node and a ground terminal, and the second feedback switch is coupled between the first node and the ground terminal. The third node is coupled to an output terminal.
[0004] In a positive half cycle, the first switch and the first feedback switch are turned on, and the second switch and the second feedback switch are turned off. The first primary winding receives an input current from the input terminal, and transmits the input current to the output terminal through the first secondary winding. The second secondary winding generates an induced current according to the input current, and transmits the induced current to the output terminal.
[0005] In a negative half cycle, the second switch and the second feedback switch are turned on, and the first switch and the first feedback switch are turned off. The second primary winding receives the input current from the input terminal, and transmits the input current to the output terminal through the second secondary winding. The first secondary winding generates the induced current according to the input current, and transmits the induced current to the output terminal through the output inductor.
[0006] According to an embodiment of the present disclosure, the non-isolated push-pull converter further comprises a magnetic core having a first column and a second column. The first primary winding is wound around the first column to form a first primary winding layer, the second primary winding is wound around the first column to form a second primary winding layer, the first secondary winding is wound around the second column to form a first secondary winding layer, and the second secondary winding is wound around the second column to form a second secondary winding layer.
[0007] The first primary winding has a first number of turns, the second primary winding has a second number of turns, the first secondary winding has a third number of turns, and the second secondary winding has a fourth number of turns. In one embodiment, the first number of turns, the second number of turns, the third number of turns, and the fourth number of turns are equal. In another embodiment, the first number of turns and the second number of turns are equal, and the third number of turns and the fourth number of turns are equal. BRIEF DESCRIPTION OF DRAWINGS
[0008] Figure 1 A circuit diagram of a non-isolated push-pull converter according to an embodiment of the present disclosure.
[0009] Figure 2A A circuit diagram of the non-isolated push-pull converter of Figure 1
[0010] Figure 2B A winding diagram of the non-isolated push-pull converter of Figure 2A
[0011] Figure 3A A circuit diagram of the non-isolated push-pull converter of Figure 1
[0012] Figure 3B A winding diagram of the non-isolated push-pull converter of Figure 3A
[0013] Wherein, the reference numerals are explained as follows:
[0014] 100: non-isolated push-pull converter
[0015] Vin: input terminal
[0016] Vout: output terminal
[0017] GND: ground terminal
[0018] NP1, NP2: primary winding
[0019] NS1, NS2: secondary winding
[0020] S1, S2: switch
[0021] SR1, SR2: feedback switch
[0022] N1, N2, N3: node
[0023] L: output inductor
[0024] IPP, IPN: main current
[0025] ISP, ISN: induced current
[0026] Iout: output current
[0027] 200: schematic diagram
[0028] 210: magnetic core
[0029] 212, 214: magnetic column DETAILED DESCRIPTION
[0030] In conventional transformer winding, if a desired current ratio is to be achieved, the primary winding and the secondary winding are usually directly adjusted to the desired current ratio. For example, if a 1:3 ratio of input current to output current is desired, the turns ratio of the primary winding and the secondary winding is directly adjusted to 3:1, and the induced current generated by the secondary winding is directly taken as the output current. In addition, the cross voltage of the primary circuit of a conventional push-pull converter is usually twice the input voltage (e.g., if the input voltage is 60V, the cross voltage of the primary circuit is 120V). However, this can cause the cross voltage of the primary circuit to exceed the upper limit of the withstand voltage of the switching element (e.g., the common upper limit of the switching voltage is 80-100V), thereby causing the switching element to be damaged or its service life to be shortened.
[0031] Figure 1 FIG. 1 shows a circuit diagram of a non-isolated push-pull converter 100 according to an embodiment of the present disclosure. The non-isolated push-pull converter includes primary windings NP1 and NP2, secondary windings NS1 and NS2, switches S1 and S2, and feedback switches SR1 and SR2. The primary winding NP1 and the switch S1 are coupled in series between an input terminal Vin and a node N1, the primary winding NP2 and the switch S2 are coupled in series between the input terminal Vin and a node N2, the secondary winding NS1 is coupled between the nodes N1 and N3, the secondary winding NS2 is coupled between the nodes N2 and N3, the feedback switch SR1 is coupled between the node N2 and a ground terminal GND, and the feedback switch SR2 is coupled between the node N1 and the ground terminal GND.
[0032] The non-isolated push-pull converter 100 further includes an output inductor L coupled between the node N3 and an output terminal Vout. The input terminal Vin is coupled to an input power supply (e.g., a supply voltage), and the output terminal Vout is configured to output a current flowing through the output inductor L to a backend circuit. In addition, the non-isolated push-pull converter 100 further includes an output load including a capacitor and a resistor coupled between the ground terminal GND and the output terminal Vout. Furthermore, the feedback switches SR1 and SR2 can be transistors, diodes, or other switching elements.
