An adaptive rectification control circuit and implementation method

Abstract

The application provides an adaptive rectification control circuit and an implementation method, which are suitable for a wide range of occasions, can effectively solve the problem of rectification loss, and make the circuit have the best efficiency in different working states; a transformer, a switch assembly and a current collection module are sequentially electrically connected; the current collection module detects and collects the current flowing through the switch assembly, and converts the current into a voltage signal; a comparison module is connected between the current collection module and a logic drive module, used for receiving the voltage signal output by the current collection module, comparing the received voltage value with a preset reference voltage, and outputting a level signal to the logic drive module according to the comparison result; the logic drive module is connected with the transformer, the switch assembly and the comparison module, used for generating a logic drive signal based on the signals output by the transformer and the comparison module received synchronously, and controlling the conduction or closing of the switch assembly according to the logic drive signal; the switch assembly comprises MOS tubes and diodes connected in parallel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a self-adaptive rectification control circuit and implementation method. BACKGROUND

[0002] In recent years, with the rapid growth of portable electronic products, people's requirements for the functions and performance of electronic products are constantly improving, especially in the current advocacy of energy saving and environmental protection, the high efficiency and low power consumption of electronic products become particularly important.

[0003] As an important part of electronic equipment, the conversion efficiency and standby power consumption of switching power supply products play a key role in the overall performance and energy saving and environmental protection performance of electronic equipment. Among them, the output rectification circuit part of the switching power supply generally adopts two ways, one is the ordinary diode rectification way, and the other is the synchronous rectification way; Among them, the diode rectification way has relatively large conduction voltage drop of diode itself, and the loss is large, which is suitable for small current occasions; And the synchronous rectification way uses MOSFET instead of diode, which has smaller conduction voltage drop and smaller conduction loss, which is suitable for occasions with large current.

[0004] At present, the synchronous rectification mode is mostly used, which can play a greater advantage in high-power occasions, but in actual application, the circuit load in many occasions is not always working in the state of large current and high power, and the circuit load will change. If the power supply works in the state of light load or even no load, at this time, due to the existence of negative current of synchronous rectification mode, the loss will increase and the efficiency will decrease when the circuit is in no load or light load state, that is, the power consumption of synchronous rectification mode will be significantly higher than that of ordinary diode rectification mode, which makes the switching power supply circuit not in the most ideal working state under different load conditions, which will inevitably reduce the low power consumption of electronic products, thereby affecting the standby power consumption or conversion efficiency of electronic products under light load. SUMMARY

[0005] In view of the above problems, the present application provides a self-adaptive rectification control circuit and implementation method, which is widely applicable and can effectively solve the rectification loss problem, so that the circuit is in the best state under different working conditions.

[0006] The technical scheme is as follows: a self-adaptive rectification control circuit, characterized by comprising a transformer, a switching component, a current acquisition module, a comparison module and a logic drive module.

[0007] Among them, the transformer, the switching component and the current acquisition module are electrically connected in sequence, the current acquisition module detects and acquires the current flowing through the switching component, and converts the current into a voltage signal;

[0008] The comparison module is connected between the current acquisition module and the logic drive module, and is configured to receive the voltage signal output by the current acquisition module, compare the received voltage value with a preset reference voltage, and output a level signal to the logic drive module according to a comparison result.

[0009] The logic drive module is connected with the transformer, the switch assembly and the comparison module, and is configured to generate a logic drive signal based on the signals output by the transformer and the comparison module, and control the switch assembly to be turned on or turned off according to the logic drive signal.

[0010] The switch assembly includes MOS tubes and diodes connected in parallel.

[0011] Further, the rectification control circuit further includes a control module, the comparison module has a reference input end and a signal input end, the reference input end of the comparison module is connected with the control module, so as to input the reference voltage value output by the control module, and the signal input end of the comparison module is configured to input the voltage signal output by the current acquisition module.

[0012] Further, the rectification control circuit further includes a voltage division unit composed of voltage division resistive elements, the voltage division unit forms the preset reference voltage by connecting the output voltage of the rectification control circuit, and sends the voltage to the comparison module.

[0013] Further, the rectification control circuit further includes a signal amplification module and a filter delay module.

