Resonant conversion circuit

Abstract

A resonant conversion circuit disclosed by the present invention comprises a resonant branch, a switch unit and a rectification unit, an input power supply is connected to an input port of the switch unit to supply power to the resonant conversion circuit, the switch unit, the resonant branch and the rectification unit are connected in parallel, and an output end of the rectification unit is connected with a load. The resonant conversion circuit further comprises a resonant current detection module, the input end of the resonant current detection module is connected with the resonant branch, the resonant current detection module is used for detecting resonant current in the resonant branch, and the resonant current detection module outputs first voltage. And the excitation current detection module is used for detecting excitation current in the resonance branch, the excitation current detection module outputs second voltage, and the output end of the excitation current detection module is connected with the output end of the resonance current detection circuit in parallel and outputs third voltage. According to the invention, no extra loss is caused, the number of required peripheral devices is small, and the efficiency and the power density of the system can be improved; and the post-stage rectification circuit can be used for current reporting and zero crossing point detection.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy conversion, and in particular to a resonant conversion circuit. Background Art

[0002] As the functions and performance of electronic devices continue to improve, the requirements for power supply equipment are also getting higher and higher, including high power density, high efficiency, high dynamics, and high reliability. In order to meet these requirements, a control method with high dynamic characteristics needs to be adopted when designing the power supply. To this end, a current signal needs to be added to the power supply module as an input signal for the control circuit and the protection circuit to control the power supply and make the circuit work more stable and reliable. In order to use the current signal in the circuit for control, the current needs to be sampled.

[0003] For the resonant circuit, it is very important to control the resonant current in the sampling circuit for the operation of the entire circuit. In some applications, the current sampling signal is also needed for load current reporting and zero-crossing detection. Therefore, it is necessary to sample the excitation current while sampling the resonant current, and weight the two to obtain the secondary winding current signal, i.e., the load signal. Summary of the invention

[0004] To achieve the above purpose, the technical solution of the present invention is:

[0005] A resonant conversion circuit comprises a resonant branch, a switch unit and a rectifier unit, wherein an input power source is connected to an input port of the switch unit to power the resonant conversion circuit, the switch unit, the resonant branch and the rectifier unit are connected in parallel, and an output end of the rectifier unit is connected to a load, and the resonant conversion circuit further comprises: a resonant current detection module, wherein an input end of the resonant current detection module is connected to the resonant branch for detecting a resonant current in the resonant branch, and the resonant current detection module outputs a first voltage;

[0006] An excitation current detection module, the excitation current detection module is used to detect the excitation current in the resonant branch, the excitation current detection module outputs a second voltage, the output end of the excitation current detection circuit is connected in parallel with the output end of the resonant current detection circuit and outputs a third voltage;

[0007] The excitation current detection module is controlled by a driving signal of the switch unit.

[0008] In a specific embodiment of the present invention, the resonant branch includes a resonant capacitor, a first end of the resonant capacitor is connected to the first output end of the switch unit, and an input end of the resonant current detection module is connected to the second end of the resonant capacitor.

[0009] a resonant inductor, wherein a first end of the resonant inductor is connected to a second end of the resonant capacitor,

[0010] A main transformer, wherein the first end of the primary side winding of the main transformer is connected to the second end of the resonant inductor, the second end of the primary side winding of the main transformer is connected to the second output end of the switch unit, the first end of the first secondary side winding of the main transformer is connected to the first input end of the rectifier unit, the second end of the first secondary side winding of the main transformer is connected to the first end of the second secondary side winding of the main transformer, and the second end of the second secondary side winding of the main transformer is connected to the second input end of the rectifier unit.

[0011] In a specific embodiment, the excitation current detection module includes a third winding, a third resistor and a third capacitor, the first end of the third winding is connected to the second end of the primary side winding of the main transformer, the first end of the third resistor is connected to the second end of the third winding, the first end of the third capacitor is connected to the second end of the third resistor, the second end of the third capacitor is grounded, and the connection point between the third capacitor and the third resistor outputs the second voltage; the excitation current detection module also includes a sub-transformer, the third winding is the secondary side winding of the sub-transformer, and the driving signal of the switch unit is input at both ends of the primary side winding of the sub-transformer.