[0033] When the non-isolated push-pull converter 100 is in a positive half-cycle, switch S1 and feedback switch SR1 are turned on, while switch S2 and feedback switch SR2 are turned off. This allows a current to flow from the input terminal Vin through the primary winding NP1, switch S1, secondary winding NS1, and output inductor L to the output terminal Vout. Simultaneously, due to electromagnetic induction between the primary winding NP1 and the secondary windings NS1 and NS2, an induced current flows from the ground terminal GND through the feedback switch SR1, secondary winding NS2, and output inductor L to the output terminal Vout. Therefore, the current flowing out of the output terminal Vout has the sum of this induced current and the current value of the feedback current, thus increasing the current flowing out of the output terminal Vout.
[0034] Figure 2A for Figure 1 The circuit diagram of the non-isolated push-pull converter 100 during the positive half-cycle is shown. As shown, since switch S2 and feedback switch SR2 are open during the positive half-cycle, the current flowing to nodes N1 and N2 will not flow into the loop marked "x". During the positive half-cycle, switch S1 and feedback switch SR1 are on. Therefore, a main current IPP (e.g., input current) flows from the input terminal Vin through the primary winding NP1, switch S1, secondary winding NS1, and output inductor L, and exits from the output terminal Vout. At this time, due to the electromagnetic induction between the primary winding NP1 and the secondary windings NS1 and NS2, another induced current ISP flows from the ground terminal GND through the feedback switch SR1, secondary winding NS2, and output inductor L, and exits from the output terminal Vout. That is, the output current Iout flowing out at the output terminal Vout is the sum of the main current IPP and the induced current ISP.
[0035] Among them, such as Figure 2A As shown, since the main current IPP flows through the primary winding NP1 and the secondary winding NS1, the total number of turns of the windings through which the main current IPP flows can be considered as the sum of the number of turns in the primary winding NP1 (e.g., A turns) and the number of turns in the secondary winding NS1 (e.g., B turns). Assuming the number of turns in the secondary winding NS2 is C turns, the ratio of the main current IPP, the induced current ISP, and the output current Iout can be obtained as C:(A+B):(A+B+C). Therefore, by appropriately adjusting the turns ratio of the primary winding NP1 and the secondary windings NS1 and NS2, the corresponding proportion of the output current Iout can be obtained.
[0036] Figure 2B for Figure 2AA schematic diagram 200 of the winding of a non-isolated push-pull converter 100 is shown. As shown, the non-isolated push-pull converter 100 also includes a magnetic core 210 with magnetic posts 212 and 214. Primary windings NP1 and NP2 are wound around magnetic post 212, forming two different primary winding layers, while secondary windings NS1 and NS2 are wound around magnetic post 214, forming two different secondary winding layers. Since switch S2 and feedback switch SR2 are open during the positive half-cycle, the primary winding NP2, switch S2, and feedback switch SR2 are not shown. Figure 2B middle.
[0037] Similar to Figure 2A As shown, in Figure 2B In the first half-cycle, the main current IPP flows from the input terminal Vin through the primary winding NP1 and switch S1 to node N1. At this time, because the feedback switch SR2 is open, the main current IPP flows to the secondary winding NS1, and then through node N3 and output inductor L to the output terminal Vout. That is, during the positive half-cycle, the main current IPP in the primary winding NP1 flows counterclockwise. Next, the main current IPP flows from node N1 through the secondary winding NS1 to node N3, and then through output inductor L to the output terminal Vout. The main current IPP flowing through the secondary winding NS1 flows clockwise.
[0038] In response to the main current IPP, the induced current ISP flows from the ground terminal GND through the feedback switch SR1 to node N2. Since switch S2 is open during the positive half-cycle, the induced current ISP flows to the secondary winding NS2, and then through node N3 and the output inductor L to the output terminal Vout. Assume that the primary winding NP1 and the secondary windings NS1 and NS2 both have the same number of turns (e.g., ...). Figure 2B As shown, all are 1 turn), it can be deduced that the main current IPP and the induced current ISP have 2 turns and 1 turn respectively. Therefore, the ratio of the main current IPP to the induced current ISP is 1:2, and the ratio of the output current Iout to the main current IPP is 3:1.
