Voltage type LLC control protection circuit and power supply

Abstract

The invention discloses a voltage-type control LLC protection circuit and a power supply, which are applied to the field of LLC circuits, a sampling circuit is used for acquiring a resonant cavity current signal in a voltage-type control LLC circuit to obtain a first electric signal, and a signal processing circuit is used for converting the first electric signal into a required second electric signal and transmitting the second electric signal to a master control IC chip. The output end of the master control IC chip is connected with the control end of a switch tube in a secondary circuit in the voltage type control LLC circuit, and when the master control IC chip judges that abnormal current occurs in a resonant cavity of the voltage type control LLC circuit, the switch tube in the secondary circuit for controlling the voltage type control LLC circuit is switched off, so that the current in the resonant cavity is prevented from losing restraint, and the service life of the resonant cavity is prolonged. The problems that the resonant cavity current is too large and the current regulation and control time is uncontrollable when the voltage type control LLC is in an abnormal state are solved, and accurate sampling, processing and control of the resonant cavity current of the voltage type control LLC circuit are effectively achieved.

Description

Technical Field

[0001] The present invention relates to the field of LLC circuits, and in particular to a voltage-type LLC protection circuit and power supply. Background Art

[0002] In the field of modern power electronics technology, LLC resonant converters are widely used in many occasions due to their excellent performance characteristics, such as power adapters, LED lighting drivers, industrial power supplies, etc.

[0003] Voltage-type control is one of the commonly used control strategies for LLC converters. It adjusts the switching frequency or duty cycle of the converter by sampling and feedback of the output voltage to maintain a stable output voltage. However, in actual operation, the voltage-type control scheme adopted by the secondary cannot add current control in the logic, which will cause the current of the resonant cavity to lose control and thus damage the device.

[0004] The common solutions at present are: connecting a diode in parallel with a resonant capacitor. The specific control circuit diagram is as follows Figure 1 As shown, this places high demands on the diode, requiring the diode to have a high withstand value, ultra-fast reverse recovery, and a certain power tolerance. However, this method cannot adjust the maximum current and duration, and only relies on the diode to passively absorb energy until the startup fails to protect the voltage-type control LLC circuit.

[0005] It can be seen that how to accurately limit the maximum value of the resonant cavity current and the current control time of the voltage-type controlled LLC under abnormal conditions is a technical problem that needs to be urgently solved by people in this field. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a protection circuit and power supply for a voltage-type controlled LLC, which solves the problem of excessive resonant cavity current in the voltage-type controlled LLC under abnormal conditions. The specific scheme is as follows:

[0007] In a first aspect, the present application provides a voltage-type control LLC protection circuit, including: a sampling circuit, a signal processing circuit and a main control IC chip;

[0008] The sampling circuit is connected to the resonant inductor in the resonant cavity of the voltage-type control LLC circuit, and is used to collect a first electrical signal representing the current flowing through the resonant cavity;

[0009] The signal processing circuit is connected to the sampling circuit and is used to process the first electrical signal to obtain a second electrical signal;

[0010] The main control IC chip is connected to the voltage output end of the signal processing circuit, and is used to obtain the second electrical signal, and determine the current value of the resonant cavity of the voltage-type controlled LLC circuit according to the second electrical signal, and then control the switching of the switch tube in the secondary circuit of the voltage-type controlled LLC circuit.

[0011] Optionally, the sampling circuit is a first secondary winding of the resonant inductor, wherein an iron core is arranged between the first secondary winding and the resonant inductor.

[0012] Optionally, the sampling circuit includes a first primary winding, a second secondary winding, and an iron core arranged between the first primary winding and the second secondary winding, and the first primary winding is connected in series with the resonant inductor.

[0013] Optionally, the signal processing circuit includes: a rectifier module, a first filter circuit, a second filter circuit and a voltage divider circuit;

[0014] The rectifier module is connected to the sampling circuit and is used to rectify the AC signal sampled by the sampling circuit;

[0015] The first filtering circuit is connected to the rectifier module and is used to filter the rectified signal;

[0016] The voltage divider circuit is connected to the first filter circuit and is used to divide the filtered electrical signal to obtain a sampling signal;

[0017] The second filtering circuit is connected to the voltage divider circuit and is used for filtering the sampling signal to obtain the second signal.