[0012] In a specific embodiment, the excitation current detection module includes a third winding, a third resistor and a third capacitor, the first end of the third winding is connected to the first end of the third resistor, the second end of the third resistor is connected to the first end of the third capacitor, the second end of the third capacitor is connected to the second end of the third winding, the voltage across the third capacitor is the second voltage, and the connection point between the third capacitor and the third resistor outputs the third voltage; the excitation current detection module also includes a sub-transformer, the third winding is the secondary side winding of the sub-transformer, and the driving signal of the switch module is input at both ends of the primary side winding of the sub-transformer.

[0013] In a specific embodiment, the excitation current detection module includes multiple current sources and a sixth capacitor, one end of the sixth capacitor is connected to the common end of the multiple current sources, and the sixth capacitor is connected to the output end of the resonant current detection module; the driving signal of the switching unit controls the current source and is proportional to the output current of the current source.

[0014] In a specific embodiment, the above-mentioned resonant current detection module includes a first operational amplifier, a first capacitor, a second capacitor, a first resistor and a second resistor. The first end of the resonant capacitor is connected to the positive input end of the first operational amplifier through the second capacitor, the second end of the resonant capacitor is connected to the negative input end of the first operational amplifier through the first capacitor, the positive input end of the first operational amplifier is grounded through the second resistor, the negative input end of the first operational amplifier is connected to the output end of the first operational amplifier through the first resistor, and the output end of the first operational amplifier outputs the first voltage.

[0015] In a specific embodiment, the resonant current detection module further includes a fourth resistor and a fifth resistor, and the second end of the third resistor or the sixth capacitor and the common end of the plurality of current sources are connected to the output end of the first operational amplifier via the fourth resistor and the fifth resistor.

[0016] In a specific embodiment, the above-mentioned resonant current detection module also includes a second operational amplifier, a sixth resistor and a seventh resistor, the positive input terminal of the second operational amplifier is connected to the connection point of the fourth resistor and the fifth resistor, the negative input terminal of the second operational amplifier is grounded through the sixth resistor, and the negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through the seventh resistor.

[0017] Beneficial effects: The present invention provides a resonant conversion circuit, which obtains the resonant current by sampling the voltage on the resonant capacitor, and obtains the excitation current by an external winding and an integration module composed of a capacitor and a resistor, without causing additional losses. Fewer peripheral devices are required, which helps to improve the efficiency and power density of the system; a differential sampling method is adopted to reduce the influence of switching noise on the sampling signal, which is beneficial to current control and rapid protection; the resonant current and the excitation current are weighted to obtain a secondary side winding current signal, that is, a load current signal, which is connected to a rectifier circuit at the later stage and can be used for current reporting and zero-crossing detection; this current detection method of subtracting the excitation current can obtain a more accurate resonant current, which can be used for more accurate current control and protection.

[0018] In order to make the above features and advantages of the invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a structural block diagram of a resonant conversion circuit of the present invention.

[0020] Figure 2 This is the first specific embodiment of a resonant conversion circuit of the present invention.

[0021] Figure 3This is a second specific embodiment of a resonant conversion circuit of the present invention.

[0022] Figure 4 This is a third specific embodiment of a resonant conversion circuit of the present invention.

[0023] Figure 5 This is a fourth specific embodiment of a resonant conversion circuit of the present invention.

[0024] Figure 6 This is the fifth specific embodiment of a resonant conversion circuit of the present invention.

[0025] Figure 7 This is the sixth specific embodiment of a resonant conversion circuit of the present invention.

[0026] Figure 8 This is the seventh specific embodiment of a resonant conversion circuit of the present invention.

[0027] Fig. 9 This is the eighth specific embodiment of a resonant conversion circuit of the present invention.

[0028] Fig.10 This is a ninth specific embodiment of a resonant conversion circuit of the present invention.

[0029] Fig.11 This is the tenth specific embodiment of a resonant conversion circuit of the present invention.

[0030] Fig.12 for Figure 2 Simulation waveform diagram of the working process of the resonance module.

[0031] Fig.13 for Fig.11 Simulation waveform diagram of the working process of the resonance module.

