Peak current control circuit

Abstract

The utility model relates to the technical field of power electronics, in particular to a peak current control circuit. The utility model discloses a peak current control circuit, which comprises a detection module, an error amplifier, a comparator, a voltage division module, a control signal generation module and a power switch module, one end of the detection module is used for collecting current and voltage signals of a to-be-controlled circuit, and the other end is grounded; the detection module is connected with the voltage division module and the power switch module; the non-inverting input end of the error amplifier is connected with a reference voltage, the inverting input end of the error amplifier is connected with the voltage division module, and the output end of the error amplifier is connected with the inverting input end of the comparator; the in-phase input end of the comparator is connected with the detection module and the control signal generation module. According to the utility model, the precision of current control can be improved, the dynamic response speed to the change of the input voltage is enhanced, the stability of the circuit is improved, and the technical defects existing in the traditional voltage mode control method are overcome.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power electronics, especially a peak current control circuit. BACKGROUND

[0002] In the field of power electronics, current control is a key technology. The widely used voltage mode control method has several technical defects: first, the precision of voltage control method is low, which is difficult to meet the increasing requirements of modern electronic devices on power supply performance; second, the dynamic response speed of voltage mode control to input voltage change is slow, which may cause device damage when input voltage changes suddenly; third, the stability of voltage mode control is poor, which is prone to instability in complex working environment. These problems are particularly prominent in practical application, especially in high-frequency switching power supply, due to the instability of input voltage, there are many uncertain factors in the circuit, which leads to the shortening of the service life of some devices. In the production environment, the damage of a device often leads to the stop of the whole production line, causing significant economic losses. In addition, the feedback loop compensation of the traditional voltage control method is complex, which increases the difficulty of circuit design and debugging. The existence of these problems seriously affects the reliability and service life of power electronic devices, and restricts the further development of power electronic technology. The limitations of voltage mode control make it necessary to develop a more efficient and accurate current control method. SUMMARY

[0003] The utility model aims at providing a peak current control circuit, which can improve the precision of current control, enhance the dynamic response speed to input voltage change, and improve the stability of the circuit, solving the technical defects of the traditional voltage mode control method.

[0004] To solve the above technical problems, the utility model provides a peak current control circuit, which comprises a detection module, an error amplifier, a comparator, a voltage division module, a control signal generation module and a power switch module.

[0005] One end of the detection module is used for collecting current and voltage signals of the controlled circuit, and the other end is grounded; the detection module is connected with the voltage division module and the power switch module.

[0006] The noninverting input end of the error amplifier is connected with a reference voltage, the inverting input end of the error amplifier is connected with the voltage division module, and the output end of the error amplifier is connected with the inverting input end of the comparator.

[0007] The noninverting input end of the comparator is connected with the detection module and the control signal generation module, and the output end of the comparator is connected with the control signal generation module.

[0008] The control signal generation module is connected to the power switch module.

[0009] Further, the detection module comprises an inductor and a first resistor.

[0010] One end of the inductor is connected to a circuit to be controlled, and the other end is connected to the power switch module; one end of the first resistor is connected to the power switch module and the non-inverting input terminal of the comparator, and the other end is grounded.

[0011] Further, the power switch module comprises a MOS tube, a diode and a capacitor.

[0012] The source of the MOS tube is connected to the other end of the inductor and one end of the diode, the drain is connected to the first resistor, and the gate is connected to the control signal generation module; the other end of the diode is connected to the capacitor and one end of the voltage division module; the other end of the capacitor is connected to the voltage division module and the other end of the first resistor.

[0013] Further, the voltage division module comprises a second resistor and a third resistor.

[0014] One end of the second resistor is connected to the diode and one end of the capacitor, and the other end of the second resistor is connected to the third resistor; the other end of the third resistor away from the second resistor is connected to the capacitor and the other end of the first resistor.