[0018] Optionally, the rectifier module includes: a full-bridge rectifier circuit or a half-wave rectifier circuit or a full-wave rectifier circuit;

[0019] The input end of the rectifier module is connected to the sampling circuit, and the output end of the rectifier module is connected to the voltage divider circuit.

[0020] Optionally, the first filtering circuit includes: a first capacitor and a first resistor;

[0021] The first end of the first capacitor and the first end of the first resistor are connected to the first output end of the rectifier module;

[0022] The second end of the first capacitor and the second end of the first resistor are connected to the second output end of the rectifier module.

[0023] Optionally, the voltage divider circuit includes: a second resistor, a third resistor and a fourth resistor;

[0024] The first output end of the rectifier module is connected to the first end of the second resistor;

[0025] The second output end of the rectifier module is connected to the second end of the fourth resistor;

[0026] The second end of the second resistor is connected to the first end of the third resistor, and a common end of the two serves as a first sampling end;

[0027] The second end of the third resistor is connected to the first end of the fourth resistor, and a common end of the two serves as a second sampling end;

[0028] The first sampling terminal is connected to the second sampling terminal, and a common terminal of the two is connected to the input terminal of the main control IC chip as a voltage output terminal.

[0029] Optionally, the second filtering circuit includes: a second capacitor and a third capacitor;

[0030] The first end of the second capacitor is connected to the first sampling end;

[0031] The first end of the third capacitor is connected to the second sampling end, and the second end of the third capacitor is connected to the second end of the fourth resistor.

[0032] Optionally, it further includes: a first diode and a second diode;

[0033] The anode of the first diode is connected to the first output terminal of the signal processing circuit, and the cathode of the first diode is connected to the voltage output terminal;

[0034] An anode of the second diode is connected to the second output terminal of the signal processing circuit, and a cathode of the first diode is connected to the voltage output terminal.

[0035] In a second aspect, the present application provides a power supply, characterized in that it includes the voltage-type control LLC protection circuit.

[0036] It can be seen that in this application, the sampling circuit collects the resonant cavity current signal in the voltage-type controlled LLC circuit to obtain the first electrical signal, and the signal processing circuit converts the first electrical signal into the required second electrical signal and transmits it to the main control IC chip. The output end of the main control IC chip is connected to the control end of the switch tube in the secondary circuit of the voltage-type controlled LLC circuit. When the main control IC chip determines that an abnormal current appears in the resonant cavity of the voltage-type controlled LLC circuit, the switch tube in the secondary circuit of the voltage-type controlled LLC circuit is turned off, thereby preventing the current in the resonant cavity from being uncontrolled and damaging the device, solving the problem of excessive resonant cavity current in the voltage-type controlled LLC under abnormal conditions, and accurately limiting the maximum value of the resonant cavity current and current control time of the voltage-type controlled LLC under abnormal conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0038] Figure 1 A voltage-type control LLC protection circuit provided in the related art;

[0039] Figure 2 A voltage-type LLC protection circuit provided in an embodiment of the present application;

[0040] Figure 3 A voltage-type LLC protection circuit provided in an embodiment of the present application;

[0041] Figure 4 A test waveform diagram of a resonant cavity current provided in an embodiment of the present application;

[0042] Figure 5 A test waveform diagram of a resonant cavity current provided in an embodiment of the present application;

[0043] The reference numerals are as follows: 10 is a signal processing circuit, 11 is a sampling circuit, 101 is a rectifier module, 102 is a first filter circuit, 103 is a voltage divider circuit, and 104 is a second filter circuit. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments 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.

[0045] The core of this application is to provide a voltage-type LLC protection circuit.

[0046] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0047] In the field of modern power electronics technology, LLC resonant converters are widely used in many occasions due to their excellent performance characteristics, such as power adapters, LED lighting drivers, industrial power supplies, etc.

[0048] Voltage-type control is one of the commonly used control strategies for LLC converters. It adjusts the switching frequency or duty cycle of the converter by sampling and feedback of the output voltage to maintain a stable output voltage. However, in actual operation, the voltage-type control scheme adopted by the secondary cannot add current control in the logic, which will cause the current of the resonant cavity to lose control and thus damage the device.

