QR step-down circuit applied to power supply module

Abstract

The invention provides a QR step-down circuit applied to a power module, and relates to the technical field of power electronics, the QR step-down circuit comprises a control circuit, a driving circuit and a power circuit which cooperate with one another, and the control circuit is used for converting an input voltage into a required output voltage and maintaining the stability of the output voltage; meanwhile, the circuit state is monitored through a voltage feedback mechanism and a current feedback mechanism, and circuit abnormity protection is achieved; the driving circuit is connected with the control circuit and is used for receiving and amplifying a control signal from the control circuit; and the power circuit is connected with the driving circuit, works based on a quasi-resonance principle, and is used for receiving the control signal amplified by the driving circuit, converting an input voltage into an output voltage through periodic on-off of a switching element and performing power conversion. The circuit efficiency is improved, and the problems of low efficiency, large electromagnetic interference and the like in an existing step-down circuit are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a QR step-down circuit applied to a power module. Background Art

[0002] In power electronic systems, the buck circuit is the core component of the power module, responsible for converting high-voltage DC into low-voltage DC to meet the working requirements of subsequent circuits. However, traditional buck circuits face many challenges in practical applications.

[0003] On the one hand, the traditional linear buck circuit achieves voltage reduction by adjusting the conduction degree of the transistor to consume excess voltage. This method has low efficiency, especially when the input and output voltage difference is large, a large amount of electrical energy is lost in the form of heat energy, resulting in overall low efficiency.

[0004] On the other hand, although the switching buck circuit improves efficiency by periodically switching on and off the switch tube, the efficiency will still drop significantly under light load due to the increase in switching losses. In addition, the rapid changes in voltage and current during the switching process will generate strong electromagnetic interference, which will have a negative impact on surrounding electronic equipment, and additional EMI filtering components are required to suppress the interference.

[0005] Therefore, it is necessary to provide a QR buck circuit applied to a power module to solve the above technical problems. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a QR buck circuit applied to a power module, which solves the problems of low efficiency and large electromagnetic interference in the existing buck circuit by adopting quasi-resonance control technology, efficient current detection and protection mechanism, and optimizing circuit layout and component parameters. The circuit has the advantages of simple structure, high efficiency, low electromagnetic interference, etc., and can be widely used in various power modules, providing a strong guarantee for the efficient and stable operation of power electronic systems.

[0007] The present invention provides a QR buck circuit applied to a power module, comprising the following sub-circuits cooperating with each other: The control circuit is used to convert the input voltage into the required output voltage and maintain the stability of the output voltage; at the same time, the circuit state is monitored through the voltage feedback mechanism and the current feedback mechanism to achieve circuit abnormality protection; A driving circuit, connected to the control circuit, for receiving and amplifying a control signal from the control circuit; The power circuit is connected to the driving circuit and works based on the quasi-resonance principle. It is used to receive the amplified control signal from the driving circuit and convert the input voltage into the output voltage and perform power conversion by periodically turning on and off the switching element.

[0008] Preferably, the control circuit includes a control chip U21, and resistors R78, R50, R63, R5, R64, R14, R39, R60, R76, capacitors C13, C14, C35, C11, diodes D7, D13, and D16 connected thereto, wherein: The control chip U21 is used to stabilize the output voltage, realize voltage conversion, and shut down the circuit when the circuit output is abnormal through voltage feedback mechanism and current feedback mechanism; Resistor R78 and capacitor C13 together form a filtering network for the voltage feedback signal; Resistor R63 is used to set the switching frequency of the circuit; The resistor R39 and the capacitor C35 together form a filter network for the current detection signal; Resistors R64, R5, R14, and diode D13 together realize zero-crossing detection of the power circuit; The input voltage passes through diode D7 and resistor R60 and is connected to the control chip U21 to provide a starting voltage for it; The auxiliary power supply is connected to the VDD pin of the control chip U21 through the diode D16 and the resistor R76 to provide a stable power supply.

[0009] Preferably, the driving circuit includes a driving chip U23, and resistors R53, R40, R164, capacitors C189, C190, C191, C196, diode D50, voltage regulator D56, and voltage regulator D36 connected thereto, wherein: The driving chip U23 is used to amplify the control signal sent by the control chip U21; Resistor R53 is used as a driving resistor to reduce the ringing phenomenon generated when the power MOS tube is turned on; Diode D50 is used to achieve fast shutdown of the drive circuit; Capacitor C189 is used to provide filtering for the driver chip.