[0014] The signal amplification module is connected between the current acquisition module and the comparison module, and is configured to amplify the voltage signal output by the current acquisition module and output the amplified voltage signal to the comparison module.

[0015] The filter delay module is connected between the comparison module and the logic drive module, and is configured to perform delay filtering on the level signal output by the comparison module.

[0016] Further, the logic drive module includes an AND gate, the output ends of the transformer and the filter delay module are respectively connected to two input ends of the AND gate, and the input end of the switch assembly is connected to the output end of the AND gate; the logic drive module generates a logic drive signal after performing AND operation on the output signals of the transformer and the filter delay module.

[0017] Further, the AND gate comprises AND gate IC1 and AND gate IC2; the MOS tube comprises MOS tube Q1 and MOS tube Q2; the diode comprises diode D1 and diode D2; one input end of the AND gate IC1 and the AND gate IC2 is connected with the output end of the filter delay module; the other input end of the AND gate IC1 and the AND gate IC2 is connected with the secondary winding of the transformer; the gate of the MOS tube Q1 is connected with the output end of the AND gate IC1; the gate of the MOS tube Q2 is connected with the output end of the AND gate IC2; the drain of the MOS tube Q1 and the anode of the diode D1 are both connected with one end of the secondary winding of the transformer; the source of the MOS tube Q2 and the anode of the diode D2 are both connected with the other end of the secondary winding of the transformer; the source of the MOS tube Q1 and the cathode of the diode D1 are both connected with the drain of the MOS tube Q2 and the cathode of the diode D2.

[0018] Further, the comparison module comprises comparator IC3, the non-inverting input end of the comparator IC3 is connected with the output end of the signal amplification module, the output end of the comparator IC3 is connected with the input end of the filter delay module, and the reference input end of the comparator IC3 is connected with the control module.

[0019] An adaptive rectification control implementation method applied to a switching power supply, characterized in that it comprises:

[0020] An electric current signal flowing through a switching component is acquired, and the electric current is converted into a voltage signal;

[0021] The voltage signal is judged against a preset reference voltage;

[0022] In response to the judgment result, a logic drive signal for turning on or off a MOS tube is generated, so as to realize adaptive switching between the switching power supply synchronous rectification mode and the diode rectification mode.

[0023] Further, when the voltage value received by the comparison module is less than the preset reference voltage, the logic drive module outputs a logic drive signal for turning off the MOS tube, the diode is turned on, and the switching power supply diode rectification mode is realized.

[0024] When the voltage value received by the comparison module is greater than the preset reference voltage, the logic drive module outputs a logic drive signal for turning on the MOS tube, and the switching power supply synchronous rectification mode is realized.

[0025] Further, when the voltage value received by the comparison module is less than the preset reference voltage, the comparison module outputs a low-level voltage signal.

[0026] When the voltage value received by the comparison module is greater than the preset reference voltage, the comparison module outputs a high-level voltage signal.

[0027] The present application has the beneficial effect that it judges the current signal flowing through the switch assembly with the preset reference voltage after collecting the current signal, generates the logic drive signal for turning on or turning off the MOS tube according to the judgment result, thereby controls the diode rectification mode in the no-load and light-load state, the synchronous rectification mode in the large current condition, realizes the adaptive switching of the rectification mode, and makes the rectification control circuit achieve the best working efficiency in different working states. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the structural block diagram of the present application;

[0029] Figure 2 is the circuit principle diagram of the present application. DETAILED DESCRIPTION

[0030] As shown in Figure 1 , Figure 2 the present application is an adaptive rectification control circuit, comprising a transformer B1, a switch assembly, a current collection module, a comparison module, a logic drive module;

[0031] Among them, the transformer B1, the switch assembly and the current collection module are sequentially electrically connected, the current collection module detects and collects the current flowing through the switch assembly, and converts the current into a voltage signal;

[0032] The comparison module is connected between the current collection module and the logic drive module, used for receiving the voltage signal output by the current collection module, comparing the received voltage value with the preset reference voltage, and outputting the level signal to the logic drive module according to the comparison result;

[0033] The logic drive module is connected with the transformer B1, the switch assembly and the comparison module, used for generating the logic drive signal based on the synchronously received signals output by the transformer B1 and the comparison module, and controlling the turn-on or turn-off of the switch assembly according to the logic drive signal;

[0034] The switch assembly comprises a MOS tube and a diode connected in parallel.