[0049] The common solutions at present are: connecting a diode in parallel with a resonant capacitor. The specific control circuit diagram is as follows Figure 1 As shown, this places high demands on the diode, requiring the diode to have a high withstand value, ultra-fast reverse recovery, and a certain power tolerance. However, this method cannot adjust the maximum current and duration, and only relies on the diode to passively absorb energy until the startup fails to protect the voltage-type control LLC circuit.

[0050] It can be seen that how to limit the resonant cavity current of the voltage-controlled LLC under abnormal conditions is a technical problem that needs to be solved urgently by people in this field.

[0051] See also Figure 2 As shown, in order to solve the above problems, this embodiment discloses a voltage-type control LLC protection circuit, including: a sampling circuit, a signal processing circuit 10 and a main control IC chip;

[0052] The sampling circuit is connected to the resonant inductor in the resonant cavity of the voltage-type control LLC circuit, and is used to collect a first electrical signal representing the current flowing through the resonant cavity;

[0053] The signal processing circuit 10 is connected to the sampling circuit and is used to process the first electrical signal to obtain a second electrical signal;

[0054] The main control IC chip is connected to the voltage output terminal Vout of the signal processing circuit 10, and is used to obtain the second electrical signal, and determine the current value of the resonant cavity of the voltage-type controlled LLC circuit according to the second electrical signal, and then control the switch of the switch tube in the secondary circuit of the voltage-type controlled LLC circuit.

[0055] As shown in the figure, when the voltage-controlled LLC circuit is working, current flows through the resonant inductor in the resonant cavity, and the sampling circuit converts the current flowing through the resonant inductor into a first electrical signal that can characterize the current flowing through the resonant cavity. According to the selection of the sampling circuit, the first electrical signal can be a current signal or a voltage signal. The ultimate goal of different sampling methods is to output a secondary voltage signal that increases proportionally with the increase of the resonant cavity current in the voltage-controlled LLC circuit. It can be understood that the magnitude of the current also indirectly reflects the magnitude of the power.

[0056] The signal processing circuit 10 is connected to the sampling circuit. The different processing of the first electrical signal by the signal processing circuit 10 can realize the circuit protection of different abnormal conditions of the voltage-type control LLC circuit, such as power protection circuit or short circuit abnormal protection circuit. At the same time, the signal processing circuit 10 has the function of filtering out high-frequency noise interference to obtain a second electrical signal that stably and accurately reflects the characteristics of the resonant cavity current and transmits it to the main control IC chip. The main control IC chip has a specific pin connected to the voltage output terminal Vout of the signal processing circuit 10 to obtain the processed second electrical signal.

[0057] The ADC inside the main control IC chip samples the second electrical signal at a preset sampling frequency, and converts the sampled voltage value into a corresponding current value according to a preset conversion formula. Based on this current value, the main control IC chip controls the switch of the switch tube in the secondary circuit of the voltage-type control LLC circuit according to the established control strategy. For example, when the current value exceeds the preset 6A overload threshold, the main control IC chip will adjust the drive pulse width of the switch tube and reduce the conduction time of the switch tube, thereby limiting the further increase of the resonant cavity current and protecting the components in the circuit from damage by excessive current; and when the current value is within the normal working range, the normal switching frequency and duty cycle of the switch tube are maintained to ensure stable and efficient operation of the LLC circuit. At the same time, the main control IC chip can also display the obtained current value or power through a screen display device to achieve the additional function of real-time monitoring.

[0058] Figure 3 and Figure 4 The test waveform diagram of the resonant cavity current in the voltage-type control LLC circuit without adding a protection circuit and after adding a protection circuit is shown. It can be clearly seen that after adding the protection circuit, the current amplitude is reduced and the protection time is shortened, making the device more reliable. It can be seen that in the embodiment of the present application, the resonant cavity current signal in the voltage-type control LLC circuit is collected by the sampling circuit to obtain the first electrical signal, and the first electrical signal is converted into the required second electrical signal through the signal processing circuit 10 and transmitted to the main control IC chip. The output end of the main control IC chip is connected to the control end of the switch tube in the secondary circuit of the voltage-type control LLC circuit. When the main control IC chip determines that the resonant cavity of the voltage-type control LLC circuit has an abnormal current, the switch tube in the secondary circuit of the control voltage-type control LLC circuit is turned off, thereby avoiding the current in the resonant cavity from being restrained and damaging the device, solving the problem of excessive resonant cavity current in the voltage-type control LLC in an abnormal state. Effectively realize the accurate sampling, processing and control of the resonant cavity current of the voltage-type control LLC circuit, and improve the reliability and stability of the entire circuit system.

