Current doubling rectifier circuit and DC converter suitable for light load working state

Abstract

The application discloses a current doubling rectifier circuit and a DC converter suitable for a light no-load working state, relates to the technical field of power electronics, and adds a rectifying unit in a secondary rectifier circuit to cooperate with energy release of a secondary rectifier output filter unit, prevents reverse flow of current in the secondary rectifier output filter unit, avoids current backflow, and sets an intermediate tap on a secondary winding of a transformer, so that the number of turns of the secondary winding is reduced in a low-voltage output state.

Description

Technical Field

[0001] This invention relates to the field of power electronics, and more specifically, to a current-doubling rectifier circuit and a DC-DC converter suitable for light no-load operation. Background Technology

[0002] In low-voltage, high-current output DC-DC converters such as hard-switching half-bridge and full-bridge, soft-switching full-bridge phase-shifted, and asymmetrical half-bridge, the secondary rectifier circuit often adopts... Figure 1 and Figure 2 The conventional current double rectifier (CDR) circuit shown replaces the full-wave rectifier circuit to achieve a higher cost-performance ratio. Figure 1 This is a current-doubler rectifier circuit that uses diodes D1 and D2 connected in a common cathode configuration. Figure 2 This is a current-doubler rectifier circuit that uses diodes D1 and D2 connected in a common-anode configuration. Using a current-doubler rectifier circuit instead of a full-wave rectifier circuit reduces output voltage ripple, and allows for a reduction in the output filter capacitor capacity in the secondary rectifier circuit while maintaining the same output voltage ripple.

[0003] However, in traditional current-doubling rectifier circuits operating under light load or no-load conditions, when the load falls below a certain value, current reverse flow will occur in the output filter inductor L1 or L2, causing the output voltage U to drop. o Abnormal fluctuations can affect the efficiency of DC-DC converters and limit the application of current multiplier rectifier circuits. For example, when a battery is being charged, reverse current flow can damage the battery. Summary of the Invention

[0004] To address the current backflow problem that occurs in traditional current multiplier rectifier circuits under light load or no-load conditions, this invention proposes a current multiplier rectifier circuit suitable for light no-load conditions, avoiding current backflow under light no-load conditions, and exhibiting strong load adaptability. Furthermore, a DC-DC converter is proposed for various charging conversion applications.

[0005] To solve the above problems, the technical solution adopted in this application is as follows:

[0006] In a first aspect, the present invention proposes a current-doubling rectifier circuit suitable for light no-load operation, comprising: a primary-side bridge circuit, a transformer, and a secondary rectifier circuit. The output terminal of the primary-side bridge circuit is connected to the primary winding of the transformer. The secondary rectifier circuit includes a rectifier unit and a secondary rectifier output filter unit. The secondary winding of the transformer is sequentially connected to the rectifier unit and the secondary rectifier output filter unit. The secondary winding of the transformer is provided with an intermediate tap, which serves as a lead-out terminal of the secondary winding and is connected to the secondary rectifier output filter unit.

[0007] Preferably, the primary-side bridge circuit is a hard-switching full-bridge DC-DC converter circuit, a soft-switching full-bridge phase-shift DC-DC converter circuit, or an asymmetric half-bridge DC-DC converter circuit.

[0008] Preferably, the primary-side bridge circuit includes: a first input capacitor C1, a second input capacitor C2, a first switching transistor Q1, a second switching transistor Q2, a third input capacitor C3, and an input voltage U. 1N The positive terminals of the capacitors are connected to one end of the first input capacitor C1 and the drain of the first switching transistor Q1, respectively. The other end of the first input capacitor C1 is connected to one end of the second input capacitor C2, and the other end of the second input capacitor C2 is connected to the input voltage U. 1N The negative terminal of the first switching transistor Q1 is connected to one end of the third input capacitor C3 and the drain of the second switching transistor Q2. The other end of the third input capacitor C3 is connected to one end of the primary winding of the transformer. The other end of the primary winding of the transformer is connected between the first input capacitor C1 and the second input capacitor C2. The source of the second switching transistor Q2 is connected to the input voltage U. 1N The negative electrode.

[0009] Preferably, the intermediate tap divides the secondary winding of the transformer into an upper secondary winding and a lower secondary winding, and the intermediate tap is the common terminal of the upper secondary winding and the lower secondary winding.