[0035] The rectification control circuit further comprises a control module, the control module adopts the existing control device, the comparison module has a reference input end and a signal input end, the reference input end of the comparison module is connected with the control module, used for inputting the reference voltage value output by the control module, and the signal input end of the comparison module is used for inputting the voltage signal output by the current collection module;

[0036] The rectification control circuit further comprises a voltage division unit composed of voltage division resistive elements, the voltage division unit inputs the output voltage of the rectification control circuit to form the preset reference voltage, and sends it into the comparison module;

[0037] That is, the preset reference voltage can be set by the control module, so as to change the different states of the comparator output under different current values, control the working mode of using diode rectification under no-load and light-load state, and use synchronous rectification under large current condition;

[0038] The preset reference voltage can also be formed by a voltage dividing unit composed of resistors R5 and R6.

[0039] The rectification control circuit further comprises a signal amplification module and a filter delay module.

[0040] The signal amplification module is connected between the current acquisition module and the comparison module, and is configured to amplify the voltage signal output by the current acquisition module and output the amplified voltage signal to the comparison module.

[0041] The filter delay module is connected between the comparison module and the logic drive module, and is configured to delay and filter the level signal output by the comparison module, so that the synchronous rectification circuit is closed under the non-stable load state in the power-on transient state, and the diode rectification circuit is used to work, thereby improving the stability of the circuit.

[0042] The logic drive module comprises an AND gate, the output ends of the transformer B1 and the filter delay module are respectively connected to the two input ends of the AND gate, and the input end of the switch assembly is connected to the output end of the AND gate; the logic drive module generates a logic drive signal after performing AND operation on the output signals of the transformer B1 and the filter delay module.

[0043] The non-inverting input end of the comparator IC3 is connected to the output end of the signal amplification module, the output end of the comparator IC3 is connected to the input end of the filter delay module, and the reference input end of the comparator IC3 is connected to the control module.

[0044] The connection of the rectification control circuit is as follows:

[0045] The MOS tube comprises MOS tubes Q1 and Q2, and the diode comprises diodes D1 and D2.

[0046] The rectification control circuit further comprises capacitors C1 and C2, MOS tubes Q3 and Q4, an inductor L1, and a resistor R1.

[0047] The current acquisition module comprises a sampling resistor R2.

[0048] The signal amplification module comprises an amplifier IC4 and resistors R3 and R4.

[0049] The comparison module comprises a comparator IC3 and resistors R5 to R8.

[0050] The filter delay module comprises a resistor R9 and a capacitor C3.

[0051] The logic driving module further comprises resistors R10 and R11, an AND gate IC1, and an AND gate IC2.

[0052] One end of a primary winding of a transformer B1 is connected to a positive input voltage +Vin of a rectification control circuit, the other end of the primary winding of the transformer B1 is connected to one end of a capacitor C1 and a drain of a MOS transistor Q4, the other end of the capacitor C1 is connected to a drain of a MOS transistor Q3, a source of the MOS transistor Q4 is connected to one end of a resistor R1, the other end of the resistor R1 is connected to a source of the MOS transistor Q3 and then connected to a negative input voltage -Vin of the rectification control circuit;

[0053] One end of a secondary winding of the transformer B1 is connected to one end of a resistor R10, a drain of a MOS transistor Q1, and a positive electrode of a diode D1, one of an input end of the AND gate IC1 and an input end of the AND gate IC2 is connected to one end of a resistor R7, one end of a resistor R9, and one end of a capacitor C3, the other end of the resistor R10 is connected to the other input end of the AND gate IC1, the other input end of the AND gate IC2 is connected to one end of a resistor R11, the other end of the resistor R11 is connected to the other end of the secondary winding of the transformer B1, one end of a resistor R2, a source of the MOS transistor Q2, and a positive electrode of a diode D2, a source of the MOS transistor Q1, a negative electrode of the diode D1, a drain of the MOS transistor Q2, a negative electrode of the diode D2, and one end of an inductor L1 are all connected, a gate of the MOS transistor Q1 is connected to an output end of the AND gate IC1, a gate of the MOS transistor Q2 is connected to an output end of the AND gate IC2, the other end of the inductor L1 is connected to one end of a capacitor C2, and the connection point is used as an output voltage Vout of the rectification control circuit, the other end of the capacitor C2 is connected to the other end of the resistor R2 and then grounded.