[0059] The sampling method of the sampling circuit has different solutions based on the selection of different signals. According to the above embodiment, this embodiment provides a specific solution, where the sampling circuit is the first secondary winding of the resonant inductor, wherein an iron core is arranged between the first secondary winding and the resonant inductor.

[0060] In this embodiment, the sampling circuit uses the first secondary winding of the resonant inductor to implement the current sampling function. The resonant inductor is a key component in the voltage-controlled LLC circuit. The first secondary winding of the resonant inductor has a specific turns ratio relationship with the main winding. The effective value of the resonant inductor voltage , where a is the coefficient, b is the constant, V1 is the resonant inductor voltage, I LLC It is the current flowing through the voltage-controlled LLC circuit. When the voltage-controlled LLC circuit operates normally, current flows through the main winding. According to the principle of electromagnetic induction, a first electrical signal proportional to the main winding current will be induced in the first secondary winding. According to the inductor primary-to-secondary voltage is proportional to the turns ratio: , V1 is the resonant inductor voltage, V2 is the first secondary winding voltage, is the turns ratio of the resonant inductor to the first secondary winding. Then the effective voltage value of V2 of the secondary winding can be obtained: .

[0061] According to the above embodiment, this embodiment provides a specific solution, the sampling circuit includes a first primary winding, a second secondary winding and an iron core arranged between the first primary winding and the second secondary winding, and the first primary winding is connected in series with the resonant inductor.

[0062] The sampling circuit adopts a structure based on the transformer principle, in which the first primary winding and the resonant inductor are connected in series to the resonant cavity loop of the voltage-type control LLC circuit. When the LLC circuit is working, the resonant cavity current will flow through the first primary winding. An iron core is set between the first primary winding and the second secondary winding. The iron core is made of high magnetic permeability materials, such as ferrite, to ensure good magnetic coupling effect. Since the first primary winding is connected in series with the resonant inductor, the residual current is equal. According to the inductor primary and secondary currents are inversely proportional to the turns ratio: , the effective value of the current in the second secondary winding can be obtained: , where I1 is the current flowing through the first primary winding, that is, the current flowing through the resonant cavity in the voltage-type controlled LLC circuit, and I2 is the current flowing through the second secondary winding. is the turns ratio of the first primary winding to the second secondary winding.

[0063] According to the above embodiment, this embodiment provides a specific solution, the signal processing circuit 10 includes: a rectifier module 101, a first filter circuit 102, a second filter circuit 104 and a voltage divider circuit 103;

[0064] The rectifier module 101 is connected to the sampling circuit and is used to rectify the AC signal sampled by the sampling circuit;

[0065] The first filter circuit 102 is connected to the rectifier module 101 and is used to filter the rectified signal;

[0066] The voltage divider circuit 103 is connected to the first filter circuit 102 and is used to divide the filtered electrical signal to obtain a sampling signal;

[0067] The second filter circuit 104 is connected to the voltage divider circuit 103 and is used for filtering the sampled signal to obtain a second electrical signal.

[0068] like Figure 2 As shown, the first filter circuit 102 rectifies the AC signal sampled by the sampling circuit after the rectifier module 101. Since the rectified DC voltage is not a stable linear voltage, but contains a large amount of AC components, i.e., ripple voltage. The filter module suppresses and filters these AC ripples to make the output voltage smoother, more stable, and close to the ideal DC voltage. At the same time, the rectified voltage ripple contains AC components of various frequencies. These high-frequency components will radiate outward in the form of electromagnetic waves, generate electromagnetic interference to surrounding electronic equipment, and affect their normal operation. The filter module can effectively attenuate these high-frequency interference signals and reduce the intensity of electromagnetic radiation.

