Converter control circuit and converter

Abstract

The invention discloses a converter control circuit and a converter, and the control circuit comprises a compensation signal generation unit which is configured to generate a compensation signal based on the output voltage of the converter; the ripple signal generation unit is configured to generate a ripple signal based on a control signal of the power switch tube and a first reference voltage signal; the comparison unit is configured to compare a first comparison signal and a second comparison signal to obtain a comparison result, the first comparison signal is obtained by superposing a feedback signal and a ripple signal of the converter, and the second comparison signal is obtained by superposing a compensation signal and a second reference voltage signal; the feedback signal represents an output voltage feedback signal or an inductive current feedback signal; and the control unit is configured to control the power switch tube and the follow current switch tube based on the comparison result. According to the converter control circuit, respective transmission among a plurality of signals is realized, so that the flexibility of the converter control circuit is improved, and the circuit application range of the converter is greatly expanded.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a control circuit and converter for a converter. Background Technology

[0002] In power-related applications, converters are generally used to convert input voltage into desired output voltage. They typically consist of switching transistors and inductors, and adjust the on and off states of the switching transistors in response to fluctuations in the output voltage to maintain the stability of the output voltage.

[0003] In related technologies, the control process of converters often has certain limitations. For example, the output voltage feedback signal and reference signal of the converter are typically amplified to obtain an error signal. This error signal is then superimposed with the correlation signal of the inductor current to obtain a compensation signal. Finally, the switching transistor is controlled based on the comparison result between the compensation signal and the output voltage feedback signal. However, the high degree of signal coupling between the error signal and the correlation signal of the inductor current reduces the flexibility of the converter control method and limits the applicability of the converter. Summary of the Invention

[0004] This application provides a control circuit and converter for a converter, which solves the technical problem that the current control method of converter has a high degree of signal coupling, resulting in low flexibility of the converter control method. By decoupling and superimposing different signals respectively, a fast response to output voltage fluctuations is achieved, and the flexibility of the converter control method is improved, thereby expanding the circuit application range of the converter.

[0005] To achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In a first aspect, embodiments of this application provide a control circuit for a converter, the converter including an inductor, a power switch, and a freewheeling switch. The control circuit includes: a compensation signal generation unit configured to generate a compensation signal based on the output voltage of the converter; a ripple signal generation unit configured to generate a ripple signal based on a control signal of the power switch and a first reference voltage signal, wherein the ripple signal is in phase with the inductor current; a comparison unit configured to compare a first comparison signal and a second comparison signal to obtain a comparison result, wherein the first comparison signal is obtained by superimposing a feedback signal of the converter with the ripple signal, and the second comparison signal is obtained by superimposing the compensation signal with the second reference voltage signal, the feedback signal representing an output voltage feedback signal or an inductor current feedback signal; and a control unit configured to control the power switch and the freewheeling switch based on the comparison result.

[0007] The control circuit proposed in this application receives the converter's feedback signal, compensation signal, and ripple signal through a comparison unit, and outputs a comparison result based on these signals to control the power switch and freewheeling switch. Therefore, this application's embodiment receives the converter's feedback signal, compensation signal, and ripple signal through a comparison unit, enabling separate transmission of multiple signals. Furthermore, the generation units for the feedback signal, compensation signal, and ripple signal are independent, allowing for independent adjustment of the compensation signal by the compensation resistor, increasing the converter's system dynamic adjustment and improving stability. Secondly, by superimposing the converter's feedback signal and ripple signal to obtain the first comparison signal, and by superimposing the compensation signal and the second reference voltage signal to obtain the second comparison signal, the phase difference between the switch's control signal and the inductor current can be improved, enhancing system stability. Moreover, the technical solution proposed in this application has a wide applicability due to the independent acquisition of the ripple signal and compensation signal, and the overall system stability is good with a faster response speed.

[0008] Optionally, in some embodiments of this application, the second reference voltage signal is set according to the magnitude of the first reference voltage signal.

[0009] In this embodiment, a corresponding second reference voltage signal is set according to the first reference voltage signal, thereby eliminating the influence of the first reference voltage on the ripple signal and improving the system stability of the converter.

[0010] Optionally, in some embodiments of this application, the ripple signal is directly proportional to the inductor current.

[0011] Optionally, in some embodiments of this application, the comparison unit includes a comparator, which includes a first positive input terminal, a second positive input terminal, a first negative input terminal, and a second negative input terminal. The first positive input terminal is adapted to receive the compensation signal, the second positive input terminal is adapted to receive the second reference voltage signal, the first negative input terminal is adapted to receive the feedback signal of the converter, and the second negative input terminal is adapted to receive the ripple signal.

[0012] The comparator proposed in this application receives the compensation signal, the second reference voltage signal, the feedback signal, and the ripple signal through multiple different input terminals to achieve decoupling between the compensation signal and the ripple signal. This makes the generation units of the feedback signal, the compensation signal, and the ripple signal independent of each other, which not only improves the flexibility of the converter control circuit, but also reduces the interference between the output signal, the compensation signal, and the ripple signal.