[0039] Figure 3A for Figure 1The circuit diagram of the non-isolated push-pull converter 100 during the negative half-cycle is shown. Since switch S1 and feedback switch SR1 are open during the negative half-cycle, current flowing through nodes N1 and N2 will not flow into the loop marked "x". During the negative half-cycle, switch S2 and feedback switch SR2 are on. Therefore, a main current IPN flows from the input terminal Vin through the primary winding NP2, switch S2, secondary winding NS2, and output inductor L, exiting at the output terminal Vout. At this time, due to electromagnetic induction between the primary winding NP2 and the secondary windings NS1 and NS2, another induced current ISN flows from the ground terminal GND through the feedback switch SR2, secondary winding NS1, and output inductor L, exiting at the output terminal Vout. That is, the output current Iout flowing out at the output terminal Vout is the sum of the main current IPN and the induced current ISN.
[0040] Among them, such as Figure 3A As shown, since the main current IPN flows through the primary winding NP2 and the secondary winding NS2, the total number of turns of the windings through which the main current IPN flows can be considered as the sum of the number of turns in the primary winding NP2 (e.g., D turns) and the number of turns in the secondary winding NS2 (e.g., C turns). If the number of turns in the secondary winding NS1 is B turns, then the ratio of the main current IPN, the induced current ISN, and the output current Iout can be calculated as B:(C+D):(B+C+D). Therefore, by appropriately adjusting the turns ratio of the primary winding NP2 and the secondary windings NS1 and NS2, the corresponding proportion of the output current Iout can be obtained.
[0041] Figure 3B for Figure 3A A schematic diagram 200 of the windings of a non-isolated push-pull converter 100 is shown. Since switch S1 and feedback switch SR1 are open during the negative half-cycle, the primary winding NP1, switch S1, and feedback switch SR1 are not shown. Figure 3B Middle. Similar to Figure 3A As shown, in Figure 3B In the first half of the cycle, the main current IPN flows from the input terminal Vin through the primary winding NP2 and switch S2 to node N2. At this time, because the feedback switch SR1 is open, the main current IPN flows to the secondary winding NS2, and then through node N3 and output inductor L to the output terminal Vout. That is, during the negative half-cycle, the main current IPN in the primary winding NP2 flows clockwise. Next, the main current IPN flows from node N2 through the secondary winding NS2 to node N3, and then through output inductor L to the output terminal Vout. The main current IPN flowing through the secondary winding NS2 flows counterclockwise.
[0042] In response to the main current IPN, the induced current ISN flows from the ground terminal GND through the feedback switch SR2 to node N1. Since switch S1 is open during the negative half-cycle, the induced current ISN flows to the secondary winding NS1, and then through node N3 and the output inductor L to the output terminal Vout. Assume that the primary winding NP2 and the secondary windings NS1 and NS2 both have the same number of turns (e.g., ...). Figure 3B As shown, all are 1 turn), it can be deduced that the main current IPN and the induced current ISN have 2 turns and 1 turn respectively. Therefore, the ratio of the main current IPN to the induced current ISN is 1:2, and the ratio of the output current Iout to the main current IPN is 3:1.
[0043] In one embodiment, the number of turns in the primary windings NP1 and NP2 is set to 2 turns each, and the number of turns in the secondary windings NS1 and NS2 is set to 1 turn each. Thus, during the positive half-cycle, the main current IPP flows through 3 turns in the primary winding NP1 and the secondary winding NS1, while the induced current ISP flows through 1 turn in the secondary winding NS2, resulting in a ratio of 1:3:4 for the main current IPP, the induced current ISP, and the output current Iout. Therefore, during the positive half-cycle (e.g., when the non-isolated push-pull converter 100 performs a step-down operation), the main current IPP flowing through the secondary winding NS1 is less than the induced current ISP flowing through the secondary winding NS2.
[0044] During the negative half-cycle, the main current IPN flows through 3 turns of the primary winding NP2 and the secondary winding NS2, while the induced current ISN flows through 1 turn of the secondary winding NS1, resulting in a ratio of 1:3:4 for the main current IPN, the induced current ISN, and the output current Iout. Therefore, during the negative half-cycle, the main current IPN flowing through the secondary winding NS2 is less than the induced current ISN flowing through the secondary winding NS1.
[0045] Similarly, in another embodiment, the number of turns in the primary windings NP1, NP2 and the secondary windings NS1, NS2 is each set to 1 turn. Thus, during the positive half-cycle, the main current IPP and the induced current ISP flow through 2 turns and 1 turn respectively, resulting in a current ratio of 1:2. During the negative half-cycle, the main current IPN and the induced current ISN flow through 2 turns and 1 turn respectively, again resulting in a current ratio of 1:2. Therefore, similar to the embodiment described above where the number of turns in the primary windings NP1, NP2 and the secondary windings NS1, NS2 are set to 2 turns and 1 turn respectively, during the positive half-cycle, the main current IPP flowing through the secondary winding NS1 is less than the induced current ISP flowing through the secondary winding NS2. During the negative half-cycle, the main current IPN flowing through the secondary winding NS2 is less than the induced current ISN flowing through the secondary winding NS1.