[0069] The voltage divider circuit 103 processes the first electrical signal based on different protection functions to meet the protection circuit requirements of different measurement standards. For example, in the power and short circuit protection circuit for the voltage-type control LLC circuit, the protection value of the abnormal short circuit is higher than the protection value of the overpower. In most circuits, the abnormal short circuit protection value is high and the protection response time is short; in order to prevent false triggering, the overpower protection requires a certain delay time, and the protection value is lower than the abnormal protection point. Therefore, the voltage divider circuit 103 is used to process the first electrical signal to meet the needs of obtaining different measurement data under different protection requirements.

[0070] The second filter circuit 104 is connected to the voltage divider circuit 103, and transmits the divided sampling signal to the main control IC chip. After passing through the rectifier module 101 and the first filter circuit 102, although most of the AC ripple components have been filtered out, there may still be some residual ripples. At the same time, the central control IC chip usually has high requirements for the quality of the input signal, such as signal stability and purity. The second filter circuit 104 further adjusts the sampling signal according to the specific input characteristics of the central control IC chip.

[0071] According to the above embodiment, this embodiment provides a specific solution, the rectifier module 101 includes: a full-bridge rectifier circuit or a half-wave rectifier circuit or a full-wave rectifier circuit;

[0072] The input end of the rectifier module 101 is connected to the sampling circuit, and the output end of the rectifier module 101 is connected to the voltage divider circuit 103 .

[0073] like Figure 2 As shown, when the rectifier module 101 is a full-bridge rectifier circuit and the sampling circuit is the first secondary winding of the resonant inductor, the voltage V at point A is A is the output voltage after full-wave rectification of the V2 waveform, and V2 is the first electrical signal. Since the first electrical signal is a voltage signal and the voltage waveform is close to a sine wave, according to the relationship between the average value and the effective value of the sine wave, it can be obtained that V A The average value of voltage: ;like Figure 3 As shown, when the sampling circuit is a first primary winding, a second secondary winding, and an iron core arranged between the first primary winding and the second secondary winding, the current I at A A is the output current after full-wave rectification of the I1 waveform. The current waveform is close to a sine wave. According to the relationship between the average value and the effective value of the sine wave, it can be concluded that I A Average value of current: When the rectifier module 101 is a half-wave rectifier circuit, the average value of the output DC voltage V A The relationship with the effective value V2 of the input AC voltage is: , when the rectifier module 101 is a full-wave rectifier circuit, .

[0074] According to the above embodiment, this embodiment provides a specific solution, the first filter circuit 102 includes: a first capacitor C1 and a first resistor R1;

[0075] The first end of the first capacitor C1 and the first end of the first resistor R1 are connected to the first output end of the rectifier module 101;

[0076] The second end of the first capacitor C1 and the second end of the first resistor R1 are connected to the second output end of the rectifier module 101 .

[0077] Depend on Figure 2 It can be seen that the first filter circuit 102 is an RC filter circuit. When the rectified DC voltage is input, the capacitor has the characteristic of "isolating DC and passing AC", and it will shunt the AC component. For high-frequency ripples, the capacitive reactance of the capacitor is very small, and the high-frequency ripples can be easily released through the capacitor. The resistor mainly plays the role of limiting current and dividing voltage. It cooperates with the capacitor to reduce the ripple component in the output voltage. The first filter circuit 102 serves as a preliminary filtering link to reduce the ripple in the rectified sampling signal and provide a relatively smooth DC voltage for the subsequent circuit. At the same time, due to its simple circuit and low cost, it has certain advantages in circuit design cost.

[0078] According to the above embodiment, this embodiment provides a specific solution, the voltage divider circuit 103 includes: a second resistor R2, a third resistor R3 and a fourth resistor R4;

[0079] The first output terminal of the rectifier module 101 is connected to the first end of the second resistor R2;

[0080] The second output terminal of the rectifier module 101 is connected to the second end of the fourth resistor R4;

[0081] The second end of the second resistor R2 is connected to the first end of the third resistor R3, and a common end of the two serves as a first sampling end;

[0082] The second end of the third resistor R3 is connected to the first end of the fourth resistor R4, and a common end of the two serves as a second sampling end;

[0083] The first sampling terminal is connected to the second sampling terminal, and a common terminal of the two is used as a voltage output terminal Vout and connected to an input terminal of a main control IC chip.