[0013] Optionally, in some embodiments of this application, the first negative input terminal is adapted to receive a feedback voltage signal for characterizing the output voltage feedback signal of the converter.

[0014] This application embodiment receives a feedback voltage signal that characterizes the output voltage feedback signal of the converter, so as to perform precise voltage-type control of the converter based on the voltage change at the output terminal. This enables the control circuit to be adapted to the converter that operates in voltage-type control mode, thereby simplifying the control circuit structure of the converter and improving the response speed of the converter.

[0015] Optionally, in some embodiments of this application, the first negative input terminal is adapted to receive a current sampling signal for characterizing the inductor current feedback signal of the converter.

[0016] This application embodiment receives a current sampling signal used to characterize the inductor current feedback signal of the converter, and performs precise current-type control of the converter based on the current at the output terminal. This enables the control circuit to be applicable to converters operating in current-type control mode, thereby effectively limiting the inductor current and improving the reliability of the converter.

[0017] Optionally, in some embodiments of this application, the control circuit further includes a current sampling unit configured to sample the inductor current of the converter to obtain the current sampling signal.

[0018] Optionally, in some embodiments of this application, the current sampling unit includes:

[0019] A current sampling resistor is connected between the inductor and the output terminal of the converter;

[0020] A low-pass filter, wherein the first input terminal of the low-pass filter is connected to the first terminal of the current sampling resistor, and the second input terminal of the low-pass filter is connected to the second terminal of the current sampling resistor;

[0021] An operational amplifier is provided, wherein the positive input terminal of the operational amplifier is connected to the first output terminal of the low-pass filter, the negative input terminal of the operational amplifier is connected to the second output terminal of the low-pass filter, and the output terminal of the operational amplifier is connected to the first negative input terminal of the comparator, so as to send the current sampling signal into the comparator.

[0022] This embodiment addresses the problem of weak sampling current and susceptibility to external switching noise in high-current converters by employing a current sampling unit. A low-pass filter is used to filter the current sampling signal passing through the current sampling resistor, and an operational amplifier amplifies the filtered signal to improve the sampling effect of the output signal. Furthermore, the limited bandwidth of the operational amplifier also contributes to the low-pass filtering effect. Therefore, using an operational amplifier not only improves the weak sampling signal and susceptibility to external switching noise in high-current converters but also significantly enhances the noise immunity of the current sampling unit, thereby facilitating a faster and more accurate response to output voltage fluctuations.

[0023] Optionally, in some embodiments of this application, the control unit includes an RS flip-flop, one of the set terminal and the reset terminal of the RS flip-flop is connected to the output terminal of the comparator unit, the first output terminal of the RS flip-flop is connected to the gate of the power switch, and the second output terminal of the RS flip-flop is connected to the gate of the freewheeling switch.

[0024] In this embodiment, an RS flip-flop generates a stable control signal based on the output signal of the comparator unit to ensure that the power switch and freewheeling switch are turned on or off at the appropriate time, thereby achieving efficient and accurate voltage regulation control.

[0025] Optionally, in some embodiments of this application, when the converter operates in voltage-mode or current-mode control, the set terminal of the RS flip-flop is connected to the output terminal of the comparator unit.

[0026] In this embodiment, the output of the comparator is connected to the set terminal of the RS flip-flop to enable rapid and accurate control of the power switch and the freewheeling switch based on the voltage or current changes at the converter output in either voltage-mode or current-mode control, thereby effectively maintaining the stability of the converter's output voltage.

[0027] Optionally, in some embodiments of this application, when the converter operates in a fixed-frequency peak current control mode, the reset terminal of the RS flip-flop is connected to the output terminal of the comparator unit.

[0028] In this embodiment, the output of the comparator is connected to the reset terminal of the RS flip-flop. This enables the power switch to be turned off and the freewheeling switch to be turned on quickly and accurately when the current at the converter output reaches its peak value in the fixed-frequency peak current control mode, thereby effectively maintaining the stability of the converter's output voltage.

[0029] Optionally, in some embodiments of this application, when the converter operates in voltage-mode or current-mode control, the ripple signal generation unit includes:

[0030] A first current source, the output current of which is determined based on the input voltage of the converter;

[0031] A first switch, the first end of which is connected to the positive terminal of the first current source, and the first switch is turned off or closed based on the control signal of the power switch tube;

[0032] A first resistor, the first end of which is connected to the second end of the first switch, and the second end of the first resistor is grounded;

[0033] A second resistor, the first end of which is adapted to be connected to a first reference voltage signal;

[0034] A first capacitor, wherein a first terminal of the first capacitor is connected to a second terminal of the first switch, a second terminal of the first capacitor is connected to a second terminal of the second resistor, and has a first node;

[0035] Two capacitors, with the first terminal of the second capacitor grounded and the second terminal of the second capacitor connected to the first node, the first node being used to provide the ripple signal.