[0032] Description of the accompanying drawings:

[0033] 101, 201, 301, 401, 501, 601, 701, 801, 901, 1001, 1101-resonance module; 1011, 2011, 3011, 4011, 5011, 6011, 7011, 8011, 9011, 10011, 11011-resonance branch; 1012, 2012, 3012, 4012, 5012, 6012, 7012, 8012, 9012, 10012, 11012-switch unit Element; 1013, 2013, 3013, 4013, 5013, 6013, 7013, 8013, 9013, 10013, 11013 - rectifier unit; 102, 202, 302, 402, 502, 602, 702, 802, 902, 1002, 1102 - resonant current detection module; 103, 203, 303, 403, 503, 603, 703, 803, 903, 1003, 1103 - excitation current detection module. DETAILED DESCRIPTION

[0034] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1 The structure block diagram of a resonant conversion circuit of the present invention is shown, which includes a resonant module 101, a resonant current detection module 102 and an excitation current detection module 103. The input power supply V in The resonant module 101 is powered, the output end of the resonant module 101 is connected to a load, and the input end of the resonant current detection module 102 is connected to the resonant module 101 to detect the resonant current i in the resonant module 101. Lr The resonant current detection module 102 outputs a voltage v cs1 The excitation current detection module 103 is used to detect the excitation current i in the resonance module 101. Lm The excitation current detection module 103 outputs a voltage v cs2 The output end of the excitation current detection module 103 is connected in parallel with the output end of the resonant current detection module 102 and outputs a voltage v sy The resonant current i Lr and the excitation current i Lm The secondary winding current signal, namely the load current signal, is obtained by weighting, and the signal can be used for current reporting and zero-crossing point detection.

[0036] Furthermore, the input power supply V in is a DC voltage source.

[0037] Further, the resonance module 101 includes a resonance branch 1011, a switch unit 1012 and a rectification unit 1013, the resonance branch 1011, the switch unit 1012 and the rectification unit 1013 are connected in parallel, and an input end of the resonance current detection module 102 is connected to the resonance branch 1011. The switch unit 1012 is, for example, a full-bridge or half-bridge module, and the rectification unit 1013 is, for example, a full-wave rectification unit or a half-wave rectification unit, and the rectification mode is not limited to synchronous rectification or asynchronous rectification.

[0038] More specifically, the resonant branch 1011 includes a capacitor C r 、Inductance L r and transformer T r , the capacitor C r The first end of the resonant current detection module 102 is connected to the first output end of the switch unit 1012, and the first input end of the resonant current detection module 102 is connected to the capacitor C r The second end of the inductor L r One end of the capacitor C r The second end of the inductor L r The other end of the transformer T r The primary winding N p The first end of the primary winding N p The second end of the transformer T is connected to the second output end of the switch unit 1012. r The excitation inductance L m The equivalent parallel connection in the primary winding N p Both ends of the transformer T r The secondary winding N s The first end of the secondary winding N is connected to the first input end of the rectifier unit 1013. s The second end of is connected to the second input end of the rectifying unit 1013.

[0039] like Figure 2 FIG. 1 is a first specific embodiment of a resonant conversion circuit according to the present invention. Figure 1 On the basis of the circuit, a specific structure of a switch unit 2012, a rectifier unit 2013, a resonant current detection module 202 and an excitation current detection module 203 is provided.

[0040] The switch unit 2012 includes a switch Q1 and a switch Q2. The source of the switch Q1 is connected to the drain of the switch Q2. The drain of the switch Q1 is connected to the input power source Vin The positive electrode of the switch Q2 is connected to the input power supply V in The negative terminal of the input power supply V in The negative electrode of the switch Q1 is connected to the ground, and the source of the switch Q1 is connected to the capacitor C r The first end.

[0041] The rectifying unit 2013 includes a diode D1 and a diode D2. The anode of the diode D1 is connected to the transformer T r The secondary winding N s1 The first end of the secondary winding N s1 The second end of the transformer T r The secondary winding N s2 The first end of the secondary winding N s2 The second end of the diode D2 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the cathode of the diode D1, and the cathode of the diode D1 is connected to the secondary winding N s1 The second end of the parallel capacitor C o , the capacitor C o The parallel resistor R o , the resistor R o The voltage across the terminals is the output voltage V o .

[0042] Furthermore, the transformer T r The transformation ratio is N.

[0043] More specifically, the primary winding N p The number of turns is N1, the secondary winding N s1 and the secondary winding N s2 The number of turns is N2.

[0044] The resonant current detection module 202 includes an operational amplifier A1, a capacitor C1, a capacitor C2, a resistor R1 and a resistor R2. r The first end of the operational amplifier A1 is connected to the positive input terminal of the operational amplifier A1 through the capacitor C2. r The second end of the resistor R2 is connected to the negative input terminal of the operational amplifier A1 through the capacitor C1, the first end of the resistor R2 is grounded, the second end of the resistor R2 is connected to the positive input terminal of the operational amplifier A1, the first end of the resistor R1 is connected to the negative input terminal of the operational amplifier A1, the second end of the resistor R1 is connected to the output terminal of the operational amplifier A1, and the output terminal of the operational amplifier A1 outputs the voltage v cs1 .