[0084] Since detecting the resonant cavity current is equivalent to detecting the resonant cavity power, the protection circuit of the voltage-controlled LLC in this example can be used as both an overpower protection circuit and a short-circuit abnormality protection circuit. In the protection mechanism, the protection value of the short-circuit abnormality is higher than the protection value of the overpower

[0085] In a specific embodiment, the current value corresponding to the over-power protection of most circuits is lower than the current value corresponding to the abnormal short-circuit protection. According to the formula, the voltage at the first sampling terminal B is higher than the voltage at the second sampling terminal C, which is equivalent to requiring a lower resonant cavity current to make the voltage at the first sampling terminal B reach a preset value. Therefore, the voltage at the first sampling terminal B is selected as the over-power protection point in this embodiment.

[0086] In a specific embodiment, the current value corresponding to the abnormal short circuit protection of most circuits is high. According to the formula, it can be obtained that the voltage at the second sampling terminal point C is lower than that at the first sampling terminal point B, which is equivalent to requiring a higher resonant cavity current to make the voltage at the second sampling terminal point C reach a preset value. At the same time, the abnormal protection requires a fast response, so the voltage at the second sampling terminal point C is selected as the short circuit abnormal protection point in this embodiment.

[0087] When the voltage at point A is known, the voltage at point B can be obtained according to the voltage division of the second resistor R2, the third resistor R3, and the fourth resistor R4. , voltage at point C By dividing the voltage and bringing in the resistance values ​​respectively, the voltage of the first sampling terminal and the second sampling terminal can be obtained. Then, by adjusting the resistance values ​​of the second resistor R2, the third resistor R3, and the fourth resistor R4, the numerical input of the short circuit abnormal point C and the overpower protection point B can be flexibly adjusted to achieve the regulation of the voltage output terminal Vout value.

[0088] According to the above embodiment, this embodiment provides a specific solution, the second filtering circuit 104 includes: a second capacitor C2 and a third capacitor C3;

[0089] A first terminal of the second capacitor C2 is connected to the first sampling terminal;

[0090] A first end of the third capacitor C3 is connected to the second sampling end, and a second end of the third capacitor C3 is connected to the second end of the fourth resistor R4.

[0091] It can be seen from the above embodiments that the voltage at point B of the first sampling terminal is an over-power protection point. In order to prevent abnormal triggering, the over-power protection needs to delay the response. Therefore, the second capacitor C2 selects a capacitor with a larger capacitance for delay and filtering. The voltage at point C of the second sampling terminal is an abnormal circuit protection point. The response time required for short-circuit abnormal protection is short. The first capacitor C1 selects a capacitor with a smaller capacitance than the second capacitor C2, which mainly plays a filtering role on the signal.

[0092] According to the above embodiment, this embodiment provides a specific solution, further comprising: a first diode D1 and a second diode D2;

[0093] An anode of the first diode D1 is connected to the first output terminal of the signal processing circuit 10, and a cathode of the first diode D1 is connected to the voltage output terminal Vout;

[0094] An anode of the second diode D2 is connected to the second output terminal of the signal processing circuit 10 , and a cathode of the first diode D1 is connected to the voltage output terminal Vout.

[0095] like Figure 2 As shown, the first diode D1 and the second diode D2 are connected to the voltage output terminal Vout, and the voltage output terminal Vout is connected to the central control IC chip. The central control IC chip is usually made based on semiconductor technology, and contains many voltage-sensitive electronic components such as transistors. These components generally have a specific operating voltage range and are designed to work in the forward direction. If a reverse voltage is applied to the input terminal of the chip, the components inside the chip may be damaged. The diode has unidirectional conductivity. When the first diode D1 and the second diode D2 are set between the central control IC chip and the voltage output terminal Vout, the first diode D1 and the second diode D2 can prevent the reverse voltage from entering the chip. When the second electrical signal fluctuates or other components in the circuit fail and cause a reverse voltage pulse, the first diode D1 and / or the second diode D2 will be cut off, so that the reverse voltage cannot pass, thereby protecting the chip.

[0096] At the same time, the forward conduction voltage of the diode is relatively fixed. When the voltage at the voltage output terminal Vout exceeds a certain amplitude, the diode will conduct, limiting the amplitude of the input signal to the forward conduction voltage of the diode plus a smaller range. This can prevent excessive input voltage spikes from damaging the central control IC chip, so that the voltage input to the chip will not exceed the safe range that the central control IC chip can withstand.