[0036] This application uses a charging and discharging circuit composed of a first current source, a first switch, a first resistor, and a second resistor. The charging and discharging circuit is controlled to charge and discharge the first capacitor and the second capacitor according to the control signal of the power switch and the first reference voltage signal. This generates a ripple signal that is in phase with the inductor current at the first node. Therefore, the delay of the inductor current signal can be compensated by the ripple signal, and the phase difference between the control signal and the inductor current can be improved, thereby greatly improving the stability of the converter.

[0037] Optionally, in some embodiments of this application, when the converter needs to operate in a fixed-frequency peak current control mode, the ripple signal generation unit further includes:

[0038] The second current source, the output current of which is determined according to the output voltage of the converter;

[0039] The second switch has its first end connected to the positive terminal of the second current source, and the second switch is turned off or closed based on the control signal of the power switch tube.

[0040] The third capacitor has its first end connected to the second end of the second switch, and the second end of the second capacitor is connected to the first node.

[0041] This application uses a charging and discharging circuit composed of a second current source and a second switch to charge and discharge a third capacitor according to the control signal of the power switch tube, so as to generate a sawtooth wave to solve the harmonic oscillation problem that may be generated in the fixed frequency peak current type control mode, thereby effectively improving the noise immunity of the converter and further improving the stability of the converter.

[0042] Optionally, in some embodiments of this application, the compensation signal generation unit includes:

[0043] The third resistor, the first end of which is connected to the output terminal of the converter;

[0044] A fourth resistor, wherein the first end of the fourth resistor is connected to the second end of the third resistor and has a second node, and the second end of the fourth resistor is grounded;

[0045] An error amplifier is provided, wherein the positive input terminal of the error amplifier is adapted to receive a third reference voltage signal, the negative input terminal of the error amplifier is connected to the second node, and the output terminal of the error amplifier is used to output the compensation signal.

[0046] A compensation capacitor, the first end of which is connected to the output terminal of the error amplifier;

[0047] A compensation resistor, the first end of which is connected to the second end of the compensation capacitor, and the second end of the compensation resistor is grounded.

[0048] This application enables effective compensation of the converter output voltage through a compensation signal generation unit, which helps improve the converter's stability and anti-interference capability, and ensures reliable operation of the converter under different operating conditions.

[0049] Secondly, embodiments of this application provide a converter, the converter including: an inductor, a power switch and a freewheeling switch, and a control circuit according to the above embodiments.

[0050] The converter proposed in this application embodiment receives the converter's feedback signal, compensation signal, and ripple signal respectively through the aforementioned control circuit. Therefore, this application embodiment achieves separate transmission of multiple signals by receiving the converter's feedback signal, compensation signal, and ripple signal separately through the control circuit. Furthermore, the generation units for the feedback signal, compensation signal, and ripple signal are independent of each other, allowing for independent adjustment of the compensation signal by the compensation resistor, thus increasing the system's dynamics and stability. Secondly, by superimposing the converter's feedback signal and the ripple signal to obtain the first comparison signal, and by superimposing the compensation signal and the second reference voltage signal to obtain the second comparison signal, the phase difference between the switch's control signal and the inductor current can be improved, enhancing system stability. The technical solution proposed in this application embodiment, due to the independent acquisition of the ripple signal and compensation signal, has a wide range of applicability. Moreover, through the control scheme of this application, the overall system stability is good, and the response speed is fast. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of the control circuit of a converter in related technologies;

[0053] Figure 2 This is a schematic diagram of the control circuit of a converter according to one embodiment of this application;

[0054] Figure 3 This is a waveform diagram of the control signal of the converter in related technologies;

[0055] Figure 4 This is a waveform diagram of the ripple signal proposed in the embodiments of this application;

[0056] Figure 5 This is a schematic diagram of the control circuit of a converter according to another embodiment of this application;

[0057] Figure 6 This is a schematic diagram of the control circuit of a converter according to another embodiment of this application;

[0058] Figure 7 This is a schematic diagram of the structure of a ripple signal generation unit proposed in one embodiment of this application. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0060] Converters are generally used to convert input voltage V in Converted to the desired output voltage V out Generally, this is achieved through the converter's output feedback signal FB and reference signal V. ref0 The error signal is obtained by amplifying the error through amplifier EA, and the working state of the switching transistor is controlled according to the error signal to ensure that the power supply system has high reliability and stability during operation. Therefore, it is widely used in various power supply-related application scenarios.

[0061] In applications such as DC UPS systems and power battery formation systems, the dynamic requirements for output voltage are typically low, while the requirements for output voltage reliability and current control are high. Therefore, these applications generally employ current-based control strategies. This effectively limits inductor current, improving system reliability, and enables constant-current charging and discharging of the battery. Thus, to respond promptly to voltage changes at the converter output and accurately control the switching transistors to turn on or off at appropriate times, related technologies, such as... Figure 1 As shown, a triangular wave signal associated with the inductor current information can be obtained by setting up a triangular wave generation circuit 10, and the compensation signal V is obtained by superimposing the error signal and the associated signal of the inductor current. comp The comparator CPA compares the compensation signal V. comp The output feedback signal FB is fed back and the comparison result is output to the controller 20. Finally, the controller 20 controls the conduction of the switching transistors Q1 and Q2.