[0045] Furthermore, diode D1, diode D2, capacitor C oForm a rectifier and filter network.

[0046] Furthermore, the values ​​of the resistor R1 and the resistor R2 are equal to R s , the values ​​of the capacitor C1 and the capacitor C2 are equal to C s .

[0047] The capacitor C r Neither end of the capacitor C is grounded. r The voltage at both ends is sampled differentially and used as the input of the operational amplifier A1 in the form of a differential. The voltage v can be obtained according to the virtual short and virtual open of the operational amplifier A1. cs1 :

[0048]

[0049] Combining the above formulas, we can get:

[0050]

[0051] Right now,

[0052]

[0053] Among them, v cr+ The capacitance C r Positive terminal voltage, v cr- The capacitance C r Negative terminal voltage, v + is the voltage at the positive input terminal of the operational amplifier A1, v - is the voltage at the negative input terminal of the operational amplifier A1, v cr The capacitance C r The voltage at both ends, as can be seen from the above formula, the voltage v cs1 With the resonant current i Lr Ratio R s C s / C r .

[0054] The excitation current detection module 203 includes a winding N s3 , resistor R3 and capacitor C3, the winding N s3 The transformer T is coupled to r On the primary side, the winding N s3 The first end is connected to the primary winding N p The second end of the resistor R3 is connected to the winding N s3The first end of the capacitor C3 is connected to the second end of the resistor R3, the second end of the capacitor C3 is grounded, the second end of the resistor R3 is connected to the output end of the operational amplifier A1 through the resistor R4 and the resistor R5, and the connection point between the capacitor C3 and the resistor R3 outputs the voltage v cs2 The output voltage v at the connection point of the resistor R4 and the resistor R5 is sy1 .

[0055] Furthermore, the winding N s3 The number of turns is N3.

[0056] In this embodiment, the working principle of the resonant conversion circuit is as follows: a complete switching cycle T s The switch Q1 and the switch Q2 are alternately turned on during the period. When only the switch Q1 is turned on, half of the switching period T is experienced. s , the resonant module 201 works in the positive half cycle, the diode D1 is forward-conducted, and the output voltage V o Through the transformer T r Added to the magnetizing inductance L m Both ends of the excitation inductance L m The voltage across the terminals is clamped to N*V o When the switch Q2 is turned on, the negative half cycle of the resonant module 201 works, the diode D2 is forward-conducted, and the output voltage V o Through the transformer T r Added to the magnetizing inductance L m Both ends of the excitation inductance L m The voltage across the terminals is clamped to -N*V o , it can be seen that the excitation current i Lm With the transformer T r The voltage relationship is:

[0057]

[0058] In the excitation current detection module 203, the resistor R3 and the capacitor C3 are connected in series to form an integration module, and the voltage across the winding N3 is the input voltage of the integration module. cs2 is the output voltage of the integration module, and the relevant formula is as follows:

[0059]

[0060] From the above two formulas, it can be seen that the voltage v cs2 With the excitation current i Lm The relationship is as follows:

[0061]

[0062] Since the voltage v sy1 The voltage v cs1 and the voltage v cs2 The voltage v sy1 With the excitation current i Lm And the resonant current i Lr The relationship is as follows:

[0063]

[0064] When appropriate parameters are selected, When:

[0065]

[0066] Among them, i o is the load current. As can be seen from the above formula, the voltage v sy1 With the load current i o Ratio R s C s / C r .

[0067] Fig.12 for Figure 2 The working process simulation waveform diagram of the resonance module 201, wherein V gs1 is the driving signal of the switch Q1, V gs2 is the driving signal of the switch Q2, i Lr is the resonant current, i Lm is the excitation current, i o is the load current, v ys1 is the load current i o The corresponding sampling signal. As can be seen from the figure, the load current i o The corresponding sampling signal v ys1 Can follow the load current i o Changes in the same proportion.