[0010] Using the above technical means, the intermediate tap divides the secondary winding of the transformer into an upper secondary winding and a lower secondary winding. Under low-voltage output conditions, the number of turns of the secondary winding can be reduced without increasing the cost.

[0011] Preferably, the rectifier unit includes a first rectifier diode D1 and a second rectifier diode D2, and the secondary rectifier output filter unit includes a freewheeling diode D3, a freewheeling diode D4, an output filter inductor L1, an output filter inductor L2, and an output resistor R. L The output filter capacitor Co; the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 are connected in a common cathode configuration. The upper end of the secondary winding is connected to the anode of the first rectifier diode D1. The cathode of the first rectifier diode D1 is connected to the cathode of the freewheeling diode D3 and one end of the output filter inductor L1, respectively. The other end of the output filter inductor L1 is connected to the output resistor R. L One end of the output filter capacitor Co and one end of the output filter inductor L2, and the output resistor R L The other end of the output filter capacitor Co is connected to the anode of the freewheeling diode D3. The anode of the freewheeling diode D3 is connected to the lower end of the upper winding on the secondary side. The lower end of the upper winding on the secondary side is a center tap. The output resistance R LThe other end of the capacitor is connected to the other end of the output filter capacitor Co and then grounded.

[0012] The upper end of the secondary lower winding is connected to the anode of the freewheeling diode D4, and the upper end of the secondary lower winding is a center tap with an output resistance R. L The other end of the circuit and the other end of the output filter capacitor Co are also connected to the anode of the freewheeling diode D4. The lower end of the secondary side lower winding is connected to the anode of the second rectifier diode D2. The cathode of the second rectifier diode D2 is connected to the cathode of the freewheeling diode D4 and the other end of the output filter inductor L2, respectively.

[0013] Preferably, the rectifier unit includes a first rectifier diode D1 and a second rectifier diode D2, and the secondary rectifier output filter unit includes a freewheeling diode D3, a freewheeling diode D4, an output filter inductor L1, an output filter inductor L2, and an output resistor R. L The output filter capacitor Co; the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 are connected in a common anode configuration. The upper end of the secondary winding is connected to the cathode of the second rectifier diode D2. The anode of the first rectifier diode D1 is connected to the anode of the freewheeling diode D4 and one end of the output filter inductor L2, respectively. The other end of the output filter inductor L2 is connected to the output resistor R. L One end of the output filter capacitor Co and one end of the output filter inductor L1, and the output resistor R L The other end of the output filter capacitor Co is connected to the cathode of the freewheeling diode D4. The cathode of the freewheeling diode D4 is connected to the lower end of the upper winding on the secondary side. The lower end of the upper winding on the secondary side is a center tap. The output resistance R L One end of the output filter capacitor Co is connected to the ground;

[0014] The upper end of the secondary lower winding is connected to the cathode of the freewheeling diode D3. The upper end of the secondary lower winding is a center tap, and the output resistance R is... L The other end of the circuit and the other end of the output filter capacitor Co are also connected to the cathode of the freewheeling diode D3. The lower end of the secondary side lower winding is connected to the cathode of the first rectifier diode D1. The anode of the first rectifier diode D1 is connected to the cathode of the freewheeling diode D3 and the other end of the output filter inductor L1, respectively.

[0015] Preferably, when the first switch Q1 is turned on and the second switch Q2 is turned off, the polarity of the induced voltage of the upper winding and the induced voltage of the lower winding on the secondary side are both: positive at the upper end and negative at the lower end. The first rectifier diode D1 and the freewheeling diode D4 are both turned on, while the second rectifier diode D2 and the freewheeling diode D3 are both turned off. The output filter inductor L1 stores energy, and the output filter inductor L2 releases energy. After the output filter inductor L2 has completely released energy, the freewheeling diode D4 is turned off and reverse-biased.

[0016] When the first switch Q1 is off and the second switch Q2 is on, the polarity of the induced voltage in the upper winding and the lower winding on the secondary side is positive at the lower end and negative at the upper end. The second rectifier diode D2 and the freewheeling diode D3 are both on, while the first rectifier diode D1 and the freewheeling diode D4 are both off. The output filter inductor L1 releases energy, while the output filter inductor L2 stores energy. After the output filter inductor L1 has completely released energy, the freewheeling diode D3 is turned off and reverse-biased.

[0017] When both the first switch Q1 and the second switch Q2 are turned off, the induced voltage of the upper winding on the secondary side and the induced voltage of the lower winding on the secondary side are both 0. Both the output filter inductor L1 and the output filter inductor L2 release energy, and both the freewheeling diode D3 and the freewheeling diode D4 are turned on at the same time.

