Exciting current detection circuit and driving power supply of LLC resonant converter
By directly sampling the excitation current in the transformer winding parallel current sampling module of the LLC resonant converter, the problem of inability to distinguish resonant current from excitation current in the prior art is solved, and direct detection and rapid response to the excitation current are achieved.
Patent Information
- Application Number
- CN202323396284.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-12
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2033-12-12
AI Technical Summary
The current detection method of the existing LLC resonant converter cannot directly distinguish between resonant current and excitation current, and cannot detect the transformer excitation current.
An excitation current detection circuit including an LLC control chip, a driving module, a resonance module, a transformer and a current sampling module is designed, and the excitation current is directly sampled by connecting the current sampling module in the primary or secondary windings of the transformer.
Direct detection of the transformer excitation current is realized, complex software calculations are avoided, and system response speed and reliability are improved.
Smart Images
Figure CN222439574U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of driving power supplies, and more specifically to an excitation current detection circuit and a driving power supply of an LLC resonant converter. Background Art
[0002] The LLC resonant converter is the most widely used soft switching topology and can be applied to medium and large power supplies. It is very popular for its advantages such as high efficiency, high power density and low EMI.
[0003] Among them, the most representative control chip is the LLC control chip L6599, which uses the voltage control mode and has the characteristics of the voltage control mode, but its loop response is slow. Although the currently popular LLC control chip NCP1399 uses the current control mode, its current detection method is to detect the voltage on the resonant capacitor and then indirectly use the software algorithm to obtain the voltage on the resonant capacitor. Therefore, its current loop feedforward effect is not as fast as the flyback converter or the forward converter in cycle-by-cycle response (the software algorithm needs time to judge), and it is not like the flyback converter or the forward converter that directly uses the current detection device to detect the excitation current of the transformer. Similarly, for the LLC control chip ICL5102, although it uses the current control mode, its current detection method is to detect the voltage on the resistor element connected in series in the resonant circuit and indirectly use the software algorithm to obtain the voltage. Therefore, its current loop feedforward effect is not as fast as the flyback converter or the forward converter in cycle-by-cycle response (the software algorithm needs time to judge), and it is not like the flyback converter or the forward converter that directly uses the current detection device to detect the excitation current of the transformer.
[0004] It can be seen from this that the current detection device used is connected in series in the circuit loop of the current to be detected, but the LLC resonant converter loop contains two parts of current: resonant current and excitation current. The series detection method cannot distinguish the resonant current and excitation current in the loop, and the purpose of detecting the excitation current of the transformer cannot be achieved. Utility Model Content
[0005] The technical problem to be solved by the utility model is to provide an excitation current detection circuit and a driving power supply for an LLC resonant converter.
[0006] The technical solution adopted by the utility model to solve the technical problem is: constructing an excitation current detection circuit of an LLC resonant converter, including: an LLC control chip, a drive module, a resonant module, a transformer and a current sampling module;
[0007] The input end of the driving module is connected to the LLC control chip, the output end of the driving module is connected to the input end of the resonance module, the output end of the resonance module is connected to the primary winding of the transformer, the current sampling module is connected in parallel with the primary winding or the secondary winding of the transformer, and the current sampling module is also connected to the LLC control chip;
[0008] The driving module generates a driving signal according to the control signal output by the LLC control chip;
[0009] The resonance module performs resonance based on the driving signal to obtain a resonance signal;
[0010] The transformer performs energy conversion on the resonant signal to obtain an output signal;
[0011] The current sampling module samples the excitation current of the transformer to obtain an excitation current sampling signal.
[0012] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the driving module includes: a first MOS tube and a second MOS tube;
[0013] The gate of the first MOS tube is connected to the first control terminal of the LLC control chip, the source of the first MOS tube is connected to the drain of the second MOS tube, the driving end of the LLC control chip and the input end of the resonance module, the drain of the first MOS tube is connected to the input voltage, the gate of the second MOS tube is connected to the second control terminal of the LLC control chip, and the source of the second MOS tube is grounded;
[0014] The connection end between the source of the first MOS tube and the drain of the second MOS tube is the output end of the driving module.
[0015] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the resonant module includes: a resonant inductor, a resonant capacitor and an excitation inductor;
[0016] The input end of the resonant inductor is connected to the driving end of the LLC control chip and the output end of the resonant module, the output end of the resonant inductor is connected to the input end of the resonant capacitor, the output end of the resonant capacitor is connected to the input end of the excitation inductor, the output end of the excitation inductor is grounded, and the excitation inductor is connected in parallel with the primary winding of the transformer;
[0017] The input end of the resonant inductor is the input end of the resonant module, and the connection end between the output end of the resonant capacitor and the input end of the excitation inductor is the output end of the resonant module.