[0068] In summary, Figure 2 The resonant converter circuit in the embodiment samples the capacitor C through a differential circuit. r The voltage on the resonant current i is obtained Lr , by adding the winding N s3 And the integration module obtains the excitation current i Lm , will not bring additional losses, fewer peripheral devices are required, which helps to improve the efficiency and power density of the system; the differential sampling method is adopted to reduce the influence of switching noise on the sampling signal, which is beneficial to current control and rapid protection; the resonant current i Lr and the excitation current iLm The secondary winding current signal is obtained by weighting, that is, the load current i o The signal is connected to a rectifier circuit at the rear stage and can be used for current reporting and zero-crossing detection. This current sampling method of subtracting the excitation current can obtain a more accurate resonant current signal, which can be used for more accurate current control and protection.

[0069] like Figure 3 FIG. 2 is a second specific embodiment of a resonant conversion circuit according to the present invention. Figure 2 On the basis of the circuit in FIG. 1 , a common-phase proportional amplifier circuit composed of an operational amplifier A2, a resistor R6 and a resistor R7 is added. The positive input terminal of the operational amplifier A2 is connected to the connection point of the resistor R4 and the resistor R5. The negative input terminal of the operational amplifier A2 is connected to the first end of the resistor R2 through the resistor R6. The first end of the resistor R7 is connected to the negative input terminal of the operational amplifier A2. The second end of the resistor R7 is connected to the output terminal of the operational amplifier A2. The output terminal of the operational amplifier A2 outputs a voltage v sy2 In this embodiment, the resistance values ​​of the resistor R4 and the resistor R5 are equal.

[0070] According to the properties of the same-direction proportional amplifier circuit, we can get:

[0071]

[0072] It can be seen from the above formula that the voltage v sy2 With the load current i o Ratio (1+R7 / R6)R s C s / C r .

[0073] like Figure 4 FIG. 1 is a third specific embodiment of a resonant conversion circuit according to the present invention. Figure 2 Based on the circuit, another specific structure of the excitation current detection module 403 is provided, including a winding N s3 , resistor R3 and capacitor C3, the winding N s3 The transformer T is coupled to r On the primary side, the winding N s3 The first end of the first end of the resistor R3 is connected to the first end of the capacitor C3, and the second end of the capacitor C3 is connected to the winding N s3 The second end of the capacitor C3 is connected to the output end of the operational amplifier A1, and the voltage across the capacitor C3 is the voltage v cs2 The output voltage v at the connection point of the capacitor C3 and the resistor R3 is sy3 .

[0074] In this embodiment, the working principle of the resonant conversion circuit is the same as Figure 2 The same, we can get:

[0075]

[0076] It can be seen from the above formula that the voltage v sy3 With the load current i o Ratio R s C s / C r .

[0077] Figures 2 to 4 All of them are through the main transformer, that is, the transformer T r The winding N is added s3 And the integration module obtains the excitation current i Lm , the winding N s3 The transformer T in the resonant circuit r The windings are coupled together, which will increase the transformer T r The window area. Figure 5 FIG. 4 is a fourth specific embodiment of a resonant conversion circuit according to the present invention. Figure 2 Based on the circuit, another specific structure of the excitation current detection module 503 is provided, including a transformer T r1 , resistor R8 and capacitor C4, the transformer T r1 The secondary winding N f4 The first end is connected to the primary winding N p The second end of the resistor R8 is connected to the secondary winding N f4 The first end of the capacitor C4 is connected to the second end of the resistor R8, the second end of the capacitor C4 is grounded, the second end of the resistor R8 is connected to the output end of the operational amplifier A1 through the resistor R4 and the resistor R5, and the connection point between the capacitor C4 and the resistor R8 outputs the voltage v cs2 The output voltage v at the connection point of the resistor R4 and the resistor R5 is sy4 , the transformer T r1 The primary winding N f5 The first end of the switch Q2 receives the drive signal V gs2 , the transformer T r1 The primary winding N f5 The second end of the switch Q1 is input with the driving signal V gs1 .

[0078] Furthermore, the secondary winding N f4 The number of turns is N4, the primary winding Nf5 The number of turns is N5.

[0079] In the excitation current detection module 503, the resistor R8 and the capacitor C4 are connected in series to form an integration module, and the winding N f4 The voltage across the two ends is the input voltage of the integration module. cs2 is the output voltage of the integration module, and the relevant formula is as follows:

[0080]

[0081] Among them, since the switch Q1 and the switch Q2 are complementary turned on, V gs is the driving signal V of the switch Q1 gs1 , then -V gs The drive signal V of the switch Q2 gs2 .