[0018] Using the above technical means, with the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 connected in a common cathode configuration, and considering the conduction and cutoff states of the first switch Q1 and the second switch Q2, when the current multiplier rectifier circuit operates in a light no-load state, after the output filter inductor has completely released its energy, the freewheeling diode is cut off and reverse-biased, preventing reverse flow on the output filter inductor and avoiding the occurrence of current backflow.

[0019] Preferably, when the first switch Q1 is turned on and the second switch Q2 is turned off, the polarity of the induced voltage of the upper winding and the induced voltage of the lower winding on the secondary side are both: positive at the upper end and negative at the lower end. The first rectifier diode D1 and the freewheeling diode D4 are both turned on, while the second rectifier diode D2 and the freewheeling diode D3 are both turned off. The output filter inductor L1 stores energy, and the output filter inductor L2 releases energy. After the output filter inductor L2 has completely released energy, the freewheeling diode D4 is turned off and reverse-biased.

[0020] When the first switch Q1 is off and the second switch Q2 is on, the polarity of the induced voltage in the upper winding and the lower winding on the secondary side is positive at the lower end and negative at the upper end. The second rectifier diode D2 and the freewheeling diode D3 are both on, while the first rectifier diode D1 and the freewheeling diode D4 are both off. The output filter inductor L1 releases energy, while the output filter inductor L2 stores energy. After the output filter inductor L1 has completely released energy, the freewheeling diode D3 is turned off and reverse-biased.

[0021] When both the first switch Q1 and the second switch Q2 are turned off, the induced voltage of the upper winding on the secondary side and the induced voltage of the lower winding on the secondary side are both 0. Both the output filter inductor L1 and the output filter inductor L2 release energy, and both the freewheeling diode D3 and the freewheeling diode D4 are turned on at the same time.

[0022] Using the above technical means, with the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 connected in a common anode configuration, and considering the conduction and cutoff states of the first switch Q1 and the second switch Q2, when the current multiplier rectifier circuit operates in a light no-load state, after the output filter inductor has completely released its energy, the freewheeling diode is cut off and reverse-biased, preventing reverse flow on the output filter inductor and avoiding the occurrence of current backflow.

[0023] Preferably, the first rectifier diode D1 and the second rectifier diode D2 are replaced with an N-channel power MOSFET with low on-resistance to reduce the loss of the current multiplier rectifier circuit.

[0024] Secondly, the present invention proposes a DC converter, which includes the current multiplier rectifier circuit suitable for light no-load operation.

[0025] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0026] This invention proposes a current-doubling rectifier circuit and DC-DC converter suitable for light no-load operation. A rectifier unit is added to the secondary rectifier circuit to cooperate with the energy release of the secondary rectifier output filter unit, prevent the reverse flow of current in the secondary rectifier output filter unit, and avoid current backflow. Attached Figure Description

[0027] Figure 1 This diagram illustrates the structure of a current multiplier rectifier circuit using a common cathode diode connection, as presented in the background section of this invention.

[0028] Figure 2 This diagram illustrates the structure of a current multiplier rectifier circuit using a common anode diode connection, as presented in the background section of this invention.

[0029] Figure 3This diagram shows the overall structure of the current-doubling rectifier circuit proposed in this embodiment of the invention, which is suitable for light no-load operation.

[0030] Figure 4 This diagram illustrates the structure of a current-doubling rectifier circuit suitable for light no-load operation when the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 proposed in this embodiment of the invention are connected in a common cathode configuration.

[0031] Figure 5 This diagram illustrates the current flow in the secondary rectifier circuit when the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 proposed in this embodiment of the invention are connected in a common cathode configuration, and when the first switch Q1 is turned on and the second switch Q2 is turned off.

[0032] Figure 6 This diagram illustrates the current flow in the secondary rectifier circuit when the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 proposed in this embodiment of the invention are connected in a common cathode configuration, and when the first switch Q1 is off and the second switch Q2 is on.

[0033] Figure 7 This diagram illustrates the current flow in the secondary rectifier circuit when the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 proposed in this embodiment of the invention are connected in a common cathode configuration, and when the first switch Q1 is turned off and the second switch Q2 is turned off.

[0034] Figure 8 This diagram illustrates the structure of a current-doubling rectifier circuit suitable for light no-load operation when the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 proposed in this embodiment of the invention are connected in a common anode configuration.