[0062] However, this control method has some limitations. The main problem is that the superposition of the error signal and the associated signal of the inductor current results in excessive signal coupling. Therefore, there is not only the risk of signal interference between the associated signal of the inductor current and the error signal, but it also cannot be used to compensate for the controller generated by the external circuit. This reduces the flexibility of the converter control method and limits the applicability of the converter.

[0063] This application provides a control circuit for a converter, which can be applied to power supply devices with voltage conversion functions, such as converters and chargers. Figure 2As shown, the converter includes an inductor L1, a power switch M1 and a freewheeling switch M2, and the control circuit includes a compensation signal generation unit 110, a ripple signal generation unit 120, a comparison unit 130 and a control unit 140.

[0064] The compensation signal generation unit 110 is configured to generate a signal based on the output voltage V of the converter. out Generate compensation signal V comp The ripple signal generation unit 120 is configured to generate a ripple signal based on the control signal HS of the power switch M1 and the first reference voltage signal V. ref1 Generate ripple signal V ramp The ripple signal V ramp The phase is kept in sync with the inductor current. Comparison unit 130 is configured to compare a first comparison signal and a second comparison signal to obtain a comparison result, wherein the first comparison signal is based on the converter's feedback signal and the ripple signal V. ramp The second comparison signal is obtained by superposition based on the compensation signal V. comp With the second reference voltage signal V ref2 The feedback signal, obtained by superposition, represents either the output voltage feedback signal or the inductor current feedback signal. The control unit 140 is configured to control the power switch M1 and the freewheeling switch M2 based on the comparison result.

[0065] The control circuit provided in this embodiment receives the feedback signal and compensation signal V from the converter through the comparison unit 130. comp and ripple signal V ramp Based on the converter's feedback signal and compensation signal V comp and ripple signal V ramp The comparison result is output to control M1 and the freewheeling switch M2. Therefore, in this embodiment, the comparison unit receives the converter's feedback signal and compensation signal V through different input terminals. comp and ripple signal V ramp This enables the separate transmission of multiple signals, and includes feedback signals and compensation signals V. comp and ripple signal V ramp The generation units are independent of each other, allowing for independent adjustment of the compensation signal by the compensation resistor, increasing the system dynamic adjustment of the converter and improving its stability. Secondly, by combining the converter's feedback signal with the ripple signal V... ramp The first comparison signal is obtained by superposition, and the compensation signal V is obtained by superposition. comp With the second reference voltage signal V ref2Superimposing the second comparison signal can improve the phase difference between the switch control signal and the inductor current, thereby enhancing system stability. Furthermore, the technical solution proposed in this application, due to the independent acquisition of the ripple signal and the compensation signal, has a wide range of applicability, and the control scheme of this application results in good overall system stability and faster response speed.

[0066] In some embodiments of this application, such as Figure 2 As shown, when the converter operates in voltage-mode or current-mode control, the ripple signal generation unit 120 includes a first current source 121, a first switch S1, a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. The output current of the first current source 121 is determined based on the input voltage of the converter. The first terminal of the first switch S1 is connected to the positive terminal of the first current source 121. The first switch S1 is turned off or on based on the control signal HS of the power switch M1. The first terminal of the first resistor R1 is connected to the second terminal of the first switch S1, and the second terminal of the first resistor R1 is grounded. The first terminal of the second resistor R2 is adapted to be connected to the first reference voltage signal V. ref1 The first terminal of the first capacitor C1 is connected to the second terminal of the first switch S1, and the second terminal of the first capacitor C1 is connected to the second terminal of the second resistor R2, and has a first node. The first terminal of the second capacitor C2 is grounded, and the second terminal of the second capacitor C2 is connected to the first node. The first node is used to provide the ripple signal V. ramp .

[0067] In related technologies, such as Figure 3 As shown, SW is the signal waveform at the connection node between the power switch M1 and the freewheeling switch M2. The inductor current of inductor L1 is a triangular wave. However, the current sampling signal obtained by sampling the inductor current is generally approximately a sine wave, which has a large delay compared to the actual inductor current. If the current sampling signal is directly used as the feedback signal, the accuracy of the control signal will be reduced, which will affect the stability of the converter.

[0068] Therefore, in this embodiment, the ripple signal V is provided by the ripple signal generation unit 120 described above. ramp ,like Figure 4 As shown, the ripple signal V ramp The current sampling signal and the ripple signal V have the same waveform in phase with the inductor current. ramp Superposition as a feedback signal can effectively improve the phase difference between the control signal and the inductor current, thereby improving the stability of the converter.

[0069] Furthermore, in some embodiments of this application, the ripple signal V ramp It is directly proportional to the inductor current.

[0070] Specifically, in the embodiments of this application, the optimal current value of the first current source 121 is I1 = gm1 * V. IN Where gm1 is the line conductance of the ripple signal generation unit 120, the average voltage of the first resistor R1 in one switching cycle is as shown in the following formula (1):

[0071] VR1 = D * gm1 * V IN *R1=gm1*V OUT *R1 formula (1)

[0072] In the formula, D is the duty cycle of one switching cycle.