[0082] Depend on Figure 2 It is known that the excitation current i Lm With the transformer T r The voltage relationship is:

[0083]

[0084] From the above two formulas, it can be seen that the voltage v cs2 With the excitation current i Lm The relationship is as follows:

[0085]

[0086] Since the voltage v sy4 The voltage v cs1 and the voltage v cs2 The voltage v sy4 With the excitation current i Lm And the resonant current i Lr The relationship is as follows:

[0087]

[0088] When appropriate parameters are selected, When:

[0089]

[0090] It can be seen from the above formula that the voltage v sy4 With the load current i o Ratio R s C s / C r .

[0091] like Figure 6 FIG. 5 is a fifth specific embodiment of a resonant conversion circuit according to the present invention. Figure 5 On the basis of the circuit in FIG. 1 , a common-phase proportional amplifier circuit composed of an operational amplifier A2, a resistor R6 and a resistor R7 is added. The positive input terminal of the operational amplifier A2 is connected to the connection point of the resistor R4 and the resistor R5. The negative input terminal of the operational amplifier A2 is connected to the first end of the resistor R2 through the resistor R6. The first end of the resistor R7 is connected to the negative input terminal of the operational amplifier A2. The second end of the resistor R7 is connected to the output terminal of the operational amplifier A2. The output terminal of the operational amplifier A2 outputs a voltage v sy5 In this embodiment, the resistance values ​​of the resistor R4 and the resistor R5 are equal.

[0092] According to the properties of the same-direction proportional amplifier circuit, we can get:

[0093]

[0094] It can be seen from the above formula that the voltage v sy5 With the load current i o Ratio (1+R7 / R6)R s C s / C r .

[0095] like Figure 7 FIG. 6 is a sixth specific embodiment of a resonant conversion circuit according to the present invention. Figure 4 Based on the circuit, another specific structure of the excitation current detection module 703 is provided, including a transformer T r1 , resistor R8 and capacitor C4, the transformer T r1 The secondary winding N f4 The first end of the resistor R8 is connected to the first end of the resistor R8, the second end of the resistor R8 is connected to the first end of the capacitor C4, and the second end of the capacitor C4 is connected to the secondary winding N f4 The second end of the capacitor C4 is connected to the output end of the operational amplifier A1, and the voltage across the capacitor C4 is the voltage v cs2 The output voltage v at the connection point of the capacitor C4 and the resistor R8 is sy6 , the transformer T r1 The primary winding N f5 The first end of the switch Q1 receives the drive signal V gs1 , the transformer T r1 The primary winding N f5 The second end of the switch Q2 receives the drive signal V gs2 .

[0096] In this embodiment, the working principle of the resonant conversion circuit is the same as Figure 5 The same, we can get:

[0097]

[0098] It can be seen from the above formula that the voltage v sy6 With the load current i o Ratio R s C s / C r .

[0099] Compared to Figures 2 to 4 , Figures 5 to 7 The excitation current sampling winding is transformer T r1 The secondary winding N f4 , and the main transformer, that is, transformer T r The windings are separated and do not occupy the transformer T r The window area is small, which helps to miniaturize the design of magnetic components and improve power density. Figures 5 to 7 It can be seen from the embodiment that the excitation current sampling winding excitation voltage only needs to be equal to the output voltage V o The same phase can be generated to generate a constant current to charge and discharge the capacitor in the excitation current detection module in a complete cycle, thereby obtaining the same excitation current i Lm The capacitor voltage signal of the same proportion is the voltage v cs2 is the sampling signal, the specific circuit structure is as follows Figures 8 to 10 As shown, in Figures 2 to 4 Based on the circuit, another specific structure of the excitation current detection module is provided.

[0100] Figures 8 to 10 The excitation current detection module includes a current source CS1, a current source CS2 and a capacitor C6. The current source CS1 outputs a current I1, the current source CS2 outputs a current I2, one end of the capacitor C6 is connected to the midpoint of the series connection of the current source CS1 and the current source CS2, and the capacitor C6 is connected to the output end of the resonant current detection module. The drive signal V gs1 And the drive signal V of switch Q2 gs2 Control current source CS1 and current source CS2 respectively to meet the following conditions:

[0101] I1=KV gs1 ,

[0102] I2=KV gs2 ,

[0103] In the excitation current detection module, the voltage v cs2 The relationship with the switch drive signal is as follows:

[0104]

[0105] refer to Figure 5 From the derivation process, we can know that:

[0106]

[0107] When appropriate parameters are selected, When the sampling voltage is equal to the load current i o Ratio R s C s / C r . Where K is a coefficient.

