Four-tube buck-boost switching power supply control circuit

Abstract

The invention relates to a four-tube buck-boost switching power supply control circuit, which is characterized in that a switching tube control circuit is designed to collect inductive current and sampling output voltage in a four-tube buck-boost switching power supply circuit, a VCAboost signal and a VCAbuck signal are generated through signal compensation, a duty ratio signal is generated according to a preset sawtooth wave signal VRAMP, and the VCAboost signal and the VCAbuck signal are output. And finally, converting the control signals into control signals corresponding to the four switching tubes respectively, thereby realizing switching of each mode of the four-switching-tube buck-boost power supply circuit. A direct connection stage is added in a buck-boost mode, inductor energy release in mode switching is effectively realized, a large amount of surge current is prevented from passing through the inductor current to cause inductor damage, voltage conversion efficiency and circuit stability are improved, transition between the buck mode and the Boost mode is optimally controlled through the duty ratio, stable change of the duty ratio when a switching tube works is ensured, and the stability of the switching tube is improved. And current fluctuation and loss are avoided.

Description

Technical Field

[0001] The invention relates to a four-tube buck-boost switching power supply control circuit, belonging to the technical field of power electronic converters. Background Art

[0002] In power management systems, switching power supplies are widely used due to their wide voltage range and high efficiency. With the increasing emphasis on low power consumption, switching power supplies are required to operate at lower output voltages and higher output currents. Among them, the four-switch buck-boost (FSBB) circuit, with its wide voltage range and high power output, is primarily used in various consumer electronics and new energy vehicles.

[0003] In traditional three-mode buck-boost converters, switching between buck and boost modes often causes reverse inductor current flow, generating inrush current and reducing system stability and conversion efficiency. Furthermore, traditional designs lack a shoot-through mode, preventing smooth inductor energy transfer during mode switching, resulting in an uneven transition and even compromising system reliability. Furthermore, traditional control methods adjust the duty cycle through frequent switching operations, increasing switching losses and reducing system efficiency.

[0004] The four-switch buck-boost circuit has three operating states. The first stage: Q1 and Q3 are turned on, the energy storage stage, charging the inductor. The second stage: Q2 and Q4 are turned on, the energy transfer stage, transmitting power to the output end by releasing the energy stored in the inductor. The third stage: Q1 and Q4 are turned on, the pass-through stage, achieving direct power transfer from the input to the output end. When the buck-boost circuit switches from buck mode to boost mode, it needs to go through the buck-boost mode. If the traditional buck-boost mode is used, it only includes the energy storage stage and the release stage. At this time, because the energy in the inductor cannot be released in time within one cycle, a large amount of surge current will be generated. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a four-tube buck-boost switching power supply control circuit, which can effectively suppress surge current, optimize the mode switching process, and improve the overall energy transmission efficiency.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: The present invention designs a four-tube buck-boost switching power supply control circuit, including a four-switch-tube buck-boost power supply circuit and a switch tube control circuit. The switch tube control circuit collects the inductor current between the input side half-bridge arm and the output side half-bridge arm of the four-switch-tube buck-boost power supply circuit, and samples the output voltage, generates VCA_boost signal and VCA_buck signal through signal compensation, and then generates VCA_boost signal and VCA_buck signal according to the preset sawtooth wave signal VRAMP The duty cycle signals D1 and D2 are generated and finally converted into control signals corresponding to the four switch tubes in the four-switch tube buck-boost power supply circuit, which are used to control the four-switch tube buck-boost power supply circuit to realize switching between various modes.

[0007] As a preferred technical solution of the present invention: the switch tube control circuit includes a current sampling circuit, a first high-gain high-bandwidth operational amplifier EA1, a second high-gain high-bandwidth operational amplifier EA2, an adding module, a first comparator CMP1, a second comparator CMP2, and a control signal generating circuit; wherein the negative phase input terminal of the first high-gain high-bandwidth operational amplifier EA1 is used to collect the sampled output voltage V of the four-switch tube buck-boost power supply circuit. FB The non-inverting input terminal of the first high-gain high-bandwidth operational amplifier EA1 is used to connect to the preset first reference voltage V REF1 The output end of the first high-gain high-bandwidth operational amplifier EA1 is connected to the non-inverting input end of the second high-gain high-bandwidth operational amplifier EA2, and the first high-gain high-bandwidth operational amplifier EA1 is connected to the non-inverting input end of the second high-gain high-bandwidth operational amplifier EA2 according to the preset first reference voltage V REF1 The sampled output voltage V FB Perform signal compensation to generate the corresponding signal V CP , and output to the second highest gain and high bandwidth operational amplifier EA2;