[0035] Figure 9 This diagram illustrates a current-doubling rectifier circuit structure suitable for light no-load operation, formed when the freewheeling diodes D3 and D4 in this embodiment of the invention are connected in a common cathode configuration and the first rectifier diode D1 and the second rectifier diode D2 are replaced with an N-channel power MOSFET with low on-resistance.

[0036] Figure 10 This diagram illustrates a current-doubling rectifier circuit structure suitable for light no-load operation, formed when the freewheeling diodes D3 and D4 in the embodiments of the present invention are connected in a common anode configuration and the first rectifier diode D1 and the second rectifier diode D2 are replaced by an N-channel power MOSFET with low on-resistance.

[0037] Among them, 1-primary side bridge circuit; 2-transformer; 3-secondary rectifier circuit; 4-intermediate tap; 31-rectifier unit;

[0038] 32-Rectifier Output Filter Unit Detailed Implementation

[0039] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention.

[0040] To better illustrate this embodiment, some parts of the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions;

[0041] It is understandable to those skilled in the art that some well-known details may be omitted from the accompanying drawings.

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments;

[0043] The positional relationships depicted in the accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention.

[0044] Example 1

[0045] like Figure 3 As shown, this embodiment proposes a current-doubling rectifier circuit suitable for light no-load operating conditions. See [link to relevant documentation]. Figure 3 The system includes: a primary-side bridge circuit 1, a transformer 2, and a secondary rectifier circuit 3. The output of the primary-side bridge circuit 1 is connected to the primary winding of the transformer 2. The secondary rectifier circuit 3 includes a rectifier unit 31 and a secondary rectifier output filter unit 32. The secondary winding of the transformer is sequentially connected to the rectifier unit 31 and the secondary rectifier output filter unit 32. A center tap 4 is provided on the secondary winding of the transformer 2, serving as a lead-out terminal of the secondary winding and connected to the secondary rectifier output filter unit 32. The topology of the primary-side bridge circuit 1 can be a hard-switching full-bridge DC-DC converter circuit, a soft-switching full-bridge phase-shifted DC-DC converter circuit, or an asymmetric half-bridge DC-DC converter circuit.

[0046] In this embodiment, see Figure 3 The primary-side bridge circuit 1 includes: a first input capacitor C1, a second input capacitor C2, a first switching transistor Q1, a second switching transistor Q2, a third input capacitor C3, and an input voltage U. 1N The positive terminals of the capacitors are connected to one end of the first input capacitor C1 and the drain of the first switching transistor Q1, respectively. The other end of the first input capacitor C1 is connected to one end of the second input capacitor C2, and the other end of the second input capacitor C2 is connected to the input voltage U. 1NThe negative terminal of the first switching transistor Q1 is connected to one end of the third input capacitor C3 and the drain of the second switching transistor Q2. The other end of the third input capacitor C3 is connected to one end of the primary winding of the transformer 2. The other end of the primary winding of the transformer 2 is connected between the first input capacitor C1 and the second input capacitor C2. The source of the second switching transistor Q2 is connected to the input voltage U. 1N The negative electrode.

[0047] The center tap 4 divides the secondary winding of the transformer into an upper secondary winding and a lower secondary winding. The center tap 4 is the common terminal of the upper secondary winding and the lower secondary winding. Under low voltage output conditions, the number of turns of the secondary winding can be reduced without increasing the cost.

[0048] like Figure 4 As shown, in this embodiment, the number of turns in the primary winding of the transformer is N. p The number of turns in the upper secondary winding and the lower secondary winding is represented by N. s It means, with Figure 1 and Figure 2 The circuit shown is the same as the traditional current doubler rectifier circuit, with an output voltage of U. o Transformer turns ratio Parameters are also related to Figure 1 and Figure 2 The design method for the output filter inductor is the same as that for a conventional current doubler rectifier circuit. (See also...) Figure 4 The right half shown includes a rectifier unit 31 comprising a first rectifier diode D1 and a second rectifier diode D2, and a secondary rectifier output filter unit 32 comprising a freewheeling diode D3, a freewheeling diode D4, an output filter inductor L1, an output filter inductor L2, and an output resistor R. L The output filter capacitor Co; the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 are connected in a common cathode configuration. The upper end of the secondary winding is connected to the anode of the first rectifier diode D1. The cathode of the first rectifier diode D1 is connected to the cathode of the freewheeling diode D3 and one end of the output filter inductor L1, respectively. The other end of the output filter inductor L1 is connected to the output resistor R. L One end of the output filter capacitor Co and one end of the output filter inductor L2, and the output resistor R L The other end of the output filter capacitor Co is connected to the anode of the freewheeling diode D3. The anode of the freewheeling diode D3 is connected to the lower end of the upper winding on the secondary side. The lower end of the upper winding on the secondary side is a center tap. The output resistance R L The other end of the capacitor is connected to the other end of the output filter capacitor Co and then grounded.

