A method and system for zero current detection and regulation

Abstract

The present invention discloses a zero current detection and regulation system, comprising a power stage circuit, a comparison threshold circuit, a zero-crossing detection circuit and a switch power supply control circuit connected in sequence, wherein the switch power supply control circuit is also connected to the power stage circuit, the comparison threshold circuit is also connected to a compensation circuit, the compensation circuit is also connected to a sampling circuit, and the sampling circuit is used to collect input voltage and / or output voltage and / or temperature signals of the power stage circuit. The present invention utilizes the compensation circuit to collect the input voltage and / or output voltage and / or temperature changes of the power stage circuit and inputs the compensation signal to the comparison threshold circuit, automatically adjusts the threshold of the comparison threshold circuit and the zero current speed and accuracy of the zero-crossing detection circuit, and can also compensate for the zero current detection deviation caused by the influence of the input voltage and / or output voltage and / or temperature changes of the power stage circuit on the detection speed of the zero-crossing detection circuit and the internal resistance of the power tube of the power stage circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supply converters, and in particular to a method and system for zero current detection and regulation. Background Art

[0002] The common point of synchronous rectification switching power converters is that the freewheeling switch tube is used to replace the freewheeling diode to reduce power loss and improve conversion efficiency. When the switching power converter is under heavy load, it is in the inductor current continuous mode (CCM). When the load is light, the duty cycle decreases, the inductor current decreases, and it is in the inductor current discontinuous mode (DCM). In order to prevent the inductor current from backflowing, which leads to the decrease in the conversion efficiency of the synchronous rectification switching power converter under light load, the freewheeling switch needs to be turned off when the current drops to zero. When there is current flowing through the freewheeling switch tube, due to the on-resistance of the freewheeling switch tube, there is a voltage difference between the source and drain of the freewheeling switch tube. The voltage difference is proportional to the current flowing. Once the current drops to zero, the source-drain voltage difference of the freewheeling switch tube also drops to zero. Therefore, the traditional method of the existing synchronous rectification switching power converter is to use a comparator to compare the voltage difference between the source and drain of the freewheeling switch tube. Once it is found that the voltage difference between the source and drain of the power tube drops to zero, it is considered that the current is zero, and the freewheeling power tube is immediately turned off. At the same time, due to the comparison speed problem of the comparator, an advance threshold circuit is generally added to the source-drain voltage difference to allow the comparator to perform comparison in advance, ensuring that the inductor current is exactly zero when the comparator outputs a comparison signal.

[0003] However, due to the popularity of fast charging technology for electronic devices such as mobile phones, the input and output voltage ranges of switching power converters used in the field of fast charging products vary greatly. The inductor discharge slope is proportional to the difference between the input and output. Due to the change in the input and output voltage of the converter, the speed of current drop varies greatly. Therefore, under different input and output conditions, if the comparison speed of the comparison threshold circuit and the comparator is fixed, it will cause a large deviation in the zero current detection result with the change of input and output. When the switching power supply charges ordinary devices, the output voltage is 5V. When the switching power supply charges fast charging devices, the output voltage may be 9V, 12V or even as high as 20V. For this traditional approach, if the comparison speed of the comparison threshold circuit and the zero-crossing comparator meets the output of 5V, when the current is just zero, the comparator outputs a zero current signal, then when the output is 9V or 12V, due to the faster current drop speed, when the zero-crossing comparator outputs a zero current signal, the inductor current value has become negative, resulting in efficiency loss. At the same time, the switching power converter has the problem of self-heating. Due to the heating, the speed of the comparator will change, which will cause a deviation in zero current detection. Similarly, the internal resistance of the power tube is different at different temperatures, so at the same current, the voltage difference across the power tube will change, which will also cause deviation in the zero current detection result. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method and system for zero current detection and adjustment, which can automatically adjust the system's comparison threshold and / or comparator speed zero current detection speed and accuracy according to system temperature changes and / or voltage input changes and / or voltage output changes.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a zero current detection and regulation system, including a power stage circuit, a comparison threshold circuit, a zero-crossing detection circuit and a switching power supply control circuit connected in sequence, the switching power supply control circuit is also connected to the power stage circuit, the comparison threshold circuit is also connected to a compensation circuit, the compensation circuit is also connected to a sampling circuit, and the sampling circuit is used to collect input voltage and / or output voltage and / or temperature signals of the power stage circuit.

[0006] Furthermore, the compensation circuit is also connected to the zero-crossing detection circuit to change the bias current of the zero-crossing detection circuit.

[0007] Furthermore, the sampling circuit includes an input voltage sampling unit, an output voltage sampling unit and a temperature detection unit, the input end of the input voltage sampling unit is connected to the power supply end of the power stage circuit, the output end of the input voltage sampling unit is connected to the first signal acquisition end of the compensation circuit, the input end of the output voltage sampling unit is connected to the output end of the power stage circuit, the output end of the output voltage sampling unit is connected to the second signal acquisition end of the compensation circuit, and the output end of the temperature detection unit is connected to the third signal acquisition end of the compensation circuit.

[0008] Furthermore, the sampling circuit includes an input voltage sampling unit and a temperature detection unit, the input end of the input voltage sampling unit is connected to the power supply end of the power stage circuit, the output end of the input voltage sampling unit is connected to the first signal acquisition end of the compensation circuit, and the output end of the temperature detection unit is connected to the third signal acquisition end of the compensation circuit.