[0008] The input end of the current sampling circuit is used to collect the inductor current I between the input side half bridge arm and the output side half bridge arm of the four-switch boost power supply circuit. L The output of the current sampling circuit is connected to the negative input of the second high-gain and high-bandwidth operational amplifier EA2. The current sampling circuit measures the inductor current I L Perform scaling and bias processing to obtain the voltage signal V SENSE , and outputs it to the second high-gain high-bandwidth operational amplifier EA2, which is then used to generate the signal V CP For voltage signal V SENSE Perform signal compensation, generate VCA_boost signal and output;

[0009] The output end of the second high-gain, high-bandwidth operational amplifier EA2 is connected to the non-inverting input end of the first comparator CMP1 and one of the input ends of the adding module. The second high-gain, high-bandwidth operational amplifier EA2 outputs the VCA_boost signal to the first comparator CMP1 and the adding module respectively. The other input end of the adding module is used to connect to the preset second reference voltage V REF2 The output end of the adding module is connected to the negative input end of the second comparator CMP2, and the adding module adds the VCA_boost signal and the preset second reference voltage V REF2 Perform superposition to generate a VCA_buck signal and output it to the second comparator CMP2;

[0010] The negative phase input terminal of the first comparator CMP1 and the positive phase input terminal of the second comparator CMP2 are respectively connected to the preset sawtooth wave signal V RAMP The output end of the first comparator CMP1 and the output end of the second comparator CMP2 are connected to the input end of the control signal generating circuit respectively. The first comparator CMP1 performs a control operation on the VCA_boost signal and the preset sawtooth wave signal V RAMP The second comparator CMP2 compares the VCA_buck signal with the preset sawtooth wave signal V RAMP Compare and generate duty cycle signal D2 and output it to control signal generating circuit;

[0011] The control signal generation circuit converts the duty cycle signals D1 and D2 into control signals corresponding to the four switch tubes in the four-switch tube buck-boost power supply circuit, which are used to separately control each switch in the four-switch tube buck-boost power supply circuit to realize the switching of the four-switch tube buck-boost power supply circuit between various modes.

[0012] As a preferred technical solution of the present invention: the switch tube control circuit also includes a dead time and control circuit, each output end of the control signal generation circuit is connected to each input end of the dead time and control circuit, each output end of the dead time and control circuit is respectively connected to the gate of each switch in the four-switch tube buck-boost power supply circuit, the dead time and control circuit includes a delay module and a drive module, each input end of the delay module constitutes each input end of the dead time and control circuit, each output end of the delay module is respectively connected to each input end of the drive module, and each output end of the drive module constitutes each output end of the dead time and control circuit;

[0013] The control signal generation circuit outputs the control signals corresponding to the four switch tubes to the dead time and control circuit. In the dead time and control circuit, the delay module first delays and updates each control signal and outputs it to the drive module, which is used to add dead time between each mode in the working cycle of the four-switch tube buck-boost power supply circuit to prevent the high and low switch tubes from being turned on at the same time; then the drive module converts each control signal into a corresponding drive signal and outputs it to each switch in the four-switch tube buck-boost power supply circuit for driving, thereby realizing the switching of the four-switch tube buck-boost power supply circuit between various modes.

[0014] As a preferred technical solution of the present invention: the current sampling circuit includes a current sampling module, a scaling module, and a bias module connected in series from the input end to the output end, wherein the input end of the current sampling module constitutes the input end of the current sampling circuit, and the output end of the bias module constitutes the output end of the current sampling circuit. The input end of the current sampling circuit collects the inductor current I between the input side half-bridge arm and the output side half-bridge arm of the four-switch tube buck-boost power supply circuit. L , and output to the scaling module, which adjusts the inductor current I L Scaling is performed to obtain the primary voltage signal and output it to the bias module, which then performs bias processing on the primary voltage signal by adding a preset voltage to obtain a voltage signal V SENSE And output.

[0015] As a preferred technical solution of the present invention: the preset sawtooth wave signal V RAMP Generated using a current source capacitor charging and discharging circuit.