[0054] The other end of the resistor R3 is connected to one end of a resistor R4 and an inverting input end of an amplifier IC4, a non-inverting input end of the amplifier IC4 is grounded, the other end of the resistor R4 is connected to an output end of the amplifier IC4 and then connected to a non-inverting input end of a comparator IC3, one end of resistors R5, R6, and R8 is connected to an inverting input end of the comparator IC3, the other end of the resistor R8 is connected to a control module, the output voltage Vout is connected to the other end of the resistor R6 and the other end of the resistor R7 and then connected to a reference input end of the comparator IC3, and a reference input end of the amplifier IC4 is connected to the output voltage Vout; the other end of the resistor R9 is connected to an output end of the comparator IC3, and the other end of the capacitor C3 is grounded.

[0055] An adaptive rectification control implementation method applied to a switching power supply, comprising:

[0056] An electric current signal flowing through a switching assembly is obtained, and the electric current is converted into a voltage signal;

[0057] The voltage signal is compared with a preset reference voltage.

[0058] In response to the judgment result, a logic drive signal for turning on or turning off the MOS tube is generated to realize adaptive switching of the synchronous rectification and diode rectification working modes of the switching power supply.

[0059] If the voltage value received by the comparison module is less than the preset reference voltage, the comparison module outputs a low voltage signal, the logic drive module outputs a logic drive signal for turning off the MOS tube, the diode is turned on, and the diode rectification working mode of the switching power supply is realized.

[0060] If the voltage value received by the comparison module is greater than the preset reference voltage, the comparison module outputs a high voltage signal, the logic drive module outputs a logic drive signal for turning on the MOS tube, and the synchronous rectification working mode of the switching power supply is realized.

[0061] The working principle of the present application is that the sampling resistor R2 collects the output current to detect the size of the current in the rectification control circuit, converts the output current into a voltage signal, and sends the voltage signal into a signal amplification module for amplification, then outputs the amplified signal to a comparison module and compares it with a preset reference voltage to determine the level state of the output voltage of the comparator IC3; that is, when the output current is small, the amplified voltage signal is less than the preset reference voltage, the comparator IC3 outputs a low level; when the output current becomes large, until the voltage signal is greater than the preset reference voltage, the comparator IC3 flips, and the comparator IC3 outputs a high level; one input end of the AND gate IC1 and the AND gate IC2 receives a driving signal from the transformer B1, and the other input end receives a signal output from the comparator IC3 and filtered by a filtering and delay module, after the two signals are subjected to AND operation, a logic drive signal is generated to control the on-off of the MOS tube.

[0062] In summary, when the output current is small, the AND gate IC1 and the AND gate IC2 output a low level, the synchronous rectification MOS tube is turned off, and the rectification control circuit is in the diode rectification working mode.

[0063] When the output current becomes large and exceeds the preset reference voltage, the output signal of the AND gate IC1 and the AND gate IC2 depends on the driving signal from the transformer B1, at this time, the synchronous rectification circuit works, and since the on-off impedance of the MOS tube in the synchronous rectification circuit is small, the MOS tubes Q1 and Q2 are turned on, and the rectification control circuit is in the synchronous rectification working mode.

[0064] In the application, through the current sampling module, comparison module, double signal acquisition logic drive module and the like, the synchronous rectification circuit failure caused by the start transient current impact can be effectively detected and avoided, the system reliability is improved, the switching threshold voltage of the synchronous rectification and the diode rectification can be flexibly adjusted to control the working time of the synchronous rectification and the ordinary diode rectification, the rectification circuit can achieve the best working efficiency in different working states, the precise control is realized, and the cost is reduced.

[0065] It is apparent for a person skilled in the art that the application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and not limiting in any way, the scope of the application being defined by the claims appended hereto rather than the above description, and all changes falling within the meaning and range of equivalency of the elements of the claims are therefore intended to be embraced therein. Any reference signs in the claims should not be considered as limiting the claims involved.

[0066] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment according to the present specification need necessarily contain all features described herein. The specification is only intended to cover the generic scope of the application claimed herein and is not intended to be limited to the specific embodiments described herein.