[0009] Furthermore, the sampling circuit includes an output voltage sampling unit and a temperature detection unit, the input end of the output voltage sampling unit is connected to the output end of the power stage circuit, the output end of the output voltage sampling unit is connected to the second signal acquisition end of the compensation circuit, and the output end of the temperature detection unit is connected to the third signal acquisition end of the compensation circuit.

[0010] Furthermore, the sampling circuit includes an input voltage sampling unit and an output voltage sampling unit, the input end of the input voltage sampling unit is connected to the power supply end of the power stage circuit, the output end of the input voltage sampling unit is connected to the first signal acquisition end of the compensation circuit, the input end of the output voltage sampling unit is connected to the output end of the power stage circuit, and the output end of the output voltage sampling unit is connected to the second signal acquisition end of the compensation circuit.

[0011] A method for zero current detection and regulation, characterized in that it comprises the following steps:

[0012] S1, the acquisition circuit acquires the input voltage and / or output voltage and / or temperature signals of the power stage circuit in real time and feeds them back to the compensation circuit respectively;

[0013] S2, the compensation circuit converts at least one signal fed back by the acquisition circuit into a current signal and superimposes the signals to form a compensation signal, and inputs the compensation signal to the comparison threshold circuit;

[0014] S3, the comparison threshold circuit collects the voltage difference signal in the power stage circuit and superimposes it with the compensation signal to form a comparison threshold signal, and the comparison threshold circuit simultaneously inputs the comparison threshold signal and the reference signal to the zero-crossing detection circuit;

[0015] S4, the zero-crossing detection circuit compares the comparison threshold signal output by the comparison threshold circuit with the reference signal and outputs the comparison signal to the switching power supply control circuit;

[0016] S5. The switching power supply control circuit adjusts the duty cycle of the output signal of the power stage circuit according to the comparison signal.

[0017] Furthermore, the step S2 further includes the following steps:

[0018] S2a, the compensation signal of the compensation circuit is input to the zero-crossing detection circuit to adjust the detection speed of the zero-crossing detection circuit.

[0019] Furthermore, the voltage difference signal in step S3 is the voltage difference between the source and the drain of the freewheeling switch tube M2 in the power stage circuit.

[0020] Furthermore, the specific method for adjusting the duty cycle signal of the power stage circuit output signal in step S5 is: the switching power supply control circuit controls the on or off time of the main switch tube M1 and the freewheeling switch tube M2 in the power circuit according to the comparison signal, so as to adjust the duty cycle of the power stage circuit output signal.

[0021] The beneficial effects of the present invention are as follows: the present invention can automatically adapt to input and output changes, utilize the compensation circuit to collect the input voltage and / or output voltage and / or temperature changes of the power stage circuit and input the compensation signal to the comparison threshold circuit, and can automatically adjust the threshold of the comparison threshold circuit and the zero current speed and accuracy of the zero-crossing detection circuit, and at the same time can compensate for the zero current detection deviation caused by the influence of the input voltage and / or output voltage and / or temperature changes of the power stage circuit on the detection speed of the zero-crossing detection circuit and the internal resistance of the power tube of the power stage circuit; since all the synchronous rectification switching power supply converters of the current topology structure adopt the freewheeling switch to replace the freewheeling diode, the circuit can be conveniently applied to synchronous rectification switching power supply converters of various topology structures such as DC-DC switching power supply and DC-AC switching power supply to improve the efficiency of the switching power supply under light load. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 It is a principle block diagram of a preferred embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the main flow of the zero current detection and regulation method of the present invention;

[0025] Figure 3 is a circuit structure diagram of a first embodiment of the present invention;

[0026] Figure 4 is a circuit structure diagram of an input voltage sampling unit in a first embodiment of the present invention;

[0027] Figure 5 is a circuit structure diagram of a compensation circuit in a first embodiment of the present invention;

[0028] Figure 6 is a circuit structure diagram of a comparison threshold circuit in a first embodiment of the present invention;

[0029] Figure 7 is a circuit schematic diagram of a switching power supply control circuit in a first embodiment of the present invention;

[0030] Figure 8 is a circuit structure diagram of a second embodiment of the present invention;

[0031] Fig. 9 is a circuit structure diagram of a comparison threshold circuit in a second embodiment of the present invention;

[0032] Fig.10 is a circuit structure diagram of a compensation circuit in a second embodiment of the present invention;

[0033] Fig.11 It is a third circuit structure diagram of the compensation circuit of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention more clear, the concept, specific structure and technical effects of the present invention will be clearly and completely described below in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0035] Reference Figure 1 , is a preferred implementation, a zero current detection and regulation system, comprising a power stage circuit 1, a comparison threshold circuit 2, a zero-crossing detection circuit 3 and a switching power supply control circuit 4 connected in sequence, the switching power supply control circuit 4 is also connected to the power stage circuit 1, the comparison threshold circuit 2 is also connected to a compensation circuit 5, the compensation circuit 5 is also connected to a sampling circuit 6, the sampling circuit 6 is used to collect input voltage and / or output voltage and / or temperature signals of the power stage circuit 1.

[0036] Preferably, the compensation circuit 5 is also connected to the zero-crossing detection circuit 3 to change the bias current of the zero-crossing detection circuit 3 to adjust the detection speed of the zero-crossing detection circuit 3 .

[0037] The power stage circuit 1 at least includes a main switch tube M1 and a freewheeling switch tube M2. The duty cycle of the output signal of the power stage circuit 1 is adjusted by using two power MOS tubes with extremely low on-resistance and according to the control signal of the switching power supply control circuit 4. It is mainly used for AC-DC conversion or DC boost or DC step-down conversion.