[0016] As a preferred technical solution of the present invention: the four-switch tube buck-boost power supply circuit includes a voltage source V1, a capacitor C1, a capacitor C2, a load resistor RL, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, and an inductor L; wherein, the positive electrode of the voltage source V1 is connected to one end of the capacitor C1 and the drain of the switch tube Q1, the other end of the capacitor C1 is connected to one end of its equivalent resistor ESR1, the source of the switch tube Q1 is connected to the drain of the switch tube Q2 and one end of the inductor L, the other end of the inductor L is connected to the source of the switch tube Q4 and the drain of the switch tube Q3, the switch tube Q1 and the switch tube Q2 constitute an input side half-bridge arm, the switch tube Q3 and the switch tube Q4 constitute an output side half-bridge arm, and the current flowing through the inductor L is the inductor current I L The drain of the switch tube Q4 is connected to one end of the capacitor C2 and one end of the load resistor RL. The other end of the capacitor C2 is connected in series with one end of its equivalent resistor ESR2. The negative electrode of the voltage source V1, the other end of the equivalent resistor ESR1, the source of the switch tube Q2, the source of the switch tube Q3, the other end of the equivalent resistor ESR2, and the other end of the load resistor RL are connected and grounded. The two ends of the load resistor constitute the output end of the four-switch tube buck-boost power supply circuit. The sampled output voltage comes from the output end of the four-switch tube buck-boost power supply circuit. The gates of the switch tubes Q1, Q2, Q3, and Q4 respectively constitute the control ends of their respective switches.

[0017] As a preferred technical solution of the present invention: the four-switch tube buck-boost power supply circuit also includes a resistor R1 and a resistor R2, which are connected in series with each other and connected between the positive and negative poles of the output end of the four-switch tube buck-boost power supply circuit. The sampled output voltage is taken from the voltage between the connection point between the resistor R1 and the resistor R2 and the negative pole of the output end of the four-switch tube buck-boost power supply circuit.

[0018] As a preferred technical solution of the present invention: the structures of the switching tubes Q1, Q2, Q3, and Q4 are identical to each other. Each switching tube includes an NMOS tube, a diode, and a capacitor. In the structure of each switching tube, the gate of the NMOS tube constitutes the gate of the switching tube, the drain of the NMOS tube, the negative electrode of the diode, and one end of the capacitor are connected, and the connection position constitutes the drain of the switching tube. The source of the NMOS tube, the positive electrode of the diode, and the other end of the capacitor are connected, and the connection position constitutes the source of the switching tube.

[0019] As a preferred technical solution of the present invention: Regarding the input side voltage V IN , output side voltage V OUT ;

[0020] When V IN >b·V OUT When b>1, the four-switch boost / step-up power supply circuit works in buck mode, and only the VCA_buck signal and the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is the duty cycle signal D2, the driving signal of the switch tube Q2 is the inverse of the duty cycle signal D2, the driving signal of the switch tube Q3 is always 0, and the driving signal of the switch tube Q4 is always 1;

[0021] When V IN <a·V OUT When a<1, the four-switch boost / step-up power supply circuit works in boost mode, and only the VCA_boost signal and the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is always 1, the driving signal of the switch tube Q2 is always 0, the driving signal of the switch tube Q3 is the duty cycle signal D1, and the driving signal of the switch tube Q4 is the inverse of the duty cycle signal D1;

[0022] When a·V OUT <V IN <b·V OUT When the four-switch boost / step-up power supply circuit works in buckboost mode, the VCA_buck signal and the VCA_boost signal are both in phase with the sawtooth wave signal V RAMPThe driving signal of the switch tube Q1 is the duty cycle signal D2, the driving signal of the switch tube Q2 is the inverse of the duty cycle signal D2, the driving signal of the switch tube Q3 is the duty cycle signal D1, and the driving signal of the switch tube Q4 is the inverse of the duty cycle signal D1.

[0023] The four-tube buck-boost switching power supply control circuit of the present invention, which adopts the above technical solution, has the following technical effects compared with the prior art:

[0024] (1) The present invention designs a four-tube buck-boost switching power supply control circuit, designs a switch tube control circuit to collect the inductor current and sample the output voltage in the four-tube buck-boost power supply circuit, generates VCA_boost signal and VCA_buck signal through signal compensation, and then generates VCA_boost signal according to the preset sawtooth wave signal V RAMP A duty cycle signal is generated and finally converted into control signals corresponding to the four switching tubes, realizing the switching of various modes of the four-switch buck-boost power supply circuit; a pass-through stage is added to the buck-boost mode to effectively realize the release of inductor energy during mode switching, reduce the average value of the inductor current and the inductor loss, prevent a large amount of surge current from passing through the inductor current and causing inductor damage, improve voltage conversion efficiency and circuit stability, and can withstand working conditions under high current output; and through duty cycle optimization, the transition between Buck mode and Boost mode is controlled to ensure smooth changes in the duty cycle when the switching tube is working, avoiding current fluctuations and losses. The solution can cope with different load conditions and a wide range of input voltage fluctuations, and is suitable for high-efficiency power management systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a four-tube buck-boost switching power supply control circuit designed by the present invention;