[0073] Therefore, the current flowing through the first resistor R1 is gm1*V OUT Furthermore, in this embodiment, the resistance value of the second resistor R2 is very large. Therefore, when the first switch S1 is on, the current flowing into the second capacitor C2 is approximately equal to gm1*(V). IN -V OUT This causes the voltage across the second capacitor C2 to increase, and the slope of this increase is gm1*(V). IN -V OUT ) / C2, and when the first switch S1 is off, the current flowing out of the second capacitor C2 is approximately equal to gm1*V OUT Consequently, the voltage across the second capacitor C2 decreases, and the slope of this decrease is gm1*V. OUT / C2. Therefore, the ripple signal V ramp It is in phase with the inductor current and has a linear proportional relationship.

[0074] Therefore, this application uses a charging and discharging circuit composed of a first current source 121, a first switch S1, a first resistor R1, and a second resistor R2, and combines the control signal HS of the power switch transistor M1 with the first reference voltage signal V. ref1 The control circuit charges and discharges the first capacitor C1 and the second capacitor C2 to generate a ripple signal V at the first node that is in phase with the inductor current. ramp Therefore, the ripple signal V can be utilized. ramp The delay of the inductor current signal is compensated, and the phase difference between the control signal HS and the inductor current is improved, thereby greatly improving the stability of the converter.

[0075] In some embodiments of this application, such as Figure 2 As shown, the compensation signal generation unit 110 includes a third resistor R3, a fourth resistor R4, an error amplifier U1, and a compensation capacitor C. com and compensation resistor R comIn this circuit, the first terminal of the third resistor R3 is connected to the output terminal of the converter, the first terminal of the fourth resistor R4 is connected to the second terminal of the third resistor R3 and has a second node, the second terminal of the fourth resistor R4 is grounded, and the positive input terminal of the error amplifier U1 is adapted to connect to the third reference voltage signal V. ref3 The negative input terminal of error amplifier U1 is connected to the second node, and the output terminal of error amplifier U1 is used to output the compensation signal V. comp Compensation capacitor C com The first terminal is connected to the output terminal of the error amplifier U1, and the compensation resistor R com The first terminal is connected to the compensation capacitor C com The second terminal is connected to the compensation resistor R. com The second end is grounded.

[0076] Specifically, the aforementioned compensation signal generation unit 110 uses the third resistor R3 and the fourth resistor R4 to sample the output voltage at the converter output terminal, and inputs the sampled output voltage feedback signal FB into the negative input terminal of the error amplifier U1. The positive input terminal of the error amplifier U1 is connected to the third reference voltage signal V. ref3 Error amplifier U1 will be based on FBFB and the third reference voltage signal V ref3 Generate compensation signal V comp The result is output from the output of the error amplifier U1 to the comparison unit 130.

[0077] Therefore, this application can effectively compensate the output voltage of the converter through the compensation signal generation unit 110, which is beneficial to improving the stability and anti-interference ability of the converter and ensuring the reliable operation of the converter under different operating conditions.

[0078] Furthermore, in the embodiments of this application, the second reference voltage signal V ref2 According to the first reference voltage signal V ref1 The size is set. It should be noted that the second reference voltage signal V... ref2 It can be set to be related to the first reference voltage signal V ref1 Equal voltage values ​​can also be based on the first reference voltage signal V. ref1 The voltage value fluctuates within a preset range.

[0079] This application embodiment is based on a first reference voltage signal V. ref1 Set the corresponding second reference voltage signal V ref2 This eliminates the first reference voltage V. ref1 For ripple signal V ramp This reduces the impact of [the changes], thereby improving the system stability of the converter.

[0080] In this embodiment, the compensation signal V is achieved through the comparison unit 130 described above.comp and ripple signal V ramp Decoupling, such as Figure 2 As shown, the comparison unit 130 includes a comparator U2, which is configured to compare the converter's feedback signal with the ripple signal V. ramp Superimpose the signals to obtain the first comparison signal, and then use the compensation signal V. comp With the second reference voltage signal V ref2 The signals are superimposed to obtain a second comparison signal, and the first and second comparison signals are compared to obtain a comparison result. Specifically, comparator U2 includes a first positive input terminal, a second positive input terminal, a first negative input terminal, and a second negative input terminal, wherein the first positive input terminal is adapted to receive the compensation signal V. comp The second positive input terminal is adapted to receive the second reference voltage signal V. ref2 The first negative input terminal is suitable for receiving the feedback signal from the converter, and the second negative input terminal is suitable for receiving the ripple signal V. ramp .

[0081] It should be noted that, in the embodiments of this application, the first negative input terminal is adapted to receive a feedback voltage signal FB used to characterize the output voltage feedback signal of the converter, that is, the feedback voltage signal FB is obtained by sampling through the third resistor R3 and the fourth resistor R4 at the output terminal of the converter.