[0038] The sampling circuit 6 includes an input voltage sampling unit 61 and / or an output voltage sampling unit 62 and / or a temperature detection unit 63, the input end of the input voltage sampling unit 61 is connected to the power supply end of the power stage circuit 1, the output end of the input voltage sampling unit 61 is connected to the first signal acquisition end of the compensation circuit 5, the input end of the output voltage sampling unit 62 is connected to the output end of the power stage circuit 1, the output end of the output voltage sampling unit 62 is connected to the second signal acquisition end of the compensation circuit 5, and the output end of the temperature detection unit 63 is connected to the third signal acquisition end of the compensation circuit 5.

[0039] The input voltage sampling unit 61 is used to collect the input voltage of the power stage circuit 1 and send the input voltage signal to the compensation circuit 5 .

[0040] The output voltage sampling unit 62 is used to collect the output voltage of the power stage circuit 1 and send the output voltage signal to the compensation circuit 5 .

[0041] The temperature detection unit 63 is used to collect the temperature of the power stage circuit 1 and send a temperature signal to the compensation circuit 5 .

[0042] Among them, if the input voltage of the power stage circuit 1 remains unchanged or the variation range is not large, the input voltage sampling unit 61 may not be used; if the output voltage of the power stage circuit 1 remains unchanged or the variation range is not large, the output voltage sampling unit 62 may not be used; if the temperature variation range of the power stage circuit 1 is not large, the temperature detection unit 63 may not be used.

[0043] The switching power supply control circuit 4 controls the working states of the main switch tube M1 and the freewheeling switch tube M2 of the power stage circuit 1 according to the comparison signal output by the zero-crossing detection circuit 3, thereby adjusting the duty cycle of the main switch tube M1 and the freewheeling switch tube M2 to achieve the stability of the output signal and the duty cycle of the power stage circuit 1.

[0044] The compensation circuit 5 receives relevant signals such as the real-time input voltage signal of the power stage circuit 1 and / or the real-time output voltage signal of the power stage circuit 1 and / or the real-time temperature signal of the power stage circuit 1 and outputs the compensation signal as a compensation signal, and inputs the compensation signal to the comparison threshold circuit 2, thereby adjusting the voltage comparison threshold of the zero-crossing detection circuit 3.

[0045] The comparison threshold circuit 2 superimposes the compensation signal input by the compensation circuit 5 with the voltage difference signal collected between the source and drain of the freewheeling switch tube M2 to form a comparison threshold signal, and outputs a real-time comparison threshold signal to the zero-crossing detection circuit 3, thereby achieving the purpose of adjusting the comparison threshold of the zero-crossing detection circuit 3.

[0046] The zero-crossing detection circuit 3 mainly adopts a zero-crossing comparator U1 as a threshold comparison processor, wherein the non-inverting input terminal of the zero-crossing comparator U1 is connected to the first input terminal of the comparison threshold circuit 2, and the inverting input terminal of the zero-crossing comparator U1 is connected to the second output terminal of the comparison threshold circuit 2, wherein the bias current adjustment input terminal of the zero-crossing comparator U1 can also be connected to the output terminal of the compensation circuit 5, that is, the compensation signal is also sent to the zero-crossing detection circuit 3, so as to adjust the detection speed of the zero-crossing detection circuit 3 while adjusting the comparison threshold of the zero-crossing detection circuit 3, and the zero-crossing comparator U1 compares the input signals of the non-inverting input terminal and the inverting input terminal and outputs a comparison signal, and feeds the comparison signal back to the switching power supply control circuit 4.

[0047] Reference Figure 2 , which is the main flow chart of the present invention, a method for zero current detection and regulation, comprising the following steps:

[0048] S1, the acquisition circuit 6 acquires the input voltage and / or output voltage and / or temperature signals of the power stage circuit 1 in real time and feeds them back to the compensation circuit 5 respectively;

[0049] S2, the compensation circuit 5 converts at least one signal fed back by the acquisition circuit 6 into a current signal and superimposes the signals to form a compensation signal, and inputs the compensation signal to the comparison threshold circuit 2;

[0050] S3, the comparison threshold circuit 2 collects the voltage difference signal in the power stage circuit 1 and superimposes it with the compensation signal to form a comparison threshold signal, and the comparison threshold circuit 2 simultaneously inputs the comparison threshold signal and the reference signal to the zero-crossing detection circuit 3;

[0051] S4, the zero-crossing detection circuit 3 compares the comparison threshold signal output by the comparison threshold circuit 2 with the reference signal and outputs the comparison signal to the switching power supply control circuit;

[0052] S5. The switch power supply control circuit 4 adjusts the duty cycle of the output signal of the power stage circuit 1 according to the comparison signal.

[0053] Preferably, the step S2 further includes the following steps:

[0054] S2a, the compensation signal of the compensation circuit 5 is input to the zero-crossing detection circuit 3 to adjust the detection speed of the zero-crossing detection circuit 3.

[0055] Preferably, the voltage difference signal in step S3 is the voltage difference between the source and the drain of the freewheeling switch tube M2 in the power stage circuit 1 .

[0056] Preferably, the specific method for adjusting the duty cycle signal of the output signal of the power stage circuit 1 in step S5 is: the switching power supply control circuit 4 controls the on or off time of the main switch tube M1 and the freewheeling switch tube M2 in the power circuit 1 according to the comparison signal, so as to adjust the duty cycle of the output signal of the power stage circuit 1.