[0026] Figure 2 Schematic diagram of voltage and current waveforms and control signals in various modes under the design and application of the present invention;

[0027] Figure 3 This is a comparison chart of the mode efficiency simulation between the three modes designed and applied by the present invention and the traditional three modes;

[0028] Figure 4 This is a comparison chart of transient simulation of mode inductor currents between the three modes designed and applied by the present invention and the traditional three modes;

[0029] Figure 5 This is a comparison diagram of the inductor current ripple cadence simulation after the circuit loop buckboost mode is stabilized under the design and application of the present invention. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] The present invention designs a four-tube buck-boost switching power supply control circuit, which includes a four-switch-tube buck-boost power supply circuit and a switch tube control circuit, wherein Figure 1 As shown, the four-switch boost / buck power supply circuit includes a voltage source V1, a capacitor C1, a capacitor C2, a load resistor RL, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, an inductor L, a resistor R1, and a resistor R2; wherein, the positive electrode of the voltage source V1 is connected to one end of the capacitor C1 and the drain of the switch tube Q1, the other end of the capacitor C1 is connected to one end of its equivalent resistor ESR1, the source of the switch tube Q1 is connected to the drain of the switch tube Q2 and one end of the inductor L, the other end of the inductor L is connected to the source of the switch tube Q4 and the drain of the switch tube Q3, the switch tube Q1 and the switch tube Q2 form an input side half-bridge arm, the switch tube Q3 and the switch tube Q4 form an output side half-bridge arm, and the switch tube Q4 The drain of the capacitor C2 is connected to one end of the capacitor C2 and one end of the load resistor RL. The other end of the capacitor C2 is connected in series with one end of its equivalent resistor ESR2. The negative electrode of the voltage source V1, the other end of the equivalent resistor ESR1, the source of the switch tube Q2, the source of the switch tube Q3, the other end of the equivalent resistor ESR2, and the other end of the load resistor RL are connected and grounded. The two ends of the load resistor constitute the output end of the four-switch tube buck-boost power supply circuit. The resistors R1 and R2 are connected in series and then connected between the positive and negative electrodes of the output end of the four-switch tube buck-boost power supply circuit. The gates of the switch tubes Q1, Q2, Q3, and Q4 respectively constitute the control ends of their switches.

[0032] In actual applications, the structures of the four switching tubes Q1, Q2, Q3, and Q4 are the same. Each switching tube includes an NMOS tube, a diode, and a capacitor. In the structure of each switching tube, the gate of the NMOS tube constitutes the gate of the switching tube, the drain of the NMOS tube, the negative electrode of the diode, and one end of the capacitor are connected, and the connection position constitutes the drain of the switching tube. The source of the NMOS tube, the positive electrode of the diode, and the other end of the capacitor are connected, and the connection position constitutes the source of the switching tube.

[0033] For the above four-switch boost / step-up power supply circuit, a switch control circuit is designed to collect the inductor current I flowing through the inductor L in the four-switch boost / step-up power supply circuit. L , and the sampling output voltage V between the connection position between the acquisition resistor R1 and the resistor R2 and the negative electrode of the output terminal of the four-switch boost / step-up power supply circuit FB , generate VCA_boost signal and VCA_buck signal through signal compensation, and then according to the preset sawtooth wave signal V RAMPThe duty cycle signals D1 and D2 are generated and finally converted into control signals corresponding to the four switch tubes in the four-switch tube buck-boost power supply circuit, which are used to control the four-switch tube buck-boost power supply circuit to realize switching between various modes.

[0034] In practical applications, such as Figure 1 As shown, the specific design of the switch tube control circuit includes a current sampling circuit, a first high-gain high-bandwidth operational amplifier EA1, a second high-gain high-bandwidth operational amplifier EA2, an adding module, a first comparator CMP1, a second comparator CMP2, a control signal generating circuit, a dead time and control circuit; wherein, the negative input terminal of the first high-gain high-bandwidth operational amplifier EA1 is used to collect the access sample output voltage V FB ,Right now The positive input terminal of the first high-gain high-bandwidth operational amplifier EA1 is used to connect to the preset first reference voltage V REF1 =1.22V, the output end of the first high-gain high-bandwidth operational amplifier EA1 is connected to the non-inverting input end of the second high-gain high-bandwidth operational amplifier EA2, and the first high-gain high-bandwidth operational amplifier EA1 is connected to the positive input end of the second high-gain high-bandwidth operational amplifier EA2 according to the preset first reference voltage V REF1 The sampled output voltage V FB Perform type 2 signal compensation to generate the corresponding signal V CP , and output to the second high gain high bandwidth operational amplifier EA2, which will sample the output voltage V FB Locked to near the preset first reference voltage.