[0082] This application embodiment receives a feedback voltage signal FB, which characterizes the output voltage feedback signal of the converter, to perform precise voltage-type control of the converter based on the voltage change at the output terminal. This enables the control circuit to be adapted to converters operating in voltage-type control mode, thereby simplifying the control circuit structure of the converter and improving the response speed of the converter.

[0083] Therefore, the comparator proposed in this application receives the compensation signal V through multiple different input terminals. comp Second reference voltage signal V ref2 Feedback signal and ripple signal V ramp To achieve the compensation signal V comp and ripple signal V ramp Decoupling between them allows the feedback signal and the compensation signal V to be decoupled. comp and ripple signal V ramp The generation units are independent of each other, which not only improves the flexibility of the converter control circuit, but also reduces the feedback signal and compensation signal V. comp and ripple signal V ramp Interference between them.

[0084] Furthermore, in some embodiments of this application, when the second comparison signal is greater than the first comparison signal, the comparison result output by comparator U2 is used to indicate the turn-on of power switch M1 and the turn-off of freewheeling switch M2, that is, in the case of compensation signal V... comp With the second reference voltage signal V ref2 The sum of these is greater than the sum of the feedback signal and the ripple signal V. ramp When the sum is equal, the output of comparator U2 will output a drive signal to indicate the turn-on of power switch M1 and the turn-off of freewheeling switch M2.

[0085] In order to make the control circuit proposed in this application applicable to converters operating in current-mode control to meet the requirements of current control, in this application embodiment, the first negative input terminal is adapted to receive a current sampling signal for characterizing the inductor current feedback signal of the converter.

[0086] Therefore, this application embodiment receives a current sampling signal used to characterize the inductor current feedback signal of the converter, so as to perform precise current-type control of the converter based on the current change at the output terminal, making the control circuit applicable to converters operating in current-type control mode, thereby effectively limiting the inductor current and improving the reliability of the converter.

[0087] For converters operating in current-mode control, especially in high-current converter applications, the resistance value of the current sampling resistor is generally very small in order to reduce power consumption and heat loss on the sampling resistor. This results in a weak sampling signal that is easily affected by external switching noise.

[0088] Therefore, in order to address the problem of weak sampling signals at the output when the converter operates in current-mode control, in the embodiments of this application, such as Figure 5 As shown, the control circuit also includes a current sampling unit 150, which is configured to sample the inductor current of the converter to obtain a current sampling signal.

[0089] Specifically, the current sampling unit 150 includes a current sampling resistor RS, a low-pass filter 151, and an operational amplifier U3. The current sampling resistor RS is connected between the inductor L1 and the output terminal of the converter. The first input terminal of the low-pass filter 151 is connected to the first terminal of the current sampling resistor RS, and the second input terminal of the low-pass filter 151 is connected to the second terminal of the current sampling resistor RS. The positive input terminal of the operational amplifier U3 is connected to the first output terminal of the low-pass filter 151, and the negative input terminal of the operational amplifier U3 is connected to the second output terminal of the low-pass filter 151. The output terminal of the operational amplifier U3 is connected to the first negative input terminal of the comparator U2, so as to send the current sampling signal to the comparator U2.

[0090] Therefore, this embodiment of the application solves the problem of weak sampling signals and susceptibility to external switching noise in high-current converters by using the current sampling unit 150. A low-pass filter is used to filter the current sampling signal passing through the current sampling resistor, and an operational amplifier is used to amplify the filtered current sampling signal to improve the sampling effect of the output signal. Furthermore, since the response bandwidth of the operational amplifier U3 is limited, it can only effectively amplify signals within a specific frequency range. For signals with frequencies higher than its bandwidth, its amplification gain will decrease, which also serves as a low-pass filter to some extent. Therefore, using the operational amplifier U3 not only improves the problem of weak sampling signals and susceptibility to external switching noise in high-current converters, but also greatly enhances the noise immunity of the current sampling unit 150, thereby facilitating the converter's fast and accurate response to output voltage fluctuations.

[0091] In the embodiments of this application, such as Figure 2 , Figures 5 to 7 As shown, the control unit 140 includes an RS flip-flop 141, wherein one of the set terminal S and the reset terminal R of the RS flip-flop 141 is connected to the output terminal of the comparator unit 130, the first output terminal Q of the RS flip-flop 141 is connected to the gate of the power switch M1, and the second output terminal of the RS flip-flop 141 is connected to the gate of the power switch M1. Connect the gate of the freewheeling switch M2.

[0092] Therefore, in this embodiment, the RS flip-flop generates a stable control signal HS based on the output signal of the comparison unit to ensure that the power switch and the freewheeling switch are turned on or off at the appropriate time, thereby achieving efficient and accurate voltage regulation control.

[0093] Specifically, such as Figure 2 and Figure 5 As shown, when the converter operates in voltage-mode or current-mode control, the set terminal S of the RS flip-flop 141 is connected to the output terminal of the comparator unit 130.