[0057] Reference Figure 3 , is the first embodiment, which is an implementation mode of the present invention applied in a boost DC-DC converter. In the first implementation mode, the sampling circuit 6 includes an input voltage sampling unit 61, an output voltage sampling unit 62 and a temperature detection unit 63. The input end of the input voltage sampling unit 61 is connected to the power supply end of the power stage circuit 1, the output end of the input voltage sampling unit 61 is connected to the first signal acquisition end of the compensation circuit 5, the input end of the output voltage sampling unit 62 is connected to the output end of the power stage circuit 1, the output end of the output voltage sampling unit 62 is connected to the second signal acquisition end of the compensation circuit 5, and the output end of the temperature detection unit 63 is connected to the third signal acquisition end of the compensation circuit 5.

[0058] In the first embodiment, the power stage circuit 1 includes a main switch tube M1, a freewheeling switch tube M2, an inductor L1 and a capacitor C1, wherein the main switch tube M1 and the freewheeling switch tube M2 are both field effect transistors.

[0059] Among them, one end of the inductor L1 is connected to the power supply end of the power stage circuit 1, and the other end is respectively connected to the drain of the main switch tube M1 and the source of the freewheeling switch tube M2, the gate of the main switch tube M1 is connected to the switch power control circuit 4, the source of the main switch tube M1 is grounded, the gate of the freewheeling switch tube M2 is connected to the switch power control circuit, the source of the freewheeling switch tube M2 is connected to the second input end of the comparison threshold circuit 2, the drain of the freewheeling switch tube M2 is respectively connected to one end of the capacitor C1, the output end of the power stage circuit 1 and the third input end of the comparison threshold circuit 2, and the other end of the capacitor C1 is grounded;

[0060] Preferably, reference Figure 4, is the actual circuit structure of the input voltage sampling unit 61 in the first embodiment, the input voltage sampling unit 61 includes a voltage dividing resistor R3, a voltage dividing resistor R4, a resistor R5, an operational amplifier U2, a seventh NMOS tube MN7 and a second PMOS type mirror current circuit composed of a third PMOS tube MP3 and a fourth PMOS tube MP4. One end of the voltage dividing resistor R3 serves as the input end of the input voltage sampling unit 61 and is connected to the power supply end of the power stage circuit 1. The other end of the voltage dividing resistor R3 is simultaneously connected to one end of the voltage dividing resistor R4 and the positive input end of the operational amplifier. The other end of the voltage dividing resistor R4 is grounded. The negative input end of the operational amplifier U2 is connected to the ground. The output end of the operational amplifier U2 is connected to the gate of the seventh NMOS tube, wherein the other end of the resistor R5 is grounded, and the drain of the seventh NMOS tube is connected to the drain of the third PMOS tube MP3, wherein the gate and the drain of the third PMOS tube MP3 are short-circuited, and the sources of the third PMOS tube MP3 and the fourth PMOS tube MP4 are connected to the power supply Vcc, and the gate of the third PMOS tube MP3 is connected to the gate of the fourth PMOS tube MP4, and the drain of the fourth PMOS tube MP4 serves as the output end of the input voltage sampling unit 61 and is connected to the input voltage sampling end of the compensation circuit 5.

[0061] In this embodiment, the circuit structures of the input voltage sampling unit 61 and the output voltage sampling unit 62 are the same, the difference is that the input end of the output voltage sampling unit 62 is connected to the output end of the power stage circuit 1, and the output end of the output voltage sampling unit 62 is connected to the output voltage sampling end of the compensation circuit 5.

[0062] The operational amplifier U2 and the seventh NMOS tube in the input voltage sampling unit 61 and the output voltage sampling unit 62 form a feedback network. Through the feedback, the voltages at the positive input terminal and the negative input terminal of the operational amplifier U2 are equal, so that the voltage of the resistor R5 is Therefore, the current on resistor R5 is The second PMOS type mirror current circuit is used to make the drain of the fourth PMOS tube serve as the output terminal. The voltage signal is converted into a current signal by the mirror current source, which is beneficial to the processing of the compensation circuit 5 , simplifies the circuit structure of the compensation circuit 5 , and is beneficial to simplifying the circuit cost.

[0063] The temperature detection unit 63 can use a PTAT current source to collect the real-time temperature value of the power stage circuit 1, and output a corresponding current signal to the compensation circuit 5 based on the real-time temperature signal. The temperature detection unit 63 can also use an NTC thermistor to collect the real-time temperature of the power stage circuit 1, and also output a corresponding current signal to the compensation circuit 5 based on the real-time temperature signal.

[0064] Preferably, reference Figure 5 , is a circuit structure connection diagram of the compensation circuit 5 in the first embodiment, wherein the compensation circuit 5 comprises a first PMOS type mirror current circuit, a first NMOS type mirror current circuit, a second NMOS type mirror current circuit and a third NMOS type mirror current circuit, wherein the input end of the first PMOS type mirror current circuit is connected to the output end of the first NMOS type mirror current circuit, the output end of the first PMOS type mirror current circuit serves as the output end of the compensation circuit 5 and is simultaneously connected to the first input end of the comparison threshold circuit 2, the output end of the second NMOS type mirror current circuit and the output end of the third NMOS type mirror current circuit, the input end of the first NMOS type mirror current circuit serves as the first signal acquisition end of the compensation circuit 5 and is connected to the output end of the output voltage sampling unit 62, the input end of the second NMOS type mirror current circuit serves as the third signal acquisition end of the compensation circuit 5 and is connected to the output end of the temperature detection unit 63, and the input end of the third NMOS type mirror current circuit serves as the second signal acquisition end of the compensation circuit 5 and is connected to the output end of the input voltage sampling unit 61.