[0049] The upper end of the secondary lower winding is connected to the anode of the freewheeling diode D4. The upper end of the secondary lower winding is a center tap, and the output resistance R... L The other end of the circuit and the other end of the output filter capacitor Co are also connected to the anode of the freewheeling diode D4. The lower end of the secondary side lower winding is connected to the anode of the second rectifier diode D2. The cathode of the second rectifier diode D2 is connected to the cathode of the freewheeling diode D4 and the other end of the output filter inductor L2, respectively.

[0050] like Figure 5 As shown, when the first switch Q1 is on and the second switch Q2 is off, the polarities of the induced voltage in the upper winding and the lower winding on the secondary side are both positive at the upper end and negative at the lower end. The first rectifier diode D1 and the freewheeling diode D4 are both on (when the output filter inductor L2 has not yet fully released its stored energy), while the second rectifier diode D2 and the freewheeling diode D3 are both off. The output filter inductor L1 stores energy, and the polarity of its terminal voltage is positive on the left and negative on the right. The current i in the output filter inductor L1... L1 linearly increasing, in Figure 5 The current path in the middle is as follows Figure 5 As indicated by the arrows, the specific path is: secondary winding → anode of first rectifier diode D1 → cathode of first rectifier diode D1 → output filter inductor L1 → output filter capacitor Co → center tap. The output filter inductor L2 releases energy, with its terminal voltage polarity being positive on the right and negative on the left. The current i in the output filter inductor L2... L2 Linear decrease, in Figure 5 The current path in the middle is as follows Figure 5 As indicated by the arrow, the output filter inductor L2 leads to the output filter capacitor C. O → Anode of freewheeling diode D4 → Cathode of freewheeling diode D4 → Left end of output filter inductor L2 During this period, the current i of the first rectifier diode D1 D1 =i L1 =i NS When the current multiplier rectifier circuit operates under light no-load conditions, after the output filter inductor L2 has completely released its energy, the freewheeling diode D4 is turned off and reverse-biased, preventing the current on the output filter inductor L2 from flowing in reverse and avoiding the phenomenon of current backflow.

[0051] like Figure 6 As shown, when the first switch Q1 is off and the second switch Q2 is on, the polarities of the induced voltage in the upper winding and the lower winding on the secondary side are both: positive at the lower end and negative at the upper end. The second rectifier diode D2 and the freewheeling diode D3 are both on (when the output filter inductor L1 has not yet fully released its stored energy), while the first rectifier diode D1 and the freewheeling diode D4 are both off. The output filter inductor L1 releases energy, and the terminal voltage polarity is positive on the right and negative on the left. Its current i L1 Linear decrease, in Figure 6 The current path in the middle is as follows Figure 6 As indicated by the arrow, the output filter inductor L1 leads to the output filter capacitor C. O → Anode of freewheeling diode D3 → Cathode of freewheeling diode D3 → Left end of output filter inductor L1, while output filter inductor L2 stores energy, with the terminal voltage polarity being positive on the left and negative on the right, and its current i L2 linearly increasing, in Figure 6 The current path in the middle is as follows Figure 6 As indicated by the arrows, the specific path is: secondary winding → anode of second rectifier diode D2 → cathode of second rectifier diode D2 → output filter inductor L2 → output filter capacitor C. O → Center tap, during which the current i flowing through the second rectifier diode D2 is... D2 =i L2 =i NS After the output filter inductor L1 has fully released its energy, the freewheeling diode D3 is turned off and reverse-biased, preventing the current from flowing in reverse on the output filter inductor L1 and avoiding the phenomenon of current backflow.

[0052] like Figure 7 As shown, when both the first switch Q1 and the second switch Q2 are off, the induced voltage in the upper winding and the lower winding on the secondary side are both 0. Both output filter inductors L1 and L2 release energy, and both freewheeling diodes D3 and D4 are simultaneously turned on. The current flow direction can be seen in [reference needed]. Figure 7 The arrow shown points to...