[0097] Finally, this embodiment provides a power supply, including the above-mentioned voltage-type controlled LLC protection circuit.

[0098] The above is a detailed introduction to the protection circuit and power supply of the voltage-type controlled LLC provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0099] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A voltage-type controlled LLC protection circuit, characterized in that: include: Sampling circuit, signal processing circuit and main control IC chip; The sampling circuit is connected to the resonant inductor in the resonant cavity of the voltage-type control LLC circuit, and is used to collect a first electrical signal representing the current flowing through the resonant cavity; The signal processing circuit is connected to the sampling circuit and is used to process the first electrical signal to obtain a second electrical signal; The main control IC chip is connected to the voltage output end of the signal processing circuit, and is used to obtain the second electrical signal, and determine the current value of the resonant cavity of the voltage-type controlled LLC circuit according to the second electrical signal, and then control the switching of the switch tube in the secondary circuit of the voltage-type controlled LLC circuit.

2. The voltage-type controlled LLC protection circuit according to claim 1, characterized in that: The sampling circuit is a first secondary winding of the resonant inductor, wherein an iron core is provided between the first secondary winding and the resonant inductor.

3. The voltage-type controlled LLC protection circuit according to claim 1, characterized in that: The sampling circuit includes a first primary winding, a second secondary winding, and an iron core arranged between the first primary winding and the second secondary winding, and the first primary winding is connected in series with the resonant inductor.

4. The voltage-type controlled LLC protection circuit according to claim 1, characterized in that: The signal processing circuit comprises: a rectifier module, a first filter circuit, a second filter circuit and a voltage divider circuit; The rectifier module is connected to the sampling circuit and is used to rectify the AC signal sampled by the sampling circuit; The first filtering circuit is connected to the rectifier module and is used to filter the rectified signal; The voltage divider circuit is connected to the first filter circuit and is used to divide the filtered electrical signal to obtain a sampling signal; The second filtering circuit is connected to the voltage divider circuit and is used for filtering the sampling signal to obtain the second signal.

5. The voltage-type controlled LLC protection circuit according to claim 4, characterized in that: The rectifier module includes: a full-bridge rectifier circuit, a half-wave rectifier circuit, or a full-wave rectifier circuit; The input end of the rectifier module is connected to the sampling circuit, and the output end of the rectifier module is connected to the voltage divider circuit.

6. The voltage-type controlled LLC protection circuit according to claim 4, characterized in that: The first filtering circuit includes: a first capacitor and a first resistor; The first end of the first capacitor and the first end of the first resistor are connected to the first output end of the rectifier module; The second end of the first capacitor and the second end of the first resistor are connected to the second output end of the rectifier module.

7. The voltage-type controlled LLC protection circuit according to claim 4, characterized in that: The voltage divider circuit comprises: a second resistor, a third resistor and a fourth resistor; The first output end of the rectifier module is connected to the first end of the second resistor; The second output end of the rectifier module is connected to the second end of the fourth resistor; The second end of the second resistor is connected to the first end of the third resistor, and a common end of the two serves as a first sampling end; The second end of the third resistor is connected to the first end of the fourth resistor, and a common end of the two serves as a second sampling end; The first sampling terminal is connected to the second sampling terminal, and a common terminal of the two is connected to the input terminal of the main control IC chip as a voltage output terminal.

8. The voltage-type controlled LLC protection circuit according to claim 7, characterized in that: The second filtering circuit includes: a second capacitor and a third capacitor; The first end of the second capacitor is connected to the first sampling end; The first end of the third capacitor is connected to the second sampling end, and the second end of the third capacitor is connected to the second end of the fourth resistor.

9. The voltage-type controlled LLC protection circuit according to any one of claims 1 to 8, characterized in that: Also includes: a first diode and a second diode; The anode of the first diode is connected to the first output terminal of the signal processing circuit, and the cathode of the first diode is connected to the voltage output terminal; An anode of the second diode is connected to the second output terminal of the signal processing circuit, and a cathode of the first diode is connected to the voltage output terminal.

10. A power supply, characterized in that: A protection circuit for a voltage-type controlled LLC comprising any one of claims 1 to 9.

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