[0065] In a first embodiment, the first PMOS type mirror current circuit uses a first PMOS tube MP1 and a second PMOS tube MP2 to form a mirror current circuit, the first NMOS type mirror current circuit uses a first NMOS tube MN1 and a second NMOS tube MN2 to form a mirror current circuit, the second NMOS type mirror current circuit uses a third NMOS tube MN3 and a fourth NMOS tube MN4 to form a mirror current circuit, and the third NMOS type mirror current circuit uses a fifth NMOS tube MN5 and a sixth NMOS tube MN6 to form a mirror current circuit; wherein the gate and drain of the first PMOS tube MP1 are short-circuited, the source of the first PMOS tube MP1 and the source of the second PMOS tube MP2 are connected to the power supply Vcc, and the gate of the first PMOS tube MP1 is connected to the gate of the second PMOS tube MP2, the drain of the second PMOS tube MP2 serves as the output end of the supplementary circuit and is connected to the drain of the fourth NMOS tube MN4 and the drain of the sixth NMOS tube MN6, and the first PMOS tube MP1 is short-circuited to the drain of the first PMOS tube MP1 and the source of the second PMOS tube MP2. The source of the first NMOS tube MN1 is connected to the drain of the second NMOS tube MN2; the gate and drain of the first NMOS tube MN1 are short-circuited, the gate of the first NMOS tube MN1 is connected to the gate of the second NMOS tube MN2, and the drain of the first NMOS tube MN1 is connected to the output end of the output voltage sampling unit 62; the gate and drain of the third NMOS tube MN3 are short-circuited, the gate of the third NMOS tube MN3 is connected to the gate of the fourth NMOS tube MN4, and the drain of the third NMOS tube MN3 is connected to the output end of the temperature detection unit 63; the gate and drain of the fifth NMOS tube MN5 are short-circuited, the gate of the fifth NMOS tube MN5 is connected to the gate of the sixth NMOS tube MN6, and the drain of the fifth NMOS tube MN5 is connected to the output end of the input voltage sampling unit 61; wherein the source of the first NMOS tube MN1, the source of the second NMOS tube MN2, the source of the third NMOS tube MN3, the source of the fourth NMOS tube MN4, the source of the fifth NMOS tube MN5, and the source of the sixth NMOS tube MN6 are all grounded.

[0066] The working principle of the compensation circuit 5 is that the drain of the first NMOS tube MN1 receives the output current signal Iouts of the output voltage sampling unit 62, the drain of the third NMOS tube MN3 receives the output current signal Iptat of the temperature detection unit 63, and the drain of the fifth NMOS tube MN5 receives the output current signal Iins of the input voltage sampling unit 61. By utilizing the principle of each group of mirror current circuits, the output terminal Icomp of the compensation circuit 5 can be made to be Iouts+Iptat+Iins, that is, a compensation current that compensates the real-time input and output voltage signals and the real-time temperature signal of the power stage circuit 1, that is, a compensation signal, is obtained, so that the output terminal Icomp of the compensation circuit 5 changes with the input and output voltage and temperature of the power stage circuit 1, and can offset the influence of the temperature, input voltage and output voltage of the power stage circuit 1 on the zero current detection.

[0067] Preferably, reference Figure 6 , is a circuit structure connection diagram of the comparison threshold circuit 2 in the first embodiment, the comparison threshold circuit 2 includes a comparison resistor Rcomp and a current source, one end of the comparison resistor Rcomp is connected to the source of the freewheeling switch tube M2, and the other end is used as the first output end of the comparison threshold circuit 2 and is respectively connected to the output end of the compensation circuit 5, the output end of the current source and the second input end of the zero-crossing detection circuit 3, the second output end of the comparison threshold circuit 2 is connected to the first input end of the zero-crossing detection circuit 3, the first output end of the comparison threshold circuit 2 is connected to the first input end of the comparison threshold circuit 2, and the comparison threshold circuit 2 is connected to the first input end of the comparison threshold circuit 2. The second output terminal of the comparison threshold circuit 2 is connected to its third input terminal; by using a simple resistor superposition method, an advance threshold, i.e., a compensation signal, can be conveniently superimposed on the voltage difference signal between the source and drain of the freewheeling switch tube M2. At the same time, the compensation current Icomp, i.e., the compensation signal, output by the compensation circuit 5 can also be conveniently superimposed on the voltage difference signal between the source and drain of the freewheeling switch tube M2, that is, the compensation signal and the voltage difference signal are superimposed and sent to the comparison threshold circuit 2, thereby offsetting the input and output voltage changes of the power stage circuit 1 and the slope of the signal changing with time caused by temperature changes. In this embodiment, the first output terminal of the comparison threshold circuit 2 outputs a reference signal, and the second output terminal of the comparison threshold circuit 2 outputs a comparison threshold signal.

[0068] At the same time, the output current Icomp of the compensation circuit 5, i.e., the compensation signal, can also be transmitted to the zero-crossing comparator U1. By changing the bias current of the zero-crossing comparator U1, the speed of the zero-crossing comparator U1 is changed, thereby offsetting the effect of temperature change on the speed of the zero-crossing comparator U1.