[0018] The excitation current detection circuit of the LLC resonant converter described in the utility model also includes: a filtering module;
[0019] The input end of the filter module is connected to the output end of the current sampling module, and the output end of the filter module is connected to the sampling end of the LLC control chip;
[0020] The filtering module is used to filter the excitation current sampling signal and then transmit the signal to the LLC control chip.
[0021] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the current sampling module includes: a current sampling circuit and a rectifier circuit;
[0022] The input end of the current sampling circuit is connected to the output end of the resonance module, the output end of the current sampling circuit is connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is connected to the input end of the filter module;
[0023] The current sampling circuit is used to sample the excitation current of the transformer to obtain an excitation signal;
[0024] The rectifier circuit obtains the excitation current sampling signal after rectifying the excitation signal.
[0025] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the current sampling circuit includes: a sampling inductor and a sampling resistor;
[0026] The sampling inductor is connected in series with the sampling resistor to form a series circuit, and after the series circuit is formed, the sampling inductor is connected in series with the primary winding of the transformer or the secondary winding of the transformer.
[0027] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the rectifier circuit includes: a rectifier diode;
[0028] The anode of the rectifier diode is connected to the connection end of the sampling inductor and the sampling resistor, and the cathode of the rectifier diode is connected to the input end of the filter module;
[0029] The cathode of the rectifier diode is the output end of the current sampling module.
[0030] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the filtering module includes: a first resistor and a first capacitor;
[0031] The input end of the first resistor is connected to the cathode of the rectifier diode, the output end of the first resistor is connected to the input end of the first capacitor, the output end of the first capacitor is grounded, and the connection end between the input end of the first capacitor and the output end of the first resistor is also connected to the sampling end of the LLC control chip;
[0032] The input end of the first resistor is the input end of the filter module, and the connection end between the input end of the first capacitor and the output end of the first resistor is the output end of the filter module.
[0033] In the excitation current detection circuit of the LLC resonant converter described in the utility model, the LLC control chip is a current mode control chip.
[0034] The utility model also provides a driving power supply, comprising the excitation current detection circuit of the LLC resonant converter mentioned above.
[0035] The excitation current detection circuit and driving power supply of the LLC resonant converter of the utility model have the following beneficial effects: including: LLC control chip, drive module, resonant module, transformer and current sampling module; the input end of the drive module is connected to the LLC control chip, the output end of the drive module is connected to the input end of the resonant module, the output end of the resonant module is connected to the primary winding of the transformer, the current sampling module is connected in parallel with the primary winding or secondary winding of the transformer, and the current sampling module is also connected to the LLC control chip; the current sampling module samples the excitation current of the transformer to obtain the excitation current sampling signal. The utility model can directly sample the excitation current of the transformer by connecting the current sampling module in parallel with the primary winding or secondary winding of the transformer, that is, it does not require complex software calculations and can achieve the purpose of detecting the excitation current of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:
[0037] Figure 1 It is a principle block diagram of the excitation current detection circuit of the LLC resonant converter provided by the utility model;
[0038] Figure 2 The utility model provides an LLC resonant converter excitation current detection circuit of an embodiment of the circuit principle diagram. DETAILED DESCRIPTION
[0039] Figure 1 An embodiment of an excitation current detection circuit of an LLC resonant converter provided by the utility model is shown.
[0040] In order to solve the problem that the existing current detection scheme cannot directly detect the excitation current of the transformer 15 , the utility model can achieve the purpose of detecting the excitation current of the transformer 15 by connecting the current sampling module 14 in parallel with the primary winding or the secondary winding of the transformer 15 .
[0041] Specifically, Figure 1 As shown, in this embodiment, the excitation current detection circuit of the LLC resonant converter includes: an LLC control chip 11 , a driving module 12 , a resonant module 13 , a transformer 15 and a current sampling module 14 .
[0042] The input end of the driving module 12 is connected to the LLC control chip 11, the output end of the driving module 12 is connected to the input end of the resonance module 13, the output end of the resonance module 13 is connected to the primary winding of the transformer 15, the current sampling module 14 is connected in parallel with the primary winding or the secondary winding of the transformer 15, and the current sampling module 14 is also connected to the LLC control chip 11. The input end of the resonance module 13 is also connected to the driving end of the LLC control chip 11.
[0043] Furthermore, if Figure 1 As shown, the excitation current detection circuit of the LLC resonant converter further includes: a filter module 16; the input end of the filter module 16 is connected to the output end of the current sampling module 14, and the output end of the filter module 16 is connected to the sampling end of the LLC control chip 11. The filter module 16 is used to filter the excitation current sampling signal and transmit the signal to the LLC control chip 11.