[0108] Figures 2 to 10 Although the embodiment has lossless characteristics and accurate sampling, it introduces more peripheral devices, which is not conducive to improving power density. For further improvement, the resonant conversion circuit obtains the resonant current i Lr and the excitation current i Lm The load current i is obtained by using a two-current weighted method. o , the specific circuit structure is as follows Fig.11 shown.

[0109] Fig.11 This is a tenth specific embodiment of a resonant conversion circuit of the present invention. Figure 2 Based on the circuit in FIG. 1 , another specific structure of the resonant current detection module 1102 and the excitation current detection module 1103 is provided. In this embodiment, the voltage v output by the resonant current detection module 1102 is cs1 The positive input terminal of the input operational amplifier A3, the voltage v output by the excitation current detection module 1103 cs2 The negative input terminal of the operational amplifier A3 is input, and the output voltage of the operational amplifier A3 is v sy10 .

[0110] The resonant current detection module 1102 includes a resistor R9 and a resistor R 10 The first end of the resistor R9 is grounded, the second end of the resistor R9 is connected to the positive input end of the operational amplifier A3, and the resistor R 10 The first end of the resistor R9 is connected to the second end of the resistor R 10 The second end of the inductor L is connected r The first end of the resistor R 10 The connection point with the resistor R9 outputs the voltage v cs1 .

[0111] The excitation current detection module 1103 includes a winding N s6and capacitor C5, the winding N s6 The transformer T is coupled to r On the primary side, the winding N s6 The first end is connected to the primary winding N p The second end of the winding N s6 The second end of the capacitor C5 is connected to the negative input end of the operational amplifier A3, and the first end of the capacitor C5 is connected to the winding N s6 The second end of the capacitor C5 is connected to the second end of the resistor R9, and the capacitor C5 and the winding N s6 The connection point outputs the voltage v cs2 .

[0112] Furthermore, the winding N s6 The number of turns is N6.

[0113] In this embodiment, the resistor R9 and the capacitor C5 are connected in series to form an integration module. s6 The voltage across the two ends is the input voltage of the integration module. cs2 is the output voltage of the integration module, and the relevant formula is as follows:

[0114]

[0115] The excitation current i Lm With the transformer T r The voltage relationship is:

[0116]

[0117] From the above two formulas, it can be seen that the voltage v cs2 With the excitation current i Lm The relationship is as follows:

[0118]

[0119] Depend on Fig.11 It can be seen that the voltage v cs1 is the parasitic resistance R Lr The upper voltage can be obtained:

[0120]

[0121] When appropriate parameters are selected, We can get:

[0122]

[0123] When appropriate parameters are selected, We can get:

[0124]

[0125] Right now,

[0126] v sy7 =R Lr i o ,

[0127] It can be seen from the above formula that the voltage v sy10 With the load current i o Ratio R Lr .

[0128] Fig.13 for Fig.11 The working process simulation waveform diagram of the resonance module 1101, wherein V gs1 is the driving signal of the switch Q1, V gs2 is the driving signal of the switch Q2, i Lr is the resonant current, i Lm is the excitation current, i o is the load current, v sy10 is the output voltage of the operational amplifier A3. As can be seen from the figure, the output voltage v sy10 Can follow the load current i o Changes in the same proportion.

[0129] In summary, Fig.11 The resonant converter circuit in the embodiment only needs to add an additional winding, namely the winding N s6 The load current i can be obtained by combining simple units such as capacitors and resistors. o , will not cause additional losses, requires fewer peripheral devices, and helps to improve the efficiency and power density of the system; and is suitable for any circuit in which a resonant inductor and a transformer are connected in series, as well as a resonant circuit without an external resonant inductor and using transformer leakage inductance instead of the resonant inductor.

[0130] It should be noted that the resonant conversion circuit of the present invention is not only applicable to LLC half-bridge resonant circuits, but also to various resonant circuits, such as LCC resonant conversion circuits, series resonant conversion circuits, parallel resonant conversion circuits and other resonant conversion circuits, as well as various quasi-resonant conversion circuits.