[0069] Preferably, reference Figure 7In the first embodiment, the switching power supply control circuit 4 includes a signal sampling unit, a reference voltage source, a loop control unit, a control logic unit and a power switch tube driving unit, wherein the signal sampling unit includes a voltage dividing resistor R1 and a voltage dividing resistor R2, wherein one end of the voltage dividing resistor R1 is connected to the output end Vout1 of the zero-crossing detection circuit 3, the other end of the voltage dividing resistor R1 is simultaneously connected to the input end of the loop modulation circuit and one end of the voltage dividing resistor R2, and the other end of the voltage dividing resistor R2 is grounded, the reference voltage source outputs a reference voltage signal to the loop control unit, the loop control unit compares the voltage dividing signal of the signal sampling unit with the reference voltage signal, and amplifies the error between the voltage dividing signal and the reference voltage signal, generates a loop adjustment signal, and transmits the loop adjustment signal to the control logic unit, the control logic unit outputs different control logic signals according to the loop adjustment signal and transmits them to the power switch tube driving unit, and controls the conduction or cutoff of the main switch tube M1 and the freewheeling switch tube M2 respectively through the power switch driving stage circuit.

[0070] refer to Figure 8 , is a second embodiment, which is an implementation mode of the present invention applied to a step-down DC-DC converter. In this embodiment, since the rate of change of the inductor current of the step-down DC-DC converter is only related to the output voltage but not to the input voltage, the difference between the second embodiment and the first embodiment is that the input voltage sampling unit is removed, and only the change of the output voltage and the temperature change of the power stage circuit 1 need to be sampled; therefore, the sampling circuit 6 includes an input voltage sampling unit 61 and a temperature detection unit 63, the input end of the input voltage sampling unit 61 is connected to the power supply end of the power stage circuit 1, the output end of the input voltage sampling unit 61 is connected to the first signal acquisition end of the compensation circuit 5, and the output end of the temperature detection unit 63 is connected to the third signal acquisition end of the compensation circuit 5.

[0071] At the same time, the circuit structure connection mode of the power stage circuit 1 in the second embodiment is also different from that in the first embodiment. The power stage circuit 1 also includes a main switch tube M1, a freewheeling switch tube M2, an inductor L1 and a capacitor C1, wherein the main switch tube M1 and the freewheeling switch tube M2 are both field effect transistors, wherein the source of the main switch tube M1 is connected to the power supply end of the power stage circuit 1, the drain of the main switch tube M1 is respectively connected to the drain of the freewheeling switch tube M2 and one end of the inductor L1, the other end of the inductor L1 is respectively connected to one end of the capacitor C1 and the output end of the power stage circuit 1, the other end of the capacitor C1 is grounded, the gate of the main switch tube M1 and the gate of the freewheeling switch tube M2 are respectively connected to the switching power supply control circuit 4, the drain of the freewheeling switch tube M2 is connected to the second input end of the comparison threshold circuit 2, and the source of the freewheeling switch tube M2 is grounded and also connected to the third input end of the comparison threshold circuit 2.

[0072] At the same time, since the source of the freewheeling switch tube M2 of the step-down DC-DC converter in the second embodiment is connected to the ground, the source and drain voltages of the freewheeling switch tube M2 are close to zero potential, so it is necessary to improve the comparison threshold circuit 2. Fig. 9 The comparison threshold circuit 2 includes a comparison resistor Rcomp and a current source. One end of the comparison resistor Rcomp is connected to the drain of the freewheeling switch tube M2, and the other end is used as the first output end of the comparison threshold circuit 2 and is respectively connected to the output end of the compensation circuit 5, the output end of the current source and the first input end of the zero-crossing detection circuit 3. The second output end of the comparison threshold circuit 2 is connected to the second input end of the zero-crossing detection circuit 3, and the second output end of the comparison threshold circuit 2 is connected to the third input end. The compensation circuit 5 injects current downward to superimpose an offset on the voltage difference signal of the freewheeling switch tube M2, that is, to superimpose the compensation signal and the voltage difference signal and send them to the comparison threshold circuit 2. In this embodiment, the first output end of the comparison threshold circuit 2 outputs the comparison threshold signal, and the second output end of the comparison threshold circuit 2 outputs the reference signal.

[0073] In the second embodiment, the zero-crossing detection circuit 3 also uses a zero-crossing comparator U1 as a threshold comparison processor, the non-inverting input terminal of the zero-crossing comparator U1 is connected to the first input terminal of the comparison threshold circuit 2, the inverting input terminal of the zero-crossing comparator U1 is connected to the second output terminal of the comparison threshold circuit 2, the bias current adjustment input terminal of the zero-crossing comparator U1 is connected to the second output terminal of the compensation circuit 5, the zero-crossing comparator U1 compares the input signals of the non-inverting input terminal and the inverting input terminal and outputs a comparison signal, and feeds the comparison signal back to the switching power supply control circuit 4.

[0074] At the same time, since there is no need to sample the input voltage of the power stage circuit 1, the reference Fig.10 Therefore, the compensation circuit 5 includes a first PMOS type mirror current circuit, a first NMOS type mirror current circuit and a second NMOS type mirror current circuit. The input end of the first PMOS type mirror current circuit is connected to the output end of the first NMOS type mirror current circuit. The output end of the first PMOS type mirror current circuit is simultaneously connected to the first input end of the comparison threshold circuit 2 and the output end of the second NMOS type mirror current circuit. The input end of the first NMOS type mirror current circuit is connected to the output end of the output voltage sampling unit 62 as the first signal acquisition end of the compensation circuit 5. The input end of the second NMOS type mirror current circuit is connected to the output end of the temperature detection unit 63 as the third signal acquisition end of the compensation circuit 5.