[0015] Further, the control signal generation module comprises a flip-flop, an oscillator and a slope generator.

[0016] The reset end of the flip-flop is connected to the output terminal of the comparator, the set end of the flip-flop is connected to the oscillator, and the output terminal of the flip-flop is connected to the gate of the MOS tube; the oscillator is connected to the slope generator; the slope generator is connected to the non-inverting input terminal of the comparator.

[0017] Further, an adder is arranged between the slope generator and the comparator, which is used for performing addition operation on the slope compensation signal generated by the slope generator and the sampling signal collected by the detection module.

[0018] Further, when the reset end R of the flip-flop is 1 and the set end S is 0, the output terminal Q of the flip-flop is 0, and the MOS tube is turned off.

[0019] Further, when the reset end R of the flip-flop is 0 and the set end S is 1, the output terminal Q of the flip-flop is 1, and the MOS tube is turned on.

[0020] Further, the oscillator is used for sending a narrow pulse signal to the flip-flop and the slope generator.

[0021] Further, the detection module is configured to collect current and voltage signals of the to-be-controlled circuit and convert the current and voltage signals into sampling signals and transmit the sampling signals to the in-phase input end of the comparator;

[0022] The error amplifier is configured to receive a reference voltage and a feedback voltage from the voltage dividing module and amplify the difference between the reference voltage and the feedback voltage to generate a first control signal;

[0023] The control signal generation module is configured to generate a ramp compensation signal and transmit the ramp compensation signal to the in-phase input end of the comparator;

[0024] The comparator is configured to compare the sum of the sampling signal and the ramp compensation signal with the control signal;

[0025] The control signal generation module is further configured to output a second control signal to the power switch module according to the comparison result of the comparator;

[0026] The power switch module is configured to adjust the peak current in the to-be-controlled circuit according to the second control signal.

[0027] By means of the above technical solution, the utility model has the following beneficial effects:

[0028] By means of the arrangement of the detection module, the error amplifier, the comparator, the voltage dividing module, the control signal generation module and the power switch module, one end of the detection module is configured to collect current and voltage signals of the to-be-controlled circuit and the other end is grounded; the detection module is connected with the voltage dividing module and the power switch module; the in-phase input end of the error amplifier is connected with a reference voltage, the inverse input end of the error amplifier is connected with the voltage dividing module, and the output end of the error amplifier is connected with the inverse input end of the comparator; the in-phase input end of the comparator is connected with the detection module and the control signal generation module, and the output end of the comparator is connected with the control signal generation module; and the control signal generation module is connected with the power switch module. The circuit collects current and voltage signals of the to-be-controlled circuit by means of the detection module, generates a control signal by means of the error amplifier, compares signals by means of the comparator, generates a control signal by means of the control signal generation module, and adjusts the peak current by means of the power switch module, so that accurate control of the to-be-controlled circuit is realized, and the control precision is improved, the dynamic response speed is accelerated, the stability is enhanced, and the circuit design is simplified. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 FIG. 1 is a schematic diagram of the overall structure of the peak current control circuit according to an embodiment of the utility model;

[0030] Figure 2 FIG. 2 is a flowchart of the working process of the peak current control circuit according to an embodiment of the utility model. DETAILED DESCRIPTION

[0031] A peak current control circuit according to the present application will now be described in more detail below, in which the preferred embodiments of the present application are illustrated, it should be understood that all changes and modifications that one could make to the present application described herein, while still implementing the advantageous effects of the present application. Therefore, the following description should be understood as a broad knowledge for those skilled in the art, and not as a limitation of the present application.

[0032] The present application will now be described in more detail below with reference to the accompanying drawings. According to the following description, the advantages and features of the present application will be more apparent. It should be noted that the drawings are very simplified and all use non-precise proportions, only to facilitate, clear and assist the purpose of illustrating the embodiments of the present application.

