Time sequence control method and system for controlling switching converter

Abstract

The invention relates to the technical field of switching power supplies, in particular to a sequential control method and system for controlling a switching converter, and the method comprises the steps: initializing a pulse width modulation controller and a power switch tube and a fly-wheel diode of the switching converter, collecting output voltage, calculating an error signal, and amplifying to obtain a control signal; the clock signal triggers a pulse width modulation controller period, generates a sawtooth wave signal, adjusts a duty ratio and generates a pulse width modulation signal; the pulse width modulation signal is amplified by the driving circuit and controls the on and off of the power switch tube; according to the method, the duty ratio is dynamically adjusted through the closed-loop feedback, the output stability and the energy transmission efficiency are balanced, the output voltage and the inductive current can be fed back at the same time, the anti-interference capability is high, the loop is stable, and the energy transmission efficiency is improved. The dynamic response is fast.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a timing control method and system for controlling switching converter. BACKGROUND

[0002] Switching power supply has been widely used in many fields such as consumer electronics, industrial control, and new energy due to its high efficiency, high power density, and wide input and output voltage range. In these applications, it is necessary to accurately control the timing of the switching converter to achieve stable output voltage and current, and meet the power supply requirements of different devices.

[0003] Traditional switching converter control methods, such as voltage mode control and current mode control, can achieve stable control of output voltage to some extent, but have some limitations. For example, the dynamic response speed of voltage mode control is slow, and its adaptability to input voltage and load changes is limited. Although the dynamic response of current mode control is improved, there are still loop stability problems, especially when the input voltage and output voltage are close in value, which can easily lead to loop instability, resulting in output voltage containing ripple interference signals and audio noise, affecting the normal operation of switching power supply and powered devices. SUMMARY

[0004] The purpose of the present application is to provide a timing control method and system for controlling switching converter, aiming to solve the problem of traditional switching converter control method being easily disturbed by signal and audio noise and poor loop stability.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a timing control method for controlling switching converter, comprising the following steps: Initializing the pulse width modulation controller and the power switch tube and freewheeling diode of the switching converter, collecting the output voltage, calculating the error signal, amplifying, and obtaining the control signal; The clock signal triggers the pulse width modulation controller periodically to generate a sawtooth wave signal, adjusts the duty cycle, and generates a pulse width modulation signal; The pulse width modulation signal is amplified by the drive circuit and controls the conduction and turn-off of the power switch tube; Repeat the collection of the output voltage, error amplification, pulse width modulation, and control of the conduction and turn-off of the power switch tube to form a closed-loop feedback and correct the error to stabilize the output.

[0006] The specific way of initializing the pulse width modulation controller and the power switch tube and freewheeling diode of the switching converter, collecting the output voltage, calculating the error signal, amplifying, and obtaining the control signal is as follows: Setting a reference voltage, a reference current, an over-voltage threshold and an over-current threshold, initializing a clock frequency and a period of a pulse width modulation controller, configuring initial states of power switch tubes and freewheeling diodes of a switching converter; Real-time acquisition of an output voltage by an analog-to-digital converter, calculation of an error signal based on the output voltage and the reference voltage; Amplification of the error signal by an error amplifier to obtain a control signal.

[0007] The clock signal triggers the pulse width modulation controller periodically to generate a sawtooth signal, adjusts a duty cycle, and generates a pulse width modulation signal in the following specific manner: The clock signal triggers the pulse width modulation controller periodically to generate a sawtooth signal. The control signal is compared with the sawtooth signal to obtain a comparison result. The duty cycle is updated according to the latest sawtooth signal every clock cycle to generate a pulse width modulation signal.

[0008] The comparison result includes that the control signal is greater than the sawtooth signal, the pulse width modulation controller outputs a high level, the power switch tube is turned on, the control signal is less than the sawtooth signal, the pulse width modulation controller outputs a low level, and the power switch tube is turned off.

[0009] The over-voltage threshold is 1.2 times the reference voltage.

[0010] The over-current threshold is 1.2 times the reference current.