[0075] The compensation circuit 5 in the second embodiment has the same structure as that in the first embodiment, and the only difference is that there is no third NMOS type mirror current circuit. Therefore, the output terminal Icomp of the compensation circuit 5 in the second embodiment is Iouts+Iptat, that is, a compensation current, i.e., a compensation signal, which compensates for the real-time output voltage and real-time temperature of the power stage circuit 1 is obtained, so that the output terminal Icomp of the compensation circuit 5 changes with the output voltage and temperature of the power stage circuit 1, and can offset the influence of the temperature and output voltage of the power stage circuit 1 on the zero current detection.

[0076] The switch power supply control circuit 4, the output voltage sampling unit 62 and the temperature detection unit 63 in the second embodiment can adopt the same circuit structure as the first embodiment, and the principle is the same. According to the comparison threshold circuit 2 and the compensation current signal output by the supplementary circuit, an advance threshold, i.e., a compensation signal, is superimposed on the source and drain voltage difference signal of the freewheeling switch tube M2, thereby offsetting the slope of the signal changing with time caused by the output voltage change and the temperature change. At the same time, the compensation signal output by the supplementary circuit 5 is also transmitted to the zero-crossing comparator U1, and the speed of the zero-crossing comparator U1 is changed by changing the bias current of the zero-crossing comparator U1, thereby offsetting the influence of the temperature change on the speed of the comparator. Then, the switch power supply control circuit 4 controls the main switch tube M1 and the freewheeling switch tube M2 in the power stage circuit 1 to be turned on or off according to the output signal of the zero-crossing comparator U1. When the zero-crossing detection comparator U1 detects that the current of the freewheeling switch tube M2 is zero, the freewheeling switch tube M2 is turned off.

[0077] Preferably, in the applied implementation mode, if it is not necessary to sample the temperature change of the power stage circuit 1, that is, the sampling circuit 6 includes an input voltage sampling unit 61 and an output voltage sampling unit 62, the input end of the input voltage sampling unit 61 is connected to the power supply end of the power stage circuit 1, the output end of the input voltage sampling unit 61 is connected to the first signal acquisition end of the compensation circuit 5, the input end of the output voltage sampling unit 62 is connected to the output end of the power stage circuit 1, and the output end of the output voltage sampling unit 62 is connected to the second signal acquisition end of the compensation circuit 5.

[0078] The compensation circuit 5 also has a third embodiment of the structure diagram, refer to Fig.11, the compensation circuit 5 includes a first PMOS type mirror current circuit, a first NMOS type mirror current circuit and a third NMOS type mirror current circuit, the input end of the first PMOS type mirror current circuit is connected to the output end of the first NMOS type mirror current circuit, the output end of the first PMOS type mirror current circuit is simultaneously connected to the first input end of the comparison threshold circuit 2 and the output end of the third NMOS type mirror current circuit, the input end of the first NMOS type mirror current circuit is connected to the output end of the output voltage sampling unit 62, and the input end of the third NMOS type mirror current circuit is connected to the output end of the input voltage sampling unit 61. Its circuit structure is the same as the compensation circuit 5 in the first embodiment, and the only difference is that the structure of the second NMOS mirror current circuit is missing, that is, there is no need to sample the current signal of the temperature change of the power stage circuit 1, then the current Icomp output by the compensation circuit 5 = Iouts + Iins, that is, a compensation current or compensation signal that compensates the real-time input and output voltage of the power stage circuit 1 and the real-time temperature is obtained, so that the output terminal Icomp of the compensation circuit 5 changes with the input and output voltage of the power stage circuit 1, which can offset the influence of the input voltage and output voltage of the power stage circuit 1 on the zero current detection. The circuit structure of other circuits can also be improved according to actual conditions, but the principle is similar to the first embodiment.

[0079] Preferably, if the input voltage of the power stage circuit 1 does not change much, it is not necessary to collect the input voltage signal of the power stage circuit 1, then the sampling circuit 6 includes an output voltage sampling unit 62 and a temperature detection unit 63, the input end of the output voltage sampling unit 62 is connected to the output end of the power stage circuit 1, the output end of the output voltage sampling unit 62 is connected to the second signal collection end of the compensation circuit 5, and the output end of the temperature detection unit 63 is connected to the third signal collection end of the compensation circuit 5. The compensation circuit 5 collects the current signals of the output voltage sampling unit 62 and the temperature detection unit 63 based on the principle of current mirror, and superimposes them, and then outputs the superimposed compensation signal to the comparison threshold circuit 2 and the zero-crossing detection circuit 3.

[0080] Preferably, the power stage circuit 1 changes only when the input voltage changes, and the sampling circuit 6 includes an input voltage sampling unit 61, the input end of the input voltage sampling unit 61 is connected to the power supply end of the power stage circuit 1, and the output end of the input voltage sampling unit 61 is connected to the first signal acquisition end of the compensation circuit 5, and the compensation circuit 5 only needs to collect the signal of the input voltage sampling unit 61.

[0081] Preferably, the power stage circuit 1 changes only when the output voltage changes, and the sampling circuit 6 includes an output voltage sampling unit 62, the input end of the output voltage sampling unit 62 is connected to the output end of the power stage circuit 1, and the output end of the output voltage sampling unit 62 is connected to the second signal acquisition end of the compensation circuit 5, and the compensation circuit 5 only needs to collect the signal of the output voltage sampling unit 62.