[0033] As shown in Figures 1-2 The present application proposes a convenient and practical peak current control circuit, comprising a detection module, an error amplifier 1, a comparator 2, a voltage dividing module, a control signal generation module and a power switch module.

[0034] Specifically, one end of the detection module is used to collect the current and voltage signals of the controlled circuit, and the other end is connected to the ground GND1; the detection module is connected to the voltage dividing module and the power switch module; the non-inverting input terminal of the error amplifier 1 is connected to the reference voltage, the inverting input terminal of the error amplifier 1 is connected to the voltage dividing module, and the output terminal of the error amplifier 1 is connected to the inverting input terminal of the comparator 2; the non-inverting input terminal of the comparator 2 is connected to the detection module and the control signal generation module, and the output terminal of the comparator 2 is connected to the control signal generation module; the control signal generation module is connected to the power switch module. The circuit collects the current and voltage signals of the controlled circuit through the detection module, and transmits them to the error amplifier 1 and the comparator 2. The error amplifier 1 receives the reference voltage and the feedback voltage, and outputs to the comparator 2 after difference amplification. The comparator 2 compares the collected signal with the control signal, and the control signal generation module generates the control signal according to the comparison result, adjusts the power switch module, so as to realize the accurate control of the peak current of the controlled circuit. Through the cooperation of the above components, the circuit can improve the accuracy of current control, enhance the dynamic response speed to the change of input voltage, and improve the stability of the circuit, and solve the technical defects existing in the traditional voltage mode control method.

[0035] In an embodiment, the detection module comprises an inductor L1 and a first resistor R1. Specifically, one end of the inductor L1 is connected to the circuit to be controlled, and the other end is connected to the power switch module; one end of the first resistor R1 is connected to the power switch module and the non-inverting input terminal of the comparator 2, and the other end is grounded GND1. This embodiment can effectively detect the current change in the circuit to be controlled, provide an accurate current signal to the comparator 2, thereby improving the accuracy and response speed of current control.

[0036] In this embodiment, the power switch module comprises a MOS tube Q5, a diode D and a capacitor C1.

[0037] Specifically, the source of the MOS tube Q5 is connected to the other end of the inductor L1 and one end of the diode D, the drain is connected to the first resistor R1, and the gate is connected to the control signal generation module; the other end of the diode D is connected to the capacitor C1 and one end of the voltage division module; the other end of the capacitor C1 is connected to the voltage division module and the other end of the first resistor R1. The power switch module of this embodiment comprises a MOS tube Q5, a diode D and a capacitor C1, which realizes effective regulation of the current. The source of the MOS tube Q5 is connected to the inductor L1 and the diode D, so that the current induced by the inductor L1 can be transmitted through the diode D. The drain is connected to the first resistor R1, providing a current loop. The gate is connected to the control signal generation module, so that the MOS tube Q5 can be turned on or turned off according to the control signal, thereby regulating the current. The connection mode of the diode D and the capacitor C1 enables the current to be transmitted stably, and is fed back to the circuit through the voltage division module, further improving the stability and response speed of the circuit.

[0038] Specifically, the MOS tube Q5 is used as the core element of the power switch, the source of which is connected to the inductor L1 and the diode D, so that the current induced by the inductor L1 can be transmitted through the diode D. The drain is connected to the first resistor R1, forming a current path. The gate is connected to the control signal generation module, and the MOS tube Q5 is turned on and turned off through the control of the control signal generation module. The connection mode of the diode D and the capacitor C1 makes the current more stable during transmission, and is fed back through the voltage division module, further improving the stability and response speed of the circuit.

[0039] In an embodiment, the voltage division module comprises a second resistor R2 and a third resistor R3.

[0040] Specifically, one end of the second resistor R2 is connected to the diode D and one end of the capacitor C1, and the other end of the second resistor R2 is connected to the third resistor R3; the other end of the third resistor R3 away from the second resistor R2 is connected to the capacitor C1 and the other end of the first resistor R1.