[0011] In a second aspect, the present application further provides a timing control system for controlling a switching converter, which is applied to the timing control method for controlling a switching converter as described in the first aspect above, and includes a control module, an acquisition circuit module, a driving circuit module, a protection circuit module and a clock circuit module, wherein the control module is connected with the acquisition circuit module, the driving circuit module, the protection circuit module and the clock circuit module respectively. The control module is configured to generate a pulse width modulation signal and execute a closed-loop control algorithm. The acquisition circuit module is configured to acquire an output voltage and a current. The driving circuit module is configured to amplify the pulse width modulation signal and drive a power switch tube. The protection circuit module is configured to detect over-voltage, over-current and over-heat, and trigger a hardware interrupt to turn off the pulse width modulation controller output. The clock circuit module is configured to provide a fixed frequency clock signal to determine a switching frequency of the pulse width modulation controller.

[0012] The timing control method for controlling the switching converter provided by the present application initializes the pulse width modulation controller and the power switch tube and freewheeling diode of the switching converter, collects the output voltage, calculates the error signal, amplifies it to obtain the control signal; the clock signal triggers the pulse width modulation controller periodically to generate the sawtooth signal, adjust the duty cycle, and generate the pulse width modulation signal; the pulse width modulation signal is amplified by the driving circuit and controls the turn-on and turn-off of the power switch tube; the collection of the output voltage, the error amplification, the pulse width modulation, and the control of the turn-on and turn-off of the power switch tube are repeated to form a closed loop feedback, correct the error, and stabilize the output. This method dynamically adjusts the duty cycle through the closed loop feedback, balances the output stability and energy transmission efficiency, can simultaneously feedback the output voltage and inductance current, has strong anti-interference ability, stable loop, fast dynamic response, and solves the problems of traditional switching converter control methods, such as easy interference by signal and audio noise and poor loop stability. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0014] Figure 1 is a flow chart of the timing control system for controlling the switching converter provided by the present application.

[0015] Figure 2 is a flow chart of the specific way of initializing the pulse width modulation controller and the power switch tube and freewheeling diode of the switching converter, collecting the output voltage, calculating the error signal, amplifying it to obtain the control signal.

[0016] Figure 3 is a flow chart of the specific way of the clock signal triggering the pulse width modulation controller periodically to generate the sawtooth signal, adjust the duty cycle, and generate the pulse width modulation signal.

[0017] Figure 4 is a schematic diagram of the timing control system for controlling the switching converter provided by the present application.

[0018] In the figure: 1-control module, 2-acquisition circuit module, 3-driving circuit module, 4-protection circuit module, 5-clock circuit module. DETAILED DESCRIPTION

[0019] Embodiments of the present application are described below by way of example with reference to the accompanying drawings, in which like or similar elements and / or features are identified by the same or similar reference signs, and of which: Figures 1 to 3 show schematic diagrams of a switching converter according to embodiments of the present application; and Figure 4 shows a flow chart of a timing control method for a switching converter according to embodiments of the present application.

[0020] Referring to Figures 1 to 3 , in a first aspect, the present application provides a timing control method for a switching converter, comprising the following steps: S1 initializing a pulse width modulation controller and power switches and freewheeling diodes of the switching converter, collecting an output voltage, calculating an error signal, amplifying to obtain a control signal; Specifically, S11 setting a reference voltage, a reference current, an over-voltage threshold and an over-current threshold, initializing a clock frequency and a period of the pulse width modulation controller, configuring initial states of the power switches and the freewheeling diodes of the switching converter; In embodiments of the present application, a reference voltage Vref, a reference current Irated, an over-voltage threshold Vmax and an over-current threshold Imax are set, Vmax = 1.2Vref, Imax = 1.2Irated, the over-voltage threshold and the over-current threshold are used to trigger a turn-off pulse width modulation (PWM) signal by hardware or software, a clock frequency fclk and a period T = 1 / fclk of the PWM controller are initialized, the period T is used to determine an update rate of a subsequent PWM signal, initial states of power switches (e.g. MOSFET) and freewheeling diodes / switches of a switching converter topology (e.g. Buck converter) are configured (usually initially turned off).