[0035] The input end of the current sampling circuit is used to collect the inductor current I L The output of the current sampling circuit is connected to the negative input of the second high-gain and high-bandwidth operational amplifier EA2. The current sampling circuit measures the inductor current I L Perform scaling and bias processing to obtain the voltage signal V SENSE , and outputs it to the second high-gain high-bandwidth operational amplifier EA2, which is then used to generate the signal V CP For voltage signal V SENSE Perform type 2 signal compensation, generate a VCA_boost signal, and output it.

[0036] In practical applications, the current sampling circuit is specifically designed to include a current sampling module, a scaling module, and a bias module connected in series from the input end to the output end. The input end of the current sampling module constitutes the input end of the current sampling circuit, and the output end of the bias module constitutes the output end of the current sampling circuit. The input end of the current sampling circuit collects the inductor current I between the input side half-bridge arm and the output side half-bridge arm in the four-switch boost / boost power supply circuit. L , and output to the scaling module, which uses a preset ratio such as 0.04 times to adjust the inductor current IL Scaling is performed to obtain the primary voltage signal and output it to the bias module, which then adds a preset 2V DC bias voltage to the primary voltage signal for bias processing. SENSE =0.04*I L +2, get the voltage signal V SENSE And output.

[0037] like Figure 1 As shown, the output end of the second high-gain high-bandwidth operational amplifier EA2 is connected to the non-inverting input end of the first comparator CMP1 and one of the input ends of the adding module respectively. The second high-gain high-bandwidth operational amplifier EA2 outputs the VCA_boost signal to the first comparator CMP1 and the adding module respectively. The other input end of the adding module is used to connect to the preset second reference voltage V REF2 The output end of the adding module is connected to the negative input end of the second comparator CMP2, and the adding module adds the VCA_boost signal and the preset second reference voltage V REF2 =1V to generate a VCA_buck signal and output it to the second comparator CMP2.

[0038] like Figure 1 As shown, the negative phase input terminal of the first comparator CMP1 and the positive phase input terminal of the second comparator CMP2 are respectively connected to the preset sawtooth wave signal V RAMP The output end of the first comparator CMP1 and the output end of the second comparator CMP2 are connected to the input end of the control signal generating circuit respectively. The first comparator CMP1 performs a control operation on the VCA_boost signal and the preset sawtooth wave signal V RAMP The second comparator CMP2 compares the VCA_buck signal with the preset sawtooth wave signal V RAMP The comparison is performed to generate a duty cycle signal D2 and output it to the control signal generation circuit.

[0039] Here the sawtooth wave signal V is preset RAMP The current source capacitor charging and discharging circuit is used to generate a sawtooth wave signal V with a voltage of 2.3 to 3.6 V and a frequency of 600 KHz. RAMP .

[0040] like Figure 1As shown, the output terminals of the control signal generation circuit are connected to the input terminals of the dead time and control circuit, and the output terminals of the dead time and control circuit are respectively connected to the gate terminals of each switch in the four-switch buck-boost power supply circuit. The dead time and control circuit includes a delay module and a driver module. The input terminals of the delay module constitute the input terminals of the dead time and control circuit, and the output terminals of the delay module are respectively connected to the input terminals of the driver module, and the output terminals of the driver module constitute the output terminals of the dead time and control circuit. The control signal generation circuit outputs the control signals corresponding to the four switches to the dead time and control circuit. The delay module in the dead time and control circuit first delays and updates each control signal and outputs it to the driver module. This is used to add dead time between the various modes in the operating cycle of the four-switch buck-boost power supply circuit to prevent the high and low switches from being turned on at the same time. The driver module then converts each control signal into a corresponding drive signal and outputs it to each switch in the four-switch buck-boost power supply circuit, driving the switch to turn on or off, thereby switching the four-switch buck-boost power supply circuit between various modes.

[0041] In the actual implementation of the above design scheme, Figure 2 As shown, based on the VCA_boost signal and the sawtooth wave signal V RAMP Compare and generate duty cycle signal D1, and VCA_buck signal and sawtooth wave signal V RAMP By comparison, a duty cycle signal D2 is generated, and the switching strategies of the four-switch buck-boost power supply circuit for each mode are as follows.