[0044] Furthermore, if Figure 1 As shown, in this embodiment, the excitation current detection circuit of the LLC resonant converter further includes: an output rectifier module 17, the input end of the output rectifier module 17 is connected to the primary winding of the transformer 15, and the output end of the output rectifier module 17 outputs the output voltage.
[0045] Specifically, in this embodiment, the driving module 12 generates a driving signal according to a control signal output by the LLC control chip 11 .
[0046] The resonance module 13 performs resonance based on the driving signal to obtain a resonance signal. Specifically, in this embodiment, the resonance module 13 can eliminate the harmonics of the driving signal (the driving signal is a square wave signal) and output a sine wave of the fundamental frequency.
[0047] The transformer 15 performs energy conversion on the resonant signal to obtain an output signal. The output signal is rectified by the output rectifier module 17 to output an output voltage. Specifically, the primary winding of the transformer 15 transmits the sine wave to its secondary winding, and at the same time, the voltage is stepped up or down according to the requirements of the product, and finally the output rectifier module 17 converts the sine wave into a stable DC (i.e., output voltage) output.
[0048] The current sampling module 14 samples the excitation current of the transformer 15 to obtain an excitation current sampling signal. Specifically, in the LLC resonant converter, the excitation current of the transformer 15 is generated by the output voltage of its secondary winding reflected to the excitation inductance Lp of the primary side. Therefore, by setting the current sampling module 14, the reflected voltage of the output voltage of the secondary winding reflected to the excitation inductance Lp of the primary side will also be applied to the current sampling module 14 at the same time. Therefore, based on the current sampling module 14, the detection of the excitation current of the transformer 15 can be realized.
[0049] Optionally, the current sampling module 14 includes: a current sampling circuit 141 and a rectification circuit 142 .
[0050] The input end of the current sampling circuit 141 is connected to the output end of the resonance module 13, the output end of the current sampling circuit 141 is connected to the input end of the rectifier circuit 142, and the output end of the rectifier circuit 142 is connected to the input end of the filter module 16; the current sampling circuit 141 is used to sample the excitation current of the transformer 15 to obtain an excitation signal; the rectifier circuit 142 obtains an excitation current sampling signal after rectifying the excitation signal.
[0051] The following is a specific example for explanation. Figure 2 A preferred embodiment provided by the utility model is shown. In this embodiment, the current sampling module 14 is connected in parallel with the primary winding of the transformer 15 .
[0052] Specifically, Figure 2 As shown, in this embodiment, the driving module 12 includes: a first MOS transistor Q1 and a second MOS transistor Q2; the gate of the first MOS transistor Q1 is connected to the first control end of the LLC control chip 11, the source of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2, the driving end of the LLC control chip 11 and the input end of the resonance module 13, the drain of the first MOS transistor Q1 is connected to the input voltage, the gate of the second MOS transistor Q2 is connected to the second control end of the LLC control chip 11, and the source of the second MOS transistor Q2 is grounded. Among them, the connection end between the source of the first MOS transistor Q1 and the drain of the second MOS transistor Q2 is the output end of the driving module 12.
[0053] In this embodiment, the resonance module 13 includes: a resonance inductor Lr, a resonance capacitor Cr and an excitation inductor Lp.
[0054] The input end of the resonant inductor Lr is connected to the driving end of the LLC control chip 11 and the output end of the resonant module 13, the output end of the resonant inductor Lr is connected to the input end of the resonant capacitor Cr, the output end of the resonant capacitor Cr is connected to the input end of the excitation inductor Lp, the output end of the excitation inductor Lp is grounded, and the excitation inductor Lp is connected in parallel with the primary winding of the transformer 15. Among them, the input end of the resonant inductor Lr is the input end of the resonant module 13, and the connection end between the output end of the resonant capacitor Cr and the input end of the excitation inductor Lp is the output end of the resonant module 13. Figure 2 As shown, the input end of the resonant inductor Lr is respectively connected to the source of the first MOS transistor Q1, the drain of the second MOS transistor Q2 and the driving end of the LLC control chip 11.