[0021] S12 collecting an output voltage in real time by an analog-to-digital converter, calculating an error signal based on the output voltage and the reference voltage; In embodiments of the present application, an output voltage Vout is collected by an analog-to-digital converter (ADC), Vout is compared with Vref, and an error signal Verror = Vref Vout is calculated.

[0022] S13 amplifying the error signal by an error amplifier to obtain a control signal.

[0023] In embodiments of the present application, the error signal is amplified by an error amplifier (EA) to generate a control signal Vctrl, which is used to adjust a PWM duty cycle.

[0024] S2 a clock signal triggers the pulse width modulation controller periodically to generate a sawtooth signal, adjust a duty cycle, and generate a pulse width modulation signal; Specifically, S21 the clock signal triggers the pulse width modulation controller period, generating sawtooth signal; In the embodiment of the application, the clock signal (CLK) triggers the PWM period to start, generating a sawtooth signal Vsaw (period T, peak Vsaw-max), which is used as a carrier signal for PWM modulation.

[0025] S22 compares the control signal with the sawtooth signal, and obtains a comparison result; In the embodiment of the application, the control signal Vctrl is compared with the sawtooth signal Vsaw: When Vctrl>Vsaw, the PWM output is high (power switch tube is turned on), and the on time ton=D T.

[0026] When Vctrl≤Vsaw, the PWM output is low (power switch tube is turned off), and the off time toff=(1 D) T.

[0027] S23 adjusts and updates the duty cycle according to the latest sawtooth signal in each clock cycle, and generates a pulse width modulation signal.

[0028] In the embodiment of the application, the duty cycle D is adjusted according to the latest Vctrl in each clock cycle.

[0029] S3 the pulse width modulation signal is amplified by a driving circuit, and controls the on and off of the power switch tube; In the embodiment of the application, taking a Buck converter as an example: on phase (ton): the input voltage Vin charges the inductor L through the on MOSFET, the inductor current iL rises linearly, and the energy is stored in the inductor and the capacitor C. Off phase (toff): the MOSFET is turned off, the inductor releases energy through the freewheeling diode (Diode), maintains the output current, and the inductor current iL decreases linearly, wherein the input voltage Vin is the power input of the switching converter, and the inductor current iL reflects the state of energy transmission.

[0030] S4 repeats the collection of the output voltage, error amplification, pulse width modulation, control of the on and off of the power switch tube, forms a closed-loop feedback, and corrects the error to stabilize the output.

[0031] In the embodiment of the present application, steps S12, S13, S2, S3 are repeated to form a closed loop feedback system: output voltage sampling→error amplification→PWM modulation→power stage regulation→output voltage change. When the load or input voltage changes, the closed loop system automatically adjusts the duty cycle D to maintain Vout≈Vref, and realizes output stability through real-time error correction.

[0032] Please refer to Figure 4 In a second aspect, the present application further provides a timing control system for controlling a switching converter, which is applied to the timing control method for controlling a switching converter as described in the first aspect above, and comprises a control module 1, a collection circuit module 2, a driving circuit module 3, a protection circuit module 4 and a clock circuit module 5, wherein the control module 1 is connected to the collection circuit module 2, the driving circuit module 3, the protection circuit module 4 and the clock circuit module 5 respectively. The control module 1 is configured to generate a pulse width modulation signal and execute a closed loop control algorithm. The collection circuit module 2 is configured to collect an output voltage and a current. The driving circuit module 3 is configured to amplify the pulse width modulation signal and drive a power switch tube. The protection circuit module 4 is configured to detect overvoltage, overcurrent and overheating, and trigger a hardware interrupt to shut down the output of the pulse width modulation controller. The clock circuit module 5 is configured to provide a fixed frequency clock signal to determine the switching frequency of the pulse width modulation controller.