[0042] When V IN >b·V OUT When b>1, the four-switch boost / step-up power supply circuit works in buck mode, and only the VCA_buck signal and the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is the duty cycle signal D2, the driving signal of the switch tube Q2 is the inverse of the duty cycle signal D2, the driving signal of the switch tube Q3 is always 0, and the driving signal of the switch tube Q4 is always 1;

[0043] When V IN <a·V OUT When a<1, the four-switch boost / step-up power supply circuit works in boost mode, and only the VCA_boost signal and the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is always 1, the driving signal of the switch tube Q2 is always 0, the driving signal of the switch tube Q3 is the duty cycle signal D1, and the driving signal of the switch tube Q4 is the inverse of the duty cycle signal D1;

[0044] When a·V OUT <V IN <b·V OUTWhen the four-switch boost / step-up power supply circuit works in buckboost mode, the VCA_buck signal and the VCA_boost signal are both in phase with the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is the duty cycle signal D2, the driving signal of the switch tube Q2 is the inverse of the duty cycle signal D2, the driving signal of the switch tube Q3 is the duty cycle signal D1, and the driving signal of the switch tube Q4 is the inverse of the duty cycle signal D1.

[0045] The four-tube buck-boost switching power supply control circuit designed by the present invention is used in practical applications, such as Figure 3 As shown, under the conditions of an input voltage of 36V, an output voltage of 36V, a load of 0.2-5A, and a switching frequency of 600kHz, the cadence simulation efficiency comparison results of the three-mode of the present invention using a 0.18um process are compared with those of a traditional three-mode. The efficiency is defined as the product of the average output voltage and the average output current over the simulated 30-35ms divided by the product of the average input voltage and the average input current over the 30-35ms. The traditional three-mode, in buckboost operation, contains only storage and release phases. The theoretical peak efficiency under this mode is 95.77%. The theoretical peak efficiency of the three-mode using the design of the present invention is 98.18%.

[0046] like Figure 4 As shown in FIG. 1 , under the conditions of an input voltage of 36V, an output voltage of 36V, a load of 3A, and a switching frequency of 600kHz, the comparison results of the inductor currents of the three-mode cadence simulation of the present invention and the traditional three-mode under the 0.18um process are shown. The peak surge current of the traditional mode is 35.4A, while the peak surge current of the three-mode under the design and application of the present invention is 8.3A.

[0047] like Figure 5 As shown, the upper figure is a comparison of the peak inrush current during transient startup, and the lower figure is a comparison of the current ripple of the inductor current small signal. Under the conditions of an input voltage of 36V, an output voltage of 36V, a load of 3A, and a switching frequency of 600kHz, the three-mode cadence simulation inductor current of the present invention under a 0.18um process is compared with the traditional three-mode cadence simulation inductor current. The traditional mode inductor current has a ripple of 13.76A and an average inductor current of 6.356A. Under the design and application of the present invention, the three-mode inductor current ripple is 13.76A and the average inductor current is 3.399A. The lower inductor current can reduce inductor loss and improve conversion efficiency under buckboost conditions.

[0048] The present invention designs a four-tube buck-boost switching power supply control circuit, designs a switch tube control circuit to collect the inductor current and sample the output voltage in the four-switch tube buck-boost power supply circuit, generates VCA_boost signal and VCA_buck signal through signal compensation, and then generates VCA_boost signal according to the preset sawtooth wave signal VRAMP A duty cycle signal is generated and finally converted into control signals corresponding to the four switching tubes, realizing the switching of various modes of the four-switch buck-boost power supply circuit; a pass-through stage is added to the buck-boost mode to effectively realize the release of inductor energy during mode switching, reduce the average value of the inductor current and the inductor loss, prevent a large amount of surge current from passing through the inductor current and causing inductor damage, improve voltage conversion efficiency and circuit stability, and can withstand working conditions under high current output; and through duty cycle optimization, the transition between Buck mode and Boost mode is controlled to ensure smooth changes in the duty cycle when the switching tube is working, avoiding current fluctuations and losses. The solution can cope with different load conditions and a wide range of input voltage fluctuations, and is suitable for high-efficiency power management systems.

[0049] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the spirit of the present invention.

Claims

1. A four-tube buck-boost switching power supply control circuit, characterized in that: The system includes a four-switch boost / buck power supply circuit and a switch control circuit. The switch control circuit collects the inductor current between the input side half-bridge arm and the output side half-bridge arm of the four-switch boost / buck power supply circuit, and samples the output voltage. It generates VCA_boost and VCA_buck signals through signal compensation, and then generates VCA_boost and VCA_buck signals according to the preset sawtooth wave signal V RAMP The duty cycle signals D1 and D2 are generated and finally converted into control signals corresponding to the four switch tubes in the four-switch tube buck-boost power supply circuit, which are used to control the four-switch tube buck-boost power supply circuit to realize switching between various modes.