[0010] Preferably, the power circuit includes a current transformer TR1, a resistor R124, a resistor R126, a resistor R125, a resistor R157, a resistor R122, a resistor R123, a capacitor C171, a capacitor C172, a capacitor C173, a capacitor C159, a capacitor C160, a MOS tube Q14, diodes D34, D32, D28, and an inductor L2, wherein: Resistor R124, resistor R126, resistor R125 and diode D28 together with current transformer TR1 form a detection circuit for converting the input large current into a small current and sending it to the control chip U; The MOS tube Q14, the diode D34 and the inductor L2 together form a step-down circuit, wherein the MOS tube Q14 is used to chop the input DC voltage into a pulse voltage; Inductor L2 and capacitors C171, C172, C173, C159 and C160 are used to smooth the pulse voltage into a stable output voltage.

[0011] Compared with the related art, the QR buck circuit applied to the power module provided by the present invention has the following beneficial effects: The present invention adopts quasi-resonance control technology, and accurately controls the switch tube to turn on at the resonance valley by detecting the voltage waveform on the energy storage inductor. This control technology not only significantly reduces the turn-on loss and improves the circuit efficiency, but also reduces the overlapping area of ​​voltage and current, further reducing the switching loss.

[0012] The present invention sets a current detection element and a protection mechanism in the circuit. By detecting the magnitude and change of the input current, the on and off states of the switch tube are adjusted in real time to ensure that the circuit can respond quickly and shut down the circuit in abnormal situations such as overload and short circuit, thus protecting the circuit elements from damage.

[0013] In order to reduce electromagnetic interference, the present invention optimizes the circuit layout and component parameters. By rationally arranging circuit components, selecting appropriate component parameters, and adding necessary filtering components, the generation and propagation of electromagnetic interference are effectively suppressed, and the electromagnetic compatibility of the circuit is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the overall circuit diagram of the present invention; Figure 2 A circuit diagram of a control circuit of the present invention; Figure 3 is a circuit diagram of a driving circuit of the present invention; Figure 4 is a circuit diagram of a power circuit of the present invention. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings. In addition, the embodiments of the present invention and the features in the embodiments may be combined with each other without conflict.

[0016] It should also be noted that, for ease of description, only the parts related to the present invention, but not all of the contents, are shown in the accompanying drawings. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations (or steps) as sequential processes, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but it can also have additional steps not included in the accompanying drawings. The process can correspond to methods, functions, procedures, subroutines, subprograms, etc.

[0017] It should be noted that in the field of power modules, traditional buck circuits mainly include linear buck circuits and ordinary switch-type buck circuits. The linear buck circuit consumes excess voltage by adjusting the conduction degree of the transistor to achieve the purpose of voltage reduction, but its efficiency is low, especially when the input and output voltage difference is large, a large amount of energy is dissipated in the form of heat energy, which is not conducive to the effective use of energy. Although the efficiency of ordinary switch-type buck circuits is relatively high, the efficiency will drop significantly under light load, and the rapid voltage and current changes during the switching process will generate large electromagnetic interference, which requires additional EMI filtering components to suppress. In addition, large switching losses are also a significant defect of traditional buck circuits, which limits the increase in switching frequency and the optimization of overall efficiency.

[0018] Therefore, in response to the above-mentioned defects of the existing step-down circuit, the present application proposes a QR step-down circuit applied to a power module. The circuit adopts QR technology to detect the voltage waveform on the energy storage inductor, so that the switch tube is turned on or off when the voltage is close to zero, thereby realizing soft switching, thereby reducing switching losses, improving circuit efficiency, and reducing the generation of electromagnetic interference.

[0019] refer to Figures 1 to 4 As shown, the QR buck circuit of the present application mainly includes three parts: a control circuit, a drive circuit and a power circuit. Among them, the control circuit is responsible for realizing the overall control of the circuit, and has functions such as voltage conversion, output voltage stability and circuit abnormality protection. The drive circuit is used to enhance the drive signal output by the control chip and improve the driving ability of the chip. The power circuit realizes power conversion and stably reduces the input high-voltage DC to the low-voltage DC required by the next stage. The three work closely together to form an efficient and stable QR buck circuit.

[0020] More specifically, the control circuit is the core part of the QR buck circuit, which is mainly responsible for the overall control and protection of the circuit. The circuit mainly includes chip U21 and a series of components such as resistors, capacitors and diodes.

[0021] As the controller of the entire circuit, the control chip U21 is responsible for stabilizing the output voltage and realizing voltage conversion. Through the internal feedback control mechanism, the output voltage changes are monitored in real time and adjusted to ensure that the output voltage remains stable within a certain accuracy range. At the same time, the control chip U21 also has a circuit abnormality protection function. When a circuit abnormality is detected, the circuit can be shut down in time to protect the circuit components from damage.