[0033] In the embodiment of the present application, the control module 1 (such as an MCU, a DSP or a special PWM chip, such as TI's TMS320F28335) is configured to generate a pulse width modulation signal and execute a closed loop control algorithm; the collection circuit module 2 is configured to collect an output voltage and a current; the driving circuit module 3 is configured to amplify the pulse width modulation signal and drive a power switch tube; the protection circuit module 4 is configured to detect overvoltage, overcurrent and overheating, and trigger a hardware interrupt to shut down the output of the pulse width modulation controller; and the clock circuit module 5 is configured to provide a fixed frequency clock signal to determine the switching frequency of the pulse width modulation controller.

[0034] The above only discloses a preferred embodiment of the timing control method and system for controlling a switching converter of the present application, and of course cannot limit the scope of the present application. Those skilled in the art can understand that all or part of the above-mentioned embodiments can be implemented, and equivalent changes made according to the claims of the present application still fall within the scope of the present application.

Claims

1. A timing control method of controlling a switching converter, characterized by, It comprises the following steps: initializing the pulse width modulation controller and the power switch tube and freewheeling diode of the switching converter, collecting the output voltage, calculating the error signal, amplifying, and obtaining the control signal; the clock signal triggers the pulse width modulation controller periodically, generates a sawtooth signal, adjusts the duty cycle, and generates a pulse width modulation signal; the pulse width modulation signal is amplified through the drive circuit and controls the conduction and turn-off of the power switch tube; repeating the collection of the output voltage, error amplification, pulse width modulation, and control of the conduction and turn-off of the power switch tube forms a closed-loop feedback and corrects the error to stabilize the output.

2. The timing control method of controlling a switching converter according to claim 1, It is characterized in that the specific way of initializing the pulse width modulation controller and the power switch tube and freewheeling diode of the switching converter, collecting the output voltage, calculating the error signal, amplifying, and obtaining the control signal is: setting the reference voltage, reference current, overvoltage threshold, and overcurrent threshold, initializing the clock frequency and period of the pulse width modulation controller, and configuring the initial state of the power switch tube and freewheeling diode of the switching converter; collecting the output voltage in real time through an analog-to-digital converter, and calculating the error signal based on the output voltage and the reference voltage; amplifying the error signal through an error amplifier to obtain the control signal.

3. The timing control method for controlling the switching converter as described in claim 1, It is characterized in that the specific way of the clock signal triggering the pulse width modulation controller periodically, generating a sawtooth signal, adjusting the duty cycle, and generating a pulse width modulation signal is: the clock signal triggers the pulse width modulation controller periodically, and generates a sawtooth signal; comparing the control signal with the sawtooth signal to obtain a comparison result; updating the duty cycle according to the latest sawtooth signal every clock cycle to generate a pulse width modulation signal.

4. The method of claim 3, wherein the switching frequency of the switching converter is controlled by the method. It is characterized in that the comparison result includes that the control signal is greater than the sawtooth signal, the pulse width modulation controller outputs a high level, the power switch tube is turned on, the control signal is less than the sawtooth signal, the pulse width modulation controller outputs a low level, and the power switch tube is turned off.

5. The method of claim 2, wherein the time sequence control method of controlling the switching converter is characterized by ； The overvoltage threshold is 1.2 times the reference voltage.

6. The method of claim 2, wherein the switching frequency of the switching converter is determined by the following equation: ###00003### where f is the switching frequency, f0 is the reference frequency, and k is a constant. ； The overcurrent threshold is 1.2 times the reference current.

7. A timing control system for controlling a switching converter, applied to the timing control method for controlling a switching converter according to any one of claims 1 to 6, characterized by ； It comprises a control module, an acquisition circuit module, a drive circuit module, a protection circuit module, and a clock circuit module, and the control module is connected with the acquisition circuit module, the drive circuit module, the protection circuit module, and the clock circuit module; the control module is used for generating a pulse width modulation signal and executing a closed-loop control algorithm; the acquisition circuit module is used for collecting the output voltage and current; the drive circuit module is used for amplifying the pulse width modulation signal and driving the power switch tube; the protection circuit module is used for overvoltage / overcurrent / overheat detection and triggering a hardware interrupt to turn off the pulse width modulation controller output; the clock circuit module is used for providing a fixed frequency clock signal to determine the switching frequency of the pulse width modulation controller.

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