[0053] Example 2

[0054] like Figure 8 As shown, in this embodiment, the number of turns in the primary winding of the transformer is N. p The number of turns in the upper secondary winding and the lower secondary winding is represented by N. s It means, with Figure 1 and Figure 2 The circuit shown is the same as the traditional current doubler rectifier circuit, with an output voltage of U. o Transformer turns ratio Parameters are also related to Figure 1 and Figure 2 The design method for the filter inductor is the same as that for a conventional current-doubling rectifier circuit. The rectifier unit 31 includes a first rectifier diode D1 and a second rectifier diode D2. The secondary rectifier output filter unit includes a freewheeling diode D3, a freewheeling diode D4, an output filter inductor L1, an output filter inductor L2, and an output resistor R. LThe output filter capacitor Co; the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 are connected in a common anode configuration. The upper end of the secondary winding is connected to the cathode of the second rectifier diode D2. The anode of the first rectifier diode D1 is connected to the anode of the freewheeling diode D4 and one end of the output filter inductor L2. The other end of the output filter inductor L2 is connected to the output resistor R. L One end of the output filter capacitor Co and one end of the output filter inductor L1, and the output resistor R L The other end of the output filter capacitor Co is connected to the cathode of the freewheeling diode D4. The cathode of the freewheeling diode D4 is connected to the lower end of the upper winding on the secondary side. The lower end of the upper winding on the secondary side is a center tap. The output resistance R L One end of the output filter capacitor Co is connected to the ground;

[0055] The upper end of the secondary lower winding is connected to the cathode of the freewheeling diode D3. The upper end of the secondary lower winding is a center tap, and the output resistance R is... L The other end of the circuit and the other end of the output filter capacitor Co are also connected to the cathode of the freewheeling diode D3. The lower end of the secondary side lower winding is connected to the cathode of the first rectifier diode D1. The anode of the first rectifier diode D1 is connected to the cathode of the freewheeling diode D3 and the other end of the output filter inductor L1, respectively.

[0056] The above describes a common anode connection for the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4. When the first rectifier diode D1, the second rectifier diode D2, the freewheeling diode D3, and the freewheeling diode D4 are connected in a common anode configuration, the situation is similar to that in Example 2.

[0057] When the first switch Q1 is turned on and the second switch Q2 is turned off, the polarity of the induced voltage in the upper winding and the lower winding on the secondary side is positive at the upper end and negative at the lower end. The first rectifier diode D1 and the freewheeling diode D4 are both turned on, while the second rectifier diode D2 and the freewheeling diode D3 are both turned off. The output filter inductor L1 stores energy, and the output filter inductor L2 releases energy. After the output filter inductor L2 has completely released energy, the freewheeling diode D4 is turned off and reverse-biased, preventing current from flowing back.

[0058] When the first switch Q1 is off and the second switch Q2 is on, the polarity of the induced voltage in the upper winding and the lower winding on the secondary side is positive at the lower end and negative at the upper end. The second rectifier diode D2 and the freewheeling diode D3 are both on, while the first rectifier diode D1 and the freewheeling diode D4 are both off. The output filter inductor L1 releases energy, while the output filter inductor L2 stores energy. After the output filter inductor L1 has completely released energy, the freewheeling diode D3 is turned off and reverse-biased, preventing current from flowing back.

[0059] When both the first switch Q1 and the second switch Q2 are turned off, the induced voltage of the upper winding on the secondary side and the induced voltage of the lower winding on the secondary side are both 0. Both the output filter inductor L1 and the output filter inductor L2 release energy, and both the freewheeling diode D3 and the freewheeling diode D4 are turned on at the same time.

[0060] Example 3

[0061] In this embodiment, the primary side bridge circuit 1, transformer 2, and secondary rectifier output filter unit 32 remain unchanged, such as Figure 9 As shown, the first rectifier diode D1 and the second rectifier diode D2 are replaced with N-channel power MOSFETs with low on-resistance to reduce the losses in the current multiplier rectifier circuit. For details, see [link to relevant documentation]. Figure 9 The low on-resistance N-channel power MOSFETs are QS1 and QS2, and in terms of their coordination, corresponding resistors R1 and R3, and resistors R2 and R4 are introduced and connected to the gate.