2. The four-tube buck-boost switching power supply control circuit according to claim 1, characterized in that: The switch tube control circuit includes a current sampling circuit, a first high-gain high-bandwidth operational amplifier EA1, a second high-gain high-bandwidth operational amplifier EA2, an adding module, a first comparator CMP1, a second comparator CMP2, and a control signal generating circuit; wherein the negative phase input terminal of the first high-gain high-bandwidth operational amplifier EA1 is used to collect the sampled output voltage V of the four-switch tube buck-boost power supply circuit. FB The non-inverting input terminal of the first high-gain high-bandwidth operational amplifier EA1 is used to connect to the preset first reference voltage V REF1 The output end of the first high-gain high-bandwidth operational amplifier EA1 is connected to the non-inverting input end of the second high-gain high-bandwidth operational amplifier EA2, and the first high-gain high-bandwidth operational amplifier EA1 is connected to the non-inverting input end of the second high-gain high-bandwidth operational amplifier EA2 according to the preset first reference voltage V REF1 The sampled output voltage V FB Perform signal compensation to generate the corresponding signal V CP , and output to the second highest gain and high bandwidth operational amplifier EA2; The input end of the current sampling circuit is used to collect the inductor current I between the input side half bridge arm and the output side half bridge arm of the four-switch boost / boost power supply circuit. L The output of the current sampling circuit is connected to the negative input of the second high-gain and high-bandwidth operational amplifier EA2. The current sampling circuit measures the inductor current I L Perform scaling and bias processing to obtain the voltage signal V SENSE , and outputs it to the second high-gain high-bandwidth operational amplifier EA2, which is then used to generate the signal V CP For voltage signal V SENSE Perform signal compensation, generate VCA_boost signal and output; The output end of the second high-gain, high-bandwidth operational amplifier EA2 is connected to the non-inverting input end of the first comparator CMP1 and one of the input ends of the adding module. The second high-gain, high-bandwidth operational amplifier EA2 outputs the VCA_boost signal to the first comparator CMP1 and the adding module respectively. The other input end of the adding module is used to connect to the preset second reference voltage V REF2 The output end of the adding module is connected to the negative input end of the second comparator CMP2, and the adding module adds the VCA_boost signal and the preset second reference voltage V REF2 Perform superposition to generate a VCA_buck signal and output it to the second comparator CMP2; The negative phase input terminal of the first comparator CMP1 and the positive phase input terminal of the second comparator CMP2 are respectively connected to the preset sawtooth wave signal V RAMP The output end of the first comparator CMP1 and the output end of the second comparator CMP2 are connected to the input end of the control signal generating circuit respectively. The first comparator CMP1 performs a control operation on the VCA_boost signal and the preset sawtooth wave signal V RAMP The second comparator CMP2 compares the VCA_buck signal with the preset sawtooth wave signal V RAMP Compare and generate duty cycle signal D2 and output it to control signal generating circuit; The control signal generation circuit converts the duty cycle signals D1 and D2 into control signals corresponding to the four switch tubes in the four-switch tube buck-boost power supply circuit, which are used to separately control each switch in the four-switch tube buck-boost power supply circuit to realize the switching of the four-switch tube buck-boost power supply circuit between various modes.

3. The four-tube buck-boost switching power supply control circuit according to claim 2, characterized in that: The switch tube control circuit also includes a dead time and control circuit. The output terminals of the control signal generation circuit are connected to the input terminals of the dead time and control circuit. The output terminals of the dead time and control circuit are respectively connected to the gates of the switches in the four-switch tube buck-boost power supply circuit. The dead time and control circuit includes a delay module and a drive module. The input terminals of the delay module constitute the input terminals of the dead time and control circuit. The output terminals of the delay module are respectively connected to the input terminals of the drive module. The output terminals of the drive module constitute the output terminals of the dead time and control circuit. The control signal generation circuit outputs the control signals corresponding to the four switch tubes to the dead time and control circuit. In the dead time and control circuit, the delay module first delays and updates each control signal and outputs it to the drive module, which is used to add dead time between each mode in the working cycle of the four-switch tube buck-boost power supply circuit to prevent the high and low switch tubes from being turned on at the same time; then the drive module converts each control signal into a corresponding drive signal and outputs it to each switch in the four-switch tube buck-boost power supply circuit for driving, thereby realizing the switching of the four-switch tube buck-boost power supply circuit between various modes.