[0041] The second resistor R2 and the third resistor R3 in the voltage division module of the embodiment jointly act, through reasonable resistance distribution, to enable the voltage to be accurately distributed to different circuit nodes, thereby improving the accuracy of voltage distribution. The connection mode of the second resistor R2 and the third resistor R3 ensures the stability and consistency of the voltage at different nodes, effectively solving the problem of voltage distribution accuracy. Through this technical means, the peak current control circuit can achieve more accurate voltage control, thereby improving the overall performance and stability of the circuit.

[0042] In an embodiment, the control signal generation module includes a flip-flop 3 (for example, an RS flip-flop 3, i.e., a Reset-Set flip-flop 3, a bistable multivibrator 4), an oscillator 4, and a slope generator 5.

[0043] Specifically, the reset end of the flip-flop 3 is connected to the output end of the comparator 2, the set end of the flip-flop 3 is connected to the oscillator 4, and the output end of the flip-flop 3 is connected to the gate of the MOS tube Q5; the oscillator 4 is connected to the slope generator 5; and the slope generator 5 is connected to the non-inverting input end of the comparator 2.

[0044] The flip-flop 3, the oscillator 4, and the slope generator 5 in the control signal generation module of the embodiment jointly act to generate a signal for controlling the switching state of the MOS tube Q5. The flip-flop 3 is reset according to the output signal of the comparator 2 and is set by the set signal of the oscillator 4, and its output end directly controls the gate of the MOS tube Q5, thereby realizing control of the switching state of the MOS tube Q5. The oscillator 4 provides a timing signal for the flip-flop 3 and drives the slope generator 5 to generate a slope compensation signal, which is input to the non-inverting input end of the comparator 2 for comparison with the sampling signal collected by the detection module. Through the synergistic action of the above-mentioned devices, accurate control of the switching state of the MOS tube Q5 is realized, solving the problem of how to generate a control signal to accurately control the switching state of the MOS tube Q5.

[0045] Preferably, an adder is further arranged between the slope generator 5 and the comparator 2, for performing addition operation on the slope compensation signal generated by the slope generator 5 and the sampling signal collected by the detection module.

[0046] Specifically, the slope compensation signal generated by the slope generator 5 and the sampling signal collected by the detection module are respectively input to the adder, and when both input signals are high level, the adder outputs a high level signal, otherwise outputs a low level signal, so that the signal output from the adder to the comparator 2.

[0047] In the embodiment, when the reset end R of the flip-flop 3 is 1 and the set end S is 0, the output end Q of the flip-flop 3 is 0, and the MOS tube Q5 is off; when the reset end R of the flip-flop 3 is 0 and the set end S is 1, the output end Q of the flip-flop 3 is 1, and the MOS tube Q5 is on. The embodiment can realize the on and off of the MOS tube Q5 by controlling the states of the reset end and the set end of the flip-flop 3. The state transition of the flip-flop 3 directly determines the switching state of the MOS tube Q5, thereby realizing the accurate control of the current in the circuit.

[0048] In the embodiment, at the beginning of each switching cycle, the oscillator 4 sends a narrow pulse signal to the flip-flop 3 and the slope generator 5. By sending a narrow pulse signal to the flip-flop 3 and the slope generator 5, the oscillator 4 can ensure the correct operation of the flip-flop 3 and the slope generator 5, thereby realizing the accurate control of the peak current.

[0049] In a specific embodiment, the detection module is configured to collect the current and voltage signals of the to-be-controlled circuit and convert the current and voltage signals into sampling signals and send the sampling signals to the comparator 2; the error amplifier 1 is configured to receive a reference voltage and a feedback voltage from the voltage dividing module and perform difference amplification on the reference voltage and the feedback voltage to generate a first control signal; the control signal generation module is configured to generate a slope compensation signal and send the slope compensation signal to the comparator 2; the comparator 2 is configured to compare the sum of the sampling signal and the slope compensation signal with the control signal (i.e., the signal generated by the adder is sent to the comparator 2, and then the comparator 2 compares the two signals); the control signal generation module is further configured to output a second control signal to the power switch module according to the comparison result of the comparator 2; and the power switch module is configured to adjust the peak current in the to-be-controlled circuit according to the second control signal.