[0046] The non-isolated push-pull converter architecture provided by the embodiments of this disclosure enables an input current to output current ratio of 1:3 while maintaining the same turns ratio between the primary and secondary windings, thereby reducing winding losses (e.g., copper losses). Simultaneously, the circuit interconnect architecture provided by this disclosure reduces the primary-side voltage across the push-pull converter (e.g., dropping to approximately 1.33 times the input voltage), and compared to common full-bridge or resonant converters, it has fewer switches, thereby increasing power density and reducing cost.
Claims
1. A non-isolated push-pull converter, comprising: A first primary winding is connected in series with a first switch between an input terminal and a first node; A second primary winding is coupled to a second switch between the input terminal and a second node; A first and a second side winding are coupled between the first node and a third node; A second secondary winding is coupled between the second node and the third node; A first feedback switch is coupled between the second node and a ground terminal; as well as A second feedback switch is coupled between the first node and the ground terminal. The third node is coupled to an output terminal.
2. The non-isolated push-pull converter as claimed in claim 1, wherein in one positive half-cycle: The first switch and the first feedback switch are turned on, and the second switch and the second feedback switch are turned off; The first primary winding receives an input current from the input terminal and transmits it to the output terminal through the first secondary winding; and The second secondary winding generates an induced current based on the input current and transmits it to the output terminal.
3. The non-isolated push-pull converter as claimed in claim 1, wherein in one negative half-cycle: The second switch and the second feedback switch are turned on, while the first switch and the first feedback switch are turned off; The second primary winding receives an input current from the input terminal and transmits it to the output terminal through the second secondary winding; and The first and second side windings generate an induced current based on the input current and transmit it to the output terminal.
4. The non-isolated push-pull converter as claimed in claim 1 further includes an output inductor coupled between the third node and the output terminal.
5. The non-isolated push-pull converter as claimed in claim 1, wherein when the first primary winding and the second primary winding respectively receive current, the current flowing through the first primary winding and the current flowing through the second primary winding flow in opposite directions.
6. The non-isolated push-pull converter as claimed in claim 1, wherein when the first secondary winding and the second secondary winding respectively receive current, the current flowing through the first secondary winding and the current flowing through the second secondary winding flow in opposite directions.
7. The non-isolated push-pull converter as claimed in claim 1, further comprising a magnetic core having a first post and a second post, wherein: The first primary winding is wound around the first post to form a first primary winding layer; The second primary winding is wound around the first post to form a second primary winding layer; The first and second side windings are wound around the second post to form a first and second side winding layer; as well as The second secondary side winding is wound around the second post to form a second secondary side winding layer.
8. The non-isolated push-pull converter as described in claim 7, wherein: When in a positive half-cycle, the first primary winding layer is connected in series with the first secondary winding layer through the first switch, and the second secondary winding layer generates an induced current. as well as When in a negative half-cycle, the second primary winding layer is connected in series with the second secondary winding layer through the second switch, and the first secondary winding layer generates the induced current.
9. The non-isolated push-pull converter as described in claim 8, wherein: The first primary winding has a first number of turns, the second primary winding has a second number of turns, the first secondary winding has a third number of turns, and the second secondary winding has a fourth number of turns. The sum of the first number of turns and the third number of turns equals a first count value, and the sum of the second number of turns and the fourth number of turns equals a second count value; When in the positive half-cycle, the first primary winding receives an input current, and the ratio of the input current to the induced current is the ratio of the fourth number of turns to the first count value. as well as When in the negative half-cycle, the second primary winding receives the input current, and the ratio of the input current to the induced current is the ratio of the third number of turns to the second count value.
10. The non-isolated push-pull converter as described in claim 9, wherein: When it is in the positive half-cycle, the current flowing through the first secondary winding is less than the current flowing through the second secondary winding; as well as When in the negative half-cycle, the current flowing through the first secondary winding is greater than the current flowing through the second secondary winding.
11. The non-isolated push-pull converter of claim 9, wherein the first number of turns, the second number of turns, the third number of turns, and the fourth number of turns are all the same.
12. The non-isolated push-pull converter of claim 9, wherein the first number of turns and the second number of turns are equal, and the third number of turns and the fourth number of turns are equal.