[0055] like Figure 2 As shown, in this embodiment, the current sampling circuit 141 includes: a sampling inductor L and a sampling resistor RS. The sampling inductor L and the sampling resistor RS are connected in series to form a series circuit, and after forming the series circuit, they are connected to the primary winding of the transformer 15. Alternatively, in some other embodiments, after the sampling inductor L and the sampling resistor RS are connected in series to form a series circuit, the series circuit is connected in series with the secondary winding of the transformer 15. Since the current sampling module 14 is connected in parallel with the primary winding or the secondary winding of the transformer 15, when the transformer 15, the expression is: Ip=N*Vout / L p (where: Ip is the excitation current, N is the turns ratio between the primary winding and the secondary winding of the transformer 15, Vout is the output voltage, L p is the inductance of the excitation inductance Lp). Therefore, by connecting the sampling inductance L in parallel with the primary winding of the transformer 15, the voltage equivalent to the output voltage of the secondary in the LLC resonant converter reflected to the excitation inductance Lp of the primary side of the transformer 15 is also applied to the sampling inductance LL. Similarly, the formula Ip1=N*Vout / L p1 (where: Ip1 is the excitation current of the sampling inductor L, N is the turns ratio between the primary and secondary of the transformer 15, Vout is the output voltage, L p1 is the inductance of the sampling inductor L), and this reflected voltage also generates an excitation current in the sampling inductor L. In addition, since the excitation current on the sampling inductor L is much smaller than the excitation current of the transformer 15, it does not affect the operation of the LLC resonant converter. Among them, the principle of connecting the sampling inductor L in parallel with the secondary winding of the transformer 15 is the same, which will not be repeated here.
[0056] like Figure 2As shown, in this embodiment, the rectifier circuit 142 includes: a rectifier diode D3; the anode of the rectifier diode D3 is connected to the connection end of the sampling inductor L and the sampling resistor RS, and the cathode of the rectifier diode D3 is connected to the input end of the filter module 16; the cathode of the rectifier diode D3 is the output end of the current sampling module 14.
[0057] like Figure 2 As shown, in this embodiment, the filter module 16 includes: a first resistor R1 and a first capacitor C1. The input end of the first resistor R1 is connected to the cathode of the rectifier diode D3, the output end of the first resistor R1 is connected to the input end of the first capacitor C1, the output end of the first capacitor C1 is grounded, and the connection end between the input end of the first capacitor C1 and the output end of the first resistor R1 is also connected to the sampling end of the LLC control chip 11. Among them, the input end of the first resistor R1 is the input end of the filter module 16, and the connection end between the input end of the first capacitor C1 and the output end of the first resistor R1 is the output end of the filter module 16.
[0058] like Figure 2 As shown, in this embodiment, the output rectifier module 17 includes: a first diode D1, a second diode D2 and an output capacitor CE1. The anode of the first diode D1 is connected to the first end of the secondary winding of the transformer 15, the cathode of the first diode D1 is connected to the first end of the output capacitor CE1 and the cathode of the second diode D2, and the connection end of the first diode D1, the second diode D2 and the output capacitor CE1 outputs the output voltage, the second end of the output capacitor CE1 is connected to the second end of the secondary winding of the transformer 15, and the anode of the second diode D2 is connected to the second end of the secondary winding of the transformer 15.
[0059] Specifically, Figure 2 As shown, when the output voltage of the secondary winding of the transformer 15 generates a reflected voltage (set as: V 反 , V 反 =N*Vout) is applied to the excitation inductor Lp on the primary side of the transformer 15, since the sampling inductor L is connected in parallel with the transformer 15, the reflected voltage is simultaneously applied to the sampling inductor L, thereby generating a sampled excitation current, and the sampled excitation current generates a sawtooth voltage signal (i.e., the aforementioned excitation signal) through the sampling resistor RS, and the sawtooth voltage signal is first forward rectified by the rectifier diode D3 (negative voltage is generated by the sampling resistor RS, and the rectifier diode D3 can eliminate the negative voltage on the sampling resistor RS), and then filtered by the first resistor R1 and the first capacitor C1 through leading edge blanking, and the filtered voltage signal (i.e., the aforementioned excitation current sampling signal) is transmitted to the LLC control chip 11. Among them, the sawtooth voltage signal generated by the sampling resistor RS is obtained by corresponding conversion of the excitation current generated on the sampling inductor L.
[0060] Furthermore, in this embodiment, the LLC control chip 11 is a current mode control chip, wherein the current mode control chip used can be a general current mode control chip, such as UC3846 series.
[0061] The utility model can directly detect the excitation current of the transformer 15 of the LLC resonant converter by using a parallel sampling inductor L, without the need for complex software calculations and complex hardware structures, and can meet product needs by using a general current mode control chip, thereby reducing the system design difficulty of the LLC resonant converter. At the same time, since there is no need for complex software calculations, the response speed and reliability of the LLC resonant converter system can also be improved.