[0050] In the embodiment, the sampling signal collected by the detection module is directly compared with the first control signal of the error amplifier 1 at the input end of the pulse (PWM) comparator 2 (i.e., the comparator 2 of the embodiment), so as to control the duty cycle of the output pulse, so as to achieve the adjustment of the peak current of the output inductor L1 following the change of the error voltage. Here, the PWM pulse width is not directly controlled by the voltage error signal, but indirectly controlled by the peak inductor L1 current.

[0051] Figure 1The principle diagram of the PWM modulation switching power supply controlled by the PCM is shown in the figure. The error amplifier 1 amplifies the difference between the reference voltage and the feedback voltage to obtain the first control signal. Since the change of the feedback voltage is very small in a switching cycle, the first control signal can be considered as constant in the same switching cycle (i.e. the change of the feedback voltage in a switching cycle has little effect on the control signal). The first control signal is transmitted to the inverting input terminal of the comparator 2; the MOS sampling signal (i.e. the sampling signal collected by the detection module in the embodiment) and the ramp compensation signal are added to obtain the composite signal which is transmitted to the non-inverting input terminal of the PWM comparator 2.

[0052] The oscillator 4 controls the overall switching frequency. At the beginning of each switching cycle, the oscillator 4 synchronously sends the narrow pulse signal to the flip-flop 3 and the ramp generator 5. At this time, S=1 and R=0, the flip-flop 3 outputs Q=1, and the MOS transistor Q5 starts to conduct. After the narrow pulse disappears, the flip-flop 3 maintains the current state when S=0 and R=0, and the MOS transistor Q5 maintains the conducting state. The ramp compensation signal starts to linearly increase from 0V, the inductor L1 current starts to linearly increase, and the voltage also increases with the inductor L1 current. When the sum of the MOS sampling signal and the ramp compensation signal is greater than the control signal, the comparator 2 flips, R=1 and S=0, the flip-flop 3 outputs Q=0, and the MOS transistor Q5 is turned off until the oscillator 4 sends a new pulse signal to start the next switching cycle.

[0053] Control law: when the inductor L1 current rises to meet the condition that the sum of the MOS sampling signal and the ramp compensation signal is greater than the first control signal, the MOS transistor Q5 is turned off, and then the connection between the inductor L1 and the power supply (i.e. the power supply in the band control circuit) is disconnected. The inductor L1 current then linearly decreases until the inductor L1 current increases after the MOS transistor Q5 is turned on again in the next cycle. The current instantaneous value at the moment when the MOS transistor Q5 is turned off is the peak value of the inductor L1 current. It can be concluded that in each cycle, the control signal output by the voltage control outer ring is used to adjust the conduction of the MOS transistor Q5, thereby controlling the inductor L1 current, and the inductor L1 current instantaneous value in the current cycle.

[0054] Therefore, the embodiment can accurately control the peak current in the circuit through accurate current detection and comparison, can quickly respond to current change, timely adjust the state of the MOS tube Q5 switch, and ensure the stability of the circuit, adopts reasonable circuit structure and control algorithm, and improves the stability and reliability of the circuit.

[0055] In summary, the peak current control circuit has the following advantages:

[0056] The detection module, the error amplifier, the comparator, the voltage dividing module, the control signal generation module and the power switch module are arranged, one end of the detection module is used for collecting current and voltage signals of the to-be-controlled circuit, and the other end is grounded, the detection module is connected with the voltage dividing module and the power switch module, the non-inverting input end of the error amplifier is connected with a reference voltage, the inverting input end of the error amplifier is connected with the voltage dividing module, the output end of the error amplifier is connected with the inverting input end of the comparator, the non-inverting input end of the comparator is connected with the detection module and the control signal generation module, the output end of the comparator is connected with the control signal generation module, and the control signal generation module is connected with the power switch module.