[0082] Preferably, the power stage circuit 1 will only change in temperature, then the sampling circuit 6 includes a temperature detection unit 63, the output end of the temperature detection unit 63 is connected to the third signal collection end of the compensation circuit 5, and the compensation circuit 5 only needs to collect the signal of the temperature detection unit 63.

[0083] The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the above embodiments. As long as the technical effects of the present invention are achieved by any same or similar means, they should fall within the protection scope of the present invention.

Claims

1. A zero current detection and regulation system, characterized in that: The invention comprises a power stage circuit (1), a comparison threshold circuit (2), a zero-crossing detection circuit (3) and a switch power supply control circuit (4) which are connected in sequence. The switch power supply control circuit (4) is also connected to the power stage circuit (1). The comparison threshold circuit (2) is also connected to a compensation circuit (5). The compensation circuit (5) is also connected to a sampling circuit. The sampling circuit (6) is used to collect input voltage and / or output voltage and / or temperature signals of the power stage circuit (1). The compensation circuit (5) is also connected to the zero-crossing detection circuit (3) to change the bias current of the zero-crossing detection circuit (3). The comparison threshold circuit (2) collects a voltage difference signal in the power stage circuit (1) and superimposes the voltage difference signal with the compensation signal to form a comparison threshold signal. The comparison threshold circuit (2) simultaneously inputs the comparison threshold signal and the reference signal to the zero-crossing detection circuit (3).

2. The zero current detection and regulation system according to claim 1, characterized in that: The sampling circuit (6) comprises an input voltage sampling unit (61), an output voltage sampling unit (62) and a temperature detection unit (63); the input end of the input voltage sampling unit (61) is connected to the power supply end of the power stage circuit (1); the output end of the input voltage sampling unit (61) is connected to the first signal collection end of the compensation circuit (5); the input end of the output voltage sampling unit (62) is connected to the output end of the power stage circuit (1); the output end of the output voltage sampling unit (62) is connected to the second signal collection end of the compensation circuit (5); and the output end of the temperature detection unit (63) is connected to the third signal collection end of the compensation circuit (5).

3. The zero current detection and regulation system according to claim 1, characterized in that: The sampling circuit (6) comprises an input voltage sampling unit (61) and a temperature detection unit (63); the input end of the input voltage sampling unit (61) is connected to the power supply end of the power stage circuit (1); the output end of the input voltage sampling unit (61) is connected to the first signal collection end of the compensation circuit (5); and the output end of the temperature detection unit (63) is connected to the third signal collection end of the compensation circuit (5).

4. The zero current detection and regulation system according to claim 1, characterized in that: The sampling circuit (6) comprises an output voltage sampling unit (62) and a temperature detection unit (63); the input end of the output voltage sampling unit (62) is connected to the output end of the power stage circuit (1); the output end of the output voltage sampling unit (62) is connected to the second signal collection end of the compensation circuit (5); and the output end of the temperature detection unit (63) is connected to the third signal collection end of the compensation circuit (5).

5. The zero current detection and regulation system according to claim 1, characterized in that: The sampling circuit (6) comprises an input voltage sampling unit (61) and an output voltage sampling unit (62); the input end of the input voltage sampling unit (61) is connected to the power supply end of the power stage circuit (1); the output end of the input voltage sampling unit (61) is connected to the first signal collection end of the compensation circuit (5); the input end of the output voltage sampling unit (62) is connected to the output end of the power stage circuit (1); and the output end of the output voltage sampling unit (62) is connected to the second signal collection end of the compensation circuit (5).

6. A method for zero current detection and regulation, applied to the zero current detection and regulation system according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, the acquisition circuit (6) acquires the input voltage and / or output voltage and / or temperature signals of the power stage circuit (1) in real time and feeds them back to the compensation circuit (5) respectively; S2, the compensation circuit (5) converts at least one signal fed back by the acquisition circuit (6) into a current signal and forms a compensation signal after superposition, and inputs the compensation signal to the comparison threshold circuit (2); the compensation signal of the compensation circuit (5) is input to the zero-crossing detection circuit (3) to adjust the detection speed of the zero-crossing detection circuit (3); S3, the comparison threshold circuit (2) collects the voltage difference signal in the power stage circuit (1) and superimposes it with the compensation signal to form a comparison threshold signal, and the comparison threshold circuit (2) simultaneously inputs the comparison threshold signal and the reference signal to the zero-crossing detection circuit (3); S4, the zero-crossing detection circuit (3) compares the comparison threshold signal output by the comparison threshold circuit (2) with the reference signal and outputs the comparison signal to the switching power supply control circuit; S5. The switch power supply control circuit (4) adjusts the duty cycle of the output signal of the power stage circuit (1) according to the comparison signal.

7. The method for zero current detection and regulation according to claim 6, characterized in that: The voltage difference signal in step S3 is the voltage difference between the source and the drain of the freewheeling switch tube M2 in the power stage circuit (1).

8. The method for zero current detection and regulation according to claim 6, characterized in that: The specific method for adjusting the duty cycle signal of the output signal of the power stage circuit (1) in step S5 is as follows: the switching power supply control circuit (4) controls the on or off time of the main switch tube M1 and the freewheeling switch tube M2 in the power stage circuit (1) according to the comparison signal, so as to adjust the duty cycle of the output signal of the power stage circuit (1).

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