4. The four-tube buck-boost switching power supply control circuit according to claim 2, characterized in that: The current sampling circuit includes a current sampling module, a scaling module, and a bias module connected in series from the input end to the output end. The input end of the current sampling module constitutes the input end of the current sampling circuit, and the output end of the bias module constitutes the output end of the current sampling circuit. The input end of the current sampling circuit collects the inductor current I between the input side half-bridge arm and the output side half-bridge arm in the four-switch boost / boost power supply circuit. L , and output to the scaling module, which adjusts the inductor current I L Scaling is performed to obtain the primary voltage signal and output it to the bias module, which then performs bias processing on the primary voltage signal by adding a preset voltage to obtain a voltage signal V SENSE And output.

5. A four-tube buck-boost switching power supply control circuit according to claim 1 or 2, characterized in that: The preset sawtooth wave signal V RAMP Generated using a current source capacitor charging and discharging circuit.

6. A four-tube buck-boost switching power supply control circuit according to any one of claims 1 to 5, characterized in that: The four-switch tube buck-boost power supply circuit includes a voltage source V1, a capacitor C1, a capacitor C2, a load resistor RL, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, and an inductor L; wherein, the positive electrode of the voltage source V1 is connected to one end of the capacitor C1 and the drain of the switch tube Q1, the other end of the capacitor C1 is connected to one end of its equivalent resistor ESR1, the source of the switch tube Q1 is connected to the drain of the switch tube Q2 and one end of the inductor L, the other end of the inductor L is connected to the source of the switch tube Q4 and the drain of the switch tube Q3, the switch tube Q1 and the switch tube Q2 form an input side half-bridge arm, the switch tube Q3 and the switch tube Q4 form an output side half-bridge arm, and the current flowing through the inductor L is the inductor current I L The drain of the switch tube Q4 is connected to one end of the capacitor C2 and one end of the load resistor RL. The other end of the capacitor C2 is connected in series with one end of its equivalent resistor ESR2. The negative electrode of the voltage source V1, the other end of the equivalent resistor ESR1, the source of the switch tube Q2, the source of the switch tube Q3, the other end of the equivalent resistor ESR2, and the other end of the load resistor RL are connected and grounded. The two ends of the load resistor constitute the output end of the four-switch tube buck-boost power supply circuit. The sampled output voltage comes from the output end of the four-switch tube buck-boost power supply circuit. The gates of the switch tubes Q1, Q2, Q3, and Q4 respectively constitute the control ends of their respective switches.

7. The four-tube buck-boost switching power supply control circuit according to claim 6, characterized in that: The four-switch tube buck-boost power supply circuit also includes a resistor R1 and a resistor R2. The resistors R1 and R2 are connected in series and connected between the positive and negative electrodes of the output end of the four-switch tube buck-boost power supply circuit. The sampled output voltage is obtained from the voltage between the connection point between the resistors R1 and R2 and the negative electrode of the output end of the four-switch tube buck-boost power supply circuit.

8. The four-tube buck-boost switching power supply control circuit according to claim 7, characterized in that: The switching tubes Q1, Q2, Q3, and Q4 have the same structure. Each switching tube includes an NMOS tube, a diode, and a capacitor. In the structure of each switching tube, the gate of the NMOS tube constitutes the gate of the switching tube, the drain of the NMOS tube, the negative electrode of the diode, and one end of the capacitor are connected, and the connection position constitutes the drain of the switching tube. The source of the NMOS tube, the positive electrode of the diode, and the other end of the capacitor are connected, and the connection position constitutes the source of the switching tube.

9. The four-tube buck-boost switching power supply control circuit according to claim 7, characterized in that: Regarding the input side voltage V of the four-switch boost / step-up power supply circuit IN , output side voltage V OUT ; When V IN >b·V OUT When b>1, the four-switch boost / step-up power supply circuit works in buck mode, and only the VCA_buck signal and the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is the duty cycle signal D2, the driving signal of the switch tube Q2 is the inverse of the duty cycle signal D2, the driving signal of the switch tube Q3 is always 0, and the driving signal of the switch tube Q4 is always 1; When V IN <a·V OUT When a<1, the four-switch boost / step-up power supply circuit works in boost mode, and only the VCA_boost signal and the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is always 1, the driving signal of the switch tube Q2 is always 0, the driving signal of the switch tube Q3 is the duty cycle signal D1, and the driving signal of the switch tube Q4 is the inverse of the duty cycle signal D1; When a·V OUT <V IN <b·V OUT When the four-switch boost / step-up power supply circuit works in buckboost mode, the VCA_buck signal and the VCA_boost signal are both in phase with the sawtooth wave signal V RAMP The driving signal of the switch tube Q1 is the duty cycle signal D2, the driving signal of the switch tube Q2 is the inverse of the duty cycle signal D2, the driving signal of the switch tube Q3 is the duty cycle signal D1, and the driving signal of the switch tube Q4 is the inverse of the duty cycle signal D1.

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