[0094] When the converter operates in voltage-mode or current-mode control, the reset terminal R of RS flip-flop 141 is connected to the duty cycle signal ton. If the aforementioned compensation signal V... comp With the second reference voltage signal V ref2 The sum of these is greater than the sum of the feedback signal and the ripple signal V. ramp The sum of these values ​​results in a high-level output from comparator U2, which is then sent to the set input S of RS flip-flop 141. This causes the first output Q to generate a high-level first drive signal HS, controlling the power switch to turn on and triggering the second output... A low-level second drive signal LS is generated to control the freewheeling switch M2 to turn off.

[0095] Therefore, in this embodiment of the application, the output terminal of the comparator is connected to the set terminal S of the RS flip-flop 141, so as to realize that in voltage-type control mode or current-type control mode, the power switch transistor can be turned on quickly and accurately according to the voltage or current change at the output terminal of the converter, and the freewheeling switch transistor can be turned off, thereby effectively maintaining the stability of the output voltage of the converter.

[0096] like Figure 6 and Figure 7 As shown, when the converter operates in a fixed-frequency peak current control mode, the reset terminal R of the RS flip-flop 141 is connected to the output terminal of the comparator unit 130.

[0097] When the converter operates in a fixed-frequency peak current control mode, the set input S of the RS flip-flop 141 is connected to the clock signal CLK. If the aforementioned compensation signal V... comp With the second reference voltage signal V ref2 The sum of these is greater than the sum of the output signal and the ripple signal V. ramp The sum of these values ​​results in a high-level output from comparator U2, which is then sent to the reset terminal R of RS flip-flop 141. This causes the first output Q to generate a low-level first drive signal HS, which controls the power switch to turn off and also causes the second output Q to... A high-level second drive signal LS is generated to control the freewheeling switch M2 to turn on.

[0098] Therefore, in this embodiment of the application, the output terminal of the comparator is connected to the reset terminal R of the RS flip-flop 141, so as to realize that in the fixed frequency peak current type control mode, when the current at the output terminal of the converter reaches the peak value, the power switch transistor can be turned off quickly and accurately and the freewheeling switch transistor can be turned on, thereby effectively maintaining the stability of the output voltage of the converter.

[0099] Furthermore, since subharmonic oscillations may occur if the duty cycle is large when the converter operates in a fixed-frequency peak current control mode, in this embodiment, the ripple signal generation unit 120 further includes a second current source 122, a second switch S2, and a third capacitor C3. The output current of the second current source 122 is determined according to the converter's output voltage V. out It is determined that the first terminal of the second switch S2 is connected to the positive terminal of the second current source 122, and the second switch S2 is turned off or closed based on the control signal HS of the power switch tube M1. The first terminal of the third capacitor C3 is connected to the second terminal of the second switch S2, and the second terminal of the second capacitor C3 is connected to the aforementioned first node.

[0100] Specifically, the optimal value of the current in the second current source 122 is I2 = gm2 * V. out Furthermore, the ripple signal V ramp The sawtooth wave is written as gm2*Vout / C1, the sawtooth wave slope varies with the output voltage V out The voltage rises with the increase of the duty cycle. Therefore, this application uses a charging and discharging circuit composed of a second current source 122 and a second switch S2 to charge and discharge the third capacitor C3 according to the control signal HS of the power switch tube, so as to generate a sawtooth wave to solve the harmonic oscillation problem that may be generated in the fixed frequency peak current type control mode, thereby effectively improving the noise immunity of the converter and further improving the stability of the converter.

[0101] Accordingly, this application also provides a converter, wherein the converter includes an inductor L1, a power switch M1, a freewheeling switch M2, and a control circuit according to the above embodiments.

[0102] The specific configurations and further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0103] The converter proposed in this embodiment receives the converter's feedback signal and compensation signal V through the aforementioned control circuit. comp and ripple signal V ramp Therefore, in this embodiment, the control circuit receives the feedback signal and compensation signal V from the converter, respectively. comp and ripple signal V ramp This enables the separate transmission of multiple signals, and includes feedback signals and compensation signals V. comp and ripple signal V ramp The generation units are independent of each other, allowing for independent adjustment of the compensation signal by the compensation resistor, thus increasing the system's dynamics and stability. Secondly, by combining the feedback signal of the converter with the ripple signal V... ramp The first comparison signal is obtained by superimposing the compensation signal V. comp With the second reference voltage signal V ref2 By superimposing the second comparison signal, the phase difference between the switch control signal and the inductor current can be improved, thereby enhancing system stability. The technical solution proposed in this application, due to the ripple signal V... ramp and compensation signal V comp The circuit is independently obtainable, has a wide range of applications, and through the control scheme of this application, the overall system has good stability and fast response speed.

[0104] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0105] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0106] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0107] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0108] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A control circuit for a converter, characterized in that, The converter includes an inductor, a power switch, and a freewheeling switch; the control circuit includes: A compensation signal generation unit is configured to generate a compensation signal based on the output voltage of the converter. A ripple signal generation unit is configured to generate a ripple signal based on the control signal of the power switch and a first reference voltage signal, wherein the ripple signal is in phase with the inductor current. A comparison unit is configured to compare a first comparison signal and a second comparison signal to obtain a comparison result, wherein the first comparison signal is obtained by superimposing the feedback signal of the converter with the ripple signal, the second comparison signal is obtained by superimposing the compensation signal with the second reference voltage signal, and the feedback signal represents an output voltage feedback signal or an inductor current feedback signal. A control unit configured to control the power switch and the freewheeling switch based on the comparison result.