[0022] Among them, resistor R78 and capacitor C13 together constitute a filter network for the voltage feedback signal to ensure the accuracy of the feedback signal. Resistor R63 is used to set the switching frequency of the circuit. Resistor R39 and capacitor C35 constitute a filter network for the current detection signal, and the detected current signal is sent to the control chip U21 for processing. In addition, resistors R64, R5, R14 and diode D13 together realize the zero-crossing detection function of the power circuit and provide a zero-crossing detection signal for the control chip.

[0023] Diodes D7 and D16 are used for input voltage rectification and auxiliary power supply isolation respectively. D7 rectifies the input AC voltage into DC voltage to provide a stable input voltage for the circuit. D16 is used for auxiliary power supply isolation to ensure the stability and reliability of the auxiliary power supply.

[0024] The drive circuit is a key part of the QR buck circuit, which is mainly responsible for enhancing the drive signal output by the control chip and improving the chip's driving ability. The circuit mainly includes the control chip U23 and a series of components such as resistors, capacitors, diodes and voltage regulators.

[0025] The control chip U23 is used as a driving chip to amplify the driving signal sent by the control chip U21 to enhance the driving ability of the signal. The amplified driving signal can more reliably control the switch tube in the power circuit to conduct and shut down operations.

[0026] Resistor R53 is used as a driving resistor to reduce the ringing phenomenon when the power MOS tube is turned on and improve the reliability of the circuit. Resistors R40 and R164 are used to adjust the amplitude and phase of the driving signal to ensure that the driving signal matches the switch tube in the power circuit well.

[0027] Capacitor C189 provides a stable power supply voltage for the driver chip U23 to ensure the stability and reliability of the drive signal. In addition, capacitors C190, C191 and C196 are also used to filter out high-frequency noise and interference in the drive signal to improve the purity of the drive signal.

[0028] Diode D50 realizes the fast shutdown function of the drive circuit. When the switch tube needs to be turned off, D50 can quickly pull down the drive signal to ensure that the switch tube can be turned off in time. The voltage regulator diodes D56 and D36 are used to protect the drive circuit from damage due to abnormal conditions such as overvoltage and overcurrent.

[0029] The power circuit is the executive part of the QR step-down circuit, which is mainly responsible for realizing power conversion and stably reducing the input high-voltage DC to the low-voltage DC required by the subsequent stage. The circuit mainly includes components such as current transformers, resistors, capacitors, MOS tubes, diodes and inductors.

[0030] The current transformer TR2 is responsible for detecting the input current and converting the input large current into a small current signal to be sent to the control chip U21 for processing. By monitoring the changes in the input current, the control chip can control and protect the current of the power circuit.

[0031] Resistors R124, R126, R125, diode D28 and current transformer TR2 together realize the input current detection function. Resistors R157, R122 and R123 are used to adjust the current and voltage distribution in the power circuit to ensure the stability and reliability of the circuit.

[0032] Capacitors C171, C172, C173, C159 and C160 are used to filter out high-frequency noise and interference in the power circuit and improve the stability and purity of the output voltage. At the same time, these capacitors also play the role of energy storage and smoothing the output voltage.

[0033] MOS tube Q14 is a switch tube in the power circuit. Q14 realizes continuous on and off operation through the control of the driving signal. When it is on, Q14 chops the input DC voltage into a series of pulse voltages; when it is off, it smoothes the pulse voltage into a stable output voltage through the action of the energy storage inductor L2 and the filter capacitor.

[0034] When the switch tube Q14 is turned off, the energy storage inductor L2 will generate a reverse electromotive force to maintain the continuity of the current. At this time, the diode D34 provides a path for the inductor current to prevent the reverse electromotive force generated by the inductor from damaging other circuit components. At the same time, D34 also plays the role of rectification and voltage reduction, releasing the energy in the energy storage inductor L2 to the output end.

[0035] Inductor L2 acts as an energy storage element, storing energy when switch tube Q14 is turned on, and releasing energy when Q14 is turned off to maintain the stability of the output voltage. Through the energy storage and release of L2, the input DC voltage can be smoothly reduced to the required low voltage DC.

[0036] In summary, the QR buck circuit of the present application has the following advantages over the traditional buck circuit: In terms of working principle, traditional buck circuits, such as linear buck circuits, reduce voltage by adjusting the conduction degree of transistors and consuming excess voltage in the form of heat energy; switch-type buck circuits use the periodic on and off of the switch tube to convert the input voltage into a pulse signal, which is then reduced through inductor and capacitor energy storage and filtering. The QR buck circuit is based on the quasi-resonance principle. When the switch tube is turned on, it is turned on at the bottom of the resonance valley to achieve a near-zero voltage turn-on, reducing turn-on losses.