[0062] The utility model also provides a driving power supply, wherein the driving power supply comprises the excitation current detection circuit of the LLC resonant converter disclosed in the utility model.
[0063] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot limit the protection scope of the utility model. All equivalent changes and modifications made to the scope of the claims of the utility model should fall within the scope of the claims of the utility model.
Claims
1. An excitation current detection circuit for an LLC resonant converter, characterized in that: include: LLC control chip, drive module, resonance module, transformer and current sampling module; The input end of the driving module is connected to the LLC control chip, the output end of the driving module is connected to the input end of the resonance module, the output end of the resonance module is connected to the primary winding of the transformer, the current sampling module is connected in parallel with the primary winding or the secondary winding of the transformer, and the current sampling module is also connected to the LLC control chip; The driving module generates a driving signal according to the control signal output by the LLC control chip; The resonance module performs resonance based on the driving signal to obtain a resonance signal; The transformer performs energy conversion on the resonant signal to obtain an output signal; The current sampling module samples the excitation current of the transformer to obtain an excitation current sampling signal.
2. The excitation current detection circuit of the LLC resonant converter according to claim 1, characterized in that: The driving module includes: a first MOS tube and a second MOS tube; The gate of the first MOS tube is connected to the first control terminal of the LLC control chip, the source of the first MOS tube is connected to the drain of the second MOS tube, the driving end of the LLC control chip and the input end of the resonance module, the drain of the first MOS tube is connected to the input voltage, the gate of the second MOS tube is connected to the second control terminal of the LLC control chip, and the source of the second MOS tube is grounded; The connection end between the source of the first MOS tube and the drain of the second MOS tube is the output end of the driving module.
3. The excitation current detection circuit of the LLC resonant converter according to claim 2, characterized in that: The resonance module includes: a resonance inductor, a resonance capacitor and an excitation inductor; The input end of the resonant inductor is connected to the driving end of the LLC control chip and the output end of the resonant module, the output end of the resonant inductor is connected to the input end of the resonant capacitor, the output end of the resonant capacitor is connected to the input end of the excitation inductor, the output end of the excitation inductor is grounded, and the excitation inductor is connected in parallel with the primary winding of the transformer; The input end of the resonant inductor is the input end of the resonant module, and the connection end between the output end of the resonant capacitor and the input end of the excitation inductor is the output end of the resonant module.
4. The excitation current detection circuit of the LLC resonant converter according to claim 1, characterized in that: Also includes: Filter module; The input end of the filter module is connected to the output end of the current sampling module, and the output end of the filter module is connected to the sampling end of the LLC control chip; The filtering module is used to filter the excitation current sampling signal and then transmit the signal to the LLC control chip.
5. The excitation current detection circuit of the LLC resonant converter according to claim 4, characterized in that: The current sampling module includes: a current sampling circuit and a rectification circuit; The input end of the current sampling circuit is connected to the output end of the resonance module, the output end of the current sampling circuit is connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is connected to the input end of the filter module; The current sampling circuit is used to sample the excitation current of the transformer to obtain an excitation signal; The rectifier circuit obtains the excitation current sampling signal after rectifying the excitation signal.
6. The excitation current detection circuit of the LLC resonant converter according to claim 5, characterized in that: The current sampling circuit comprises: a sampling inductor and a sampling resistor; The sampling inductor is connected in series with the sampling resistor to form a series circuit, and after the series circuit is formed, the sampling inductor is connected in series with the primary winding of the transformer or the secondary winding of the transformer.
7. The excitation current detection circuit of the LLC resonant converter according to claim 6, characterized in that: The rectifier circuit comprises: a rectifier diode; The anode of the rectifier diode is connected to the connection end of the sampling inductor and the sampling resistor, and the cathode of the rectifier diode is connected to the input end of the filter module; The cathode of the rectifier diode is the output end of the current sampling module.
8. The excitation current detection circuit of the LLC resonant converter according to claim 7, characterized in that: The filtering module includes: a first resistor and a first capacitor; The input end of the first resistor is connected to the cathode of the rectifier diode, the output end of the first resistor is connected to the input end of the first capacitor, the output end of the first capacitor is grounded, and the connection end between the input end of the first capacitor and the output end of the first resistor is also connected to the sampling end of the LLC control chip; The input end of the first resistor is the input end of the filter module, and the connection end between the input end of the first capacitor and the output end of the first resistor is the output end of the filter module.
9. The excitation current detection circuit of the LLC resonant converter according to any one of claims 1 to 8, characterized in that: The LLC control chip is a current mode control chip.
10. A driving power supply, characterized in that: An excitation current detection circuit for an LLC resonant converter comprising any one of claims 1 to 9.