[0131] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims

1. A resonant conversion circuit, comprising a resonant branch, a switch unit and a rectifier unit, wherein an input power source is connected to an input port of the switch unit to power the resonant conversion circuit, the switch unit, the resonant branch and the rectifier unit are connected in parallel, and an output end of the rectifier unit is connected to a load, characterized in that: The resonant conversion circuit further includes: a resonant current detection module, the input end of which is connected to the resonant branch and is used to detect the resonant current in the resonant branch, and the resonant current detection module outputs a first voltage; An excitation current detection module, the excitation current detection module is used to detect the excitation current in the resonant branch, the excitation current detection module outputs a second voltage, the output end of the excitation current detection circuit is connected in parallel with the output end of the resonant current detection circuit and outputs a third voltage; The excitation current detection module is controlled by a driving signal of the switch unit.

2. A resonant conversion circuit as claimed in claim 1, characterized in that: The resonant branch includes a resonant capacitor, a first end of the resonant capacitor is connected to a first output end of the switch unit, and an input end of the resonant current detection module is connected to two ends of the resonant capacitor. a resonant inductor, wherein a first end of the resonant inductor is connected to a second end of the resonant capacitor, A main transformer, wherein the first end of the primary side winding of the main transformer is connected to the second end of the resonant inductor, the second end of the primary side winding of the main transformer is connected to the second output end of the switch unit, the first end of the first secondary side winding of the main transformer is connected to the first input end of the rectifier unit, the second end of the first secondary side winding of the main transformer is connected to the first end of the second secondary side winding of the main transformer, and the second end of the second secondary side winding of the main transformer is connected to the second input end of the rectifier unit.

3. A resonant conversion circuit as claimed in claim 2, characterized in that: The excitation current detection module includes a third winding, a third resistor and a third capacitor, the first end of the third winding is connected to the second end of the primary side winding of the main transformer, the first end of the third resistor is connected to the second end of the third winding, the first end of the third capacitor is connected to the second end of the third resistor, the second end of the third capacitor is grounded, and the connection point between the third capacitor and the third resistor outputs the second voltage; the excitation current detection module also includes a sub-transformer, the third winding is the secondary side winding of the sub-transformer, and the driving signal of the switch unit is input at both ends of the primary side winding of the sub-transformer.

4. A resonant conversion circuit as claimed in claim 2, characterized in that: The excitation current detection module includes a third winding, a third resistor and a third capacitor, the first end of the third winding is connected to the first end of the third resistor, the second end of the third resistor is connected to the first end of the third capacitor, the second end of the third capacitor is connected to the second end of the third winding, the voltage across the third capacitor is the second voltage, and the connection point between the third capacitor and the third resistor outputs the third voltage; the excitation current detection module also includes a sub-transformer, the third winding is the secondary side winding of the sub-transformer, and the driving signal of the switch module is input at both ends of the primary side winding of the sub-transformer.

5. A resonant conversion circuit as claimed in claim 2, characterized in that: The excitation current detection module includes multiple current sources and a sixth capacitor, one end of the sixth capacitor is connected to the common end of the multiple current sources, and the sixth capacitor is connected to the output end of the resonant current detection module; the driving signal of the switch unit controls the current source and is proportional to the output current of the current source.

6. A resonant conversion circuit according to any one of claims 3 to 5, characterized in that: The resonant current detection module includes a first operational amplifier, a first capacitor, a second capacitor, a first resistor and a second resistor. The first end of the resonant capacitor is connected to the positive input end of the first operational amplifier through the second capacitor, the second end of the resonant capacitor is connected to the negative input end of the first operational amplifier through the first capacitor, the positive input end of the first operational amplifier is grounded through the second resistor, the negative input end of the first operational amplifier is connected to the output end of the first operational amplifier through the first resistor, and the output end of the first operational amplifier outputs the first voltage.

7. A resonant conversion circuit as claimed in claim 6, characterized in that: The resonant current detection module also includes a fourth resistor and a fifth resistor, and the second end of the third resistor or the sixth capacitor and a common end of the plurality of current sources are connected to the output end of the first operational amplifier via the fourth resistor and the fifth resistor.

8. A resonant conversion circuit as claimed in claim 7, characterized in that: The resonant current detection module also includes a second operational amplifier, a sixth resistor and a seventh resistor, the positive input terminal of the second operational amplifier is connected to the connection point between the fourth resistor and the fifth resistor, the negative input terminal of the second operational amplifier is grounded through the sixth resistor, and the negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through the seventh resistor.

Images