Claims

1. An adaptive rectifier control circuit, characterized by: The application relates to a rectification control circuit, which comprises a transformer, a switch assembly, a current collection module, a comparison module and a logic drive module. The transformer, the switch assembly and the current collection module are electrically connected in sequence, the current collection module detects and collects the current flowing through the switch assembly, and converts the current into a voltage signal; The comparison module is connected between the current collection module and the logic drive module, receives the voltage signal output by the current collection module, compares the received voltage value with a preset reference voltage, and outputs a level signal to the logic drive module according to the comparison result; The logic drive module is connected with the transformer, the switch assembly and the comparison module, generates a logic drive signal based on the signals output by the transformer and the comparison module, and controls the conduction or closing of the switch assembly according to the logic drive signal; The switch assembly comprises MOS tubes and diodes connected in parallel. The rectification control circuit further comprises a voltage division unit composed of voltage division resistive elements, which forms the preset reference voltage by connecting the output voltage of the rectification control circuit and sends the voltage into the comparison module; the rectification control circuit further comprises a signal amplification module and a filter delay module; The signal amplification module is connected between the current collection module and the comparison module, amplifies the voltage signal output by the current collection module and then outputs the signal to the comparison module; The filter delay module is connected between the comparison module and the logic drive module, and is used for delaying and filtering the level signal output by the comparison module; The logic drive module comprises an AND gate, the output ends of the transformer and the filter delay module are respectively connected to the two input ends of the AND gate, and the input end of the switch assembly is connected to the output end of the AND gate; the logic drive module generates a logic drive signal after performing AND operation on the output signals of the transformer and the filter delay module; The AND gate comprises AND gate IC1 and AND gate IC2; the MOS tubes comprise MOS tube Q1 and MOS tube Q2, and the diodes comprise diode D1 and diode D2; one input end of the AND gate IC1 and the AND gate IC2 is connected to the output end of the filter delay module, and the other input end of the AND gate IC1 and the AND gate IC2 is connected to the secondary winding of the transformer; the gate of the MOS tube Q1 is connected to the output end of the AND gate IC1, the gate of the MOS tube Q2 is connected to the output end of the AND gate IC2, one end of the secondary winding of the transformer is connected to the drain of the MOS tube Q1 and the anode of the diode D1, the other end of the secondary winding of the transformer is connected to the source of the MOS tube Q2 and the anode of the diode D2, and the source of the MOS tube Q1, the cathode of the diode D1, the drain of the MOS tube Q2 and the cathode of the diode D2 are connected.

2. An adaptive rectifier control circuit according to claim 1, characterized in that: The rectification control circuit further comprises a control module, the comparison module has a reference input end and a signal input end, the reference input end of the comparison module is connected with the control module, for inputting the reference voltage value outputted by the control module, and the signal input end of the comparison module is used for inputting the voltage signal outputted by the current collection module.

3. An adaptive rectifier control circuit according to claim 1, wherein: The comparison module comprises a comparator IC3, the noninverting input end of the comparator IC3 is connected with the output end of the signal amplification module, the output end of the comparator IC3 is connected with the input end of the filter delay module, and the reference input end of the comparator IC3 is connected with the control module.

4. A method for implementing adaptive rectification control, applied to a switching power supply, characterized in that: The method comprises the following steps: acquiring a current signal flowing through the switch assembly and converting the current into a voltage signal; judging the voltage signal and a preset reference voltage; in response to the judging result, generating a logic drive signal for turning on or off the MOS tube, so as to realize adaptive switching of the synchronous rectification and the diode rectification working mode of the switching power supply; if the voltage value received by the comparison module is less than the preset reference voltage, the logic drive module outputs a logic drive signal for turning off the MOS tube, the diode is turned on, and the diode rectification working mode of the switching power supply is realized; if the voltage value received by the comparison module is greater than the preset reference voltage, the logic drive module outputs a logic drive signal for turning on the MOS tube, and the synchronous rectification working mode of the switching power supply is realized; if the voltage value received by the comparison module is less than the preset reference voltage, the comparison module outputs a low-level voltage signal; if the voltage value received by the comparison module is greater than the preset reference voltage, the comparison module outputs a high-level voltage signal.

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