2. The control circuit according to claim 1, characterized in that, The second reference voltage signal is set according to the magnitude of the first reference voltage signal.

3. The control circuit according to claim 2, characterized in that, The ripple signal is directly proportional to the inductor current.

4. The control circuit according to claim 2, characterized in that, The comparison unit includes a comparator, which includes a first positive input terminal, a second positive input terminal, a first negative input terminal, and a second negative input terminal. Wherein, the first positive input terminal is adapted to receive the compensation signal, the second positive input terminal is adapted to receive the second reference voltage signal, the first negative input terminal is adapted to receive the feedback signal of the converter, and the second negative input terminal is adapted to receive the ripple signal.

5. The control circuit according to claim 4, characterized in that, The first negative input terminal is adapted to receive a feedback voltage signal used to characterize the output voltage feedback signal of the converter.

6. The control circuit according to claim 4, characterized in that, The first negative input terminal is adapted to receive a current sampling signal used to characterize the inductor current feedback signal of the converter.

7. The control circuit according to claim 6, characterized in that, The control circuit further includes a current sampling unit configured to sample the inductor current of the converter to obtain the current sampling signal.

8. The control circuit according to claim 7, characterized in that, The current sampling unit includes: A current sampling resistor is connected between the inductor and the output terminal of the converter; A low-pass filter, wherein the first input terminal of the low-pass filter is connected to the first terminal of the current sampling resistor, and the second input terminal of the low-pass filter is connected to the second terminal of the current sampling resistor; An operational amplifier is provided, wherein the positive input terminal of the operational amplifier is connected to the first output terminal of the low-pass filter, the negative input terminal of the operational amplifier is connected to the second output terminal of the low-pass filter, and the output terminal of the operational amplifier is connected to the first negative input terminal of the comparator, so as to send the current sampling signal into the comparator.

9. The control circuit according to any one of claims 1-8, characterized in that, The control unit includes an RS flip-flop, one of the set terminal and the reset terminal of the RS flip-flop is connected to the output terminal of the comparator unit, the first output terminal of the RS flip-flop is connected to the gate of the power switch, and the second output terminal of the RS flip-flop is connected to the gate of the freewheeling switch.

10. The control circuit according to claim 9, characterized in that, When the converter operates in voltage-mode or current-mode control, the set terminal of the RS flip-flop is connected to the output terminal of the comparator unit.

11. The control circuit according to claim 9, characterized in that, When the converter operates in a fixed-frequency peak current control mode, the reset terminal of the RS flip-flop is connected to the output terminal of the comparator unit.

12. The control circuit according to claim 1, characterized in that, When the converter operates in voltage-mode or current-mode control, the ripple signal generation unit includes: A first current source, the output current of which is determined based on the input voltage of the converter; A first switch, the first end of which is connected to the positive terminal of the first current source, and the first switch is turned off or closed based on the control signal of the power switch tube; A first resistor, the first end of which is connected to the second end of the first switch, and the second end of the first resistor is grounded; A second resistor, the first end of which is adapted to be connected to a first reference voltage signal; A first capacitor, wherein a first terminal of the first capacitor is connected to a second terminal of the first switch, a second terminal of the first capacitor is connected to a second terminal of the second resistor, and has a first node; The second capacitor has its first terminal grounded and its second terminal connected to the first node, which provides the ripple signal.

13. The control circuit according to claim 12, characterized in that, When the converter needs to operate in a constant-frequency peak current control mode, the ripple signal generation unit further includes: The second current source, the output current of which is determined according to the output voltage of the converter; The second switch has its first end connected to the positive terminal of the second current source, and the second switch is turned off or closed based on the control signal of the power switch tube. The third capacitor has its first end connected to the second end of the second switch, and the second end of the second capacitor is connected to the first node.

14. The control circuit according to any one of claims 1-8, characterized in that, The compensation signal generation unit includes: The third resistor, the first end of which is connected to the output terminal of the converter; A fourth resistor, wherein the first end of the fourth resistor is connected to the second end of the third resistor and has a second node, and the second end of the fourth resistor is grounded; An error amplifier is provided, wherein the positive input terminal of the error amplifier is adapted to receive a third reference voltage signal, the negative input terminal of the error amplifier is connected to the second node, and the output terminal of the error amplifier is used to output the compensation signal. A compensation capacitor, the first end of which is connected to the output terminal of the error amplifier; A compensation resistor, the first end of which is connected to the second end of the compensation capacitor, and the second end of the compensation resistor is grounded.

15. A converter, characterized in that, The converter includes: Inductors, power switches, and freewheeling switches; The control circuit according to any one of claims 1-14.

Images