[0062] Example 4

[0063] This embodiment proposes a DC-DC converter, which includes the current-doubling rectifier circuit proposed in the previous embodiment that is suitable for light no-load operation. It has strong load adaptability and can be used for battery charging.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A current-doubling rectifier circuit suitable for light no-load operation, characterized in that, include: The system includes a primary-side bridge circuit, a transformer, and a secondary rectifier circuit. The output of the primary-side bridge circuit is connected to the primary winding of the transformer. The secondary rectifier circuit includes a rectifier unit and a secondary rectifier output filter unit. The secondary winding of the transformer is sequentially connected to the rectifier unit and the secondary rectifier output filter unit. The secondary winding of the transformer has an intermediate tap, which serves as a lead-out terminal of the secondary winding and is connected to the secondary rectifier output filter unit. The primary side-bridge circuit includes: a first input capacitor. C 1. Second input capacitor C 2. First switching transistor Q 1. Second switching transistor Q 2. Third input capacitor C 3. Input voltage U 1N The positive terminals are respectively connected to the first input capacitor. C One end of 1 and the first switching transistor Q 1's drain, first input capacitor C The other end of 1 is connected to the second input capacitor. C 2, one end, the second input capacitor C The other end of 2 is connected to the input voltage. U 1N The negative terminal; the first switching transistor Q The source of 1 is connected to the third input capacitor. C One end of 3 and the second switching transistor Q 2's drain, third input capacitor C The other end of 3 is connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the first input capacitor. C 1 and second input capacitors C Between 2, the second switching transistor Q 2's source is connected to the input voltage. U 1N The negative electrode; The intermediate tap divides the secondary winding of the transformer into an upper secondary winding and a lower secondary winding, and the intermediate tap is the common terminal of the upper secondary winding and the lower secondary winding. The rectifier unit includes a first rectifier diode. D 1 and second rectifier diodes D 2. The secondary rectifier output filter unit includes a freewheeling diode. D 3. Freewheeling diode D 4. Output filter inductor L 1. Output filter inductor L 2. Output resistance R L Output filter capacitor C o; First rectifier diode D 1. Second rectifier diode D 2. Freewheeling diode D 3. Freewheeling diode D 4 is a common cathode connection, and the upper end of the secondary winding is connected to the first rectifier diode. D The anode of 1, the first rectifier diode D The cathodes of 1 are connected to freewheeling diodes respectively. D 3 Cathode and output filter inductor L One end of 1 is the output filter inductor. L The other end of 1 is connected to the output resistor. R L One end, output filter capacitor C One end of o and the output filter inductor L One end of 2, output resistor R L The other end, output filter capacitor C The other end of o is connected to a freewheeling diode. D 3's anode, freewheeling diode D The anode of 3 is connected to the lower end of the upper secondary winding. The lower end of the upper secondary winding is a center tap, and the output resistance is... R L The other end, output filter capacitor C The other end of o is connected to ground; The upper end of the secondary side lower winding is connected to a freewheeling diode. D The anode of 4 has a center tap at the top of the lower secondary winding, and the output resistance is... R L The other end, output filter capacitor C The other end of o is also connected to a freewheeling diode. D The anode of 4, the lower end of the secondary side lower winding is connected to the second rectifier diode. D 2's anode, the second rectifier diode D The cathodes of 2 are respectively connected to freewheeling diodes. D 4 Cathode and output filter inductor L The other end of 2.

2. The current-doubling rectifier circuit suitable for light no-load operation as described in claim 1, characterized in that, The primary-side bridge circuit is a hard-switching full-bridge DC-DC converter circuit, a soft-switching full-bridge phase-shift DC-DC converter circuit, or an asymmetric half-bridge DC-DC converter circuit.