[0037] In terms of efficiency, traditional buck circuits such as linear buck circuits are inefficient, especially when the input-output voltage difference is large; ordinary switch-type buck circuits will have reduced efficiency at light loads. However, the QR buck circuit can maintain high efficiency at both light and heavy loads by reducing switching losses, and the power frequency can be adjusted according to the load to further improve efficiency.

[0038] In terms of switching losses, the voltage and current of the switch tube of the traditional buck circuit change quickly and overlap a large area during the switching process, resulting in large switching losses, which limits the switching frequency and efficiency improvement. The QR buck circuit uses quasi-resonant operation to turn on or off the switch tube when the voltage or current is close to zero, greatly reducing the switching losses.

[0039] In terms of electromagnetic interference, the rapid voltage and current changes during the switching process of the traditional buck circuit will produce strong electromagnetic interference, requiring more EMI filtering components. However, the switching action of the QR buck circuit is closer to the ideal state, the electromagnetic interference generated is relatively small, and it is easier to meet the electromagnetic compatibility requirements.

[0040] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0041] A person skilled in the art may understand that all or part of the steps in the various methods of the above embodiments may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, the storage medium including a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically-erasable programmable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0042] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

Claims

1. A QR step-down circuit applied to a power module, characterized in that: It includes the following sub-circuits that work together: The control circuit is used to convert the input voltage into the required output voltage and maintain the stability of the output voltage; at the same time, the circuit state is monitored through the voltage feedback mechanism and the current feedback mechanism to achieve circuit abnormality protection; A driving circuit, connected to the control circuit, for receiving and amplifying a control signal from the control circuit; The power circuit is connected to the driving circuit and works based on the quasi-resonance principle. It is used to receive the amplified control signal from the driving circuit and convert the input voltage into the output voltage and perform power conversion by periodically turning on and off the switching element.

2. A QR buck circuit for a power module according to claim 1, characterized in that: The control circuit includes a control chip U21, and resistors R78, R50, R63, R5, R64, R14, R39, R60, R76, capacitors C13, C14, C35, C11, diodes D7, D13, and D16 connected thereto, wherein: The control chip U21 is used to stabilize the output voltage, realize voltage conversion, and shut down the circuit when the circuit output is abnormal through voltage feedback mechanism and current feedback mechanism; Resistor R78 and capacitor C13 together form a filtering network for the voltage feedback signal; Resistor R63 is used to set the switching frequency of the circuit; The resistor R39 and the capacitor C35 together form a filter network for the current detection signal; Resistors R64, R5, R14, and diode D13 together realize zero-crossing detection of the power circuit; The input voltage passes through diode D7 and resistor R60 and is connected to the control chip U21 to provide a starting voltage for it; The auxiliary power supply is connected to the VDD pin of the control chip U21 through the diode D16 and the resistor R76 to provide a stable power supply.

3. A QR step-down circuit applied to a power module according to claim 2, characterized in that: The driving circuit includes a driving chip U23, and connected thereto resistors R53, R40, R164, capacitors C189, C190, C191, C196, diode D50, voltage regulator D56, and voltage regulator D36, wherein: The driving chip U23 is used to amplify the control signal sent by the control chip U21; Resistor R53 is used as a driving resistor to reduce the ringing phenomenon generated when the power MOS tube is turned on; Diode D50 is used to achieve fast shutdown of the drive circuit; Capacitor C189 is used to provide filtering for the driver chip.

4. A QR step-down circuit for a power module according to claim 3, characterized in that: The power circuit includes a current transformer TR1, a resistor R124, a resistor R126, a resistor R125, a resistor R157, a resistor R122, a resistor R123, a capacitor C171, a capacitor C172, a capacitor C173, a capacitor C159, a capacitor C160, a MOS tube Q14, diodes D34, D32, D28, and an inductor L2, wherein: Resistor R124, resistor R126, resistor R125 and diode D28 together with current transformer TR1 form a detection circuit for converting the input large current into a small current and sending it to the control chip U; The MOS tube Q14, the diode D34 and the inductor L2 together form a step-down circuit, wherein the MOS tube Q14 is used to chop the input DC voltage into a pulse voltage; Inductor L2 and capacitors C171, C172, C173, C159 and C160 are used to smooth the pulse voltage into a stable output voltage.

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