[0057] Obviously, those skilled in the art can make various modifications and variations to the utility model without departing from the spirit and scope of the utility model. Thus, if these modifications and variations of the utility model belong to the scope of the utility model claims and the equivalent technology, the utility model also intends to include these modifications and variations.

Claims

1. A peak current control circuit, characterized by, The detection module, the error amplifier, the comparator, the voltage dividing module, the control signal generation module and the power switch module are included. One end of the detection module is used for collecting current and voltage signals of a to-be-controlled circuit, and the other end is grounded. The non-inverting input terminal of the error amplifier is connected to a reference voltage, the inverting input terminal of the error amplifier is connected to the voltage dividing module, and the output terminal of the error amplifier is connected to the inverting input terminal of the comparator. The non-inverting input terminal of the comparator is connected to the detection module and the control signal generation module, and the output terminal of the comparator is connected to the control signal generation module. The control signal generation module is connected to the power switch module.

2. The peak current control circuit of claim 1, wherein, The detection module includes an inductor and a first resistor. One end of the inductor is connected to a to-be-controlled circuit, and the other end is connected to the power switch module.

3. The peak current control circuit of claim 2, wherein, The power switch module includes a MOS tube, a diode and a capacitor. The source of the MOS tube is connected to the other end of the inductor and one end of the diode, the drain is connected to the first resistor, and the gate is connected to the control signal generation module.

4. The peak current control circuit of claim 3, wherein, The other end of the diode is connected to the capacitor and one end of the voltage dividing module. The voltage dividing module includes a second resistor and a third resistor.

5. The peak current control circuit of claim 4, wherein, One end of the second resistor is connected to the diode and one end of the capacitor, and the other end of the second resistor is connected to the third resistor. The control signal generation module includes a flip-flop, an oscillator and a slope generator. The reset end of the flip-flop is connected to the output terminal of the comparator, the set end is connected to the oscillator, and the output terminal is connected to the gate of the MOS tube.

6. The peak current control circuit of claim 5, wherein, The oscillator is connected to the slope generator, and the slope generator is connected to the non-inverting input terminal of the comparator.

7. The peak current control circuit of claim 5, wherein, An adder is further arranged between the slope generator and the comparator, and is used for performing addition operation on the slope compensation signal generated by the slope generator and the sampling signal collected by the detection module.

8. The peak current control circuit of claim 5, wherein, When the reset end R of the flip-flop is 1 and the set end S is 0, the output end Q of the flip-flop is 0, and the MOS tube is turned off.

9. The peak current control circuit of claim 5, wherein, When the reset end R of the flip-flop is 0 and the set end S is 1, the output end Q of the flip-flop is 1, and the MOS tube is turned on.

10. The peak current control circuit of claim 1, wherein, The oscillator is used for sending a narrow pulse signal to the flip-flop and the slope generator. The detection module is used for collecting current and voltage signals of a to-be-controlled circuit, and converting the current and voltage signals into sampling signals and sending the sampling signals to the non-inverting input terminal of the comparator. The error amplifier is used for receiving a reference voltage and a feedback voltage from the voltage dividing module, and performing difference amplification on the reference voltage and the feedback voltage to generate a first control signal. The control signal generation module is used for generating a slope compensation signal and sending the slope compensation signal to the non-inverting input terminal of the comparator. The comparator is configured to compare a sum of the sampling signal and a ramp compensation signal with the control signal; The control signal generation module is further configured to output a second control signal to the power switch module according to a comparison result of the comparator; The power switch module is configured to adjust the peak current in the to-be-controlled circuit according to the second control signal.

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