3. The current-doubling rectifier circuit suitable for light no-load operation as described in claim 1, characterized in that, The rectifier unit includes a first rectifier diode. D 1 and second rectifier diodes D 2. The secondary rectifier output filter unit includes a freewheeling diode. D 3. Freewheeling diode D 4. Output filter inductor L 1. Output filter inductor L 2. Output resistance R L Output filter capacitor C o; First rectifier diode D 1. Second rectifier diode D 2. Freewheeling diode D 3. Freewheeling diode D 4 is a common anode connection, and the upper end of the secondary winding is connected to the second rectifier diode. D Cathode of 2, first rectifier diode D The anodes of 1 are respectively connected to freewheeling diodes. D 4's anode and output filter inductor L One end of 2 is the output filter inductor. L The other end of 2 is connected to the output resistor. R L One end, output filter capacitor C One end of o and the output filter inductor L One end of 1, output resistor R L The other end, output filter capacitor C The other end of o is connected to a freewheeling diode. D 4 cathode, freewheeling diode D The cathode of 4 is connected to the lower end of the upper secondary winding. The lower end of the upper secondary winding is a center tap, and the output resistance is... R L One end, output filter capacitor C One end of o is connected to ground; The upper end of the secondary side lower winding is connected to a freewheeling diode. D The cathode of the 3rd generation secondary winding has a center tap at the top, and the output resistance is... R L The other end, output filter capacitor C The other end of o is also connected to a freewheeling diode. D The cathode of 3, the lower end of the secondary side lower winding is connected to the first rectifier diode. D Cathode of 1, first rectifier diode D The anodes of 1 are respectively connected to freewheeling diodes. D 3 Cathode and output filter inductor L The other end of 1.

4. The current-doubling rectifier circuit suitable for light no-load operation as described in claim 1, characterized in that, First switching transistor Q 1. On, second switching transistor Q When cut off, the polarity of the induced voltage in the upper secondary winding and the induced voltage in the lower secondary winding are both: positive at the upper end and negative at the lower end. The first rectifier diode... D 1 and freewheeling diode D All four diodes are conducting, while the second rectifier diode is conducting. D 2 and freewheeling diode D All 3 are cut off, output filter inductor L 1. Energy storage and output filter inductor L 2. Release energy in the output filter inductor. L 2. After the energy is fully released, the freewheeling diode D 4. Cutoff bias; First switching transistor Q 1. Cut-off, second switching transistor Q When the second rectifier diode is turned on, the polarity of the induced voltage in the upper winding and the lower winding on the secondary side is: positive at the lower end and negative at the upper end. D 2 and freewheeling diode D All three diodes are conducting, while the first rectifier diode is conducting. D 1 and freewheeling diode D All 4 are cut off, output filter inductor L 1. Release energy, while the output filter inductor L 2. Store energy in the output filter inductor. L 1. After the energy is fully released, the freewheeling diode D 3. Cutoff bias; First switching transistor Q 1. Second switching transistor Q When both are cut off, the induced voltage in the upper secondary winding and the induced voltage in the lower secondary winding are both 0, and the output filter inductor... L 1 and output filter inductor L Both release energy, freewheeling diode D 3 and freewheeling diode D 4. All are conducting simultaneously.

5. The current-doubling rectifier circuit suitable for light no-load operation as described in claim 3, characterized in that, First switching transistor Q 1. On, second switching transistor Q When cut off, the polarity of the induced voltage in the upper secondary winding and the induced voltage in the lower secondary winding are both: positive at the upper end and negative at the lower end. The first rectifier diode... D 1 and freewheeling diode D All four diodes are conducting, while the second rectifier diode is conducting. D 2 and freewheeling diode D All 3 are cut off, output filter inductor L 1. Energy storage and output filter inductor L 2. Release energy in the output filter inductor. L 2. After the energy is fully released, the freewheeling diode D 4. Cutoff bias; First switching transistor Q 1. Cut-off, second switching transistor Q When the second rectifier diode is turned on, the polarity of the induced voltage in the upper winding and the lower winding on the secondary side is: positive at the lower end and negative at the upper end. D 2 and freewheeling diode D All three diodes are conducting, while the first rectifier diode is conducting. D 1 and freewheeling diode D All 4 are cut off, output filter inductor L 1. Release energy, while the output filter inductor L 2. Store energy in the output filter inductor. L 1. After the energy is fully released, the freewheeling diode D 3. Cutoff bias; First switching transistor Q 1. Second switching transistor Q When both are cut off, the induced voltage in the upper secondary winding and the induced voltage in the lower secondary winding are both 0, and the output filter inductor... L 1 and output filter inductor L Both release energy, freewheeling diode D 3 and freewheeling diode D 4. All are conducting simultaneously.

6. The current-doubling rectifier circuit suitable for light no-load operation as described in claim 2 or 3, characterized in that, Replace the first rectifier diode with an N-channel power MOSFET with low on-resistance. D 1 and second rectifier diodes D 2.

7. A DC-DC converter, characterized in that, The DC-DC converter includes the current-doubling rectifier circuit suitable for light no-load operation as described in any one of claims 1 to 6.

Images